Partial delegation to radiation therapists of the control by onboard imaging of patient positioning

Purpose. - Daily set up of patients with prostate cancer using orthogonal kV/kV imaging and weekly set up control require 1 h to 1 h 30 of off line revision by a radio-oncologist per day and per accelerator. The aim of this study was to evaluate the possibility to delegate this control to radiation therapists. Materiel and methods. - The files of 33 patients (including 13 with prostate cancer) treated from November 2010 to February 2011 on a Varian (TM) Clinac IX accelerator with an OBI (TM) system were evaluated. Radiation therapists made the daily kV/kV imaging. Radiation therapists made the online control by kV/kV for patient repositioning and radio-oncologists made the offline reviews; the results were compared and analysed (seven radiation therapists and seven radio-oncologists). For an isocentre displacement of 5 mm, the radiation therapist had to call the radio-oncologist to make a medical decision (treatment or patient displacement). The difference of measures and the concordance of decisions between radiation therapists and radio-oncologists were calculated. Results. - Five hundred and fifty-six measures were made for 33 treatments, including 226 measures for prostate cancer treatment. The difference of measures between radiation therapists and radio-oncologists was 3 mm or less in 93.7% for all treatments and 96.2% for prostate cancer treatment. The concordance of decision between radiation therapists and radio-oncologists for measures up to 4 mm was 97% (CI95 +/- 2%) vs. 57% (CI95 +/- 10%) for measures equal to or higher than 5 mm (P < 0.0001). Conclusion. - Radiation therapists are able to do daily set up using kV/kV on the bony structures of patients with prostate cancer, with a risk of disagreement higher than 3 mm less than 4%. The weekly set up controls (different primaries) can be delegated to the radiation therapists, subject to an accurate procedure using a medical alert for a given threshold. Training and competence certification are required to secure the process. (C) 2013 Published by Elsevier Masson SAS on behalf of the Societe francaise de radiotherapie oncologique (SFRO).