Analysis of Performance and Failure Modes of the IROC Proton Liver Phantom
Purpose: To analyze trends in institutional performance and failure modes for the Imaging and Radiation Oncology Core’s (IROC’s) proton liver phantom. Materials and Methods: Results of 66 phantom irradiations from 28 institutions between 2015 and 2020 were retrospectively analyzed. Univariate analys...
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| Format: | Article |
| Language: | English |
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Particle Therapy Co-operative Group
2023-07-01
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| Series: | International Journal of Particle Therapy |
| Subjects: | |
| Online Access: | https://theijpt.org/doi/pdf/10.14338/IJPT-22-00043.1 |
| _version_ | 1797660257122516992 |
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| author | Hunter Mehrens, MS Paige Taylor, MS Paola Alvarez, MS Stephen Kry, PhD |
| author_facet | Hunter Mehrens, MS Paige Taylor, MS Paola Alvarez, MS Stephen Kry, PhD |
| author_sort | Hunter Mehrens, MS |
| collection | DOAJ |
| description | Purpose: To analyze trends in institutional performance and failure modes for the Imaging and Radiation Oncology Core’s (IROC’s) proton liver phantom.
Materials and Methods: Results of 66 phantom irradiations from 28 institutions between 2015 and 2020 were retrospectively analyzed. Univariate analysis and random forest models were used to associate irradiation conditions with phantom results. Phantom results included pass/fail classification, average thermoluminescent dosimeter (TLD) ratio of both targets, and percentage of pixels passing gamma of both targets. The following categories were evaluated in terms of how they predicted these outcomes: irradiation year, treatment planning system (TPS), TPS algorithm, treatment machine, number of irradiations, treatment technique, motion management technique, number of isocenters, and superior-inferior extent (in cm) of the 90% TPS isodose line for primary target 1 (PTV1) and primary target 2 (PTV2). In addition, failures were categorized by failure mode.
Results: Average pass rate was approximately 52% and average TLD ratio for both targets had slightly improved. As the treatment field increased to cover the target, the pass rate statistically significantly fell. Lower pass rates were observed for Mevion machines, scattered irradiation techniques, and gating and internal target volume (ITV) motion management techniques. Overall, the accuracy of the random forest modeling of the phantom results was approximately 73% ± 14%. The most important predictor was the superior-inferior extent for both targets and irradiation year. Three failure modes dominated the failures of the phantom: (1) systematic underdosing, (2) poor localization in the superior-inferior direction, and (3) range error. Only 44% of failures have similar failure modes between the 2 targets.
Conclusion: Improvement of the proton liver phantom has been observed; however, the pass rate remains the lowest among all IROC phantoms. Through various analysis techniques, range uncertainty, motion management, and underdosing are the main culprits of failures of the proton liver phantom. Clinically, careful consideration of the influences of liver proton therapy is needed to improve phantom performance and patient outcome. |
| first_indexed | 2024-03-11T18:28:10Z |
| format | Article |
| id | doaj.art-a52527d9ebf149169445b009d24e80a5 |
| institution | Directory Open Access Journal |
| issn | 2331-5180 |
| language | English |
| last_indexed | 2024-03-11T18:28:10Z |
| publishDate | 2023-07-01 |
| publisher | Particle Therapy Co-operative Group |
| record_format | Article |
| series | International Journal of Particle Therapy |
| spelling | doaj.art-a52527d9ebf149169445b009d24e80a52023-10-13T14:07:13ZengParticle Therapy Co-operative GroupInternational Journal of Particle Therapy2331-51802023-07-01101233110.14338/IJPT-22-00043.1i2331-5180-10-1-23Analysis of Performance and Failure Modes of the IROC Proton Liver PhantomHunter Mehrens, MS0Paige Taylor, MS1Paola Alvarez, MS2Stephen Kry, PhD31 IROC Houston Quality Assurance Center, The University of Texas MD Anderson Cancer Center, Houston, TX, USA1 IROC Houston Quality Assurance Center, The University of Texas MD Anderson Cancer Center, Houston, TX, USA1 IROC Houston Quality Assurance Center, The University of Texas MD Anderson Cancer Center, Houston, TX, USA1 IROC Houston Quality Assurance Center, The University of Texas MD Anderson Cancer Center, Houston, TX, USAPurpose: To analyze trends in institutional performance and failure modes for the Imaging and Radiation Oncology Core’s (IROC’s) proton liver phantom. Materials and Methods: Results of 66 phantom irradiations from 28 institutions between 2015 and 2020 were retrospectively analyzed. Univariate analysis and random forest models were used to associate irradiation conditions with phantom results. Phantom results included pass/fail classification, average thermoluminescent dosimeter (TLD) ratio of both targets, and percentage of pixels passing gamma of both targets. The following categories were evaluated in terms of how they predicted these outcomes: irradiation year, treatment planning system (TPS), TPS algorithm, treatment machine, number of irradiations, treatment technique, motion management technique, number of isocenters, and superior-inferior extent (in cm) of the 90% TPS isodose line for primary target 1 (PTV1) and primary target 2 (PTV2). In addition, failures were categorized by failure mode. Results: Average pass rate was approximately 52% and average TLD ratio for both targets had slightly improved. As the treatment field increased to cover the target, the pass rate statistically significantly fell. Lower pass rates were observed for Mevion machines, scattered irradiation techniques, and gating and internal target volume (ITV) motion management techniques. Overall, the accuracy of the random forest modeling of the phantom results was approximately 73% ± 14%. The most important predictor was the superior-inferior extent for both targets and irradiation year. Three failure modes dominated the failures of the phantom: (1) systematic underdosing, (2) poor localization in the superior-inferior direction, and (3) range error. Only 44% of failures have similar failure modes between the 2 targets. Conclusion: Improvement of the proton liver phantom has been observed; however, the pass rate remains the lowest among all IROC phantoms. Through various analysis techniques, range uncertainty, motion management, and underdosing are the main culprits of failures of the proton liver phantom. Clinically, careful consideration of the influences of liver proton therapy is needed to improve phantom performance and patient outcome.https://theijpt.org/doi/pdf/10.14338/IJPT-22-00043.1liverphantomsquality assuranceiroc |
| spellingShingle | Hunter Mehrens, MS Paige Taylor, MS Paola Alvarez, MS Stephen Kry, PhD Analysis of Performance and Failure Modes of the IROC Proton Liver Phantom International Journal of Particle Therapy liver phantoms quality assurance iroc |
| title | Analysis of Performance and Failure Modes of the IROC Proton Liver Phantom |
| title_full | Analysis of Performance and Failure Modes of the IROC Proton Liver Phantom |
| title_fullStr | Analysis of Performance and Failure Modes of the IROC Proton Liver Phantom |
| title_full_unstemmed | Analysis of Performance and Failure Modes of the IROC Proton Liver Phantom |
| title_short | Analysis of Performance and Failure Modes of the IROC Proton Liver Phantom |
| title_sort | analysis of performance and failure modes of the iroc proton liver phantom |
| topic | liver phantoms quality assurance iroc |
| url | https://theijpt.org/doi/pdf/10.14338/IJPT-22-00043.1 |
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