Fludeoxyglucose F 18 Injection


Fludeoxyglucose F 18 Injection (fdg) is a positron emitting radiopharmaceutical containing no-carrier added radioactive 2-deoxy-2-[18F]fluoro-D-g1ucose, which is used for diagnostic purposes in conjunction with Positron Emission Tomography (PET). It is administered by intravenous injection.

The active ingredient 2-deoxy-2-[18F]fluoro-D-g1ucose (Fludeoxyglucose F 18), abbreviated [18F] FDG, has a molecular formula of C6H1118FO5 with a molecular weight of 181.26 daltons, and has the following chemical structure:

Fludeoxyglucose F 18 Structural Formula Illustration

Fludeoxyglucose F 18 Injection (fdg) is provided as a ready to use isotonic, sterile, pyrogen free, clear, colorless citrate buffered solution. Each mL contains between 0.37 to 3.7 GBq (10.0 - 100 mCi) of 2-deoxy-2-[18F]fluoro-D glucose at the end of synthesis (EOS), 4.5 mg of sodium chloride and 7.2 mg of citrate ions. The pH of the solution is between 5.0 to 7.5. The solution is packaged in a multiple-dose glass vial and does not contain any preservative.

Physical Characteristics

Fluorine F 18 decays by positron (?+) emission and has a half-life of 109.7 minutes. The principal photons useful for diagnostic imaging are the 511 keV gamma photons, resulting from the interaction of the emitted positron with an electron (Table 1).

Table 1. Principal Emission Data for Fluorine F 18

Radiation/Emission % per Disintegration Mean Energy
Positron (?+) 96.73 249.8 keV
Gamma (?)* 193.46 511.0 keV
*Produced by positron annihilation
From: Kocher, D.C. "Radioactive Decay Tables" DOE/TIC-11026, 89 (1981).

External Radiation

The specific gamma ray constant for fluorine F 18 is 6.0 R/hr/mCi (0.3 Gy/hr/kB) at 1cm. The half-value layer (HVL) for the 511 keV photons is 4.1 mm lead (Pb). A range of values for the attenuation of radiation results from the interposition of various thickness of Pb. The range of attenuation coefficients for this radionuclide is shown in Table 2. For example, the interposition of an 8.3 mm thickness of Pb, with a coefficient of attenuation of 0.25, will decrease the external radiation by 75%.

Table 2. Radiation Attenuation of 511 keV Photons by Lead (Pb) Shielding

Shield Thickness (Pb) mm Coefficient of Attenuation
0 0.00
4.1 0.50
8.3 0.25
13.2 0.10
26.4 0.01
52.8 0.001

For use in correcting for physical decay of this radionuclide, the fractions remaining at selected intervals after calibration are shown in Table 3.

Table 3. Physical Decay Chart for Fluorine F 18

Minutes Fraction Remaining
0* 1.00
15 0.909
30 0.826
60 0.683
110 0.500
220 0.250
440 0.060
* Calibration time

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