title: Measurement of background signals due to scattered and off-focal radiation on CT scanners.
abstract: The magnitude of scattered and off-focal radiation in relation to the primary radiation has been measured for 4 commercial CT scanners of third generation (only rotation). The measurement has been done by placing a lead beam stop in front of a scattering phantom as well as without a phantom and registering the detector signal behind and outside the lead beam stop. The off-focal radiation has been found to be very similar in magnitude for 3 of the scanners compared, while the scattered radiation from the phantom was found to vary with parameters like distance between phantom and detector, grid in front of the detector and self collimation of the detector.
mesh_terms: D001417:Background Radiation; D008961:Models, Structural; D012542:Scattering, Radiation; D014057:Tomography, X-Ray Computed / Q000295:instrumentation* / Q000379:methods