Prostate Stereotactic Body Radiotherapy With Synchrony®-Based Fiducial Tracking on Radixact® X9

Prostate cancer, when detected early, can be either actively observed or treated radically based on clinical, pathological, and imaging features. Radical treatment options include radical prostatectomy, radical radiation as external beam radiotherapy (EBRT), or brachytherapy. EBRT for prostate cancer can be given in different ways. It may be delivered in smaller doses over several weeks, known as conventionally fractionated radiation therapy (CF-RT), or in larger doses over fewer sessions, as in moderately hypofractionated radiotherapy and ultra hypofractionated radiotherapy, also known as stereotactic body radiation therapy (SBRT). Recent studies have shown that SBRT is non-inferior to CF-RT, and the National Comprehensive Cancer Network guidelines also suggest SBRT as a treatment option for localized disease. As SBRT uses a high dose per fraction for treatment, it requires a very tight margin around the planning target volume and intrafractional motion management to prevent the organs at risk from receiving a high dose and subsequent toxicities developing from it. In this case series, we report our clinical experience with prostate SBRT using the Radixact® X9 (Accuray, Sunnyvale, CA, United States) tomotherapy machine with Synchrony® fiducial tracking for real-time motion tracking and correction.