Reproducibility of Field Alignment in Radiation therapy: A Large-Scale Clinical Experience

Abstract

A specially designed cassette which gives an excellent quality of portal films has been used to determine the set-up accuracy and uncertainties in treatment alignment during full-course radiation therapy on patients treated for some common malignant diseases. An analysis of a comparison between simulator films and portal films is also presented. for various diagnoses treatment-to-treatment positioning varied with an average standard deviation of 3.5 mm despite the use of laser alignment and good patient fotation.

Key Words:

• Radiation therapy
• quality control
• patient positioning
• localization uncertainties
• portal films