Table 2. Dose–length product (DLP) to effective dose (E) conversion coefficients.
| Examination | Age groupa |
E/DLP conversion coefficient (mSv mGy−1 cm−1)b |
|||
| ICRP 60 [9] | ICRP 103 [26]c | ICRP 103 [33]d | ICRP 103 [34]d | ||
| CT brain | 0–6 months [0 years] | 0.0110 | 0.0076 | 0.0085 | 0.0130 |
| 6 months to 3 years [1 year] | 0.0067 | 0.0046 | 0.0053 | 0.0080 | |
| 3–6 years [5 years] | 0.0040 | 0.0028 | 0.0035 | 0.0050 | |
| 6–10 years [10 years] | 0.0032 | 0.0022 | 0.0027 | 0.0040 | |
| >10 years [adult] | 0.0021 | 0.0014 | 0.0019 | 0.0020 | |
| CT chest | <5 years [1 year] | 0.0260 | 0.0320 | 0.0260 | 0.0380 |
| 5–10 years [5, 10 years] | 0.0160 | 0.0190 | 0.0140 | 0.0230 | |
| >10 years [10 years] | 0.0130 (0.0140)b | 0.0160 (0.0170)b | 0.0120 (0.0150)b | 0.0190 (0.0200)b | |
| CT abdomen/pelvis | <5 years [1, 5 years] | 0.0250 | 0.0230 | 0.0220 | 0.0260 |
| 5–10 years [5, 10 years] | 0.0180 | 0.0160 | 0.0140 | 0.0180 | |
| >10 years [10 years] | 0.0150 (0.0150)b | 0.0140 (0.0140)b | 0.0120 (0.0140)b | 0.0150 (0.0150)b | |
ICRP, International Commission on Radiological Protection.
aThe age groups used in the survey were based on the categorisations used for CT protocols at Royal Children's Hospital Melbourne, Parkville, Australia. Since conversion coefficients are generally defined for a specific age, these were matched to the age groups used in the survey. The age specific to the conversion coefficients is shown in square brackets in this column. For example, for the 0- to 6-month age group for CT brain examinations in this survey, the age-specific conversion coefficient for 0-year-olds has been used. In some cases, an average of conversion coefficients was used based on the distribution of ages in the survey and, for these, two ages have been listed in the square brackets.
bAll values of the conversion coefficients are relative to the 16-cm dosimetry phantom, except those shown in round brackets, which are relative to the 32-cm dosimetry phantom and are for adults. Some of the patients in the >10 years age group will be closer in size to an adult than to a child.
cThese conversion coefficients were derived from the previous study by Brady et al [26] as described in the Methods and materials section. These values have been used to calculate the ICRP 103 effective doses given in Table 4.
dThe conversion coefficients provided by Deak et al [33] are age specific and tube potential specific. The tube potential for each protocol is given in Table 1. All body conversion coefficients in Deak et al [33] have been provided relative to the 32-cm dosimetry phantom and therefore have been divided by 2 to be expressed relative to the 16-cm dosimetry phantom, except for the values in rounded brackets. Deak et al [33] provided separate conversion coefficients for the abdomen and the pelvis. For the CT abdomen/pelvis examinations the conversion coefficients have been averaged. The conversion coefficients given for the CT abdomen/pelvis examinations for Alessio and Phillips [34] relate to the abdomen only.