massachusetts general hospital - Medication Listings

11.1 Chemical Characteristics Ammonia N 13 Injection is a positron emitting radiopharmaceutical that is used for diagnostic purposes in conjunction with positron emission tomography (PET) imaging. The active ingredient, [ 13 N] ammonia, has the molecular formula of 13 NH3 with a molecular weight of 16.02 g and has the following chemical structure: Ammonia N 13 Injection is provided as a ready to use sterile, pyrogen-free, clear and colorless solution. Each mL of the solution contains between 0.138 GBq to 1.387 GBq (3.75 mCi to 37.5mCi) of [ 13 N] ammonia, at the end of synthesis (EOS), in 0.9% aqueous sodium chloride. The pH of the solution is between 4.5 to 7.5. The recommended dose of radioactivity (0.368 GBq-0.736 GBq, (10 mCi-20 mCi) is associated with a theoretical mass dose of 0.5-1.0 picomoles (8.47-16.94 picograms) of ammonia. ammonia-n-13-01 11.2 Physical Characteristics Nitrogen N 13 decays by emitting positron to Carbon C 13 (stable) and has a physical half-life of 9.96 minutes. The principal photons useful for imaging are the dual 511 keV gamma photons that are produced and emitted simultaneously in opposite direction when the positron interacts with an electron (Table 2). *Produced by positron annihilation Table 2: Principal Radiation Emission Data for Nitrogen 13 Radiation/Emission % Per Disintegration Energy Positron(β+) 100 1190 keV (Max.) Gamma(±)* 200 511 keV The specific gamma ray constant (point source air kerma coefficient) for nitrogen N13 is 1.39 x 10 -6 Gy/hr/kBq (5.9 R/hr/mCi) at 1 cm. The half-value layer (HVL) of lead (Pb) for 511 keV photons is 4 mm. Selected coefficients of attenuation are listed in Table 3 as a function of lead shield thickness. For example, the use of 39 mm thickness of lead will attenuate the external radiation by a factor of about 1000. Table 3: Radiation Attenuation of 511 keV Photons by lead (Pb) shielding Shield Thickness (Pb) mm Coefficient of Attenuation 4 0.5 8 0.25 13 0.1 26 0.01 39 0.001 52 0.0001 Table 4 lists fractions remaining at selected time intervals from the calibration time. This information may be used to correct for physical decay of the radionuclide. *Calibration time Table 4: Physical Decay Chart for Nitrogen N 13 Minutes Fraction Remaining 0* 1.000 5 0.706 10 0.499 15 0.352 20 0.249 25 0.176 30 0.124

11.1 Chemical Characteristics Fludeoxyglucose F 18 Injection is a positron emitting radiopharmaceutical that is used for diagnostic purposes in conjunction with positron emission tomography (PET) imaging. The active ingredient 2-deoxy-2-[ 18 F]fluoro-D-glucose has the molecular formula of C 6 H 11 18 FO 5 with a molecular weight of 181.26, and has the following chemical structure: Fludeoxyglucose F 18 Injection is provided as a ready to use sterile, pyrogen free, clear, colorless citrate buffered solution. Each mL contains between 0.74 GBq to 11.1 GBq (20 mCi to 300 mCi) of 2-deoxy-2-[ 18 F]fluoro-D-glucose at the EOS, 4.5 mg of sodium chloride in citrate buffer. . The pH of the solution is between 4.5 and 7.5. The solution is packaged in a multiple-dose glass vial and does not contain any preservative. Chemical Structure 11.2 Physical Characteristics Fluorine F 18 has a physical half-life of 109.7 minutes and decays to Oxygen O 18 (stable) by positron decay. The principal photons useful for imaging are the dual 511 keV "annihilation" gamma photons, that are produced and emitted simultaneously in opposite directions when the positron interacts with an electron (Table 2). Table 2. Principal Radiation Emission Data for Fluorine F 18 Radiation/Emission % Per Disintegration Mean Energy Positron(β+) 96.73 249.8 keV Gamma(±) 193.46 511.0 keV *Produced by positron annihilation. From: Kocher, D.C. Radioactive Decay Tables DOE/TIC-I 1026, 89 (1981) The specific gamma ray constant (point source air kerma coefficient) for fluorine F 18 is 5.7 R/hr/mCi (1.35 × 10 -6 Gy/hr/kBq) at 1 cm. The half-value layer (HVL) for the 511 keV photons is 4 mm lead (Pb). The range of attenuation coefficients for this radionuclide as a function of lead shield thickness is shown in Table 3. For example, the interposition of an 8 mm thickness of Pb, with a coefficient of attenuation of 0.25, will decrease the external radiation by 75%. Table 3. Radiation Attenuation of 511 keV Photons by lead (Pb) shielding Shield thickness (Pb) mm Coefficient of attenuation 0 0.00 4 0.50 8 0.25 13 0.10 26 0.01 39 0.01 52 0.0001 For use in correcting for physical decay of this radionuclide, the fractions remaining at selected intervals after calibration are shown in Table 4. Table 4. Physical Decay Chart for Fluorine F 18 Minutes Fraction Remaining 0 1.000 15 0.909 30 0.826 60 0.683 110 0.500 220 0.250 *calibration time