A method and apparatus for detecting radiation including x-ray, gamma ray, and particle radiation for nuclear medicine are described. A detection system employs fixed or configurable arrays of one or more detector modules comprising detector arrays that may be electronically manipulated through a computer system. The detection system, by providing the ability for electronic manipulation, permits adaptive imaging. The components of the imaging chain can be calibrated or corrected using processes of the invention. One or more reference sources with know properties (such as shape, composition, radionuclide activity distribution and energies, incorporated magnetic, acoustic inductive, or x-ray attenuating materials) can be inserted into the subject. The position of the reference sources can be monitored. Once the reference sources are near the desired location or locations they can be used to calibrate or tune the detection system. The detection system can be focused. Radiation attenuation information (absorption and scattering) can be measured and used to correct for these attenuation effects in the acquired images of the subject.