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Location: Marriott Marquis
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PQA 09 - PQA 09 Hematologic Malignancies and Digital Health Innovations Poster Q&A

3383 - Enhancing Adaptive Radiotherapy with Dynamic Prescription Modifications

Tuesday, October 1, 2024
4:00 PM – 5:00 PM ET
Location: Hall C

Screen: 18

P. M. Jenkins1,2, S. R. Miller II1,2, and R. Boggula1,2; 1Wayne State University School of Medicine, Detroit, MI, 2Karmanos Cancer Institute, Detroit, MI

Purpose/Objective(s): This study aims to enhance adaptive radiotherapy through dynamic prescription modifications as with even adaptive radiotherapy there is a risk that targets can be underdosed. By evaluating the cumulative doses in the adaptive treatment management monitoring workspace, we plan to adjust the prescription dose accordingly. This approach ensures that the treatment is precisely tailored to the patient’s evolving dose distribution throughout the typical treatment course. Materials/

Methods: The adaptive treatment management monitoring workspace was utilized to review data from five patients treated using adaptive radiotherapy prescribed to a dose of 6000 cGy delivered in 20 fractions (Fx)(300 cGy/Fx). The delivered dose to the planning target volume (PTV) and organs at risk (OARs) were assessed at every fifth fraction to guide prescription modifications, aligning treatments with patients evolving dose distributions.
Results: Our study set optimal coverage for the PTV to V100% >= 95% of the prescription dose. For OARs, the tolerances were V4500 <= 45% for both the bladder and rectum. Analysis, presented in Table 1, demonstrated the potential to adjust the prescription dose by an average of 4.2% with a standard deviation of 0.006 for every 5 fractions (minimum adjustment 3.1%, maximum adjustment 5.0%) to conservatively attain coverage of the PTV to V100% >= 100% while safely maintaining the predefined constraint margins for the OARs.
Conclusion: Leveraging accumulated dose for patients on-treatment is a quick check that can be used to maximize dose to PTV or reduce dose to OARs during radiation treatment. Our evaluation indicates the opportunity to adjust the dose every five fractions. With adaptive radiotherapy becoming increasingly streamlined, realizing this potential soon seems feasible.

Abstract 3383 – Table 1

Table 1: Hypofractionated Prostate Adaptive RT - Accumulated Dose Fractions 1-5 Fractions 6-10 Fractions 11-15
Patient 1 PTV 6000 96.8% 96.9% 95.6%
OAR:Bladder 5.8% 4.6% 4.4%
OAR: Rectum 12.5% 10.2% 10.0%
Patient 2 PTV 6000 95.0% 95.0% 95.0%
OAR:Bladder 16.9% 15.5% 16.4%
OAR: Rectum 11.9% 11.1% 9.2%
Patient 3 PTV 6000 96.5% 95.7% 96.0%
OAR:Bladder 16.4% 13.1% 16.5%
OAR: Rectum 8.4% 10.3% 11.8%
Patient 4 PTV 6000 96.3% 96.3% 96.0%
OAR:Bladder 13.7% 17.7% 14.8%
OAR: Rectum 11.8% 7.9% 10.6%
Patient 5 PTV 6000 95.8% 95.7% 95.5%
OAR:Bladder 5.1% 4.2% 5.2%
OAR: Rectum 3.8% 4.5% 6.3%