(P121) Image-Guided Radiation Therapy Utilization and Practice Patterns: Results From a National Survey of ASTRO Membership

April 30, 2015

IGRT use is widespread, without standardization of pretreatment imaging modality, frequency, or verification process. Additionally, PTV margin size selection does not appear to be based on IGRT frequency or method of verification. Further research aimed at optimizing IGRT techniques is needed to ensure accurate, safe, timely, and cost-effective treatment delivery.

Nima Nabavizadeh, MD, David A. Elliott, MD, Aaron Kusano, MD, Yiyi Chen, PhD, Timur Mitin, MD, PhD, John M. Holland; Oregon Health and Science University; University of Washington

INTRODUCTION: Image-guided radiation therapy (IGRT) practices differ widely across institutions, with no consensus regarding ideal pretreatment imaging modality, frequency, or verification process. The purpose of this study is to survey clinical IGRT practice patterns and their impact on clinical workflow.

METHODS: A total of 5,979 surveys were emailed to the membership of the American Society of Radiation Oncology (ASTRO). The disease site–specific survey consisted of questions pertaining to planning target volume (PTV) margins, pretreatment image guidance modality/frequency, and method of image verification, as well as questions regarding the utility and value of IGRT. Online image verification was defined as images checked and corrected prior to the day’s treatment. Offline image verification was defined as images obtained prior to treatment and then verified prior to the following day’s treatment. Associations between IGRT practice patterns and PTV margin size were examined using a linear regression model.

RESULTS: Of 671 responses (11%), 70 were nonphysician, resulting in 601 evaluable responses. The majority of respondents used IGRT (99%) for at least one fraction, with cone-beam computed tomography (CBCT) being the most commonly used modality (85%). Daily CBCT was obtained most frequently for intact prostate (63%), followed by prostatic fossa (60%), head and neck (H/N) (52%), pelvic intensity-modulated RT (51%), lung (50%), esophagus (40%), central nervous system (39%), and breast (7%). Regardless of imaging modality, daily online or offline image verification was the most common schedule (range: 72%–96% daily, 4%–24% weekly, and 1%–3% first few fractions only). Online image verification was most common for H/N (92%) and least common for breast (77%), with first-few-fractions–only online schedules most common for all disease sites except breast. The majority of respondents felt comfortable with therapists verifying IGRT independent of a physician (54%) and did not believe IGRT techniques negatively impacted clinical productivity (53%) or the physician-patient relationship due to excessive interruptions (57%). Additionally, the majority of respondents agreed that for pediatric cases, the benefits of IGRT outweighed the risks of additional radiation exposure (85%). No association was seen between IGRT frequency or method of verification and PTV margin size (P > .05 for all comparisons).

CONCLUSION: IGRT use is widespread, without standardization of pretreatment imaging modality, frequency, or verification process. Additionally, PTV margin size selection does not appear to be based on IGRT frequency or method of verification. Further research aimed at optimizing IGRT techniques is needed to ensure accurate, safe, timely, and cost-effective treatment delivery.

Proceedings of the 97th Annual Meeting of the American Radium Society - americanradiumsociety.org