Forum Summary

X-ray and optical computed tomography (CT) are imaging techniques with the potential to complement each other in clinical settings, and students at MIT are working to design an optical CT scanner that can be combined easily with a traditional x-ray CT scanner.  X-ray CT is a widely used imaging modality that provides precise anatomic information, but the technique requires a relatively large dose of radiation and is unable to detect certain types of tumors in soft tissue.  Optical CT imaging is less widely used and provides less detailed anatomic information, but it requires no dangerous radiation and can be used to identify soft tissue tumors near the surface of the body.  Combining optical imaging with traditional CT scans would allow doctors to obtain functional information about potentially cancerous lesions along with precise anatomic information.  The MIT students have designed a cylindrical optical CT scanner that can be placed in line with the bore of a conventional x-ray CT scanner.  This configuration allows one to obtain optical and x-ray CT images without having to move the patient, enabling the optical and x-ray images to be aligned with a high degree of precision.  The optical scanner itself consists of two rotating rings, each with a light source and a camera.  Due to size limitations, the scanner can only image the head and neck, covering an axial distance of 30 cm.  Using their optical scanner and a traditional x-ray CT scanner, the students were able to align optical and x-ray images with 2-mm accuracy.  They hope that their device will improve the ability of doctors to detect soft tissue tumors in the head and neck.

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