scholarly journals Analysis of gamma index using in-house developed heterogeneous thorax phantom

2021 ◽  
Vol 8 (1) ◽  
pp. 9-11
Author(s):  
Priyusha Bagdare ◽  
Swati Dubey ◽  
Sanjay Kumar Ghosh ◽  
Shital Bhandigare
Keyword(s):  
Intensity Modulated Radiotherapy ◽  
Patient Treatment ◽  
Patient Specific ◽  
Uniform Density ◽  
Electronic Portal Imaging Device ◽  
Imaging Device ◽  
Simple Geometry ◽  
Gamma Index ◽  
Gamma Evaluation ◽  
Pre Treatment

Quality assurance (QA) before patient treatment plays a major role in complex radiotherapy (RT) treatment planning. Phantoms are the standard materials that are used for the pre-treatment QA of patients. Contemporary phantoms used in RT are mainly water-based, having simple geometry and of uniform density. These phantoms dose not replicate the exact heterogeneities of the actual human body. The present work aims to evaluate the results of relative dosimetry performed on in-house developed heterogeneous thorax phantom (HTP) using an electronic portal imaging device (EPID). To perform the relative dosimetry, contours were drawn on HTP at three different locations and intensity modulated radiotherapy (IMRT), as well as Rapid ARC (RA), were generated on it to compare the fluence obtained on TPS as well as on linac machine. The gamma evaluation results indicate a strong correlation between planned and the measured fluence. We found the EPID-based QA done on HTP explore its property as a QA tool and it can further be used to perform patient-specific relative dosimetry.

Quality assurance of linear accelerator: a comprehensive system using electronic portal imaging device

2018 ◽  
Vol 18 (02) ◽  
pp. 138-149
Author(s):  
P. Niyas ◽  
K. K. Abdullah ◽  
M. P. Noufal ◽  
R. Vysakh
Keyword(s):  
Quality Assurance ◽  
Linear Accelerator ◽  
Planning System ◽  
Treatment Planning System ◽  
Patient Specific ◽  
Array Detector ◽  
Electronic Portal Imaging Device ◽  
Imaging Device ◽  
Portal Imaging ◽  
Electronic Portal Imaging

AbstractAimThe Electronic Portal Imaging Device (EPID), primarily used for patient setup during radiotherapy sessions is also used for dosimetric measurements. In the present study, the feasibility of EPID in both machine and patient-specific quality assurance (QA) are investigated. We have developed a comprehensive software tool for effective utilisation of EPID in our institutional QA protocol.Materials and methodsPortal Vision aS1000, amorphous silicon portal detector attached to Clinac iX—Linear Accelerator (LINAC) was used to measure daily profile and output constancy, various Multi-Leaf Collimator (MLC) checks and patient plan verification. Different QA plans were generated with the help of Eclipse Treatment Planning System (TPS) and MLC shaper software. The indigenously developed MATLAB programs were used for image analysis. Flatness, symmetry, output constancy, Field Width at Half Maximum (FWHM) and fluence comparison were studied from images obtained from TPS and EPID dosimetry.ResultsThe 3 years institutional data of profile constancy and patient-specific QA measured using EPID were found within the acceptable limits. The daily output of photon beam correlated with the output obtained through solid phantom measurements. The Pearson correlation coefficients are 0.941 (p = 0.0001), 0.888 (p = 0.0188) and 0.917 (p = 0.0007) for the years of 2014, 2015 and 2016, respectively. The accuracy of MLC for shaping complex treatment fields was studied in terms of FWHM at different portions of various fields, showed good agreement between TPS-generated and EPID-measured MLC positions. The comparison of selected patient plans in EPID with an independent 2D array detector system showed statistically significant correlation between these two systems. Percentage difference between TPS computed and EPID measured fluence maps calculated for number of patients using MATLAB code also exhibited the validity of those plans for treatment.

scholarly journals A Retrospective Study of Commercial Software System EDose in QA Application based on the Electronic Portal Imaging Device

2021 ◽  
Author(s):  
Xiaojuan Duan ◽  
Hongya Dai ◽  
Yongqin Li ◽  
Yibing Zhou
Keyword(s):  
Electronic Portal Imaging Device ◽  
Dose Verification ◽  
Commercial Software ◽  
Imaging Device ◽  
Portal Imaging ◽  
Electronic Portal Imaging ◽  
Passing Rates ◽  
Treatment Dose ◽  
Pre Treatment

Abstract Purpose: To evaluate the functions about the pre-treatment dose verification and, the in vivo dose verification for the commercial software EDose system based on Electronic Portal Imaging Device (EPID) retrospectively and establish the action limit level. Methods: The results of pre-treatment dose verification were compared with 2D array Seven29 and 3Dmap for 50 randomly selected IMRT plans of different lesions. A retrospective analysis was conducted for 287 radiotherapy plans using the EDose in pre-treatment dose verification, including 53 IMRT and 247 RapidArc plans, to establish the action limit level with statistical significance evaluation. 28 head and neck patients with different lesions were selected randomly for studying 3D online dose verification preliminary.Results: For pre-treatment dose verification, 50 plans’ average γ passing rates of the 3%/3mm criterion were > 98% for EDose, Seven29, 3Dmap, and 3%/2mm, 2%/2mm criteria were > 95%, 90%. The average γmean of the three verification methods were similar for the 3%/3mm criterion (0.35, 0.38, 0.35). Based on the 287 patients’ clinical data, the average γ passing rate was 97.5%, and the recommend clinical action level was established at 92% with a 95% confidence limit. The in vivo results showed that the γ pass rate had a decreasing trend as the 33 treatment fractions progressed. The γ passing rates means±SD of the first fraction was (91.92±3.31)% while the 33th fraction was (85.73±8.75)%. In addition, the standard deviation between the TPS calculations and the EDose measurement results indicated a higher value of the thirty-third treatment for PTVs and organ at risk compared to the first treatment.Conclusions: This study demonstrated that the EDose system is an accurate, efficient method for quality assurance of patient’ radiotherapy plans with remarkable consistency of treatment planning system (TPS).

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