title: Consistent collimator overlaps in field matching with computer-controlled x-ray collimators.
abstract: Consistent collimator overlaps in field matching with computer-controlled asymmetric x-ray collimators have been observed and investigated. The results indicate that, although this consistent overlapping is small and within manufacturer's +/- 1 mm discrepancy specification, it can produce more than 10% cold spots at matchlines if unheeded. This undesirable dose inhomogeneity, however, can be improved to within +/- 3% with a simple and practical solution of artificially offsetting the collimators by exactly the same amount (e.g., 1 mm) they overlap.
authors.affiliation: Loyola-Hines Department of Radiotherapy, Loyola University, Maywood, IL 60153, USA.
authors.forename: P C
authors.initials: PC
authors.lastname: Lee
mesh_terms: D005373:Film Dosimetry; D006801:Humans; D010315:Particle Accelerators; D011879:Radiotherapy Dosage; D011882:Radiotherapy, High-Energy / Q000295:instrumentation* / Q000379:methods; D013679:Technology, Radiologic