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Cancer incidence has been increasing over the years and it is the second leading cause of death globally [1]. The therapeutic strategies in killing the cancerous tissue while keeping the normal healthy tissue uninterrupted can be further improved by introducing nanoparticles (NPs) as radiosensitizers in radiotherapy. In pre-clinical research, a few nanoparticle elements had shown the potential to be radiosensitizers, such as gold, superparamagnetic iron oxide, platinum, and bismuth nanoparticles. Bismuth oxide nanoparticles (BiONPs) have been investigated as a potential radiosensitizer in radiotherapy due to their least toxic and biocompatibility properties. In addition, due to the presence of metallic nanoparticles in cells and their environment, more DNA damage will be introduced and thus enhance the radiation treatment efficacy. This research project was conducted to evaluate the potential of BiONPs to increase the radiation treatment in MCF-7 breast cancer cells and their side effects on the non-targeted breast cancer cells. BiONPs were synthesized through the hydrothermal method, as established in the previous study [2]. The treated and control cells in flasks were irradiated with radiation doses between 0 to 12 Gy at a constant dose rate of 300 cGy/minutes in the beam field size of 10 cm x 10 cm for a 6 MV photon beam, delivered with linear accelerator Primus model (Siemen Healthcare, USA). The irradiated cell-conditioned medium (ICCM) was collected from the targeted cells and transferred into the non-targeted cells. The cell viability assay was employed to evaluate the effect of BiONPs on directly irradiated and non-irradiated cells. In our prior work, the BiONPs had shown to boost radiosensitisation effects in treated cells compared to control cells, with a sensitisation enhancement ratio (SER) of 1.38 [3], as shown in Figure 1. The increased radiosensitisation effects might be attributed to the characteristics of BiONPs with a high effective atomic number (Z=83), which promotes radiation interaction, mainly radiation absorption and scattering. Meanwhile, the present study demonstrated that the non-irradiated MCF-7 cells could maintain their cell viability for more than 80% after 48 h incubation with ICCM treated with BiONPs at 2, 6, and 12 Gy. Furthermore, a comparable trend in cell viability was observed in non-irradiated MCF-7 cells for treated and control groups (p

This study aims to measure the radial dose function and anisotropy function F(r, θ) of high Dose Rate (HDR) 192Ir source in a fabricated water-equivalent phantom using Gafchromic® EBT3 film and TLD-100H and to compare the results obtained with the MCNP5 calculated values. The phantom was fabricated using Perspex PMMA material. For, the EBT3 films with a required dimension and TLD-100H chips were placed at r=1, 2, 3, 5, and 10 cm from the source. The F(r, θ) measurements were carried out at r=1, 2, 3, 5, and 10 cm with the angle range from 10° to 170°. The result of from EBT3 film and TLD-100H was in good agreement (2.10%±1.99). Compared to MCNP5, the differences are within 0.31% to 11.47% for EBT3 film and 0.08% to 10.58% for TLD-100H. For the F(r, θ), an average deviation with the MCNP5 calculation is 4.94%±2.7. For both and F(r, θ), the effects are prominent at r=10 cm. At this distance, the response of both Gafchromic® EBT3 film and TLD-100H shows less sensitivity as the dose followed the inverse square law. This work demonstrates that Gafchromic® EBT3 film dosimeter and TLD-100H are suitable dosimeters in 192Ir dosimetric measurements at a radial distance of ˂5 cm

Background: This dosimetric study compared lateral wedge with medial only cardiac shielding (LEMONADE) technique, for left chest wall (LCW) irradiation against three other commonly used techniques. Materials and methods: Dosimetric parameters of 22 consecutive LBC patients treated using the P1 (LEMONADE technique) were compared with 3 other virtually reconstructed plans: no cardiac shielding with paired wedges; P2 (paired wedges and medial only Y-direction shielding) and P3 (paired wedges and bilateral Y-direction shielding). Results: P1 showed better target volume (TV) coverage with the mean 90% isodose coverage of 85.59% ± 5.44 compared to 78.90% ± 8.59 and 74.22% ± 9.50 for P2 and P3, respectively. Compared to no cardiac shielding, for a 4.65% drop in TV coverage the V26Gy of heart dropped from 6.68% to a negligible 0.85% for P1. TV receiving < 30Gy is also significantly lesser for P1 compared to P2 and P3 (5.42% vs 10.64% and 15.8%), whilst there is a small difference of 2.75% between no cardiac shielding and P1. Conclusion: With the improvement in BC survival rate, cardiac toxicity associated with adjuvant irradiation for LBC is a major concern. P1 (LEMONADE) technique has a good compromise between cardiac sparing and target coverage and should suffice for most LCW irradiations. Furthermore, the LEMONADE technique is a simple, reproducible and involves fast planning for cardiac sparing, which is ideal for under-resourced departments with heavy workload.

INTRODUCTION: This retrospective study aims to evaluate the doses of organs at risk (OARs) calculated by conventional two-dimensional (2-D) and three-dimensional (3-D) treatment planning techniques in hybrid high dose rate (HDR) brachytherapy for cervical cancer. MATERIALS AND METHODS: Data of five patients treated with combination of intracavitary and interstitial brachytherapy were used. For each implant, computed tomography (CT) images were obtained, and the clinical target volume and OARs were contoured on CT images. In 3-D planning, the volumes of OARs were derived from dose-volume histogram (DVH) on a dose volume of 2 cc for bladder, rectum, and sigmoid. The OARs defined in replanning for 2-D treatment were the ICRU-38 bladder (bICRU) and rectum (rICRU) points. Paired T-tests were used to analyse the radiation doses of bladder and rectum obtained from both techniques. RESULTS: The mean point doses evaluated via bICRU) and rICRU were 89.34 GyEQD2 and 75.92 GyEQD2, respectively. Meanwhile, the mean volumetric doses of D2cc for bladder and rectum were 80.50 GyEQD2 and 69.08 GyEQD2, respectively. There is a significant difference in mean doses of ICRU point and D2cc volume for bladder (p0.05). Overall, ICRU point doses overestimated volumetric D2cc doses with a mean dose ratio of 1.110 for bladder and 1.099 for rectum respectively. CONCLUSION: The bICRU in 2-D planning could not represent the bladder 2 cc used in 3-D planning, thus resulting in different total dose; whereas rICRU of 2-D planning was discovered to be similar with rectum 2 cc of 3-D planning and deemed reliable in total dose estimation

This is a retrospective study, the organ doses to the bladder and rectum were compared between Nucletron PLATO V14.2.3 (BV) and newer version software Oncentra MasterPlan V4.3 (OMP) treatment planning systems (TPS). The treatment data of 32 intracavitary brachytherapy patients at Hospital Universiti Sains Malaysia from January 2010 to June 2015 were used. These data sets were used for catheter reconstruction for both PLATO and OMP TPS followed by independent verification using Excel. There is no significant difference in mean doses to organs at risk (OARs) that calculated by both TPS (p>0.05). The mean percentage of doses calculated by PLATO TPS for bladder and rectum were 66.58 ± 27.42 % and 46.27 ± 14.47 % respectively. While the mean percentage of doses for bladder and rectum calculated by OMP TPS were 65.68 ± 24.24 % and 46.46 ± 16.66 respectively. The mean percentage difference in doses comparison between independent verification calculation and PLATO TPS was 1.96 ± 6.00% and then became 6.37 ± 5.17% when it was compared with OMP TPS. Overall, the dose calculation differences for both versions of TPS were within the range recommended by Nuclear Regulatory Commission (NRC). The dose calculations of the two treatment planning systems showed good agreement and both could be used in planning intracavitary brachytherapy for cervical cancer. Whereas Excel based independent verification suitable to be implemented as routine dose verification programme prior to treatment delivery. DOI : http://dx.doi.org/10.17576/JSKM-2021-1901-13

The efficacy of recombinant human thyroid stimulating hormone (rhTSH) and thyroid hormone withdrawal (THW) in estimating the whole body radioactive clearance was done by measuring the exter...

Purpose The aim of this study was to investigate the potential of the synergetic triple therapeutic combination encompassing bismuth oxide nanoparticles (BiONPs), cisplatin (Cis), and high dose rate (HDR) brachytherapy with Ir-192 source in breast cancer and normal fibroblast cell line. Methods In vitro models of breast cancer cell lines (MCF-7, MDA-MB-231) and normal fibroblast cell line (NIH/3T3) were employed. Cellular localization and cytotoxicity studies were conducted prior to inspection on the radiosensitization effects and generation of reactive oxygen species (ROS) on three proposed radiosensitizers: BiONPs, Cis, and BiONPs-Cis combination (BC). The optimal, non-cytotoxic concentration of BiONPs (0.5 mM) and the 25% inhibitory concentration of Cis (1.30 µM) were applied. The radiosensitization effects were evaluated by using a 0.38 MeV Iridium-192 HDR brachytherapy source over a prescribed dose range of 0 Gy to 4 Gy. Results The cellular localization of BiONPs was visualized by light microscopy and accumulation of the BiONPs within the vicinity of the nuclear membrane was observed. Quantification of the sensitization enhancement ratio extrapolated from the survival curves indicates radiosensitization effects for MCF-7 and MDA-MB-231 when treated with BiONPs, Cis, and BC. However, NIH/3T3 cells exhibited contradictive behavior as it only reacted towards the BC combination. Nonetheless, the MCF-7 cell line loaded with BC shows the highest SER of 4.29. ROS production analysis, on the other hand, shows that Cis and BC radiosensitizers generated the highest free radicals in comparison to BiONPs alone. Conclusion A BiONPs-Cis combination was unveiled as a novel approach that offers promising radiosensitization enhancement that will increase the efficiency of tumor control while preserving the normal tissue at a reduced dose. This data is the first precedent to prove the synergetic implication of BiONPs, Cis, and HDR brachytherapy that will be beneficial for future chemoradiotherapy strategies in cancer care.

Noor Nabilah Talik Sisin,1 Khairunisak Abdul Razak,2 Safri Zainal Abidin,3 Nor Fazila Che Mat,1 Reduan Abdullah,1,4 Raizulnasuha Ab Rashid,1 Muhammad Afiq Khairil Anuar,1 Wan Nordiana Rahman1 1Medical Radiation Programme, School of Health Sciences, Universiti Sains Malaysia, Kubang Kerian, Kelantan,Malaysia; 2Material Engineering Programme, School of Materials and Mineral Resources Engineering, Universiti Sains Malaysia, Nibong Tebal, Penang, Malaysia; 3Oncological and Radiological Sciences Cluster, Advanced Medical and Dental Institute, Universiti Sains Malaysia, Bertam, Penang, Malaysia; 4Nuclear Medicine, Radiotherapy and Oncology Department, Hospital of Universiti Sains Malaysia, Kubang Kerian, Kelantan, MalaysiaCorrespondence: Wan Nordiana RahmanSchool of Health Sciences, Universiti Sains Malaysia, Kelantan, MalaysiaTel +6097677811Email wandiana@usm.myPurpose: This study aimed to quantify synergetic effects induced by bismuth oxide nanoparticles (BiONPs), cisplatin (Cis) and baicalein-rich fraction (BRF) natural-based agent on the reactive oxygen species (ROS) generation and radiosensitization effects under irradiation of clinical radiotherapy beams of photon, electron and HDR-brachytherapy. The combined therapeutic responses of each compound and clinical radiotherapy beam were evaluated on breast cancer and normal fibroblast cell line.Methods: In this study, individual BiONPs, Cis, and BRF, as well as combinations of BiONPs-Cis (BC), BiONPs-BRF (BB) and BiONPs-Cis-BRF (BCB) were treated to the cells before irradiation using HDR brachytherapy with 0.38 MeV iridium-192 source, 6 MV photon beam and 6 MeV electron beam. The individual or synergetic effects from the application of the treatment components during the radiotherapy were elucidated by quantifying the ROS generation and radiosensitization effects on MCF-7 and MDA-MB-231 breast cancer cell lines as well as NIH/3T3 normal cell line.Results: The ROS generated in the presence of Cis stimulated the most substantial amount of ROS compared to the BiONPs and BRF. Meanwhile, the combination of the components had induced the higher ROS levels for photon beam than the brachytherapy and electron beam. The highest ROS enhancement relative to the control is attributable to the presence of BC combination in MDA-MB-231 cells, in comparison to the BB and BCB combinations. The radiosensitization effects which were quantified using the sensitization enhancement ratio (SER) indicate the highest value by BC in MCF-7 cells, followed by BCB and BB treatment. The radiosensitization effects are found to be more prominent for brachytherapy in comparison to photon and electron beam.Conclusion: The BiONPs, Cis and BRF are the potential radiosensitizers that could improve the efficiency of radiotherapy to eradicate the cancer cells. The combination of these potent radiosensitizers might produce multiple effects when applied in radiotherapy. The BC combination is found to have the highest SER, followed by the BCB combination. This study is also the first to investigate the effect of BRF in combination with BiONPs (BB) and BC (BCB) treatments.Keywords: cisplatin, bismuth oxide, baicalein, radiosensitization, reactive oxygen species

Radiotherapy is an important treatment modality for cancer treatment, particularly for locally advanced tumours and it is known to induce cell death in tumours. Radiotherapy is limited by the total dose that can be prescribed without damaging normal tissueThe main aims of radiotherapy to optimally eradicate tumours while sparing the normal tissue could be achieved with the combination treatment using natural products based medicinal plants. Oroxylum indicum (OI) is a Malaysian consumable plant with a variety of health attributes that contains useful active biocompound that serves as anticancer agent. In this study, the potentials of OI extracts to increase cells radiosensitivity towards radiotherapy were investigated. Initially, the cytotoxic effects of OI extracts were determined in-vitro using HeLa cells. The cells with non-toxic concentration of OI extracts were irradiated with 6 MV and 10 MV photon beams. The cell survivals after irradiation were then evaluated using PrestoBlue assay. The OI extracts with maximum concentration of 0.01 mg/ml are found nontoxic to HeLa cells. The combination of OI extracts and irradiation are found to reduce the cells survival which indicates radiosensitization effects. The sensitization enhancement ratio (SER) calculated indicate higher radiosensization observed for 6 MV photon beams compare to 10 MV photon beams. SER also increased at higher OI concentration. In conclusion, the OI extracts are found to induce radiosensitization in HeLa cancer cells when irradiated with megavoltage photon beams. This study indicates the potential of plant based natural product to be applied as radiosensitizer to increase the therapeutic efficiency in radiation therapy of cancer.

Gold nanoparticles (AuNPs) have been experimentally proven to induce radiosensitization effects particularly for kilovoltage photon beam. Theoretically, AuNPs bombarded with kilovoltage photon beam would increase the photoelectric interactions cross section and hence increase cell death. Despite the intriguing finding, this type of beam is not common in clinical radiotherapy and possesses limited application compare to megavoltage beams. In this study, quantification of the radiosensitization effects acquired from clinical megavoltage photon, electron, and high-dose rate (HDR) gamma rays from Ir-192 source were conducted. In addition, radiobiological characterization of the cell survival curves that are commonly described by linear-quadratic (LQ) model was also evaluated using multi-target (MT) and repairable conditionally repairable (RCR) model. Significant sensitization enhancement ratios (SER) were obtained particularly for 15 MeV electron beams in which the amplification of radiation effects by AuNPs is up to the factor of 1.78. The results also demonstrate validity of experimental models to describe the cell survival curve and determine the radiosensitization effects. However, slight variation was observed for SER values computed from each model which indicate the importance to specify the quantification method. Adoption of radiobiological models and their parameters could also be employed as indicator to explain the mechanistic events in the AuNPs’ radiosensitization effects. As conclusion effective radiosensitization by megavoltage clinical radiotherapy beams could be achieved and precise radiobiological characterization drawn from radiobiological models may provide insight towards radiobiological impacts induced by AuNPs.

Background: Radiation induced bystander effects (RIBEs) occurs in unirradiated cells exhibiting indirect biological effect as a consequence of signals from other irradiated cells in the population. Objective: In this study, bystander effects in MCF-7 breast cancer cells and hFOB 1.19 normal osteoblast cells irradiated with gamma emitting HDR Brachytherapy Ir-192 source were investigated.Material and Methods: In this in-vitro study, bystander effect stimulation was conducted using medium transfer technique of irradiated cells to the non-irradiated bystander cells. Cell viability, reactive oxygen species (ROS) generation and colony forming assay was employed to evaluate the effect. Results: Results indicate that the exposure to the medium irradiated MCF-7 induced significant bystander killing and decreased the survival fraction of bystander MCF-7 and hFOB from 1.19 to 81.70 % and 65.44 %, respectively. A significant decrease in survival fraction was observed for hFOB 1.19 bystander cells (p < 0.05). We found that the rate of hFOB 1.19 cell growth significantly decreases to 85.5% when added with media from irradiated cells. The ROS levels of bystander cells for both cell lines were observed to have an increase even after 4 h of treatment. Our results suggest the presence of bystander effects in unirradiated cells exposed to the irradiated medium. Conclusion: These data provide evidence that irradiated MCF-7 breast cancer cells can induce bystander death in unirradiated MCF-7 and hFOB 1.19 bystander cells. Increase in cell death could also be mediated by the ROS generation during the irradiation with HDR brachytherapy.

Background Nanomaterials have been applied as radiosensitizer in an effort to improve the effectiveness of radiotherapy in killing cancer cells while simultaneously sparing the healthy normal tissue. Increase in radiotoxicity to the cancerous region might also influence the non-targeted cells through radiation-induced bystander effect (RIBE) mechanism. In this study, we implemented Bi2O3 NPs as radiosensitizer in combination with megavoltage radiotherapy and probe into the RIBE consequences in the non-targeted cells. Aim To investigate the effects of bismuth oxide nanoparticles (Bi2O3 NPs) on RIBE triggered in MCF-7 and hFOB 1.19 after irradiation with 10 MV clinical photon beam. Materials and methods The MCF-7 (human breast cancer) and hFOB 1.19 (human fetal osteoblast) cell lines were incubated with and without Bi2O3 NPs prior to irradiation. The treated cells were irradiated with radiation doses of 0 to 12 Gy using 10 MV photon beam in a single exposure. The irradiated-cell conditioned medium (ICCM) were collected from the targeted cells and transferred into the non-targeted cells. Reactive oxygen species (ROS), cell viability and colony forming assay was employed to evaluate the effect. Results The present study demonstrated that the MCF-7 and hFOB 1.19 bystander cells are able to maintain their cell viability for more than 80% after 48 h incubation with ICCM treated with Bi2O3 NPs at 2 Gy radiation dose. The percentage of cell survival fraction of hFOB 1.19 cells which received ICCM with Bi2O3 NPs decreased to 86.8%, in contrast to MCF-7 bystander cells which show an increment in their cells survival after treatment with Bi2O3 NPs. Our results show that the ROS level was increased in the bystander cells, but the addition of Bi2O3 NPs did not significantly increase the ROS level. Conclusions The application of nanoparticles for radiosensitization during radiotherapy must also considered the RIBE responses in the non-irradiated cells. These findings provide evidence that the use Bi2O3 NPs as radiosensitizer in radiotherapy is safe and do not significantly increase the RIBE responses in non-targeted cells.

The study focused on the measurement of percentage depth dose (PDD) in high energy photons and electrons by using the optically stimulated luminescent (OSL) dosimeters. The beam output calibration was performed on 6 MV photons and 6 MeV electrons and compared to that in the ionization chamber. The PDD was measured in 6 MV photons and 6 MeV electrons and the PDD curves were plotted by using the OSL dosimeters. The PDD curves were compared to that in other common dosimeters including ionization chamber, Gafchromic® EBT2 film dosimeter and the treatment planning software (TPS). The results showed that the beam output calibration measured by using the OSL dosimeters was in good agreement to the ionization chamber within 1.6 and 5.9% percentage of discrepancy for both 6 MV photons and 6 MeV electrons respectively. The measured PDD by using the OSL dosimeters were also in in good agreement to the ionization chamber, EBT2 film and TPS software within percentage 13.4 and 10.4% of discrepancies for 6 MV photons and 6 MeV electrons respectively. The overall results indicated the suitability of OSL dosimeters to be used for direct dosimetry measurements in high energy photons and electrons.

The study focused on the use of fabricated bolus materials based on the polyvinyl alcohol (PVA) to increase the surface dose on high energy photons and electrons. The PVA based bolus materials were fabricated at 2.5, 5, 7.5 and 10% PVA in water at target density of 1.0 g/cm3. The PVA based boluses were scanned by using the computed tomography (CT) scanner along with the solid water phantoms. The percentage depth (PDD) dose of the solid water phantoms and the PVA based bolus materials were measured by using the treatment planning software (TPS) at 6 and 10 MV photons and 6 and 9 MeV electrons. The PDD curved obtained were compared to that of the standard bolus material and the surface dose were measured. The results showed that the PDD curves of solid water phantoms with PVA based bolus materials were consistent with that in standard bolus material within 1.4% percentage of difference for both 6 and 10 MV photons and within 2.9 and 1.4% percentage of differences in 6 and 9 MeV electrons respectively. The increment of surface dose in PVA based bolus materials were in excellent agreement to the standard bolus material and the percentage of PVA did not significantly affect the surface dose. The overall results showed the potential use of the PVA to be used as bolus material for clinical photons and electrons.

It has become a great challenge in the modern radiation treatment to ensure the accuracy of treatment delivery in electron beam therapy. Tissue inhomogeneity has become one of the factors for accurate dose calculation, and this requires complex algorithm calculation like Monte Carlo (MC). On the other hand, computed tomography (CT) images used in treatment planning system need to be trustful as they are the input in radiotherapy treatment. However, with the presence of metal amalgam in treatment volume, the CT images input showed prominent streak artefact, thus, contributed sources of error. Hence, metal amalgam phantom often creates streak artifacts, which cause an error in the dose calculation. Thus, a streak artifact reduction technique was applied to correct the images, and as a result, better images were observed in terms of structure delineation and density assigning. Furthermore, the amalgam density data were corrected to provide amalgam voxel with accurate density value. As for the errors of dose uncertainties due to metal amalgam, they were reduced from 46% to as low as 2% at d80 (depth of the 80% dose beyond Zmax) using the presented strategies. Considering the number of vital and radiosensitive organs in the head and the neck regions, this correction strategy is suggested in reducing calculation uncertainties through MC calculation.

The study aims to investigate the effect of dose calculation algorithms on the estimate normal tissue complication probability (NTCP) of thoracic cancer. Dose distributions of treatment plans are calculated by using Collapsed Cone (CC) and Pencil Beam (PB) algorithms from Oncentra Masterplan treatment planning system. Four treatment plans of thoracic cancers are created and dose volume histograms (DVHs) from each planning were evaluated based on criteria of acceptance level. The DVH data of the treatment planning were exported to Biosuite Software to compute the NTCP values. The NTCP were calculated accounting for the CC and PB algorithm using the Lyman-Kutcher-Burman (LKB) and Relative Seriality (RS) model. The NTCP values of the LKB model are found to have slightly higher values compare to RS model for all treatment planning using both algorithms. This study also demonstrates that the dose calculation algorithms of CC and PB did not significantly influence the computed NTCP value in the present treatment planning of thoracic cancer.

Escalation of biological damage through the induction of dose enhancement effect in radiotherapy cancer treatment by high-Z nanoparticles (NPs) has recently been the subject of growing interest. Hence, this study was conducted primarily to investigate the enhancement of brachytherapy (source Ir192) efficacy by bismuth oxide nanoparticles (BiONPs) on cervical cancer cells. Radiosensitization effect was tested against different size and concentration of BiONPs. After irradiation with radiation doses ranging from 0 to 4 Gy, the survival of the cell was quantified by clonogenic assay and presented in survival curves fitted using the LQ model. Dose enhancement (DE) factor was extrapolated from the curve at 50% of cell survival and calculated. The results marked out the dependency of DE on nanoparticles size and concentrations. The optimum size of BiONPs was found to be 80 nm with a concentration of 0.00025 mM, in which the DEF is 1.88. In conclusion, this study suggests that the induction of the DE effect is dependent on the size and concentration of the nanoparticles.

The aim of this study is to study the effects of non –homogenous region closer to the HDR Brachytherapy source. Radial widths of 1, 3 and 5 cm of an inhomogeneous cylindrical area filled with bone and lung tissue in a water phantom are modelled in this study. The effects of this inhomogeneity to the g(r) and F(r,θ) of Nucletron 192Ir microSelectron HDR source are assessed. The results show that the assumption of homogeneous water leads to underestimation of the bone dose by the treatment planning system. Meanwhile, overestimation of the dose is observed in the surrounding area. A relative difference of up to 19% is calculated for the largest bone volume. Contrast results are observed for the lung inhomogeneity model. A relative difference of up to 12% is observed in the lung dose. The presence of inhomogeneous region in the water phantom affects the anisotropy function; at a radial distance greater than 5 cm. Our results indicate that the presence of bone and lung inside the water phantom affect the g(r) and F(r,θ) in HDR brachytherapy. The degree of the effects depends on the material, position and volume of the inhomogeneity area.

Superparamagnetic Iron Oxide Nanoparticles (SPIONs) has been the focus in medical imaging as MRI contrast agents. SPIONs demonstrate intriguing properties that not only advantageous in diagnostic imaging but also for therapeutic application. In this study, the radiosensitization characteristic of SPIONs in electron beam radiotherapy and brachytherapy were investigated. This study was conducted in-vitro using HeLa cells with SPIONs (15 nm) concentration of 1, 2 and 3 mMol/L. Irradiations were done at doses ranging from 0 to 10 Gy using electron beams of energy 6 and 12 MeV as well as 0.38 MeV 192Ir brachytherapy source. Cell survivals were determined from clonogenic assay. Radiosensitization characterization was performed by analyzing the sensitization enhancement ratio (SER) expolated from the survival curves. The results show SPIONs induce radiosensitization effects in electron beams especially at lower energy with SER value obtained up to 1.5. The radiosensitization is more prominent for brachytherapy with SER value around 2. Concentrations of SPIONs also play important roles in which higher SPIONs concentration are more likely to increase radiosensitization effects. In conclusion, radiosensitization are dependent on radiation energy and concentration of the SPIONs. Further characterization of the radiosensitization induced by SPIONs may enable clinical translation of SPIONs as radiosensitizer in radiotherapy.

This paper aims to assess the dose-response characteristics of delaminated GAFCHROMIC™ EBT3 films for radiotherapy beams. Delaminated EBT3 films were produced by peeling off the top polyester substrate of original EBT3 using surgical precision forceps. The films were irradiated to 500 cGy with photon beams of 6 MV and 10 MV, while proton and 192Ir exposures were conducted at nominal energies of 150 MeV and 0.38 MeV respectively. Digitisations were made using a flatbed scanner in Red-channel for optimum sensitivity. Analyses of data fitting, reading reproducibility, film integrity and energy dependency were then implemented for comparison with original EBT3 films. Results of R2 in each curve suggested that the selected non-linear function appropriately fits the data with low reduced chi-square. However, the delaminated films experience integrity degradation of up to 13% due to active layer distress, affecting the reading reproducibility with values extending to 1.0%. Plus, the mean relative response ratio of energy dependency for delaminated EBT3 in photon irradiations was observed at 0.97, which is inferior to their original counterpart. In summary, the delaminated EBT3 yields comparable dose-response behaviour despite integrity deterioration. It is important to factor film delamination uncertainties into existing uncertainty budget as it is instrumental in reading dose-response deviations. Accurate evaluation together with reliable fabrication processes could make delaminated EBT3 attractive in specific applications including α-particles dosimetry and ultraviolet radiation monitoring.

The dose measurement using Al2O3 OSL dosimeter (OSLD) was carried out at low and high energy x-ray. The dose at low energy x-ray was measured at 40, 71 and 125 kVp x-ray energies. The dose ar high energy x-ray was measured at 6 and 10 MV x-ray energies measured at the depth of maximum dose (Zmax). The results were compared to that in ionization chamber and LiF: Mg,Ti thermoluminescent dosimeters (TLD100). The results showed that the dose of OSLD were less in agreement to ionization chamber compared to that in TLD100. The dose of OSLD however was in good agreement to that in ionization chamber at high energy x-ray. The dose measured using OSLD were found to be more consistence at high energy x-ray shown by the standard deviation of the readings. The measurement of x2 showed that the readings of OSLD were close to that in ionization chamber with values of 2.21 and 4.63 for 6 and 10 MV respectively. The results indicated that OSLD is more suitable for dose measurement at high energy x-ray.

The effective atomic number of tannin-added Rhizophora spp. particleboards was determined based on elemental composition using Energy Dispersive X-ray Analysis (EDXA). The value of mass attenuation coefficients were measured using 137Cs and 60Co gamma energies. The attenuation properties of PDD curves and beam profile of tannin-added Rhizophora spp. particleboards were investigated using Gafchromic EBT2 film at 6 MV photon and 6 MeV electrons and compared to the value in water and solid water phantoms. The results showed that tannin-added Rhizophora spp. particleboards having effective atomic number close to the value of water. The mass attenuation coefficients were near to the value of water with χ2 values of 0.018 and 0.357 to 137Cs and 60Co gamma energies respectively. The PDD of tannin-added Rhizophora spp. particleboards at 6 MV photons showed good agreement within 3.21 and 5.91% to that in solid water phantoms and water respectively. The PDD at 6 MeV electrons showed a good agreement within 3.32 and...

The study is carried out to assess the exposure rate that could contribute to public exposure in a radioiodine ward delay tank facility of Radiotherapy, Oncology and Nuclear Medicine, Department, Hospital Universiti Sains Malaysia (HUSM). The exposure rate at several locations including the delay tank room, doorway and at the public walking route was measured using Victoreen 415P-RYR survey meter. The radioactive level of the 131I waste was measured using Captus 3000 well counting system. The results showed that exposure rate and total count of the delay tank sample increased when the radioiodine ward was fully occupied with patient and reduced when the ward was vacant. Occupancy of radioiodine ward for two consecutive weeks had dramatically increased the exposure rate around the delay tank and radioactive level of 131I waste. The highest exposure rate and radioactive level was recorded when the ward was occupied for two consecutive weeks with 177.00 µR/h and 58.36 kcpm respectively. The exposure rate dec...

A set of tannin-based Rhizophora spp. particleboard phantoms with dimension of 30 cm x 30 cm was fabricated at target density of 1.0 g/cm3. The mass attenuation coefficient of the phantom was measured using 60Co gamma source. The phantoms were scanned using Computed Tomography (CT) scanner and the percentage depth dose (PDD) of the phantom was calculated using treatment planning system (TPS) at 6 MV and 10 MV x-ray and compared to that in solid water phantoms. The result showed that the mass attenuation coefficient of tannin-based Rhizohora spp. phantoms was near to the value of water with χ2 value of 1.2. The measured PDD also showed good agreement with solid water phantom at both 6 MV and 10 MV x-ray with percentage deviation below 8% at depth beyond the maximum dose, Zmax.

Some of the commercial solid phantoms were unable to provide a good simulation to water at low and high energy ranges. A potential phantom from Malaysian mangrove wood family, Rhizophoraspp was fabricated with addition of Soy Protein. An Electron Gamma Sho (EGSnrc) code was used to evaluate the dose distribution on Rhizophoraspp Soy Protein phantom at 6 MV photon beam energy. The result of the Rhizophoraspp Soy Protein phantom was then compared with the water phantom and the solid water phantom. This study showed that the uncertainty between Rhizophoraspp Soy Protein phantom and the water phantom and the solid water phantom is less than 8 % at certain depth. These comparable results have demonstrated the potential of the Rhizophoraspp Soy Protein phantom as another option for solid phantom in dosimetry purposes. Keywords : mangrove wood; solid water phantom; water equivalent phantom; EGSnrc; depth dose.

The aim of this project is to do comparative study in calibrating Ir-192 source using well ionization chamber and air measurement using Farmer ionization chamber. To calibrate the Ir-192 using well ionization chamber, the HDR unit was programmed so that the source was at the most sensitive position inside the well-chamber. The charges were measured at 45 second time interval two times using the electrometer operated at +300V and -300V. Sources air kerma strength was determined based on the AAPM task group 43 brachytherapy dosimetry protocol. In the in-air method using the Farmer ionization chamber and calibration jig, the HDR unit was programmed so that the source was at the position that gave the maximum response in the catheter. The source air kerma strength was calculated using a formula proposed by Goestch et al, (1991). The Ir-192 source air kerma strength by the well chamber was 2.7780cGym2/h while in the in-air measurement was 2.609cGym2/h. Both results are less than 3% from the source strength written in the calibration certificate. The well chamber method is quite direct and less time consuming compare to the in-air measurement and this is the method utilised in HUSM.

This study was done to investigate the verification technique of treatment plan quality assurance for brachytherapy. It is aimed to verify the point doses in 192Ir high dose rate (HDR) brachytherapy between Oncentra Masterplan brachytherapy treatment planning system and independent calculation software at a region of rectum, bladder and prescription points for both pair ovoids and full catheter set ups. The Oncentra TPS output text files were automatically loaded into the verification programme that has been developed based on spreadsheets. The output consists of source coordinates, desired calculation point coordinates and the dwell time of a patient plan. The source strength and reference dates were entered into the programme and then dose point calculations were independently performed. The programme shows its results in a comparison of its calculated point doses with the corresponding Oncentra TPS outcome. From the total of 40 clinical cases that consisted of two fractions for 20 patients, the results that were given in term of percentage difference, it shows an agreement between TPS and independent calculation are in the range of 2%. This programme only takes a few minutes to be used is preferably recommended to be implemented as the verification technique in clinical brachytherapy dosimetry.

Treatment interruption is not uncommon in radiotherapy. Common reasons for treatment interruption include machine breakdown, holidays and patient severe radiation reactions. Here RTtxGap, an Android application to assist calculations of compensation for treatment gap, is reported. It uses linear quadratic (LQ) model to calculate the biological effective dose (BED) that is used to solve for treatment gap compensations. Solutions are calculated using BED equation, with consideration for tissue proliferation. The accuracy of results has been verified using LQL Equiv software to be accurate within 1%. Five treatment interruption examples were used to illustrate the capability of the software to calculate the treatment compensation schedules. Solving these examples also illustrates the general consensus regarding compensating for unscheduled treatment interruptions, which ultimately involves balancing the BEDs of tumour and organ at risk. In addition to compensation for treatment gap, RTtxGap can also be used to calculate equivalent total dose in 2-Gy fraction (EQD2), to modify treatment schedule and to calculate alternative dose prescriptions having the same isoeffect.