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Michael Ljungberg

Michael Ljungberg

Professor

Michael Ljungberg

Modelling of energy-dependent spectral resolution for SPECT Monte Carlo simulations using SIMIND

Författare

  • Michaella Morphis
  • Johan A. van Staden
  • Hanlie du Raan
  • Michael Ljungberg

Summary, in English

Monte Carlo (MC) modelling techniques have been used extensively in
Nuclear Medicine (NM). The theoretical energy resolution relationship (∝1/E−−√),
does not accurately predict the gamma camera detector response across
all energies. This study aimed to validate the accuracy of an energy
resolution model for the SIMIND MC simulation code emulating the Siemens
Symbia T16 dual-head gamma camera.MethodsMeasured
intrinsic energy resolution data (full width half maximum (FWHM)
values), for Ba-133, Lu-177, Am-241, Ga-67, Tc-99m, I-123, I-131 and
F-18 sources in air, were used to create a fitted model of the energy response of the gamma camera. Both the fitted and theoretical models
were used to simulate intrinsic and extrinsic energy spectra using
three different scenarios (source in air; source in simple scatter
phantom and a clinical voxel-based digital patient phantom).ResultsThe results showed the theoretical model underestimated the FWHM values at energies above 160.0 keV up to 23.5 keV. In contrast, the fitted model
better predicted the measured FWHM values with differences less than
3.3 keV. The I-131 in-scatter energy spectrum simulated with the fitted model
better matched the measured energy spectrum. Higher energy photopeaks,
(I-123: 528.9 keV and I-131: 636.9 keV) simulated with the fitted model, more accurately resembled the measured photopeaks. The voxel-based digital patient phantom energy spectra, simulated with the fitted and theoretical models, showed the potential impact of an incorrect energy resolution model when simulating isotopes with multiple photopeaks.ConclusionModelling of energy resolution with the proposed fitted model
enables the SIMIND user to accurately simulate NM images. A great
improvement was seen for high-energy photon emitting isotopes (e.g.
I-131), as well as isotopes with multiple photopeaks (e.g. Lu-177, I-131
and Ga-67) in comparison to the theoretical model. This will result in accurate evaluation of radioactivity quantification, which is vital for dosimetric purposes.

Avdelning/ar

  • Nuclear Medicine Physics

Publiceringsår

2021

Språk

Engelska

Publikation/Tidskrift/Serie

Heliyon

Volym

7

Issue

2

Dokumenttyp

Artikel i tidskrift

Förlag

Elsevier

Ämne

  • Radiology, Nuclear Medicine and Medical Imaging
  • Other Physics Topics

Nyckelord

  • Energy resolution
  • Energy spectrum
  • Monte Carlo simulation
  • Multiple photopeak isotope

Aktiv

Published

Forskningsgrupp

  • Nuclear Medicine Physics

ISBN/ISSN/Övrigt

  • ISSN: 2405-8440