open access

Vol 25, No 1 (2020)
Original research articles
Published online: 2020-01-01
Submitted: 2019-04-23
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Retrospective study on performance of constancy check device in Linac beam monitoring using Statistical Process Control

Bipasha Pal, Angshuman Pal, Suresh Das, Soura Palit, Papai Sarkar, Subhayan Mondal, Suman Mallik, Jyotirup Goswami, Sayan Das, Arijit Sen, Monidipa Mondol
DOI: 10.1016/j.rpor.2019.12.004
·
Rep Pract Oncol Radiother 2020;25(1):91-99.

open access

Vol 25, No 1 (2020)
Original research articles
Published online: 2020-01-01
Submitted: 2019-04-23

Abstract

Aim

To examine the application of Statistical Process Control (SPC) and Ishikawa diagrams for retrospective evaluation of machine Quality Assurance (QA) performance in radiotherapy

Background

SPC is a popular method for supplementing the performance of QA techniques in healthcare. This work investigates the applicability of SPC techniques and Ishikawa charts in machine QA.

Materials and Methods

SPC has been applied to recommend QA limits on the particular beam parameters using the QUICKCHECKwebline QA portable constancy check device for 6[[!--[[Diff id="80"/]]--]]MV and 10MV flattened photon beams from the Elekta Versa HD linear accelerator (Linac). Four machine QA parameters – beam flatness, beam symmetry along gun target direction and left-right direction, and beam quality factor (BQF) – were selected for retrospective analysis. Shewhart charts, Exponentially Weighted Moving Average (EWMA) charts and Cumulative Sum (CUSUM) charts were obtained for each parameter. The root causes for a failure in machine QA were broken down into an Ishikawa diagram enabling the user to identify the root cause of error and rectify the problem subsequently.

Results

Shewhart charts and EWMA charts applied could detect loss in control in one variable in the 6[[!--[[Diff id="81"/]]--]]MV beams and in all four variables in 10[[!--[[Diff id="82"/]]--]]MV beams. CUSUM charts detected offsets in the readings. The Ishikawa chart exhaustively included the possible errors that lead to loss of control.

Conclusion

SPC is proven to be effective for detection of loss in control in machine QA. The Ishikawa chart provides the set of probable root causes of machine error useful while troubleshooting.

Abstract

Aim

To examine the application of Statistical Process Control (SPC) and Ishikawa diagrams for retrospective evaluation of machine Quality Assurance (QA) performance in radiotherapy

Background

SPC is a popular method for supplementing the performance of QA techniques in healthcare. This work investigates the applicability of SPC techniques and Ishikawa charts in machine QA.

Materials and Methods

SPC has been applied to recommend QA limits on the particular beam parameters using the QUICKCHECKwebline QA portable constancy check device for 6[[!--[[Diff id="80"/]]--]]MV and 10MV flattened photon beams from the Elekta Versa HD linear accelerator (Linac). Four machine QA parameters – beam flatness, beam symmetry along gun target direction and left-right direction, and beam quality factor (BQF) – were selected for retrospective analysis. Shewhart charts, Exponentially Weighted Moving Average (EWMA) charts and Cumulative Sum (CUSUM) charts were obtained for each parameter. The root causes for a failure in machine QA were broken down into an Ishikawa diagram enabling the user to identify the root cause of error and rectify the problem subsequently.

Results

Shewhart charts and EWMA charts applied could detect loss in control in one variable in the 6[[!--[[Diff id="81"/]]--]]MV beams and in all four variables in 10[[!--[[Diff id="82"/]]--]]MV beams. CUSUM charts detected offsets in the readings. The Ishikawa chart exhaustively included the possible errors that lead to loss of control.

Conclusion

SPC is proven to be effective for detection of loss in control in machine QA. The Ishikawa chart provides the set of probable root causes of machine error useful while troubleshooting.

Get Citation

Keywords

Radiotherapy; Quality assurance; Statistical process control; Shewhart chart; Ishikawa diagram

About this article
Title

Retrospective study on performance of constancy check device in Linac beam monitoring using Statistical Process Control

Journal

Reports of Practical Oncology and Radiotherapy

Issue

Vol 25, No 1 (2020)

Pages

91-99

Published online

2020-01-01

DOI

10.1016/j.rpor.2019.12.004

Bibliographic record

Rep Pract Oncol Radiother 2020;25(1):91-99.

Keywords

Radiotherapy
Quality assurance
Statistical process control
Shewhart chart
Ishikawa diagram

Authors

Bipasha Pal
Angshuman Pal
Suresh Das
Soura Palit
Papai Sarkar
Subhayan Mondal
Suman Mallik
Jyotirup Goswami
Sayan Das
Arijit Sen
Monidipa Mondol

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