Guidelines and workflow for virtual simulation.

Abstract

49 Background: An important component of radiation treatment planning is the CT simulation which involves several steps including patient positioning, imaging in the treatment position, and placement of an isocenter, a point through which the central rays of the radiation beams pass. As radiation therapy is an important component of palliative treatment for metastatic cancer, some patients require multiple courses which may be temporally proximate. This creates a burden for patients who may be challenged with regard to mobility, distance, and logistics coordinating travel to the department. We sought a clinical workflow that maintains the integrity of the simulation process but allows the potential use of previously obtained treatment planning imaging to create a new treatment plan (i.e. virtual CT simulation). We present our workflow and experience here. Methods: A multidisciplinary group developed a virtual simulation workflow and identified critical criteria to safely and reliably proceed with virtual simulation. These included: time from initial CT simulation (< 14 days), adequacy of patient positioning and immobilization, as well as appropriate inclusion of the entire “virtual” planning treatment volume (PTV) and organs at risk (OARs) in the original scan. Specific virtual simulation care paths were created in treatment planning software (Aria®, Varian Medical Systems) for case tracking. A pilot was initiated to monitor the workflow for the first 10 patients and corrections to the workflow were made. Thereafter the program was randomly audited and the QA reporting system monitored for reported error events. Results: The virtual simulation workflow pilot was initiated in June 2020. Of the first 50 virtual simulation requests, 48 were approved (96%). Two cases were denied due to inadequate immobilization. There was only one event reported pertaining to set up uncertainty requiring clarification from physics. Conclusions: Given the success of the virtual simulation criteria and workflow we will continue this practice and will monitor the cases as well as RISQ events closely. Based on feedback we have received we will expand the window of time to request a virtual simulation from 14 days to 21 days after original simulation and will also allow for up to 3 virtual isocenters to be placed.