CASE STUDY | ROYAL BRISBANE AND WOMEN’S HOSPITAL
Use of Motion Management to Model Unmanaged Motion: Dosimetric Consequences of Unmanaged Prostate Motion Assessed Using Real-time Radiotherapy Adaptation Data
Authors:
Scott B. Crowe, Jemma Walsh, Gregory Rattray, Philip Chan, Tanya Kairn, Cancer Care Services, Royal Brisbane and Women’s Hospital, Brisbane, Australia
Summary:
Patient Profile:
| Patient | 78-year-old male |
| Diagnosis | T2c N0 M0 prostate adenocarcinoma |
| Dose | 60 Gy in 20 fractions |
| Case Challenge | Frequent continuous drift of the prostate during treatment |
Methodology:
- Real-time Synchrony® motion data extracted following treatment was used to simulate dose delivery without real-time adaptation.
- Dose distributions were deformed using a voxel-wise deformation vector field that accounted for couch motion interplay.
- Two scenarios were modelled:
- Standard hypofractionated regimen (60 Gy/20 fractions, 6 mm margin).
- Simulated ultra-hypofractionated SBRT regimen (40 Gy/5 fractions, 3 mm margin).
Key findings if the patient had not been treated with motion management:
| Standard Regimen | CTV coverage was maintained even in worst-case drift, but PTV coverage would be compromised without Synchrony |
| SBRT Simulation | Significant underdosage occurred in worst-case scenarios, with CTV V95% dropping to 93.3%, below acceptable limits |
Conclusion:
Implications:
- The study highlights the importance of real-time tracking in maintaining dose accuracy.
- Suggests that narrow margins without motion management may lead to biochemical failure.
- The deformation modelling approach offers a valuable tool for evaluating margin adequacy and guiding treatment planning.
Crowe S B, Walsh J, Rattray G, et al. (April 20, 2025) Use of Motion Management to Model Unmanaged Motion: Dosimetric Consequences of Unmanaged Prostate Motion Assessed Using Real-Time Radiotherapy Adaptation Data. Cureus 17(4): e82620. DOI 10.7759/cureus.82620
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Important Safety Information:
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