Biomedical subjects

C H McCollough

Publications and source records attributed to C H McCollough.

At least 19 recordsLinked to original sources

PubMed2005

A Monte Carlo based method to estimate radiation dose from multidetector CT (MDCT): cylindrical and anthropomorphic phantoms.

The purpose of this work was to extend the verification of Monte Carlo based methods for estimating radiation dose in computed tomography (CT) exams beyond a single CT scanner to a multidetector CT (MDCT) scanner, and from cylindrical CTDI phantom measurements to both cylindrical and physical anthropomorphic phantoms. Both cylindrical and physical anthropomorphic phantoms were scanned on an MDCT under the specified conditions. A pencil ionization chamber was used to record exposure for the cylindrical phantom, while MOSFET (metal oxide semiconductor field effect transistor) detectors were used to record exposure at the surface of the anthropomorphic phantom. Reference measurements were made in air at isocentre using the pencil ionization chamber under the specified conditions. Detailed Monte Carlo models were developed for the MDCT scanner to describe the x-ray source (spectra, bowtie filter, etc) and geometry factors (distance from focal spot to isocentre, source movement due to axial or helical scanning, etc). Models for the cylindrical (CTDI) phantoms were available from the previous work. For the anthropomorphic phantom, CT image data were used to create a detailed voxelized model of the phantom's geometry. Anthropomorphic phantom material compositions were provided by the manufacturer. A simulation of the physical scan was performed using the mathematical models of the scanner, phantom and specified scan parameters. Tallies were recorded at specific voxel locations corresponding to the MOSFET physical measurements. Simulations of air scans were performed to obtain normalization factors to convert results to absolute dose values. For the CTDI body (32 cm) phantom, measurements and simulation results agreed to within 3.5% across all conditions. For the anthropomorphic phantom, measured surface dose values from a contiguous axial scan showed significant variation and ranged from 8 mGy/100 mAs to 16 mGy/100 mAs. Results from helical scans of overlapping pitch (0.9375) and extended pitch (1.375) were also obtained. Comparisons between the MOSFET measurements and the absolute dose value derived from the Monte Carlo simulations demonstrate agreement in terms of absolute dose values as well as the spatially varying characteristics. This work demonstrates the ability to extend models from a single detector scanner using cylindrical phantoms to an MDCT scanner using both cylindrical and anthropomorphic phantoms. Future work will be extended to voxelized patient models of different sizes and to other MDCT scanners.

Body Burden↗

PubMed2005

The calibration of experimental self-developing Gafchromic HXR film for the measurement of radiation dose in computed tomography.

A prototype, self-developing Gafchromic HXR film has sensitivity an order of magnitude larger than that of the commercially available Gafchromic XR film used in interventional radiological applications. The higher sensitivity of the HXR film allows the possibility of acquisition of high-resolution calibrated dose profiles within the diagnostic range of exposure levels, below 10 R (87.7 mGy). We employed a commercially available, optical flatbed scanner for digitization of the film and image analysis software to determine the response of the HXR films to ionizing radiation. Spatial uniformity and temporal repeatability of the flatbed scanner were determined and used in optimization of the digitization protocol. The HXR film postexposure density growth and sensitivity to ambient light were determined using multiple scans of two simultaneously exposed sheets, one stored in light-tight conditions and the other continuously illuminated with white light. A calibrated step wedge of the HXR film was obtained by simultaneous irradiation of a portion of a film strip and a calibrated ionization chamber using a radiographic x-ray tube with beam characteristics matched to a typical CT scanner (8 mm Al HVL, 120 kVp). Repeated digitization of the calibration film was used to determine the precision of the film response measurements. The precision, as measured by the standard deviation of multiple measurements, was better than 1% over the full dynamic range of film response. This precision was measured using exposures ranging from 0.5 to 12 R (4.4 to 105.3 mGy). This exposure range is highly relevant to x-ray computed tomography. Preliminary radiation dose profiles demonstrate the utility of this technique.

Abdomen↗

PubMed2005

Image reconstruction and image quality evaluation for a 64-slice CT scanner with z-flying focal spot.

We present a theoretical overview and a performance evaluation of a novel z-sampling technique for multidetector row CT (MDCT), relying on a periodic motion of the focal spot in the longitudinal direction (z-flying focal spot) to double the number of simultaneously acquired slices. The z-flying focal spot technique has been implemented in a recently introduced MDCT scanner. Using 32 x 0.6 mm collimation, this scanner acquires 64 overlapping 0.6 mm slices per rotation in its spiral (helical) mode of operation, with the goal of improved longitudinal resolution and reduction of spiral artifacts. The longitudinal sampling distance at isocenter is 0.3 mm. We discuss in detail the impact of the z-flying focal spot technique on image reconstruction. We present measurements of spiral slice sensitivity profiles (SSPs) and of longitudinal resolution, both in the isocenter and off-center. We evaluate the pitch dependence of the image noise measured in a centered 20 cm water phantom. To investigate spiral image quality we present images of an anthropomorphic thorax phantom and patient scans. The full width at half maximum (FWHM) of the spiral SSPs shows only minor variations as a function of the pitch, measured values differ by less than 0.15 mm from the nominal values 0.6, 0.75, 1, 1.5, and 2 mm. The measured FWHM of the smallest slice ranges between 0.66 and 0.68 mm at isocenter, except for pitch 0.55 (0.72 mm). In a centered z-resolution phantom, bar patterns up to 15 lp/cm can be visualized independent of the pitch, corresponding to 0.33 mm longitudinal resolution. 100 mm off-center, bar patterns up to 14 lp/cm are visible, corresponding to an object size of 0.36 mm that can be resolved in the z direction. Image noise for constant effective mAs is almost independent of the pitch. Measured values show a variation of less than 7% as a function of the pitch, which demonstrates correct utilization of the applied radiation dose at any pitch. The product of image noise and square root of the slice width (FWHM of the respective SSP) is the same constant for all slices except 0.6 mm. For the thinnest slice, relative image noise is increased by 17%. Spiral windmill-type artifacts are effectively suppressed with the z-flying focal spot technique, which has the potential to maintain a low artifact level up to pitch 1.5, in this way increasing the maximum volume coverage speed that can be clinically used.

Equipment Design↗

PubMed2001

Update on patient radiation doses at a large tertiary care medical center.

Radiation procedures in diagnostic radiology and nuclear medicine examinations, especially at referral centers, contribute a significant proportion to population dose; hence, there is a presumed detriment. Knowledge of the magnitude of dose from each type of exam is helpful in determining where to implement dose reduction efforts. Additionally, new records of dose data facilitate comparisons with past measurements. In this paper, updated patient exam dose data (frequency and effective dose equivalent) are provided for a large, comprehensive, tertiary care medical center that served more than 340,000 patients in 1997. Patient billing code data were used to study 31 different types of diagnostic exams encompassed in five major categories (angiography, fluoroscopy, radiography, nuclear medicine, and computerized tomography). Organ doses for each radiographic and nuclear medicine exam were estimated using published Monte Carlo conversion factors and appropriate exposure values. Estimates of organ doses were utilized to compute effective dose equivalent (EDE) per ICRP 26 and collective effective dose equivalent. Mean effective dose equivalent was also calculated for each exam category. Total collective effective dose equivalent had decreased from 1988 (2,030 person-Sv) to 1997 (1,817 person-Sv). The largest contributors to collective effective dose equivalent were angiography (768 person-Sv), computerized tomography (447 person-Sv), and nuclear medicine (355 person-Sv). Radiography (150 person-Sv) and fluoroscopy (97 person-Sv) contributed the least to collective effective dose equivalent. Mean effective dose equivalent contributions remained the same, with angiography accounting for the highest component, followed by nuclear medicine, computerized tomography, fluoroscopy, and radiography, respectively. Effective dose equivalent, collective effective dose equivalent, and mean effective dose equivalent values were calculated and tabulated in five major categories. These data provide updated information as to trends in exam and; collective dose from 31 common types of radiologic exams performed at a large medical center, which can be used as an up to date baseline for analyses of trends in U.S. radiation doses due to medical imaging procedures. Although minor changes were observed in comparing the mean effective dose equivalent data to those of a previous study, substantial differences were evident in the collective effective dose equivalent data. This was due primarily to variations in the number of patients examined and changes in technology and practice.

Angiography↗

PubMed2001

Image quality and dose comparison among screen-film, computed, and CT scanned projection radiography: applications to CT urography.

PURPOSE: To evaluate image quality and dose for abdominal imaging techniques that could be used as part of a computed tomographic (CT) urographic examination: screen-film (S-F) radiography or computed radiography (CR), performed with moving and stationary grids, and CT scanned projection radiography (CT SPR). MATERIALS AND METHODS: An image quality phantom underwent imaging with moving and stationary grids with both a clinical S-F combination and CR plate. CT SPR was performed with six CT scanners at various milliampere second and kilovolt peak settings. Entrance skin exposure (ESE); spatial, contrast, and temporal resolutions; geometric accuracy; and artifacts were assessed. RESULTS: S-F or CR images, with either grid, provided image quality equivalent to that with the clinical standard, S-F with a moving grid. ESE values for both S-F and CR were 435 mR (112.2 microC/kg [1 mR = 0.258 microC/kg]) with a moving grid and 226 mR (58.3 microC/kg) with a stationary grid. All CT SPR images provided inferior spatial resolution compared with S-F or CR images. High-contrast objects generated substantial artifacts on CT SPR images. Compared with S-F, CR and CT SPR provided improved resolution of small low-contrast objects. The contrast between iodine and soft-tissue-mimicking structures on CT SPR images acquired at 80 kVp was twice that at 120 kVp. CT SPR images with acceptable noise levels required a midline ESE value of approximately 300 mR (77.4 microC/kg) at 80 kVp. CONCLUSION: S-F and CR provided better spatial resolution than did CT SPR. However, CT SPR provided improved low-contrast resolution compared with S-F, at exposures comparable to those used for S-F or CR.

Equipment Design↗

PubMed2001

CT colonography: single- versus multi-detector row imaging.

PURPOSE: To compare respiratory artifacts, colonic distention, and polyp detection at computed tomographic (CT) colonography by using single- and multi-detector row helical CT systems. MATERIALS AND METHODS: A total of 237 consecutive patients received subcutaneously administered glucagon and underwent prone and supine CT colonography with single-detector row CT (n = 77) and multi-detector row CT (n = 160), followed by colonoscopy. Examination results were graded for colonic distention, respiratory artifacts, and polyp depiction by two radiologists working independently. RESULTS: Suboptimal colonic distention was significantly more common with single-detector row CT and was present in at least one segment in 52% (40 of 77 patients) of examinations versus only 19% (30 of 160 patients) with multi-detector row CT (P <.001). Mild respiratory artifacts were present in 61% (47 of 77 patients) of single-detector row CT examinations versus only 16% (26 of 160 patients) of multi-detector row CT examinations (P <.001). Depiction of polyps larger than 10 mm was 89% (eight of nine polyps) for single-detector row CT and 80% (eight of 10 polyps) for multi-detector row CT (P >.05). CONCLUSION: CT colonography performed with multi-detector row CT significantly improved the demonstration of colonic distention and depicted fewer respiratory artifacts compared with single-detector row CT. No significant differences in the depiction of polyps larger than 10 mm were demonstrated between single- and multi-detector row CT for a small number of polyps. Studies with a larger prevalence of clinically important polyps are needed for further evaluation of differences in polyp detection.

Adult↗

PubMed2000

Measurement of half-value layer in x-ray CT: a comparison of two noninvasive techniques.

The purpose of this paper is to determine the accuracy and reproducibility of two noninvasive methods of measuring half-value layer (HVL), ring and localization, compared with an invasive technique (suspending tube rotation). The ring method uses concentric aluminum rings about a CTDI ionization chamber at isocenter. Data were acquired using axial CT protocols (rotating x-ray tube, stationary patient table). The localization technique uses square aluminum sheets secured to the gantry shroud to filter the radiation beam, and a CTDI chamber suspended externally at isocenter. Data were acquired using localization image protocols (stationary x-ray tube, moving patient table). The invasive technique was similar to the localization technique except that the ion chamber was placed on the patient table and the tube rotation disabled using service software. Data for all techniques were collected on the same CT system. Independent data sets were collected to determine reproducibility. Sensitivity to ionization chamber lateral displacement from isocenter was investigated. Measured HVLs (mm aluminum, mean+/-std, n=4) were 7.19+/-0.03 (ring); 7.17+/-0.04 (localization); and 7.24+/-0.02 (service mode), which were not significantly different (p = 0.05). Displacing the chamber from isocenter changes the HVL, depending on the bow-tie filter, by as much as 5 mm aluminum. Aluminum filter to ion chamber distances of 25-35 cm provided accurate results. Both noninvasive techniques were accurate and reproducible at isocenter. However, the measured HVL was dependent upon the bow-tie filter and the lateral displacement of the ionization chamber with respect to isocenter. Greater than 2 cm off of isocenter, the ring technique did not provide accurate HVL measurements.

Aluminum↗

PubMed2000

Calculation of effective dose.

The concept of "effective dose" was introduced in 1975 to provide a mechanism for assessing the radiation detriment from partial body irradiations in terms of data derived from whole body irradiations. The effective dose is the mean absorbed dose from a uniform whole-body irradiation that results in the same total radiation detriment as from the nonuniform, partial-body irradiation in question. The effective dose is calculated as the weighted average of the mean absorbed dose to the various body organs and tissues, where the weighting factor is the radiation detriment for a given organ (from a whole-body irradiation) as a fraction of the total radiation detriment. In this review, effective dose equivalent and effective dose, as established by the International Commission on Radiological Protection in 1977 and 1990, respectively, are defined and various methods of calculating these quantities are presented for radionuclides, radiography, fluoroscopy, computed tomography and mammography. In order to calculate either quantity, it is first necessary to estimate the radiation dose to individual organs. One common method of determining organ doses is through Monte Carlo simulations of photon interactions within a simplified mathematical model of the human body. Several groups have performed these calculations and published their results in the form of data tables of organ dose per unit activity or exposure. These data tables are specified according to particular examination parameters, such as radiopharmaceutical, x-ray projection, x-ray beam energy spectra or patient size. Sources of these organ dose conversion coefficients are presented and differences between them are examined. The estimates of effective dose equivalent or effective dose calculated using these data, although not intended to describe the dose to an individual, can be used as a relative measure of stochastic radiation detriment. The calculated values, in units of sievert (or rem), indicate the amount of whole-body irradiation that would yield the equivalent radiation detriment as the exam in question. In this manner, the detriment associated with partial or organ-specific irradiations, as are common in diagnostic radiology, can be assessed.

Female↗

PubMed2000

Lung nodules: dual-kilovolt peak analysis with CT--multicenter study.

PURPOSE: To test the following hypothesis: The greater the increase in the mean computed tomographic (CT) number of a radiologically indeterminate lung nodule from the CT number on a 140-kVp CT image to that on an 80-kVp CT image, the more likely the nodule is benign (ie, contains calcium). MATERIALS AND METHODS: Two hundred forty indeterminate lung nodules were prospectively studied at four institutions: Mayo Clinic Scottsdale, Ariz (n = 160); Mayo Clinic Rochester, Minn (n = 50); Shiga Health Insurance Hospital, Otsu, Japan (n = 25); and Duke University Medical Center, Durham, NC (n = 5). Of the 240 nodules, 157 met the entrance criteria for this study and had a diagnosis. All nodules included were solid, 5-40-mm diameter, relatively spherical, homogeneous, and without visible evidence of calcification or fat. Each nodule was evaluated by using 3-mm-collimation, nonenhanced CT scans with both 140- and 80-kVp x-ray beams. RESULTS: There were 86 (55%) benign and 71 (45%) malignant nodules. The median increase in the nodule mean CT number from the CT number on 140-kVp images to that on 80-kVp images was 2 HU for benign nodules and 3 HU for malignant nodules. This difference was not statistically significant. The area under the receiver operating characteristic curve was 0.505. CONCLUSION: Dual-kilovolt peak analysis with current CT technology does not appear to be helpful in the identification of benign lung nodules.

Adult↗

PubMed1999

Experimental determination of section sensitivity profiles and image noise in electron beam computed tomography.

To determine the effect of continuous-volume scanning (CVS) on z-axis resolution, section sensitivity profiles were measured on an electron beam computed tomography (CT) scanner and compared with those obtained using the step-volume scanning (SVS) mode. A steel bead was imaged using different scan parameters, and the mean CT number over the bead was plotted against the z-axis position to determine section sensitivity profiles. From these profiles, full width at half maximum (FWHM), full width at tenth maximum (FWTM), and full width at tenth area (FWTA) were calculated. A uniform water phantom was imaged to measure noise. To determine the visual significance of changes in the section sensitivity profile, a section thickness and contiguity phantom was imaged. All section sensitivity profiles measured had an FWHM value within 0.5 mm of the nominal scan width. The FWTM and FWTA values increased with the CVS mode compared with the SVS mode. This broadening of the section sensitivity profiles was most significant with larger collimator widths. However, use of smaller collimator widths increased image noise. When all other parameters remained constant, increasing the exposure time to reduce image noise did not affect the section sensitivity profile. The CVS mode produced wider section sensitivity profiles than the SVS mode. This effect was minimized when the smallest collimator width was used, but at the expense of increased image noise.

Electrons↗

PubMed1999

Performance evaluation of a multi-slice CT system.

Our purpose in this study was to characterize the performance of a recently introduced multi-slice CT scanner (LightSpeed QX/i, Version 1.0, General Electric Medical Systems) in comparison to a single-slice scanner from the same manufacturer (HiSpeed CT/i, Version 4.0). To facilitate this comparison, a refined definition of pitch is introduced which accommodates multi-slice CT systems, yet maintains the existing relationships between pitch, patient dose, and image quality. The following performance parameters were assessed: radiation and slice sensitivity profiles, low-contrast and limiting spatial resolution, image uniformity and noise, CT number and geometric accuracy, and dose. The multi-slice system was tested in axial (1, 2, or 4 images per gantry rotation) and HQ (Pitch = 0.75) and HS (Pitch = 1.5) helical modes. Axial and helical acquisition speed and limiting spatial resolution (0.8-s exposure) were improved on the multi-slice system. Slice sensitivity profiles, image noise, CT number accuracy and uniformity, and low-contrast resolution were similar. In some HS-helical modes, helical artifacts and geometric distortion were more pronounced with a different appearance. Radiation slice profiles and doses were larger on the multi-slice system at all scan widths. For a typical abdomen and pelvis exam, the central and surface body doses for 5-mm helical scans were higher on the multi-slice system by approximately 50%. The increase in surface CTDI values (with respect to the single-slice system) was greatest for the 4 x 1.25-mm detector configuration (190% for head, 240% for body) and least for the 4 x 5-mm configuration (53% for head, 76% for body). Preliminary testing of version 1.1 software demonstrated reduced doses on the multi-slice scanner, where the increase in body surface CTDI values (with respect to the single-slice system) was 105% for the 4 x 1.25-mm detector configuration and 10% for the 4 x 5-mm configuration. In summary, the axial and HQ-helical modes of the multi-slice system provided excellent image quality and a substantial reduction in exam time and tube loading, although at varying degrees of increased dose relative to the single-slice scanner.

Acrylic Resins↗

PubMed1996

Detection of colorectal polyps by computed tomographic colography: feasibility of a novel technique.

BACKGROUND & AIMS: Computed tomographic colography (CTC) represents a novel technique for colorectal polyp detection. A prospective study was undertaken to determine the optimal CTC scanning parameters based on an artificial colon model and to assess the feasibility of CTC to detect clinically significant colorectal polyps. METHODS: A colon model was scanned by helical computed tomography at multiple parameters. Reformatted two-dimensional and three-dimensional images were then graded for polyp detection and image quality. Subsequently, 10 patients with known colon polyps underwent CTC immediately before colonoscopy. The number of polyps detected by two radiologists using CTC were compared with colonoscopy results that served as the gold standard. RESULTS: The optimal scanning parameters in the colon model were 5-mm collimation, 5 mm/s table speed, and 1-mm reconstruction interval. Ten patients had 30 polyps (range, 0.2-2.0 cm) by colonscopy, and all polyps > or = 0.5 cm were adenomas. Polyp detection by CTC for both observers was 100% (5 of 5) > or = 1 cm, 71% (5 of 7) between 0.5 and 0.9 cm, and 11%-28% (2-5 of 18) < 0.5 cm. CONCLUSIONS: Based on this small, unblinded pilot study, CTC is feasible for colorectal polyp detection > or = 0.5 cm in diameter.

Aged↗

PubMed1996

Technical exhibits.

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Exhibitions as Topic↗

PubMed1995

Breast dose during electron-beam CT: measurement with film dosimetry.

PURPOSE: To measure the breast dose and dose distribution from examinations performed with electron-beam computed tomography (CT). MATERIALS AND METHODS: Radiographic film was placed bilaterally at three depths in the breasts of an anthropomorphic phantom and exposed with clinically relevant protocols. The average breast dose and the dose distribution were obtained from the digitized and calibrated film and compared with those obtained with conventional CT. RESULTS: Breast doses from electron-beam CT chest, coronary artery calcium, and cardiac function examinations were 21.9, 2.87, and 1.55 mGy, respectively. Within the breast, the dose decreased linearly by a factor of three from the axilla to the sternum. The breast dose from a conventional CT chest examination ranged from 18 to 33 mGy and did not vary substantially across the breast. CONCLUSION: For chest examinations, the average breast dose from an electron-beam CT scanner was comparable to that from conventional CT scanners, despite the differences in dose distribution.

Breast↗

PubMed1995

Electron-beam CT: use of a calibration phantom to reduce variability in calcium quantitation.

PURPOSE: To measure scanner and patient variation in computed tomographic (CT) numbers for electron-beam CT and to determine the ability of calibration phantoms to reduce variability in calcium quantitation. MATERIALS AND METHODS: Two calibration phantoms were imaged to ensure longitudinal homogeneity and to determine the short-term intrascanner variation in CT numbers. Each phantom set was imaged twice a day for 14 weeks to determine intra- and interscanner variation. Data from examinations of 167 patients that included the phantom were analyzed to determine the intra- and interpatient variation in CT numbers of objects with known calcium concentrations. RESULTS: The calibration reduced scanner variations by approximately 25%. The calcium concentration associated with a CT number of 130 HU varied from 77.1 to 136.4 mg/cm3 and was dependent on patient girth, sex, smoking history, and image level. CONCLUSION: Scanner and patient variations in CT numbers in electron-beam CT can be reduced with a calibration phantom. In vitro and in vivo estimates of calcium concentration had a precision of 2% and 7%, respectively.

Adult↗

PubMed1994

The measurement of radiation dose profiles for electron-beam computed tomography using film dosimetry.

The unique geometry of electron-beam CT (EBCT) scanners produces radiation dose profiles with widths which can be considerably different from the corresponding nominal scan width. Additionally, EBCT scanners produce both complex (multiple-slice) and narrow (3 mm) radiation profiles. This work describes the measurement of the axial dose distribution from EBCT within a scattering phantom using film dosimetry methods, which offer increased convenience and spatial resolution compared to thermoluminescent dosimetry (TLD) techniques. Therapy localization film was cut into 8 x 220 mm strips and placed within specially constructed light-tight holders for placement within the cavities of a CT Dose Index (CTDI) phantom. The film was calibrated using a conventional overhead x-ray tube with spectral characteristics matched to the EBCT scanner (130 kVp, 10 mm A1 HVL). The films were digitized at five samples per mm and calibrated dose profiles plotted as a function of z-axis position. Errors due to angle-of-incidence and beam hardening were estimated to be less than 5% and 10%, respectively. The integral exposure under film dose profiles agreed with ion-chamber measurements to within 15%. Exposures measured along the radiation profile differed from TLD measurements by an average of 5%. The film technique provided acceptable accuracy and convenience in comparison to conventional TLD methods, and allowed high spatial-resolution measurement of EBCT radiation dose profiles.

Electrons↗

PubMed1994

Technical exhibits.

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Diagnostic Imaging↗

PubMed1994

Small lesions in the heart identified at electron beam CT: calcification or noise?

PURPOSE: To identify a minimum definition of coronary artery calcification (CAC) at electron beam computed tomography (CT) that would give repeatable results and be accurate as a marker for coronary artery disease. MATERIALS AND METHODS: Hyperattenuating (> 130 HU) foci 0.69-3.09 mm2 in area were evaluated for 256 subjects who underwent two sequential electron beam CT examinations to determine the percentage of hyperattenuating foci seen on a first examination that were seen again on a second examination. Accuracies of varying minimum definitions of CAC were determined in 160 subjects who underwent electron beam CT and coronary arteriography. RESULTS: Hyperattenuating foci more than 2 mm2 in area were seen again at a second examination in more than 50% of cases (P < .0001). At this minimum definition of CAC, the sensitivity and specificity for identifying any angiographically defined coronary artery disease were 82% and 85%, respectively. CONCLUSION: The 2-mm2-area definition of CAC was reliable and provided an accurate indication of coronary artery disease.

Adult↗