Cone-Beam Computed Tomography (CBCT)-Based Online Adaptive Radiation Therapy (oART) for a Prostate Cancer Patient With Inflammatory Bowel Disease and Bilateral Total Hip Arthroplasty: A Case Report

This case report addresses the complex management of a patient with concurrent prostate cancer, inflammatory bowel disease (IBD), and bilateral total hip arthroplasty, and demonstrates the efficacy of cone-beam computed tomography (CBCT)-guided daily online adaptive radiation therapy (oART) and advanced imaging techniques in overcoming significant treatment challenges. A 68-year-old male with a history of ulcerative colitis and bilateral hip prostheses was diagnosed with high-risk prostate cancer. Conventional radiation therapy modalities, including external beam radiation therapy (EBRT), proton therapy, and magnetic resonance imaging (MRI)-based oART, faced limitations because of the patient's comorbidities and metallic implants. Daily oART, using the Ethos platform (Varian Medical Systems, Palo Alto, CA, USA) with HyperSight™ metal artifact reduction (MAR) imaging, was employed to enhance treatment efficacy. The daily oART treatment on the Ethos platform facilitated the successful delivery of a therapeutic dose while sparing healthy tissues, and the treatment was successful without an IBD flare-up. Daily oART also optimized the target dose while best sparing the critical organs based on the patient's daily anatomy. The HyperSight MAR algorithm significantly reduced imaging artifacts caused by the hip prostheses, enabling accurate identification of the prostate, bladder, and surrounding organs. The oART workflow was delivered without technical challenges, with a total session time of 20 to 30 minutes, similar to our typical prostate patients without hip implants. Despite the complex anatomy and comorbid conditions, the treatment plan met all organ-at-risk constraints and delivered the prescribed dose to the target volumes. Ethos oART with HyperSight provided an effective solution for treating a patient with concurrent prostate cancer, IBD, and bilateral hip arthroplasty. The patient's case was successfully treated without complications, despite such challenging clinical and technical scenarios.