The AAPM/RSNA physics tutorial for residents. Physics of SPECT

Area of Science:

• Medical Imaging
• Nuclear Medicine
• Radiophysics

Background:

• Single-photon emission computed tomography (SPECT) is a crucial 3D imaging modality for visualizing radiopharmaceutical distribution in patients.
• SPECT combines scintigraphy and computed tomography, yielding higher contrast and detail than planar scintigrams.
• SPECT systems utilize scintillation cameras to acquire projection data, which are then reconstructed into 3D images.

Purpose of the Study:

• To elucidate the principles and applications of SPECT imaging.
• To discuss the impact of physical factors and compensation methods on SPECT image quality.
• To highlight the benefits of attenuation compensation in myocardial SPECT for improved clinical diagnosis.

Main Methods:

• Acquisition of multiple 2D planar projection images using scintillation cameras.
• Reconstruction of projection data into 3D SPECT images.
• Application of physical compensation methods for photon attenuation and scatter.

Main Results:

• SPECT provides detailed 3D functional information with improved contrast.
• Attenuation compensation in myocardial SPECT effectively reduces artifacts from non-uniform attenuation.
• Attenuation-compensated SPECT demonstrates potential for reducing false-positive and false-negative myocardial defect detection.

Conclusions:

• SPECT is a powerful diagnostic tool, with ongoing advancements enhancing its capabilities.
• Compensation methods are vital for overcoming image degradation caused by physical factors like attenuation and scatter.
• Future improvements in SPECT will stem from advancements in radiopharmaceuticals, instrumentation, and reconstruction algorithms.