SPECT performance evaluation on image of Yttrium 90 - Bremsstrahlung using Monte Carlo simulation

Area of Science:

• Nuclear Medicine
• Medical Imaging Physics
• Computational Physics

Background:

• Yttrium-90 (90Y) is a key radionuclide in Nuclear Medicine, but its high-energy beta emission complicates SPECT imaging dose planning.
• Bremsstrahlung X-rays produced by 90Y beta particles degrade SPECT image quality.

Purpose of the Study:

• To investigate the impact of bremsstrahlung X-rays on SPECT image acquisition using 90Y.
• To evaluate factors affecting SPECT image quality, including collimator type, source-collimator distance, and material composition.

Main Methods:

• Utilized the MCNPX Monte Carlo code for detailed simulations.
• Simulated 90Y point and distributed sources in various phantoms and materials.
• Evaluated bremsstrahlung photon emission and energy deposition in NaI(Tl) detectors with MEGP and LEHR collimators.

Main Results:

• Simulations quantified bremsstrahlung photon emission across different materials and geometries.
• Energy distribution images revealed the influence of collimator type and source-collimator distance.
• The Median Energy General Purpose (MEGP) collimator consistently yielded superior SPECT image resolution.

Conclusions:

• Monte Carlo simulations are crucial for assessing SPECT performance with 90Y.
• The MEGP collimator offers the best resolution for 90Y SPECT imaging, irrespective of source-collimator distance.