ABSTRACT
Nuclear medicine imaging techniques traditionally involve the use of tracer amount of pharmaceuticals labeled with radionuclides or radiopharmaceuticals. By tracking the radiation, usually gamma-ray photons, emitting from distribution of the radiopharmaceutical among different tissues or organs within the human body, information about the functions of the tissues or organs can be obtained through the differential uptakes of the radiopharmaceuticals. Traditional single-photon emission computed tomography (SPECT) for clinical applications is based on one or more standard scintillation camera mounted on a rotational gantry that places the camera at positions around the patient to acquire 2D projection images at different views. Pinhole collimator is a simple design that has been used in clinical nuclear medicine and SPECT imaging of small organs such as the thyroid. By placing a small object close to the pinhole aperture, substantial increase in photon detection efficiency as compared with parallel-hole collimation can be achieved through magnification of the object onto the detector plan.
