Single Photon Emission Computed Tomography (SPECT) extends planar scintigraphy into three dimensions by acquiring projection data from multiple angles around the patient. Understanding the physics of SPECT is essential for interpreting tomographic radionuclide images and for optimising acquisition and reconstruction parameters in clinical practice.

SPECT imaging relies on rotating gamma camera detectors to collect counts from different projection angles. These projections are reconstructed using filtered back projection or iterative reconstruction algorithms to generate cross-sectional images. Key physical principles include spatial resolution degradation with depth, collimator-dependent resolution, attenuation effects, scatter contamination, and statistical noise. Unlike PET, SPECT relies on physical collimation, which significantly limits sensitivity and introduces resolution trade-offs.

Examinations such as FRCR Part 1 Physics, ABR Core, RANZCR AIT, and FC(Rad) Diag SA frequently test SPECT principles. Common question themes include centre-of-rotation errors, attenuation correction, resolution recovery, reconstruction filters, contrast versus noise trade-offs, and the physical limitations imposed by parallel-hole, converging, and pinhole collimators. Understanding these concepts is crucial for recognising artefacts and optimising image quality.

This section contains structured board-level questions covering SPECT acquisition geometry, detector rotation, reconstruction techniques, resolution limitations, attenuation and scatter correction, and artefact recognition. The questions are designed to reinforce both theoretical understanding and clinically relevant interpretation skills in radionuclide imaging.

For more in depth questions and answers, get access to over 2,000 board-level radiology physics questions with highly detailed explanations, structured feedback, and exam-focused learning tools. Explore the complete question bank here.