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Iridium-192 brachytherapy dose enhancement by gold nanoparticles was investigated in five different tumor tissues to observe the tissue-related differences as an effective environmental factor in the applications of nanoparticles as radio-enhancer agents. The brachytherapy high-dose-rate source of BEBIG Ir-192, a tumor volume with five different tissues including water, Plexiglas, soft tissue, adipose, and bone with and without a uniform distribution of gold nanoparticles were mimicked by MCNPX Monte Carlo simulation code using lattice feature. Dose enhancement factors in the tumor volume were measured separately regarding the types of tissue, and a previous study using GEometry ANd Tracking 4 simulation was used for result validation. The results demonstrated that various types of tissue, as the host of gold nanoparticles, lead to different dose enhancement level, so that the bone and adipose have the lowest and the highest amount of dose enhancement factor with values 20.8% and 39.75%, respectively. The maximum difference of 4.8% was achieved from data benchmarking. The results of this study indicate that the MCNPX code can be used as a valid tool for dose measurement in the presence of nanoparticles. Moreover, tissue types of tumor as an environmental feature, alongside with the nanoparticle's size and concentration as well as the conditions of radiotherapy, should be considered in the dose calculation. [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]

Purpose To demonstrate the utility of “3D Slicer” for easy treatment verification by comparing dose-volume histograms (DVHs) calculated on pretreatment and posttreatment images. Methods and materials Thirty cervical cancer patients were CT scanned twice: first for treatment planning and a second time after the dose delivery. The initial plan was manually duplicated on the posttreatment image set in Flexiplan treatment planning system, and DVH parameters were calculated. Pretreatment and posttreatment images, organ structures, and plan data were exported from the treatment planning system to 3D Slicer to validate DVH parameter calculation with 3D Slicer. The gamma analysis was used to compare Flexiplan and 3D Slicer DVHs. Posttreatment images were rigidly fused on the initial CT to automatically transfer the data of the pretreatment plan onto the posttreatment images. DVH parameters were calculated in 3D Slicer for both image sets, and their relative variations were compared. Results In calculating DVH parameter variations, no significant differences were observed between Flexiplan and 3D Slicer. Where the registration accuracy was better than 0.03, they returned similar results for D 2 cm 3 of bladder, rectum, and sigmoid. Mean and standard deviation of DVH parameters were calculated on pretreatment and posttreatment images for several organs; both the manually duplicated plan and the automatically registered plan in SlicerRT returned comparable relative variations of these parameters. For 88% of the organs, more than 95% of the DVH dose bins passed the gamma analysis. Conclusions We tested an automated DVH assessment method with an imaging freeware, 3D Slicer, for use in image-guided adaptive brachytherapy. SlicerRT is a viable verification tool to report and detect DVH variations between different contoured images series. [ABSTRACT FROM AUTHOR]

To investigate the 106Ru dose distribution in an intraocular pseudotumor by micro silica glass beads thermo-luminescence dosimeters (TLD). Dosimetry was conducted using Monte Carlo (MC) simulation as well as an experimental setup by employing an in-house eye equivalent phantom. A BEBIG CCA model of 106Ru plaque was used. Bead TLDs were modeled using MCNPX code, choosing water and plexiglass as phantom mediums along with CCA plaque. The deposited energy and electron energy spectra were calculated using *f8 and f4 tallies, respectively. A dedicated eye-equivalent phantom was designed and fabricated by 3D-printing techniques to place glass beads. Absorbed dose at the central axis of the CCA plaque by beads TLDs was compared to manufacturer-reported data and simulation results. Maximum, minimum, and mean relative differences of 23%, 7%, and 15% with the manufacturer and 14%, 0%, and 1.6% with the simulation were obtained, respectively. Replacing glass bead material with water resulted in an average relative difference of 33.9% in absorbed energy per mass unit, corresponding to 21% and 44.8% at the first (0.5 mm depth) and last dosimetry points (9.5 mm depth), respectively. It has also been shown that glass beads can shadow each other, leading to a dose reduction of 15%. A specific eye equivalent phantom with a pseudotumor was constructed, and silica glass beads were used for dosimetry. The results of the experiment and the MC simulation are in good accord. In the case of 106Ru ophthalmic brachytherapy plaque dosimetry, replacing glass beads material with water led to a mean difference of about 34% as well as shadowing effects. This emphasizes how crucial it is to employ a reliable correction factor in clinical applications. • Creating an eye equivalent phantom capable of introducing different materials as tumour foundation. • Using TLD glass beads as a dosimeter in ocular plaque dosimetry. • Monte Carlo analysis of glass beads' material as a dosimeter. • Glass beads vs. water show 33.95% dose difference in CCA plaque dosimetry, highlighting correction factor importance. [ABSTRACT FROM AUTHOR]

Rhabdomyosarcoma (RMS) is the most common pediatric soft-tissue sarcoma, mostly involving the genitourinary (GU) tract, head and neck, and extremities. This study reports the long-term outcome of two infants with recurrent GU-RMS who underwent combination therapy with chemotherapy (ChT) and salvage brachytherapy (BT). An 18-month-old girl with vaginal bleeding and a 7-month-old boy with urinary retention presented with a diagnosis of vaginal, and bladder/prostate embryonal RMS, respectively. Surgical resection and ChT were done for both patients. However, both developed local recurrences after one year and subsequently, underwent second-line ChT and salvage interstitial high dose rate BT. The clinical target volumes for the first and second patients were treated to a totaldose of 32 Gy in 10 fractions and 35 Gy in 10 fractions, respectively, with two fractions delivered per day with a 6-h interval between fractions. After 9 years of follow-up, both patients are alive with natural growth and no late complication or evidence of recurrence. Our report shows that BT (for patients with no prior history of irradiation) could result in long-term disease-free survival in well-selected pediatric patients with recurrent GU embryonal RMS without inflicting expected adverse effects of external beam radiotherapy. [ABSTRACT FROM AUTHOR]

Feasibility of silica-based dosimeters for IVD of HDR prostate brachytherapy. Plastic dosimeter holders and a water-fillable prostate phantom were built in-house. Interstitial prostate brachytherapy and Monte Carlo simulations were performed. The treatment planning, Monte-Carlo simulation, and dosimetry results were compared. The relative differences between TLD-TPS, TLD-MCNP, and TPS-MCNP were 0.2–6.9 %, 0.5–6.5 %, and 0.6–6.3 %, respectively. Micro-silica bead dosimeters can perform offline in situ quality assurance in HDR prostate brachytherapy. • Micro-silica bead dosimeters can be used for HDR prostate brachytherapy dosimetry. • Micro-silica bead dosimeters are reliable for IVD in radiotherapy. • Micro-silica bead dosimeters can be used in high gradient dose distribution. [ABSTRACT FROM AUTHOR]

Ruthenium-106 (106Ru) plaques are specific applicators dedicated for intraocular brachytherapy. Small tumor volume and presence of vital organs in its close vicinity as well as appearance of very high dose gradient regions around the employed plaques cause unique challenges in plaque-based brachytherapy. Therefore, access to 3D dose distribution for each brachytherapy plaque is quite helpful to decide about tumor volume coverage and overexposure of surrounding sensitive organs. Current study aims to measure the 3D dose distribution for two commercially available 106Ru plaques using film dosimetry. COB (a notched-shape plaque) and CGD (a fully circular plaque) 106Ru plaques were used and dose distributions in different planes were measured by simultaneously employing a 3D printed eyeball phantom and Gafchromic EBT3 films. Finally, 3D dose distributions were acquired by interpolating the measured 2D dose data at different planes. The results showed that employing the COB plaque tilts the isodose curves toward the non-notched edge of the plaque, while no isodose tilting was observed for CGD plaque. The obtained 3D dose distributions were different for studied plaques. Non-uniform 3D dose distributions were found for both plaques which can be attributed to the plaque design and reference point position on plaque central axis. Finally, it can be concluded that the obtained 3D dose distributions can specify the optimal tumor shape which can be adequately covered by brachytherapy plaque with minimizing the dose non-uniformity and hot point formation inside the treated volume. Obtained 3D dose distribution for each plaque can be employed for patient treatment planning. • Film dosimetry of two commercially available 106Ru intraocular brachytherapy plaques. • COB (notched shape) and CGD (fully circular shape) plaques were considered. • 3D dose distribution data was measured for each plaque inside an eyeball phantom. • Non-uniform dose distribution were observed for both plaques understudy. • Followed approach can be used for plaque-based brachytherapy quality assurance. [ABSTRACT FROM AUTHOR]

This study investigated the correlation between the prescription dose and dose to the Manchester and International Commission on Radiation Units and Measurements-report 38 (ICRU-38) lymphatic trapezoid points during high-dose-rate (HDR) brachytherapy of locally advanced cervical cancer with (Cobalt-60) 60Co. A retrospective study was designed for; patients with locally advanced cervical cancer, treated by external beam radiotherapy and concurrent weekly Cisplatin-based chemotherapy, had no extended parametrial invasion and was treated by tandem-ovoid set, from 2017 to 2020. Groupe Européen de Curiethérapie-European Society for Radiotherapy and Oncology (GEC-ESTRO) based target's volume, ICRU-89 revised version of Manchester points A and B, and ICRU-38 lymph node surrogate points were determined, and their dose was recorded. Paired sample t -test, linear regression analysis, and Pearson correlation analyses were done considering a statistical significance level of 0.05 and using IBM SPSS statistics (Version 23, IBM Crop.). Seventy-four brachytherapy cases were included. A positive and strong correlation was observed between D 90 of clinical target volume (CTV HR) and points A and B dose for CTV HR 〈 15 cc and 〉 35 cc. Strong and significant (p < 0.05) correlations were achieved between pelvic wall points dose and D 90 and D 100 of the obturator and between D 50 and hot points of internal iliac lymph nodes. A strong correlation was obtained between D 50 and D 90 of external iliac lymph nodes and their ICRU points. Strong correlations were obtained between dose to the pelvic lymphatic chains and their historical ICRU-38 surrogate points during HDR brachytherapy of locally advanced cervical cancer patients with 60Co tandem-ovoid applicator sets. The correlation strength between point A and prescription dose highly depends on the CTV HR volume. [ABSTRACT FROM AUTHOR]

In vivo dosimetry (IVD) is a powerful method for treatment dose verification which has been applied in brachytherapy (BT) using different dosimetry systems and technologies. However, implementation of IVD in routine clinical workflow and patient quality control is limited in many departments. This is due to challenges related to the high gradient dose distribution, large dose range and dose rate around BT sources. The apparent lack of utilization of high accuracy IVD systems, which are straightforward to use in a clinic, is currently a significant missed opportunity for quality and safety assurance. Commercial silica bead thermoluminescent dosimeters (TLDs) (Jafari et al., 2014a, 2014b) appear suitable for IVD in high dose rate (HDR) BT. The dose response of silica bead TLDs was characterized in a water phantom and a constructed anthropomorphic pelvis phantom by exposing them with 60Co source as the used source in our BT department. Also dose response of bead TLDs was defined in a CTDI phantom with 120 kV energy exposure. It was found that measured dose differences to planning system calculations varied from −2.0% to 2.9% during pelvis phantom investigations. Mean experimental dose differences did not exceed the standard uncertainty 7.0% (k = 2) estimated for this study. The phantom results presented indicate that silica beads TLDs may be used to provide in vivo verification of delivered dose in intracavitary HDR BT although this work verifies use only for 60Co source. • Dosimetric response of bead TLDs was evaluated for 60Co HDR brachytherapy source(s). • Dose differences of bead TLDs to TPS varied from −2.0% to 2.9% in phantom dosimetry. • Dosimetric response of bead TLDs was evaluated in a CTDI phantom by exposing to 120 kV. [ABSTRACT FROM AUTHOR]