A Method for Validating PET and SPECT Cameras for Quantitative Clinical Imaging Trials Using Novel Radionuclides

Area of Science:

• Nuclear Medicine
• Medical Imaging
• Radiochemistry

Background:

• Quantitative accuracy and quality assurance are critical for Positron Emission Tomography (PET) and Single-Photon Emission Computed Tomography (SPECT) in clinical trials.
• Standard calibration protocols often rely on radionuclides like Fluorine-18, necessitating new methods for nonstandard radionuclides, particularly those with longer half-lives.

Purpose of the Study:

• To develop and report a methodology for calibrating and verifying the quantitative accuracy and quality assurance of PET and SPECT imaging systems.
• To adapt these methods for use with nonstandard radionuclides, specifically those with longer half-lives, in the context of clinical imaging trials.

Main Methods:

• A three-step calibration protocol was implemented: verification with a standard radionuclide, testing the novel radionuclide in a simple geometry, and assessment in a complex geometry using the NEMA NU-2 IEC image-quality phantom.
• The methodology was exemplified using Iodine-124 (PET) and Iodine-131 (SPECT), requiring whole-body tomographic imaging with low-dose CT.
• PET system calibration involved dose calibrator adjustments for non-standard radionuclides, while SPECT calibration used independent sensitivity measurements at a core laboratory.

Main Results:

• Seven Australian sites successfully qualified 10 PET/CT scanners for Iodine-124 imaging and 8 SPECT/CT systems for Iodine-131 imaging.
• One PET/CT system exceeded the specified quantitative accuracy (SUVavg of 1.0 ± 0.05).
• All qualified SPECT/CT systems achieved quantitative accuracy within ±10% of the true radioactivity concentration.

Conclusions:

• A generalizable methodology for calibrating and validating PET and SPECT systems for quantitative imaging in clinical trials has been successfully established.
• The developed procedures are relatively simple and can be implemented by on-site staff with equipment provided by clinical trials organizations.
• This approach enhances the reliability of quantitative imaging data in clinical trials using a wider range of radionuclides.