A case analysis of low pass rate of helical tomotherapy patient plan verification caused by air compression equipment failure(PDF)
《中国医学物理学杂志》[ISSN:1005-202X/CN:44-1351/R]
- Issue:
- 2021年第1期
- Page:
- 1-5
- Research Field:
- 医学放射物理
- Publishing date:
Info
- Title:
- A case analysis of low pass rate of helical tomotherapy patient plan verification caused by air compression equipment failure
- Author(s):
- WANG Haiyang; PI Yifei; HAN Bin; JIA Fei; WANG Fangna; LIU Lele; PEI Yuntong; HU Jinyan; KONG Fanyang; GUO Yuexin
- Department of Radiation Oncology, The First Affiliated Hospital of Zhengzhou University, Zhengzhou 450052, China
- Keywords:
- Keywords: helical tomotherapy air compression equipment verification pass rate case analysis
- PACS:
- R144.1；R811.1
- DOI:
- DOI:10.3969/j.issn.1005-202X.2021.01.001
- Abstract:
- Abstract: Objective Factors affecting the pass rate of helical tomotherapy (HT) patient plan verification were analyzed to solve the problem of low pass rate. Methods The following factors were verified and analyzed one by one: [①]The ArcCHECK scale files were recalibrated to verify the absolute dose accuracy [②]The ArcCHECK matrix calibration files were recalibrated to verify the matrix consistency [③]The dose calculation accuracy of the planning system was measured by off-line verification using open-source code of the third-party Matlab platform [④]The stability of accelerator output was verified through daily output point dose measurement and TomoDose measurement [⑤]The Jaw in-position accuracy was verified by performing the AAPM TG-148 report V.B.2.c Project and designing the conformal radiation （3DCRT） plans with the field width of 2.5 cm and 5 cm commonly used in clinical practice [⑥]The multi-leaf collimator (MLC) switching time accuracy was verified by designing 3DCRT plans and intensity-modulation radiation therapy （IMRT） plans with the field width of 2.5 cm and 5 cm commonly used in clinical practice. Results There was no significant change in the plan test pass rate after the ArcCHECK scale files calibration and matrix recalibration the Gamma pass rate of the plan obtained by off-line verification script of Matlab was above 95% the morning inspection record showed that the fixed output deviation of the accelerator was less than 2%, and the TomoDose results showed that the accelerator operated stably the results of Jaw in-position accuracy detected by implementing AAPM TG-148 report V.B.2.c project were within the error range, and Gamma test results and point dose measurement results showed no significant difference in the 3DCRT plans under the conditions of different field width of 2.5 cm and 5 cm the point dose verification error increased with the increase of target shape irregularity, plan complexity, and jaw under different plans, which proves that the accuracy of MLC switching time is the main fault factor. Conclusion After excluding a variety of influencing factors, MLC switching time accuracy caused by the failure of the air compression equipment is the main reason for the low verification pass rate after eliminating multiple contributing factors. Therefore, it is necessary to maintain the air compression equipment regularly. At the same time, the content of air compression equipment should be added in the quality assurance project performed by physicists.
Last Update: 2021-01-29