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FLASH radiotherapy, which refers to the delivery of radiation at ultra-high doserates (UHDRs), has been demonstrated with various forms of radiation and is the subject of intense research and development recently, including the use of very high-energy electrons (VHEEs) to treat deep-seated tumors. Delivering FLASH radiotherapy in a clinical setting is expected to place high demands on real-time quality assurance and dosimetry systems. Furthermore, very high-energy electron research currently requires the transformation of existing nonmedical accelerators into radiotherapy research environments. Accurate dosimetry is crucial for any such transformation. In this article, we assess the response of the MOSkin, developed by the Center for Medical Radiation Physics, which is designed for on-patient, real-time skin dose measurements during radiotherapy, and whether it exhibits dose-rate independence when exposed to 100 MeV electron beams at the Pulsed Energetic Electrons for Research (PEER) end-station. PEER utilizes the electron beam from a 100 MeV linear accelerator when it is not used as the injector for the ANSTO Australian Synchrotron. With the estimated pulse dose-rates ranging from (7.84 ± 0.21) χ 10[sup 5] Gy/s to (1.28 ± 0.03) χ 10[sup 7] Gy/s and an estimated peak bunch dose-rate of (2.55 ± 0.06) χ 10[sup 8] Gy/s, MOSkin measurements were verified against a scintillating screen to confirm that the MOSkin responds proportionally to the charge delivered and, therefore, exhibits dose-rate independence in this irradiation environment. [ABSTRACT FROM AUTHOR]

While ionizing radiation plays a pivotal role in precise diagnosis and treatment, it concurrently engenders risks, including an elevated incidence of cancer. The research speaks to the discernible decline in quality assurance programmes and dose measurement endeavors within Nigerian imaging facilities, with a substantial portion lacking established protocols for routine machine calibration and dose measurement. This study encompasses a large-scale survey involving 307 adult patients undergoing routine X-ray procedures in two hospitals in Nigeria. Thermo-luminescent dosimeters (TLDs) were used for measuring Entrance Skin Dose (ESD). The mean ESD values ranged from 1.16 mGy to a maximum of 3.94 mGy. Notably, these values were predominantly below the dose reference levels (DRLs) established by reputable bodies such as NRPB, CEC, IAEA, and UK for most examinations. The main purpose of this study was to determine the diagnostic reference level (DRL) for routine digital radiography examinations in Nigeria. [ABSTRACT FROM AUTHOR]

Purpose: To evaluate the accuracy of different dosimeters and the treatment planning system (TPS) for assessing the skin dose due to the electron streaming effect (ESE) on a 1.5 T magnetic resonance (MR)‐linac. Method: Skin dose due to the ESE on an MR‐linac (Unity, Elekta) was investigated using a solid water phantom rotated 45° in the x‐y plane (IEC61217) and centered at the isocenter. The phantom was irradiated with 1 × 1, 3 × 3, 5 × 5, 10 × 10, and 22 × 22 cm2 fields, gantry at 90°. Out‐of‐field doses (OFDs) deposited by electron streams generated at the entry and exit surface of the angled phantom were measured on the surface of solid water slabs placed ±20.0 cm from the isocenter along the x‐direction. A high‐resolution MOSkin™ detector served as a benchmark due to its shallower depth of measurement that matches the International Commission on Radiological Protection (ICRP) recommended depth for skin dose assessment (0.07 mm). MOSkin™ doses were compared to EBT3 film, OSLDs, a diamond detector, and the TPS where the experimental setup was modeled using two separate calculation parameters settings: a 0.1 cm dose grid with 0.2% statistical uncertainty (0.1 cm, 0.2%) and a 0.2 cm dose grid with 3.0% statistical uncertainty (0.2 cm, 3.0%). Results: OSLD, film, the 0.1 cm, 0.2%, and 0.2 cm, 3.0% TPS ESE doses, underestimated skin doses measured by the MOSkin™ by as much as –75.3%, –7.0%, –24.7%, and –41.9%, respectively. Film results were most similar to MOSkin™ skin dose measurements. Conclusions: These results show that electron streams can deposit significant doses outside the primary field and that dosimeter choice and TPS calculation settings greatly influence the reported readings. Due to the steep dose gradient of the ESE, EBT3 film remains the choice for accurate skin dose assessment in this challenging environment. [ABSTRACT FROM AUTHOR]

Background Purpose Methods Results Conclusions The Alberta rotating biplanar linac‐MR has a 0.5 T magnetic field parallel to the beamline. When developing a new linac‐MR system, interactions of charged particles with the magnetic field necessitate careful consideration of skin dose and tissue interface effects.To investigate the effect of the magnetic field on skin dose using measurements and Monte Carlo (MC) simulations.We develop an MC model of our linac‐MR, which we validate by comparison with ion chamber measurements in a water tank. Additionally, MC simulation results are compared with radiochromic film surface dose measurements on solid water. Variations in surface dose as a function of field size are measured using a parallel plate ion chamber in solid water. Using an anthropomorphic computational phantom with a 2 mm‐thick skin layer, we investigate dose distributions resulting from three beam arrangements. Magnetic field on and off scenarios are considered for all measurements and simulations.For a 20 × 20 cm2 field size, D0.2cc${D_{0.2cc}}$ (the minimum dose to the hottest contiguous 0.2 cc volume) for the top 2 mm of a simple water phantom is 72% when the magnetic field is on, compared to 34% with magnetic field off (values are normalized to the central axis dose maximum). Parallel plate ion chamber measurements demonstrate that the relative increase in surface dose due to the magnetic field decreases with increasing field size. For the anthropomorphic phantom, D∼0.2cc${D_{ \sim 0.2cc}}$ (minimum skin dose in the hottest 1 × 1 × 1 cm3 cube) shows relative increases of 20%–28% when the magnetic field is on compared to when it is off. With magnetic field off, skin D∼0.2cc${D_{ \sim 0.2cc}}$ is 71%, 56%, and 21% for medial‐lateral tangents, anterior‐posterior beams, and a five‐field arrangement, respectively. For magnetic field on, the corresponding skin D∼0.2cc${D_{ \sim 0.2cc}}$ values are 91%, 67%, and 25%.Using a validated MC model of our linac‐MR, surface doses are calculated in various scenarios. MC‐calculated skin dose varies depending on field sizes, obliquity, and the number of beams. In general, the parallel linac‐MR arrangement results in skin dose enhancement due to charged particles spiraling along magnetic field lines, which impedes lateral motion away from the central axis. Nonetheless, considering the results presented herein, treatment plans can be designed to minimize skin dose by, for example, avoiding oblique beams and using a larger number of fields. [ABSTRACT FROM AUTHOR]

With the increasing use of flattening filter free (FFF) beams, it is important to evaluate the impact on the skin dose and target coverage of breast cancer treatments. This study aimed to compare skin doses of treatments using FFF and flattening filter (FF) beams for breast cancer. The study established treatment plans for left breast of an anthropomorphic phantom using Halcyon's 6-MV FFF beam and TrueBeam's 6-MV FF beam. Volumetric modulated arc therapy (VMAT) with varying numbers of arcs and intensity modulated radiation therapy (IMRT) were employed, and skin doses were measured at five points using Gafchromic EBT3 film. Each measurement was repeated three times, and averaged to reduce uncertainty. All plans were compared in terms of plan quality to ensure homogeneous target coverage. The study found that when using VMAT with two, four, and six arcs, in-field doses were 19%, 15%, and 6% higher, respectively, when using Halcyon compared to TrueBeam. Additionally, when using two arcs for VMAT, in-field doses were 10% and 15% higher compared to four and six arcs when using Halcyon. Finally, in-field dose from Halcyon using IMRT was about 1% higher than when using TrueBeam. Our research confirmed that when treating breast cancer with FFF beams, skin dose is higher than with traditional FF beams. Moreover, number of arcs used in VMAT treatment with FFF beams affects skin dose to the patient. To maintain a skin dose similar to that of FF beams when using Halcyon, it may be worth considering increasing the number of arcs. [ABSTRACT FROM AUTHOR]

Objective: The purpose of this study was to assess patient dose and investigate the parameters affecting patient's dose during fluoroscopy guided procedures at a hospital for possible dose reduction. Methods: Standard quality control tests were performed prior to the data collection. Twelve (12) thermoluminescent dosimeters TLDs were arranged on a Perspex phantom for skin dose measurement. Skin dose (SD) and Kerma Area Product (KAP) were recorded for varying radiation field size at fix phantom thickness and vice versa. Doses were assessed on one-hundred and one (101) patients undergoing barium swallow (BaS), retrograde (Rtr) and hysterosalpingoraphy (HSG). Results and discussion: The mean fluoroscopy time (FT) for Rtr, BaS and HSG procedures were 1 ± 0.67 min, 2.12 ± 1.30 min and 0.66 ± 0.5 min respectively. The mean KAP values were 8.21 ± 6.05 Gy.cm2, 87.33 ± 31.2 Gy.cm2 and 6.01 ± 3.25 Gy.cm2 for Rtr, BaS and HSG. The mean skin dose (SD) values for the cited procedures were 11.64 ± 1.25 mGy, 121.80 ± 40.87 mGy and 7.55 ± 2.58 mGy. It was found that patient skin dose increase rapidly with the phantom thickness (factor ≈ 2) as compared with the field size (factor ≈ 1). The SD variation with field size for the same thickness was negligible but the KAP values increase considerably with field size. The mean KAP value obtained was found to be higher with average factors of 2 and 2.5 for Rtr and HSG respectively. The regression analysis shows that there is a poor correlation (R2 =0.33) between ESD and KAP but a significant statistical significance (P-value = 0.003). It also shows that the SD in this study can be predictable with known fluoroscopy time for HSG and retrograde procedures at 77% and 52% accuracy respectively. Conclusion: The main contributor of patient's dose (i.e. SD) was patient thickness which cannot be regulated by the staff. Other factors that can be regulated by the staff to reduce patient's dose were the fluoroscopy time for HSG and Rtr procedures and the use of smaller field size as possible without compromising the clinical outcome. [ABSTRACT FROM AUTHOR]

FLASH radiotherapy, which refers to the delivery of radiation at ultra-high dose-rates (UHDRs), has been demonstrated with various forms of radiation and is the subject of intense research and development recently, including the use of very high-energy electrons (VHEEs) to treat deep-seated tumors. Delivering FLASH radiotherapy in a clinical setting is expected to place high demands on real-time quality assurance and dosimetry systems. Furthermore, very high-energy electron research currently requires the transformation of existing non-medical accelerators into radiotherapy research environments. Accurate dosimetry is crucial for any such transformation. In this article, we assess the response of the MOSkin, developed by the Center for Medical Radiation Physics, which is designed for on-patient, real-time skin dose measurements during radiotherapy, and whether it exhibits dose-rate independence when exposed to 100 MeV electron beams at the Pulsed Energetic Electrons for Research (PEER) end-station. PEER utilizes the electron beam from a 100 MeV linear accelerator when it is not used as the injector for the ANSTO Australian Synchrotron. With the estimated pulse dose-rates ranging from (7.84±0.21)×105 Gy/s to (1.28±0.03)×107 Gy/s and an estimated peak bunch dose-rate of (2.55±0.06)×108 Gy/s, MOSkin measurements were verified against a scintillating screen to confirm that the MOSkin responds proportionally to the charge delivered and, therefore, exhibits dose-rate independence in this irradiation environment.

Nuclear medicine healthcare workers are exposed to the risk of radioactive needlestick injury. To quantify the severity of this risk, the activity deposited into the skin and the injury depth have been experimentally measured for input into skin dosimetry program VARSKIN+. Agar test objects were pierced by hand with a needle containing Tc-99m Hydroxymethylene Diphosphonate (HMDP). The deposited activity was measured by contamination monitor and converted into deposited volume. Injury depth was measured with a ruler by piercing the test objects with visible dye.The median volume deposited into test objects without gloves was 100 ± 50 nl (standard error) (interquartile range (IQR): 50–320 nl). Through one glove, this was reduced to 50 ± 20 nl (IQR: 30 - 140 nl), however, the difference was not significant (p > 0.1). The volume deposited through two gloves was highly variable due to the increased force required to puncture. The median injury depth was 4.0 ± 0.4 mm (standard error).Decontamination efficacy was investigated by rinsing alone, with hand soap and by application of decontamination agent RadiacWash. All decontamination methods were found to significantly decrease the activity deposited (p < 0.001). Test objects rinsed for 60 s had a mean reduction of 42 % ± 6 % (95 % confidence interval). There was no significant difference observed between decontamination methods. This may be due to differences in absorption time between the sample groups.Skin dose estimates have been calculated in VARSKIN+ using the results of the experiment. For injuries without gloves, involving 1011 MBq/ml of Tc-99m HMDP, a skin dose of 11 ± 5 mSv (propagated standard error) was calculated. Immediate decontamination under running water is recommended to reduce the dose. Further research is encouraged to investigate the protection offered by gloves.

In radiotherapy, tissue equivalent boluses are frequently used in the treatment of superficially located tumors. The air gap between the patient's skin and the bolus may cause dosimetric uncertainties. This study aims to dosimetrically investigate the effect of the air gap between the surface and the bolus on dose distribution. Computed tomography (CT) images of the phantom were obtained and transferred to the treatment planning system (TPS). In the TPS, a bolus was placed on the phantom surface and then air gaps were created between the bolus and the surface. The effect of the air gaps between the surface and the 5 mm thick bolus on the dose distribution was analyzed with the point doses obtained from the TPS. For the 6 MV X-ray, it was observed that the air gap negatively affected the surface doses calculated by TPS. Accordingly, an inverse correlation was found between air gap and surface dose. It is recommended that bolus use, especially in curved anatomical regions, should be applied before CT scanning as much as possible. When using bolus material in radiotherapy, it is recommended to be careful not to leave an air gap between the surface and the bolus. [ABSTRACT FROM AUTHOR]

Objective(s): The aim of this study was to determine the entrance skin dose distribution for breast cancer patients who undergo radiotherapy in the presence of bolus containing gold and Fe3O4 nanoparticles to evaluate and compare the changes in dose distribution.Materials and Methods: Gold and Fe3O4 nanoparticles can increase the rate of photoelectric, Compton, and pair production absorption of x-ray photons. Nanoparticles were simulated in the bolus, over the skin of a breast phantom, by the exertion of MCNPX Monte Carlo code. The skin dose was also experimentally measured by using a bolus that contained homogeneously distributed Fe3O4 nanoparticles on the surface of a slab phantom and an advanced Markus chamber. Results: A significant skin dose enhancement was obtained for the case that 25 nm gold and Fe3O4 nanoparticles with 3% concentration were uniformly distributed in the bolus. However, increased concentration of nanoparticles in the bolus will increase the skin dose.Conclusion: It is concluded that using nanoparticles in the bolus leads to a significant skin dose enhancement for 6 MV x-ray photons. Furthermore, this study suggested that, less thick blouses may provide the same dose distribution.

Purpose: The dose expansion methods as the skin flash and virtual bolus were used to solve intrafraction movement for breast planning due to breathing motion. We investigated the skin dose in each planning method by using optically stimulated luminescence on an in-house moving phantom for breast cancer treatment in tomotherapy. The impact of respiratory motion on skin dose between static and dynamic phantom's conditions was evaluated. Methods: A phantom was developed with movement controlled by the respirator for generating the respiratory waveforms to simulate respiratory motion. Five optically stimulated luminescence dosimeters were placed on the phantom surface to investigate the skin dose for the TomoDirect and TomoHelical under static and dynamic conditions. Eight treatment plans were generated with and without skin flash or virtual bolus by varying the thickness. The difference in skin dose between the two phantom conditions for each plan was explored. Results: All plans demonstrated a skin dose of more than 87% of the prescription dose under static conditions. However, the skin dose was reduced to 84.1% (TomoDirect) and 78.9% (TomoHelical) for dynamic conditions. The treatment plans without skin flash or virtual bolus showed significant skin dose differences under static and dynamic conditions by 4.83% (TomoDirect) and 9.43% (TomoHelical), whereas the skin flash with two leaves (TomoDirect 2L) or virtual bolus of at least 1.0 cm thickness (VB1.0) application compensated the skin dose in case of intrafraction movements by presenting a skin dose difference of less than 2% between the static and dynamic conditions. Conclusion: The skin dose was reduced under dynamic conditions due to breathing motion. The skin flash method with TomoDirect 2L or virtual bolus application with 1.0 cm thickness was useful for maintaining skin dose following the prescription by compensating for intrafraction movement due to respiratory motion for breast cancer in tomotherapy. [ABSTRACT FROM AUTHOR]

Purpose: This research aimed to analyze electron stream effect (ESE) during magnetic resonance image guided radiotherapy (MRgRT) for breast cancer patients on a MR-Linac (0.35 Tesla, 6MV), with a focus on the prevention of redundant radiation exposure. Materials and methods: RANDO phantom was used with and without the breast attachment in order to represent the patients after breast conserving surgery (BCS) and those received modified radical mastectomy (MRM). The prescription dose is 40.05 Gy in fifteen fractions for whole breast irradiation (WBI) or 20 Gy single shot for partial breast irradiation (PBI). Thirteen different portals of intensity-modulated radiation therapy were created. And then we evaluated dose distribution in five areas (on the skin of the tip of the nose, the chin, the neck, the abdomen and the thyroid.) outside of the irradiated field with and without 0.35 Tesla. In addition, we added a piece of bolus with the thickness of 1cm on the skin in order to compare the ESE difference with and without a bolus. Lastly, we loaded two patients' images for PBI comparison. Results: We found that 0.35 Tesla caused redundant doses to the skin of the chin and the neck as high as 9.79% and 5.59% of the prescription dose in the BCS RANDO model, respectively. For RANDO phantom without the breast accessory (simulating MRM), the maximal dose increase were 8.71% and 4.67% of the prescription dose to the skin of the chin and the neck, respectively. Furthermore, the bolus we added efficiently decrease the unnecessary dose caused by ESE up to 59.8%. Conclusion: We report the first physical investigation on successful avoidance of superfluous doses on a 0.35T MR-Linac for breast cancer patients. Future studies of MRgRT on the individual body shape and its association with ESE influence is warranted. [ABSTRACT FROM AUTHOR]

Proton treatment may deliver a larger dose to a patient’s skin than traditional photon therapy, especially when a range shifter (RS) is inserted in the beam path. This study investigated the effects of an RS on skin dose while considering RS with different thicknesses, airgaps and materials. First, the physical model of the scanning nozzle with RS was established in the TOol for PArticle Simulation (TOPAS) code, and the effects of the RS on the skin dose were studied. Second, the variations in the skin dose and isocenter beam size were examined by reducing the air gap. Finally, the effects of different RS materials, such as polymethylmethacrylate (PMMA), Lexan, polyethylene and polystyrene, on the skin dose were analysed. The results demonstrated that the current RS design had a negligible effect on the skin dose, whereas the RS significantly impacted the isocenter beam size. The skin dose was increased considerably when the RS was placed close to the phantom. Moreover, the magnitude of the increase was related to the thickness of the inserted RS. Meanwhile, the results also revealed that the secondary proton primarily contributed to the increased skin dose.

To inform clinical practice for women receiving post-mastectomy radiotherapy (PMRT), this study demonstrates the dosimetric impact of removing daily bolus on skin and subcutaneous tissue. Two planning strategies were used: clinical field-based (n = 30) and volume-based planning (n = 10). The clinical field-based plans were created with bolus and recalculated without bolus for comparison. The volume-based plans were created with bolus to ensure a minimum target coverage of the chest wall PTV and recalculated without bolus. In each scenario, the dose to superficial structures, including skin (3 mm and 5 mm) and subcutaneous tissue (a 2 mm layer, 3 mm deep from surface) were reported. Additionally, the difference in the clinically evaluated dosimetry to skin and subcutaneous tissue in volume-based plans were recalculated using Acuros (AXB) and compared to the Anisotropic Analytical Algorithm (AAA) algorithm. For all treatment planning strategies, chest wall coverage (V90%) was maintained. As expected, superficial structures demonstrate significant loss in coverage. The largest difference observed in the most superficial 3 mm where V90% coverage is reduced from a mean (± standard deviation) of 95.1% (± 2.8) to 18.9% (± 5.6) for clinical field-based treatments with and without bolus, respectively. For volume-based planning, the subcutaneous tissue maintains a V90% of 90.5% (± 7.0) compared to the clinical field-based planning coverage of 84.4% (± 8.0). In all skin and subcutaneous tissue, the AAA algorithm underestimates the volume of the 90% isodose. Removing bolus results in minimal dosimetric differences in the chest wall and significantly lower skin dose while dose to the subcutaneous tissue is maintained. Unless the skin has disease involvement, the most superficial 3 mm is not considered part of the target volume. The continued use of the AAA algorithm is supported for the PMRT setting. [ABSTRACT FROM AUTHOR]

The magnetic field of a transverse MR-linac alters electron trajectories as the photon beam transits through materials, causing lower doses at flat entry surfaces and increased doses at flat beam-exiting surfaces. This study investigated the response of a MOSFET detector, known as the MOSkin™, for high-resolution surface and near-surface percentage depth dose measurements on an Elekta Unity. Simulations with Geant4 and the Monaco treatment planning system (TPS), and EBT-3 film measurements, were also performed for comparison. Measured MOSkin™ entry surface doses, relative to Dmax, were (9.9 ± 0.2)%, (10.1 ± 0.3)%, (11.3 ± 0.6)%, (12.9 ± 1.0)%, and (13.4 ± 1.0)% for 1 × 1 cm2, 3 × 3 cm2, 5 × 5 cm2, 10 × 10 cm2, and 22 × 22 cm2 fields, respectively. For the investigated fields, the maximum percent differences of Geant4, TPS, and film doses extrapolated and interpolated to a depth suitable for skin dose assessment at the beam entry, relative to MOSkin™ measurements at an equivalent depth were 1.0%, 2.8%, and 14.3%, respectively, and at a WED of 199.67 mm at the beam exit, 3.2%, 3.7% and 5.7%, respectively. The largest measured increase in exit dose, due to the electron return effect, was 15.4% for the 10 × 10 cm2 field size using the MOSkin™ and 17.9% for the 22 × 22 cm2 field size, using Geant4 calculations. The results presented in the study validate the suitability of the MOSkin™ detector for transverse MR-linac surface dosimetry. [ABSTRACT FROM AUTHOR]

Introduction: Intraoperative electron radiation therapy (IOERT) is one of the most recently popular therapeutic methods for breast cancer. This study aimed to measure the skin dose near the applicator during IOERT of breast cancer patients, as well as, the incidence of acute toxicity after surgery. Materials and Methods: Thirty-six female patients participated in the current study with the prescribed dose of 21 and 12 Gy for IOERT as full and boost, respectively. The skin dose was investigated based on different applicator sizes, tumor bed thicknesses, and monitor units (MUs). The energy was chosen 8 MeV, and EBT3 film was used for the dosimetric process. In addition, the acute toxicity included healing time for the surgical wound, scaling of the skin, itching, necrosis, redness as well as seroma formation for 1 week and 1 month were recorded. The results were compared to those of 22 patients who underwent the surgery without IOERT. Results: The highest skin dose for the patients was obtained 2.09 Gy, which is lower than the threshold dose (6 Gy). Furthermore, the findings showed that the average skin dose was higher in bigger applicator sizes and MU and lower tumor bed thicknesses. The average of wound healing for the patient underwent IOERT and without the use of IOERT (as the control group) was 19.32 and 11.67 days, respectively. One month after surgery, the volume of aspirated seroma was higher in the patients who performed IOERT compared to the control group (250 ml vs. 200 ml). It is notable that there were not observed any redness, itching, scaling, and necrosis in both investigated groups. Conclusion: Owing to the results, the skin dose during IOERT was lower than the recommended level. The dose of IOERT as a full was higher than boost which can be related to the lower number of the patients in full method; however, there was a well-tolerated without severe acute complication, especially seroma formation and wound healing time in both full and boost methods. [ABSTRACT FROM AUTHOR]

Objective(s): The aim of this study was to determine the entrance skin dose distribution for breast cancer patients who undergo radiotherapy in the presence of bolus containing gold and Fe3O4 nanoparticles to evaluate and compare the changes in dose distribution. Materials and Methods: Gold and Fe3O4 nanoparticles can increase the rate of photoelectric, Compton, and pair production absorption of x-ray photons. Nanoparticles were simulated in the bolus, over the skin of a breast phantom, by the exertion of MCNPX Monte Carlo code. The skin dose was also experimentally measured by using a bolus that contained homogeneously distributed Fe3O4 nanoparticles on the surface of a slab phantom and an advanced Markus chamber. Results: A significant skin dose enhancement was obtained for the case that 25 nm gold and Fe3O4 nanoparticles with 3% concentration were uniformly distributed in the bolus. However, increased concentration of nanoparticles in the bolus will increase the skin dose. Conclusion: It is concluded that using nanoparticles in the bolus leads to a significant skin dose enhancement for 6 MV x-ray photons. Furthermore, this study suggested that, less thick blouses may provide the same dose distribution. [ABSTRACT FROM AUTHOR]

• Guidelines on skin superficial BT do not fully reflect the clinical practice of large tumors. • No dosimetry parameters-PROM relationships are found in skin cancer superficial BT. • Publications using constraints beyond recommendations meet excellent results. The aim of this publication is the assessment of the existing guidelines for non-melanoma skin cancer (NMSC) superficial brachytherapy (BT) and make a critical review based on the existing literature about the maximum dose prescription depth, bolus thickness and maximum skin surface dose (D max) of the published clinical practice. A systematic review of NMSC superficial BT published articles was carried out by the GEC-ESTRO Head & Neck and Skin (HNS) Working Group (WG). 10 members and 2 external reviewers compared the published clinical procedures with the recommendations in the current guidelines and examined the grade of evidence. Our review verified that there is a large variation among centres with regards to clinical practice in superficial BT and identified studies where published parameters such as maximum dose prescription depth, bolus thickness and D max exceed the constraints recommended in the guidelines, while showing excellent results in terms of local control, toxicity and cosmesis. This review confirmed that current recommendations on skin superficial BT do not include published experience on tumours treated with superficial BT that require dose prescription depth beyond the recommended 5 mm under the skin surface and that the existing literature does not provide sufficient evidence to relate dosimetry of superficial BT to patient reported outcome measures. The GEC-ESTRO HNS WG considers acceptable to prescribe superficial BT dose at a depth above 5 mm beyond the skin surface, and modify the bolus thickness to optimize the treatment plan and adjust the acceptable maximum dose on the skin surface, all pending clinical situation. [ABSTRACT FROM AUTHOR]

Objectives The study aim was to analyse the influence of the lead free cap on doses received by interventional cardiologists. The impact of lead free cap on doses to the head were evaluated in number of studies. As different methods used to assess the attenuation properties of protective cap can lead to ambiguous results, a detailed study was performed. Material and Methods The effectiveness of a lead free cap in reducing the doses to the skin was assessed in clinic by performing measurements with thermoluminescent dosimeters attached inside and outside the cap first during individual coronary angiography (CA) or CA/percutaneous transluminal coronary angioplasty (CA/PTCA) procedures and then cumulated during few procedures of the same type. In order to investigate the effect of the cap on reducing the doses to the brain additional measurements were performed with a male Alderson Rando and polymethyl methacrylate (PMMA) phantoms representing the physician and the patient, respectively for different projections. The brain dose per procedure, annual and cumulated during entire working practice were estimated for both cases working with and without the cap. Results The dose reduction factor (RF) for the skin (the quotient of doses outside and inside the cap) vary from 1.1 up to 4.0 in clinical conditions; on average 2.3-fold reduction is observed in the most exposed left temple. The RFs determined for the part of the head covered by the cap range from 1.4 to 1.8 while for the brain from 1.0 to 1.1 depending on the projection. The estimated annual brain dose for interventional cardiologist performing yearly 550 CA/PTCA procedures without any protective shields is 7.2 mGy and it is reduced with the lead free cap by an average factor of 1.1. Conclusions The study results proved the considerable effectiveness of lead free cap to protect the skin but very limited to protect the brain. Int J Occup Med Environ Health. 2022;35(5):549–60

Breast cancer is the most common cancer for incidence and mortality among females globally and in Indonesia. Mastectomy is still the most common surgery for female breast cancer in Indonesia. After the mastectomy, several patients will receive a whole breast radiotherapy session. About 68.75% of breast cancer patients in the radiotherapy department at Lavalette Hospital during 2019 had undergone the mastectomy. Radiotherapy treatment for breast cancer can be delivered using Intensity Modulated Radiotherapy (IMRT) or 3D-Conformal Radiotherapy (3DCRT) technique. This study is aimed to compare the skin dosimetric between IMRT and 3DCRT for post-mastectomy breast radiotherapy. Left-sided breast cancer patients who underwent radiotherapy at Lavalette Hospital during 2019 were included in this study, and 15 patients were selected. All patients received 50 Gy in 25 fractions over 5 weeks using 6 MV photons. The planning target volume (PTV) and organ at risk (OAR) were delineated. Skin with 3 mm thickness along PTV was also contoured for evaluating the dose delivered to the skin. The treatment planning was conducted using 3DCRT and 5 fields IMRT planning. The plans were optimized for at least 95% of the prescribed dose to cover 95% volume of the PTV. The mean dose and maximum dose were used for evaluating and comparing each plan. The skin’s mean dose from 3DCRT planning was 24.65 ± 4.12 Gy and 22.85 ± 3.68 Gy (p = 0.002) for IMRT planning. Meanwhile, skin maximum doses were 54.15 ± 0.68 Gy and 53.89 ± 1.05 Gy (p = 0.001) respectively for 3DCRT and IMRT planning. These results showed that IMRT offered a lower dose to the skin and a better skin-sparing effect than 3DCRT.

A miniature electronic X-ray source was employed in this study to deliver intra-operative radiotherapy (IORT) within breast lesions. A flexible magnetic material was used to reduce breast skin radiation damage. Total prescribed dose was 20 Gy at balloon surface, with breast tumor bed wrapped around balloon applicator. A flexible magnetic material, called ‘neodymium-iron boron’ (NdFeB) + alloy-49 was applied to cover lesion’s surface to preserve the skin and to reduce electron contamination raised from photon-induced low-energy electrons, with tissue less than 1 cm between applicator surface and breast skin. The reduction of electron contamination using NdFeB + alloy-49 with an applicator-skin distance of 20 mm, ranged from 7% to 10%, while with an applicator-skin distance of 10 mm for balloon volumes from 30 to 50 cm3, it ranged from 4% to 6% only. NdFeB + alloy-49 magnetic material was efficient in repulsing photon-induced low-energy electrons for skin preservation to compensate for deficiency of tissue over less than 1 cm gap between the surface of applicator and the breast skin.

Introduction: Magnetic resonance imaging-linear accelerator radiotherapy is an innovative technology that requires special consideration for secondary electron interactions within the magnetic field, which can alter dose deposition at air–tissue interfaces. As part of ongoing quality assurance and quality improvement of new radiotherapy technologies, the purpose of this study was to evaluate skin dose modelled from the treatment planning systems of a magnetic resonance imaging-linear accelerator and a conventional linear accelerator, and then correlate with in vivo measurements of delivered skin dose from each linear accelerator. Methods: In this prospective cohort study, 37 consecutive glioma patients had treatment planning completed and approved prior to radiotherapy initiation using commercial treatment planning systems: a Monte Carlo-based algorithm for magnetic resonance imaging-linear accelerator or a convolution-based algorithm for conventional linear accelerator. In vivo skin dose was measured using an optically stimulated luminescent dosimeter. Results: Monte Carlo-based magnetic resonance imaging-linear accelerator plans and convolution-based conventional linear accelerator plans had similar dosimetric parameters for target volumes and organs-at-risk. However, magnetic resonance imaging-linear accelerator plans had 1.52 Gy higher mean dose to air cavities (P <.0001) and 1.10 Gy higher mean dose to skin (P <.0001). In vivo skin dose was 14.5% greater for magnetic resonance imaging-linear accelerator treatments (P =.0027), and was more accurately predicted by Monte Carlo-based calculation (ρ = 0.95, P <.0001) versus convolution-based (ρ = 0.80, P =.0096). Conclusion: This is the first prospective dosimetric comparison of glioma patients clinically treated on both magnetic resonance imaging-linear accelerator and conventional linear accelerator. Our findings suggest that skin doses were significantly greater with magnetic resonance imaging-linear accelerator plans but correlated better with in vivo measurements of actual skin dose from delivered treatments. Future magnetic resonance imaging-linear accelerator planning processes are being designed to account for skin dosimetry and treatment delivery. [ABSTRACT FROM AUTHOR]

Objectives: The study aim was to analyse the influence of the lead free cap on doses received by interventional cardiologists. The impact of lead free cap on doses to the head were evaluated in number of studies. As different methods used to assess the attenuation properties of protective cap can lead to ambiguous results, a detailed study was performed.Material and Methods: The effectiveness of a lead free cap in reducing the doses to the skin was assessed in clinic by performing measurements with thermoluminescent dosimeters attached inside and outside the cap first during individual coronary angiography (CA) or CA/percutaneous transluminal coronary angioplasty (CA/PTCA) procedures and then cumulated during few procedures of the same type. In order to investigate the effect of the cap on reducing the doses to the brain additional measurements were performed with a male Alderson Rando and polymethyl methacrylate (PMMA) phantoms representing the physician and the patient, respectively for different projections. The brain dose per procedure, annual and cumulated during entire working practice were estimated for both cases working with and without the cap.Results: The dose reduction factor (RF) for the skin (the quotient of doses outside and inside the cap) vary from 1.1 up to 4.0 in clinical conditions; on average 2.3-fold reduction is observed in the most exposed left temple. The RFs determined for the part of the head covered by the cap range from 1.4 to 1.8 while for the brain from 1.0 to 1.1 depending on the projection. The estimated annual brain dose for interventional cardiologist performing yearly 550 CA/PTCA procedures without any protective shields is 7.2 mGy and it is reduced with the lead free cap by an average factor of 1.1.Conclusions: The study results proved the considerable effectiveness of lead free cap to protect the skin but very limited to protect the brain. Int J Occup Med Environ Health. 2022;35(5):549-60. [ABSTRACT FROM AUTHOR]

Many radiation planning techniques have been used to increase dose to the vulvar surface when treating patients with vulvar cancer with volumetric modulated arc therapy. Target volumes near the skin surface, such as vulvar tumors, do not meet the International Commission on Radiation Units and Measurements safety guidelines. Without the needed expansions and setup uncertainties, there are concerns that treated dose to the vulvar surface varies from the planned dose. The purpose of this study was to determine if the robust optimization tool used in volumetric modulated arc therapy planning can reproducibly deliver prescription dose to the vulvar skin surface despite setup uncertainties and reduced safety margins. To further mitigate the possibilities of setup errors and dose variation to the vulvar surface, robust optimization during planning must be considered. For this case study, 5 patients with similar diagnoses and vulvar surface dose requirements were retrospectively replanned using robust optimization. An evaluation structure was created representing the vulvar surface for each patient. This structure was assigned robustness characteristics. After multiple optimizations and planning scenarios, perturbed dose representing dataset shifts were evaluated along the vulvar surface. Every patient met minimal metrics of 100% of vulvar surface volume receiving 95% of the prescription dose. An additional review of 95% of vulvar surface volume receiving 100% of the prescription dose showed similar results. Robust optimization can be used in the planning process to mitigate setup uncertainties. [ABSTRACT FROM AUTHOR]

Purpose: The aim of this study is to investigate off‐axis irradiation on the Australian MRI‐Linac using experiments and Monte Carlo simulations. Simulations are used to verify experimental measurements and to determine the minimum offset distance required to separate electron contamination from the photon field. Methods: Dosimetric measurements were performed using a microDiamond detector, Gafchromic® EBT3 film, and MOSkinTM. Three field sizes were investigated including 1.9 × 1.9, 5.8 × 5.8, and 9.7 × 9.6 cm2. Each field was offset a maximum distance, approximately 10 cm, from the central magnetic axis (isocenter). Percentage depth doses (PDDs) were collected at a source‐to‐surface distance (SSD) of 1.8 m for fields collimated centrally and off‐axis. PDD measurements were also acquired at isocenter for each off‐axis field to measure electron contamination. Monte Carlo simulations were used to verify experimental measurements, determine the minimum field offset distance, and demonstrate the use of a spoiler to absorb electron contamination. Results: Off‐axis irradiation separates the majority of electron contamination from an x‐ray beam and was found to significantly reduce in‐field surface dose. For the 1.9 × 1.9, 5.8 × 5.8, and 9.7 × 9.6 cm2 field, surface dose was reduced from 120.9% to 24.9%, 229.7% to 39.2%, and 355.3% to 47.3%, respectively. Monte Carlo simulations generally were within experimental error to MOSkinTM and microDiamond, and used to determine the minimum offset distance, 2.1 cm, from the field edge to isocenter. A water spoiler 2 cm thick was shown to reduce electron contamination dose to near zero. Conclusions: Experimental and simulation data were acquired for a range of field sizes to investigate off‐axis irradiation on an inline MRI‐Linac. The skin sparing effect was observed with off‐axis irradiation, a feature that cannot be achieved to the same extent with other methods, such as bolusing, for beams at isocenter. [ABSTRACT FROM AUTHOR]

Abstract Background The dose perturbation effect of immobilization devices is often overlooked in intensity-modulated radiation therapy (IMRT) for breast cancer (BC). This retrospective study assessed the dosimetric effects of supine immobilization devices on the skin using a commercial treatment planning system. Methods Forty women with BC were divided into four groups according to the type of primary surgery: groups A and B included patients with left and right BC, respectively, who received 50 Gy radiotherapy in 25 fractions after radical mastectomy, while groups C and D included patients with left and right BC, respectively, who received breast-conservation surgery (BCS) and 40.05 Gy in 15 fractions as well as a tumor bed simultaneous integrated boost to 45 Gy. A 0.2-cm thick skin contour and two sets of body contours were outlined for each patient. Dose calculations were conducted for the two sets of contours using the same plan. The dose differences were assessed by comparing the dose-volume histogram parameter results and by plan subtraction. Results The supine immobilization devices for BC resulted in significantly increased skin doses, which may ultimately lead to skin toxicity. The mean dose increased by approximately 0.5 and 0.45 Gy in groups A and B after radical mastectomy and by 2.7 and 3.25 Gy in groups C and D after BCS; in groups A–D, the percentages of total normal skin volume receiving equal to or greater than 5 Gy (V5) increased by 0.54, 1.15, 2.67, and 1.94%, respectively, while the V10 increased by 1.27, 1.83, 1.36, and 2.88%; the V20 by 0.85, 1.87, 2.76, and 4.86%; the V30 by 1.3, 1.24, 10.58, and 11.91%; and the V40 by 1.29, 0.65, 10, and 10.51%. The dose encompassing the planning target volume and other organs at risk, showed little distinction between IMRT plans without and with consideration of immobilization devices. Conclusions The supine immobilization devices significantly increased the dose to the skin, especially for patients with BCS. Thus, immobilization devices should be included in the external contour to account for dose attenuation and skin dose increment. Trial registration This study does not report on interventions in human health care.

The Australian MRI-Linac prototype radiotherapy system has been shown to generate significant entry skin or surface dose increases. This arises from electron contamination focusing toward the isocenter caused by the 1 T MRI field being in-line with the x-ray beam. The aim of this study is to present accurate Monte Carlo modeling of these skin dose changes and to compare them with previous experimental measurements. Accurate skin dose modeling will improve confidence in the pathway forward to treatment planning for clinical trials. A COMSOL Multiphysics model of the Australian MRI-Linac system was used to generate a 3D magnetic field map to be used in corresponding Geant4 Monte Carlo simulations. The Geant4 simulations included the x-ray source (6 MV Linac), multileaf collimators (MLCs), and a 30 cm × 30 cm × 30 cm water phantom located with its front surface at the beam isocenter. Simulations were performed with a source to surface distance (SSD) of 1,819 mm for nominal field sizes 2 cm × 2 cm, 6 cm × 6 cm, and 10 cm × 10 cm. Central axis percentage depth dose (PDD) and surface (or skin) doses at 70 μm depth were calculated by using high-resolution scoring voxels of 10 μm thickness. The results were compared with corresponding experimental data collected using MOSkin™ on the Australian MRI-Linac prototype system. The accurate modeling provides great detail into how the electron contamination is heavily confined and focused toward the beam central axis due to the presence of in-line magnetic field. This concentration significantly increases the skin dose up to 320% for the field size of 10 cm × 10 cm. For 2 cm × 2 cm and 6 cm × 6 cm, the surface skin dose is 128% and 217%, respectively, as compared to the skin dose in the absence of the magnetic field. The simulation results are in generally good agreement, ±10%, with previously collected experimental data for the same nominal field sizes. For the first time, detailed Geant4 Monte Carlo simulations of the electron contamination in the Australian MRI-Linac system have been performed and confirmed to be sufficiently accurate. These simulations will provide a solid framework for estimating the skin dose changes in more clinically relevant treatment plan scenarios that are envisaged in the near future.

The aim of this study is to investigate the skin dose of total body irradiation (TBI) with Helical Tomotherapy and the need to use a bolus to achieve an adequate skin dose. To simulate the RANDO phantom geometrically, arms and legs created from rice were added to the RANDO phantom and it was immobilized in a vacuum bed. Computed tomography (CT) images of the lower and upper parts of the phantom with a slice thickness of 3 mm were acquired with and without bolus. Fifteen thermoluminescent dosimeters (TLDs) were placed on the skin line of the RANDO phantom. Treatment plans were prepared, and the phantom was irradiated both with and without bolus by the Helical Tomotherapy technique. Results of the measurements and treatment planning system (TPS) doses were compared by the non-parametric Wilcoxon signed-rank test. All procedures were repeated three times and results were evaluated. At the end of the study, it was proven that even when no bolus is used, the skin receives an adequate dose in TBI with Helical Tomotherapy while achieving homogeneous dose distribution and saving critical organs at the same time. • The skin dose in TBI should not be under 90% of the given dose. • The skin-sparing effect of the photon beam is not desired in TBI. • In old TBI techniques beam spoiler or bolus is needed to reach desired skin dose. • In Tomotherapy, there is no need to use a bolus to enhance the skin dose. • TLD is an important part of treatment planning and QA in radiation therapy for TBI. [ABSTRACT FROM AUTHOR]

For postmastectomy radiation therapy (PMRT), it is extremely important that the chest wall skin receives adequate dose. The aim of this prospective study was to evaluate the effect of bolus in breast cancer patients treated with 3D conformal radiotherapy (3D-CRT) and intensity-modulated radiotherapy (IMRT) techniques by in vivo dosimetry. The study included 20 mastectomized breast cancer patients. Nine different points were marked on the chest wall surface of the patients before computed tomography (CT). It was ensured that the dose reading points were the same in treatment planning system (TPS) and in-vivo measurements. Half of the patients in the study group were treated with IMRT and the other half with 3D-CRT technique. 3D-CRT and IMRT patients were planned to be treated with bolus every other day. Dose distributions for the presence and absence of bolus were obtained from the chest wall skin of each patient. In in-vivo dose measurements in IMRT patients, the mean skin dose without bolus was 152.06 cGy, while the mean skin dose increased to 213.95 cGy with the use of bolus. In the 3D-CRT technique, the mean chest wall dose in TPS was 146.78 cGy and 201.1 cGy for non-bolus and bolus plans, respectively. For both treatment techniques, the skin dose calculated by TPS was lower than in-vivo dose measurements. In this study, it was observed that the use of bolus increased the skin dose sufficiently. It was also observed that skin doses were more homogeneous in 3D-CRT technique than IMRT technique. It was observed that TPS has significant deficiencies in dose calculation in the evaluation of skin doses in breast radiotherapy, therefore, it is recommended to use in-vivo dosimetric methods for control. • There are limited number of literature studies prospectively evaluating the effect of bolus on skin dose for PMRT. • The chest wall surface must receive the required dose to prevent recurrences in PMRT. • Bolus material is widely used in PMRT. • In vivo dosimetry is extremely important for 3D-CRT and IMRT in breast radiotherapy. [ABSTRACT FROM AUTHOR]

In treatments such as post-mastectomy radiation therapy (PMRT) for breast cancer patients, skin doses are of great importance in terms of tumor control and side effects. This dosimetric study aimed to measure the skin dose on the chest wall surface for post-mastectomy radiotherapy with Tomotherapy and Halcyon devices using thermoluminescence dosimetry (TLD) and to evaluate the accuracy of the skin dose calculated by treatment planning systems (TPS). Computed tomography (CT) images of the Alderson Rando phantom were obtained. Treatment plans were created with Tomotherapy and Halycon devices for a total of 50 Gy with a fraction dose of 2 Gy to the target volume. The left chest wall was divided into 9 regions for detailed surface dose assessment. 88 dose measurement points were determined on the left chest wall. The phantom was irradiated separately in Halycon and Tomotherapy devices. In vivo, dose measurements were performed with TLD in both devices. TPS and TLD doses were compared for the left chest wall surface. For skin dose, TLD measurements were lower than the dose estimate by Tomotherapy TPS and higher than the dose estimate by Halycon TPS. In addition, the skin dose measurements showed that the skin dose of the Tomotherapy device was higher than that of the Halycon. It is recommended to consider the distance of the treatment device and the accuracy of the TPS dose calculation in skin dose assessment in PMRT. • Comparison of skin dose on the chest wall surface for PMRT with tomotherapy and Halcyon. • Thermoluminescence dosimetry (TLD) results were compared with treatment planning systems (TPS). • TLD doses were higher than TPS doses of both devices. • In PMRT, the skin dose of the Tomotherapy device was higher than Halycon. [ABSTRACT FROM AUTHOR]

A parallel-plate ionization chamber (PPC) with a nominal volume of 8.16 cm³ was developed based on theoretically simulated design parameters. Its purpose is to serve as a transfer standard for dosimetry in a beta radiation field. The entrance window of the PPC consists of an aluminized Mylar sheet with a thickness of 1.4 mg/cm2. The collecting and guard electrodes are created by applying a graphite coating on a Poly Methyl Methacrylate (PMMA) substrate with a thickness of 5 mm. The nominal sheet resistance of the graphite-coated PMMA substrate was measured using a four-probe technique and found to be approximately 800 Ω per square (Ω/□). Dosimetric characterization of the PPC was performed in the ISO 6980 reference beta radiation field, utilizing 90Sr-90Y and 85Kr beta radiation sources. The assessment included studies on short-term stability, linearity, current-to-voltage characteristics, stabilization time, and leakage current. The PPC was calibrated and established as a transfer standard using the 'Extrapolation Ionization Chamber,' recognized as an absolute standard for dose to tissue in 90Sr-90Y and 85Kr beta sources within the laboratory. The calibration coefficient of the PPC indicates an energy dependence of 0.6 % for 90Sr-90Y and 85Kr beta sources. • A parallel plate ionization chamber (PPC) of volume 8.16 cm3 is developed as per simulated design parameters. • Dosimetric characterization of this PPC is carried out for leakage current, stability, stabilization time and linearity etc. • Reference beta radiation field from 85Kr and 90Sr/90Y are standardized by absolute standard extrapolation ionization chamber. • Calibration of the newly developed PPC to establish it as transfer standard for dosimetry of beta particles field. [ABSTRACT FROM AUTHOR]

Aim: To evaluate clinically pertinent skin dose and volume parameters for the development of toxicities following accelerated partial breast irradiation (APBI). Methods: Three skin structures of various thicknesses inside the body (2 mm, 3 mm, 4 mm) were contoured over the treated breast retrospectively in a cohort of 62 women who underwent APBI using multi-catheter interstitial brachytherapy. The correlation statistics between the various skin structures and acute and late skin sequelae were evaluated using the Mann–Whitney U test and receiver-operating characteristic analysis. A p-value of <0·05 was considered significant. Results: At a median follow-up period of 54 months (range: 28–86), a significant correlation was seen between dose received by 0·2 (D0·2) cc of skin 4 mm inside the body as well as volume receiving 100% dose (V100) of skin 3 mm inside the body with cosmesis at 2 years and at last follow-up. The threshold for the two parameters for prediction of excellent or good cosmesis was 90% of the prescribed dose and 0·05 cc, respectively. No significant dosimetric or volumetric correlation was seen with other sequelae like wound dehiscence, fat necrosis, telangiectasia and atrophy. Conclusion: The results of this study support the use of dose and volumetric indices of the sub-volumes of the skin for correlation with clinical endpoints. However, the same should be validated prospectively in a larger cohort of women undergoing breast brachytherapy. [ABSTRACT FROM AUTHOR]

Background: Previous studies have discussed the diagnostic value of four dimensional kinematic CT in cases of carpal instabilities. This analysis compares calculated skin doses of 4D CT and conventional cineradiography of the wrist in cases of suspected SLL rupture. Methods: Retrospective calculation and interpolation of skin doses and effective doses for ten consecutive 4D CT examinations and 41 cineradiographies for suspected lesions of the scapholunate ligament. Standardised anterior-posterior and lateral cine sequences using a flat-panel digital subtraction imager and of 4D kinematic CT using a dual-source scanner were acquired and acquisition parameters recorded. We tested if the skin dose of 4D CT is different from cineradiography. Results: Median dose area product (DAP) of cineradiography was 135.34 cGycm2 resulting in a calculated median skin dose of 32.6 mSv (confidence interval 26.86–42.90 mSv) and an estimated effective skin dose of 3.26 µSv. CT dose index (CTDI) for 4D examinations was recorded to be 26.79 mGy and the dose-length product (DLP) was 150 mGy × cm. This resulted in an estimated skin dose of 34 mSv, which is covered by the confidence interval of cineradiography, and an effective skin dose of 3.4 µSv. Conclusions: Skin dose calculations are comparable for 2D cineradiography in two plains and 4D kinematic CT of the wrist. Calculated effective doses are < 0.01 mSv. [ABSTRACT FROM AUTHOR]

Skin-care cream is commonly applied to relieve skin redness in radiotherapy. However, using cream on the patient under the photon field would increase the skin dose in delivery. The aim of this study is to evaluate the dependences of skin dose enhancement on different beam and cream variables using Monte Carlo simulation. Using a solid water phantom with water-equivalent bolus, PMMA layer and cream layer, we irradiated it by 6 MV photon beams. Skin doses were calculated by varying the beam quality (flattening-filter (FF) and flattening-filter-free (FFF)), beam angle (0°–80°), skin-care cream type (water-based and silicon-based) and cream thickness (0–3 mm) using the EGSnrc Monte Carlo code. The densities of the water- and silicon-based cream were 0.92 and 1.14 g/cm 3 . The dose enhancement factor (DEF) defined as the ratio of the skin dose with skin-care cream to the skin dose without cream was calculated. It is found that the FF photon beam had higher DEF value than the FFF. For the water-based cream of 3 mm, the DEF for the FF beam was about 22.1% higher than that of the FFF. While for the silicon-based cream with the same thickness, the DEF was 24.2% higher. DEF value also increased with the beam angle. The DEF values were from 1.4 to 2.52 (water-based cream) and 1.42 to 2.68 (silicon-based cream) when the beam angle was increased from 20° to 80° using the 6 MV FF beams. Similarly, for the 6 MV FFF beams, the DEF values increased from 1.29 to 2.07 and 1.30 to 2.18 for the water- and silicon-based cream. These simulation results showed that the skin dose enhancement increased with an increase of beam angle, cream thickness, cream density, and the irradiation of FFF photon beams.

Introduction: The postmastectomy radiotherapy uses bolus to improve the coverage close to the skin; however, it needs to be removed in case of severe skin toxicity. This study investigated the effect of bolus parameters (i.e., frequency and thickness) for the superposition algorithm on skin dose in postmastectomy three-dimensional conformal radiotherapy (3D-CRT). Material and Methods: The present study was carried out ona total of 22 patients. First, all the plans were calculated without using bolus. Then, the plans were recalculated using different bolus frequencies (5, 10, 15, 20, 25) and thicknesses (0.5 and 1 cm). To evaluate the dose delivered to the skin, a 2-mm thick skin was profiled, and statistical analysis was performed by studying the dosimetric parameters (i.e., minimum, mean, and maximum) of chest wall skin. Results: The superficial coverage of planning target volume (PTV) was better by using bolus. In the case of skin, the bolus thickness had a significant impact on the minimum and mean doses for all bolus frequencies , while there was no significant effect on the maximum before 20-bolus frequency. The bolus frequency increase demonstrated a significant difference on all dosimetric parameters of the skin , except the maximum showed no significant difference between 0 and 5-bolus frequencies . Conclusion: The obtained results indicated that the bolus use had generally a significant effect on the chest wall skin dosimetric parameters depending on bolus frequency and thickness. Therefore, the choice of bolus frequency and bolus thickness can affect the clinical decisions in certain cases.

Objective. This study aimed to develop a new approach to predict radiation dermatitis (RD) by using the skin dose distribution in the actual area of RD occurrence to determine the predictive dose by grade. Approach. Twenty-three patients with head and neck cancer treated with volumetric modulated arc therapy were prospectively and retrospectively enrolled. A framework was developed to segment the RD occurrence area in skin photography by matching the skin surface image obtained using a 3D camera with the skin dose distribution. RD predictive doses were generated using the dose-toxicity surface histogram (DTH) calculated from the skin dose distribution within the segmented RD regions classified by severity. We then evaluated whether the developed DTH-based framework could visually predict RD grades and their occurrence areas and shapes according to severity. Main results. The developed framework successfully generated the DTH for three different RD severities: faint erythema (grade 1), dry desquamation (grade 2), and moist desquamation (grade 3); 48 DTHs were obtained from 23 patients: 23, 22, and 3 DTHs for grades 1, 2, and 3, respectively. The RD predictive doses determined using DTHs were 28.9 Gy, 38.1 Gy, and 54.3 Gy for grades 1, 2, and 3, respectively. The estimated RD occurrence area visualized by the DTH-based RD predictive dose showed acceptable agreement for all grades compared with the actual RD region in the patient. The predicted RD grade was accurate, except in two patients. Significance . The developed DTH-based framework can classify and determine RD predictive doses according to severity and visually predict the occurrence area and shape of different RD severities. The proposed approach can be used to predict the severity and shape of potential RD in patients and thus aid physicians in decision making., (© 2024 Institute of Physics and Engineering in Medicine.)

We investigated skin dose enhancements of brass mesh bolus (BMB) and a recently developed transparent polymer-gel bolus (PGB) for clinically relevant breast treatment delivery techniques. The dose enhancement of the breast surface with BMB and PGB were compared to that of tissue-equivalent bolus. Three breast treatment plans were generated on CT scans of an anthropomorphic chest phantom: tangential step-and-shoot 3D conformal (3DCRT) planned using Field-in-Field (FiF), tangential sliding-window 3DCRT using Electronic Compensator (EC), and volumetric modulated arc therapy (VMAT). All plans were created using 6 MV photons and a prescription dose (Rx) of 180 cGy per fraction. Skin doses of all 3 plans were measured with radiochromic films, separately delivered in triplicate. Each plan was delivered to the phantom without bolus, and then with BMB (1 or 2 layers; 3 or 10 mm tissue-equivalent), PGB, and Superflab (3, 5, and 10 mm tissue-equivalent). Doses were determined by reading the radiochromic films with a flatbed scanner, and analyzing the images using a calibration curve for each specific batch. For all bolus types and plans, surface doses averaged over the 3 measurements were between 88.4% and 107.4% of Rx. Without bolus, average measured skin doses were between 51.2% and 64.2% of Rx. Skin doses with BMB and PGB were comparable to that with tissue-equivalent bolus. Over all 3 treatment delivery techniques, using BMB resulted in average skin doses of 92.8% and 102.1% for 1- and 2 layers, respectively, and using PGB results in average skin doses of 94.8%, 98.2%, and 99.7% for 3, 5, and 10-mm tissue-equivalent, respectively. The average measured skin doses with BMB and PGB agreed within ± 3% compared to the tissue-equivalent thickness bolus. We concluded that BMB and PGB are clinically equivalent in skin dose enhancement for breast treatment as the 3, 5, and 10 mm tissue-equivalent bolus. [ABSTRACT FROM AUTHOR]

Purpose: To measure and compare the skin doses received by treated left breast and contralateral breast (CB) during whole breast radiotherapy using five treatment techniques in an indigenously prepared wax breast phantom. Materials and methods: Computed tomography (CT) images of the breast phantom were used for treatment planning and comparison of skin dose calculated from treatment planning system (TPS) with measured dose. Planning target volume (PTV) and the CB were drawn arbitrarily on the CT images acquired for the breast phantom with 10 numbers of calibrated optically stimulated luminescent dosimeters (OSLDs) fixed on the surface of both breasts. The TPS calculated surface doses of PTV breast and CB for five treatment planning techniques, viz., conventional wedge (CW), irregular surface compensator-based (ISC), field-in-field (FiF), intensity-modulated radiotherapy (IMRT) and rapid arc (RA) techniques were obtained for comparison. The plans were executed in Clinac iX Linear Accelerator with the OSLDs fixed at the same locations on the phantom as in simulation. The TPS calculated mean dose at the surface of the treated left breast and CB was noted for the 10 OSLDs from dose-volume histogram (DVH) and compared with the measured dose. Also, the mean chamber dose at the centre of the left breast was noted from the DVH for comparing with ion chamber measured dose. Results: With reference to the results, it is seen that the dose to the CB is lowest in ISC technique and FiF technique and greatest in IMRT technique. The CW technique also delivered a dose comparable to IMRT to the CB of the phantom. The dose to the surface of PTV breast was highest and comparable in CW plans and FiF plans (68% and 67%) and lowest in IMRT and RA plans (50% each). Findings: Analysis of the results shows that the FiF and ISC techniques are preferred while planning breast radiotherapy due to the reduced dose to the CB. [ABSTRACT FROM AUTHOR]

This study aims at the estimation of skin doses during small field radiotherapy with 6 MV photons and analysis of beam spectra at skin surface. The EGSnrc Monte Carlo code was used for spectral analysis and dose scoring in a water phantom. Percent skin dose (PSD) was calculated at a depth of 70 µm (relative to 10 cm depth), and the effects of field size, collimation, source-to-surface distance, and tissue inhomogeneity (bone/air) below the skin were evaluated. Low-energy photons and contaminant electrons from the machine head or back-scattered from underlying tissue were found to be the major contributors to skin dose. As the field size was reduced, the beam hardened, while the photon and electron fluences at the skin decreased compared to those at the reference depth of 10 cm. This resulted in a PSD reduction for fields smaller than the reference field size. Multi leaf collimators increased the PSD (up to 4%) while variation in source-to-skin dose showed a negligible effect. A substantial increase in PSD has been observed (up to 6%) when high Z material like bone was placed below the skin. In contrast, air as underlying material decreased the skin dose. The skin dose varied considerably with various clinical and geometric parameters. It is concluded that, although the skin doses were low for small fields compared to those for the reference field, skin doses may become substantial when escalated target doses are delivered with multi leaf collimators. Moreover, the presence of high Z materials such as bones or metallic implants below the skin can result in significant enhancement of the skin dose. [ABSTRACT FROM AUTHOR]

Background: The dose perturbation effect of immobilization devices is often overlooked in intensity-modulated radiation therapy (IMRT) for breast cancer (BC). This retrospective study assessed the dosimetric effects of supine immobilization devices on the skin using a commercial treatment planning system.Methods: Forty women with BC were divided into four groups according to the type of primary surgery: groups A and B included patients with left and right BC, respectively, who received 50 Gy radiotherapy in 25 fractions after radical mastectomy, while groups C and D included patients with left and right BC, respectively, who received breast-conservation surgery (BCS) and 40.05 Gy in 15 fractions as well as a tumor bed simultaneous integrated boost to 45 Gy. A 0.2-cm thick skin contour and two sets of body contours were outlined for each patient. Dose calculations were conducted for the two sets of contours using the same plan. The dose differences were assessed by comparing the dose-volume histogram parameter results and by plan subtraction.Results: The supine immobilization devices for BC resulted in significantly increased skin doses, which may ultimately lead to skin toxicity. The mean dose increased by approximately 0.5 and 0.45 Gy in groups A and B after radical mastectomy and by 2.7 and 3.25 Gy in groups C and D after BCS; in groups A-D, the percentages of total normal skin volume receiving equal to or greater than 5 Gy (V5) increased by 0.54, 1.15, 2.67, and 1.94%, respectively, while the V10 increased by 1.27, 1.83, 1.36, and 2.88%; the V20 by 0.85, 1.87, 2.76, and 4.86%; the V30 by 1.3, 1.24, 10.58, and 11.91%; and the V40 by 1.29, 0.65, 10, and 10.51%. The dose encompassing the planning target volume and other organs at risk, showed little distinction between IMRT plans without and with consideration of immobilization devices.Conclusions: The supine immobilization devices significantly increased the dose to the skin, especially for patients with BCS. Thus, immobilization devices should be included in the external contour to account for dose attenuation and skin dose increment.Trial Registration: This study does not report on interventions in human health care. [ABSTRACT FROM AUTHOR]

In postmastectomy radiation therapy (PMRT), the adequate skin surface dose remains a problem. In this study, the effect of different CTV shrinkage and Skin flash margins on skin dose was investigated, and the accuracy of skin surface dose calculated by TPS for PMRT using thermoluminescent dosimeters (TLDs) was evaluated. Eighty-eight measurement points were determined on the Alderson Rando phantom. To determine the effects of shrinkage margin on skin dose, separate CTVs were generated for 2 mm, 3 mm and 5 mm shrinkage. The prescribed dose was 50 Gy to CTV with a daily fraction dose of 2 Gy. A total of 12 plans were created using four different skin flash thicknesses for each CTV shrinkage margin. After applying 0 mm, 10 mm, 15 mm and 20 mm skin flash thicknesses for each area of the 7F-IMRT treatment plan, the plans were recalculated, and the SF-0, SF-10, SF-15 and SF-20 plans were created, respectively. The increase in skin flash thickness in IMRT plans resulted in a significant increase in skin dose. There was a significant difference between TPS and TLD doses in all chest wall areas for SF-0, SF-10, and SF-15 (p < 0.05). However, there was no significant difference in all areas of the chest wall for SF-20 (p > 0.05). The shrinkage margin thickness of the CTV was found to be inversely proportional to the skin dose for all treatment plans. In tumors near the surface, bolus or skin flash techniques can get the skin adequately dosed. However, the skin flash technique has shown superiority in the application. In PMRT, it is recommended to keep the shrinkage margin as small as possible and use the skin flash thickness of 20 mm for the skin to receive a sufficient dose. • TLDs are common dosimeters for skin dose measurement. • Skin dose is very important in breast radiotherapy. • It is important to measure skin dose with TLDs during adaptive radiotherapy. • There is no literature study on shrinkage margin and skin-to-flash techniques in breast radiotherapy. [ABSTRACT FROM AUTHOR]

Use of diagnostic reference levels (DRLs) is an important tool for patient dose optimization in interventional radiology. DRLs are normally expressed in terms of kerma-area product (Pka). However, no direct method is available to estimate the probability of skin reactions using system displayed quantities. The aim of this work was to measure skin entrance doses (SEDs) in patients undergoing coronary angiography (CA) and percutaneous coronary interventions (PCI) using Gafchromic films and establish DRLs. The details of patients, exposure parameters, and dose quantities were recorded for 572 patients. Out of these, skin doses were measured for selected 64 patients using Gafchromic film. Measured SEDs are in the range of 48.2–740 mGy and 84–1242 mGy for CA and PCI, respectively. The data of 572 patients were analyzed, and 75th percentile of Pkawas calculated. DRLs for CA and PCI in terms of Pkaare found to be 34 and 134 Gy.cm2, respectively. DRLs for CA and PCI in terms of cumulative air kerma (Ka) at reference point are found to be 590 mGy and 1930 mGy, respectively. SED has a good correlation with Ka, however, it does not correlate well with Pka.

Abstract Background and purpose We created a scoring system incorporating dosimetric and clinical factors to assess the risk of severe, acute skin reactions in patients undergoing intensity-modulated radiation therapy (IMRT) to treat head and neck cancer (HNC). Materials and methods A total of 101 consecutive patients who received definitive IMRT or volumetric modulated arc therapy (VMAT) with a prescription dose of 70 Gy to treat HNC between 2013 and 2017 in our hospital were enrolled. Skin V5Gy, V10Gy, V20Gy, V30Gy, V40Gy, V50Gy, and V60Gy values delivered 5 mm within the body contour were compared between patients with Grades 1–2 and Grade 3 dermatitis. A scoring system was created based on logistic regression analysis (LRA) that identified the most significant dosimetric and clinical factors. Results The V60Gy was significantly associated with radiation dermatitis grade in both LRA and recursive partitioning analysis (RPA). A scoring system incorporating the V60Gy, concurrent chemotherapy status, age, and body mass index was used to divide all patients into three subgroups (0–1, 2–3, and 4–6 points) in the RPA. The incidence of Grade 3 dermatitis significantly differed among the subgroups (0, 20.5, and 58.6%, respectively, P

This study aimed to evaluate the relationship between the peak skin dose (PSD) associated with radiation skin injury and the fluoroscopic pulse rate or target vessel during percutaneous coronary intervention (PCI) procedures. We consecutively included 213 patients who underwent PCI procedures. The fluoroscopic time (FT), total number of cine frames, reference air kerma (RAK), and PSD were compared between the two types of fluoroscopic pulse rates (10 and 7.5 pulses/s) and among target vessels. The total number of X-ray tube angulations for each target vessel was also investigated. The median FT was 21.5 min in the 10 pulses/s group and 19.4 min in the 7.5 pulses/s group (p = 0.068, Wilcoxon rank sum test). The median PSD in the 10 pulses/s group was 749 mGy, which was significantly higher than that in the 7.5 pulses/s group (549 mGy) (p < 0.001). The median RAK in the right coronary artery (RCA) was equivalent to that in the left anterior descending artery. However, among the target vessels, the median PSD tended to be the highest in the RCA. There was a difference in the X-ray tube angulation used depending on the target vessel. PCI in the RCA used the left anterior oblique angle more frequently than PCI in the other vessels and tended to use only one angulation. The calculated PSD was related to the target vessel of the PCI procedure, and it was also closely related to the X-ray tube angulation. [ABSTRACT FROM AUTHOR]

Objective: Side effects of radiation therapy may include skin damage. The surface dose is of great interest and contains the buildup effect. In particular, the proton therapy community requires further experimental data to quantify doses in the surface region. This specification includes the skin dose, which is defined according to ICRU Report No. 39 at 70 μm water equivalent depth. The aim of this study is to gather more knowledge of the skin dose by varying key parameters defined by the patient treatment plan. This consists of clinical aspects such as the influence of the air gap, the application of a range shifter (RS), or the proton delivery technique. Material/methods: Skin doses were determined with a PTW 23391 extrapolation chamber with three thin Kapton® entrance windows operated as a conventional ionization chamber. The impact on the skin dose for quasi‐monoenergetic pencil beam scanning (PBS) proton beams was evaluated for clinical air gaps between 3.5 and 51.1 cm. The differences in skin dose were assessed by irradiating equivalent fields with an RS of 51 mm water equivalent thickness (RS51) and without. Furthermore, the delivery techniques PBS, uniform scanning (US), and double scattering (DS) were compared by defining a spread‐out Bragg peak (SOBP). TOPAS (V.3.1.2) was used to model an IBA nozzle with PBS and to score dose to water at the surface of a water phantom. Results: For the monoenergetic fields without the application of the RS the skin dose was constant down to an air gap of 6.2 cm. A lower air gap of 3.5 cm showed a variation in skin dose by up to 2.4% compared to the results obtained with larger air gaps. With the inserted RS51 an increase in the skin dose was found for air gaps smaller than 11.3 cm. Experimentally, a dose difference of 1.4% was recorded for an air gap of 6.2 cm by inserting an RS and none. With the Monte Carlo calculations the largest dose increase was observed at the air gap of 3.5 cm with 1.7% and 4.0% relative to the skin dose results without the RS and to the largest evaluated air gap of 51.1 cm, respectively. The SOBP comparison of the beam modalities at the measuring plane at the isocenter revealed higher skin doses without RS (including RS) by up to +1.9% (+1.5%) for DS and +1.3% (+1.1%) for US compared to PBS. For all three techniques an approx. 2% rise in skin dose was observed for the largest evaluated air gap of 37.7 cm to an air gap of 6.2 cm when using an RS51. Conclusion: The study investigated aspects of skin dose of a water equivalent phantom by varying key parameters of a proton treatment plan. Parameters like the RS, the air gap, and the delivery modality have an impact on the order of 4.0% for the skin dose at the depth of 70 μm. The increases in skin dose are the effects of the contribution of the increased electron fluence at small air gaps and the emitted hadronic particles produced by the RS. [ABSTRACT FROM AUTHOR]

• Four interventional X-ray systems were tested with up to 8 skin dose mapping products. • SDM software can make considerable error in specific conditions. • No SDM product provided estimates within 40% for all set-ups and systems. • Few SDM products provided estimates within 40% for all set-ups on a specific system. • Establishing a common QC protocol for testing SDM products is currently unachievable. Online and offline software products can estimate the maximum skin dose (MSD) delivered to the patient during interventional cardiology procedures. The capabilities and accuracy of several skin dose mapping (SDM) software products were assessed on X-ray systems from the main manufacturers following a common protocol. Skin dose was measured on four X-ray systems following a protocol composed of nine fundamental irradiation set-ups and three set-ups simulating short, clinical procedures. Dosimeters/multimeters with semiconductor-based detectors, radiochromic films and thermoluminescent dosimeters were used. Results were compared with up to eight of 10 SDM products, depending on their compatibility. The MSD estimates generally agreed with the measurements within ± 40% for fundamental irradiation set-ups and simulated procedures. Only three SDM products provided estimates within ± 40% for all tested configurations on at least one compatible X-ray system. No SDM product provided estimates within ± 40% for all combinations of configurations and compatible systems. The accuracy of the MSD estimate for lateral irradiations was variable and could be poor (up to 66% underestimation). Most SDM products produced maps which qualitatively represented the dimensions, the shape and the relative position of the MSD region. Some products, however, missed the MSD region when situated at the intersection of multiple fields, which is of radiation protection concern. It is very challenging to establish a common protocol for quality control (QC) and acceptance testing because not all information necessary for accurate MSD calculation is available or standardised in the radiation dose structured reports (RDSRs). [ABSTRACT FROM AUTHOR]

• Prone position delivers relatively a lower skin dose than supine treatment technique. • Prone position can lead to lower dose in lumpectomy close to skin. • Skin dose needs to be evaluated in breast patients. • Lower dose to Organs at Risk in prone position compared to the supine position. • Skin dose in breast cancer radiation treatment is critical for the outcomes and cosmesis. To determine how the skin dose varies in patients receiving radiation treatment for breast cancer in the prone and supine positions. Fifty patients were scanned in the prone and supine positions. A radiation treatment plan was created for the left breast using a 6-MV beam for a prescribed dose of 42.66 Gy in 16 fractions. The dose was calculated using 1- and 2.5-mm calculation grid sizes and the surface dose was compared in both techniques. The median gantry angles relative to the skin surface at the central axis were 8 and 52 degrees for treatment in the prone and supine positions, respectively. The mean dose difference between the prone and supine techniques was statistically significant from 3- to 5-mm depth for both grid sizes. For the 1-mm calculation grid size, the doses at 3-, 4-, and 5-mm depths in the prone and supine techniques were 87.80% and 89.10% (P < 0.003), 91.92% and 94.50% (P < 0.00), and 95.30% and 98.20% (P < 0.00), respectively; for the 2.5-mm grid size, the respective doses were 87.10% and 88.59% (P < 0.00), 91.60% and 94.63% (P < 0.00), and 95.10% and 97.80% (P < 0.00), respectively. This study demonstrates that the prone technique facilitates a relatively lower skin dose than the supine technique. This observation is probably due to the beam angle. The beam is more perpendicular to the skin surface in the prone technique, whereas it is more tangential in the supine technique, which may deliver a higher skin dose. Thus, the dose to the skin should be evaluated in the prone technique, and if desired, the skin dose could be carefully augmented via a bolus or beam spoiler. [ABSTRACT FROM AUTHOR]