Model 004
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CT Simulator for Bone Mineral Analysis Model 004 SIMPLE • EFFECTIVE • ACCURATE PRODUCT GUIDE 2428 Almeda Avenue Suite 316 • Norfolk, Virginia 23513 • USA • Tel: 757-855-2765 WWW.CIRSINC.COM

Background Since the advent of whole-body Computed Tomography (CT) scanners in the late 1970’s, considerable research effort has been expended to develop a method of density measurement. The power of the CT scanner could be applied to studies of bone demineralization, particularly in the lumbar region of the vertebral column where the earliest changes of osteoporosis or diffuse bone loss occur. It became apparent to early researchers that several problems of scanner variability needed to be overcome before quantitative studies could be generally performed with high reliability. Quantitative...

The CIRS Approach to Quantitative CT PRINCIPLES OF DESIGN The CIRS CT Model 004 Simulator for Bone Mineral Analysis is designed to take into account all the known sources of variance affecting the measurement of density in the vertebral area by simulating the average patient’s anatomy in terms of shape and density by using materials essentially equivalent to human tissues as far as X-ray interactions are concerned, including age-related variations in vertebral composition. • Accurately simulates the size, shape and CT density of human tissue The design of the system permits reduction of all...

The CIRS Model 004 CT Simulator BASIC SECTION Our manufacturing methods insure that each part of the phantom is carefully controlled so that each finished phantom is identical to the next. This is why human bone, the quality and consistency of which cannot be controlled, have not been used. The phantom represents an average section of the anatomy (2nd to 4th lumbar region) that has been shown to present early demineralization in patients with osteoporosis. The phantom, constructed of specially formulated materials, interacts with X-Radiation in a manner identical to the human body (within...

Comparison with Other BMD Measurements HA vs. K2HPO4 late the effect of marrow fat build-up in performing CT analysis of vertebral bone mineral content. The CIRS simulator provides Bone Mineral Content (BMC) values in mg/cc of calcium hydroxyapatites (HA) that approximate ash weight values. Dual energy CT evaluation of vertebral BMC has validated the CIRS simulation system values. For scanner operators having dual energy capability, the CIRS Simulator provides a system calibration capability, but simulation of each patient is not required. At the range of normal vertebral body ash weight...

Comparing BMD Values With a Normal Population The BMD measured for a patient is compared with age- and sex- matched controls as well as with sex-matched young healthy controls. The values are then expressed as percentiles or standard deviation scores, called Z- or T-scores. The T-score is a measure of the difference between the patient’s BMD and the mean BMD of young normals. The Tscore, in SD values, is calculated as: The Z-score is a measure of the difference between the patient’s BMD and the mean BMD of age- and sex-matched peers. The Z-score, in SD values, is calculated as: Z-score(SD)...

Qualification of Slice Thickness IMAGE EVALUATION 1 MM BEAM FIGURE 1 The optimum technique for CT analysis of vertebral bone density with the CIRS Mode 004 CT Simulator for Bone Mineral Analysis will vary with each type of scanner. As a rule, 5 mm or 10 mm slice section available on the scanner should be used for vertebral Bone Mineral Content (BMC) analysis. Remember, quantitative CT analysis requires accuracy of slice thickness. (When isolating trabecular bone for analysis by CT, you want to ensure that cortical bone is not included in the slice selected.) SLICE THICKNESS AND BEAM...

Qualification of Slice Thickness IMAGE EVALUATION 3 MM BEAM FIGURE 2 0.0 deg Rotation Beam Profile Image Plane Beam Profile Image Plane IMAGE EVALUATION 1 MM BEAM FIGURE 3 2.0 deg-CW Rotation Beam Profile Image Plane Beam Profile FIGURE 2A Shows a 3 mm slice through origin and demonstrates alignment and symmetry of the image and beam alignment along the X / Y axis. Note the increase in image elements shown on the image plane with the increased beam width. Image demonstrates proper alignment. The 3 full dark bars each represent 1 mm slice. The 2 full length lighter bars (20%) represent...

Scan Protocols ALGORITHM OF RECONSTRUCTION On some scanners there is only one available algorithm of reconstruction for body applications and there is no other option but to use the algorithm provided. Bone marrow fat increases with age, and this increased bone marrow fat affects the CT value reading. Theoretically, a person could maintain the same level of bone mineral content over a period of years and yet have progressively lower CT values due solely to the increase in bone marrow fat and the way in which this increase affects the machine’s reading. This effect has been described by a...

Scanning and Data Acquisition Procedure 1. Place patient on table with arms over head. Obtain a lateral scout view (scanography or pilot view) to localize third lumbar vertebral area. Set up simulator on support board, properly sized and with vertebral insert for 50 mg/cc (age 45) of mineral content in place (be sure to attach velcro backed “mark- er” to support board so that retained images will reflect which insert was used). Position with laser light in the center of the simulator. (Ensure the simulator is vertical to the table use a sandbag on the foot of the stand if necessary). Scan...

CIRSCALC® Software CIRSCALC is PC software for use with the CIRS Model 004 Lumbar Reference Simulator. The program performs data analysis calculations and produces printed reports. ADDING A NEW PATIENT FOLDER 1. Select the Patient’s Exam Folder by selecting Patient Exam under the File Menu. The CD contains both “New Installation” and “update” for previous users of Version 6.01. For questions pertaining to this program or the Bone Mineral Measurement System, or to obtain the latest version of CIRSCALC, please contact CIRS. 2. Click the ADD button (hint: move the mouse pointer slowly over the...