Valutazione dell'accuratezza del posizionamento nell'irradiazione della mammella con tecnica isocentrica utilizzando un sistema elettronico per la acquisizione delle immagini portali

Translated title of the contribution: Evaluation of the accuracy of patient positioning in breast irradiation with an isocentric set-up and an on-line portal imaging device

Carlo Greco, Maria Grazia Brambilla, Roberto Orecchia

Research output: Contribution to journalArticle

Abstract

This study investigated the accuracy of daily patient positioning in an isocentric set-up for breast irradiation. This was achieved through the assessment of both systematic and random errors measured as discrepancies between reference simulation images and portal images obtained with an on-line electronic portal imaging device (EPID). To this end, 10 portal images for each of the tangential fields were obtained in 12 consecutive patients and the images were compared to reference simulation films with dedicated software tools provided with the EPID. The discrepancies measured for each set of images were analyzed statistically. Most variations in each series both in terms of cranio-caudal and of lateral displacement appeared to be random, with mean standard deviations of 2.3 and 2.8 mm, respectively. Such variations between reference fields and portal images tend to counteract one another and do not usually play a significant role in the overall accuracy of patient set-up. In some cases, however, the distribution of the variations occurred in a well-defined pattern indicating a systematic error in patient positioning. This study shows that our set-up technique for breast irradiation is relatively accurate and reproducible, and most of the observed errors were below the 5 mm cut-off level, but it stresses the need of accurate quality assurance programs in radiotherapy. Electronic portal imaging devices are excellent tools for fast portal image acquisition, and permit the accurate assessment of discrepancies with respect to reference images.

Translated title of the contributionEvaluation of the accuracy of patient positioning in breast irradiation with an isocentric set-up and an on-line portal imaging device
Original languageItalian
Pages (from-to)254-259
Number of pages6
JournalRadiologia Medica
Volume93
Issue number3
Publication statusPublished - Mar 1997

ASJC Scopus subject areas

  • Radiology Nuclear Medicine and imaging

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