SU-GG-I-135: Assessment of the Correlation between Daily Set-Up Patient Positioning Correction Values of an On-Board KV Imaging System and the Radiation Technologist Rank



Purpose: To examine the daily patient set-up positioning error vs. the radiation technologist rank, by deriving it from the XVI image fusion correction values. Method and Materials: A set of 5 prostate, 5 head & neck and 4 lung cancer patients had been taken for this comparison. All of the patients were treated in IMRT Step & Shoot technique. For each patient the following data was extracted: (1) 10 XVI scans randomly picked and three parameters were taken, the table shift in 3 axis: longtitudal, lateral, vertical. (2) The names of the radiation technologists correlating to the date of the XVI scan. Three intervals of fusion correction were defined: 2–3 [mm], 3–5 [mm], greater then 5 [mm]. Radiation technologists were ranked by compiling a set of categories such as: chronological time at work, overall assessment of the institute senior staff in a scale of 1–5 (1-High Rank; 5-Low Rank). Results: There is a definitive match between the value of the correction and the number of corrections in total per patient and the radiation technologist rank. Radiation technologists that were ranked 4 or 5 constitute most of the fusion corrections above 3 and 5 [mm] in patients positioning. A combination pair of radiation technologists that were ranked as 4 or 5 increased the correction in two forms: (1) more then one axis was corrected (2) the value of the correction was high. A combination pair of a median rank and high rank radiation technologist yielded better results then a pair of a median rank and low rank radiation technologist. Conclusion: This work clearly indicates the on-going strive for the education of the technical staff, as a vital link in patient positioning which leads to administrating the correct dose to a patient, in an accurate treatment modality such as IMRT.