title: Verification of optical distance indicator accuracy.
abstract: The purpose of the optical distance indicator, or rangefinder, is to set the patient at a certain distance from the radiotherapy source when using either fixed SSD or an isocentric technique. If the distance that is set is not accurate, then the tumor dose calculated using this distance is also incorrect. Unfortunately, an ODI that is not properly aligned may show an accurate reading on a flat surface and may give an inaccurate reading on a sloped surface.
authors.affiliation: Medical College of Georgia, Georgia Radiation Therapy Center, Augusta 30912-3965.
authors.forename: S
authors.initials: S
authors.lastname: Burch
authors.forename: A M
authors.initials: AM
authors.lastname: Vann
authors.forename: J
authors.initials: J
authors.lastname: Arazie
mesh_terms: D006801:Humans; D008961:Models, Structural; D055095:Optics and Photonics / Q000295:instrumentation*; D011785:Quality Assurance, Health Care; D011878:Radiotherapy / Q000592:standards*; D011879:Radiotherapy Dosage