Published online before print August 18, 2003, 10.1148/radiol.2291020717
(Radiology 2003;229:140-144.)
© RSNA, 2003
Lumbar Spine Radiography: Digital Flat-Panel Detector versus Screen-Film and Storage-Phosphor Systems in Monkeys as a Pediatric Model1
Karl Ludwig, MD,
Kathrin Ahlers, BS,
Dag Wormanns, MD,
Michael Freund, MD,
Thomas M. Bernhardt, MD,
Stefan Diederich, MD and
Walter Heindel, MD
1 From the Department of Clinical Radiology, University of Muenster, Germany. Received June 14, 2002; revision requested August 9; final revision received February 9, 2003; accepted February 18. Address correspondence to K.L., Section of Diagnostic Radiology, Department of Orthopedic Surgery, University of Heidelberg, Schlierbacher Landstr 200a, D-69118 Heidelberg, Germany (e-mail: karl.ludwig@ok.uni-heidelberg.de).
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ABSTRACT
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PURPOSE: To assess image quality and exposure dose requirements of a flat-panel detector system versus screen-film and storage-phosphor systems for radiographic depiction of the lumbar spine in Cynomolgus monkeys as a pediatric model.
MATERIALS AND METHODS: Twenty Cynomolgus monkeys underwent anteroposterior radiography of the lumbar spine. The size and weight of these monkeys are comparable to those of infants 3–4 months of age. Images were acquired with speed class 400 screen-film, flat-panel, and storage-phosphor systems with identical exposure dose. All other conditions were matched exactly. Additional images were acquired with the flat-panel and storage-phosphor systems at exposure doses equivalent to speed classes 800 and 1600. All images were obtained at 66 kVp without antiscatter grid. Images were assessed independently by three radiologists for visibility of 60 anatomic structures by using a five-point confidence scale. Scores were calculated for the seven combinations of imaging mode and exposure dose and were compared by using the Friedman test.
RESULTS: Scores were 1.70 (speed class 400), 1.97 (speed class 800), and 2.27 (speed class 1600) for the flat-panel system; 2.50 (speed class 400) for the screen-film system; and 2.58 (speed class 400), 2.77 (speed class 800), and 3.13 (speed class 1600) for the storage-phosphor system. Scores for the flat-panel system at speed classes 400 and 800 were significantly lower (indicating better visibility) than those of the screen-film and storage-phosphor systems (P < .05).
CONCLUSION: The flat-panel system is superior to screen-film and storage-phosphor systems in lumbar spine radiography in monkeys. With the flat-panel system, exposure dose can be reduced by 75% without loss in image quality.
© RSNA, 2003
Index terms: Animals • Experimental study • Flat panel detector • Radiography, comparative studies • Radiography, digital, 33.12 • Radiography, in infants and children, 33.11, 33.12 • Radiography, storage phosphor, 33.12 • Spine, radiography, 33.11, 33.12
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INTRODUCTION
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Large-area direct read-out flat-panel detector radiography systems offer various advantages in comparison to screen-film and storage-phosphor systems: Most important, the detective quantum efficiency is twice as high (1,2). As integrated cassetteless systems, they have been shown to improve workflow (3). In contrast to screen-film systems, they provide a wider range of contrast, are directly connectable to picture archiving and communication systems, and allow dedicated image processing (4,5).
Results of various experimental studies have shown superior image quality and lower exposure dose requirements compared with those of screen-film and storage-phosphor systems for specific skeletal lesions (6–9). Investigators in a few clinical studies have demonstrated superior depiction of anatomic or pathologic skeletal structures and lower exposure dose requirements with flat-panel systems, as well (10–12). These clinical studies were performed in adult patients and involved the comparison of sets of images from different skeletal areas acquired with different tube voltages. Mostly small numbers of patients were examined, and only a few combinations of imaging mode and exposure dose level were compared.
Pediatric patients constitute the most important patient group for exposure dose reductions with flat-panel systems. Radiographic examinations in adult and pediatric patients differ largely in absorption and scatter radiation, however. Since, to our knowledge, there is no systematic evaluation of potentially different effects of scatter radiation with various conventional and digital detector systems, it is likely that study results on the imaging of adult patients are not directly transferable to pediatric patients.
The purpose of our study was to compare image quality and exposure dose requirements of a digital flat-panel detector system with those of screen-film and storage-phosphor systems on images of one anatomic area acquired with identical tube voltage. To assess these elements in pediatric imaging without incurring additional radiation exposure to pediatric patients, we used monkeys to simulate small children with respect to absorption and scatter radiation conditions.
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MATERIALS AND METHODS
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Animal Model
Radiographs of the lumbar spine were acquired in 20 female Cynomolgus monkeys (Macaca fascicularis) with different imaging systems and exposure doses. The monkeys were sedated for approximately 90 minutes with a combination of ketamine (10 mg per kilogram of body weight of Ketalar; Parke-Davis, Morris Plains, NJ) and xylazine (10 mg/kg of Rompun; Bayer, Morristown, NJ). The monkeys had a mean body weight of 4.0 kg (range, 2.8–6.0 kg) and a mean size of 60 cm (range, 50–75 cm). Their mean age was 9.3 years (range, 6–13 years), with a life expectancy of approximately 25 years. During sedation, all monkeys were placed on an x-ray transparent frame with markings for collimation and central beam position to ensure identical positioning with the different imaging modes. Our study had full approval of the Committee on the Use and Care of Laboratory Animals and was in accordance with the Federal Law on the Care and Use of Laboratory Animals.
Imaging Technique
Anteroposterior radiographs of the lumbar spine were obtained with three imaging systems. The first system was a large-area direct read-out flat-panel detector system (Digital Diagnost; Philips Medical Systems, Hamburg, Germany) with a 500-µm layer of cesium iodide for the conversion of x-rays to light and an amorphous silicone matrix for the conversion of light to electrical charge. This detector provides a pixel size of 143 x 143 µm (Nyquist limit, 3.6 line pairs per millimeter) in a 3,000 x 3,000-pixel matrix, resulting in a 43 x 43-cm field of view. The second system was a storage-phosphor system (ADC compact; Agfa, Leverkusen, Germany), which provides a pixel size of 118 x 118 µm (Nyquist limit, 4.2 line pairs per millimeter) when used with a 24 x 30-cm film size. The third system was a speed class 400 screen-film system (Insight Skeletal Regular; Kodak, Rochester, NJ), which provides a spatial resolution of 6.5 line pairs per millimeter.
Special care was taken to match exposure conditions for the three imaging systems as precisely as possible: All imaging was performed with a standard x-ray tube and generator (SRO 33 100 or SCP 80; Philips Medical Systems) and a 0.6-mm focal-spot size. All imaging was performed without antiscatter grid. Geometric image parameters were identical for all imaging modes, with a distance of 115 cm from the focal spot to the object plane and a distance of 8 cm from the object plane to the detector plane. Collimation was chosen once for each individual monkey, depending on its size (range, 4 x 18 cm to 6 x 24 cm). For each monkey, collimation was kept constant for the different imaging modes to avoid systematic errors originating from differences in scatter radiation.
To correspond with routine clinical radiographic procedures of the lumbar spine in pediatric patients, a tube voltage of 66 kVp and a total filtration of 3-mm aluminum were used. For each monkey, a series of images with different exposure doses was obtained to determine the optimum clinical exposure dose for the speed class 400 screen-film system. This exposure dose was used for the speed class 400 screen-film system, the flat-panel system, and the storage-phosphor system and is subsequently referred to as "equivalent to speed class 400."
Additional images were obtained with the flat-panel and storage-phosphor systems at one-half and one-quarter of the exposure dose used with the screen-film system. These additional images are subsequently referred to as "equivalent to speed classes 800 and 1600," respectively. Use of any type of automatic exposure control was intentionally avoided as a potential cause of unsteady exposure with different imaging systems.
The flat-panel and storage-phosphor images were printed on film by using a laser printer (Imation film and/or Imation DryView 8700; Kodak). Look-up tables for both of the digital imaging modes were chosen such that the optical densities, measured with densitometry (Unilight D; Wellhoefer, Schwarzenbruck, Germany) for three predefined locations (paraspinal soft tissues, center of L1 and L3 vertebrae), were identical to those on the speed class 400 screen-film images to avoid any bias caused by differences in brightness or contrast between the imaging modes. All imaging was performed by one author (K.A.), who was not involved in the image evaluation process.
Image Evaluation
All images were assessed independently by three radiologists (M.F., T.M.B., S.D.) for the visibility of 60 anatomic structures (Fig 1). Readers were asked to score the visibility of each of these structures on a five-point scale (1 = excellent visibility, 5 = not visible). This resulted in a total of 25,200 observations (three radiologists times 20 monkeys times 60 anatomic structures times seven combinations of imaging mode and exposure dose). Since the three observers assessed the same 60 details in the 20 monkeys, the observers’ assessments on the same detail were not independent. During image evaluation, anatomic details were shown separately to each of the observers in random order: Part of one image was shown to the observer for assessment of one anatomic detail (eg, the upper endplate of L4), then another part of another image was shown (eg, the right sacral foramina), and so on. The collimation of the light box was used to show only the part of an image that contained the detail of interest. Bias was thereby minimized or excluded in the assessment of one detail by not enabling simultaneous perception of other details on the image. Readers were blinded to exposure settings and imaging mode. To prevent learning bias, all images were shown in random order. A training phase preceded the image evaluation process. No time constraints were used. None of the readers were involved in the imaging process. All images were viewed on the same light box with adjustable shutters and subdued ambient light.
Data Analysis
For each of the seven combinations of imaging mode and exposure dose, a mean score for all anatomic details was calculated for each reader separately and for all readers. For statistical analysis, the three observers’ assessments for each of the details were grouped together, since they were not independent. Because of the process of image evaluation outlined earlier, however, the observations of one observer on the 60 details of one monkey spine were considered independent. Mean scores for all readers were compared by using the Friedman test. SPSS version 10.0.7 software (SPSS, Chicago, Ill) was used for statistical analysis.
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RESULTS
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Mean scores for all anatomic details and for all readers were 1.70 (speed class 400), 1.97 (speed class 800) and 2.27 (speed class 1600) for the flat-panel system; 2.50 (speed class 400) for the screen-film system; and 2.58 (speed class 400), 2.77 (speed class 800) and 3.13 (speed class 1600) for the storage-phosphor system. The graphic depiction of mean scores in Figure 2 shows that scores for the flat-panel and storage-phosphor systems increase with decreasing exposure dose. Examples of images acquired with each of these combinations of imaging mode and exposure dose are shown in Figures 3 and 4.
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Figure 2. Graphic depiction of the mean scores for the different imaging modes and exposure doses shows dependence of image quality on exposure dose with the flat-panel (FPD) and storage-phosphor (SPS) systems. A lower score indicates better image quality. With an exposure dose equivalent to speed class 400, the flat-panel system outperforms the other imaging systems examined. With an exposure dose equivalent to speed class 1600, the flat-panel system is comparable to the speed class 400 screen-film system (SFS).
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Figure 3a. Radiographs of the lumbar spine obtained with (a) the speed class 400 screen-film system; the flat-panel system at exposure doses equivalent to speed classes (b) 400, (c) 800, and (d) 1600; and the storage-phosphor system at exposure doses equivalent to speed classes (e) 400, (f) 800, and (g) 1600. The flat-panel system offers superior image quality to that of screen-film and storage-phosphor systems.
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Figure 3b. Radiographs of the lumbar spine obtained with (a) the speed class 400 screen-film system; the flat-panel system at exposure doses equivalent to speed classes (b) 400, (c) 800, and (d) 1600; and the storage-phosphor system at exposure doses equivalent to speed classes (e) 400, (f) 800, and (g) 1600. The flat-panel system offers superior image quality to that of screen-film and storage-phosphor systems.
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Figure 3c. Radiographs of the lumbar spine obtained with (a) the speed class 400 screen-film system; the flat-panel system at exposure doses equivalent to speed classes (b) 400, (c) 800, and (d) 1600; and the storage-phosphor system at exposure doses equivalent to speed classes (e) 400, (f) 800, and (g) 1600. The flat-panel system offers superior image quality to that of screen-film and storage-phosphor systems.
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Figure 3d. Radiographs of the lumbar spine obtained with (a) the speed class 400 screen-film system; the flat-panel system at exposure doses equivalent to speed classes (b) 400, (c) 800, and (d) 1600; and the storage-phosphor system at exposure doses equivalent to speed classes (e) 400, (f) 800, and (g) 1600. The flat-panel system offers superior image quality to that of screen-film and storage-phosphor systems.
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Figure 3e. Radiographs of the lumbar spine obtained with (a) the speed class 400 screen-film system; the flat-panel system at exposure doses equivalent to speed classes (b) 400, (c) 800, and (d) 1600; and the storage-phosphor system at exposure doses equivalent to speed classes (e) 400, (f) 800, and (g) 1600. The flat-panel system offers superior image quality to that of screen-film and storage-phosphor systems.
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Figure 3f. Radiographs of the lumbar spine obtained with (a) the speed class 400 screen-film system; the flat-panel system at exposure doses equivalent to speed classes (b) 400, (c) 800, and (d) 1600; and the storage-phosphor system at exposure doses equivalent to speed classes (e) 400, (f) 800, and (g) 1600. The flat-panel system offers superior image quality to that of screen-film and storage-phosphor systems.
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Figure 3g. Radiographs of the lumbar spine obtained with (a) the speed class 400 screen-film system; the flat-panel system at exposure doses equivalent to speed classes (b) 400, (c) 800, and (d) 1600; and the storage-phosphor system at exposure doses equivalent to speed classes (e) 400, (f) 800, and (g) 1600. The flat-panel system offers superior image quality to that of screen-film and storage-phosphor systems.
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Figure 4a. Detail magnifications of radiographs obtained with (a) the speed class 400 screen-film system; the flat-panel system at exposure doses equivalent to speed classes (b) 400, (c) 800, and (d) 1600; and the storage-phosphor system at exposure doses equivalent to speed classes (e) 400, (f) 800, and (g) 1600. With identical exposure dose, the flat-panel system offers the best depiction of anatomic structures. With both digital imaging systems, depiction of anatomic structures deteriorates with decreasing exposure dose.
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Figure 4b. Detail magnifications of radiographs obtained with (a) the speed class 400 screen-film system; the flat-panel system at exposure doses equivalent to speed classes (b) 400, (c) 800, and (d) 1600; and the storage-phosphor system at exposure doses equivalent to speed classes (e) 400, (f) 800, and (g) 1600. With identical exposure dose, the flat-panel system offers the best depiction of anatomic structures. With both digital imaging systems, depiction of anatomic structures deteriorates with decreasing exposure dose.
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Figure 4c. Detail magnifications of radiographs obtained with (a) the speed class 400 screen-film system; the flat-panel system at exposure doses equivalent to speed classes (b) 400, (c) 800, and (d) 1600; and the storage-phosphor system at exposure doses equivalent to speed classes (e) 400, (f) 800, and (g) 1600. With identical exposure dose, the flat-panel system offers the best depiction of anatomic structures. With both digital imaging systems, depiction of anatomic structures deteriorates with decreasing exposure dose.
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Figure 4d. Detail magnifications of radiographs obtained with (a) the speed class 400 screen-film system; the flat-panel system at exposure doses equivalent to speed classes (b) 400, (c) 800, and (d) 1600; and the storage-phosphor system at exposure doses equivalent to speed classes (e) 400, (f) 800, and (g) 1600. With identical exposure dose, the flat-panel system offers the best depiction of anatomic structures. With both digital imaging systems, depiction of anatomic structures deteriorates with decreasing exposure dose.
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Figure 4e. Detail magnifications of radiographs obtained with (a) the speed class 400 screen-film system; the flat-panel system at exposure doses equivalent to speed classes (b) 400, (c) 800, and (d) 1600; and the storage-phosphor system at exposure doses equivalent to speed classes (e) 400, (f) 800, and (g) 1600. With identical exposure dose, the flat-panel system offers the best depiction of anatomic structures. With both digital imaging systems, depiction of anatomic structures deteriorates with decreasing exposure dose.
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Figure 4f. Detail magnifications of radiographs obtained with (a) the speed class 400 screen-film system; the flat-panel system at exposure doses equivalent to speed classes (b) 400, (c) 800, and (d) 1600; and the storage-phosphor system at exposure doses equivalent to speed classes (e) 400, (f) 800, and (g) 1600. With identical exposure dose, the flat-panel system offers the best depiction of anatomic structures. With both digital imaging systems, depiction of anatomic structures deteriorates with decreasing exposure dose.
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Figure 4g. Detail magnifications of radiographs obtained with (a) the speed class 400 screen-film system; the flat-panel system at exposure doses equivalent to speed classes (b) 400, (c) 800, and (d) 1600; and the storage-phosphor system at exposure doses equivalent to speed classes (e) 400, (f) 800, and (g) 1600. With identical exposure dose, the flat-panel system offers the best depiction of anatomic structures. With both digital imaging systems, depiction of anatomic structures deteriorates with decreasing exposure dose.
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Statistical analysis results obtained by using the Friedman test showed that the mean scores for the flat-panel system at speed classes 400 and 800 were significantly lower (lower scores indicated better visibility) than those of the screen-film system at speed class 400 and the storage-phosphor system at speed classes 400, 800, and 1600 (P < .05).
Mean scores for all anatomic details and for each of the readers are listed in the Table.
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DISCUSSION
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To our knowledge, eight articles have been published on clinical studies of image quality and exposure dose requirements of direct read-out flat-panel detector systems (10–17). In all of these studies, adult patients were examined. Chest images were assessed in five studies (13–17), and skeletal images were assessed in the remaining three (10–12).
In an early study, Strotzer et al examined 120 patients with a speed class 400 screen-film system and a small-area prototype flat-panel system by using different exposure doses (10). Examinations performed in this study included many anatomic areas, such as the head, spine, pelvis and hip, extremities, and ribs. In one-third of examinations, metallic implants were present; some patients wore casts. Different tube voltages were used for the different anatomic areas. Because of the smaller field of the prototype detector (15 x 15 cm), collimation was smaller for the flat-panel images, which affects the amount of scatter radiation on the images. The authors state that on the basis of their calculations, however, differences in scatter radiation did not relevantly affect their results. In their rather heterogeneous set of examinations, flat-panel images were rated slightly superior for all examined aspects at an equal exposure dose, except for the criterion of contrast resolution. For lower exposure doses with the flat-panel system, assessments were unequivocal.
In another study, Volk et al compared a speed class 400 screen-film system with a flat-panel system used at speed classes 400, 800, and 1600 in 30 patients (11). Images of the spine, pelvis and hip, extremities, ribs, and clavicles were obtained with different tube voltages and compared. The flat-panel system was rated superior to the screen-film system at equal exposure dose, equal when used equivalent to a speed class 800 system, and inferior when used equivalent to a speed class 1600 system.
A third clinical study was performed by Hamers et al in 24 patients who underwent radiation therapy (12). Thirty image pairs of different anatomic areas were acquired in these patients with screen-film and flat-panel systems with identical exposure dose. The flat-panel system was rated as superior to the screen-film system.
In contrast to the studies mentioned earlier, we compared imaging systems with a single type of examination, that of the lumbar spine, which results in more homogeneous data. We used the same tube voltage for all examinations. This is of special importance in the assessment of exposure dose requirements of imaging systems, because x-ray sensitivity with flat-panel systems depends on tube voltage.
Another difference from the other studies mentioned is that we compared three imaging systems with each other and used three exposure dose levels with both of the digital systems. Furthermore, the mean size and weight of the monkeys in our study were equivalent to those of infants between 3 and 4 months of age so that all images were acquired with absorption and scatter radiation conditions similar to those in pediatric patients of this age (18).
We believe that this study is important for two reasons: First, little is known about differences between screen-film, flat-panel, and storage-phosphor systems with regard to sensitivity for scatter radiation. For indirect-type flat-panel detectors, a light-channeling function of structured scintillators, such as cesium iodide, has been suggested (19). The scintillator layer of a flat-panel system is considerably thicker than that of a screen-film system, however. To our knowledge, exact measurements of scatter radiation sensitivity have not been published. Second, with screen-film systems, scatter radiation results in a reduction of contrast, while with most digital systems with modern postprocessing algorithms, image contrast can be enhanced so that scatter radiation results in an increase of image noise that is enhanced, as well. Therefore, to make a valid statement on exposure dose reduction in pediatric patients with use of flat-panel systems, examinations should be performed to simulate the amount of scatter radiation present in a specific type of pediatric examination.
Although we examined only 20 animals, with our specific image evaluation process we tried to avoid dependence of observations on different anatomic details. For our statistical evaluation, we considered these observations to be independent. This assumption can be taken as a limitation of our study. Our data show that for radiography of the lumbar spine in monkeys as a pediatric model, the flat-panel system provides superior image quality to that with screen-film and storage-phosphor systems at an equal exposure dose. Our data also show that an exposure dose reduction of 75% is possible with an image quality equivalent to that with a normally exposed speed class 400 screen-film or storage-phosphor system.
Practical application: We conclude from our data that in pediatric spinal radiography, an exposure dose reduction of 75% seems possible without loss of image quality when a flat-panel system is used instead of a screen-film or storage-phosphor system. Additionally, superior image quality can be achieved when a flat-panel system is used with the exposure dose required for a speed class 400 screen-film system.
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FOOTNOTES
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Author contributions: Guarantor of integrity of entire study, K.L.; study concepts and design, K.L.; literature research, W.H.; clinical studies, K.A.; experimental studies, D.W.; data acquisition, K.A.; data analysis/interpretation, M.F.; statistical analysis, T.M.B.; manuscript preparation and definition of intellectual content, S.D.; manuscript editing, K.L.; manuscript revision/review and final version approval, K.L., W.H.
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REFERENCES
|
|---|
- Siewerdsen JH, Antonuk LE, El-Mohri Y, Yorkston J, Huang W, Cunningham IA. Signal, noise power spectrum, and detective quantum efficiency of indirect-detection flat-panel imagers for diagnostic radiology. Med Phys 1998; 25:614-628.[CrossRef][Medline]
- Granfors PR, Aufrichtig R. Performance of a 41 x 41-cm2 amorphous silicon flat panel x-ray detector for radiographic imaging applications. Med Phys 2000; 27:1324-1331.[CrossRef][Medline]
- Andriole KP, Gould RG, Luth DM. Workflow comparison of DR and screen-film dedicated chest systems. Proc SPIE 2001; 4323:203-206.[CrossRef]
- Spahn M, Strotzer M, Volk M, et al. Digital radiography with a large-area, amorphous-silicon, flat-panel x-ray detector system. Invest Radiol 2000; 35:260-266.[CrossRef][Medline]
- Floyd CE, Warp RJ, Dobbins JT, et al. Imaging characteristics of an amorphous silicon flat-panel detector for digital chest radiography. Radiology 2001; 218:683-688.[Abstract/Free Full Text]
- Ludwig K, Lenzen H, Kamm KF, et al. Performance of a flat-panel detector in detecting artificial bone lesions: comparison with conventional screen-film and storage-phosphor radiography. Radiology 2002; 222:453-459.[Abstract/Free Full Text]
- Strotzer M, Gmeinwieser JK, Volk M, Frund R, Seitz J, Feuerbach S. Detection of simulated chest lesions with normal and reduced radiation dose: comparison of conventional screen-film radiography and a flat-panel x-ray detector based on amorphous silicon. Invest Radiol 1998; 33:98-103.[CrossRef][Medline]
- Strotzer M, Gmeinwieser J, Spahn M, et al. Amorphous silicon, flat-panel, x-ray detector versus screen-film radiography: effect of dose reduction on the detectability of cortical bone defects and fractures. Invest Radiol 1998; 33:33-38.[CrossRef][Medline]
- Strotzer M, Volk M, Wild T, von Landenberg P, Feuerbach S. Simulated bone erosions in a hand phantom: detection with conventional screen-film technology versus cesium iodide-amorphous silicon flat-panel detector. Radiology 2000; 215:512-515.[Abstract/Free Full Text]
- Strotzer M, Gmeinwieser J, Volk M, et al. Clinical application of a flat-panel x-ray detector based on amorphous silicon technology: image quality and potential for radiation dose reduction in skeletal radiography. AJR Am J Roentgenol 1998; 171:23-27.[Abstract/Free Full Text]
- Volk M, Strotzer M, Holzknecht N, et al. Digital radiography of the skeleton using a large-area detector based on amorphous silicon technology: image quality and potential for exposure dose reduction in comparison with screen-film radiography. Clin Radiol 2000; 55:615-621.[CrossRef][Medline]
- Hamers S, Freyschmidt J, Neitzel U. Digital radiography with a large-scale electronic flat-panel detector vs screen-film radiography: observer preference in clinical skeletal diagnostics. Eur Radiol 2001; 11:1753-1759.[CrossRef][Medline]
- Garmer M, Hennigs SP, Jager HJ, et al. Digital radiography versus conventional radiography in chest imaging: diagnostic performance of a large-area silicon flat-panel detector in a clinical CT-controlled study. AJR Am J Roentgenol 2000; 174:75-80.[Abstract/Free Full Text]
- Fink C, Hallscheidt PJ, Noeldge G, et al. Clinical comparative study with a large-area amorphous silicon flat-panel detector: image quality and visibility of anatomic structures on chest radiography. AJR Am J Roentgenol 2002; 178:481-486.[Abstract/Free Full Text]
- Hennigs SP, Garmer M, Jaeger HJ, et al. Digital chest radiography with a large-area flat-panel silicon x-ray detector: clinical comparison with conventional radiography. Eur Radiol 2001; 11:1688-1696.[CrossRef][Medline]
- Strotzer M, Volk M, Frund R, Hamer O, Zorger N, Feuerbach S. Routine chest radiography using a flat-panel detector: image quality at standard detector dose and 33% dose reduction. AJR Am J Roentgenol 2002; 178:169-171.[Abstract/Free Full Text]
- Herrmann A, Bonel S, Stabler A, et al. Chest imaging with flat-panel detector at low and standard doses: comparison with storage-phosphor technology in normal patients. Eur Radiol 2002; 12:385-390.[CrossRef][Medline]
- Brandt I. Grow dynamics of low-birthweight infants with emphasis on the perinatal period. In: Falkner F, Tanner JM, eds. Human growth: a comprehensive treatise. 2nd ed. Vol 1. New York, NY: Plenum, 1986.
- Chotas HG, Dobbins JT, Ravin CE. Principles of digital radiography with large-area electronically readable detectors: a review of the basics. Radiology 1999; 210:595-599.[Free Full Text]
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ABSTRACT
INTRODUCTION
