title: Precision of determining compliance with prescribed fields from conventional portal films.
abstract: Three hundred and seventy measurements of field placement errors (FPEs) have been made by a total of 16 observers on 20 prescription-treatment film pairs taken during routine radiotherapy for cancer of the prostate. Analysis of the distributions of the measured FPEs has yielded the precision of the measurement under a variety of conditions. We report here the influence on the precision of determining FPEs of the following factors: the clinical duties of the observers, the quality of the treatment film, the relative magnification of prescription and treatment films, and whether double-exposure techniques were employed.
authors.affiliation: Department of Medical Physics, Manitoba Cancer Treatment and Research Foundation, Winnipeg, Canada.
authors.forename: P B
authors.initials: PB
authors.lastname: Dunscombe
authors.forename: K
authors.initials: K
authors.lastname: Fox
mesh_terms: D006801:Humans; D008297:Male; D011471:Prostatic Neoplasms / Q000532:radiotherapy; D011878:Radiotherapy / Q000295:instrumentation*; D014962:X-Ray Film