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Title: Proof of concept for low-dose molecular breast imaging with a dual-head CZT gamma camera. Part I. Evaluation in phantoms

Abstract

Purpose: Molecular breast imaging (MBI) is a nuclear medicine technology that uses dual-head cadmium zinc telluride (CZT) gamma cameras to image functional uptake of a radiotracer, Tc-99m sestamibi, in the breast. An important factor in adoption of MBI in the screening setting is reduction of the necessary administered dose of Tc-99m sestamibi from the typically used dose of 740 MBq to approximately 148 MBq, such that MBI's whole-body effective dose is comparable to that of screening mammography. Methods that increase MBI count sensitivity may allow a proportional reduction in the necessary administered dose. Our objective was to evaluate the impact of two count sensitivity improvement methods on image quality by evaluating count sensitivity, spatial resolution, and lesion contrast in phantom simulations. Methods: Two dual-head CZT-based MBI systems were studied: LumaGem and Discovery NM 750b. Two count sensitivity improvement methods were implemented: registered collimators optimized for dedicated breast imaging and widened energy acceptance window optimized for use with CZT. System sensitivity, spatial resolution, and tumor contrast-to-noise ratio (CNR) were measured comparing standard collimation and energy window setting [126-154 keV (+10%, -10%)] with optimal collimation and a wide energy window [110-154 keV (+10%, -21%)]. Results: Compared to the standard collimator designs andmore » energy windows for these two systems, use of registered optimized collimation and wide energy window increased system sensitivity by a factor of 2.8-3.6. Spatial resolution decreased slightly for both systems with new collimation. At 3 cm from the collimator face, LumaGem's spatial resolution was 4.8 and 5.6 mm with standard and optimized collimation; Discovery NM 750b's spatial resolution was 4.4 and 4.6 mm with standard and optimized collimation, respectively. For both systems, at tumor depths of 1 and 3 cm, use of optimized collimation and wide energy window significantly improved CNR compared to standard settings for tumors 8.0 and 9.2 mm in diameter. At the closer depth of 1 cm, optimized collimation and wide energy window also significantly improved CNR for 5.9 mm tumors on Discovery NM 750b. Conclusions: Registered optimized collimation and wide energy window yield a substantial gain in count sensitivity and measurable gain in CNR, with some loss in spatial resolution compared to the standard collimator designs and energy windows used on these two systems. At low-count densities calculated to represent doses of 148 MBq, this tradeoff results in adequate count density and lesion contrast for detection of lesions {>=}8 mm in the middle of a typical breast (3 cm deep) and lesions {>=}6 mm close to the collimator (1 cm deep).« less

Authors:
; ;  [1]
  1. Department of Radiology, Mayo Clinic, 200 First Street SW, Rochester, Minnesota 55905 (United States)
Publication Date:
OSTI Identifier:
22098880
Resource Type:
Journal Article
Journal Name:
Medical Physics
Additional Journal Information:
Journal Volume: 39; Journal Issue: 6; Other Information: (c) 2012 American Association of Physicists in Medicine; Country of input: International Atomic Energy Agency (IAEA); Journal ID: ISSN 0094-2405
Country of Publication:
United States
Language:
English
Subject:
60 APPLIED LIFE SCIENCES; BIOMEDICAL RADIOGRAPHY; COLLIMATORS; DOSIMETRY; GAMMA CAMERAS; HEALTH HAZARDS; KEV RANGE 100-1000; MAMMARY GLANDS; NEOPLASMS; NMR IMAGING; PHANTOMS; RADIATION DOSES; SENSITIVITY; SIMULATION; SPATIAL RESOLUTION; TECHNETIUM 99; TRACER TECHNIQUES

Citation Formats

Hruska, Carrie B., Weinmann, Amanda L., and O'Connor, Michael K. Proof of concept for low-dose molecular breast imaging with a dual-head CZT gamma camera. Part I. Evaluation in phantoms. United States: N. p., 2012. Web. doi:10.1118/1.4718665.
Hruska, Carrie B., Weinmann, Amanda L., & O'Connor, Michael K. Proof of concept for low-dose molecular breast imaging with a dual-head CZT gamma camera. Part I. Evaluation in phantoms. United States. https://doi.org/10.1118/1.4718665
Hruska, Carrie B., Weinmann, Amanda L., and O'Connor, Michael K. Fri . "Proof of concept for low-dose molecular breast imaging with a dual-head CZT gamma camera. Part I. Evaluation in phantoms". United States. https://doi.org/10.1118/1.4718665.
@article{osti_22098880,
title = {Proof of concept for low-dose molecular breast imaging with a dual-head CZT gamma camera. Part I. Evaluation in phantoms},
author = {Hruska, Carrie B. and Weinmann, Amanda L. and O'Connor, Michael K.},
abstractNote = {Purpose: Molecular breast imaging (MBI) is a nuclear medicine technology that uses dual-head cadmium zinc telluride (CZT) gamma cameras to image functional uptake of a radiotracer, Tc-99m sestamibi, in the breast. An important factor in adoption of MBI in the screening setting is reduction of the necessary administered dose of Tc-99m sestamibi from the typically used dose of 740 MBq to approximately 148 MBq, such that MBI's whole-body effective dose is comparable to that of screening mammography. Methods that increase MBI count sensitivity may allow a proportional reduction in the necessary administered dose. Our objective was to evaluate the impact of two count sensitivity improvement methods on image quality by evaluating count sensitivity, spatial resolution, and lesion contrast in phantom simulations. Methods: Two dual-head CZT-based MBI systems were studied: LumaGem and Discovery NM 750b. Two count sensitivity improvement methods were implemented: registered collimators optimized for dedicated breast imaging and widened energy acceptance window optimized for use with CZT. System sensitivity, spatial resolution, and tumor contrast-to-noise ratio (CNR) were measured comparing standard collimation and energy window setting [126-154 keV (+10%, -10%)] with optimal collimation and a wide energy window [110-154 keV (+10%, -21%)]. Results: Compared to the standard collimator designs and energy windows for these two systems, use of registered optimized collimation and wide energy window increased system sensitivity by a factor of 2.8-3.6. Spatial resolution decreased slightly for both systems with new collimation. At 3 cm from the collimator face, LumaGem's spatial resolution was 4.8 and 5.6 mm with standard and optimized collimation; Discovery NM 750b's spatial resolution was 4.4 and 4.6 mm with standard and optimized collimation, respectively. For both systems, at tumor depths of 1 and 3 cm, use of optimized collimation and wide energy window significantly improved CNR compared to standard settings for tumors 8.0 and 9.2 mm in diameter. At the closer depth of 1 cm, optimized collimation and wide energy window also significantly improved CNR for 5.9 mm tumors on Discovery NM 750b. Conclusions: Registered optimized collimation and wide energy window yield a substantial gain in count sensitivity and measurable gain in CNR, with some loss in spatial resolution compared to the standard collimator designs and energy windows used on these two systems. At low-count densities calculated to represent doses of 148 MBq, this tradeoff results in adequate count density and lesion contrast for detection of lesions {>=}8 mm in the middle of a typical breast (3 cm deep) and lesions {>=}6 mm close to the collimator (1 cm deep).},
doi = {10.1118/1.4718665},
url = {https://www.osti.gov/biblio/22098880}, journal = {Medical Physics},
issn = {0094-2405},
number = 6,
volume = 39,
place = {United States},
year = {2012},
month = {6}
}