RADIATION PROTECTION - ILEA

Contents
xv
16 Exposure from Internal Radiation Sources 77
16.1 The Activity—A Quantity for Describing the Amount
of Radioactivity 77
16.2 The Unit of Activity—The Becquerel 77
16.3 The Accumulating Dose from Radioactivity in the Body
and the Committed Dose 78
17 The Annual Limit on Intake—The Basic Quantity for the Control
of Internal Exposures 80
18 Limit for the Concentration of a Radionuclide in Air—
A Derived Limit 81
19 Levels of Radioactivity inside the Body—A Useful Benchmark
for Internal Exposure 82
20 Protection from Radioactive Contamination 84
21 Some Simple Calculations in Radiation Protection 85
21.1 Dose from Beta Particles 85
21.2 Exposure Rate and Dose Rate from Gamma Photons 89
21.3 Reduction of Dose Rate by Both Distance and Shielding 91
21.4 Correction for Radioactive Decay 92
21.5 Shielding of Large or Complex Sources 92
22 X Rays—Radiation Made by Machine 94
22.1 Production of X Rays 96
22.2 Diagnostic Radiology 98
22.3 X-Ray Attenuation in the Body 99
22.4 Effects of Photon Energy Distribution on Image Formation and
Absorbed Dose 101
22.5 A Description of an X-Ray Machine 105
22.6 Production of a Photograph of the X-Ray Image 111
22.7 Fluoroscopy 112
22.8 Mammography 116
22.9 Computed Tomography: Taking Cross Sections with X Rays 119
22.10 Technical Approaches for Minimizing the Doses Required to
Record an X Ray 121
22.11 Impact of the Digital Computer in Radiation Medicine 123
23 Dose Measurements in Diagnostic Radiology 124
24 Exposure Guides and Reference Levels in Diagnostic Radiology 127
25 Protection of the Patient in X-Ray Diagnosis 129
25.1 Principles 131
25.2 Policy of the International Commission on Radiological Protection 132
25.3 Studies in the United Kingdom 133