Main Session
Sep
28
PQA 04 - Breast Cancer, Patient Reported Outcomes/QoL/Survivorship, Functional Radiation Medicine, Hematologic Malignancies, Palliative Care, and International/Global Oncology
Presenter(s)
Madeline Evans, BS - UAB Heersink School of Medicine, Birmingham, AL
M. Evans1, C. Stanley2, and M. Soike3; 1The University of Alabama at Birmingham Heersink School of Medicine, Birmingham, AL, 2University of Alabama at Birmingham, Birmingham, AL, 3University of Alabama at Birmingham Department of Radiation Oncology, Birmingham, AL
Purpose/Objective(s):
Low dose radiotherapy (LDRT) for osteoarthritis employs doses of radiation unlikely to incur toxicity for patients while offering symptomatic relief in 60-70% of patients. The optimal dose per fraction has not been established for symptomatic relief, ranging from 5 cGy to 100 cGy per fraction to achieve benefit. Given the wide uncertainty in doses and minimal risk of toxicity with LDRT, modern treatment techniques utilizing 3D conventional planning and CT simulation may not be clinically necessary. Since 2024, our single institution has treated patients with 2-dimensional techniques without CT simulation. We hypothesized our response rate with a 2-dimensional technique would be similar to reported literature of 65% +/- 10%. We also report toxicity and experiences with a sim free workflow.Materials/Methods:
Patients were referred for consideration of LDRT for osteoarthritis. At consultation, treatment fields and treatment depth (separation) were determined using calipers to measure joint space, using pre-existing radiographs of affected joints when available. Joint pain for each isocenter was assessed on a scale of Likert scale of 1-10. Patients were scheduled for their first fraction. Given the field size determined at time of consult, dosimetry calculated monitor units required for treatment prior to first fraction. Patients were treated with 300 cGy in 6 fractions, 2 fractions delivered weekly. At first fraction, megavoltage portal images confirmed the treatment field. Three months after treatment, patients were assessed for treatment response in each affected joint on a scale of 1-10. A treatment response was defined as any pain response that was >3 point reduction compared to prior.Results:
Twenty-eight patients and 51 joints were irradiated from November 2024-October 2025. At three month follow up, 56% of joints achieved a Likert pain response of 3 points or greater and nine joints were retreated, six of which sustained additional benefit. One misadministration occurred when a right knee was treated twice during the same session. The 56% response rate was considered within the range of acceptable treatment response. Only one patient observed nail changes after treatment of her hand, otherwise, no other toxicities occurred.Conclusion:
Two-dimensional, CT-sim free LDRT yielded cost effective and comparable results to historical reports of treatment of osteoarthritis with a near 56% improvement in symptoms at 3 months after treatment. The misadministration may have been prevented by use of image guidance and conforming to a three-dimensional treatment planning workflow for therapy. After one year of piloting a CT sim free workflow for LDRT, the department transitioned to conventional CT simulation based LDRT to align more closely with standard practice procedures and decrease the likelihood of future misadministration events.