{"id":{"repo_id":"creighton","oai_identifier":"oai:cdr.creighton.edu:10504/136773"},"canonical_url":"https://search.dev.ndltd.org/etd/creighton/oai:cdr.creighton.edu:10504/136773","repository":{"repo_id":"creighton","name":"Creighton University","base_url":"https://cdr.creighton.edu/server/oai/request"},"display":{"title":"Towards Offline Adaptive Therapy for Prostate Patients using Velocity","abstract":"The goal of this project is to assess the feasibility of three offline adaptive workflows for prostate radiotherapy (RT) through a retrospective study, potentially allowing future offline dose assessment and adaptive replanning for prostate bed RT. We investigated an offline adaptive therapy workflow previously developed for head-and-neck patients on a small cohort of seven prostate patients over their first five fractions. Because this workflow was previously shown to have poor deformations in the pelvis, a lower-bound threshold contour was used to reduce bladder-volume variation. Three workflow variations were assessed for accuracy in estimated bladder volume and delivered dose-to-bladder: Velocity’s “Navigator” using full region-of-interest (fROI), Navigator with a reduced ROI (rROI), and structure-guided deformation (SGD). DICE similarity coefficients (DSC) were compared between deformed bladder volumes and true day-of-treatment volumes. Workflow-estimated dose-to-bladder and NTCP were compared to ground-truth calculations. The average ratio of day-of-treatment bladder volume compared to simulation was 82±17% for 6 of the 7 patients. For these patients, the fROI and rROI workflows tended to over-estimate bladder volume, with average DSCs of 0.786±0.055 and 0.757±0.069 respectively, whereas the SGD workflow agreed with the true volume (0.902±0.034). Correspondingly, the fROI and rROI workflows tended to underestimate bladder dose (fractional dose differences up to 94%) and normal tissue complication probability (NTCP), with improved agreement using SGD. The first patient’s bladder tended to be extremely over-filled, with day-of-treatment volume up to 548% simulation volume. Due to the large volume difference, poor deformations resulted in unreliable day-of-treatment bladder volume, dose, and NTCP estimates for all workflows. The SGD workflow with a lower-bound threshold for bladder fill at treatment is feasible for offline bladder-dose assessment for prostate treatments and may enable future adaptive replanning. All workflows were inaccurate for drastically over-filled bladder volumes, but since over-filling does not tend to result in increased bladder dose/NTCP, it is not of great concern for offline dose assessment. Recommendations for clinical use were derived from our findings.","abstract_html":"The goal of this project is to assess the feasibility of three offline adaptive workflows for prostate radiotherapy (RT) through a retrospective study, potentially allowing future offline dose assessment and adaptive replanning for prostate bed RT. We investigated an offline adaptive therapy workflow previously developed for head-and-neck patients on a small cohort of seven prostate patients over their first five fractions. Because this workflow was previously shown to have poor deformations in the pelvis, a lower-bound threshold contour was used to reduce bladder-volume variation. Three workflow variations were assessed for accuracy in estimated bladder volume and delivered dose-to-bladder: Velocity’s “Navigator” using full region-of-interest (fROI), Navigator with a reduced ROI (rROI), and structure-guided deformation (SGD). DICE similarity coefficients (DSC) were compared between deformed bladder volumes and true day-of-treatment volumes. Workflow-estimated dose-to-bladder and NTCP were compared to ground-truth calculations. The average ratio of day-of-treatment bladder volume compared to simulation was 82±17% for 6 of the 7 patients. For these patients, the fROI and rROI workflows tended to over-estimate bladder volume, with average DSCs of 0.786±0.055 and 0.757±0.069 respectively, whereas the SGD workflow agreed with the true volume (0.902±0.034). Correspondingly, the fROI and rROI workflows tended to underestimate bladder dose (fractional dose differences up to 94%) and normal tissue complication probability (NTCP), with improved agreement using SGD. The first patient’s bladder tended to be extremely over-filled, with day-of-treatment volume up to 548% simulation volume. Due to the large volume difference, poor deformations resulted in unreliable day-of-treatment bladder volume, dose, and NTCP estimates for all workflows. The SGD workflow with a lower-bound threshold for bladder fill at treatment is feasible for offline bladder-dose assessment for prostate treatments and may enable future adaptive replanning. All workflows were inaccurate for drastically over-filled bladder volumes, but since over-filling does not tend to result in increased bladder dose/NTCP, it is not of great concern for offline dose assessment. Recommendations for clinical use were derived from our findings.","abstract_has_math":false,"creators":["Bacon, Elizabeth"],"institution":"Creighton University","degree_name":null,"degree_level":null,"degree_discipline":null,"degree_department":null,"school":null,"contributors":[],"advisors":["Hyun, Megan A."],"committee_chairs":[],"committee_members":[],"year":2022,"date_issued":"2022-04-29","date_published":"2022-04-29","updated_at":"2026-07-24T01:50:13Z","subjects":[],"languages":["en_US"],"rights":["Copyright is retained by the Author. A non-exclusive distribution right is granted to Creighton University and to ProQuest following the publishing model selected above."],"rights_urls":[],"identifier_entries":[]},"links":{"outbound_url":"http://hdl.handle.net/10504/136773","outbound_label":"Handle","outbound_source":"dc:identifier.uri"},"metadata_groups":[{"id":"people","label":"People","entries":[{"key":"dc:contributor.advisor","label":"Advisor","values":["Hyun, Megan A."]},{"key":"dc:creator","label":"Author","values":["Bacon, Elizabeth"]}]},{"id":"academic_context","label":"Academic Context","entries":[{"key":"dc:date.accessioned","label":"Dc Date Accessioned","values":["2022-05-11T14:39:20Z"]},{"key":"dc:date.available","label":"Dc Date Available","values":["2022-05-11T14:39:20Z"]},{"key":"dc:date.issued","label":"Date","values":["2022-04-29"]},{"key":"dc:publisher","label":"Institution","values":["Creighton University"]},{"key":"dc:type","label":"Dc Type","values":["Dissertation"]}]},{"id":"language_rights","label":"Language and Rights","entries":[{"key":"dc:language.iso","label":"Language (ISO)","values":["en_US"]},{"key":"dc:rights","label":"Dc Rights","values":["Copyright is retained by the Author. A non-exclusive distribution right is granted to Creighton University and to ProQuest following the publishing model selected above."]}]},{"id":"identifiers","label":"Identifiers","entries":[{"key":"dc:identifier.uri","label":"Identifier URI","values":["http://hdl.handle.net/10504/136773"]}]},{"id":"additional","label":"Additional Metadata","entries":[{"key":"dc:description.abstract","label":"Abstract","values":["The goal of this project is to assess the feasibility of three offline adaptive workflows for prostate radiotherapy (RT) through a retrospective study, potentially allowing future offline dose assessment and adaptive replanning for prostate bed RT. We investigated an offline adaptive therapy workflow previously developed for head-and-neck patients on a small cohort of seven prostate patients over their first five fractions. Because this workflow was previously shown to have poor deformations in the pelvis, a lower-bound threshold contour was used to reduce bladder-volume variation. Three workflow variations were assessed for accuracy in estimated bladder volume and delivered dose-to-bladder: Velocity’s “Navigator” using full region-of-interest (fROI), Navigator with a reduced ROI (rROI), and structure-guided deformation (SGD). DICE similarity coefficients (DSC) were compared between deformed bladder volumes and true day-of-treatment volumes. Workflow-estimated dose-to-bladder and NTCP were compared to ground-truth calculations. The average ratio of day-of-treatment bladder volume compared to simulation was 82±17% for 6 of the 7 patients. For these patients, the fROI and rROI workflows tended to over-estimate bladder volume, with average DSCs of 0.786±0.055 and 0.757±0.069 respectively, whereas the SGD workflow agreed with the true volume (0.902±0.034). Correspondingly, the fROI and rROI workflows tended to underestimate bladder dose (fractional dose differences up to 94%) and normal tissue complication probability (NTCP), with improved agreement using SGD. The first patient’s bladder tended to be extremely over-filled, with day-of-treatment volume up to 548% simulation volume. Due to the large volume difference, poor deformations resulted in unreliable day-of-treatment bladder volume, dose, and NTCP estimates for all workflows. The SGD workflow with a lower-bound threshold for bladder fill at treatment is feasible for offline bladder-dose assessment for prostate treatments and may enable future adaptive replanning. All workflows were inaccurate for drastically over-filled bladder volumes, but since over-filling does not tend to result in increased bladder dose/NTCP, it is not of great concern for offline dose assessment. Recommendations for clinical use were derived from our findings."]},{"key":"dc:title","label":"Title","values":["Towards Offline Adaptive Therapy for Prostate Patients using Velocity"]}]}],"canonical_facts":{"dc:contributor.advisor":["Hyun, Megan A."],"dc:creator":["Bacon, Elizabeth"],"dc:date.accessioned":["2022-05-11T14:39:20Z"],"dc:date.available":["2022-05-11T14:39:20Z"],"dc:date.issued":["2022-04-29"],"dc:description.abstract":["The goal of this project is to assess the feasibility of three offline adaptive workflows for prostate radiotherapy (RT) through a retrospective study, potentially allowing future offline dose assessment and adaptive replanning for prostate bed RT. We investigated an offline adaptive therapy workflow previously developed for head-and-neck patients on a small cohort of seven prostate patients over their first five fractions. Because this workflow was previously shown to have poor deformations in the pelvis, a lower-bound threshold contour was used to reduce bladder-volume variation. Three workflow variations were assessed for accuracy in estimated bladder volume and delivered dose-to-bladder: Velocity’s “Navigator” using full region-of-interest (fROI), Navigator with a reduced ROI (rROI), and structure-guided deformation (SGD). DICE similarity coefficients (DSC) were compared between deformed bladder volumes and true day-of-treatment volumes. Workflow-estimated dose-to-bladder and NTCP were compared to ground-truth calculations. The average ratio of day-of-treatment bladder volume compared to simulation was 82±17% for 6 of the 7 patients. For these patients, the fROI and rROI workflows tended to over-estimate bladder volume, with average DSCs of 0.786±0.055 and 0.757±0.069 respectively, whereas the SGD workflow agreed with the true volume (0.902±0.034). Correspondingly, the fROI and rROI workflows tended to underestimate bladder dose (fractional dose differences up to 94%) and normal tissue complication probability (NTCP), with improved agreement using SGD. The first patient’s bladder tended to be extremely over-filled, with day-of-treatment volume up to 548% simulation volume. Due to the large volume difference, poor deformations resulted in unreliable day-of-treatment bladder volume, dose, and NTCP estimates for all workflows. The SGD workflow with a lower-bound threshold for bladder fill at treatment is feasible for offline bladder-dose assessment for prostate treatments and may enable future adaptive replanning. All workflows were inaccurate for drastically over-filled bladder volumes, but since over-filling does not tend to result in increased bladder dose/NTCP, it is not of great concern for offline dose assessment. Recommendations for clinical use were derived from our findings."],"dc:identifier.uri":["http://hdl.handle.net/10504/136773"],"dc:language.iso":["en_US"],"dc:publisher":["Creighton University"],"dc:rights":["Copyright is retained by the Author. A non-exclusive distribution right is granted to Creighton University and to ProQuest following the publishing model selected above."],"dc:title":["Towards Offline Adaptive Therapy for Prostate Patients using Velocity"],"dc:type":["Dissertation"]},"updated_at":"2026-07-24T01:50:13Z"}