Book reviewMedical imaging systemsA. MaccovskiPrentice-Hall, 1983, 256 pp., £26.95ISSN: 13-572685-9

Like many good books on imaging, this particular text isbased on notes prepared for a graduate course in electricalengineering. After an introductory chapter on the historyof medical imaging and a brief survey of the imagingmodalities available, the first chapter of substance is theChapter on the mathematics of linear imaging systems.This includes Sections on the superposition integral as thefundamental concept in linear imaging theory, its simplifi-cation to the convolution integral and the use of the theoryof the Fourier transform in imaging theory. On the whole,the treatment is clear and detailed enough for the averageengineer and physicist involved in medical imaging, andgives a perfectly adequate coverage. It would be far toodetailed for the clinical medical imaging specialist. TheSection on probability in this Chapter is very brief, and,unlike the preceding Sections with which the averagescientific reader may not be familiar, covers very basicground. Presumably this Section was put in for complete-ness, but fails to cover some important topics, such ascovariance.

The succeeding Chapters deal, in turn, with the variousimaging modalities. The detail in these chapters presum-ably represents the author's own preferences and experi-ence which tends to lead to some imbalance. Projectionradiology has four chapters assigned to it, whereas X-raytomography has only one. This may reflect the relativeimportance of these two techniques, in terms of thenumber of investigations performed, but is unlikely toreflect the degree of interest in these different modalitiesamong the scientific readers. The treatment of nuclearmedicine is by comparison rather sketchy. No overall dis-cussion is presented for the total resolution of the system,including both the collimator and intrinsic contributionsto resolution. No discussion is given of the intrinsic non-uniformities of such a system, such as positional nonlin-earities and sensitivity variations; although these would fitquite comfortably into the mathematical framework of thisbook and form an important topic in the theory of radio-isotope imaging devices. Radioisotope tomography israther erratically treated. For example, more mathematicalspace is given to coded aperture systems, which are stilllargely experimental, than to rotational tomography.While it is clearly not the author's intention to describe, indetail, reconstruction algorithms, it would have been useful

to discuss, in more detail, the particular problems associ-ated with reconstruction of such images. A primaryproblem is, of course, the fact that the emitted radiation isattenuated by the body being imaged, but exact solutionsexist for this problem; provided attenuation is uniform anda description of these would have fitted neatly into thisbook. A second problem less easily dealt with is the varia-tion of resolution with depth. In addition, a discussion ofthe effect of detector nonuniformities on this type ofimaging would have been in place. A more detaileddescription of positron imaging would also have beenuseful. The fact that positron imaging offers a relativelysimple solution to the attenuation problem is completelyignored.

The two Chapters on ultrasonic imaging seem fairlydetailed. However, the author quotes with barely any dis-cussion or derivation the basic A-scan equation, giving thereturning echo amplitude as a function of time. Consider-ing the importance of this equation in the rest of theChapter, it is a pity that a few more paragraphs are notspent on it. However, the general treatment after this pointseems fairly complete. The Chapter on ultrasonic arrays isuseful and well constructed.

Finally, a series of other topics are dealt with in a singlechapter; regrettably, one of these is nuclear magnetic res-onance, and, given that this is rapidly becoming an impor-tant technique, it is a pity that the treatment is so brief.Nevertheless, within these limits, the treatment of thephysics is good. The remaining topics covered briefly inthis Section are digital subtraction radiography, energy sel-ective imaging, ultrasonic transmission tomography,Compton scattering imaging and stimulated positron emis-sion imaging.

On the whole, this is a useful book. It would have beennice to have had a few more images included. The radio-isotope images were hardly the state of the art, and did notdo justice to this technique. There is a sense that it hasfailed to quite meet its supposed objectives, of providing afull mathematical treatment of medical imaging tech-niques, which is a pity, because, with some expansion, itcould have drawn together a fairly complete description ofthe mathematics of medical imaging systems. It is to behoped that it will eventually be revised and expanded, totreat more fully some of the imaging methods other thanradiography and ultrasound.

D.C. BARBER

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112 IEE PROCEEDINGS, Vol. 132, Pt. A, No. 2, MARCH 1985