Technical Note: Confirming the prescribed angle of CT localizer radiographs and c-arm projection acquisitions.

Med Phys 2016 Feb;43(2):865-9

Department of Human Oncology, University of Wisconsin-Madison, Madison, Wisconsin 53705.

Purpose: Accurate CT radiograph angle is not usually important in diagnostic CT. However, there are applications in radiation oncology and interventional radiology in which the orientation of the x-ray source and detector with respect to the patient is clinically important. The authors present a method for measuring the accuracy of the tube/detector assembly with respect to the prescribed tube/detector position for CT localizer, fluoroscopic, and general radiograph imaging using diagnostic, mobile, and c-arm based CT systems.

Methods: A mathematical expression relating the x-ray projection of two metal BBs is related to gantry angle. Measurement of the BBs at a prescribed gantry (i.e., c-arm) angle can be obtained and using this relation the prescribed versus actual gantry angle compared. No special service mode or proprietary information is required, only access to projection images is required. Projection images are available in CT via CT localizer radiographs and in the interventional setting via fluorography.

Results: The technique was demonstrated on two systems, a mobile CT scanner and a diagnostic CT scanner. The results confirmed a known issue with the mobile scanner and accurately described the CT localizer angle of the diagnostic system tested.

Conclusions: This method can be used to quantify gantry angle, which is important when projection images are used for procedure guidance, such as in brachytherapy and interventional radiology applications.

Download full-text PDF

Source
http://dx.doi.org/10.1118/1.4940124DOI Listing
February 2016
36 Reads

Publication Analysis

Top Keywords

projection images
12
gantry angle
12
angle diagnostic
8
interventional radiology
8
mobile scanner
8
localizer radiographs
8
angle
7
projection
5
x-ray projection
4
scanner accurately
4
confirmed issue
4
c-arm based
4
images localizer
4
based systemsmethods
4
systemsmethods mathematical
4
issue mobile
4
expression relating
4
mathematical expression
4
relating x-ray
4
accurately described
4

Similar Publications