Questions 223Table14.7. Fraction of adult administered dosages for pediatric administration.
Weight in kg (lb) Fraction Weight in kg (lb) Fraction
3 (6.6) 0.10 28 (61.6) 0.58
4 (8.8) 0.14 30 (66.0) 0.62
8 (17.6) 0.23 32 (70.4) 0.65
10 (22.0) 0.27 34 (74.8) 0.68
12 (26.4) 0.32 36 (79.2) 0.71
14 (30.8) 0.36 38 (83.6) 0.73
16 (35.2) 0.40 40 (88.0) 0.76
18 (39.6) 0.44 42 (92.4) 0.78
20 (44.0) 0.46 44 (96.8) 0.80
22 (48.4) 0.50 46 (101.2) 0.83
24 (52.8) 0.53 48 (105.6) 0.85
26 (57.2) 0.56 50 (110.0) 0.88
Adapted from Paediatric Task Group European Association Nuclear Medicine Members. A
radiopharmaceuticals schedule for imaging paediatrics.Eur J Nucl Med.1990;17:127.
surface area, combination of weight and area, and simple ratios of adult
dosages. The calculation based on body surface area is more accurate for
pediatric dosages. The body surface area of a standard adult is 1.73 m^2 and
proportional to the 0.7 power of the body weight. Based on the informa-
tion, the Paediatric Task Group European Association Nuclear Medicine
Members published the fractions of the adult dosages needed for children,
which are shown in Table 14.7. For most nuclear studies, however, there is
a minimum dosage required for a meaningful scan, which is normally estab-
lished in each institution based on experience.
Questions
- Calculate the absorbed dose to the thyroid gland of a hyperthyroid
patient from a dosage of 30 mCi^131 I, assuming 60% uptake, a biologi-
cal half-life of 4 days for thyroid clearance of^131 I, and Sequal to 2.2 ×
10 −^2 rad/mCi·hr. - Calculate the dose in rems and sieverts to a tumor that received 35 rads
(0.35 Gy) from neutron therapy (radiation weighting factor =10 for
neutrons). - What is the difference between the effective dose equivalent and effec-
tive dose? - Identify as true or false if the following affect the absorbed fraction of
a g-emitting radionuclide:
(a) g-ray energy
(b) Shape of the target organ