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The 2D array setup at standard measurement. The array is put between a build-up and backscatter material.
Source publication
To study the dosimetric characteristics of amorphous silicon Electronic
Portal Imaging Device EPID and 2D array detector for dose verification
of radiotherapy treatment plans, and the quality assurance QA testing of
IMRT was investigated.
Context in source publication
Context 1
... properties of 2D array and electronic portal imaging device are verified in this study. The 2D Array 1500 measurement setup used throughout this process is shown in Figure 1. For the build-up and the backscatter material, a set of RW3 polystyrene plates (PTW, Freiburg, Germany) are used. ...
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Prostate cancer treatment planning can be performed using magnetic resonance imaging (MRI) only with sCT scans. However, sCT scans are computer generated from MRI data and therefore robust, efficient, and accurate patient-specific quality assurance methods for dosimetric verification are required. Bulk anatomical density (BAD) maps can be generated...
Citations
... According to the results obtained from There are many studies comparing different dosimetric systems to evaluate gamma analysis. Ayman et al. [31] compared GI using PD and 2D array for dose verification of RT treatment plans and investigated QA. They found that the PD and 2D array was reliable and accurate dosimeter and a useful device for QA, and the values obtained with PD was more accurate compared to the 2D array. ...
Purpose: The evaluation of the agreement between calculated and measured dose plays an essential role in the quality assurance (QA) procedures of intensity-modulated radiation therapy (IMRT). This study aimed to compare gamma analysis using Portal Dosimetry (PD), Epiqa, and 2D array detector for dose verification of radiotherapy treatment plans. Materials and Methods: Five fields step-and-shoot IMRT plan was used to performed for 20 prostate IMRT patients using the dual-energy DHX linear accelerator (Varian Medical System, Palo Alto, CA, USA). The treatment plans were created using Varian DHX Eclipse treatment planning system (TPS) version 15.1. All measurements were performed by aS500 EPID integrated into Varian DHX linear accelerator and 2D array detector. The dose distribution was evaluated with gamma area histograms (GAHs) generated using different γ criteria (1%/1 mm, 2%/2 mm 3%/2 mm and 3%/3 mm) for dose agreement and distance to agreement parameters. Statistical analyses were evaluated by using Mann Whitney Test and Kruskal-Wallis Test, and p-value of p <0.01 was considered to be significant. Results: The average pass rate for 20 IMRT plans was above 95% for all devices with 2%/2 mm, 3%/2 mm and 3%/3 mm. The mean and standard deviation passing rates (γ ≤1) were found to be 99.80±0.19, 99.35±0.34 and 97.53±0.71 for PD, Epiqa and 2D array respectively. All IMRT plans passed 2%/2 mm, 3%/2 mm and 3%/3 mm gamma by more than 95% of three dosimetric systems. They are all in good agreement with the literature. Conclusion: All three devices are acceptable for quality control of IMRT. Due to the simplicity and fast evaluation process, PD can be preferred for quality control.
The goal of this study is to determine the accuracy of the PTW Beamscan program in determining the inflection point from an FFF Beam Profile utilizing Multiple Detectors. Profile measurements were taken with PTW’s 729, 1500, and 1600 and the Starcheck system, the Pinpoint 3D with Beamscan system, and Linac’s EPID. Using the first-order derivative employed in the Excel spreadsheet and Beamscan software, raw measured data were used to determine the inflection point, and the FWHM was calculated. The accuracy of inflection points and FWHM between the Excel sheet calculation and the software program were investigated. For 10X10 cm ² in the 729 Array, the greatest differences in FWHM were 5.16 mm and 5.04 mm for the X6 FFF and X10 FFF Energies, respectively. The largest difference was 2.26 mm for 1600 SRS arrays with a 15×15 cm ² field size. The difference in FWHM between Manual and software analysis for 10X10 cm ² and 20X20 cm ² Field Sizes is in decreasing order for detectors from 729, 1500, 1600 SRS, Starcheck, Pinpoint 3D, and EPID. In contrast, there is no climbing or declining pattern detected in the difference in Field Width for the 15×15 cm ² Field Size. Similarly, for all detectors except the 1600 SRS array, the peak of the first-order derivative occurs at the chamber position for a 15X15 cm ² field size. EPID outperformed all other detectors in terms of agreement with values obtained by software analysis. The data show that increased resolution improves inflection point detection. Thus, it is shown that BeamScan software is ideal for FFF beam profile analysis utilizing inflection point analysis.
This study examined the gamma passing rate (GPR) consistency during applying different kinds of gamma analyses and dosimeters to IMRT. Methods: Import treatment protocols for QA phantom irradiation have been recalculated. A gamma analysis was used for comparing the measured and calculated dose distribution of IMRT for different gamma criteria (2%/2mm, 3%/3mm, 4%/4mm, 3%/5mm, 3%/5mm). These criteria are evaluated when 5%, 10%, or 15% of the dose distribution is suppressed. Measured and calculated dose distribution was evaluated with gamma analysis to dose difference (DD) with DTA criteria (distance to agreement). IMRT QA plans to 25 patients from various sites were formed with the Varian Eclipse treatment planning system. Results: Results indicate different diverse hardware and software combinations show varied levels of agreement with expected analysis for the same pass-rate criterion. For a dosimetry audit of the IMRT technique, an EPID detector is superior to conventional methods comparable to Gafchromic EPT3 film and 2D array due to cost, time-consuming, and set up error to get result analysis. The gamma passing rate (GPR) average is increased by increasing the low-dose threshold for different dosimetric tools. For EPID, regardless of the gamma criterion employed, the %GP does not appear to be dependent on the low-dose threshold values (5%-15%) because it indicates that fulfilment the low-dose threshold to global normalization has little effect on patient-specific QA outcomes. Conclusions: It is concluded that GPRs differ depending on gamma, dosimetric tools, and the suppressing dose ratio. To get the best results of quality assurance, each institution should thus carefully develop its procedure for gamma analysis by defining the gamma index analysis and gamma criterion using its dosimetric tools.
