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Book review |
This is the 8th edition of a book on practical radiography that was first published in 1955. Since the book has stood the test of time, it can be expected to contain much good material, and indeed it does; e.g. the book is clearly focused on radiographers and covers everything one needs to know about the practical aspects of planar imaging.
I also like the way in which the book is structured. It starts from the premise that there are only six essential imaging qualities — density, contrast, noise, sharpness, magnification and distortion – and in each chapter the effect of a radiographic variable (e.g. tube potential, focal spot, grids) on each imaging quality is analysed. This keeps the mind focused on the role of the radiographer in producing good quality images. Towards this end, I particularly liked the numerous figures showing the effects of less-than-optimum settings on image quality (e.g. 10 repeat radiographs of the chest — 5 showing high contrast at 50 kVp but low exposure latitude; 5 showing lower contrast at 80 kVp but more exposure latitude). Such images are invaluable for teaching but should they, or could they, be taken under current UK Medical Exposure Regulations? Although much of the good practice emphasised in the book is directed towards image quality and patient dose reduction, only one chapter of six pages is devoted specifically to the latter topic.
The advice on how image quality can be optimized is accurate, but also rather empirical; e.g. how can one understand the subtleties of changes in optical density on film without being aware of the highly non-linear relationship between optical density and exposure? However, the Hurter and Driffield characteristic curve is not mentioned until pp. 604. In those places where explanation of the physical principles is attempted in further depth, there are many errors. I was disappointed that the book had reached the 8th edition without the following statement being corrected (pp. 11): "In tungsten atoms, characteristic X-rays will be produced in the innermost electron shell having 57, 66 and 69 kilovolts of energy. The second orbital shell will produce X-rays of 10 and 12 keV, and the third shell will produce X-rays with about 2 keV. Inherent beam filtration will remove virtually all the 2 kV X-rays". Is it any wonder that many student radiographers do not understand the difference between kV and keV?
The accompanying Instructor's Manual consists mainly of 645 multiple choice questions based on the various chapters, together with answers. As with the main text, the emphasis is on simple factual or numerical recall, with little depth of understanding; e.g. Chapter 1, Q3 "What is the intensity of the remnant beam striking the film as a percentage of the original beam entering the patient?" The "correct" answer is given as 30% (as on pp. 13 of the main text) but this varies enormously with the thickness of the body part being radiographed, the kVp of the radiation and the field size. The two smaller sections comprise calculations (e.g. mAs when mA and time of exposure are known, and inverse square law) and laboratory exercises. Although fairly basic, they are essential learning for a radiographer.
At $69.95 the book and manual are reasonably priced. They would be a useful acquisition for a library where radiographers and others could revise aspects of the imaging processes. The book would also be useful to a good teacher who could provide the explanations that are missing. Because of its empirical nature, I would not recommend it to a student who does not have that broad overview at an early stage in their training.
A further consideration is that this edition may be overtaken by the rapid growth of digital radiography. Although four new chapters on digital imaging have been added, the book is heavily orientated towards film. As digital images become more prevalent, it will become apparent that many statements in the book on analogue film images (e.g. those relating to grey scale) do not apply universally, or must be interpreted in a different way, for digital images.
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