ESTRO 2020 Abstract book

S328 ESTRO 2020

Poster discussion: PH: Implementation of new techniques 2

PD-0546 Ten years critical re-evaluation of a Failure mode effect analysis in a radiotherapy department P. Mancosu 1 , C. Signori 2 , E. Clerici 1 , T. Comito 1 , F. De Rose 1 , S. Ferrante 1 , M. Ferrara 1 , C. Galdieri 1 , C. Iftode 1 , P. Navarria 1 , A. Stravato 1 , M. Scorsetti 1,3 1 Humanitas Research Hospital, Radiotherapy and Oncology, Rozzano-Milano, Italy ; 2 Humanitas Research Hospital, Healthcare Directorate, Rozzano-Milano, Italy ; 3 Humanitas University, Biomedical Sciences, Pieve Emanuale-Milano, Italy Purpose or Objective The European directive 2013/59/EURATOM recommends that the quality assurance program in RT should include a study of the risk of accidental or unintended exposures. In our institute, a first failure mode and effects analysis (FMEA) was performed in 2008. The aim of this study was to critically re-evaluate the RT process after 10 years. At our knowledge, this is the first time an FMEA process was critically reviewed. Material and Methods A working group including radiation oncologists, physicists, RTTs, secretaries, and nurses performed a deep process analysis and evaluated the possible Failure Modes (FMs) of the RT process. For each FM, the estimated frequency of occurrence (O – range 1-4), the expected severity of the damage to the patient (S – range 1-5) and the detectability (D – range 1-4) were scored. Critical index (CI) was obtained as CI=OxSxD. Data were compared to the 2008 In 2008, the highest CIs were: (i) Error in patient identification (CI=48); (ii) incompleteness of the first examination (CI=29); (iii) prescription of an inadequate support therapy (CI=28). Actions adopted to reduce the first three CIs were: (i) a barcode verification system inside the bunker to check the patient identification and avoid mistreatments; (ii and iii) new information technology system with drop down menu and a reorganization of the physicians’ agenda. In the 2019 analysis, the first three CIs were reduced. In particular, patient identification CI was reduced to 13 (11 th CI score). The new highest CIs were: (a) non-adequate target contouring (CI=36) and (b) under-estimation of symptoms on other regions undergoing RT (CI=34). Possible reasons could be: (a) the higher dose conformity to the designed volume achievable thanks to the inverse modulated treatments, (b) the increase of long survivals that could require new RT treatments. Conclusion The FMEA analysis allowed taking actions to reduce the highest CI values. The 10 years analysis revealed new crucial points in a continuous iterative process. PD-0547 National EndtoEnd (E2E) dosimetry intercomparison for lung stereotactic radiosurgery in Switzerland edition. Results

Conclusion cPG D98% and high dose received by small OC volumes were found to impact most on G≥2 aSD, with age and smoking history acting as a dose-modifying factor. Findings on the development population were confirmed in a prospectively collected validation cohort, with peculiar validation of discriminative power and of effect size of dosimetric factors, thus gaining confidence on factors to be considered while optimizing RT.

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