scholarly journals Correlation between gamma index passing rate and clinical dosimetric difference for pre-treatment 2D and 3D volumetric modulated arc therapy dosimetric verification

2015 ◽  
Vol 88 (1047) ◽  
pp. 20140577 ◽  
Author(s):  
X Jin ◽  
H Yan ◽  
C Han ◽  
Y Zhou ◽  
J Yi ◽  
...  
Keyword(s):  
Volumetric Modulated Arc Therapy ◽  
Passing Rate ◽  
Gamma Index ◽  
Arc Therapy ◽  
Pre Treatment ◽  
Dosimetric Verification ◽  
2D And 3D

Retrospective analysis of portal dosimetry pre-treatment quality assurance of prostate volumetric-modulated arc therapy (VMAT) plans

2017 ◽  
Vol 17 (1) ◽  
pp. 44-52 ◽  
Author(s):  
Borna Maraghechi ◽  
Jack Davis ◽  
Shyam Badu ◽  
Andre Fleck ◽  
Johnson Darko ◽  
...  
Keyword(s):  
Quality Assurance ◽  
Volumetric Modulated Arc Therapy ◽  
Intensity Modulated Radiation Therapy ◽  
Treatment Quality ◽  
Average Dose ◽  
Imaging Device ◽  
Passing Rate ◽  
Arc Therapy ◽  
Pre Treatment ◽  
Dose Difference

AbstractBackgroundElectronic portal imaging device (EPID) offers high-resolution digital image that can be compared with a predicted portal dose image. A very common method to quantitatively compare a measured and calculated dose distribution that is routinely used for quality assurance (QA) of volumetric-modulated arc therapy (VMAT) and intensity-modulated radiation therapy treatment plans is the evaluation of the gamma index. The purpose of this work was to evaluate the gamma passing rate (%GP), maximum gamma (γmax), average gamma (γave), maximum dose difference (DDmax) and the average dose difference (DDave) for various regions of interest using Varian’s implementation of three absolute dose gamma calculation techniques of improved, local, and combined improved and local.Methods and materialsWe analyzed 232 portal dose images from 100 prostate cancer patients’ VMAT plans obtained using the Varian EPID on TrueBeam Linacs.ResultsOur data show that the %GP, γmax and γave depend on the gamma calculation method and the acceptance criteria. Higher %GP values were obtained compared with both our current institutional action level and the American Association of Physicists in Medicine Task Group 119 recommendations.ConclusionsThe results of this study can be used to establish stricter action levels for pre-treatment QA of prostate VMAT plans. A stricter 3%/3 mm improved gamma criterion with a passing rate of 97% or the 2%/2 mm improved gamma criterion with a passing rate of 95% can be achieved without additional measurements or configurations.

Gamma-index method sensitivity for gauging plan delivery accuracy of volumetric modulated arc therapy

2015 ◽  
Vol 31 (8) ◽  
pp. 1118-1122 ◽  
Author(s):  
Jong In Park ◽  
Jong Min Park ◽  
Jung-in Kim ◽  
So-Yeon Park ◽  
Sung-Joon Ye
Keyword(s):  
Volumetric Modulated Arc Therapy ◽  
Index Method ◽  
Gamma Index ◽  
Arc Therapy ◽  
Delivery Accuracy

scholarly journals Erratum to: Effect of Minimum Segment Width on Gamma Passing Rate Considering MLC Position Error for Volumetric Modulated Arc Therapy

2019 ◽  
Vol 74 (9) ◽  
pp. 912-912
Author(s):  
Young Min Moon ◽  
Sang Il Bae ◽  
Chul Won Choi ◽  
Wan Jeon ◽  
Jin Young Kim ◽  
...  
Keyword(s):  
Volumetric Modulated Arc Therapy ◽  
Position Error ◽  
Passing Rate ◽  
Arc Therapy ◽  
Gamma Passing Rate

Effect of Minimum Segment Width on Gamma Passing Rate Considering MLC Position Error for Volumetric Modulated Arc Therapy

2019 ◽  
Vol 74 (7) ◽  
pp. 724-730
Author(s):  
Young Min Moon ◽  
Sang Il Bae ◽  
Chul Won Choi ◽  
Wan Wan Jeon ◽  
Jin Young Kim ◽  
...  
Keyword(s):  
Volumetric Modulated Arc Therapy ◽  
Position Error ◽  
Passing Rate ◽  
Arc Therapy ◽  
Gamma Passing Rate

scholarly journals Correlation Between Average Segment Width and Gamma Passing Rate as a Function of MLC Position Error in Volumetric Modulated Arc Therapy

2021 ◽  
Vol 20 ◽  
pp. 153303382110599
Author(s):  
Young Min Moon ◽  
Sang Il Bae ◽  
Moo Jae Han ◽  
Wan Jeon ◽  
Tosol Yu ◽  
...  
Keyword(s):  
Least Squares Method ◽  
Linear Regression Analysis ◽  
Volumetric Modulated Arc Therapy ◽  
Position Error ◽  
Coefficient Of Determination ◽  
Position Errors ◽  
Visual Basic For Applications ◽  
Passing Rate ◽  
Arc Therapy ◽  
Gamma Passing Rate

Objective: This study analyzed the correlation between the average segment width (ASW) and gamma passing rate according to the multi-leaf collimator (MLC) position error. Method: To evaluate the changes in the gamma passing rate according to the MLC position error, 21 volumetric modulated arc therapy (VMAT) plans were generated using pelvic lymph node metastatic prostate cancer patient's data which is sensitive to MLC position errors as they involve several long, narrow, irregular fields. The ASW for each VMAT plan was calculated using our own code developed using Visual Basic for Applications (VBA). The gamma passing rate of the VMAT plan according to the MLC position error was evaluated using ArcCHECK (Sun Nuclear, Melbourne, FL, USA) while inducing symmetric MLC position errors in 0.25 mm intervals from −1 mm to +1 mm in the infinity medical linear accelerator (Elekta AB, Stockholm, Sweden). Finally, we examined the correlation between the change in the passing rate ([Formula: see text]) due to the MLC position error and the ASW in VMAT through linear regression analysis using the least squares method. Results: The ASW and [Formula: see text] were found to have a linear correlation according to the MLC position error, and the coefficient of determination was 0.88. For a 1 mm position error of MLC in VMAT, the gamma passing rate improved by approximately 11.9% as the ASW increased by 10 mm. Conclusion: These results are expected to be employed as guidelines to minimize the dose uncertainty due to MLC position error in VMAT.

The sensitivity of gamma index analysis to detect multileaf collimator (MLC) positioning errors using Varian TrueBeam EPID and ArcCHECK for patient-specific prostate volumetric-modulated arc therapy (VMAT) quality assurance

2017 ◽  
Vol 17 (1) ◽  
pp. 66-77 ◽  
Author(s):  
Borna Maraghechi ◽  
Jack Davis ◽  
Nicholas Mitchell ◽  
Meeral Shah ◽  
Andre Fleck ◽  
...  
Keyword(s):  
Volumetric Modulated Arc Therapy ◽  
Patient Specific ◽  
Multileaf Collimator ◽  
Control Points ◽  
Dose Distributions ◽  
Positioning Errors ◽  
Gamma Index ◽  
Arc Therapy ◽  
Epid Dosimetry ◽  
Higher Sensitivity

AbstractBackgroundDue to the increased degree of modulation and complexity of volumetric-modulated arc therapy (VMAT) plans, it is necessary to have a pre-treatment patient-specific quality assurance (QA) programme. The gamma index is commonly used to quantitatively compare two dose distributions. In this study we investigated the sensitivity of single- and multi-gamma criteria techniques to detect multileaf collimator (MLC) positioning errors using the Varian TrueBeam Electronic Portal Imaging DeviceTM (EPID) dosimetry and the ArcCHECKTM device.Materials and methodsAll active MLC positions of seven intact prostate patients VMAT plans were randomly changed with a mean value of 0.25, 0.5, 1 and 2 mm and a standard deviation of 0.1 mm on 25, 50, 75 and 100% of the control points. The change in gamma passing rates of six gamma criteria of 3%/3 mm, 3%/2 mm, 3%/1 mm, 2%/2 mm, 2%/1 mm and 1%/1 mm were analysed individually (single-gamma criterion) and as a group (multi-gamma criteria) as a function of the simulated errors. We used the improved and global gamma calculation algorithms with a low dose threshold of 10% in the EPID and ArcCHECK software, respectively. The changes in the planning target volume dose distributions and the organs at risk due to the MLC positioning errors were also studied.ResultsWhen 25, 50, 75 and 100% of the control points were modified by the introduction of the simulated errors, the smallest detectable errors with the EPID were 2, 1, 0.5 and 0.5 mm, respectively, using the multi-gamma criteria technique. Similarly for the single-gamma criteria technique errors as small as 2, 1, 1 and 1 mm applied to 25, 50, 75 and 100% of the control points, respectively, were detectable using a 2%/2 mm criterion. However, the smallest detectable errors with the ArcCHECK when using the multi-gamma criteria technique were 2, 2 and 1 mm when MLC errors were applied on 50, 75 and 100% of the control points. When only 25% of the control points were affected the ArcCHECK were unable to detect any of the errors applied. No noticeable difference was observed in the sensitivity using the single- or the multi-gamma criteria techniques with the ArcCHECK.ConclusionThe Varian TrueBeam EPID dosimetry shows a higher sensitivity in detecting MLC positioning errors compared with the ArcCHECK regardless of using the single- or the multi-gamma criteria techniques. Higher sensitivity was observed using the multi-gamma criteria technique compared with the single-criterion technique when using the EPID.

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