title: Introducing a system for automated control of rotation axes, collimator and laser adjustment for a medical linear accelerator.
abstract: Mechanical stability and precise adjustment of rotation axes, collimator and room lasers are essential for the success of radiotherapy and particularly stereotactic radiosurgery with a linear accelerator. Quality assurance procedures, at present mainly based on visual tests and radiographic film evaluations, should desirably be little time consuming and highly accurate. We present a method based on segmentation and analysis of digital images acquired with an electronic portal imaging device (EPID) that meets these objectives. The method can be employed for routine quality assurance with a square field formed by the built-in collimator jaws as well as with a circular field using an external drill hole collimator. A number of tests, performed to evaluate accuracy and reproducibility of the algorithm, yielded very satisfying results. Studies performed over a period of 18 months prove the applicability of the inspected accelerator for stereotactic radiosurgery.
authors.affiliation: Department of Radiation Oncology, Karl-Franzens University Medical School, Auenbruggerplatz 32, 8036-Graz, Austria. Peter.Winkler@uni-graz.at
authors.forename: Peter
authors.initials: P
authors.lastname: Winkler
authors.forename: Helmar
authors.initials: H
authors.lastname: Bergmann
authors.forename: Georg
authors.initials: G
authors.lastname: Stuecklschweiger
authors.forename: Helmuth
authors.initials: H
authors.lastname: Guss
mesh_terms: D000465:Algorithms; D002138:Calibration; D004867:Equipment Design; D019544:Equipment Failure Analysis; D005246:Feedback; D007834:Lasers; D010315:Particle Accelerators / Q000295:instrumentation* / Q000592:standards; D011786:Quality Control; D011856:Radiographic Image Enhancement / Q000295:instrumentation / Q000379:methods; D011874:Radiometry / Q000295:instrumentation* / Q000379:methods*; D011878:Radiotherapy / Q000295:instrumentation* / Q000379:methods / Q000592:standards; D011879:Radiotherapy Dosage; D011880:Radiotherapy Planning, Computer-Assisted / Q000295:instrumentation / Q000379:methods*; D015203:Reproducibility of Results; D012371:Robotics / Q000379:methods*; D012399:Rotation; D012680:Sensitivity and Specificity