Statistical Process Control in Monitoring Radiotherapy Quality Assurance Program: An Institutional Experience.

Document Type : Original Paper

Authors

1 Department of Physics, Noorul Islam Centre for Higher Education, Kumaracoil- 629 180, Kanyakumari District, Tamilnadu, India.

2 Department of Medical Physics and Radiation Safety, MVR Cancer Centre & Research Institute, Calicut, India

3 Department of Medical Physics and Radiation Safety, MVR Cancer Centre & Research Institute, Calicut, India

Abstract

Introduction: Statistical process control (SPC) is a handy and powerful tool for monitoring quality assurance (QA) programs in radiotherapy. This study explains the institutional experience in monitoring weekly output constancy QA and patient-specific quality assurance (PSQA) using SPC tools.
Material and Methods: Prospective monitoring of output constancy has been demonstrated by the simultaneous usage of Shewhart's I-MR charts and time-weighted control charts. PSQA results were retrospectively analysed in a combined γ and dose volume histogram (DVH) based analysis using control charts and process capability indices. A PSQA analysis method has been illustrated in which the site-specific action limits (AL) and control limits (CL) for γ and DVH based analysis were obtained using SPC.               
Results: The simultaneous use of different control charts indicated a systematic error in the output constancy of Linac as successive measurement points fell above the CL. The reason for failure was found and process was monitored further. The obtained AL and CL for γ and DVH based analysis were used to decide pass or fail criteria in PSQA. Among the analysed treatment plans, fourteen plans of different treatment sites failed the PSQA analysis. Cause-and-effect analysis of these failed treatment plans in PSQA pointed out six primary potential sources of errors in the results.
Conclusion: SPC tools can be adopted among institutions for consistent and comparable QA programs. If the QA process monitored using SPC falls outside the CL, cause-and-effect diagrams can be used to extract all possible contributing factors that lead to such a process state.

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Main Subjects

References

  1. Pawlicki T, Whitaker M, Boyer AL. Statistical process control for radiotherapy quality assurance. Medical physics. 2005;32(9):2777-86.
  2. Klein EE, Hanley J, Bayouth J, Yin FF, Simon W, Dresser S, et al. Task group 142 report: quality assurance of medical accelerators. Med Phys. 2009;36(9):4197–
  3. Sanghangthum T, Suriyapee S, Srisatit S, Pawlicki T. Retrospective analysis of linear accelerator output constancy checks using process control techniques. Journal of applied clinical medical physics. 2013;14(1):147-60.
  4. Binny D, Mezzenga E, Lancaster CM, Trapp JV, Kairn T, Crowe SB. Investigating output and energy variations and their relationship to delivery QA results using Statistical Process Control for helical tomotherapy. Physica Medica. 20171;38:105-10.
  5. Pal B, Pal A, Das S, Palit S, Sarkar P, Mondal S, et al. Retrospective study on performance of constancy check device in Linac beam monitoring using Statistical Process Control. Reports of Practical Oncology & Radiotherapy. 2020;25(1):91-9.
  6. Low DA, Harms WB, Mutic S, Purdy JA. A technique for the quantitative evaluation of dose distributions. Medical physics. 1998;25(5):656-61.
  7. Miften M, Olch A, Mihailidis D, Moran J, Pawlicki T, Molineu A, et al. Tolerance limits and methodologies for IMRT measurement‐based verification QA: recommendations of AAPM Task Group No. 218. Medical physics. 2018;45(4):e53-83.
  8. Sanghangthum T, Suriyapee S, Srisatit S, Pawlicki T. Statistical process control analysis for patient-specific IMRT and VMAT QA. Journal of radiation research. 2013;54(3):546-52.
  9. Lee R, Kim K, Cho S, Lim S, Lee S, Shim JB, et al. Statistical process control analysis for patient quality assurance of intensity modulated radiation therapy. Journal of the Korean Physical Society. 2017;71(10):717-21.
  10. Montgomery DC. Introduction to statistical quality control. Hoboken, New Jersey:John Wiley & Sons,Inc.; 2009.
  11. International Atomic Energy Agency. Absorbed dose determination in external beam radiotherapy: an international code of practice for dosimetry based on standards of absorbed dose to water, IAEA TRS-398. Vienna, Austria: IAEA, 2001.
  12. Puzhakkal N, Kochunny AK, Makuny D, MP AK, Poyil RC, Raveendran V. Validation of Dolphin dosimetry in a three dimensional patient-specific quality assurance programme. Reports of Practical Oncology & Radiotherapy. 2019;24(5):481-90.
  13. Sanghangthum T, Suriyapee S, Kim GY, Pawlicki T. A method of setting limits for the purpose of quality assurance. Physics in Medicine & Biology. 2013;58(19):7025.
  14. Yi X, Lu WL, Dang J, Huang W, Cui HX, Wu WC, et al. A comprehensive and clinical‐oriented evaluation criteria based on DVH information and gamma passing rates analysis for IMRT plan 3D verification. Journal of Applied Clinical Medical Physics. 2020;21(8):47-55.
  15. Bartolac S, Heaton R, Norrlinger B, Letourneau D. Seasonal variations in measurements of linear accelerator output. Journal of applied clinical medical physics. 2019;20(3):81-8.
  16. Grattan MW, Hounsell AR. Analysis of output trends from Varian 2100C/D and 600C/D accelerators. Physics in Medicine & Biology. 2010;56(1):N11.
  17. Chan MF, Li Q, Tang X, Li X, Li J, Tang G, Hunt MA, Deasy JO. Visual analysis of the daily QA results of photon and electron beams of a trilogy Linac over a five-year period. Int J Med Phys Clin Eng Radiat Oncol. 2015;4(4):290-9
  18. Dearnaley D, Syndikus I, Mossop H, Khoo V, Birtle A, Bloomfield D, et al. Conventional versus hypofractionated high-dose intensity-modulated radiotherapy for prostate cancer: 5-year outcomes of the randomised, non-inferiority, phase 3 CHHiP trial. The Lancet Oncology. 2016;17(8):1047-60.
  19. Alber M, Broggi C, De Wagter C et al Guidelines for the verification of IMRT. ESTRO booklet. 2008.
  20. Yi J, Han C, Zheng X, Zhou Y, Deng Z, Xie C, et al. Individual volume‐based 3D gamma indices for pre-treatment VMAT QA. Journal of Applied Clinical Medical Physics. 2017;18(3):28-36.

 

 

 

 

 

Iranian Journal of Medical Physics
Volume 19, Issue 3
May and June 2022
Pages 189-198

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History

  • Receive Date: 24 February 2021
  • Revise Date: 22 June 2021
  • Accept Date: 29 August 2021

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