2Department of Medical Physics, Kalyan Singh Super Specialty Cancer Institute, Lucknow-India
3Department of Radiotherapy, Sanjay Gandhi Postgraduate Institute of Medical Sciences, Lucknow-India DOI : 10.5505/tjo.2024.4447 OBJECTIVE
The complexities associated with RapidArc in treatment planning and delivery have always required pre-treatment quality assurance (PSQA). This study aimed to compare the PSQA results of Fraction- Lab, a phantom-free log file analysis, with 2D array and portal dosimetry (PD) to evaluate appropriate gamma criteria.
METHODS
Thirty treatment plans each from Head and Neck (H&N) and pelvis sites were analyzed. FractionLab (Varian/
Mobius Medical System) was used for phantom-free gamma analysis of delivered and planned fluences
based on log files. PD was performed using an aS1200 EPID, and 3D gamma analysis was conducted using
the Octavius 4D 1500 2D detector array. Gamma evaluation in FractionLab was performed using log files
from 0.1%/0.1 mm to 1%/1 mm in increments of 0.1%/0.1 mm and compared with global gamma criteria.
RESULTS
The average gamma passing rates for H&N and pelvis sites using portal dosimetry, the 2D array (3%/2
mm), and FractionLab were 98.68% and 98.17%; 96.79% and 98.79%; 98.31% and 98.02% at 0.5%/0.5
mm, respectively. The portal dosimetry results (3%/2 mm) were statistically comparable with Fraction-
Lab (0.4%/0.4 mm-0.7%/0.7 mm).
CONCLUSION
This study demonstrated the performance and suitability of gamma criteria for FractionLab in a phantom-
free PSQA settingand it can serve as a reliable second check for PSQA.