Simultaneous emission and attenuation reconstruction in time-of-flight PET using a reference object

Area of Science:

• Medical Imaging
• Nuclear Medicine
• Positron Emission Tomography (PET)

Background:

• Simultaneous reconstruction of emission and attenuation images in time-of-flight positron emission tomography (TOF-PET) lacks a unique solution.
• This limitation hinders accurate image reconstruction without supplementary data.
• External imaging modalities like CT, MRI, or transmission scans are typically required for attenuation correction.

Purpose of the Study:

• To address the non-uniqueness issue in TOF-PET image reconstruction.
• To develop a method for obtaining accurate attenuation maps using only TOF-PET data.
• To investigate the use of an external reference object with known attenuation.

Main Methods:

• Simultaneous reconstruction of emission and attenuation images was performed.
• A reference object with known attenuation was placed outside the patient.
• Various configurations (geometry, material, activity) of the reference object were evaluated.
• The optimal configuration was tested under different timing resolutions and noise levels using Monte Carlo simulations.

Main Results:

• An optimal configuration involved a water cylinder filled with activity, placed within the patient table.
• This configuration achieved mean differences below 10% between reconstructed and true images.
• Increasing the activity of the reference object further improved reconstruction accuracy.
• Simulations incorporated noise using Monte Carlo techniques based on PET/CT data.

Conclusions:

• The proposed strategy shows promise for accurate attenuation mapping using pure TOF-PET data.
• This method may eliminate the need for CT, MRI, or transmission scans for attenuation correction.
• The study provides a potential pathway for enhanced quantitative accuracy in TOF-PET imaging.