High Spatial Resolution Digital Positron Emission Tomography Images With Dedicated Source-to-background Algorithm for...

Area of Science:

• Nuclear Medicine
• Medical Imaging
• Radiochemistry

Background:

• Accurate delineation of gross tumor volume (GTV) is critical for effective radiation therapy planning.
• High spatial resolution digital positron emission tomography (PET) offers potential for improved GTV definition.

Purpose of the Study:

• To assess the effectiveness of the source-to-background ratio (SBR) algorithm using high spatial resolution digital PET for GTV delineation.
• To quantify the accuracy of GTV delineation with varying voxel sizes.

Main Methods:

• Spheres with known volumes were filled with 18F-FDG to simulate varying radioactivity levels.
• PET images were reconstructed with isotropic voxel sizes of 4 mm, 2 mm, and 1 mm.
• Source-to-background ratio (SBR) and percentage threshold (TH) to SUVmax were calculated and correlated using regression analysis.

Main Results:

• Regression equations were derived to relate SBR and TH for each voxel size.
• Mean relative errors between contoured volume (CV) and true volume were 15% for 4 mm, and 7% for 2 mm and 1 mm voxel sizes.
• The SBR algorithm demonstrated reduced contouring errors, particularly with smaller voxel sizes.

Conclusions:

• High spatial resolution digital PET imaging combined with the SBR algorithm is a valuable tool for accurate GTV delineation.
• This technique minimizes contouring errors, enhancing the precision of GTV definition in clinical settings.