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Evaluation of target motion and determination optional treatment margins for prostate cancer treated with external beam radiotherapy on Halcyon
Background External beam radiotherapy (EBRT) is an important part of the treatment for prostate cancer. To account for organ motion and set-up error, margins are used in radiotherapy planning. These are essential for the delivery of safe and effective treatment. Aim and Setting To measure prostate m...
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| Format: | Thesis |
| Language: | English |
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Division of Radiology
2024
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| _version_ | 1867613243015430144 |
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| access_status_str | Open Access |
| author | Algar, Marion |
| author2 | Punt, Lydia |
| author_browse | Algar, Marion Punt, Lydia |
| author_facet | Punt, Lydia Algar, Marion |
| author_sort | Algar, Marion |
| collection | Thesis |
| description | Background External beam radiotherapy (EBRT) is an important part of the treatment for prostate cancer. To account for organ motion and set-up error, margins are used in radiotherapy planning. These are essential for the delivery of safe and effective treatment. Aim and Setting To measure prostate motion during the course of EBRT on the HalcyonTM at Groote Schuur Hospital. Using published margin recipes, the minimum clinical target volume (CTV)-planning target volume (PTV) expansion margin was calculated. Patients and Methods Prostate motion was evaluated by comparing prostate position on the planning CT to cone-beam CT (CBCT) scans. Prostate position error in the medio-lateral (ML), antero-posterior (AP) and superoinferior (SI) directions was measured for each CBCT. The systematic (Σ) and random (σ) error of prostate motion was calculated. The minimum CTV-PTV margin was determined. Results The mean position error of the prostate was -0.04mm (95% CI -0.14, 0.10), -0.30mm (95% CI -0.70, 0.15) and -0.40mm (95% CI -0.89, 0.00) in the ML, AP and SI directions, respectively. Using Van Herk's margin formula (2.5Σ +0.7σ), the following minimum CTV-PTV margins for the ML, AP and SI directions were calculated: 1.9mm, 6.9mm and 7.8mm, respectively. Using Stroom's margin formula (2Σ +0.7σ), the following minimum CTV-PTV margins for the ML, AP and SI directions were calculated: 1.6mm, 5.8mm and 6.6mm, respectively. Conclusion Based on prostate motion, our institution's current margins are sufficient. However, further studies are necessary to measure other factors that influence the CTV-PTV margin before considering reducing this margin. |
| format | Thesis |
| id | oai:open.uct.ac.za:11427/39261 |
| institution | University of Cape Town (South Africa) |
| language | eng |
| last_indexed | 2026-06-10T12:33:01.081Z |
| license_str | Not specified — see source repository |
| provenance_str_mv | Harvested via OAI-PMH from UCTD — University of Cape Town Open Access Repository |
| publishDate | 2024 |
| publishDateRange | 2024 |
| publishDateSort | 2024 |
| publisher | Division of Radiology |
| publisherStr | Division of Radiology |
| record_format | dspace |
| source_str | UCTD — University of Cape Town Open Access Repository |
| spelling | oai:open.uct.ac.za:11427/39261 Evaluation of target motion and determination optional treatment margins for prostate cancer treated with external beam radiotherapy on Halcyon Algar, Marion Punt, Lydia Radiation Oncology Background External beam radiotherapy (EBRT) is an important part of the treatment for prostate cancer. To account for organ motion and set-up error, margins are used in radiotherapy planning. These are essential for the delivery of safe and effective treatment. Aim and Setting To measure prostate motion during the course of EBRT on the HalcyonTM at Groote Schuur Hospital. Using published margin recipes, the minimum clinical target volume (CTV)-planning target volume (PTV) expansion margin was calculated. Patients and Methods Prostate motion was evaluated by comparing prostate position on the planning CT to cone-beam CT (CBCT) scans. Prostate position error in the medio-lateral (ML), antero-posterior (AP) and superoinferior (SI) directions was measured for each CBCT. The systematic (Σ) and random (σ) error of prostate motion was calculated. The minimum CTV-PTV margin was determined. Results The mean position error of the prostate was -0.04mm (95% CI -0.14, 0.10), -0.30mm (95% CI -0.70, 0.15) and -0.40mm (95% CI -0.89, 0.00) in the ML, AP and SI directions, respectively. Using Van Herk's margin formula (2.5Σ +0.7σ), the following minimum CTV-PTV margins for the ML, AP and SI directions were calculated: 1.9mm, 6.9mm and 7.8mm, respectively. Using Stroom's margin formula (2Σ +0.7σ), the following minimum CTV-PTV margins for the ML, AP and SI directions were calculated: 1.6mm, 5.8mm and 6.6mm, respectively. Conclusion Based on prostate motion, our institution's current margins are sufficient. However, further studies are necessary to measure other factors that influence the CTV-PTV margin before considering reducing this margin. 2024-03-28T09:31:11Z 2024-03-28T09:31:11Z 2023 2024-03-28T08:28:58Z Thesis / Dissertation Masters MMed http://hdl.handle.net/11427/39261 eng application/pdf Division of Radiology Faculty of Health Sciences |
| spellingShingle | Radiation Oncology Algar, Marion Evaluation of target motion and determination optional treatment margins for prostate cancer treated with external beam radiotherapy on Halcyon |
| thesis_degree_str | Master's |
| title | Evaluation of target motion and determination optional treatment margins for prostate cancer treated with external beam radiotherapy on Halcyon |
| title_full | Evaluation of target motion and determination optional treatment margins for prostate cancer treated with external beam radiotherapy on Halcyon |
| title_fullStr | Evaluation of target motion and determination optional treatment margins for prostate cancer treated with external beam radiotherapy on Halcyon |
| title_full_unstemmed | Evaluation of target motion and determination optional treatment margins for prostate cancer treated with external beam radiotherapy on Halcyon |
| title_short | Evaluation of target motion and determination optional treatment margins for prostate cancer treated with external beam radiotherapy on Halcyon |
| title_sort | evaluation of target motion and determination optional treatment margins for prostate cancer treated with external beam radiotherapy on halcyon |
| topic | Radiation Oncology |
| url | http://hdl.handle.net/11427/39261 |
| work_keys_str_mv | AT algarmarion evaluationoftargetmotionanddeterminationoptionaltreatmentmarginsforprostatecancertreatedwithexternalbeamradiotherapyonhalcyon |