Developing and validating a simple urethra surrogate model to facilitate dosimetric analysis to predict genitourinary toxicity
Purpose: The urethra is a critical structure in prostate radiotherapy planning; however, it is impossible to visualise on CT. We developed a surrogate urethra model (SUM) for CT-only planning workflow and tested its geometric and dosimetric performance against the MRI-delineated urethra (MDU). Metho...
| Main Authors: | , , , , , , , , |
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| Format: | Article |
| Language: | English |
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Elsevier
2024-05-01
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| Series: | Clinical and Translational Radiation Oncology |
| Subjects: | |
| Online Access: | http://www.sciencedirect.com/science/article/pii/S2405630824000466 |
| _version_ | 1797234316978159616 |
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| author | Ragu Ratnakumaran Jonathan Mohajer Samuel J. Withey Douglas H. Brand Ernest Lee Andrew Loblaw Shaun Tolan Nicholas van As Alison C. Tree |
| author_facet | Ragu Ratnakumaran Jonathan Mohajer Samuel J. Withey Douglas H. Brand Ernest Lee Andrew Loblaw Shaun Tolan Nicholas van As Alison C. Tree |
| author_sort | Ragu Ratnakumaran |
| collection | DOAJ |
| description | Purpose: The urethra is a critical structure in prostate radiotherapy planning; however, it is impossible to visualise on CT. We developed a surrogate urethra model (SUM) for CT-only planning workflow and tested its geometric and dosimetric performance against the MRI-delineated urethra (MDU). Methods: The SUM was compared against 34 different MDUs (within the treatment PTV) in patients treated with 36.25Gy (PTV)/40Gy (CTV) in 5 fractions as part of the PACE-B trial. To assess the surrogate's geometric performance, the Dice similarity coefficient (DSC), Hausdorff distance (HD), mean distance to agreement (MDTA) and the percentage of MDU outside the surrogate (UOS) were calculated. To evaluate the dosimetric performance, a paired t-test was used to calculate the mean of differences between the MDU and SUM for the D99, D98, D50, D2 and D1. The D(n) is the dose (Gy) to n% of the urethra. Results: The median results showed low agreement on DSC (0.32; IQR 0.21–0.41), but low distance to agreement, as would be expected for a small structure (HD 8.4mm (IQR 7.1–10.1mm), MDTA 2.4mm (IQR, 2.2mm-3.2mm)). The UOS was 30% (IQR, 18–54%), indicating nearly a third of the urethra lay outside of the surrogate. However, when comparing urethral dose between the MDU and SUM, the mean of differences for D99, D98 and D95 were 0.12Gy (p=0.57), 0.09Gy (p=0.61), and 0.11Gy (p=0.46) respectively. The mean of differences between the D50, D2 and D1 were 0.08Gy (p=0.04), 0.09Gy (p=0.02) and 0.1Gy (p=0.01) respectively, indicating good dosimetric agreement between MDU and SUM. Conclusion: While there were geometric differences between the MDU and SUM, there was no clinically significant difference between urethral dose-volume parameters. This surrogate model could be validated in a larger cohort and then used to estimate the urethral dose on CT planning scans in those without an MRI planning scan or urinary catheter. |
| first_indexed | 2024-04-24T16:30:08Z |
| format | Article |
| id | doaj.art-1f15466172dd46e9898d15d49ac2dfb3 |
| institution | Directory Open Access Journal |
| issn | 2405-6308 |
| language | English |
| last_indexed | 2024-04-24T16:30:08Z |
| publishDate | 2024-05-01 |
| publisher | Elsevier |
| record_format | Article |
| series | Clinical and Translational Radiation Oncology |
| spelling | doaj.art-1f15466172dd46e9898d15d49ac2dfb32024-03-30T04:39:32ZengElsevierClinical and Translational Radiation Oncology2405-63082024-05-0146100769Developing and validating a simple urethra surrogate model to facilitate dosimetric analysis to predict genitourinary toxicityRagu Ratnakumaran0Jonathan Mohajer1Samuel J. Withey2Douglas H. Brand3Ernest Lee4Andrew Loblaw5Shaun Tolan6Nicholas van As7Alison C. Tree8The Royal Marsden NHS Foundation Trust, London, UK; Radiotherapy and Imaging Division, Institute of Cancer Research, London, UK; Corresponding author at: Oak Cancer Centre, Royal Marsden Hospital, Downs Road, SM2 5PT, UK.The Royal Marsden NHS Foundation Trust, London, UKThe Royal Marsden NHS Foundation Trust, London, UKDepartment of Medical Physics and Bioengineering, University College London, UKThe Royal Marsden NHS Foundation Trust, London, UKOdette Cancer Centre, Sunnybrook Health Sciences Centre, Toronto, Ontario, CanadaThe Clatterbridge Cancer Centre, Liverpool, UKThe Royal Marsden NHS Foundation Trust, London, UK; Radiotherapy and Imaging Division, Institute of Cancer Research, London, UKThe Royal Marsden NHS Foundation Trust, London, UK; Radiotherapy and Imaging Division, Institute of Cancer Research, London, UKPurpose: The urethra is a critical structure in prostate radiotherapy planning; however, it is impossible to visualise on CT. We developed a surrogate urethra model (SUM) for CT-only planning workflow and tested its geometric and dosimetric performance against the MRI-delineated urethra (MDU). Methods: The SUM was compared against 34 different MDUs (within the treatment PTV) in patients treated with 36.25Gy (PTV)/40Gy (CTV) in 5 fractions as part of the PACE-B trial. To assess the surrogate's geometric performance, the Dice similarity coefficient (DSC), Hausdorff distance (HD), mean distance to agreement (MDTA) and the percentage of MDU outside the surrogate (UOS) were calculated. To evaluate the dosimetric performance, a paired t-test was used to calculate the mean of differences between the MDU and SUM for the D99, D98, D50, D2 and D1. The D(n) is the dose (Gy) to n% of the urethra. Results: The median results showed low agreement on DSC (0.32; IQR 0.21–0.41), but low distance to agreement, as would be expected for a small structure (HD 8.4mm (IQR 7.1–10.1mm), MDTA 2.4mm (IQR, 2.2mm-3.2mm)). The UOS was 30% (IQR, 18–54%), indicating nearly a third of the urethra lay outside of the surrogate. However, when comparing urethral dose between the MDU and SUM, the mean of differences for D99, D98 and D95 were 0.12Gy (p=0.57), 0.09Gy (p=0.61), and 0.11Gy (p=0.46) respectively. The mean of differences between the D50, D2 and D1 were 0.08Gy (p=0.04), 0.09Gy (p=0.02) and 0.1Gy (p=0.01) respectively, indicating good dosimetric agreement between MDU and SUM. Conclusion: While there were geometric differences between the MDU and SUM, there was no clinically significant difference between urethral dose-volume parameters. This surrogate model could be validated in a larger cohort and then used to estimate the urethral dose on CT planning scans in those without an MRI planning scan or urinary catheter.http://www.sciencedirect.com/science/article/pii/S2405630824000466SurrogateUrethraProstate radiotherapyStereotactic body radiotherapy |
| spellingShingle | Ragu Ratnakumaran Jonathan Mohajer Samuel J. Withey Douglas H. Brand Ernest Lee Andrew Loblaw Shaun Tolan Nicholas van As Alison C. Tree Developing and validating a simple urethra surrogate model to facilitate dosimetric analysis to predict genitourinary toxicity Clinical and Translational Radiation Oncology Surrogate Urethra Prostate radiotherapy Stereotactic body radiotherapy |
| title | Developing and validating a simple urethra surrogate model to facilitate dosimetric analysis to predict genitourinary toxicity |
| title_full | Developing and validating a simple urethra surrogate model to facilitate dosimetric analysis to predict genitourinary toxicity |
| title_fullStr | Developing and validating a simple urethra surrogate model to facilitate dosimetric analysis to predict genitourinary toxicity |
| title_full_unstemmed | Developing and validating a simple urethra surrogate model to facilitate dosimetric analysis to predict genitourinary toxicity |
| title_short | Developing and validating a simple urethra surrogate model to facilitate dosimetric analysis to predict genitourinary toxicity |
| title_sort | developing and validating a simple urethra surrogate model to facilitate dosimetric analysis to predict genitourinary toxicity |
| topic | Surrogate Urethra Prostate radiotherapy Stereotactic body radiotherapy |
| url | http://www.sciencedirect.com/science/article/pii/S2405630824000466 |
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