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

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11 5. Derivation of organ doses for individual examinations ___________________________________________________________ 5.1. Instructions for the use of the organ dose conversion factors The dose values of this catalogue are presented as organ dose conversion factors, i.e. organ absorbed doses normalised to the air kerma free in air at the axis of rotation. Mean organ doses for individual examinations can be calculated according to the formula zu D( organ) = K f ( organ, z) air •∑ z by summing up the values of f(organ,z) as listed in the tables of Appendix B, D or E and multiplying the resulting sum with K air , the air kerma free in air on the axis of rotation. z l and z u indicate the lower and upper boundaries of the scanned region. For easier orientation, approximate positions of anatomical landmarks are indicated in Appendices A and C. Examinations can be treated in one step using the above equation as long as the dose on the axis remains constant. Sections in which K air is changed are to be treated separately and the sum of the resulting values of D(organ) gives the total value for the whole examination. This procedure is independent of the actual slice width used. Calculations performed in order to study the effect of slice width on the organ dose conversion factors revealed no significant differences between the doses resulting from one single slice of 1 cm width and those resulting from summation of five contiguous slices of 2 mm width /4/. l
12 For reliable determination of organ doses, K air should be based on measurements at the respective unit using suitable dosimeters and considering the influence of geometric effects like overlapping of adjacent slices or spaces between them. The CT Dose Index (CTDI) is the most suitable quantity in this context. It should be noted, however, that the organ dose conversion factors of this report refer to the CTDI measured free in air and not in a phantom. If dose measurements are not possible or if only rough estimates of organ doses are intended, values from literature can be used for K air . Also in these cases, the use of CTDI values measured free in air has to be ensured. Table 3 presents literature values of K air for some spectra likely to be used in CT examinations /12,13/. These values should be used with caution, however, as a field study covering 120 CT units in Germany revealed that actual dose measurements may differ markedly from the literature values even for the same nominal conditions /6,7/. Therefore, actual measurements of K air should be preferred whenever possible. Table 3: Literature values for dose free in air at 75 cm distance, normalised to 100 mAs /12,13/. Tube voltage Filtration K air Reference (kV) (mm) (mGy) 80 2.2 Al + 0.20 Cu 4.4 /12/ 125 2.2 Al + 0.20 Cu 14.4 /12/ 125 2.0 Al + 0.25 Cu 13.2 /12/ 137 2.2 Al + 0.20 Cu 17.6 /12/ 125 2.0 Al + 0.40 Cu 9.6 /12/ 125 2.5 Al + 0.40 Cu 11.0 /13/ 120 5.0 Al + 0.50 Cu 6.7 /13/ 5.2. Situations different from those considered in the calculation Strictly speaking, the organ dose conversion factors presented in this catalogue are valid only for the same exposure conditions for which they
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 and 8: 2 1. Introduction _________________
Page 9 and 10: 4 2.2. Radiation qualities Two radi
Page 11 and 12: 6 all doses presented in this catal
Page 13 and 14: 8 4. Description of the data presen
Page 15: 10 The last column in each table pr
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
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61 Table B.20: Red bone marrow in t
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Table B.26: Skeleton (whole body) 7
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73 Table B.27: Skin (whole body) Me
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75 Table B.28: Small intestine Mean
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77 Table B.29: Spleen Mean organ do
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79 Table B.30: Stomach Mean organ d
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81 Table B.31: Testes Mean organ do
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83 Table B.32: Thymus (continued) S
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85 Table B.33: Thyroid (continued)
Page 92 and 93:
87 Table B.34: Tissue (whole body)
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89 Appendix C Anatomical Data of th
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91 Appendix D Organ Dose Conversion
Page 98 and 99:
93 Table D. 1: Adrenals (continued)
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95 Table D. 2: Bladder (continued)
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97 Table D. 3: Brain (continued) Sl
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99 Table D. 4: Breast (continued) S
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101 Table D. 5: Colon (ascending an
Page 108 and 109:
103 Table D. 6: Colon (descending a
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Table D. 7: Eye lenses (continued)
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107 Table D. 8: Kidneys (continued)
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109 Table D. 9: Liver (continued) S
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111 Table D.10: Lungs (continued) S
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113 Table D.11: Oesophagus (continu
Page 120 and 121:
115 Table D.12: Ovaries (continued)
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Table D.13: Pancreas (continued) 11
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119 Table D.14: Red bone marrow in
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Table D.28: Skeleton (whole body) 1
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147 Table D.29: Skin (whole body) M
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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
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165 Appendix E Selected Organ Dose
Page 172 and 173:
167 Table E. 1: Red bone marrow in
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175 Table E. 5: Skeleton (whole bod
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177 Table E. 6: Skin (whole body) (
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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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