Radioimaging using low dose isotope

A method of functional imaging, comprising:

• (a) administering a radiopharmaceutical selected from the group consisting of Tc-99m-sestamibi, Tc 99m Tetrofosmin and Tl-201-thallous chloride to a patient;
• (b) imaging said patient using one or both of a low dose protocol in which dosage of said radiopharmaceutical is lower by at least a factor of 3 from standard dosage of said radiopharmaceutical set forth in Table 5A and a fast protocol in which substantial acquisition time is shorter than 10 minutes,
• wherein imaging is performed with a radiation camera comprising at least one collimator defining an angle from which the radiation camera detects radiation events and wherein the camera is configured to detect at least one out of 1500 photons emitted from the isotope in an imaged area.