Abstract：Objective To analyze the influence of MLC (Multi-Leaf Collimator) position error on the
verification pass rate of IMRT (Intensity-Modulated Radiation Therapy) plan through experiments. Methods
Altogether 8 cases of nasopharyngeal carcinoma IMRT plans were selected. And then, for each case, the
errors of ±0.5 mm, ±1 mm and ±2 mm in MLC leaf terminal positions were set respectively through the
program system, which was named as Trail-0.5, Trail+0.5, Trail-1, Trail+1, Trail-2 and Trail+2 respectively.
Each program was measured by using Octavius 4D dose verification system to obtain all the three dimensional
dose distribution of each plan. And the dose verification pass rate of all the plans was acquired by using the
gamma analysis method. Results When the evaluation index was 2%/2 mm, the average pass rate of 8 cases
was 76.3%. The pass rate of Trail-1, Trail-2 and Trail+2 were less than that of the original plan. But only the
average pass rate of Trail+2 had statistical significance (P<0.05) in contrast with the original plan. When the
evaluation index was 3%/3 mm, the average pass rate of 8 cases was 91.7%. Similar to 2%/2 mm, the pass rate
of Trail-1, Trail-2 and Trail+2 was less than that of the original plan; only the average pass rate of trail+2 had
statistical significance (P<0.05) in contrast with the original plan. Conclusion The location precision of MLC
need independent quality control to ensure the accurate implementation of radiotherapy.
王猛. 多叶准直器位置误差对静态野调强放疗计划验证通过率影响的研究[J]. 中国医疗设备, 2016, 31(10): 106-107.
WANG Meng. Study on the Influence of Multi-leaf Collimator Position Error on the
Verification Pass Rate of the Static IMRT Plan. China Medical Devices, 2016, 31(10): 106-107.
