CT AutoQA Lite Software sold by Supertech

IRIQALLC CT AutoQA Lite is an updated Windows program to the original PC/AutoQA for CT. This update provides expanded image processing capacity for up to 96 images in a data set with a comprehensive trend analysis feature.

Processing Features

CT AutoQA Lite can be configured with various vendor phantoms including the Catphan 402, 424, 440, 500 and 600 models, ACR and GE [1,2]. CT AutoQA Lite is DICOM3.0 compatible, a DICOM Storage Provider (SCP) Application license is provided. CT AutoQA Lite provides the same analysis function as the original DOS version;

Pixel Size – test verifies the expected pixel size based on the display field of view and the reconstruction matrix size from the measured set of four calibration pins positioned at a known physical location as specified in the Catphan section CTP401.
CT Linearity (Sensitometry) – Mean CT values are calculated for each reference material in the phantom test section. The measured CT numbers for test materials are fit to the linear attenuation coefficients using a linear least squares for energies from 40 to 100 keV. The variance representing the lowest variance was designated as the scanner’s effective energy. The linear attenuation coefficients for this effective energy are used to determine the contrast scale from the calculated linearity slope.[3].
Slice Thickness – is determined from the average full-width at half-maximum (FWHM) of the CT number profile for each wire ramp. The expected slice width is compared with all four measured ramps values. A trigonometric conversion is calculated based on the know ramp angle to yield the slice width. This test provides information on the position of the phantom and the vertical and horizontal tilt values. A rotation of the phantom about an axis perpendicular to the ramps is also computed. Since there are two pairs of ramps orientated along the orthogonal directions, phantom rotations about both the vertical and horizontal axes can be estimated [4].
Localizer and Table Incrementation Accuracy – can be evaluated from the slice width section when the ramps are paired at opposing angles. The slice width test outputs a parameter called Table Position Offset, which an offset in the z-axis relative to the center of the opposing wire (or test section). Verification of the scanner table incrementation accuracy can be checked by incrementing the table by 30 mm and then returning the table to the starting position and scanning the slice width module. The reported table position offset values should be the same.
Spatial Resolution (MTF) – The modulation transfer function (MTF) is calculated from the discrete Fourier Transform of the average vertical and horizontal LSF’s of the point spread function from the bead or wire test section. The program reports the 50%, 10% and 2% MTF cutoff values [5].
Noise and Mean CT Number – is calculated from several regions of interest (ROI) positioned over a water/uniformity phantom section. The number, size and location of these ROI’s are variable, but typically five are defined: one at the phantom center and the other four along the axes at the same radius covering a 15 x 15 pixel area.
Uniformity – Vertical and horizontal profiles 10 pixel wide are generated and averaged through the phantom’s center. The fractional uniformity of the profile is calculated as the percentage of the pixels within an acceptable range determined by + 2 times the central noise or + 10H, whichever is smaller.

Contrast Detail (Low Contrast Resolution) – Theoretical Contrast-Detail data is calculated based on the measured noise of the water/uniformity test section. Note: low contrast modules (CTP263 and CTP515) are not used in this measurement. This represents a conservative estimate of the minimum contrast level required such that a cylindrical object of a given diameter should be detected [6] .

RESULT FEATURES
CT AutoQA Lite provides two database options for storage of test results. ‘Monitor Database’, is the first database option designated for constancy/monitoring and is linked to the Trend Analysis function. The ‘Service Database’ is the second data base option and is designed for more extensive service and/or acceptance testing data sets. If neither of these two options is appropriate, the user can select the option to not store results but only view results.

The basic display of results is provided as a scrolling window, with a print Test Results button function. The Trend Analysis feature (not available with the original DOS version) is available for Noise/Mean CT number, slice width, spatial resolution (MTF), and CT linearity measurements. The Trend Analysis function is linked to the monitor database files and follows guidelines for CT constancy testing established by the International Electrotechnical Commission (IEC) 61223-2-6 – v(Constancy tests - X-ray equipment for computed tomography). 2006

Software Information

Equipment Requirements:

PC running Windows XP/VISTA Operating System.

CDROM drive

CT-PC network connection using TCP/IP protocol & Network Adapter

Recommended Minimum System Requirements

16 HZ CPU

512MB RAM

Current Release: Version 2.35

References

Goodenough DJ, Weaver KE, Davis, DO. Development of a Phantom for Evaluation and Assurance of Image Quality. Optical Engineering, 16:52-65, Jan/Feb 1976.
Goodenough DJ, Levy JR, Kasales C. Development of phantom for Spiral CT. Computerized Medical Imaging and Graphics, 22: 247-255 1998.
Kriz RJ, Strauss KJ, An Investigation of computed tomography (CT) Linearity. Medical Imaging and Instrumentation, SPIE Vol. 555, 195-204, 1985.
Atkins FB, Goodenough DJ, Levy JR. A New Method to Test CT Scan Plane Angulation and Rotation Relative to a Test Phantom. Radiology Vol. 209 (P), Pg 285, 1998.
Rossman K. Point Spread Function, Line Spread Function and Modulation Transfer Function : Tools for the Study of Imaging Systems. Radiology 93:257-72, 1969.
Cohen G, DiBianca FA, The Use of Contrast-Detail-Dose Evaluation of Image Quality in a Computed Tomographic Scanner. Journal of Computed Assisted Tomography 3(2):189-195, April 1979.

Note: This product works well with Cat Phan

Contact Supertech ^{^{^®}} for complete product brochures.

AutoQA Lite Software

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Software Information