Verification of CT number to density conversion for a simulator-T attachment.
The calculation and verification of a CT number to density conversion table for a simulator-CT attachment known as Scanvision, which provides CT images for radiotherapy treatment planning, is presented. While the linear fit for CT-number-to-density is similar to most conventional doughnut gantry CT scanners, an offset of approximately 178 Hounsfield units was found for air using a polyethylene normalisation, and approximately 262 for air using air normalisation. The offset continues for other low-density samples. Results show that the simulator-CT reproducibly measures CT numbers. However a separate calibration line needs to be entered into the radiotherapy planning computer to ensure accurate CT-number-to-density. conversion.
Chapman
A
A
Physics Department, University of Wollongong NSW, Australia.
Butson
M
M
Quach
K
K
Rozenfeld
A
A
Metcalfe
P
P
D006801:Humans; D019047:Phantoms, Imaging; D011878:Radiotherapy / Q000295:instrumentation* / Q000379:methods*; D011879:Radiotherapy Dosage; D011880:Radiotherapy Planning, Computer-Assisted / Q000295:instrumentation / Q000379:methods; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity; D014057:Tomography, X-Ray Computed / Q000295:instrumentation* / Q000379:methods*