Breast cancer diagnosis using neutron stimulated emission computed tomography: Dose and count requirements

Neutron Stimulated Emission Computed Tomography (NSECT) was evaluated as a potential technique for breast cancer diagnosis. NSECT can form a 3D tomographic image with an elemental (isotopic) spectrum provided at each reconstructed voxel. The target is illuminated (in vivo) by a neutron beam that scatters in-elastically producing characteristic gamma emission that is acquired tomographically with a spectrograph. Images are reconstructed of each element in the acquired spectrum. NSECT imaging was simulated for benign and malignant breast masses. A range of the number of incident neutrons was simulated from 19 million to 500k neutrons. Simulation included all known primary and secondary physical interactions in both the breast as well as in the spectrometer. Characteristic energy spectra were acquired by simulation and were analyzed for statistically significant differences between benign and malignant breasts. For 1 million incident neutrons, there were 61 differences in the spectra that were statistically significant (p < 0,05), Of these, 23 matched known characteristic emission from 6 elements that have been found in the breast (Br, Cs, K, Mn, Rb, Zn). The dose to two breasts was less than 3% of the dose of a 4 view screening mammogram, Increasing the dose to 52% of the mammogram (19 million neutrons) provided 89 significant spectral differences that matched 30 known emissions from 7 elements that have been found in the breast (Br, Co, Cs, K, Mn, Rb, Zn). Decreasing the dose to 1.4% (500K neutrons) eliminated all statistically significant matches to known elements. This study suggests that NSECT may be a viable technique for detecting human breast cancer in vivo at a reduced dose compared to 4 view screening mammography.