Real-time Online Matching in High Dose-per-Fraction Treatments: Do Radiation Therapists Perform as Well as Physicians?

Abstract

Purpose: In our department, for high dose-per-fraction treatments such as stereotactic body radiation therapy, we require a physician to perform the pretreatment on-board imaging match. The purpose of this study was to determine whether patient-matching positioning performed by radiation therapists (RTTs) is as accurate as that performed by physicians.

Methods and materials: Sixteen RTTs and 5 physicians participated in this study. Data were collected from 113 patients, totaling 324 measurements. A total of 60 patients were treated for bone lesions and 53 for soft-tissue lesions, such as lung and liver. Matching was performed using kV-kV imaging for bones and cone beam computed tomography for soft tissue. All treatments were delivered on Varian linear accelerators. The initial match was performed by the RTTs, and the shifts were noted. Subsequently, the match was reset, and the physician performed an independent match blinded to the RTT match. Physician shifts were applied for treatment. We used the Wilcoxon rank sum test to determine the statistical significance between RTT and physician shifts.

Results: The differences in patient shifts between physicians and RTTs were calculated in 3 translational 1 one rotational axis. The average vector shift was 0.88 ± 0.57 cm versus 0.91 ± 0.57 cm for RTTs versus physicians, respectively. Neither the average vector nor the individual axis shifts were statistically significantly different (P > .2). There was no significant difference when testing for bony or soft lesion matches separately.

Conclusions: RTT on-board imaging matching is as accurate as physician matching for both bone and soft tissue lesions. On the basis of these results, RTTs are as qualified as physicians to perform a pretreatment match. Thus, it may be feasible for the RTTs to perform the match and the physician to review it offline after treatment without being present at the machine during treatment. Our results show that this approach does not compromise patient safety.