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Medical Physics |
1 From the Department of Diagnostic and Interventional Radiology, University Hospital Essen, Hufelandstrasse 55, 45122 Essen, Germany. From the 2001 RSNA scientific assembly. Received August 13, 2001; revision requested September 26; final revision received April 8, 2002; accepted May 23. Address correspondence to J.B. (e-mail: joerg.barkhausen@uni-essen.de).
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ABSTRACT |
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 TOP ABSTRACT INTRODUCTIONMATERIALS AND METHODSRESULTSDISCUSSIONREFERENCES |
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MATERIALS AND METHODS: An anthropomorphic phantom equipped with 66 thermoluminescent dosimeters was imaged at cardiac CT. Four protocols for unenhanced coronary artery calcium scoring were simulated: one with electron-beam CT and three with multi–detector row CT. Four similar protocols for coronary CT angiography were simulated. All multi–detector row spiral CT protocols were performed with retrospective electrocardiographic triggering. Biplane catheter coronary angiography also was simulated. Radiation doses to organs were measured, and effective doses were calculated according to guidelines published in International Commission on Radiological Protection Publication 60.
RESULTS: Coronary artery calcium scoring with electron-beam CT yielded effective radiation doses of 1.0 and 1.3 mSv for male and female patients, respectively. The radiation doses at calcium scoring with multi–detector row CT were 1.5–5.2 mSv for male patients and 1.8–6.2 mSv for female patients. Electron-beam CT coronary angiography yielded effective doses of 1.5 and 2.0 mSv for male and female patients, respectively. The highest effective doses were delivered at multi–detector row CT angiography: 6.7–10.9 mSv for male patients and 8.1–13.0 mSv for female patients. Catheter coronary angiography yielded effective doses of 2.1 and 2.5 mSv for male and female patients, respectively.
CONCLUSION: Higher radiation doses are delivered at multi–detector row cardiac CT compared with the doses delivered at electron-beam CT and catheter coronary angiography.
© RSNA, 2002
Index terms: Computed tomography (CT), electron beam, 54.12111, 54.12112, 54.12115, 54.12116 • Computed tomography (CT), multi–detector row, 54.12111, 54.12112, 54.12115, 54.12116 • Computed tomography (CT), radiation exposure, 54.12111, 54.12112, 54.12115, 54.12116 • Coronary vessels, CT, 54.12111, 54.12112, 54.12115, 54.12116 • Dosimetry
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INTRODUCTION |
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TOPABSTRACTINTRODUCTIONMATERIALS AND METHODSRESULTSDISCUSSIONREFERENCES |
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Recent hardware developments that enable gantry rotations in 500 msec or less with four or more parallel detector rows, in conjunction with software innovations, including prospective electrocardiographic triggering and retrospective electrocardiographic gating, have led to the possibility of assessing coronary arteries with multi–detector row spiral CT. Systems with such advancements can yield a temporal resolution of 250 msec with higher spatial resolution compared with the temporal and spatial resolutions achieved with electron-beam CT (18,19). Preliminary results are encouraging: They indicate that both calcium scoring (20,21) and coronary angiography (22–28) are feasible with multi–detector row spiral CT.
Because of rapid technical advances, scanning protocols for multi–detector row spiral CT have not yet been standardized. Controversies about optimal tube current and voltage are ongoing. At the same time, the availability of multi–detector row CT scanners, as well as the number of multi–detector row CT examinations of the coronary vasculature performed, is rapidly increasing. Study results (29–32) indicate that the radiation doses delivered at cardiac multi–detector row CT may exceed those delivered at electron-beam CT. Few data from comparisons of the radiation exposures with these two cardiac CT examinations have been published, however (24).
The purposes of this study were to measure the effective radiation doses delivered at electron-beam CT and multi–detector row CT for coronary artery calcium quantification and coronary angiography by using the same technique and to compare these doses with those delivered at catheter coronary angiography.
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MATERIALS AND METHODS |
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TOPABSTRACTINTRODUCTIONMATERIALS AND METHODSRESULTSDISCUSSIONREFERENCES |
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Multi–Detector Row CT
Multi–detector row CT scans were obtained by using a commercially available four–detector row scanner (Somatom Volume Zoom). An external electrocardiographic simulator (heart rate, 60 beats per minute) was used for triggering; with this scanner, the table feed is not influenced by the patient’s heart rate. After the topographic scan was obtained, an 11-cm volume from the phantom’s tracheal bifurcation to the apex of the heart was scanned, as was done at electron-beam CT. For sequential (ie, nonspiral) protocols, the exposure time per tube rotation was 0.36 second; therefore, the effective milliampere second product was 36 mAs for a tube current of 100 mA, as recommended by the manufacturer (Table 1).
For spiral CT protocols, the relationship between tube current and effective milliampere second product is expressed as follows: tube current = (effective milliampere second product/T) x pitch, where T is the tube rotation time. Thus, for default cardiac spiral CT protocols (in which T equals 0.5 second and the pitch is 0.375) performed with the four–detector row scanner used in this study, the effective milliampere second product is calculated as follows: effective milliampere second product = (T/pitch) x tube current, which equals 4/3 x tube current. According to the International Electrotechnical Commission, pitch is defined as follows: pitch = (table feed x rotation time)/total nominal section width (33).
Catheter Coronary Angiography
A standard diagnostic coronary angiographic examination consisting of fluoroscopy and cine imaging was simulated by using a biplane angiographic system (HiCor; Siemens, Erlangen, Germany). This protocol consisted of biplane angiography of the left coronary artery with two radiation exposures in four orientations and of the right coronary artery with two exposures in two orientations, as is routinely performed in our cardiology department. With one tube, the left coronary artery was imaged in the following orientations: 30° right anterior oblique, posteroanterior, 30° right anterior oblique with 30° cranial angulation, and 30° right anterior oblique with 30° caudal angulation. With the other tube, the left coronary artery was imaged in the following orientations: 60° left anterior oblique, 90° left anterior oblique, 60° left anterior oblique with 30° cranial angulation, and 60° left anterior oblique with 60° caudal angulation.
Angiography of the right coronary artery was performed in the following orientations: 30° right anterior oblique and 75° right anterior oblique with one tube, and 40° left anterior oblique and 20° left anterior oblique with the other tube. To avoid radiation exposure beyond the examination of the coronary vasculature, we did not simulate cine left ventriculography, which accounts for a major degree of the radiation delivered to patients in routine diagnostic catheterization procedures.
An experienced investigator (A.S.) delivered the radiation to the phantom to simulate a complete angiographic procedure. The mean time to perform fluoroscopy in the four simulations (2.2, 2.4, 2.5, and 2.6 minutes) was 2.4 minutes, which is consistent with the mean times to perform diagnostic procedures in our cardiology department. The tube voltage for fluoroscopy and cine imaging was automatically adjusted and ranged from 68 to 79 kV in these settings.
Dosimetry
The anthropomorphic phantom used in this study consists of 35 2.5-cm-thick sections and simulates the body of a 170-cm-tall, 70-kg male human. The phantom is composed of a human skeleton embedded in a mass with properties of human soft tissue (specific gravity, 0.985 kg/dm3; mean atomic number, 7.3). The thorax of the phantom is made of foam (specific gravity, 0.32 kg/dm3; mean atomic number, 7.3) to simulate human lung tissue. A 7 x 4 x 2-cm rectangular plastic block with isodense properties of a breast, which is similar to the phantom described by Huda and Sandison (36), served as the phantom for the breast radiation dose measurements (34,35).
The phantom was equipped with a total of 66 lithium fluoride TLDs (TLD-100; Bicron-Harshaw, Cleveland, Ohio) positioned between sections 3 and 34. The size of these dosimeters was 6 x 1 x 1 mm. Thirty-three positions on the phantom were equipped with two TLDs each to minimize bias due to measurement deviation. The Figure shows the phantom positioned on the multi–detector row CT table. The distribution of the TLDs at the approximate organ positions and the corresponding sections on the phantom are listed in Table 3. The numbers of TLDs distributed at different organ positions were as follows: There were 20 TLDs at regions of red bone marrow: four at the skull, two at the scapula and clavicle, four at the ribs, four at the spinal column, and six at the pelvis and sacrum. There were two TLDs at the thyroid gland, four at the esophagus, 12 at the lungs, two at the breasts, four at the skin, two at the stomach, two at the liver, eight at the colon, two at the bladder, four at the ovaries, and four at the testicles.
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The effective radiation dose was calculated, according to guidelines published in International Commission on Radiological Protection (ICRP) Publication 60 (37), by summing the products of the measured mean organ dose and the ICRP weighting factors. The radiation doses measured in simulated small organs, such as the thyroid gland and ovaries, were directly factored into the calculation. Radiation doses to simulated larger organs, such as the lungs, were determined by calculating the mean of several TLD measurements from the entire organ. Sex-related differences in radiation doses to male and female patients were taken into account: The radiation dose to the testicles accounted for the male-specific gonad dose, whereas doses to the breasts and ovaries were used to measure radiation doses for female patients.
The SD of lithium fluoride TLD measurements has been determined to be ±8.5% in these particular settings (ie, with the described phantom, TLDs, and analyses). With use of lithium fluoride TLDs, there is negligible fading of charge values within the 24 hours between radiation exposure and dose measurement evaluation at room temperature. TLD outlier points (a total of 21) were discarded from the data set in this study.
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RESULTS |
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TOPABSTRACTINTRODUCTIONMATERIALS AND METHODSRESULTSDISCUSSIONREFERENCES |
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We observed only marginal differences in radiation doses to the different organ positions between the multi–detector row spiral CT and electron-beam CT protocols. The highest doses were measured in the lungs and breasts at all examinations. The esophagus and the regions of red bone marrow were the third and fourth most exposed organs, respectively, followed by the stomach. All of these organs, or at least greater parts of them, were situated within the scanning volume.
CT Coronary Angiography
The data in Table 5 show that similar to the radiation doses delivered at coronary artery calcium scoring with unenhanced electron-beam CT, the doses at electron-beam CT were the lowest in the coronary angiographic examinations. Electron-beam CT coronary angiography yielded an effective dose of 1.5 mSv for male patients and 2.0 mSv for female patients. The higher radiation exposure at electron-beam CT coronary angiography compared with that at unenhanced electron-beam CT calcium scoring was owing to the use of a pitch of 0.66 (section thickness, 3 mm; table feed, 2 mm) instead of 1.00, as was used for calcium scoring. Therefore, the effective radiation dose at electron-beam CT coronary angiography was 1.5-fold higher.
The multi–detector row CT protocol that yielded the lowest effective radiation dose was that described by Achenbach et al (24,25): 6.7 mSv for male patients and 8.1 mSv for female patients, which are 4.0–4.5-fold higher than the effective doses delivered at electron-beam CT. The manufacturer-recommended protocol for multi–detector row spiral CT coronary angiography yielded the highest effective radiation doses overall: 10.9 mSv for male patients and 13.0 mSv for female patients. Another multi–detector row spiral CT protocol, that described by Schroeder et al (27,28) involving a three-fourths decrease in tube current (225 mA instead of 300 mA), correspondingly yielded effective radiation doses of 7.6 and 9.2 mSv for male and female patients, respectively.
Few differences in the radiation doses delivered to the different organ positions were observed between the electron-beam CT and multi–detector row CT protocols for coronary angiography. Similar to the doses delivered at unenhanced coronary artery calcium scoring, the highest organ doses were measured in the lungs and breasts at all CT angiographic examinations. The esophagus was the third most exposed organ, followed by the stomach and the red bone marrow regions.
Catheter Coronary Angiography
The effective radiation dose delivered by using our institution’s standard catheter coronary angiographic protocol was 2.1 mSv for male patients and 2.5 mSv for female patients. There were some differences in organ dose distribution between the standard catheter angiographic and CT angiographic protocols. The lungs, stomach, and ovaries received relatively higher doses than the other organs at catheter angiography compared with the organ dose distributions at the CT angiographic examinations.
With all of the CT protocols, the effective radiation doses for female patients were, on average, 23% higher than those for male patients owing to the high radiation dose to the breasts in the center of the scanning volume. For the same reason, the effective radiation dose for catheter angiography in female patients was 19% higher.
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DISCUSSION |
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TOPABSTRACTINTRODUCTIONMATERIALS AND METHODSRESULTSDISCUSSIONREFERENCES |
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1. Higher radiation doses are delivered at multi–detector row cardiac CT compared with those delivered at electron-beam CT and invasive catheter coronary angiographic examinations.
2. The effective radiation doses for different CT protocols are highly variable.
3. The high effective radiation doses at cardiac CT warrant a strong clinical indication and the use of optimized and standardized imaging protocols.
Multi–detector row CT was introduced into clinical radiology practice in 1999 (38). Advantages in image quality and speed of anatomic coverage have been reported (39,40). Immediately after the introduction of multi–detector row CT, there was much interest in its potential for cardiovascular imaging. The acceptable temporal resolution and excellent spatial resolution of multi–detector row CT have made coronary artery imaging with this modality possible. Unlike electron-beam CT, multi–detector row CT scanners can be used routinely for the entire spectrum of CT examinations. Accordingly, the number of available multi–detector row spiral CT scanners is rapidly increasing. Therefore, the number of cardiac CT examinations performed can be expected to increase rapidly.
There is controversy regarding the effect that the radiation exposure at cardiac CT has on the use of this modality. The radiation doses delivered with the different modalities and protocols have been assessed or estimated by using different methods, and this has led to inconsistent results (30,34). In the present study, we measured the effective radiation doses delivered with different imaging modalities and different imaging protocols by using the same dose measurement method, which facilitated a direct comparison of the doses delivered with the different imaging procedures.
Electron-Beam CT versus Multi–Detector Row CT
The effective radiation doses at unenhanced electron-beam CT calcium scoring were 1.0 and 1.3 mSv for male and female patients, respectively. With use of prospective triggering and a sequential (ie, nonspiral) multi–detector row CT protocol, the effective doses were slightly higher than those at electron-beam CT. The radiation exposure at multi–detector row CT performed with spiral protocols and retrospective electrocardiographic gating, however, was at least threefold higher than that at electron-beam CT: The manufacturer-recommended spiral protocol for multi–detector row CT calcium scoring yielded a fivefold higher effective dose compared with that at electron-beam CT calcium scoring.
In the noninvasive CT coronary angiographic examinations, electron-beam CT coronary angiography yielded an effective radiation dose of 1.5 mSv for male patients and 2.0 mSv for female patients. Higher doses were measured at multi–detector row CT, reflecting the higher tube current, continuous exposure during the entire cardiac cycle, and scan overlap (29). Effective doses at multi–detector row CT coronary angiography of 6.7–10.9 mSv and 8.1–13.0 mSv were observed for male and female patients, respectively, depending on the protocol. The radiation exposure with the multi–detector row CT protocol that yielded the lowest effective radiation dose, that recommended by Achenbach et al (24,25), exceeded the exposure at electron-beam CT angiography and catheter angiography by a factor of 3. We observed the effective doses with different multi–detector row CT protocols to be highly variable and strongly dependent on the scanning parameters (ie, tube voltage and tube current).
Cardiac CT versus Catheter Coronary Angiography
Our simulations of angiographic procedures were based on the standard diagnostic protocol used in the cardiology department of our institution. The mean time to perform fluoroscopy in the four examinations was 2.4 minutes, which corresponds to the mean time for this procedure in our cardiology department. The effective radiation doses at simulated catheter angiography (2.1 mSv for male patients, 2.5 mSv for female patients) were lower than those published in other studies, most probably because of the shorter radiation exposure times. In two studies involving the use of the Alderson phantom, effective radiation doses of 3.1 mSv (41) and 3.3 mSv (30) were measured. Other groups have used dose area products to calculate effective doses of 5.0 mSv (42) and 5.6 mSv (43). There were two major limitations of our catheter angiography measurements: First, since effective radiation doses increase proportionally to radiation exposure times, one cannot generalize the doses for catheter angiography from our measurements. Second, the doses that we measured may have been too low, because the Alderson phantom that we used is a simulation of a slim patient (body weight, 70 kg). For obese patients, the automatic brightness control on the biplane catheter angiographic system would increase the tube current, and this would result in a higher effective dose, whereas at CT angiography, radiation exposure is relatively independent of patient size.
The effective radiation doses delivered at calcium scoring with electron-beam CT and sequential multi–detector row CT are about half the inherent mean level of exposure to natural background radiation each year in Germany (2.4 mSv/yr) and fivefold to ninefold higher than the dose delivered at conventional chest radiography (0.2 mSv). With use of spiral CT protocols, the effective radiation doses for calcium scoring are lower than those for standard thoracic CT examinations, which are reported to be in the range of 5.0–12.9 mSv (34,44). They are also slightly higher than or in the order of those associated with diagnostic catheter coronary angiography (30,41–43). The effective radiation doses at multi–detector row CT coronary angiography are higher than those at standard thoracic CT examinations.
Dose Measurements versus Dose Estimations
The radiation doses with the CT coronary angiography protocol used by Achenbach et al (24,25) that we measured were higher than the doses estimated by the authors themselves by using a personal computer program (WinDose; Wellhöfer Dosimetrie/Scanditronix Medical, Schwarzenbruck, Germany): 6.7 mSv versus 3.9 mSv for male patients and 8.1 mSv versus 5.8 mSv for female patients. Similar to us, Cohnen et al (34) reported that dose calculations based on the CT dose index are underestimations of the effective dose compared with actual dose measurements.
When we compared the different effective radiation dose measurements by using the Alderson phantom, the doses measured at electron-beam CT calcium scoring (eg, 1.0 mSv for male patients) were similar to those measured by Becker et al (30), who observed an effective dose of 0.8 mSv for male patients with use of the same protocol. The more recently published data of Cohnen et al (34) show excellent agreement between the doses that they measured and those that we measured with use of identical protocols: the manufacturer-recommended multi–detector spiral CT protocols for calcium scoring and coronary angiography. Therefore, we suggest that dose measurements obtained by using the Alderson phantom are highly reliable and reproducible for cardiac CT examinations.
Clinical Implications
The radiation doses delivered at cardiac CT are similar in magnitude to those received from natural background radiation for 1 year. Although there is considerable debate about the risk associated with such dose levels, ALARA ("as low as reasonably achievable") principles mandate that such doses be used in a responsible manner. There are some important issues to be considered in this regard.
First, there has to be a strong indication to perform a cardiac CT examination. Coronary artery calcium quantification has been demonstrated to have considerable prognostic value in selected subgroups of patients (45). In such patients, the benefit of calcium scoring appears to clearly outweigh the risk of radiation damage. The use of calcium scoring as a general screening tool is unwarranted, however. Guidelines for the use of calcium scoring in asymptomatic patients have been defined (46). The value of calcium scoring in patients with stable angina has been demonstrated (45); however, the clinical importance of the results of this examination in unstable patients remains unclear (47). The importance of CT coronary angiography still needs to be defined.
Second, the need for standardized and optimized cardiac CT protocols is evident. Similar to guidelines for performing electron-beam CT, consensus recommendations for the use of multi–detector row CT are needed. The German Cardiac Society work group that is responsible for investigating and monitoring the use of fast CT examinations recently released recommendations for performing calcium scoring with multi–detector row CT, which will soon be published. A number of different protocols for performing multi–detector row CT coronary angiography have been proposed. The tube voltages in the published protocols vary from 120 to 140 kV, and the tube currents vary between 150 and 225 mA (24,27,48). There remains controversy regarding the optimal protocol—that is, one that combines low radiation exposure with diagnostic image quality to meet the ALARA principles. In this respect, larger studies need to be undertaken.
Some promising features of tube current modulation during systole and diastole are believed to help reduce radiation exposure substantially without decreasing diagnostic image quality (49,50). The results of some more recently published studies (29,51) of radiation doses at CT demonstrate the potential to decrease effective radiation doses by modifying the tube current and pitch and implementing a body weight adjustment of the tube current at conventional thoracic CT examinations. Whether these modifications can be applied to cardiac CT remains to be proven.
Third, high radiation exposures at cardiac CT oblige investigators to obtain the highest diagnostic accuracy from the information provided. Important parts of the lung are irradiated but not depicted in the small cardiac field of view and at soft tissue window settings. In a previously published study (52), 53% (953 of 1,812) of patients who underwent cardiac CT had noncoronary and extracardiac incidental findings; 0.2% of the patients in that study had malignant disease. The published CT data of Henschke et al (53) from the Early Lung Cancer Action Project showed a prevalence of lung cancer of 2.7% and a prevalence of other malignant thoracic disease of 0.4% in a population of 1,000 symptom-free smoking volunteers aged 60 years or older. The examined population was very similar to the general patient cohort referred for cardiac CT. These findings suggest that a large number of cases of malignant thoracic disease may be missed at diagnosis when conventional cardiac reconstructions are used. Without an increase in radiation dose, screening imaging could be extended to other thoracic organs. For these reasons, we suggest that the high-quality data sets obtained at cardiac CT be additionally reconstructed at lung window settings and with a large field of view. Furthermore, image interpretation and reporting of the results should be performed by physicians who are experienced in thoracic radiology.
In conclusion, the rapidly increasing number of cardiac imaging–suitable CT scanners indicates that an increasing number of cardiac CT examinations are being performed. Because cardiac CT examinations involve substantial radiation doses, strong indications for the procedure and improved and standardized scanning protocols are needed.
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FOOTNOTES |
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Author contributions: Guarantors of integrity of entire study, P.H., J.B., J.F.D.; study concepts and design, all authors; literature research, P.H., J.B., A.S.; experimental studies, P.H., F.M.V., J.B.; data acquisition, P.H., F.M.V., A.S., G.K., K.E.; data analysis/interpretation, P.H., J.B., J.F.D., T.B., R.E., K.E.; manuscript preparation, P.H., F.M.V., A.S., J.B.; manuscript definition of intellectual content, P.H., J.F.D., J.B.; manuscript editing, P.H., J.B.; manuscript revision/review, P.H., A.S., T.B., R.E., J.F.D., J.B.; manuscript final version approval, all authors.
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TOPABSTRACTINTRODUCTIONMATERIALS AND METHODSRESULTSDISCUSSIONREFERENCES |
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 D. D. Cody and M. Mahesh AAPM/RSNA Physics Tutorials AAPM/RSNA Physics Tutorial for Residents: Technologic Advances in Multidetector CT with a Focus on Cardiac Imaging RadioGraphics, November 1, 2007; 27(6): 1829 - 1837. [Abstract] [Full Text] [PDF]
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 G. T. Wilson, P. Gopalakrishnan, and T. Tak Noninvasive Cardiac Imaging with Computed Tomography Clin. Med. Res., October 1, 2007; 5(3): 165 - 171. [Abstract] [Full Text] [PDF]
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A. J. Einstein, K. W. Moser, R. C. Thompson, M. D. Cerqueira, and M. J. Henzlova Radiation Dose to Patients From Cardiac Diagnostic Imaging Circulation, September 11, 2007; 116(11): 1290 - 1305. [Full Text] [PDF]
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M. Mahesh and D. D. Cody AAPM/RSNA Physics Tutorial for Residents: Physics of Cardiac Imaging with Multiple-Row Detector CT RadioGraphics, September 1, 2007; 27(5): 1495 - 1509. [Abstract] [Full Text] [PDF]
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G. Hur, S. W. Hong, S. Y. Kim, Y. H. Kim, Y. J. Hwang, W. R. Lee, and S. J. Cha Uniform Image Quality Achieved by Tube Current Modulation Using SD of Attenuation in Coronary CT Angiography Am. J. Roentgenol., July 1, 2007; 189(1): 188 - 196. [Abstract] [Full Text] [PDF]
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T. Schlosser, P. Hunold, T. Voigtlander, A. Schmermund, and J. Barkhausen Coronary Artery Calcium Scoring: Influence of Reconstruction Interval and Reconstruction Increment Using 64-MDCT Am. J. Roentgenol., April 1, 2007; 188(4): 1063 - 1068. [Abstract] [Full Text] [PDF]
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 C. M. Jones, T. Athanasiou, N. Dunne, J. Kirby, O. Aziz, A. Haq, C. Rao, V. Constantinides, S. Purkayastha, and A. Darzi Multi-Detector Computed Tomography in Coronary Artery Bypass Graft Assessment: A Meta-Analysis Ann. Thorac. Surg., January 1, 2007; 83(1): 341 - 348. [Abstract] [Full Text] [PDF]
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 H. Schoder and M. Gonen Screening for Cancer with PET and PET/CT: Potential and Limitations J. Nucl. Med., January 1, 2007; 48(1_suppl): 4S - 18S. [Abstract] [Full Text] [PDF]
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H. Dogan, L. J. M. Kroft, M. V. Huisman, R. J. van der Geest, and A. de Roos Right Ventricular Function in Patients with Acute Pulmonary Embolism: Analysis with Electrocardiography-synchronized Multi-Detector Row CT Radiology, December 1, 2006; 242(1): 78 - 84. [Abstract] [Full Text] [PDF]
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 S. Achenbach Computed Tomography Coronary Angiography J. Am. Coll. Cardiol., November 21, 2006; 48(10): 1919 - 1928. [Abstract] [Full Text] [PDF]
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M. Hamon, G. G.L. Biondi-Zoccai, P. Malagutti, P. Agostoni, R. Morello, M. Valgimigli, and M. Hamon Diagnostic Performance of Multislice Spiral Computed Tomography of Coronary Arteries as Compared With Conventional Invasive Coronary Angiography: A Meta-Analysis J. Am. Coll. Cardiol., November 7, 2006; 48(9): 1896 - 1910. [Abstract] [Full Text] [PDF]
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M. J. Budoff, S. Achenbach, R. S. Blumenthal, J. J. Carr, J. G. Goldin, P. Greenland, A. D. Guerci, J. A.C. Lima, D. J. Rader, G. D. Rubin, et al. Assessment of Coronary Artery Disease by Cardiac Computed Tomography: A Scientific Statement From the American Heart Association Committee on Cardiovascular Imaging and Intervention, Council on Cardiovascular Radiology and Intervention, and Committee on Cardiac Imaging, Council on Clinical Cardiology Circulation, October 17, 2006; 114(16): 1761 - 1791. [Full Text] [PDF]
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T. K Mittal, M. Barbir, and M. Rubens Role of computed tomography in risk assessment for coronary heart disease. Postgrad. Med. J., October 1, 2006; 82(972): 664 - 671. [Abstract] [Full Text] [PDF]
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 C. M. Jones, T. Athanasiou, N. Dunne, J. Kirby, S. Attaran, A. Chow, S. Purkayastha, and A. Darzi Multi-slice computed tomography in coronary artery disease. Eur. J. Cardiothorac. Surg., September 1, 2006; 30(3): 443 - 450. [Abstract] [Full Text] [PDF]
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E. Coche, S. Vynckier, and M. Octave-Prignot Pulmonary Embolism: Radiation Dose with Multi-Detector Row CT and Digital Angiography for Diagnosis Radiology, September 1, 2006; 240(3): 690 - 697. [Abstract] [Full Text] [PDF]
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J. Horiguchi, H. Yamamoto, N. Hirai, Y. Akiyama, C. Fujioka, K. Marukawa, H. Fukuda, and K. Ito Variability of repeated coronary artery calcium measurements on low-dose ECG-gated 16-MDCT. Am. J. Roentgenol., July 1, 2006; 187(1): W1 - W6. [Abstract] [Full Text] [PDF]
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K. Nikolaou, A. Knez, C. Rist, B. J. Wintersperger, A. Leber, T. Johnson, M. F. Reiser, and C. R. Becker Accuracy of 64-MDCT in the diagnosis of ischemic heart disease. Am. J. Roentgenol., July 1, 2006; 187(1): 111 - 117. [Abstract] [Full Text] [PDF]
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G. M. Feuchtner, W. Dichtl, T. Schachner, S. Muller, A. Mallouhi, G. J. Friedrich, and D. z. Nedden Diagnostic performance of MDCT for detecting aortic valve regurgitation. Am. J. Roentgenol., June 1, 2006; 186(6): 1676 - 1681. [Abstract] [Full Text] [PDF]
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V. D. Raptopoulos, P. B. Boiselle, N. Michailidis, J. Handwerker, A. Sabir, J. A. Edlow, I. Pedrosa, and J. B. Kruskal MDCT Angiography of Acute Chest Pain: Evaluation of ECG-Gated and Nongated Techniques Am. J. Roentgenol., June 1, 2006; 186(6_Supplement_2): S346 - S356. [Abstract] [Full Text] [PDF]
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D. R. Coles, M. A. Smail, I. S. Negus, P. Wilde, M. Oberhoff, K. R. Karsch, and A. Baumbach Comparison of Radiation Doses From Multislice Computed Tomography Coronary Angiography and Conventional Diagnostic Angiography J. Am. Coll. Cardiol., May 2, 2006; 47(9): 1840 - 1845. [Abstract] [Full Text] [PDF]
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G. M. Feuchtner, W. Dichtl, G. J. Friedrich, M. Frick, H. Alber, T. Schachner, J. Bonatti, A. Mallouhi, T. Frede, O. Pachinger, et al. Multislice Computed Tomography for Detection of Patients With Aortic Valve Stenosis and Quantification of Severity J. Am. Coll. Cardiol., April 4, 2006; 47(7): 1410 - 1417. [Abstract] [Full Text] [PDF]
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D. V. Anand, E. Lim, A. Lahiri, and J. J. Bax The role of non-invasive imaging in the risk stratification of asymptomatic diabetic subjects Eur. Heart J., April 2, 2006; 27(8): 905 - 912. [Abstract] [Full Text] [PDF]
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G. Pache, U. Saueressig, A. Frydrychowicz, D. Foell, N. Ghanem, E. Kotter, A. Geibel-Zehender, C. Bode, M. Langer, and T. Bley Initial experience with 64-slice cardiac CT: non-invasive visualization of coronary artery bypass grafts Eur. Heart J., April 2, 2006; 27(8): 976 - 980. [Abstract] [Full Text] [PDF]
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D. V. Anand, E. Lim, D. Hopkins, R. Corder, L. J. Shaw, P. Sharp, D. Lipkin, and A. Lahiri Risk stratification in uncomplicated type 2 diabetes: prospective evaluation of the combined use of coronary artery calcium imaging and selective myocardial perfusion scintigraphy Eur. Heart J., March 2, 2006; 27(6): 713 - 721. [Abstract] [Full Text] [PDF]
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J. F. Bruzzi, M. Remy-Jardin, D. Delhaye, A. Teisseire, C. Khalil, and J. Remy When, Why, and How to Examine the Heart During Thoracic CT: Part 1, Basic Principles Am. J. Roentgenol., February 1, 2006; 186(2): 324 - 332. [Abstract] [Full Text] [PDF]
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M. E. Clouse, J. Chen, H. M. Krumholz, M. E. Clouse, J. Chen, and H. M. Krumholz Noninvasive Screening for Coronary Artery Disease With Computed Tomography Is Useful Circulation, January 3, 2006; 113(1): 125 - 146. [Full Text] [PDF]
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J. J. W. Sandstede, J. Stoffels, F. Wendel, C. Ritter, M. Beer, and D. Hahn Different Reconstruction Intervals for Exclusion of Coronary Artery Calcifications by Retrospectively Gated MDCT Am. J. Roentgenol., January 1, 2006; 186(1): 193 - 197. [Abstract] [Full Text] [PDF]
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M. Schwaiger, S. Ziegler, and S. G. Nekolla PET/CT: Challenge for Nuclear Cardiology J. Nucl. Med., October 1, 2005; 46(10): 1664 - 1678. [Abstract] [Full Text] [PDF]
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S. Achenbach, D. Ropers, F.-K. Pohle, D. Raaz, J. von Erffa, A. Yilmaz, G. Muschiol, and W. G. Daniel Detection of coronary artery stenoses using multi-detector CT with 16x0.75 collimation and 375 ms rotation Eur. Heart J., October 1, 2005; 26(19): 1978 - 1986. [Abstract] [Full Text] [PDF]
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A. Schmermund and R. Erbel Non-invasive computed tomographic coronary angiography: the end of the beginning Eur. Heart J., August 1, 2005; 26(15): 1451 - 1453. [Full Text] [PDF]
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M. J. Budoff, M. C. Cohen, M. J. Garcia, J. McB. Hodgson, W. G. Hundley, J. A.C. Lima, W. J. Manning, G. M. Pohost, P. M. Raggi, G. P. Rodgers, et al. ACCF/AHA Clinical Competence Statement on Cardiac Imaging With Computed Tomography and Magnetic Resonance: A Report of the American College of Cardiology Foundation/American Heart Association/American College of Physicians Task Force on Clinical Competence and Training J. Am. Coll. Cardiol., July 19, 2005; 46(2): 383 - 402. [Full Text] [PDF]
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J. Datta, C. S. White, R. C. Gilkeson, C. A. Meyer, S. Kansal, M. L. Jani, R. C. Arildsen, and K. Read Anomalous Coronary Arteries in Adults: Depiction at Multi-Detector Row CT Angiography Radiology, June 1, 2005; 235(3): 812 - 818. [Abstract] [Full Text] [PDF]
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M. Heuschmid, A. Kuettner, S. Schroeder, T. Trabold, A. Feyer, M. D. Seemann, R. Kuzo, C. D. Claussen, and A. F. Kopp ECG-Gated 16-MDCT of the Coronary Arteries: Assessment of Image Quality and Accuracy in Detecting Stenoses Am. J. Roentgenol., May 1, 2005; 184(5): 1413 - 1419. [Abstract] [Full Text] [PDF]
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N. R Mollet, F. Cademartiri, and P. J de Feyter Non-invasive multislice CT coronary imaging Heart, March 1, 2005; 91(3): 401 - 407. [Full Text] [PDF]
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T. Schlosser, K. Pagonidis, C. U. Herborn, P. Hunold, K.-U. Waltering, T. C. Lauenstein, and J. Barkhausen Assessment of Left Ventricular Parameters Using 16-MDCT and New Software for Endocardial and Epicardial Border Delineation Am. J. Roentgenol., March 1, 2005; 184(3): 765 - 773. [Abstract] [Full Text] [PDF]
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N. R. Mollet, F. Cademartiri, G. P. Krestin, E. P. McFadden, C. A. Arampatzis, P. W. Serruys, and P. J. de Feyter Improved diagnostic accuracy with 16-row multi-slice computed tomography coronary angiography J. Am. Coll. Cardiol., January 4, 2005; 45(1): 128 - 132. [Abstract] [Full Text] [PDF]
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 J. D. Schuijf, J. J. Bax, J. W. Jukema, H. J. Lamb, H. W. Vliegen, L. P. Salm, A. de Roos, and E. E. van der Wall Noninvasive Angiography and Assessment of Left Ventricular Function Using Multislice Computed Tomography in Patients With Type 2 Diabetes Diabetes Care, December 1, 2004; 27(12): 2905 - 2910. [Abstract] [Full Text] [PDF]
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E. Martuscelli, A. Romagnoli, A. D'Eliseo, M. Tomassini, C. Razzini, M. Sperandio, G. Simonetti, F. Romeo, and J.L. Mehta Evaluation of Venous and Arterial Conduit Patency by 16-Slice Spiral Computed Tomography Circulation, November 16, 2004; 110(20): 3234 - 3238. [Abstract] [Full Text] [PDF]
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T. Schlosser, T. Konorza, P. Hunold, H. Kuhl, A. Schmermund, and J.o. Barkhausen Noninvasive visualization of coronary artery bypass grafts using 16-detector row computed tomography J. Am. Coll. Cardiol., September 15, 2004; 44(6): 1224 - 1229. [Abstract] [Full Text] [PDF]
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P.J. de Feyter and K. Nieman Noninvasive multi-slice computed tomography coronary angiography: An emerging clinical modality J. Am. Coll. Cardiol., September 15, 2004; 44(6): 1238 - 1240. [Full Text] [PDF]
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U. J. Schoepf, C. R. Becker, B. M. Ohnesorge, and E. K. Yucel CT of Coronary Artery Disease Radiology, July 1, 2004; 232(1): 18 - 37. [Abstract] [Full Text] [PDF]
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J. Horiguchi, H. Yamamoto, Y. Akiyama, K. Marukawa, N. Hirai, and K. Ito Coronary Artery Calcium Scoring Using 16-MDCT and a Retrospective ECG-Gating Reconstruction Algorithm Am. J. Roentgenol., July 1, 2004; 183(1): 103 - 108. [Abstract] [Full Text] [PDF]
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N. R. Mollet, F. Cademartiri, K. Nieman, F. Saia, P. A. Lemos, E. P. McFadden, P. M. T. Pattynama, P. W. Serruys, G. P. Krestin, and P. J. de Feyter Multislice spiral computed tomography coronary angiography in patients with stable angina pectoris J. Am. Coll. Cardiol., June 16, 2004; 43(12): 2265 - 2270. [Abstract] [Full Text] [PDF]
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A. Kuettner, A. F. Kopp, S. Schroeder, T. Rieger, J. Brunn, C. Meisner, M. Heuschmid, T. Trabold, C. Burgstahler, J. Martensen, et al. Diagnostic accuracy of multidetector computed tomography coronary angiography in patients with angiographically proven coronary artery disease J. Am. Coll. Cardiol., March 3, 2004; 43(5): 831 - 839. [Abstract] [Full Text] [PDF]
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M. J. Budoff, S. Achenbach, and A. Duerinckx Clinical utility of computed tomography and magnetic resonance techniques for noninvasive coronary angiography J. Am. Coll. Cardiol., December 3, 2003; 42(11): 1867 - 1878. [Abstract] [Full Text] [PDF]
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