Detection of colon cancer by continuous-wave terahertz polarization imaging technique

We demonstrate a reflective, continuous-wave terahertz (THz) imaging system to acquire ex vivo images of fresh human colonic excisions. Reflection measurements of 5-mm-thick sections of colorectal tissues were obtained using a polarization-specific detection technique. Two-dimensional THz reflection images of both normal and cancerous colon tissues with a spatial resolution of 0.6 mm were acquired using an optically pumped far-infrared molecular gas laser. Good contrast has been observed between normal and tumorous tissues at 584 GHz frequency. The resulting THz reflection images compared with the tissue histology showed a correlation between cancerous region and increased reflection. We hypothesize that the imaging system and polarization techniques are capable of registering reflectance differences between cancerous and normal colon. However, further investigations are necessary to completely understand the source mechanism behind the contrast and confirm the hypothesis; if true, it likely represents the first continuous-wave THz reflection imaging technique to show sufficient contrast to identify colon tumor margins. Also, it may represent a significant step forward in clinical endoscopic application of THz technology to aid in in vivo colorectal cancer screening.