Assessment of set-up discrepancies using daily portal imaging during radiotherapy treatment for patients with spine and bone metastases

Abstract

AbstractIt is well established that patients with bone metastases get good pain relief from radiotherapy. The aim of treatment is to achieve maximum pain relief with minimum morbidity. Accuracy and reproducibility of the patient’s position are fundamental to the successful delivery of radiation therapy. It has been recognised for many years, that the accuracy of patient positioning will improve the success of radiation treatment. A previous study carried out in the department showed that the use of only a single tattoo for the set-up of palliative patients resulted in poor accuracy. The aim of this study was to assess if the addition of extra skin marks improved the set-up accuracy of palliative patients being treated for spine and bone metastases. A protocol was implemented detailing the extra skin marks to be used. Daily portal images were acquired and analysed retrospectively using anatomy matching. The results obtained were then compared with those of the previous study. The use of extra skin marks resulted in a total of 45% of images within 5 mm tolerance compared with 36% of images in patients treated with a single centre tattoo. Also, the number of images with deviations greater than 15 mm was reduced by more than 50% with the addition of extra skin marks. This study has shown that extra skin marks do increase the set-up accuracy in palliative patients treated for spine and bone metastases. Therefore, the practice of using extra skin marks has become standard protocol for all palliative patients within the department.