- Email: [email protected]
Digital imaging of the newborn chest
Clinical Radiology (1989) 40, 365-368
Digital Imaging of the Newborn Chest M. D. COHEN, B. LONG, D. A. CORY, N. J. B R O D E R I C K and J. A. SMITH
Department of Radiology, James Whitcomb Riley Hospital for Children, Indiana University School of Medicine, Indianopolis, IN 46223, USA The study reports initial experience on utilising an area plate digital imaging system to obtain portable radiographic images on newborn infants. Initial results suggest that the system is a practical alternative to conventional portable radiography with potential advantages of decreasing the number of retake films and also of decreasing radiation dose.
Digital imaging offers the potential advantages of dose reduction, electronic image transfer, and image manipulation to enhance diagnosis (Kastan et al., 1985; Smathers and Brody, 1985). There is relatively little experience utilising digital imaging techniques for conventional radiography. This study reports our initial experience using an area plate digital radiographic system to obtain over 1500 digital images of newborn infants. The objectives of the study were not to obtain a critical comparison with conventional images, but rather to see if utilisation of a digital system was practical in a busy clinical setting, to determine if images of adequate quality could be obtained, and to attempt to optimise image processing algorithms. MATERIALS AND M E T H O D S The study utilised a digital imaging system supplied by Philips Medical Imaging. X-ray film and the intensifying screens are replaced in the X-ray cassette with an imaging plate. This plate is composed of barium fluoro halide. The imaging plate, within the cassette, is exposed to radiation in the conventional manner. We used a General Electric AMX portable unit to make the radiographic exposures. The plate and cassette are then taken to the X-ray department. The imaging plate is automatically unloaded from the cassette. The latent image stored in the plate is released by scanning the plate in a 2510x2510 pixel matrix, with a red laser beam. The laser 'unlocks' the stored energy from each pixel in turn, capturing the information in a digital form. Pixel size is approximately 0.1 mm. The digital images are then processed and transferred on to film for final viewing. The image processing is complex and involves control of seven different variables, affecting the shape, position, and slope of the H and D curve and also the amount of edge enhancement, and the size of structure to be maximally enhanced. For routine use the image processing algorithms are preprogrammed so that image processing occurs automatically. All the raw digital data is stored on optical laser disc so that, for research purposes, images can be reprocessed changing one or more of the image processing parameters on each occasion. In order to explore the potential for image manipulaOffprintrequests to: M. D. Cohen, Department of Radiology,Riley Hospital for Children,BarnhillDrive, Indianapolis,IN 46223, USA.
tion, sets of images were generated varying a single processing factor throughout its complete range of possible settings. This was repeated for each processing parameter. Initially, automatic image processing was done utilising predefined protocols supplied by Philips imaging. These were subsequently slightly modified based on the results of our own image processing experiment. No specific patient selection criteria were applied, apart from the fact that all the patients were sick infants in our tertiary care newborn nursery. This nursery has 48 beds so that a high volume of portable newborn radiographs is performed each day. Initially, only a few patients were studied, using the digital system. Numbers were subsequently increased so that at the present time most portable daytime radiographs are obtained using the digital system. During evenings and weekends conventional imaging is still utilised. Thus, as many infants require multiple radiographs, comparative studies are available using both conventional and digital imaging in the same infant. Our conventional radiographic system uses Kevlar cassettes (Dupont) and a film screen combination (Dupont SR 347 screen and Cronex 7 film) with a speed of approximately 300. The radiographic exposure utilised for most of the digital images was the same as that which would be utilised for the conventional film screen combination. In some patients, however, we deliberately chose to reduce the exposure, decreasing the MAS by between 25 and 50%, or decreasing the KVP by 5. RESULTS The system can routinely produce high-quality images and our initial subjective impression is that the diagnostic information is equivalent to conventional images (Figs 13). The system is capable of coping easily with the entire load of our newborn nursery of 48 beds, without any major delays in image processing and throughput. The entire processing sequence takes approximately 3 min from the time that the imaging plate is inserted into the processor to the time that the final film is obtained. The system is simple to use and is virtually automatic. The system has been extremely reliable with little down time. Processing algorithms have been little changed as a result of our reprocessing studies. The one change made has been a slight reduction in the amount of edge enhancement. Reduction of MAS by 25-33% for the digital images resulted in images judged subjectively to be similar to higher dose conventional images in the same patient (Fig. 1). Initial impressions are that the diagnostic information from the heart and lungs is roughly equivalent to that obtained with the conventional radiograph (Fig. 1). The visualisation of bones, and particularly of soft tissue, appears to be better on the digital images (Figs 2 and 3). In addition, the outline of endotracheal tubes and
366
CLINICAL RADIOLOGY
(a)
(b)
Fig. 1 - Dose reduction. Five-day-old infant with mild hyaline membrane disease. (a) Conventional image is obtained with KVP 65, MAS 1. (b) Digital image obtained a few hours earlier with KVP 60, MAS 1.
Ib) (a)
(~)
Fig. 2 - Edge enhancement and soft tissue visualisation. (a) Conventional, (b) digital and (c) edge-enhanced digital image are shown. The patient recently had surgical switching of the great vessels for transposition. Note the markedly improved visualisation of the soft tissues on digital image. The edge enhanced image sharpens the visualisation of the catheters, tubes and wires, and also of the bone edges.
DIGITAL IMAGING OF THE NEWBORN CHEST
367
catheters can be enhanced with the digital imaging system (Fig. 2). The number of repeat radiographs taken for exposure, and not positioning errors, has been reduced almost to zero. The major difficulty encountered in operation of the system is that during image processing the edges of the cones need to be recognised. In order for the system to do this the cones must be relatively parallel to the edges of the cassette. Significant deviation from this results in inaccurate localisation of the cone edges and subsequent darkening of the radiograph. The radiograph can be reprocessed to achieve an image of normal density, but this requires that the technician manually reprocess the particular image. DISCUSSION
(a)
(b)
(c)
Radiologists are now accustomed to digital imaging, which however has been largely confined to specialised techniques such as computed tomography, magnetic resonance and ultrasound. Recently there have been a few reports of the utilisation of digital imaging systems for conventional radiography (Alotis, 1984; Sartoris and Sommer, 1984; Merritt, 1985; Merritt et al., 1985; Doi et al., 1986; Fajardo et al., 1987; Kushner et al., 1986; Nakano et al., 1986; Nakano et al., 1987; Kogutt, 1987; Wilson and Ramsby, 1987). There have also been reports of digital imaging of the chest in adults (Fraser et al., 1983; Barnes et al., 1985; Goodman et al., 1986; MacMahon et al., 1986). Several methods are available for obtaining digital chest radiographs (Kastan et al., 1985). The first method utilises a laser beam to scan a conventionally acquired chest radiograph (Lams and Cocklin, 1986; MacMahon et al., 1986). Whilst digital images can be obtained in this manner, it is somewhat slow and cumbersome and does require that a conventional radiograph be obtained first. The second method utilises a pencil or fan beam to scan across the patient (Sashin and Sternglass, 1983). A detector is placed behind the patient (Fraser et al., 1983). This type of system is slow, requiring between 4 and 6 s/ exposure. It also requires the use of dedicated equipment and therefore cannot be utilised for portable radiographic studies. Spatial resolution is a limiting factor with this system. Our digital imaging system makes use of conventional radiographic equipment. This has two advantages. Firstly, our technicians are familiar with the existing equipment and can use it to obtain portable radiographs. Secondly, if the digital system is down for maintenance, then conventional images can easily be obtained. Although there are a large number of processing algorithms which can be applied to the images, the system is so designed that these imaging parameters can be preselected. This means that for routine use the entire system is automated and functions rather like a conventional imaging system in that a cassette is automatically
Fig. 3 - Pneumothorax. There is a large right pneumothorax. It is well seen on (a) the conventional image, (b) digital image and (c) edgeenhanced digital image. Note the improved visibility of the pleurat margin on the edge enhanced image. Images all obtained with same exposure. There were 2 h between image (a) and images (b) and (e).
368
CLINICAL RADIOLOGY
unloaded into a processing system and an image automatically a p p e a r s o n film at t h e o t h e r end. T h e o n l y d i f f e r e n c e b e t w e e n o u r s y s t e m a n d the c o n v e n t i o n a l s y s t e m is t h a t the i m a g e p r o c e s s i n g t a k e s a p p r o x i m a t e l y 3 m i n as o p p o s e d to 90 s f o r a c o n v e n t i o n a l r a d i o g r a p h . O u r s t u d y i n d i c a t e s t h a t it is p o s s i b l e to o b t a i n h i g h q u a l i t y r a d i o g r a p h s u s i n g a d i g i t a l i m a g i n g system. P o t e n t i a l a d v a n t a g e s a r e the d e c r e a s e in X - r a y dose, the p o s s i b i l i t y o f i n c r e a s i n g d i a g n o s t i c i n f o r m a t i o n by i m a g e m a n i p u l a t i o n , a n d the p o t e n t i a l f o r t r a n s f e r r i n g i m a g e s to v i e w i n g m o n i t o r s l o c a t e d in t h e n e w b o r n n u r s e r y . O n e d i s a d v a n t a g e o f digital i m a g i n g is t h a t t h e r e is a fairly s u b s t a n t i a l c a p i t a l cost i n v o l v e d to p u r c h a s e the e q u i p m e n t . H o w e v e r , o n c e t h e e q u i p m e n t is installed, o p e r a t i o n costs are n o m o r e t h a n f o r c o n v e n t i o n a l r a d i o g r a p h y ; in f a c t in s o m e s i t u a t i o n s , i m a g e m a g n i f i c a t i o n c a n result in a t o t a l s a v i n g in film cost. F u t u r e studies wilt report detailed comparative analyses between conventional a n d digital i m a g e s in the n e w b o r n c h e s t to m o r e specifically e v a l u a t e the p o t e n t i a l o f digital i m a g i n g for d e t e c t i o n o f b o t h n o r m a l a n d p a t h o l o g i c a l tissues. W e also p l a n to e v a l u a t e t h e a c c u r a c y o f d i a g n o s i s o f f the r e m o t e m o n i t o r s l o c a t e d in the n e w b o r n i n t e n s i v e c a r e a r e a , w h e n c o m p a r e d to d i a g n o s i s m a d e off the h a r d c o p y film. REFERENCES
Alotis, MA (1984). Digital radiographic studies of the esophagus and upper GI tract. RNM Images May/Jun, 32 34. Barnes, GT, Scones, RA & Tesic, MM (1985). Digital chest radiography: Performance evaluation of a prototype unit. Radiology, 154, 801-806. Doi, K, Fujita, H, Ohara, K, Ono, K, Matsui, H, Giger, ML et al. (1986). Digital radiographic imaging system with multiple-slit scanning x-ray beam: Preliminary report. Radiology, 161, 513 518. Fajardo, LL, Hillman, BJ, Hunter, TB, Claypool, HR. Westerman, BR & Mockbee, B (1987). Excretory urography using computed radiography. Radiology, 162, 345 351.
Fraser, RG, Breatnach, E & Barnes, GT (1983). Digital radiography of the chest: Clinical experience with a prototype unit. Radiology, 148, 15. Goodman, LR, Foley, WD, Wilson, CR, Rimm, AA & Lawson, TL (1986). Digital and conventional chest images: observer performance with film digital radiography system. Radiology, 158, 27-33. Kastan, DJ, Ackerman, LV, Feczko, PJ & Beute, GH (1985). Digital radiography: A review. Henry Ford Hospital Medical Journal, 33, 88-94. Kogutt, MS (1987). Computed radiographic imaging: Use in low dose leg length radiography. American Journal of Roentgenology, 148, 1205 1206. Kushner, DC, Cleveland, RH, Herman, TE, Zaleske, D J, Ehrlich, MG & Correia, JA (1986). Radiation dose reduction in the evaluation of scoliosis: An application of digital radiography. Radiology, 161, 174-181. Lares, PM & Cocklin, ML (1986). Spatial resolution requirements for digital chest radiographs: An ROC study of observer performance in selected cases. Radiology, 158, 11 19. MacMahon, H, Vyborny, C J, Metz, CE, Doi, K, Sabeni, V & Solomon, SL (1986). Digital radiography of subtle pulmonary abnormalities: An ROC study of the effect of pixel size on observer performance. Radiology, 158, 21 26. Merritt, CRB (1985). Computed radiography: A new approach to plain film imaging. Diagnostic Imaging, 7, 58 65. Merritt, CRB, Matthews, CC, Tutton, RH, Miller, KD, Belt, KA, Kogutt, MS et al. (1985). Clinical application of digital radiography: Computed radiographic imaging. RadioGraphics, 5, 397-414. Nakano, Y, Togashi, K, Nishimura, K, Itoh, K, Fujisawa, I, Asato, T et al. (1986). Stomach and duodenum: Radiographic magnification using computed radiography (CR). Radiology, 160, 383-387. Nakano, Y, Hiraoka, T, Togoshi, K, Nishimura, K, Itoh, K, Fujisawa, I et aL (1987). Direct radiographic magnification with computed radiography. American Journal of Roentgenology, 148, 569 573. Sartoris, DJ & Sommer, FG (1984). Digital film processing: Applications to the musculoskeletal system. Skeletal Radiology, 11, 274 281. Sashin, D & Sterngtass, EJ (1983). Approaching radiology's theoretical limits. Diagnostic Imaging, 5, 126-131. Smathers, RL & Brody, WR (1985). Digital radiography: Current and future trends. British Journal of Radiology, 58, 285-307. Wilson, AJ & Ramsby, GR (1987). Skeletal measurements using a flying spot digital imaging device. American Journal of Roentgenology, 149, 339-343.
Book Review Radiology- Practical Guides for General Practice 3. By R. F. Bury.
Oxford University Press, Oxford, 1988.96 pp., £4.50. This short book is one in a series providing practical guides on important topics for general practitioners. The aim of this volume is to enable the GP to choose the right examination, prepare the patient, and make sense of the result, also to explain the role of new techniques which will not be available on open access to GPs. The book js divided into four sections. The first section deals with the relationship between the radiologist and GP and contains much common-sense, but advice on how one should 'correct any bad referral habits' is not given. The second section deals with the hazards of diagnostic imaging and these are clearly presented. The 28 day rule is explained: an example of a pregnancy disclaimer form is included. Many women will realise that they cannot be absolutely sure they are not pregnant and the procedure to be followed in this case is not clarified. The third section is an account of imaging in the 80s, describing plain film radiography, fluoroscopy, DVI, CT, US, nuclear medicine and MRI. The descriptions are simple and clear, an outline of the applications of CT and US is given. CT is suggested for obscure abdominal masses not resolved by other means; many radiologists
would argue it should be the first investigation not the last. There are pictures of radiographic equipment in use which are helpful apart from the picture of the CT scanner, which is not very clear. A solitary MRI image is reproduced which does nothing to demonstrate what is possible with this technique. The remainder, and major part, of the book is devoted to a system by system account of investigations, giving indications, patient preparation and a description of the procedure, and some advice on interpreting the result. The advice is dogmatic and sound. The merits of the barium meal versus endoscopy and the oral cholecystogram versus ultrasound are briefly discussed. Sialography and cerebral angiography merit brief descriptions but peripheral angiography does not. Many radiologists will not share the author's enthusiasm for an open access barium enema service. Overall this book achieves its aims very well and covers much ground very concisely and clearly. It deserves to be widely read and should be strongly recommended to any GP seeking to make the best use of the radiology department. For radiologists it provides all the material necessary to prepare the lectures for GPs that the author suggests radiologists should give at their postgraduate centre. E. Barton
Digital Imaging of the Newborn Chest M. D. COHEN, B. LONG, D. A. CORY, N. J. B R O D E R I C K and J. A. SMITH
Department of Radiology, James Whitcomb Riley Hospital for Children, Indiana University School of Medicine, Indianopolis, IN 46223, USA The study reports initial experience on utilising an area plate digital imaging system to obtain portable radiographic images on newborn infants. Initial results suggest that the system is a practical alternative to conventional portable radiography with potential advantages of decreasing the number of retake films and also of decreasing radiation dose.
Digital imaging offers the potential advantages of dose reduction, electronic image transfer, and image manipulation to enhance diagnosis (Kastan et al., 1985; Smathers and Brody, 1985). There is relatively little experience utilising digital imaging techniques for conventional radiography. This study reports our initial experience using an area plate digital radiographic system to obtain over 1500 digital images of newborn infants. The objectives of the study were not to obtain a critical comparison with conventional images, but rather to see if utilisation of a digital system was practical in a busy clinical setting, to determine if images of adequate quality could be obtained, and to attempt to optimise image processing algorithms. MATERIALS AND M E T H O D S The study utilised a digital imaging system supplied by Philips Medical Imaging. X-ray film and the intensifying screens are replaced in the X-ray cassette with an imaging plate. This plate is composed of barium fluoro halide. The imaging plate, within the cassette, is exposed to radiation in the conventional manner. We used a General Electric AMX portable unit to make the radiographic exposures. The plate and cassette are then taken to the X-ray department. The imaging plate is automatically unloaded from the cassette. The latent image stored in the plate is released by scanning the plate in a 2510x2510 pixel matrix, with a red laser beam. The laser 'unlocks' the stored energy from each pixel in turn, capturing the information in a digital form. Pixel size is approximately 0.1 mm. The digital images are then processed and transferred on to film for final viewing. The image processing is complex and involves control of seven different variables, affecting the shape, position, and slope of the H and D curve and also the amount of edge enhancement, and the size of structure to be maximally enhanced. For routine use the image processing algorithms are preprogrammed so that image processing occurs automatically. All the raw digital data is stored on optical laser disc so that, for research purposes, images can be reprocessed changing one or more of the image processing parameters on each occasion. In order to explore the potential for image manipulaOffprintrequests to: M. D. Cohen, Department of Radiology,Riley Hospital for Children,BarnhillDrive, Indianapolis,IN 46223, USA.
tion, sets of images were generated varying a single processing factor throughout its complete range of possible settings. This was repeated for each processing parameter. Initially, automatic image processing was done utilising predefined protocols supplied by Philips imaging. These were subsequently slightly modified based on the results of our own image processing experiment. No specific patient selection criteria were applied, apart from the fact that all the patients were sick infants in our tertiary care newborn nursery. This nursery has 48 beds so that a high volume of portable newborn radiographs is performed each day. Initially, only a few patients were studied, using the digital system. Numbers were subsequently increased so that at the present time most portable daytime radiographs are obtained using the digital system. During evenings and weekends conventional imaging is still utilised. Thus, as many infants require multiple radiographs, comparative studies are available using both conventional and digital imaging in the same infant. Our conventional radiographic system uses Kevlar cassettes (Dupont) and a film screen combination (Dupont SR 347 screen and Cronex 7 film) with a speed of approximately 300. The radiographic exposure utilised for most of the digital images was the same as that which would be utilised for the conventional film screen combination. In some patients, however, we deliberately chose to reduce the exposure, decreasing the MAS by between 25 and 50%, or decreasing the KVP by 5. RESULTS The system can routinely produce high-quality images and our initial subjective impression is that the diagnostic information is equivalent to conventional images (Figs 13). The system is capable of coping easily with the entire load of our newborn nursery of 48 beds, without any major delays in image processing and throughput. The entire processing sequence takes approximately 3 min from the time that the imaging plate is inserted into the processor to the time that the final film is obtained. The system is simple to use and is virtually automatic. The system has been extremely reliable with little down time. Processing algorithms have been little changed as a result of our reprocessing studies. The one change made has been a slight reduction in the amount of edge enhancement. Reduction of MAS by 25-33% for the digital images resulted in images judged subjectively to be similar to higher dose conventional images in the same patient (Fig. 1). Initial impressions are that the diagnostic information from the heart and lungs is roughly equivalent to that obtained with the conventional radiograph (Fig. 1). The visualisation of bones, and particularly of soft tissue, appears to be better on the digital images (Figs 2 and 3). In addition, the outline of endotracheal tubes and
366
CLINICAL RADIOLOGY
(a)
(b)
Fig. 1 - Dose reduction. Five-day-old infant with mild hyaline membrane disease. (a) Conventional image is obtained with KVP 65, MAS 1. (b) Digital image obtained a few hours earlier with KVP 60, MAS 1.
Ib) (a)
(~)
Fig. 2 - Edge enhancement and soft tissue visualisation. (a) Conventional, (b) digital and (c) edge-enhanced digital image are shown. The patient recently had surgical switching of the great vessels for transposition. Note the markedly improved visualisation of the soft tissues on digital image. The edge enhanced image sharpens the visualisation of the catheters, tubes and wires, and also of the bone edges.
DIGITAL IMAGING OF THE NEWBORN CHEST
367
catheters can be enhanced with the digital imaging system (Fig. 2). The number of repeat radiographs taken for exposure, and not positioning errors, has been reduced almost to zero. The major difficulty encountered in operation of the system is that during image processing the edges of the cones need to be recognised. In order for the system to do this the cones must be relatively parallel to the edges of the cassette. Significant deviation from this results in inaccurate localisation of the cone edges and subsequent darkening of the radiograph. The radiograph can be reprocessed to achieve an image of normal density, but this requires that the technician manually reprocess the particular image. DISCUSSION
(a)
(b)
(c)
Radiologists are now accustomed to digital imaging, which however has been largely confined to specialised techniques such as computed tomography, magnetic resonance and ultrasound. Recently there have been a few reports of the utilisation of digital imaging systems for conventional radiography (Alotis, 1984; Sartoris and Sommer, 1984; Merritt, 1985; Merritt et al., 1985; Doi et al., 1986; Fajardo et al., 1987; Kushner et al., 1986; Nakano et al., 1986; Nakano et al., 1987; Kogutt, 1987; Wilson and Ramsby, 1987). There have also been reports of digital imaging of the chest in adults (Fraser et al., 1983; Barnes et al., 1985; Goodman et al., 1986; MacMahon et al., 1986). Several methods are available for obtaining digital chest radiographs (Kastan et al., 1985). The first method utilises a laser beam to scan a conventionally acquired chest radiograph (Lams and Cocklin, 1986; MacMahon et al., 1986). Whilst digital images can be obtained in this manner, it is somewhat slow and cumbersome and does require that a conventional radiograph be obtained first. The second method utilises a pencil or fan beam to scan across the patient (Sashin and Sternglass, 1983). A detector is placed behind the patient (Fraser et al., 1983). This type of system is slow, requiring between 4 and 6 s/ exposure. It also requires the use of dedicated equipment and therefore cannot be utilised for portable radiographic studies. Spatial resolution is a limiting factor with this system. Our digital imaging system makes use of conventional radiographic equipment. This has two advantages. Firstly, our technicians are familiar with the existing equipment and can use it to obtain portable radiographs. Secondly, if the digital system is down for maintenance, then conventional images can easily be obtained. Although there are a large number of processing algorithms which can be applied to the images, the system is so designed that these imaging parameters can be preselected. This means that for routine use the entire system is automated and functions rather like a conventional imaging system in that a cassette is automatically
Fig. 3 - Pneumothorax. There is a large right pneumothorax. It is well seen on (a) the conventional image, (b) digital image and (c) edgeenhanced digital image. Note the improved visibility of the pleurat margin on the edge enhanced image. Images all obtained with same exposure. There were 2 h between image (a) and images (b) and (e).
368
CLINICAL RADIOLOGY
unloaded into a processing system and an image automatically a p p e a r s o n film at t h e o t h e r end. T h e o n l y d i f f e r e n c e b e t w e e n o u r s y s t e m a n d the c o n v e n t i o n a l s y s t e m is t h a t the i m a g e p r o c e s s i n g t a k e s a p p r o x i m a t e l y 3 m i n as o p p o s e d to 90 s f o r a c o n v e n t i o n a l r a d i o g r a p h . O u r s t u d y i n d i c a t e s t h a t it is p o s s i b l e to o b t a i n h i g h q u a l i t y r a d i o g r a p h s u s i n g a d i g i t a l i m a g i n g system. P o t e n t i a l a d v a n t a g e s a r e the d e c r e a s e in X - r a y dose, the p o s s i b i l i t y o f i n c r e a s i n g d i a g n o s t i c i n f o r m a t i o n by i m a g e m a n i p u l a t i o n , a n d the p o t e n t i a l f o r t r a n s f e r r i n g i m a g e s to v i e w i n g m o n i t o r s l o c a t e d in t h e n e w b o r n n u r s e r y . O n e d i s a d v a n t a g e o f digital i m a g i n g is t h a t t h e r e is a fairly s u b s t a n t i a l c a p i t a l cost i n v o l v e d to p u r c h a s e the e q u i p m e n t . H o w e v e r , o n c e t h e e q u i p m e n t is installed, o p e r a t i o n costs are n o m o r e t h a n f o r c o n v e n t i o n a l r a d i o g r a p h y ; in f a c t in s o m e s i t u a t i o n s , i m a g e m a g n i f i c a t i o n c a n result in a t o t a l s a v i n g in film cost. F u t u r e studies wilt report detailed comparative analyses between conventional a n d digital i m a g e s in the n e w b o r n c h e s t to m o r e specifically e v a l u a t e the p o t e n t i a l o f digital i m a g i n g for d e t e c t i o n o f b o t h n o r m a l a n d p a t h o l o g i c a l tissues. W e also p l a n to e v a l u a t e t h e a c c u r a c y o f d i a g n o s i s o f f the r e m o t e m o n i t o r s l o c a t e d in the n e w b o r n i n t e n s i v e c a r e a r e a , w h e n c o m p a r e d to d i a g n o s i s m a d e off the h a r d c o p y film. REFERENCES
Alotis, MA (1984). Digital radiographic studies of the esophagus and upper GI tract. RNM Images May/Jun, 32 34. Barnes, GT, Scones, RA & Tesic, MM (1985). Digital chest radiography: Performance evaluation of a prototype unit. Radiology, 154, 801-806. Doi, K, Fujita, H, Ohara, K, Ono, K, Matsui, H, Giger, ML et al. (1986). Digital radiographic imaging system with multiple-slit scanning x-ray beam: Preliminary report. Radiology, 161, 513 518. Fajardo, LL, Hillman, BJ, Hunter, TB, Claypool, HR. Westerman, BR & Mockbee, B (1987). Excretory urography using computed radiography. Radiology, 162, 345 351.
Fraser, RG, Breatnach, E & Barnes, GT (1983). Digital radiography of the chest: Clinical experience with a prototype unit. Radiology, 148, 15. Goodman, LR, Foley, WD, Wilson, CR, Rimm, AA & Lawson, TL (1986). Digital and conventional chest images: observer performance with film digital radiography system. Radiology, 158, 27-33. Kastan, DJ, Ackerman, LV, Feczko, PJ & Beute, GH (1985). Digital radiography: A review. Henry Ford Hospital Medical Journal, 33, 88-94. Kogutt, MS (1987). Computed radiographic imaging: Use in low dose leg length radiography. American Journal of Roentgenology, 148, 1205 1206. Kushner, DC, Cleveland, RH, Herman, TE, Zaleske, D J, Ehrlich, MG & Correia, JA (1986). Radiation dose reduction in the evaluation of scoliosis: An application of digital radiography. Radiology, 161, 174-181. Lares, PM & Cocklin, ML (1986). Spatial resolution requirements for digital chest radiographs: An ROC study of observer performance in selected cases. Radiology, 158, 11 19. MacMahon, H, Vyborny, C J, Metz, CE, Doi, K, Sabeni, V & Solomon, SL (1986). Digital radiography of subtle pulmonary abnormalities: An ROC study of the effect of pixel size on observer performance. Radiology, 158, 21 26. Merritt, CRB (1985). Computed radiography: A new approach to plain film imaging. Diagnostic Imaging, 7, 58 65. Merritt, CRB, Matthews, CC, Tutton, RH, Miller, KD, Belt, KA, Kogutt, MS et al. (1985). Clinical application of digital radiography: Computed radiographic imaging. RadioGraphics, 5, 397-414. Nakano, Y, Togashi, K, Nishimura, K, Itoh, K, Fujisawa, I, Asato, T et al. (1986). Stomach and duodenum: Radiographic magnification using computed radiography (CR). Radiology, 160, 383-387. Nakano, Y, Hiraoka, T, Togoshi, K, Nishimura, K, Itoh, K, Fujisawa, I et aL (1987). Direct radiographic magnification with computed radiography. American Journal of Roentgenology, 148, 569 573. Sartoris, DJ & Sommer, FG (1984). Digital film processing: Applications to the musculoskeletal system. Skeletal Radiology, 11, 274 281. Sashin, D & Sterngtass, EJ (1983). Approaching radiology's theoretical limits. Diagnostic Imaging, 5, 126-131. Smathers, RL & Brody, WR (1985). Digital radiography: Current and future trends. British Journal of Radiology, 58, 285-307. Wilson, AJ & Ramsby, GR (1987). Skeletal measurements using a flying spot digital imaging device. American Journal of Roentgenology, 149, 339-343.
Book Review Radiology- Practical Guides for General Practice 3. By R. F. Bury.
Oxford University Press, Oxford, 1988.96 pp., £4.50. This short book is one in a series providing practical guides on important topics for general practitioners. The aim of this volume is to enable the GP to choose the right examination, prepare the patient, and make sense of the result, also to explain the role of new techniques which will not be available on open access to GPs. The book js divided into four sections. The first section deals with the relationship between the radiologist and GP and contains much common-sense, but advice on how one should 'correct any bad referral habits' is not given. The second section deals with the hazards of diagnostic imaging and these are clearly presented. The 28 day rule is explained: an example of a pregnancy disclaimer form is included. Many women will realise that they cannot be absolutely sure they are not pregnant and the procedure to be followed in this case is not clarified. The third section is an account of imaging in the 80s, describing plain film radiography, fluoroscopy, DVI, CT, US, nuclear medicine and MRI. The descriptions are simple and clear, an outline of the applications of CT and US is given. CT is suggested for obscure abdominal masses not resolved by other means; many radiologists
would argue it should be the first investigation not the last. There are pictures of radiographic equipment in use which are helpful apart from the picture of the CT scanner, which is not very clear. A solitary MRI image is reproduced which does nothing to demonstrate what is possible with this technique. The remainder, and major part, of the book is devoted to a system by system account of investigations, giving indications, patient preparation and a description of the procedure, and some advice on interpreting the result. The advice is dogmatic and sound. The merits of the barium meal versus endoscopy and the oral cholecystogram versus ultrasound are briefly discussed. Sialography and cerebral angiography merit brief descriptions but peripheral angiography does not. Many radiologists will not share the author's enthusiasm for an open access barium enema service. Overall this book achieves its aims very well and covers much ground very concisely and clearly. It deserves to be widely read and should be strongly recommended to any GP seeking to make the best use of the radiology department. For radiologists it provides all the material necessary to prepare the lectures for GPs that the author suggests radiologists should give at their postgraduate centre. E. Barton