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Pulse-Resolved Dosimetry Using CVD Diamond Detectors and Applications in Advanced Radiotherapy Treatment / MOHD HANIFA

Swansea University Author: MOHD HANIFA

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DOI (Published version): 10.23889/SUThesis.71896

Abstract

A pulse-by-pulse dosimetry system based on diamond material was developed for the purpose of point dose measurements that require high spatial and temporal dose resolutions during VMAT technique delivery. In collaboration with the University of Bristol, a front-end electrometer with a high sample-ra...

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Published: Swansea 2021
Institution: Swansea University
Degree level: Doctoral
Degree name: Ph.D
Supervisor: Hugtenburg, R. P., and Al-Affan, I.
URI: https://cronfa.swan.ac.uk/Record/cronfa71896
first_indexed 2026-05-14T12:08:34Z
last_indexed 2026-05-15T05:41:58Z
id cronfa71896
recordtype RisThesis
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In collaboration with the University of Bristol, a front-end electrometer with a high sample-rate was developed to measure individual pulses generated from the therapeutic linear accelerator (LINAC).One of the main drawbacks of using diamond detectors in the dosimetry field is the non-linear characteristic of the diamond response against the radiation dose-rate (&#x2206;). The dose-rate dependency of several diamond detectors was investigated, including the commercial diamond detector known as microDiamond and a purchased prototype diamond detector known as DD4. Two methods were employed in varying the dose-rate, either by varying the pulse-rate of the LINAC or varying the distance between the radiation source and the detector. The &#x2206; values obtained for the microDiamond detector were 0.9985 &#xB1; 0.0005 and 0.9870 &#xB1; 0.0024 based on the first and second method, respectively. For the DD4 detector, the &#x2206; value obtained based on the second method was 0.996 &#xB1; 0.025, which was close to the value of 0.99 &#xB1; 0.03 reported in previous work for DD4.The dosimetry system based on LINAC has successfully measured the dose for each pulse up to the rate of 400 Hz. The signal response from the DD4 detector was analysed and the models of the dose deposited were reconstructed based on the data obtained from the treatment planning system (TPS) and the LINAC logfile. Both models indicate dose differences of less than 0.5 % compared to the measurement.Cumulative dose as a function of time and gantry angle-to-agreement (&#x2206;t/&#x2206;g) were evaluated using a gamma-like analysis to determine the percentage of gamma passing rates (%GP). The %GP for cumulative dose evaluation against the time of 5%/1s was 100 % for both TPS and LINAC logfile compared to the measurement, and above 95 % with 3 %/1s criterion for both evaluated parameters. The %GP for cumulative dose evaluation against the gantry angle with 5 %/40 and 3 %/40 achieved above 95 %for both comparisons. The evaluation was also conducted for the instantaneous dose but with a high failure in %GP.With improvements in the front-end and using a newly installed Elekta Agility,a treatment plan was created for an anonymised prostate cancer patient using VMAT technique delivery in a phantom. The signal response from the DD4 detector was analysed using a more sophisticated method where the signal response was separated from the background (BG) signal for individual pulses. The result of the investigation shows the change in BG as a function of the pulse repetition frequency (PRF). The analysis also revealed that the average dose per pulse increases at higher PRF. A comparison of the cumulative dose measured by the DD4 detector and the commercial independent dose calculation tool known as RadCalc reveals the dose per control point (CP). 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spelling 2026-05-14T13:32:16.3042392 v2 71896 2026-05-14 Pulse-Resolved Dosimetry Using CVD Diamond Detectors and Applications in Advanced Radiotherapy Treatment d47d70acf0a9482dc2af5a33dc0de3a8 MOHD HANIFA MOHD HANIFA true false 2026-05-14 A pulse-by-pulse dosimetry system based on diamond material was developed for the purpose of point dose measurements that require high spatial and temporal dose resolutions during VMAT technique delivery. In collaboration with the University of Bristol, a front-end electrometer with a high sample-rate was developed to measure individual pulses generated from the therapeutic linear accelerator (LINAC).One of the main drawbacks of using diamond detectors in the dosimetry field is the non-linear characteristic of the diamond response against the radiation dose-rate (∆). The dose-rate dependency of several diamond detectors was investigated, including the commercial diamond detector known as microDiamond and a purchased prototype diamond detector known as DD4. Two methods were employed in varying the dose-rate, either by varying the pulse-rate of the LINAC or varying the distance between the radiation source and the detector. The ∆ values obtained for the microDiamond detector were 0.9985 ± 0.0005 and 0.9870 ± 0.0024 based on the first and second method, respectively. For the DD4 detector, the ∆ value obtained based on the second method was 0.996 ± 0.025, which was close to the value of 0.99 ± 0.03 reported in previous work for DD4.The dosimetry system based on LINAC has successfully measured the dose for each pulse up to the rate of 400 Hz. The signal response from the DD4 detector was analysed and the models of the dose deposited were reconstructed based on the data obtained from the treatment planning system (TPS) and the LINAC logfile. Both models indicate dose differences of less than 0.5 % compared to the measurement.Cumulative dose as a function of time and gantry angle-to-agreement (∆t/∆g) were evaluated using a gamma-like analysis to determine the percentage of gamma passing rates (%GP). The %GP for cumulative dose evaluation against the time of 5%/1s was 100 % for both TPS and LINAC logfile compared to the measurement, and above 95 % with 3 %/1s criterion for both evaluated parameters. The %GP for cumulative dose evaluation against the gantry angle with 5 %/40 and 3 %/40 achieved above 95 %for both comparisons. The evaluation was also conducted for the instantaneous dose but with a high failure in %GP.With improvements in the front-end and using a newly installed Elekta Agility,a treatment plan was created for an anonymised prostate cancer patient using VMAT technique delivery in a phantom. The signal response from the DD4 detector was analysed using a more sophisticated method where the signal response was separated from the background (BG) signal for individual pulses. The result of the investigation shows the change in BG as a function of the pulse repetition frequency (PRF). The analysis also revealed that the average dose per pulse increases at higher PRF. A comparison of the cumulative dose measured by the DD4 detector and the commercial independent dose calculation tool known as RadCalc reveals the dose per control point (CP). Gamma-like analysis showed that there was an excellent agreement between the measured and intended cumulative dose delivered with %GP, was 100 % for a 1 %/2s criterion. E-Thesis Swansea radiotherapy dosimetry, diamond detectors 19 3 2021 2021-03-19 10.23889/SUThesis.71896 COLLEGE NANME COLLEGE CODE Swansea University Hugtenburg, R. P., and Al-Affan, I. Doctoral Ph.D Malaysian Government Malaysian Government 2026-05-14T13:32:16.3042392 2026-05-14T12:59:39.4143615 Faculty of Medicine, Health and Life Sciences Swansea University Medical School - Medicine MOHD HANIFA 1 71896__36728__fe433f69c6b54b3f8addae73a8d95534.pdf 2020_Hanifa_A.final.71896.pdf 2026-05-14T13:07:13.4505880 Output 4967459 application/pdf E-Thesis – open access true Copyright: the author, Mohd Ariff Mohamed Hanifa, 2026. Distributed under the terms of a Creative Commons Attribution-NoDerivatives 4.0 License (CC BY-NC 4.0). true eng https://creativecommons.org/licenses/by-nc/4.0/
title Pulse-Resolved Dosimetry Using CVD Diamond Detectors and Applications in Advanced Radiotherapy Treatment
spellingShingle Pulse-Resolved Dosimetry Using CVD Diamond Detectors and Applications in Advanced Radiotherapy Treatment
MOHD HANIFA
title_short Pulse-Resolved Dosimetry Using CVD Diamond Detectors and Applications in Advanced Radiotherapy Treatment
title_full Pulse-Resolved Dosimetry Using CVD Diamond Detectors and Applications in Advanced Radiotherapy Treatment
title_fullStr Pulse-Resolved Dosimetry Using CVD Diamond Detectors and Applications in Advanced Radiotherapy Treatment
title_full_unstemmed Pulse-Resolved Dosimetry Using CVD Diamond Detectors and Applications in Advanced Radiotherapy Treatment
title_sort Pulse-Resolved Dosimetry Using CVD Diamond Detectors and Applications in Advanced Radiotherapy Treatment
author_id_str_mv d47d70acf0a9482dc2af5a33dc0de3a8
author_id_fullname_str_mv d47d70acf0a9482dc2af5a33dc0de3a8_***_MOHD HANIFA
author MOHD HANIFA
author2 MOHD HANIFA
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publishDate 2021
institution Swansea University
doi_str_mv 10.23889/SUThesis.71896
college_str Faculty of Medicine, Health and Life Sciences
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hierarchy_top_id facultyofmedicinehealthandlifesciences
hierarchy_top_title Faculty of Medicine, Health and Life Sciences
hierarchy_parent_id facultyofmedicinehealthandlifesciences
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 pulse-by-pulse dosimetry system based on diamond material was developed for the purpose of point dose measurements that require high spatial and temporal dose resolutions during VMAT technique delivery. In collaboration with the University of Bristol, a front-end electrometer with a high sample-rate was developed to measure individual pulses generated from the therapeutic linear accelerator (LINAC).One of the main drawbacks of using diamond detectors in the dosimetry field is the non-linear characteristic of the diamond response against the radiation dose-rate (∆). The dose-rate dependency of several diamond detectors was investigated, including the commercial diamond detector known as microDiamond and a purchased prototype diamond detector known as DD4. Two methods were employed in varying the dose-rate, either by varying the pulse-rate of the LINAC or varying the distance between the radiation source and the detector. The ∆ values obtained for the microDiamond detector were 0.9985 ± 0.0005 and 0.9870 ± 0.0024 based on the first and second method, respectively. For the DD4 detector, the ∆ value obtained based on the second method was 0.996 ± 0.025, which was close to the value of 0.99 ± 0.03 reported in previous work for DD4.The dosimetry system based on LINAC has successfully measured the dose for each pulse up to the rate of 400 Hz. The signal response from the DD4 detector was analysed and the models of the dose deposited were reconstructed based on the data obtained from the treatment planning system (TPS) and the LINAC logfile. Both models indicate dose differences of less than 0.5 % compared to the measurement.Cumulative dose as a function of time and gantry angle-to-agreement (∆t/∆g) were evaluated using a gamma-like analysis to determine the percentage of gamma passing rates (%GP). The %GP for cumulative dose evaluation against the time of 5%/1s was 100 % for both TPS and LINAC logfile compared to the measurement, and above 95 % with 3 %/1s criterion for both evaluated parameters. The %GP for cumulative dose evaluation against the gantry angle with 5 %/40 and 3 %/40 achieved above 95 %for both comparisons. The evaluation was also conducted for the instantaneous dose but with a high failure in %GP.With improvements in the front-end and using a newly installed Elekta Agility,a treatment plan was created for an anonymised prostate cancer patient using VMAT technique delivery in a phantom. The signal response from the DD4 detector was analysed using a more sophisticated method where the signal response was separated from the background (BG) signal for individual pulses. The result of the investigation shows the change in BG as a function of the pulse repetition frequency (PRF). The analysis also revealed that the average dose per pulse increases at higher PRF. A comparison of the cumulative dose measured by the DD4 detector and the commercial independent dose calculation tool known as RadCalc reveals the dose per control point (CP). Gamma-like analysis showed that there was an excellent agreement between the measured and intended cumulative dose delivered with %GP, was 100 % for a 1 %/2s criterion.
published_date 2021-03-19T06:41:58Z
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score 11.105796

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