scholarly journals Effect of Multileaf Collimator Leaf Position Error Determined by Picket Fence Test on Gamma Index Value in Patient-Specific Quality Assurance of Volumetric-Modulated Arc Therapy Plans

Cureus ◽  
2021 ◽  
Author(s):  
Cemile Ceylan ◽  
Serpil Yondem Inal ◽  
Elif Senol ◽  
Berrin Yilmaz ◽  
Sevim Sahin
Keyword(s):  
Quality Assurance ◽  
Volumetric Modulated Arc Therapy ◽  
Position Error ◽  
Patient Specific ◽  
Multileaf Collimator ◽  
Leaf Position ◽  
Picket Fence ◽  
Gamma Index ◽  
Arc Therapy ◽  
Index Value

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.

scholarly journals A study on the correlation between plan complexity and gamma index analysis in patient specific quality assurance of volumetric modulated arc therapy

2015 ◽  
Vol 20 (1) ◽  
pp. 57-65 ◽  
Author(s):  
Dhanabalan Rajasekaran ◽  
Prakash Jeevanandam ◽  
Prabakar Sukumar ◽  
Arulpandiyan Ranganathan ◽  
Samdevakumar Johnjothi ◽  
...  
Keyword(s):  
Quality Assurance ◽  
Volumetric Modulated Arc Therapy ◽  
Patient Specific ◽  
Index Analysis ◽  
Gamma Index ◽  
Arc Therapy

scholarly journals Feasibility Study of Mobius3D for Patient-Specific Quality Assurance in the Volumetric Modulated Arc Therapy

2019 ◽  
Vol 30 (4) ◽  
pp. 120
Author(s):  
Chang Yeol Lee ◽  
Woo Chul Kim ◽  
Hun Jeong Kim ◽  
Jeongshim Lee ◽  
Hyun Do Huh
Keyword(s):  
Quality Assurance ◽  
Feasibility Study ◽  
Volumetric Modulated Arc Therapy ◽  
Patient Specific ◽  
Arc Therapy
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