Assessment of Multi-leaf Collimator Positional Accuracy Using Radiochromic EBT3 Film and an Electronic Portal Imaging Device

This study aimed to evaluate multi-leaf collimator (MLC) positional accuracy by using an electronic portal imaging device (EPID) and radiochromic EBT3 film. Furthermore, the MLC�s positional accuracy at different gantry and collimator angles of a Siemens ONCOR linear accelerator (linac) was evaluated. A picket fence test was performed to evaluate the MLC�s positional accuracy at various gantry and collimator angles of the linac. The EPID and the EBT3 films were sequentially irradiated seven times at 2-cm intervals by making a rectangular field (0.3 � 19 cm2). The full-width at half-maximum (FWHM) of each band (field) was calculated for all leaves by using inhouse software. Then, variations between the actual and the planned leaf locations were obtained by using the EPID and the EBT3 film at various gantry and collimator angles. The mean FWHM, acquired using the EPID and the EBT3 film ranged from 2.331 - 3.647 mm and 2.059 - 4.001 mm, respectively. Variations between the actual and the planned leaf locations were found to be affected by changes in the collimator and the gantry angles. Moreover, a -0.060 - 1.588 mm difference we seen between the result obtained from the EBT3 film and that obtained from the EPID. The mean FWHM, at most angles, for the EBT3 film was larger than that for the EPID. The findings showed average deviations for the EPID (0.001 - 0.669 mm) and EBT3 film (0.007 - 1.001 mm); these values agreed within the tolerance level (±1 mm). Furthermore, good agreement was found between the results obtained from the EPID and the EBT3 film; these two dosimetric methods can be used interchangeably, but each must be chosen considering its advantages and disadvantages. © 2020, The Korean Physical Society

The use of EBT3 film and Delta4 for the dosimetric verification of EclipseTM treatment planning system in a heterogeneous chest phantom: An IMRT technique

Background: This study aimed to evaluate the dose calculation accuracy of EclipseTM treatment planning system (TPS) in a heterogeneous chest phantom with the intensity modulated radiotherapy (IMRT) technique using EBT3 film and Delta4. Materials and Methods: Two IMRT plans (A and B) were prepared for radiotherapy of the heterogeneous chest phantom. Plan A was between the left lung and the surrounding soft tissue and plan B was carried out on the soft tissue. EBT3 film and Delta4 were used for dose measurement in the phantom. EclipseTM TPS was also used for dose calculation. Finally, the gamma index values of the TPS with film and TPS with Delta4 were obtained. A 95 passing rate of gamma index with the passing criterion of 3mm/3 and a dose threshold of 20 as the standard criterion was considered in this study. Furthermore, the passing rates of gamma indices of the film and Delta4 were compared with each other via Bland-Altman analysis. Results: The mean passing rate of gamma index with standard passing criterion between the TPS calculations and film measurements was 96.95±0.22, while it was equal to 97.7±0.56 and 98.45±0.21 between the TPS calculations and 2D and 3D Delta4 measurements, respectively. Additionally, the differences between the passing rates of gamma indices of the film and Delta4 were less than 5. Conclusion: The findings demonstrate that the accuracy of dose calculations of EclipseTM TPS in a heterogeneous chest phantom with the IMRT technique is within the standard passing criterion. Furthermore, it can be concluded that there is a good agreement between the film and Delta4, as IMRT QA devices. © 2019 Novin Medical Radiation Institute. All rights reserved

Registry Data Coordinator (RDC): A proper accessible strategy for improving Road Traffic Injury (RTI) Hospital Based Trauma Registry Systems in developing countries and low income countries

Abstract Introduction: Evidence suggested that a significant level of trauma mortality can be prevented using registry system. Aim: This study aimed to improve Kashan Hospital Based Trauma Registry System (KHBTRS) for Road Traffic Injury (RTI). Material and methods: After conducting focus group discussion absence of minimum data set (MDS) and poor data collection process (DCP) were identified as main problems for KHBTRS- RTI. Proposed MDS were surveyed by 20 experts of trauma research center of throughout the Iran. Then approved MDS applied for trauma registry system data base in form of SQL. DCP were reform from prospective data collection (review of medical record) to concurrent (through the interview) approach. Results: Most of participants for MDS approval belonged to clinical group 13(65%). 146 MDS in eighteen main categories were proposed for RTI. The maximum score for each MDS main categories were attributed to body parts injured 220 (100%) and patient vital signs 139 (99.29%) respectively. Pilot testing of KHBTRS- RTI database of 50 (50%) riders indicated fully completeness 50 (100%) for concurrent approach. It was concluded that based on experts’ viewpoints MDS relating to injury nature and place of occurrence have more priority in comparisons to MDS relating to causes of injury. It may attribute to health care providers focus on clinical care and treatment. Conclusion: It was concluded that based on experts’ viewpoints MDS relating to injury nature and place of occurrence have more priority in comparisons to MDS relating to RTI prevention; it may attribute to health care providers focus on clinical care and treatment. To develop injury interventions based on given data, recruitment of professionals as registry data coordinator with specific job description to collect and advocacy of injury external causes data seems imperative. Keywords: data collection, registries, trauma, road traffic accident, data completeness, World Health Organizatio

Thermal distribution in ablation of squamous cell carcinoma skin tumors using irreversible electroporation

Background and Objective: Irreversible electroporation is a new treatment modality for skin tumors ablation. In order to successful treatment, all of tumoral tissues must be exposed to intense electric field. In addition, the heat that produced during the surgery has adverse effect on recovery procedure. This study was done to evaluate the thermal distribution in ablation of squamous cell carcinoma skin tumors using irreversible electroporation. Materials and Methods: In this study numerical modeling by finite element was used for determination of electrical and thermal distribution in healthy and tumoral tissues. Three-Dimensional Model was done using MR imaging of patient with squamous cell carcinoma in FEMLAB v3.5a software. Electric field distribution determined using Laplace equation and distribution of thermal damage calculated using bioheat equation and Arrhenius equation. This calculation was done for different geometry parameters of needle and plate electrodes. Results: Thermal damage of first-degree burn was not observed in any cases. However in high voltage, volume with temperature above 43˚C reach to 10% of tumoral tissue and 3% of healthy tissue. The study show that the voltage applied to the electrodes and the distance between the electrodes can have the greatest impact on the thermal and electrical distributions. Although needle electrode showed better electric coverage in tumoral area. Conclusion: This study showed that it can be possible to select optimized electric and geometric parameter to select electrode for complete tumor ablation, control of thermal damage in tumoral and healthy tissues

A Feasibility Study of IMRT of Lung Cancer Using Gafchromic EBT3 Film

Background: Intensity modulated radiation therapy (IMRT) is an advanced method for delivery of three dimensional therapies, which provides optimal dose distribution with giving multiple nonuniform fluency to the patient. The complex dose distribution of IMRT should be checked to ensure that the accurate dose is delivered. Today, film dosimetry is a powerful tool for radiotherapy treatment Quality Assurance (QA) and a good method to verify dose distribution in phantoms. Objective: This study aimed to evaluate the accuracy of IMRT treatment planning system, Prowess Panther® software, with Gafchromic EBT3 films in a inhomogeneity phantom Method: The IMRT plan was generated by Prowess Panther® treatment planning system (TPS) version 5.2 on a inhomogeneity phantom, then it was irradiated by ONCOR linear accelerator (Linac) with 6 (MV) photon beam energy. The Gafchromic EBT3 film located between the phantom has measured the dose distribution.­ To compare between TPS calculated doses and film measured doses, Gamma criteria 3%/3 mm, 4%/4 mm, 5%/5 mm, 6%/6 mm and 7%/7 mm Dose Difference (DD) and Distance to Agreement (DTA), respectively were used. Results: Gammas passing rates for PTV are obtained 67.5% for 3%/3mm, 78.8% for 4%/4mm, 86.3% for 5%/5mm, 91.2% for 6%/6mm and 94.3% for 7%/7mm and for organs at risk is 72.4% for 3%/3mm, 82.8% for 4%/4mm, 89.8% for 5%/5mm, 93.3% for 6%/6mm and 95.4% for 7%/7mm (respectively DD/DTA). By increasing the range of criteria the capability increased. Conclusion: The results show that the use of EBT3 film in a inhomogeneity phantoms allows us to evaluate the dose differences between the EBT3 measured dose distribution and TPS calculated dose distribution .Hence, a result Prowess Panther® TPS can be used for IMRT technique treatment

Benchmarking of Monte Carlo model of Siemens Oncor® linear accelerator for 18MV photon beam: Determination of initial electron beam parameters

OBJECTIVE: This study aims to benchmark a Monte Carlo (MC) model of the 18 MV photon beam produced by the Siemens Oncor® linac using the BEAMnrc and DOSXYZnrc codes. METHODS: By matching the percentage depth doses and beam profiles calculated by MC simulations with measurements, the initial electron beam parameters including electron energy, full width at half maximum (spatial FWHM), and mean angular spread were derived for the 10×10 cm2 and 20×20 cm2 field sizes. The MC model of the 18 MV photon beam was then validated against the measurements for different field sizes (5×5, 30×30 and 40×40 cm2) by gamma index analysis. RESULTS: The optimum values for electron energy, spatial FWHM and mean angular spread were 14.2 MeV, 0.08 cm and 0.8 degree, respectively. The MC simulations yielded the comparable measurement results of these optimum parameters. The gamma passing rates (with acceptance criteria of 1/1 mm) for percentage depth doses were found to be 100 for all field sizes. For cross-line profiles, the gamma passing rates were 100, 97, 95, 96 and 95 for 5×5, 10×10, 20×20, 30×30 and 40×40 cm2 field sizes, respectively. CONCLUSIONS: By validation of the MC model of Siemens Oncor® linac using various field sizes, it was found that both dose profiles of small and large field sizes were very sensitive to the changes in spatial FWHM and mean angular spread of the primary electron beam from the bending magnet. Hence, it is recommended that both small and large field sizes of the 18 MV photon beams should be considered in the Monte Carlo linac modeling. © 2019-IOS Press and the authors. All rights reserved

Benchmarking of Monte Carlo model of Siemens Oncor® linear accelerator for 18MV photon beam: Determination of initial electron beam parameters

OBJECTIVE: This study aims to benchmark a Monte Carlo (MC) model of the 18 MV photon beam produced by the Siemens Oncor® linac using the BEAMnrc and DOSXYZnrc codes. METHODS: By matching the percentage depth doses and beam profiles calculated by MC simulations with measurements, the initial electron beam parameters including electron energy, full width at half maximum (spatial FWHM), and mean angular spread were derived for the 10�10 cm2 and 20�20 cm2 field sizes. The MC model of the 18 MV photon beam was then validated against the measurements for different field sizes (5�5, 30�30 and 40�40 cm2) by gamma index analysis. RESULTS: The optimum values for electron energy, spatial FWHM and mean angular spread were 14.2 MeV, 0.08 cm and 0.8 degree, respectively. The MC simulations yielded the comparable measurement results of these optimum parameters. The gamma passing rates (with acceptance criteria of 1/1 mm) for percentage depth doses were found to be 100 for all field sizes. For cross-line profiles, the gamma passing rates were 100, 97, 95, 96 and 95 for 5�5, 10�10, 20�20, 30�30 and 40�40 cm2 field sizes, respectively. CONCLUSIONS: By validation of the MC model of Siemens Oncor® linac using various field sizes, it was found that both dose profiles of small and large field sizes were very sensitive to the changes in spatial FWHM and mean angular spread of the primary electron beam from the bending magnet. Hence, it is recommended that both small and large field sizes of the 18 MV photon beams should be considered in the Monte Carlo linac modeling. © 2019-IOS Press and the authors. All rights reserved