Measurement of CT scanner dose profiles in a filmless department.
The measurement of the FWHM of the slice thickness radiation dose profile of a CT scanner using a prototype low sensitivity CR imaging plate has been investigated, as an alternative to the traditional method using envelope-packed industrial film. Using a standard Agfa clinical CR system to acquire the image, the FWHM of the dose profile can be accurately measured using readily available Public Domain software. An Agfa 18 x 24 cm CR cassette gives a pixel pitch of 113.5 microm, but with interpolation, the measurement accuracy can be less than 1 pixel. For a nominal 10 mm collimation, 15 successive measurements of the FWHM using CR gave an average width of 10.00 mm with a standard deviation of 0.02 mm. This may be compared with 4 successive measurements using film and a dual exposure technique to define the optical density at half peak height, yielding an average width of 9.98 mm with a SD of 0.03 mm. This prototype NDT plate is not a commercial product, but a radiotherapy plate with a similar sensitivity is available commercially and should give similar results.
Thomson
F J
FJ
Radiology Department, Auckland City Hospital, Auckland, New Zealand. fthomson@adhb.govt.nz
D001315:Australia; D004867:Equipment Design; D019544:Equipment Failure Analysis / Q000295:instrumentation* / Q000379:methods*; D011785:Quality Assurance, Health Care / Q000379:methods*; D011829:Radiation Dosage; D011835:Radiation Protection / Q000295:instrumentation* / Q000379:methods; D011872:Radiology Department, Hospital; D011874:Radiometry / Q000295:instrumentation* / Q000379:methods; D014057:Tomography, X-Ray Computed / Q000295:instrumentation*