Estimate of external background radiation interference on a tomography scanner

Roberson, G P ; Logan, C M

Lawrence Livermore National Laboratory

关键词: Computerized Tomography;    Statistics;    Geometry;    36 Materials Science;    Background Radiation;   

DOI  :  10.2172/15003405
RP-ID  :  UCRL-ID-140176
RP-ID  :  W-7405-ENG-48
RP-ID  :  15003405

美国|英语

来源: UNT Digital Library

【 摘 要 】

We have estimated interference from external background radiation for a computed tomography (CT) scanner. Our intention is to estimate the interference that would be expected for the high-resolution SkyScan 1072 desk-top x-ray microtomography system. The SkyScan system uses a Microfocus x-ray source capable of a 10-{micro}m focal spot at a maximum current of 0.1 mA and a maximum energy of 130 kVp. All predictions made in this report assume using the x-ray source at the smallest spot size, maximum energy, and operating at the maximum current. Some of the systems basic geometry that is used for these estimates are: (1) Source-to-detector distance: 250 mm, (2) Minimum object-to-detector distance: 40 mm, and (3) Maximum object-to-detector distance: 230 mm. This is a first-order, rough estimate of the quantity of interference expected at the system detector caused by background radiation. The amount of interference is expressed by using the ratio of exposure expected at the detector of the CT system. The exposure values for the SkyScan system are determined by scaling the measured values of an x-ray source and the background radiation adjusting for the difference in source-to-detector distance and current. The x-ray source that was used for these measurements was not the SkyScan Microfocus x-ray tube. Measurements were made using an x-ray source that was operated at the same applied voltage but higher current for better statistics.