Investigation of TG-43 Dosimetric Parameters for 192Ir Brachytherapy Source Using GATE Monte Carlo Code.

Purpose: According to the revised Task Group number 43 recommendations, a brachytherapy source must be validated against a similar or identical source before its clinical application. The purpose of this investigation is to verify the dosimetric data of the high dose rate (HDR) BEBIG 192Ir source (Ir2.A85-2). Materials and Methods: The HDR 192Ir encapsulated seed was simulated and its main dosimetric data were calculated using Geant4 Application for Tomographic Emission (GATE) simulation code. Cubic cells were used for the calculation of dose rate constant and radial dose function while for anisotropy function ring cells were used. DoseActors were simulated and attached to the respective cells to obtain the required data. Results: The dose rate constant was obtained as 1.098 ± 0.003 cGy.h - 1.U - 1, differing by 1.0% from the reference value reported by Granero et al. Similarly, the calculated values for radial dose and anisotropy functions presented good agreement with the results obtained by Granero et al. Conclusion: The results of this study suggest that the GATE Monte Carlo code is a valid toolkit for benchmarking brachytherapy sources and can be used for brachytherapy simulation-based studies and verification of brachytherapy treatment planning systems.

A systematic review of the normal tissue complication probability models and parameters: Head and neck cancers treated with conformal radiotherapy.

This systematic review study aims to provide comprehensive data on different radiobiological models, parameters, and endpoints used for calculating the normal tissue complication probability (NTCP) based on clinical data from head and neck cancer patients treated with conformal radiotherapy. A systematic literature search was carried out according to the PRISMA guideline for the identification of relevant publications in six electronic databases of Embase, PubMed, Scopus, and Google Scholar to July 2022 using specific keywords in the paper's title and abstract. The initial search resulted in 1368 articles for all organs for the review article about the NTCP parameters. One hundred and seventy-eight articles were accepted for all organs with complete parameters for the mentioned models and finally, 20 head and neck cancer articles were accepted for review. Analysis of the studies shows that the Lyman-Kutcher-Burman (LKB) model properly links the NTCP curve parameters to the postradiotherapy endpoints. In the LKB model for esophagus, the minimum, and maximum corresponding parameters were reported as TD50 = 2.61 Gy with grade ≥3 radiation-induced esophagitis endpoints as the minimum TD50 and TD50 = 68 Gy as the maximum ones. nmin = 0.06, nmax = 1.04, mmin = 0.1, and mmax = 0.65, respectively. Unfortunately, there was not a wide range of published articles on other organs at risk like ear or cauda equina except Burman et al. (Fitting of normal tissue tolerance data to an analytic function. Int J Radiat Oncol Biol Phys Ther. 1991;21:123-135). Findings suggest that the validation of different radiobiological models and their corresponding parameters need to be investigated in vivo and in vitro for developing a more accurate NTCP model to be used for radiotherapy treatment planning optimization.

Intensity-modulated brachytherapy for vaginal cancer.

This study aimed to evaluate the dose modulation potential of static and dynamic steel-shielded applicators using the Geant4 Application for Emission Tomography (GATE) Monte Carlo code for the treatment of vaginal cancer. The GATE TOOLKIT (version 9.0) was used to simulate vaginal cancer intensity-modulated brachytherapy (IMBT) in a pelvic water-equivalent phantom. IMBT performance of a multichannel static and single-channel dynamic steel-shielded applicator was compared to that of a conventional multichannel Plexiglas applicator. DoseActors were defined to calculate the absorbed dose and attached to the voxelized target and organs at risk (OARs). 60Co and 192Ir high-dose-rate seeds were used as irradiation sources. Dynamic IMBT decreased the D2cc of the rectum and bladder by 28.67 and 28.11% using the 60Co source and by 40.00 and 36.34% using the 192Ir source, respectively. Static IMBT decreased the D2cc for the rectum and bladder by 11.69 and 9.29% using the 60Co source and by 22.21 and 17.71% using the 192Ir source, respectively. In contrast, absorbed dose parameters (D5, D90, and D100) for the target in the three techniques showed a mean relative variation of 0.96% (0.00-7.49%) for both sources. Static and dynamic IMBT using steel-shielded applicators provided relatively better OAR protection while maintaining similar target coverage in the treatment of vaginal cancer.

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.

BEBIG 60Co HDR brachytherapy source dosimetric parameters validation using GATE Geant4-based simulation code.

Purpose: This study aims to validate the dosimetric characteristics of High Dose Rate (HDR) 60Co source (Co0.A86 model) using GATE Geant4-based Monte Carlo code. According to the recommendation of the American Association of Physicists in Medicine (AAPM) task group report number 43, the dosimetric parameters of a new brachytherapy source should be verified either experimentally or by Monte Carlo calculation before clinical applications. The validated 60Co source in this study will be used for the simulation of intensity-modulated brachytherapy (IMBT) of vaginal cancer using the same GATE Geant4-based Monte Carlo code in the future. Materials and methods: GATE (version 9.0) simulation code was used to model and calculate the required TG-43U1 dosimetric data of the 60Co HDR source. DoseActors were defined for calculation of dose rate constant, radial dose function, and anisotropy function in a water phantom with an 80 cm radius. Results: The dose rate constant was obtained as 1.070 ± 0.008 cGy . h - 1 . U - 1 which shows a relative difference of 2.01% compared to the consensus value, 1.092  â€‹cGy . h - 1 . U - 1 . The calculated results of anisotropy and radial dose functions starting from 0.1 cm to 10 cm around the source showed excellent agreement with the results of published studies. The mean variation of the radial dose and anisotropy functions values from the consensus data were 1% and 0.9% respectively. Conclusion: Findings from this investigation revealed that the validation of the HDR 60Co source is feasible by the GATE Geant4-based Monte Carlo code. As a result, the GATE Monte Carlo code can be used for the verification of the brachytherapy treatment planning system.

A Borderless Solution Is Needed for A Borderless Complexity, Like COVID-19, the Universal Invader.

This chapter briefly describes the universal intricacies caused by the COVID-19 pandemic, from the ineffectiveness of distance measures, the massive economic impacts, and the severe mental health challenges to the failure of finding a vaccine, a therapeutic agent or even accurately diagnosing the infection. The entire world is suffering, but every country is trying to combat this pandemic individually, and this deed is the main barrier that prevents reaching a peaceful end.

International Efforts to Save Healthcare Personnel during COVID-19.

Coronavirus disease 2019 (COVID-19) pandemic is a global challenge. Several governments of the world have decided to take drastic actions in order to combat the spread of the disease, including the closing of air, maritime and land borders, as an extreme measure of isolation of each country/region. However, such measures had not prevented the disease from spreading globally; as COVID-19 has already spread in almost all countries. This virus's main victims are the healthcare personnel (HCP), who are physically and psychologically affected. The HCP serves as the first line of defense against this pandemic, what if we faced a significant loss in their number? And what if our HCP was going through a deep dark depression? The condition would be terrifying not only for now but also in the future. This raises the need for an intensified International collaboration, that mainly supports the HCP. We are throwing by challenging moments, and it is clear that social distancing, cooperation, hygiene awareness and abide by the recommendation and help of all governments, as well as obtaining the support of international organizations could be an excellent tool for preventing an increase in the number of cases, principally in countries and regions were COVID-19 is in the early stage of the epidemic. However, this is not the final solution for the current pandemic. An intensified global program, which mainly supports the HCP, then considers the other aspects of the COVID19 pandemic might bring this pandemic to a peaceful end.

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.