This thesis presents detailed calculations of the dosage to the metaphyses of the distal femur and proximal tibia and fibula of two children, ages 4 and 13. Parameters studied for each child include: mass and dimensions of the growth plate area; effective half-life and cumulated activity for 99mTc-EHDP; and mean dose per unit cumulated activity for the disc geometry of the metaphyses. Consideration is given to the use of the gamma camera for conjugate view counting. The effects of source to collimator distance, source length, and absorber thickness on the absolute count rate are evaluated. In addition, S factors for the various radionuclides have been calculated for spheres and ellipsoids of masses down to one gram.