Cargando…
Statistical process control and verifying positional accuracy of a cobra motion couch using step‐wedge quality assurance tool
This study utilizes process control techniques to identify action limits for TomoTherapy couch positioning quality assurance tests. A test was introduced to monitor accuracy of the applied couch offset detection in the TomoTherapy Hi‐Art treatment system using the TQA “Step‐Wedge Helical” module and...
Autores principales: | , , , |
---|---|
Formato: | Online Artículo Texto |
Lenguaje: | English |
Publicado: |
John Wiley and Sons Inc.
2017
|
Materias: | |
Acceso en línea: | https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5874965/ https://www.ncbi.nlm.nih.gov/pubmed/28730740 http://dx.doi.org/10.1002/acm2.12136 |
_version_ | 1783310271247286272 |
---|---|
author | Binny, Diana Lancaster, Craig M. Trapp, Jamie V. Crowe, Scott B. |
author_facet | Binny, Diana Lancaster, Craig M. Trapp, Jamie V. Crowe, Scott B. |
author_sort | Binny, Diana |
collection | PubMed |
description | This study utilizes process control techniques to identify action limits for TomoTherapy couch positioning quality assurance tests. A test was introduced to monitor accuracy of the applied couch offset detection in the TomoTherapy Hi‐Art treatment system using the TQA “Step‐Wedge Helical” module and MVCT detector. Individual X‐charts, process capability (cp), probability (P), and acceptability (cpk) indices were used to monitor a 4‐year couch IEC offset data to detect systematic and random errors in the couch positional accuracy for different action levels. Process capability tests were also performed on the retrospective data to define tolerances based on user‐specified levels. A second study was carried out whereby physical couch offsets were applied using the TQA module and the MVCT detector was used to detect the observed variations. Random and systematic variations were observed for the SPC‐based upper and lower control limits, and investigations were carried out to maintain the ongoing stability of the process for a 4‐year and a three‐monthly period. Local trend analysis showed mean variations up to ±0.5 mm in the three‐monthly analysis period for all IEC offset measurements. Variations were also observed in the detected versus applied offsets using the MVCT detector in the second study largely in the vertical direction, and actions were taken to remediate this error. Based on the results, it was recommended that imaging shifts in each coordinate direction be only applied after assessing the machine for applied versus detected test results using the step helical module. User‐specified tolerance levels of at least ±2 mm were recommended for a test frequency of once every 3 months to improve couch positional accuracy. SPC enables detection of systematic variations prior to reaching machine tolerance levels. Couch encoding system recalibrations reduced variations to user‐specified levels and a monitoring period of 3 months using SPC facilitated in detecting systematic and random variations. SPC analysis for couch positional accuracy enabled greater control in the identification of errors, thereby increasing confidence levels in daily treatment setups. |
format | Online Article Text |
id | pubmed-5874965 |
institution | National Center for Biotechnology Information |
language | English |
publishDate | 2017 |
publisher | John Wiley and Sons Inc. |
record_format | MEDLINE/PubMed |
spelling | pubmed-58749652018-04-02 Statistical process control and verifying positional accuracy of a cobra motion couch using step‐wedge quality assurance tool Binny, Diana Lancaster, Craig M. Trapp, Jamie V. Crowe, Scott B. J Appl Clin Med Phys Radiation Oncology Physics This study utilizes process control techniques to identify action limits for TomoTherapy couch positioning quality assurance tests. A test was introduced to monitor accuracy of the applied couch offset detection in the TomoTherapy Hi‐Art treatment system using the TQA “Step‐Wedge Helical” module and MVCT detector. Individual X‐charts, process capability (cp), probability (P), and acceptability (cpk) indices were used to monitor a 4‐year couch IEC offset data to detect systematic and random errors in the couch positional accuracy for different action levels. Process capability tests were also performed on the retrospective data to define tolerances based on user‐specified levels. A second study was carried out whereby physical couch offsets were applied using the TQA module and the MVCT detector was used to detect the observed variations. Random and systematic variations were observed for the SPC‐based upper and lower control limits, and investigations were carried out to maintain the ongoing stability of the process for a 4‐year and a three‐monthly period. Local trend analysis showed mean variations up to ±0.5 mm in the three‐monthly analysis period for all IEC offset measurements. Variations were also observed in the detected versus applied offsets using the MVCT detector in the second study largely in the vertical direction, and actions were taken to remediate this error. Based on the results, it was recommended that imaging shifts in each coordinate direction be only applied after assessing the machine for applied versus detected test results using the step helical module. User‐specified tolerance levels of at least ±2 mm were recommended for a test frequency of once every 3 months to improve couch positional accuracy. SPC enables detection of systematic variations prior to reaching machine tolerance levels. Couch encoding system recalibrations reduced variations to user‐specified levels and a monitoring period of 3 months using SPC facilitated in detecting systematic and random variations. SPC analysis for couch positional accuracy enabled greater control in the identification of errors, thereby increasing confidence levels in daily treatment setups. John Wiley and Sons Inc. 2017-07-21 /pmc/articles/PMC5874965/ /pubmed/28730740 http://dx.doi.org/10.1002/acm2.12136 Text en © 2017 Royal Brisbane and Women's Hospital, Metro North Hospital and Health Service. Journal of Applied Clinical Medical Physics published by Wiley Periodicals, Inc. on behalf of American Association of Physicists in Medicine. This is an open access article under the terms of the http://creativecommons.org/licenses/by/4.0/ License, which permits use, distribution and reproduction in any medium, provided the original work is properly cited. |
spellingShingle | Radiation Oncology Physics Binny, Diana Lancaster, Craig M. Trapp, Jamie V. Crowe, Scott B. Statistical process control and verifying positional accuracy of a cobra motion couch using step‐wedge quality assurance tool |
title | Statistical process control and verifying positional accuracy of a cobra motion couch using step‐wedge quality assurance tool |
title_full | Statistical process control and verifying positional accuracy of a cobra motion couch using step‐wedge quality assurance tool |
title_fullStr | Statistical process control and verifying positional accuracy of a cobra motion couch using step‐wedge quality assurance tool |
title_full_unstemmed | Statistical process control and verifying positional accuracy of a cobra motion couch using step‐wedge quality assurance tool |
title_short | Statistical process control and verifying positional accuracy of a cobra motion couch using step‐wedge quality assurance tool |
title_sort | statistical process control and verifying positional accuracy of a cobra motion couch using step‐wedge quality assurance tool |
topic | Radiation Oncology Physics |
url | https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5874965/ https://www.ncbi.nlm.nih.gov/pubmed/28730740 http://dx.doi.org/10.1002/acm2.12136 |
work_keys_str_mv | AT binnydiana statisticalprocesscontrolandverifyingpositionalaccuracyofacobramotioncouchusingstepwedgequalityassurancetool AT lancastercraigm statisticalprocesscontrolandverifyingpositionalaccuracyofacobramotioncouchusingstepwedgequalityassurancetool AT trappjamiev statisticalprocesscontrolandverifyingpositionalaccuracyofacobramotioncouchusingstepwedgequalityassurancetool AT crowescottb statisticalprocesscontrolandverifyingpositionalaccuracyofacobramotioncouchusingstepwedgequalityassurancetool |