Feasibility of using micro silica bead TLDs for in-Vivo dosimetry of CT-based HDR prostate brachytherapy: An experimental and simulation study.

PURPOSE: Feasibility of silica-based dosimeters for IVD of HDR prostate brachytherapy. MATERIAL AND METHODS: 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. RESULTS: 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. CONCLUSION: Micro-silica bead dosimeters can perform offline in situ quality assurance in HDR prostate brachytherapy.

Dosimetry of small photon fields in the presence of bone heterogeneity using MAGIC polymer gel, Gafchromic film, and Monte Carlo simulation.

Background: The presence of heterogeneity within the radiation field increases the challenges of small field dosimetry. In this study, the performance of MAGIC polymer gel was evaluated in the dosimetry of small fields beyond bone heterogeneity. Materials and methods: Circular field sizes of 5, 10, 20 and 30 mm were used and Polytetrafluoroethylene with density of 2.2 g/cm3 was used as the bone equivalent material. The PDD curves, beam profiles, and penumbra widths were measured using MAGIC polymer gel, EBT2 film, and Monte Carlo simulation. Results: The maximum differences between MAGIC and EBT2 are 6.1, 4.7, 2.4, and 2.2 for PDD curves at 5, 10, 20, and 30 mm circular fields, respectively. The dose differences and distance to agreement between MAGIC and MC were within 1.89%/0.46 mm, 1.66%/0.43 mm, 1.28%/0.77 mm, and 1.31%/0.81 mm for beam profile values behind bone heterogeneity at 5, 10, 20, and 30 mm field sizes, respectively. Conclusion: The results presented that the MAGIC polymer gel dosimeter is a proper instrument for dosimetry beyond high density heterogeneity.

3D in vivo dosimetry of HDR gynecological brachytherapy using micro silica bead TLDs.

PURPOSE: This study aimed to evaluate the feasibility of defining an in vivo dosimetry (IVD) protocol as a patient-specific quality assurance (PSQA) using the bead thermoluminescent dosimeters (TLDs) for point and 3D IVD during brachytherapy (BT) of gynecological (GYN) cancer using 60 Co high-dose-rate (HDR) source. METHODS: The 3D in vivo absorbed dose verification within the rectum and bladder as organs-at-risk was performed by bead TLDs for 30 GYN cancer patients. For rectal wall dosimetry, 80 TLDs were placed in axial arrangements around a rectal tube covered with a layer of gel. Ten beads were placed inside the Foley catheter to get the bladder-absorbed dose. Beads TLDs were localized and defined as control points in the treatment planning system (TPS) using CT images of the patients. Patients were planned and treated using the routine BT protocol. The experimentally obtained absorbed dose map of the rectal wall and the point dose of the bladder were compared to the TPSs predicted absorbed dose at these control points. RESULTS: Relative difference between TPS and TLDs results were -8.3% ± 19.5% and -7.2% ± 14.6% (1SD) for rectum- and bladder-absorbed dose, respectively. Gamma analysis was used to compare the calculated with the measured absorbed dose maps. Mean gamma passing rates of 84.1%, 90.8%, and 92.5% using the criteria of 3%/2 mm, 3%/3 mm, and 4%/2 mm were obtained, respectively. Eventually, a "considering level" of at least 85% as pass rate with 4%/2-mm criteria was recommended. CONCLUSIONS: A 3D IVD protocol employing bead TLDs was presented to measure absorbed doses delivered to the rectum and bladder during GYN HDR-BT as a reliable PSQA method. 3D rectal absorbed dose measurements were performed. Differences between experimentally measured and planned absorbed dose maps were presented in the form of a gamma index, which may be used as a warning for corrective action.

Radiosensitization of Glioma Cells by Temozolomide (TMZ): A Colony Formation Assay.

BACKGROUND: Glioblastoma is one of the most radioresistant cancers. It is suggested that combination of radiotherapy with other cancer treatment modalities may increase control of tumor. Temozolomide (TMZ) is one of the most known drugs for glioblastoma. It has shown that TMZ via induction of mutation and cell death can kill glioma cells. OBJECTIVE: In the current study, we aimed to show possible radiosensitization effect of TMZ for glioma cells. In addition, results compared to response of normal fibroblast cells to TMZ and irradiation. MATERIAL AND METHODS: This is in vitro study for evaluation of the effect of TMZ and irradiation on high grade glioma cells and normal fibroblasts. The human fibroblast and glioma cells were cultured as monolayer. The cells were treated with 2000 µM TMZ, which was equal drug dose for IC50%. In addition, irradiation was done with 5Gy gamma rays. The formation of colony was observed following irradiation, treatment with TMZ, and combination both of them. RESULTS: The formation of colony for both glioma and fibroblast cells showed a reduction following irradiation or treatment with TMZ. Irradiation showed more toxicity compared to TMZ for glioma cells, but not fibroblast cells. Combination of TMZ and irradiation showed a significant reduction in the colony formation compared to irradiation or TMZ treatment alone. CONCLUSION: This study showed that TMZ increases sensitivity of both glioma and fibroblast cells to ionizing radiation.

Development of a novel and low-cost anthropomorphic pelvis phantom for 3D dosimetry in radiotherapy.

PURPOSE: The aim of this study was to construct a low-cost, anthropomorphic, and 3D-printed pelvis phantom and evaluate the feasibility of its use to perform 3D dosimetry with commercially available bead thermoluminescent dosimeters (TLDs). MATERIAL AND METHODS: A novel anthropomorphic female phantom was developed with all relevant pelvic organs to position the bead TLDs. Organs were 3D-printed using acrylonitrile butadiene styrene. Phantom components were confirmed to have mass density and computed tomography (CT) numbers similar to relevant tissues. To find out clinically required spatial resolution of beads to cause no perturbation effect, TLDs were positioned with 2.5, 5, and 7.5 mm spacing on the surface of syringe. After taking a CT scan and creating a 4-field conformal radiotherapy plan, 3 dose planes were extracted from the treatment planning system (TPS) at different depths. By using a 2D-gamma analysis, the TPS reports were compared with and without the presence of beads. Moreover, the bead TLDs were placed on the organs' surfaces of the pelvis phantom and exposed to high-dose-rate (HDR) 60Co source. TLDs' readouts were compared with the TPS calculated doses, and dose surface histograms (DSHs) of organs were plotted. RESULTS: 3D-printed phantom organs agreed well with body tissues regarding both their design and radiation properties. Furthermore, the 2D-gamma analysis on the syringe showed more than 99% points passed 3%- and 3-mm criteria at different depths. By calculating the integral dose of DSHs, the percentage differences were -1.5%, 2%, 5%, and 10% for uterus, rectum, bladder, and sigmoid, respectively. Also, combined standard uncertainty was estimated as 3.5% (k = 1). CONCLUSIONS: A customized pelvis phantom was successfully built and assessed to confirm properties similar to body tissues. Additionally, no significant perturbation effect with different bead resolutions was presented by the external TPS, with 0.1 mm dose grid resolution.

Prevalence of cancers diagnosed in Jamhuriyat Hospital, Kabul, Afghanistan.

BACKGROUNDS: Throughout the world, there exists a clear need for the maintenance of cancer statistics, forming an essential part of any rational programme of cancer control, health-care planning, etiological research, primary and secondary prevention, benefiting both individuals and society. The present work reports only on the prevalence of cancers in the Oncology Department of Jamhuriyat Hospital, Kabul, Afghanistan following several decades of war. MATERIALS AND METHODS: A quantitative retrospective cross-sectional study was conducted using the medical records of patients diagnosed and treated from October 2015 to December 2017. Data includes information on gender, age, economic status, address and types of cancer diagnosed. The data was transferred to a customized form and analysed using Microsoft Excel program to classify cancer types. RESULTS: The total number of patients with completed documents were 1025. Of these, 403 (39.3%) were male and 622 (60.7%) female. Most of the patients were in the age range of 20-70 years old. The most common cancers in women were breast cancer (45.8%), followed by oesophagus (12.5%), colorectal (4.8%), Non-Hodgkin Lymphoma (4.7%), sarcoma (4.7%), ovary (3.8%), both stomach and liver (2.6%) and cervix uteri (1.9%). Contrarily to men, esophageal cancer was highest (21.8%), followed by stomach (12.2%), Non-Hodgkin Lymphoma (9.4%), sarcoma (8.9%), gastroesophageal junction (8.9%), colorectal (8.6%), Hodgkin lymphoma (4.7%), testis (4.2%), liver (3.2%), lung (2.7%) and Nonmelanoma skin squamous cell carcinoma 9 (2.2%). CONCLUSION: Results showed that the most frequent cancers among Afghans were breast and oesophagus. The most common cancer in men was oesophagus and stomach at the age range of 50-70 years while in women, breast and oesophagus cancers were common and within the age range of 25-65 years old.

High-dose-rate brachytherapy in treatment of non-melanoma skin cancer of head and neck region: preliminary results of a prospective single institution study.

PURPOSE: Skin cancers are the most common human malignancy with increasing incidence. Currently, surgery is standard of care treatment for non-melanoma skin cancers. However, brachytherapy is a growing modality in the management of skin cancers. Therefore, we aimed to assess the outcome of patients with non-melanoma skin cancers treated by high-dose-rate (HDR) brachytherapy with surface mold technique. MATERIAL AND METHODS: In this prospective study, we recruited patients with basal cell carcinoma (BCC) and squamous cell carcinoma (SCC) of the skin who were candidates for definitive or adjuvant brachytherapy during 2013-2014. Alginate was used for making the individualized surface molds for each patient. Patients were treated with afterloading radionuclide HDR brachytherapy machine, with a total dose of 30-52 Gy in 10-13 fractions. Participants were followed for 2 years for radiation toxicity, cosmetic results, and local failures. RESULTS: A total of 60 patients (66.7% male; median age, 71 years) were included, of which 42 (70.0%) underwent definitive radiotherapy. Seventy-five percent of lesions were BCC. The mean total dose was 39.6 ± 5.4 Gy. Of patients in definitive group, 40/42 (95.2%) experienced complete clinical response after 3 months. The recurrence rate was 2/18 (11.11%) and 1/42 (2.38%) in adjuvant and definitive groups, respectively. The percentage of grade 3-4 acute (3-month post-treatment) and late toxicities (2 years post-treatment) was 6.7% and 0%, respectively. The cosmetic results were good/excellent in 96.2% of patients after 2 years of follow-up. CONCLUSIONS: With appropriate patient selection and choosing as lowest dose per fraction as possible, HDR brachytherapy with customized surface molds yields good oncological and cosmetic results for the treatment of localized skin BCC and SCC.

Adjuvant high-dose-rate brachytherapy in the management of oral cavity cancers: 5 years of experience in Iran.

PURPOSE: Brachytherapy is a cost-effective method for the management of oral cavity cancers in low to middle income countries. We aimed to evaluate the clinical outcomes of high-dose-rate interstitial brachytherapy (HDR-IBT) in patients with oral cavity cancer. MATERIAL AND METHODS: From 2009 to 2013, 78 patients (49 combined external beam radiotherapy [EBRT] plus IBT and 29 IBT monotherapy) with oral cavity cancers had been treated in our center. Slightly more than half the patients were male, and the median age was 54 years. The treatment was planned based on the Paris system. The main outcomes were disease-free and overall survival. RESULTS: The median follow-up duration was 36.5 months (range, 1.17-54.23). The actuarial four-year overall and disease-free survival rates were 83% and 65%, respectively. The local and locoregional control was achieved among 89.74% and 87.17% of patients, respectively. None of the factors including tumor size, node status, gender, and radiation modality (IBT alone vs. IBT + EBRT) had a significant statistical correlation to the local control rate. All the patients tolerated the planned treatment in the IBT alone group. Late complications included a case of trismus and three cases of catheter insertion site fibrosis. CONCLUSIONS: HDR-IBT as a monotherapy or in combination with EBRT is an appropriate option for the management of oral cavity squamous cell carcinomas, and supports the improvement in treatment outcomes and toxicity profiles in adjuvant settings.