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Sechopoulos I, Dance DR, Boone JM, Bosmans HT, Caballo M, Diaz O, van Engen R, Fedon C, Glick SJ, Hernandez AM, Hill ML, Hulme KW, Longo R, Rabin C, Sanderink WBG, Seibert JA. Joint AAPM Task Group 282/EFOMP Working Group Report: Breast dosimetry for standard and contrast-enhanced mammography and breast tomosynthesis. Med Phys 2024; 51:712-739. [PMID: 38018710 DOI: 10.1002/mp.16842] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/25/2023] [Revised: 09/26/2023] [Accepted: 11/10/2023] [Indexed: 11/30/2023] Open
Abstract
Currently, there are multiple breast dosimetry estimation methods for mammography and its variants in use throughout the world. This fact alone introduces uncertainty, since it is often impossible to distinguish which model is internally used by a specific imaging system. In addition, all current models are hampered by various limitations, in terms of overly simplified models of the breast and its composition, as well as simplistic models of the imaging system. Many of these simplifications were necessary, for the most part, due to the need to limit the computational cost of obtaining the required dose conversion coefficients decades ago, when these models were first implemented. With the advancements in computational power, and to address most of the known limitations of previous breast dosimetry methods, a new breast dosimetry method, based on new breast models, has been developed, implemented, and tested. This model, developed jointly by the American Association of Physicists in Medicine and the European Federation for Organizations of Medical Physics, is applicable to standard mammography, digital breast tomosynthesis, and their contrast-enhanced variants. In addition, it includes models of the breast in both the cranio-caudal and the medio-lateral oblique views. Special emphasis was placed on the breast and system models used being based on evidence, either by analysis of large sets of patient data or by performing measurements on imaging devices from a range of manufacturers. Due to the vast number of dose conversion coefficients resulting from the developed model, and the relative complexity of the calculations needed to apply it, a software program has been made available for download or online use, free of charge, to apply the developed breast dosimetry method. The program is available for download or it can be used directly online. A separate User's Guide is provided with the software.
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Affiliation(s)
- Ioannis Sechopoulos
- Radboud University Medical Center, Nijmegen, The Netherlands
- Dutch Expert Centre for Screening (LRCB), Nijmegen, The Netherlands
- University of Twente, Enschede, The Netherlands
| | - David R Dance
- National Co-ordinating Centre for the Physics of Mammography (NCCPM), Royal Surrey County Hospital, Guildford, UK
| | - John M Boone
- University of California, Davis, California, USA
| | | | - Marco Caballo
- Radboud University Medical Center, Nijmegen, The Netherlands
| | | | - Ruben van Engen
- Dutch Expert Centre for Screening (LRCB), Nijmegen, The Netherlands
| | - Christian Fedon
- Radboud University Medical Center (now at Nuclear Research and Consultancy Group, NRG), Nijmegen, The Netherlands
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Abstract
PURPOSE This paper evaluates the effects of computed tomography (CT) image noise and artifacts on quantitative single-photon emission computed-tomography (SPECT) imaging, with the aim of establishing an appropriate range of CT acquisition parameters for low-dose protocols with respect to accurate SPECT attenuation correction (AC). METHODS SPECT images of two geometric and one anthropomorphic phantom were reconstructed iteratively using CT scans acquired at a range of dose levels (CTDIvol = 0.4 to 46 mGy). Resultant SPECT image quality was evaluated by comparing mean signal, background noise, and artifacts to SPECT images reconstructed using the highest dose CT for AC. Noise injection was performed on linear-attenuation (μ) maps to determine the CT noise threshold for accurate AC. RESULTS High levels of CT noise (σ ∼ 200-400 HU) resulted in low μ-maps noise (σ ∼ 1%-3%). Noise levels greater than ∼ 10% in 140 keV μ-maps were required to produce visibly perceptible increases of ∼ 15% in (99m)Tc SPECT images. These noise levels would be achieved at low CT dose levels (CTDIvol = 4 μGy) that are over 2 orders of magnitude lower than the minimum dose for diagnostic CT scanners. CT noise could also lower (bias) the expected μ values. The relative error in reconstructed SPECT signal trended linearly with the relative shift in μ. SPECT signal was, on average, underestimated in regions corresponding with beam-hardening artifacts in CT images. Any process that has the potential to change the CT number of a region by ∼ 100 HU (e.g., misregistration between CT images and SPECT images due to motion, the presence of contrast in CT images) could introduce errors in μ140 keV on the order of 10%, that in turn, could introduce errors on the order of ∼ 10% into the reconstructed (99m)Tc SPECT image. CONCLUSIONS The impact of CT noise on SPECT noise was demonstrated to be negligible for clinically achievable CT parameters. Because CT dose levels that affect SPECT quantification is low (CTDIvol ∼ 4 μGy), the low dose limit for the CT exam as part of SPECT/CT will be guided by CT image quality requirements for anatomical localization and artifact reduction. A CT technique with higher kVp in combination with lower mAs is recommended when low-dose CT images are used for AC to minimize beam-hardening artifacts.
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Affiliation(s)
- K W Hulme
- Department of Imaging Physics, The University of Texas M.D. Anderson Cancer Center, Houston, Texas 77030 and The University of Texas Graduate School of Biomedical Sciences, Houston, Texas 77030
| | - S C Kappadath
- Department of Imaging Physics, The University of Texas M.D. Anderson Cancer Center, Houston, Texas 77030 and The University of Texas Graduate School of Biomedical Sciences, Houston, Texas 77030
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