hrvatski

Utjecaj pogreške u položaju bolesnika tijekom zračenja zdjelice na raspodjelu doze

An external beam radiotherapy (EBRT) using megavoltage beams of linear accelerator is usually treatment of choice for the cancer patients. The goal of EBRT is to deliver prescribed dose to the target volume, with as low as possible dose to the surrounding healthy tissue (1). A large number of procedures and different professions involved in radiotherapy process, uncertainty of equipment and daily patient set-up errors can cause difference between planned and delivered dose (1, 2, 3). We investigated which part of this difference is caused by daily patient set-up errors. Daily set- up errors for 35 patients were measured (1, 2, 3). Those set-up errors were simulated on 5 patients, using 3D treatment planning software XiO (CMS Inc., St. Louis, MO). The differences in dose distributions between planned and shifted ‘geometry’ were investigated. Additionally, errors influence on treatment plan selection was checked analyzing change in dose volume histograms, conformity index (CI) and homogeneity index (HI). Simulations showed that patient daily set-up errors can cause significant differences between planned and actual dose distributions. Moreover, for some patients those errors influenced choice of treatment plan since CI fell under 95%. Surprisingly, HI was not as sensitive on set-up errors. The results showed the need for minimizing daily set-up errors by quality assurance programme

radioterapija ; kontrola kvalitete ; položaj bolesnika ; raspodjela doze

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