Set-up verification using portal imaging; review of current clinical practice

In this review of current clinical practice of set-up error verification by means of portal imaging, we firstly define the various types of setup erro rs using a consistent nomenclature. The different causes of set-up errors a re then summarized. Next, the results of a large number of studies regardin g patient set-up verification are presented for treatments of patients with head and neck, prostate, pelvis, lung and breast cancer, as well as for ma ntle field/total body treatments. This review focuses on the more recent st udies in order to assess the criteria for good clinical practice in patient positioning. The reported set-up accuracy varies widely, depending on the treatment site, method of immobilization and institution. The standard devi ation (1 SD, mm) of the systematic and random errors for currently applied treatment techniques, separately measured along the three principle axes, r anges from 1.6-4.6 and 1.1-2.5 (head and neck), 1.0-3.8 and 1.2-3.5 (prosta te), 1.1-4.7 and 1.1-4.9 (pelvis), 1.8-5.1 and 2.2-5.4 (lung), and 1.0-4.7 and 1.7-14.4 (breast), respectively. Recommendations for procedures to quan tify, report and reduce patient set-up errors are given based on the studie s described in this review. Using these recommendations, the systematic and random set-up errors that can be achieved in routine clinical practice can be less than 2.0 mm (1 SD) for head and neck, 2.5 mm (1 SD) for prostate, 3.0 mm (1 SD) for general pelvic and 3.5 mm (1 SD) for lung cancer treatmen t techniques. (C) 2001 Elsevier Science Ireland Ltd. All rights reserved.