Complex field verification using a large area CMOS MAPS upstream in radiotherapy

Pritchard, J.L.; Velthuis, J.J.; Beck, L.; Li, Y.; Sio, C. De; Ballisat, L.; Duan, J.; Shi, Y.; Hugtenburg, Richard

doi:10.1088/1748-0221/17/08/c08018

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Complex field verification using a large area CMOS MAPS upstream in radiotherapy

J.L. Pritchard, J.J. Velthuis, L. Beck, Y. Li, C. De Sio, L. Ballisat, J. Duan, Y. Shi, Richard Hugtenburg

Journal of Instrumentation, Volume: 17, Issue: 08, Start page: C08018

Swansea University Author: Richard Hugtenburg

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DOI (Published version): 10.1088/1748-0221/17/08/c08018

Abstract

A multileaf collimator (MLC) is an integral component in modern radiotherapy machines as it dynamically shapes the photon field used for patient treatment. Currently, the MLC leaves which collimate the treatment field are mechanically calibrated to ±1 mm every 3 months and during pre-treatment calib...

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Published in:	Journal of Instrumentation
ISSN:	1748-0221
Published:	IOP Publishing 2022
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URI:	https://cronfa.swan.ac.uk/Record/cronfa62050
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Leaf drift can occur between calibration dates and hence exceed the ±1 mm tolerance. Pre-treatment verification, increases LINAC usage time so is seldom performed for each individual patient treatment, but instead for an acceptable sample of patients and/or treatment fractions. Independent real-time treatment verification is therefore desirable. We are developing a large area CMOS MAPS upstream of the patient to monitor MLC leaf positions for real-time treatment verification. CMOS MAPS are radiation hard for photon and electron irradiation, have high readout speeds and low attenuation which makes them an ideal upstream radiation detector for radiotherapy. Previously, we reported on leaf position reconstruction for single leaves using the Lassena, a 12 × 14 cm2, three side buttable MAPS suitable for clinical deployment. Sobel operator based methods were used for edge reconstruction. It was shown that the correspondence between reconstructed and set leaf position was excellent and resolutions ranged between 60.6 ± 8 and 109 ± 12 μm for a single central leaf with leaf extensions ranging from 1 to 35 mm using 0.3 sec of treatment beam time at 400 MU/min. Here, we report on leaf edge reconstruction using updated methods for complex leaf configurations, as occur in clinical use. Results show that leaf positions can be reconstructed with resolutions of 62 ± 6 μm for single leaves and 86 ± 16 μm for adjacent leaves at the isocenter using 0.15 sec at 400 MU/min of treatment beam. 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spelling	2022-12-12T13:48:54.5272075 v2 62050 2022-11-25 Complex field verification using a large area CMOS MAPS upstream in radiotherapy efd2f52ea19cb047e01a01e6fa6fa54c 0000-0003-0352-9607 Richard Hugtenburg Richard Hugtenburg true false 2022-11-25 MEDP A multileaf collimator (MLC) is an integral component in modern radiotherapy machines as it dynamically shapes the photon field used for patient treatment. Currently, the MLC leaves which collimate the treatment field are mechanically calibrated to ±1 mm every 3 months and during pre-treatment calibration are calibrated to the mechanically set leaf positions. Leaf drift can occur between calibration dates and hence exceed the ±1 mm tolerance. Pre-treatment verification, increases LINAC usage time so is seldom performed for each individual patient treatment, but instead for an acceptable sample of patients and/or treatment fractions. Independent real-time treatment verification is therefore desirable. We are developing a large area CMOS MAPS upstream of the patient to monitor MLC leaf positions for real-time treatment verification. CMOS MAPS are radiation hard for photon and electron irradiation, have high readout speeds and low attenuation which makes them an ideal upstream radiation detector for radiotherapy. Previously, we reported on leaf position reconstruction for single leaves using the Lassena, a 12 × 14 cm2, three side buttable MAPS suitable for clinical deployment. Sobel operator based methods were used for edge reconstruction. It was shown that the correspondence between reconstructed and set leaf position was excellent and resolutions ranged between 60.6 ± 8 and 109 ± 12 μm for a single central leaf with leaf extensions ranging from 1 to 35 mm using 0.3 sec of treatment beam time at 400 MU/min. Here, we report on leaf edge reconstruction using updated methods for complex leaf configurations, as occur in clinical use. Results show that leaf positions can be reconstructed with resolutions of 62 ± 6 μm for single leaves and 86 ± 16 μm for adjacent leaves at the isocenter using 0.15 sec at 400 MU/min of treatment beam. These resolutions are significantly better than current calibration standards. Journal Article Journal of Instrumentation 17 08 C08018 IOP Publishing 1748-0221 Radiotherapy concepts; Solid state detectors; X-ray detectors; Image reconstruction in medical imaging 23 8 2022 2022-08-23 10.1088/1748-0221/17/08/c08018 COLLEGE NANME Medical Physics COLLEGE CODE MEDP Swansea University 2022-12-12T13:48:54.5272075 2022-11-25T17:16:43.4576107 Faculty of Medicine, Health and Life Sciences Swansea University Medical School - Medicine J.L. Pritchard 1 J.J. Velthuis 2 L. Beck 3 Y. Li 4 C. De Sio 5 L. Ballisat 6 J. Duan 7 Y. Shi 8 Richard Hugtenburg 0000-0003-0352-9607 9 62050__26065__b26748c0581f4910b1ff78ac2f8a8c14.pdf 62050.pdf 2022-12-12T13:47:34.1579116 Output 774437 application/pdf Version of Record true Released under the terms of the Creative Commons Attribution 4.0 licence true eng https://creativecommons.org/licenses/by/4.0/
title	Complex field verification using a large area CMOS MAPS upstream in radiotherapy
spellingShingle	Complex field verification using a large area CMOS MAPS upstream in radiotherapy Richard Hugtenburg
title_short	Complex field verification using a large area CMOS MAPS upstream in radiotherapy
title_full	Complex field verification using a large area CMOS MAPS upstream in radiotherapy
title_fullStr	Complex field verification using a large area CMOS MAPS upstream in radiotherapy
title_full_unstemmed	Complex field verification using a large area CMOS MAPS upstream in radiotherapy
title_sort	Complex field verification using a large area CMOS MAPS upstream in radiotherapy
author_id_str_mv	efd2f52ea19cb047e01a01e6fa6fa54c
author_id_fullname_str_mv	efd2f52ea19cb047e01a01e6fa6fa54c_***_Richard Hugtenburg
author	Richard Hugtenburg
author2	J.L. Pritchard J.J. Velthuis L. Beck Y. Li C. De Sio L. Ballisat J. Duan Y. Shi Richard Hugtenburg
format	Journal article
container_title	Journal of Instrumentation
container_volume	17
container_issue	08
container_start_page	C08018
publishDate	2022
institution	Swansea University
issn	1748-0221
doi_str_mv	10.1088/1748-0221/17/08/c08018
publisher	IOP Publishing
college_str	Faculty of Medicine, Health and Life Sciences
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hierarchy_top_title	Faculty of Medicine, Health and Life Sciences
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hierarchy_parent_title	Faculty of Medicine, Health and Life Sciences
department_str	Swansea University Medical School - Medicine{{{_:::_}}}Faculty of Medicine, Health and Life Sciences{{{_:::_}}}Swansea University Medical School - Medicine
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description	A multileaf collimator (MLC) is an integral component in modern radiotherapy machines as it dynamically shapes the photon field used for patient treatment. Currently, the MLC leaves which collimate the treatment field are mechanically calibrated to ±1 mm every 3 months and during pre-treatment calibration are calibrated to the mechanically set leaf positions. Leaf drift can occur between calibration dates and hence exceed the ±1 mm tolerance. Pre-treatment verification, increases LINAC usage time so is seldom performed for each individual patient treatment, but instead for an acceptable sample of patients and/or treatment fractions. Independent real-time treatment verification is therefore desirable. We are developing a large area CMOS MAPS upstream of the patient to monitor MLC leaf positions for real-time treatment verification. CMOS MAPS are radiation hard for photon and electron irradiation, have high readout speeds and low attenuation which makes them an ideal upstream radiation detector for radiotherapy. Previously, we reported on leaf position reconstruction for single leaves using the Lassena, a 12 × 14 cm2, three side buttable MAPS suitable for clinical deployment. Sobel operator based methods were used for edge reconstruction. It was shown that the correspondence between reconstructed and set leaf position was excellent and resolutions ranged between 60.6 ± 8 and 109 ± 12 μm for a single central leaf with leaf extensions ranging from 1 to 35 mm using 0.3 sec of treatment beam time at 400 MU/min. Here, we report on leaf edge reconstruction using updated methods for complex leaf configurations, as occur in clinical use. Results show that leaf positions can be reconstructed with resolutions of 62 ± 6 μm for single leaves and 86 ± 16 μm for adjacent leaves at the isocenter using 0.15 sec at 400 MU/min of treatment beam. These resolutions are significantly better than current calibration standards.
published_date	2022-08-23T04:21:21Z
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score	11.013731

Complex field verification using a large area CMOS MAPS upstream in radiotherapy

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