Clinical Implementation of PSMA-PET Guided Tumor Response-Based Boost Adaptation in Online Adaptive Radiotherapy for
Ruiqi Li1, Mu-Han Lin1, Nghi C Nguyen2
1Department of Radiation Oncology, The University of Texas Southwestern Medical Center, Dallas, TX 75235, USA.
Cancers
|September 13, 2025
Summary
This study demonstrates that using PSMA-PET imaging to guide adaptive radiotherapy for high-risk prostate cancer is feasible. This approach allows for personalized dose adjustments, potentially reducing side effects.
Area of Science:
- Radiation Oncology
- Medical Imaging
- Prostate Cancer Treatment
Background:
- High-risk prostate cancer (HRPCa) requires precise radiotherapy delivery.
- Stereotactic ablative radiotherapy (SABR) offers dose escalation but requires accurate tumor targeting.
- Adaptive radiotherapy (ART) aims to adjust treatment based on daily anatomical changes and tumor response.
Purpose of the Study:
- To assess the feasibility and clinical utility of integrating sequential PSMA-PET imaging into an adaptive workflow.
- To evaluate response-based dominant intraprostatic lesion (DIL) boosting in HRPCa treated with SABR.
- To determine if PSMA-PET imaging can guide personalized dose adjustments within an offline-online ART framework.
Main Methods:
- Prospective trial using MR- or CBCT-guided ART systems for 5-fraction SABR with DIL boost.
- Sequential PSMA-PET imaging after neoadjuvant androgen deprivation therapy (nADT) and fraction 3 SABR.
- Refinement of DIL boost volumes (GTVmb1, GTVmb2) based on PSMA-PET response, using a %SUVmax threshold approach.
- Comparison of dosimetric plans using initial GTV (GTVinitial) versus response-adapted GTVs.
Main Results:
- Seamless integration of PSMA-PET-guided GTV refinements into ART workflows without increasing treatment time.
- Significant reduction in DIL GTV volumes from GTVinitial (11.4 cc) to GTVmb1 (4.1 cc) and GTVmb2 (3.0 cc).
- Meaningful reductions in organ-at-risk (OAR) doses, including rectal wall (up to 12 Gy reduction) and bladder wall (D0.035 cc reduced from 52.3 Gy to 42.9 Gy).
Conclusions:
- PSMA-PET-guided adaptive microboosting is feasible and effective for HRPCa SABR.
- Standard MR-Linac and CBCT systems can be utilized for biology-driven dose personalization.
- This approach has the potential to reduce treatment toxicity in high-risk prostate cancer patients.
