What notable achievement occurred in 1975 related to PET imaging?

What notable achievement occurred in 1975 related to PET imaging?

• A. First handheld PET device
• B. First SPECT scanner
• C. First whole-body PET scanner
• D. First closed-ring transverse positron tomography for PET imaging

Answer: (D)

In PET imaging, forming true cross-sectional pictures depends on collecting data from all around the patient. In 1975 the field achieved a breakthrough with the first closed-ring detector arrangement that surrounded the subject in a complete circle, enabling transverse (cross-sectional) tomography. This closed-ring setup means annihilation photons can be detected from every angle around the body, so the data can be reconstructed into accurate 2D slices rather than just rough projections. That leap from partial or non-ring geometries to a full ring is what makes this milestone so pivotal: it established the practical method for tomographic PET imaging, paving the way for reliable 3D PET imaging later on. The other options refer to different milestones or modalities that came later and do not reflect this initial penetration into true PET tomography.

In PET imaging, forming true cross-sectional pictures depends on collecting data from all around the patient. In 1975 the field achieved a breakthrough with the first closed-ring detector arrangement that surrounded the subject in a complete circle, enabling transverse (cross-sectional) tomography. This closed-ring setup means annihilation photons can be detected from every angle around the body, so the data can be reconstructed into accurate 2D slices rather than just rough projections. That leap from partial or non-ring geometries to a full ring is what makes this milestone so pivotal: it established the practical method for tomographic PET imaging, paving the way for reliable 3D PET imaging later on. The other options refer to different milestones or modalities that came later and do not reflect this initial penetration into true PET tomography.