Book excerpt: This book serves as a practical guide to solving problems presented in THE PHYSICS OF RADIOLOGY, Fourth Edition. The authors contend that one does not really understand physics unless one can use it to solve problems and they have encouraged classroom problem-solving and discussion of solutions. This volume enhances that process. Approximately half of the problems found at the end of each chapter in the text have been selected with reasonable solutions provided. Solutions include, where appropriate, discussion of assumptions that may have to be made, and where the relevant formulae and data are to be found. Explanations of the reasoning used in arriving at the solutions are given as are comments that are intended to show the important aspects of each problem.