The feasibility study of independent check for intensity-modulated radiotherapy

Objective: To investigate of the accuracy and feasibility of independent check for intensity-modulated radiotherapy (IMRT). Methods: Inputting the linear accelerator Varian 600C/D physical data to IMsure ( a independent checking software) and constructing a calculation model. Use of IMsure to calculate the point dose and fluence of 25 cases IMRT treatment plans which have been calculated by Eclipse treatment planning system (TPS), and do a actual measurement of these plans by Matrixx at the same time. IMsure, TPS calculation results and measurement results of Matrixx were compared. Results: Select Matrixx's center probe as a reference point, to TPS calculated results as the standard,then the average difference of the IMsure calculation and Matrixx measurement were (-0.13 ± 1.24)% (t =0.20, P =0.840) and (- 0.18 ± 1.45) % (t =0.86, P =0.400), respectively. Compared IMsure with 3 mm/3% and 2 mm/2% standard respectively, the average γ rate of TPS were (98.7 ±2.8)% and (94.9 ±7.2)%; compared matrixx measurement results, the average γ rate of TPS were ( 99.0 ± 2.0 )% and ( 93.2 ±6.9)%. The results show that the difference of the point dose and the γ rate of dose distribution by Matrixx measurement and IMsure calculation was no statistically significant difference (t =1.54, P =0.126). Conclusions: Independent checking software can be used in the treatment planning system to acceptance and initial clinical tests. In routine, a independent checking software as IMsure may do a 'pre-verification' of IMRT treatment plan, or even partially replace of the actual measurement if the adequate conventional quality assurance do well, thus reducing the daily measurements. (authors)