00,000 to 700,000 with the suggested number being approximately 350,000. depending on the activity added and volume of the final reconstituted product, the volume of the dose may vary from 0.2 to 1.9 ml. the number of particles available per dose of technetium tc 99m albumin aggregated injection will vary depending on the physical decay of the technetium tc-99m that has occurred. the number of particles in any dose and volume to be administered may be calculated as follows: where: v tc = volume of solution added to reaction vial d = desired dose to be administered in mbq (mci) c = concentration at calibration time of sodium pertechnetate solution to be added to the reaction vial in mbq/ml (mci/ml) v a = volume to be administered in ml p = number of particles in dose to be administered f r = fraction of technetium tc-99m remaining after the time of calibration (see table 3) n = number of particles per vial. the number of particles per vial for each lot is shipped with the product. in pediatric patients, the suggested intravenous dose to be employed for perfusion lung imaging is in the range of 0.925 to 1.85 mbq per kilogram (25 to 50 μci/kg) of body weight; a usual dose is 1.11 mbq per kilogram (30 μci/kg), except in newborns, in whom the administered dose should be 7.4 to 18.5 mbq (200 to 500 μci). not less than the minimum dose of 7.4 mbq (200 μci) should be employed for this procedure. the number of particles will vary with age and weight of the pediatric patient as indicated in table 5. parenteral drug products should be visually inspected for particulate matter and discoloration prior to administration whenever solution and container permit. the patient dose should be measured by a suitable radioactivity calibration system immediately prior to administration. mix the contents of the vial by gentle inversion just prior to withdrawing a patient dose. mix the contents of the syringe just before injection. if blood is drawn into the syringe, any unnecessary delay prior to injection may lead to clot formation. for optimum results and because of rapid lung clearance of the radiopharmaceutical, it is suggested that the patient be positioned under the imaging apparatus before administration. slow injection is recommended. lung imaging may begin immediately after intravenous injection of the radiopharmaceutical. due to high kidney uptake, imaging later than one-half hour after administration will yield poor results. radiation dosimetry the estimated absorbed radiation doses 1 to an average adult patient (70 kg) from an intravenous injection of 148 mbq (4 mci) of technetium tc 99m albumin aggregated injection are shown in table 4. table 4 - absorbed radiation doses organs mgy/148 mbq rad/4 mci total body lungs liver spleen kidneys bladder wall 2 hr. void 4.8 hr. void testes 2 hr. void 4.8 hr. void ovaries 2 hr. void 4.8 hr. void 0.6 8.8 0.72 0.68 0.44 1.2 2.2 0.24 0.26 0.3 0.34 0.06 0.88 0.072 0.068 0.044 0.12 0.22 0.024 0.026 0.03 0.034 1 method of calculation: “s” absorbed dose per unit cumulated activity for selected radionuclides and organs, mird pamphlet no. 11 (1975). in pediatric patients, the radiation absorbed doses using the maximum recommended dose for lung imaging are based on 1.85 mbq (50 μci) per kilogram of body weight [except in the newborn where the maximum recommended dose of 18.5 mbq (500 μci) is used] and are shown in table 5, which lists the maximum dose for pediatric patients from newborn to adults. note the recommendations regarding number of particles to be administered. table 6 represents the absorbed radiation dose resulting from the intraperitoneal administration of 111 megabecquerels (3 millicuries) of technetium tc 99m albumin aggregated. table 5 - pediatric radiation dose from tc 99m maa for lung imaging* (1) 2 hour voiding interval (2) 4.8 hour voiding interval age newborn 1 year 5 years 10 years 15 years weight (kg) 3.5 12.1 20.3 33.5 55 max. recommended dose in megabecquerels and millicuries mbq 18.5 mci 0.5 mbq 22.2 mci 0.6 mbq 37 mci 1 mbq 62.9 mci 1.7 mbq 103.6 mci 2.8 range of particles administered 10,000 to 50,000 50,000 to 150,000 200,000 to 300,000 200,000 to 300,000 200,000 to 700,000 absorbed radiation dose in milligray and rad for the maximum dose mgy rad mgy rad mgy rad mgy rad mgy rad organs total body lungs liver bladder wall ovaries testes 0.6 19 1.4 2.1 0.38 0.31 0.06 1.9 0.14 0.21 (1) 0.038 0.031 0.3 6.6 0.6 1.5 0.2 0.13 0.03 0.66 0.06 0.15 (1) 0.02 0.013 0.31 5.8 0.62 3.1 0.19 0.19 0.031 0.58 0.062 0.31 (2) 0.019 0.019 0.48 8.7 1.8 3.9 0.44 0.2 0.048 0.87 0.18 0.39 (2) 0.044 0.02 0.41 7.7 1.2 4.1 0.41 0.36 0.041 0.77 0.12 0.41 0.041 0.036 *assumptions: 1. used biologic data from kaul et al ., berlin, 1973. 2. for the newborn, 1-year old, and 5-year old, the “s” values calculated from the preliminary phantoms of ornl were used. the 10-year old, 15-year old and adult “s” values were taken from henrichs et al. , berlin, 1980. table 6 - absorbed radiation doses* organs shunt patency (open) shunt patency (closed) mgy rad mgy rad lung ovaries & testes organs in the peritoneal cavity total body 6.9 0.18 to 0.3 - 0.36 0.69 0.018 to 0.03 - 0.036 1.68 1.68 1.68 0.57 0.168 0.168 0.168 0.057 *assumptions: calculations for the absorbed radiation dose are based upon an effective half-time of 3 hours for the open shunt and 6.02 hours for the closed shunt and an even distribution of the radiopharmaceutical in the peritoneal cavity with no biological clearance. choose image

fragile for the capillary micro-occlusion to be temporary. erosion and fragmentation reduce the particle size, allowing passage of the aggregates through the pulmonary alveolar capillary bed. the fragments are then accumulated by the reticuloendothelial system. lung to liver ratios greater than 20:1 are obtained in the first few minutes post-injection. elimination of the technetium tc 99m aggregated albumin from the lungs occurs with a half-life of about 2 to 3 hours. cumulative urinary excretion studies show an average of 20% elimination of the injected technetium tc 99m dose 24 hours post-administration. following administration of technetium tc 99m albumin aggregated by intraperitoneal injection, the radiopharmaceutical mixes with the peritoneal fluid. clearance from the peritoneal cavity varies from insignificant, which may occur with complete shunt blockage, to very rapid clearance with subsequent transfer into the systemic circulation when the shunt is patent. serial images should be obtained of both the shunt and lung (target organ). however, an adequate evaluation of the difference between total blockage of the shunt and partial blockage may not be feasible in all cases.