ESTRO 2021 Abstract Book

S1691

ESTRO 2021

PO-1991 Impact of evaluation-decision form in lung cancer patients receiving stereotactic body radiotherapy R. Bultijnck 1 , A. Van Damme 1 , F. Vanhoutte 1 , E. Elamin 1 , K. Vandecasteele 1 , P. Berkovic 2 , M. van Eijkeren 1 , Y. Lievens 1 1 Ghent University Hospital, Radiotherapy, Ghent, Belgium; 2 UZ Leuven, Radiotherapy, Leuven, Belgium Purpose or Objective Stereotactic body radiotherapy (SBRT) is the treatment of choice for patients with peripheral early stage non-small cell lung cancer (ES-NSCLC) ineligible for or unwilling to undergo surgery. SBRT using risk-adapted dose-fractionation schedules are safe and results in limited toxicity, yet its introduction may be prone to learning curves and adherence to dose constraints remains crucial. The aim of the current study was to evaluate the impact of implementing formal quality and decision checks in plan evaluation, based on evidence-based recommendations, on the dose prescription and clinical outcome of ES-NSCLC patients receiving SBRT in daily practice. Materials and Methods To improve dose prescription and treatment plan quality, an evaluation and decision form was developed and implemented in daily practice since October 2010. All patients with peripheral ES-NSCLC treated in the early implementation phase of SBRT, centered around the introduction of the form were included in this retrospective review. Patients received SBRT before using the form were allocated to the control group whereas those received SBRT after its implementation to the intervention group. Patient characteristics (age, gender, Karnofsky Performance Status, co-morbidities, tumor stage and histology, and dose prescription were documented. Subacute (radiation pneumonitis) and 7-year late toxicity (i.e. dysphagia, skin, soft tissue, chest wall pain, lung fibrosis, dyspnea, cough, lung pneumonitis, pleural effusion, bronchopulmonary hemorrhage brachial plexopathy) was scored using the CTCAE v4.0 toxicity scoring system. The evidence-based predefined form made a distinction between minor and major deviations. Our primary outcome was set to evaluate the prevalence of minor and major deviations and its impact on toxicity outcomes. Results In total, 86 ES-NSCLC patients were included (43 patients per group). No significant differences in baseline patient and tumor characteristics were observed between cohorts except for age and histology. In the intervention group, the majority of patients (70%) received a prescription dose of 3x20Gy, followed by 8x7,5Gy (19%), while the proportion was inversed in the control group (resp. 42% and 58%). A significant difference (p<0,001) was observed for ‘major’ deviations between groups, i.e. 23% in the intervention group compared to 65% in the control group, but not for minor deviations (p=0.158) (see figure 1A,B). Neither radiation pneumonitis (p=0.148), nor maximum chronic toxicities was significantly differenced. Figure 1A&B

Conclusion The implementation of an evaluation and decision form for SBRT in ES-NSCLC improved adherence to evidence-based dose constraints and stimulated the use of fractionation schemes with high biologically effective dose, without negatively impacting toxicity. Therefore, it can be an effective approach to support safe and qualitative radiotherapy in daily clinical practice. PO-1992 Development of an application programming interface for quality assurance of card check process. E.P.P. Pang 1 , C.S. Wong 2 , F.C.L. Ngoi 1 , Y.B. Omar 1 , S.A. Gan 2 1 National Cancer Centre Singapore, Division of Radiation Oncology, Singapore, Singapore; 2 National Cancer Centre Singapore, Department of Cancer Informatics, Singapore, Singapore Purpose or Objective An in-house application programming interface (API) ( RT plan check ) that caters to a multi-vendor environment to improve consistency and quality of checks was developed. This vendor-agnostic API aims to streamline and automate key steps within the entire quality assurance (QA) checks process. Materials and Methods Existing environment involves treatment delivery via 4DiTC with Varian Linear Accelerators and recording of all delivered treatment parameters on the primary Oncology Information System (OIS) (i.e. Mosaiq (Elekta Pte Ltd)). A universal web- based interface (Figure 1) was designed to consolidate various approved and delivered treatment related information from multiple treatment sessions into a single platform with automated data field matching function integration performed to verify the delivered treatment parameters with the prescribed treatment plan. Data mismatch between approved and delivered field parameters would be highlighted. Additionally, discrepancies between the applied setup corrections based on image registrations with reference to the corresponding action-levels of imaging protocols would also prompt further investigation. The number of system clicks required to complete an independent card check using the API was reviewed.