Author: Wenwen Bai 👨🔬
Affiliation: The Fourth Hospital of Hebei Medical University 🌍
Purpose: To compare three kind of solutions (EDR2 Film, MatriXX, COMPASS) for VMA quality assurance at head and Neck in Monaco plannig system.
Methods: Monacao 5.1 planning system optimazed 10 cases of head and Neck cancer VMAT palns (4 cases of nasopharyngeal carcinoma, 3 cases cancer of larynx and 3 cases of oral cavity). Then they were measuured in Homogeneous thoracal phantom (CIRS Model 002H5 ) using Kodak EDR2 and Gafchromic Films and ion chamber (PTW-Freiburg, 0.3 cm³) for one dimensional dose verification, and using MatriXX (2D-array in phantom) and COMPASS (2D-array with gantry holder) detector array for two dimensional dose verification. Profile, Gamma Index (3%,3mm) for different pass and fail criteria and pixel count are analysed. The threshold values of 3%,3mm, to compared the result of Gamma pass rate.
Results: The passrate of COMPASS was higher than the Matrixx and film can reached to 99.44%±0.24, one dimensional film dose verification has the lowest passrate only 89.55%±3.15. For 2D-array MatriXX without or with lateral correction the Gamma passrate can be changed from 92.56%±3.47 to 95.39%±1.65.
Conclusion: For Head and Neck cancer patient’s VMAT plans, using 2D-array MatriXX dose verification,do lateral correction is recommend. And COMPASS dose verification are generally higer than one dimensional film dose verification Gamma pass rate. This point should to noted for head and neck patient with VMAT plan verification.