Breast cancer detection using neutron stimulated emission computed tomography: Prominent elements and dose requirements

Abstract

Neutron stimulated emission computed tomography (NSECT) is being developed to noninvasively determine concentrations of trace elements in biological tissue. Studies have shown prominent differences in the trace element concentration of normal and malignant breast tissue. NSECT has the potential to detect these differences and diagnose malignancy with high accuracy with dose comparable to that of a single mammogram. In this study, NSECT imaging was simulated for normal and malignant human breast tissue samples to determine the significance of individual elements in determining malignancy. The normal and malignant models were designed with different elemental compositions, and each was scanned spectroscopically using a simulated 2.5 MeV neutron beam. The number of incident neutrons was varied from 0.5 million to 10 million neutrons. The resulting gamma spectra were evaluated through receiver operating characteristic (ROC) analysis to determine which trace elements were prominent enough to be considered markers for breast cancer detection. Four elemental isotopes (133Cs, 81Br, 79Br, and 87Rb) at five energy levels were shown to be promising features for breast cancer detection with an area under the ROC curve (A(Z)) above 0.85. One of these elements--87Rb at 1338 keV--achieved perfect classification at 10 million incident neutrons and could be detected with as low as 3 million incident neutrons. Patient dose was calculated for each gamma spectrum obtained and was found to range from between 0.05 and 0.112 mSv depending on the number of neutrons. This simulation demonstrates that NSECT has the potential to noninvasively detect breast cancer through five prominent trace element energy levels, at dose levels comparable to other breast cancer screening techniques.

Modeling the adult female phantom in the supine and prone postures and initial dose assessment in breast cancer diagnosis with Neutron Stimulated Emission Computed Tomography

“…The average energy deposition in the breast of the Ref-MOB phantom is 0.5 MeV per emitted neutron. However, the maximum deposited energy is 0.82 MeV per one emitted neutron, which has good agreement with the deposited energy calculated by Bender et al (2007). Figure 5 displays the averaged absorbed dose of adipose and glandular tissues in 9 rotation angles at different steps of beam translation.…”

Design and Development of a High-Energy Gamma Camera for Use With NSECT Imaging: Feasibility for Breast Imaging

“…These issues include, but are not limited to: dose, quantity of trace elements necessary to distinguish between malignant and benign tissue and development of a position sensitive gamma camera. We are currently investigating these issues [1], [31], [32].…”

Dual-energy contrast-enhanced breast tomosynthesis: optimization of beam quality for dose and image quality

“…Prior publications provided the elemental compositions of the phantom and system materials in the simulation model including the adipose tissue, ductal tissue, skin, pyrex, selenium, 18 glandular tissue, and malignant masses infused with 1% iodine (Table I). 19 The full phantom was used for the Monte Carlo simulations, while a reduced version that only incorporated the glandular tissue, adipose tissue, and iodinated mass was used for the ray-tracing algorithm. Based on previous research on the relationship between glandular fraction and compressed breast thickness for a 4 cm breast, 20-22 an average glandular fraction of 60% was chosen.…”