Resonant gamma absorption is proposed for in-vivo detection and imaging of body nitrogen and calcium. Two major applications are nutritional assessment of critically ill patients and osteoporosis screening. Required radiation doses for whole-body measurements are 3-4 orders of magnitude lower than may be done by present techniques. A novel, compact electrostatic proton accelerator is proposed to produce a 1 mA proton beam of energy 1.75 MeV (for nitrogen detection) or 2.04 MeV (for Ca detection). Protons captured in a target produce gamma rays resonant with either N or Ca. The measured transmission of the resonant gammas through the body is used to determine the body content of these elements. The technique requires no radioactive source and a dose so modest that body scans with 2 cm resolution are envisioned. Phase I is a theoretical effort to quantify the technique, design an electrostatic accelerator, and optimize the geometric interfacing between the accelerator, target and detector system.
