Comparison Of 2D And 3D Gamma Evaluation Method In Patient Specific IMRT Quality Assurance
vinita shukla*, pawan sharma, P kumar
Abstract:
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Background:-In this study we have compared 2D and 3D gamma
pass percentage for a variety of acceptance criteria for 40 step-and-shoot IMRT plans. Material and Methods:-Treatment planning was done for 40 patient
including Head & Neck, Abdomen and pelvis simulated on the Siemens
Healthcare GmBH CT simulator with images of 3mm slice thickness using
Treatment planning system (Monaco Version 5.11.03, Elekta medical system)
using Monte Carlo algorithm.The Gamma
evaluation was done using PTW VeriSoft 8.1 which allows us to perform 2D and
3D gamma index calculation, slice-by-slice comparison of measured and
calculated dose distributions, measured dose was compared against the
calculated DICOMRT dose on the OCTAVIUS 3D phantom from TPS. Results:-
The average 3D and 2D gamma passing in coronal planes were 96.61±0.45%
and 96.27±0.78% for 5mm/5% criteria, 93.74±4.17% and 91.9±4.88% for 3mm/3%
criteria, 85.83±7.58% and 82.41±8.06% for 2mm/2% criteria and 62.8±9.42% and
59.18±9.52% for 1mm/1% criteria
respectively for all cases. The average gamma passing rate for 3D
gamma analysis was 0.35%, 1.97 %, 3.97% and 5.78 % higher when compared with
2D coronal planar analyses for 5mm/5%, 3mm/3%, 2mm/2% and 1mm/1% DTA criteria
respectively. Conclusion:
It is concluded in the study that 3 D gamma passing rate is higher
compared to 2D gamma passing for Head and Neck, abdomen and pelvis cases. Keywords: - IMRT QA, 2D gamma, 3D gamma, PSQA |