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Offline adaptive radiotherapy for bladder cancer using cone beam computed tomography
1Division of Radiation Oncology, Peter MacCallum Cancer Center, Melbourne, Victoria, Australia. farshad.foroudi@petermac.org
Journal of Medical Imaging and Radiation Oncology
|June 17, 2009
Summary
Adaptive radiotherapy using cone beam CT (CBCT) improved clinical target volume coverage for bladder cancer patients. Offline adaptive planning enhanced dose delivery compared to conventional methods, indicating potential for online adaptive strategies.
Area of Science:
- Radiation Oncology
- Medical Physics
- Urologic Oncology
Background:
- Conventional radiotherapy for bladder cancer relies on static treatment planning, potentially leading to suboptimal target coverage due to anatomical variations.
- Adaptive radiotherapy (ART) aims to adjust treatment based on daily anatomical changes, potentially improving outcomes.
- Cone beam CT (CBCT) offers volumetric imaging during treatment, enabling adaptive planning.
Purpose of the Study:
- To evaluate the feasibility and dosimetric benefits of an offline adaptive radiotherapy approach using daily CBCT for bladder cancer.
- To compare offline adaptive, online adaptive, and conventional planning strategies regarding clinical target volume (CTV) coverage and normal tissue sparing.
- To assess the impact of bladder volume variations on treatment planning and delivery.
Main Methods:
- A retrospective analysis was performed on five muscle-invasive bladder cancer patients undergoing radical radiotherapy.
- Conventional plans were compared with offline adaptive plans created using CBCT data from the first five fractions.
- A theoretical online adaptive protocol was modeled, considering daily soft-tissue positioning and bladder size for plan selection.
Main Results:
- Offline adaptive planning significantly improved CTV coverage from 60.1% to 94.7% compared to conventional planning.
- Online adaptive planning showed varying CTV coverage (34.9% to 90.7%) depending on bladder volume.
- Online adaptive radiotherapy reduced irradiated normal tissue volume due to smaller planning target volume margins (0.5 cm vs. 1.5 cm).
Conclusions:
- Offline adaptive radiotherapy improves CTV coverage and conformity in bladder cancer patients with significant anatomical variations.
- Online adaptive radiotherapy demonstrates potential for further optimization of dose delivery and normal tissue sparing.
- Further research into online adaptive radiotherapy for bladder cancer is warranted to refine protocols and confirm clinical benefits.
