Cross-calibration for quantitative functional imaging

A method for cross-calibration for quantitative single photon emission computed tomography (SPECT) to reduce inaccuracies from dose and detector sensitivity, the method performed using a gamma camera and a computer system including a processor and memory comprising:

• obtaining by the processor, as loaded from memory or received by transfer, class standard planar sensitivities of a gamma camera class to a first long-lived source and to a first liquid radiotracer source;
• measuring a system specific planar sensitivity of a gamma camera of the gamma camera class to a second long-lived source by the gamma camera and processor;
• receiving a measured dose calibrator referenced liquid radiotracer sensitivity of a second liquid radiotracer by the processor;
• calculating by the processor a system specific planar sensitivity to the second liquid radiotracer as a function of the class standard planar sensitivities of the gamma camera to the first liquid radiotracer source and the first long-lived source and of the system specific planar sensitivity of the gamma camera to the second long-lived source;
• determining a cross-calibration factor as a function of the system specific planar sensitivity to the second liquid radiotracer and of the dose calibrator referenced liquid radiotracer sensitivity of the second liquid radiotracer;
• correcting a dose value by the processor of the second liquid radiotracer with the cross-calibration factor;
• and
• estimating activity concentration in a patient having the second liquid radiotracer, the estimating using the system specific planar sensitivity by the processor as part of reconstructing into object space detected emission from the second liquid radiotracer in the patient to assist in diagnosis and/or therapy for the patient.