Cone Beam Optical CT Scanner
	Designed for 3D dosimetry in advanced radiotherapy Existing laser scanners are slow, complicated and not clinically practical. Sparsely sampled 2D detector arrays do not provide enough points for confidence in 3D. Physicists need a simple, reliable, geometrically accurate and dosimetrically accurate measurement solution.

Vista™ is a clinically viable solution currently used for research into 3D dosimeters, including radiochromic gels and solids. When 3D dosimeters become clinically viable and commercially available, physicists will have a full 3D dosimetry solution.

For Research in 3D Dosimetry for Radiotherapy

Vista™ reconstructs a 3D map of optical attenuation coefficients within an object suspended in the scanner’s region of interest. This is done by capturing a series of 2D optical projections through the region of interest while the object is being rotated and then using Feldkamp-filtered back projection to construct the 3D map. The base system is designed to work with radiochromic dosimeters such as Fricke gels which have an absorption peak at 590 nm. Different wavelengths are available on request for different dosimeters and for different applications.

Vista™ is capable of scanning objects up to 15 cm diameter by 12 cm long. Objects are suspended in a liquid filled aquarium to provide index of refraction matching. Software is included for scanning, reconstruction and display. Data is fully accessible for research applications.

1. M. Oldham, J. H. Siewerdsen, S. Kumar, J. Wong and D. A. Jaffray; Optical-CT gel-dosimetry I: Basic investigations, Med. Phys. 30, 623-634, 2003