SU-E-T-98: VMAT Quality Assurance: Improving the Angular Correction Factors for Ion Chamber Arrays

2011 ◽  
Vol 38 (6Part11) ◽  
pp. 3508-3508
Author(s):  
M Kishore ◽  
J OˈDaniel ◽  
J Bowsher ◽  
F Yin
Keyword(s):  
Quality Assurance ◽  
Correction Factors ◽  
Ion Chamber ◽  
Angular Correction

scholarly journals OC-0290 Consistency of PTW30013 and FC65-G ion chamber magnetic field correction factors

2019 ◽  
Vol 133 ◽  
pp. S144-S145
Author(s):  
S. Woodings ◽  
B. Van Asselen ◽  
T. Van Soest ◽  
L. De Prez ◽  
J. Lagendijk ◽  
...  
Keyword(s):  
Magnetic Field ◽  
Correction Factors ◽  
Ion Chamber

scholarly journals Leaf Open Time Sinogram (LOTS):  A novel approach for Patient specific quality assurance of Total marrow irradiation

2020 ◽  
Author(s):  
Rajesh Thiyagarajan ◽  
Dayananda Shamurailatpam Sharma ◽  
Suryakant Kaushik ◽  
Mayur Sawant ◽  
Ganapathy Krishnan ◽  
...  
Keyword(s):  
Quality Assurance ◽  
Dose Distribution ◽  
Upper Body ◽  
Patient Specific ◽  
Reconstruction Method ◽  
Ion Chamber ◽  
Modulation Factor ◽  
Novel Approach ◽  
Open Time ◽  
Total Marrow Irradiation

Abstract There is no ideal detector-phantom combination to perform patient specific quality assurance (PSQA) for total marrow (TMI) and Lymphoid (TMLI) irradiation plan. In this study, 3D dose reconstruction using mega voltage computed tomography detectors measured leaf open time sinogram (LOTS) was investigated for PSQA of TMI/TMLI patients in helical tomotherapy. The feasibility of this method was first validated for ten non-TMI/TMLI patients, by comparing reconstructed dose with a) ion-chamber (IC) and helical detector array (ArcCheck) measurement and b) planned dose distribution using 3Dγ analysis for 3%@3mm and dose to 98%(D98%) and 2%(D2%) of PTVs. Same comparison was extended for ten treatment plans from five TMI/TMLI patients. In all non-TMI/TMLI patients, reconstructed absolute dose was within ±1.8% of planned and IC measurement. The planned dose distribution agrees with reconstructed and ArcCheck measured dose with mean(SD) 3Dγ of 98.7%(1.57%) and 2Dγ of 99.48%(0.81%). The deviation in D98% and D2% were within 1.71% and 4.1% respectively. In all 25 measurement locations from TMI/TMLI patients, planned and IC measured absolute dose agrees within ±1.2%. Although sectorial fluence verification using ArcCHECK measurement for PTVs chest from five upper body TMI/TMLI plans showed mean±SD 2Dγ of 97.82%±1.27%, the reconstruction method resulted poor mean(SD) 3Dγ of 92.00%(±5.83%), 64.80%(±28.28%), 69.20%(±30.46%), 60.80%(±19.37%) and 73.2% (±20.36%) for PTVs brain, chest, torso, limb and upper body respectively. The corresponding deviation in median D98% and D2% of all PTVs were <3.8% and 9.5%. Re-optimization of all upper body TMI/TMLI plans with new pitch and modulation factor of 0.3 and 3 leads significant improvement with 3Dγ of 100% for all PTVs and median D98% and D2% <1.6%. LOTS based PSQA for TMI/TMLI is accurate, robust and efficient. A field width, pitch and modulation factor of 5cm, 0.3 and 3 for upper body TMI/TMLI plan is suggested for better dosimetric outcome and PSQA results.

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