[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 1h to 1h30 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.

MATERIAL AND

METHODS

The files of 33 patients (including 13 with prostate cancer) treated from November 2010 to February 2011 on a Varian™ Clinac IX accelerator with an OBI™ 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 5mm, 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 3mm 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 4mm was 97% (CI95±2%) vs. 57% (CI95±10%) for measures equal to or higher than 5mm (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 3mm 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.