Design and Evaluation of Simulated PEM Scanner for EarlyStage Breast Lesion Detection
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Date
2022-06
Authors
Journal Title
Journal ISSN
Volume Title
Publisher
Addis Ababa University
Abstract
Breast cancer is the most commonly diagnosed cancer in females worldwide,
contributing around 11.7 % (~2.3 million people) of new cancer cases in 2020 only,
with a death rate of 6.9%. Early diagnosis and check-up are essential for effective
treatment and reduction of incidences and mortality rates. Different modalities exist to
diagnose breast cancers. Positron emission tomography (PET) is the one imaging tool
in nuclear medicine providing physiological information about the breast by
quantifying the metabolic activities of the cells in the breast tissues. Both whole-body
(WB) PET scanners and organ-specific PET scanners are available in the market. But
current trends show that there is a complete shift towards dedicated, organ specific
PETs. One of those is Positron Emission Mammography (PEM), believed to be better
than mammography and other imaging modalities to detect small breast lesions.
Semiconductor-based PEM detectors are simulated with good spatial resolution but are
expensive. Scintillator-based PET and PEM detectors can provide quit good sensitivity
and are cost effective. On the contrary, these detectors cannot detect small breast lesions
due to their poor spatial resolution. This requires development of detectors that give
rise to better spatial resolution. In the current thesis work, a high-performance PEM
scanner is simulated using TOC (Transparent Optical Ceramic) scintillators of 1 x 1 x
10mm
3
crystals with the aim to improve the spatial resolution, sensitivity as well as
scattering fraction. Those TOC scintillators are LHO: cerium doped lutetium hafnate
(Lu
2
Hf
2
O
7
: Ce), BHO: cerium doped barium hafnate (BaHfO
3
: Ce) and SHO: cerium
doped strontium hafnate (SrHfo
3
: Ce). The design was based on the GATE (Geant4
Application for Emission Tomography) simulation software. Its performance was
tested and evaluated by following the NEMA (National Electrical Manufacturers
Association) NU 4-2008 standards. The complete scanner has 39 heads and 10 x 30 x
59 modules in the detector. Based on the type of scintillator used, the designed scanner
provided a spatial resolution between 1.0 and 1.1 mm FWHM (Full Width at Half
Maximum) in the axial direction, 7.24% to 9.11% system sensitivity and 11.01% to
11.19% scatter fraction. The design offered good uniformity as well as image quality.
The computed spatial resolution, sensitivity and scatter fraction values are superior to
those already reported in the literature.
Description
Keywords
Breast Cancer, GATE, PEM, PET, Semiconductor, Scintillator, TOCs, NEMA standard