Plan evaluation and dosimetric comparison of IMRT using AAPM TG119 test suites and recommendations

In order to verify intensity modulated radiotherapy quality assurance procedure and to establish the practical base line commissioning, American Association of Physicists in Medicine-Task Group 119 test suite DICOM-RT images and structure were downloaded for planning and dosimetric comparison. The square slab phantom of water equivalent plastic was used for the measurement. This phantom can permit point dose measurement with ionization chamber by placing the chamber at 7.5 cm depth in the slab phantom. The planar dose measurements were carried out by positioning the Matrixx detector at 10 cm depth. The planning and measurements were performed as per AAPM TG119 guidelines. The test suite includes AP:PA field, band test, multitarget, prostate, head and neck and C-shape. The ion chamber measurements were within 3% of the planned dose for target and avoidance structure region. The ion chamber measurement results are in good agreement with the TG119 recommendation of ±3% for all the test suites. The planar dose measurements were performed with Matrixx for individual fields at the planned gantry angle. The results show that the pass criteria for γ ≤ 1 were between 93 to 97% for all the test cases. Our results are in good agreement with the TG119 recommendation. The present study aimed to compare the measured dose with the planned dose using computer planning system. The test suites were used to assess the planning and delivery systems so as to provide the basis for IMRT commissioning and QA.