Effect of the source and detector configuration on the detectability of breast cancer

Breast cancer causes the death of more than 150,000 women in the United States each year. Pregnant women cannot undergo mammography due to its dangerous side effects and, for younger women, a mammogram does not differentiate tumor from their dense breast tissue. Breast tumors usually become a localized absorber in the near infrared (NIR) wavelength region, because of the increased hemoglobin concentration around the area of the tumor. Therefore, NIR has a high potential to detect breast cancer without side effects. A computer simulation solving the photon transfer equation was used to study the detectability of various tumor sizes embedded in the breast model at various depths, for both reflectance and transmittance. Previous reflectance studies demonstrated that increasing the S-D separation does not necessarily allow the photons to penetrate deeper in the medium. The optimum S-D separation for breast tissue was found to be 3.0 cm, where the light penetrates up to 1.7 cm. Studies on the photon path in transmittance demonstrate that, at high modulation frequencies, (e.g. 1.0 GHz), the photon path becomes more coherent. Therefore, for transmittance measurements, high modulation frequencies can be useful to localize deep tumors. Multi frequency, multi- S-D separation reflectance can be used to provide information on tumor depth.