Table B.25: Red bone marrow in the whole body - Helmholtz ...

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3 2. Exposure conditions considered ___________________________________________________________ 2.1. Type of CT scanners and scan geometries A field study conducted by the GSF /6,7/ showed that all CT scanners operated in Germany are rotate-only systems. The distance of the focus to the axis of rotation is usually either 70 cm or 76 cm. Comparisons showed that the organ doses do not differ significantly for these two distances. Therefore, the calculations were performed for a focus-to-axis distance of 75 cm; they are equally applicable for all distances between 70 cm and 85 cm. The angle of rotation is mostly 360°; an angle of 180° is also often used. In the case of the smaller angle, the beam usually impinges at the front side of the body. For the calculations performed for this catalogue, both angles, 360° and 180°, were considered, and organ dose conversion factors are presented for both situations. For 180° rotation, anterior radiation incidence was modelled. For posterior incidence, the appropriate organ dose conversion factors can be obtained from those given (as it will be discussed in section 5.2.1.). In Germany, the use of beam shaping devices between focus and patient is rare; therefore, use of such devices was not modelled. Scans are, however, often performed using an asymmetrical beam, that means the beam is 25 cm wide on one side of the central axis and only 10 cm on the other side. Consequently, only a circle of radius 10 cm around the axis of rotation is symmetrically irradiated, the area outside is not. Due to their small body size, babies are lying entirely within the fully irradiated part of the beam; therefore, asymmetrical beams need not be considered for patients at this age. Older children are broad enough that part of their body is not symmetrically irradiated. This leads to markedly lower doses outside the 10 cm field. For the respective tissues, additional tables for scans using asymmetrical beams are also given.
4 2.2. Radiation qualities Two radiation qualities were considered covering a wide energy range and allowing inter- or extrapolation for beam qualities deviating from those given. The respective spectra are characterised in table 1. In the above mentioned field study, no radiation qualities were found with tube voltages below 80 kV; some scanners were operated at tube voltages above 125 kV, the maximum value being at 137 kV. Previously published data /4/ showed that the organ dose conversion factors for 137 kV tube voltage are similar to those for 125 kV due to the close resemblance of the respective spectra and could, therefore, easily be estimated from those given for 80 kV and 125 kV by linear extrapolation based on mean photon energy (E photon ) or half value layer (HVL) in aluminium. Table 1: Radiation qualities considered Tube voltage Filtration E photon HVL (kV) (mm) (keV) (mm Al) 80 2.2 Al + 0.20 Cu 50.5 5.38 125 2.2 Al + 0.20 Cu 64.4 7.94
Page 1 and 2: Tomographic Anthropomorphic Models
Page 3 and 4: Contents (continued) Appendix B: Or
Page 5 and 6: Contents (continued) Appendix D: Or
Page 7: 2 1. Introduction _________________
Page 11 and 12: 6 all doses presented in this catal
Page 13 and 14: 8 4. Description of the data presen
Page 15 and 16: 10 The last column in each table pr
Page 17 and 18: 12 For reliable determination of or
Page 19 and 20: 14 ever, often performed using an a
Page 21 and 22: 16 during an individual examination
Page 23 and 24: 18 6. Conclusions _________________
Page 25 and 26: 20 References _____________________
Page 28 and 29: 23 Appendix A Anatomical Data of th
Page 30 and 31: 25 Appendix B Organ Dose Conversion
Page 32 and 33: 27 Table B. 1: Adrenals (continued)
Page 34 and 35: 29 Table B. 2: Bladder (continued)
Page 36 and 37: 31 Table B. 4: Breast Mean organ do
Page 38 and 39: 33 Table B. 5: Colon Mean organ dos
Page 40 and 41: 35 Table B. 6: Eye lenses Mean orga
Page 42 and 43: 37 Table B. 7: Kidneys Mean organ d
Page 44 and 45: 39 Table B. 8: Liver Mean organ dos
Page 46 and 47: 41 Table B. 9: Lungs Mean organ dos
Page 48 and 49: 43 Table B.10: Oesophagus Mean orga
Page 50 and 51: 45 Table B.11: Ovaries Mean organ d
Page 52 and 53: 47 Table B.12: Pancreas (continued)
Page 54 and 55: Table B.13: Red bone marrow in the
Page 56 and 57: 51 Table B.14: Red bone marrow in t
Page 58 and 59:
53 Table B.16: Red bone marrow in t
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Page 64 and 65:
Page 66 and 67:
Page 68 and 69:
Page 70 and 71:
Page 72 and 73:
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Page 76 and 77:
Table B.26: Skeleton (whole body) 7
Page 78 and 79:
73 Table B.27: Skin (whole body) Me
Page 80 and 81:
75 Table B.28: Small intestine Mean
Page 82 and 83:
77 Table B.29: Spleen Mean organ do
Page 84 and 85:
79 Table B.30: Stomach Mean organ d
Page 86 and 87:
81 Table B.31: Testes Mean organ do
Page 88 and 89:
83 Table B.32: Thymus (continued) S
Page 90 and 91:
85 Table B.33: Thyroid (continued)
Page 92 and 93:
87 Table B.34: Tissue (whole body)
Page 94 and 95:
89 Appendix C Anatomical Data of th
Page 96 and 97:
91 Appendix D Organ Dose Conversion
Page 98 and 99:
93 Table D. 1: Adrenals (continued)
Page 100 and 101:
95 Table D. 2: Bladder (continued)
Page 102 and 103:
97 Table D. 3: Brain (continued) Sl
Page 104 and 105:
99 Table D. 4: Breast (continued) S
Page 106 and 107:
101 Table D. 5: Colon (ascending an
Page 108 and 109:
103 Table D. 6: Colon (descending a
Page 110 and 111:
Table D. 7: Eye lenses (continued)
Page 112 and 113:
107 Table D. 8: Kidneys (continued)
Page 114 and 115:
109 Table D. 9: Liver (continued) S
Page 116 and 117:
111 Table D.10: Lungs (continued) S
Page 118 and 119:
113 Table D.11: Oesophagus (continu
Page 120 and 121:
115 Table D.12: Ovaries (continued)
Page 122 and 123:
Table D.13: Pancreas (continued) 11
Page 124 and 125:
119 Table D.14: Red bone marrow in
Page 126 and 127:
Page 128 and 129:
Page 130 and 131:
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Page 134 and 135:
Page 136 and 137:
Page 138 and 139:
Page 140 and 141:
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Page 144 and 145:
Page 146 and 147:
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Page 150 and 151:
Table D.28: Skeleton (whole body) 1
Page 152 and 153:
147 Table D.29: Skin (whole body) M
Page 154 and 155:
149 Table D.30: Small intestine Mea
Page 156 and 157:
151 Table D.31: Spleen Mean organ d
Page 158 and 159:
153 Table D.32: Stomach Mean organ
Page 160 and 161:
155 Table D.33: Testes Mean organ d
Page 162 and 163:
157 Table D.34: Thymus Mean organ d
Page 164 and 165:
159 Table D.35: Thyroid Mean organ
Page 166 and 167:
161 Table D.36: Tissue (whole body)
Page 168 and 169:
163 Table D.37: Uterus Mean organ d
Page 170 and 171:
165 Appendix E Selected Organ Dose
Page 172 and 173:
167 Table E. 1: Red bone marrow in
Page 174 and 175:
Page 176 and 177:
Page 178 and 179:
Page 180 and 181:
175 Table E. 5: Skeleton (whole bod
Page 182 and 183:
177 Table E. 6: Skin (whole body) (
Page 184:
179 Table E. 7: Tissue (whole body)
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Table B.25: Red bone marrow in the whole body - Helmholtz ...

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