ESTRO 2021 Abstract Book

S1652

ESTRO 2021

Purpose or Objective Identify and critically evaluate the literature base on the use of open-face masks in combination with SGRT. Evaluate the impact of the immobilisation on positional stability, patient experience and staff training. Stimulate consideration of alternative immobilisation devices for use with SGRT. To encourage the execution of clinical evaluation studies by SGRT users. Materials and Methods A systematic literature search was undertaken to identify the published evidence on the use of immobilisation in combination with SGRT. Non-immobilised i.e. breast, prostate or articles related to radiosurgery were excluded, resulting in 10 papers for inclusion in the full literature review.

Results

SGRT merits the introduction of open-faced mask immobilisation for patients undergoing head or head and neck radiotherapy. Particular consideration is being given to this approach for patients who suffer from a psychological effect of radiotherapy known as 'mask anxiety', due to the restrictive nature of traditional closed-face masks, however, the results of a weekly survey in a study to evaluate and compare the two types of mask showed no significant differences in levels of anxiety experienced by patients. One study concluded the open-face mask offers direct detection of the patient's skin surface, reducing signaling effects on the surface-scanning performance due to a thermoplastic mask layer, while another study explained set-up variations may be affected by weight loss. The study also states a wide variation of open-face masks are compatible with SGRT, irrelevant of the manufacturer or the amount of skin surface exposed in the mask. The omission of patient feedback is a limitation in the study, as patient feedback provides important insight into the effectiveness of immobilisation and tolerability. Staff training must remain a key consideration when evaluating any new immobilisation and reports show that poor selection of an ROI for SGRT can result decreased positional accuracies. Conclusion Results show that open-face masks are feasible for use with surface-guided imaging, and are comparable to that of closed masks in limiting motion for treatment delivery. The review did not conclude that open-face masks reduce the level of 'mask-anxiety' experienced by the patient however further investigation is required on the reduction in treatment time due to the use of SGRT and the psychological impact this could have on a patient's tolerance for immobilisation equipment. For consistency, it is important with the implementation of any new equipment that extra care is given to staff training and quality assurance procedures. To conclude, the use of open-face masks is feasible in combination with SGRT, however, the potential impact of the new device on patient experience requires further exploration for both adult and paediatric cohorts. PO-1939 The Effect of BMI on the Positional Error in Radiotherapy with Prone Breast Fixator Placement Y. You 1 , X. Li 1 , Z. Cui 1 , Y. Yin 1 1 Shandong Cancer Hospital and Institute, Shandong First Medical University and Shandong Academy of Medical Sciences, Department of radiation oncology, Jinan, China Purpose or Objective To investigate the effect of body mass index (BMI≥18.5) on positional error in prone breast image-guided radiation therapy (IGRT). Materials and Methods