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Vista Clipped

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 optical CT scanner 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.

Key Features

  • Acquisition, reconstruction, and display of dose distributions in less than an hour
  • Works with radiochromic dosimeters such as Fricke gels
  • Capable of scanning objects up to 15 cm diameter by 12 cm long
  • Simple on-screen controls and straightforward workflow
  • Compatible with Windows XP and Vista operating systems
  • Data is fully accessible for research applications
  • Comprehensive verification of the intricate dose distributions associated with advanced radiation treatments is now an immediate and substantial problem.
    Mark Oldham, PhD, FAAPM // Professor of Radiation Oncology, Duke University Medical Center
  • …the rapid advances in the technology to deliver radiation treatments have not been paralleled by corresponding advances in the ability to verify these treatments.
    Mark Oldham, PhD, FAAPM // Professor of Radiation Oncology, Duke University Medical Center

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.


Typical Scanning Laser Systems:

Vista Optical CT Scanner:

Scanning Time
6 minutes per slice Less than 5 minutes for 360 projections, up to 400 slices
Reconstruction Time
6 minutes per slice Less than 5 minutes for 100 slices
Spatial Resolution
0.5 mm, non isotropic 2.0, 1.0, 0.5, 0.25 mm, isotropic
Overall Time to Results
4 hours – 1 day or more Less than 1 hour

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


Modus QA is providing support for researchers to further the development of gel dosimetry for clinical applications. We have a limited supply of TruView™ 3D Gel Dosimeters which we are offering free of charge to qualified researchers*.

*To qualify for 3D Dosimetry Research Support you must have:

  • An optical CT scanner with wavelength 585 - 590 nm
  • A refrigerator to store gels
  • Refractive index matching liquid (8% propylene glycol and water or equivalent)
  • Access to clinical radiotherapy systems
  • Resources to complete experiments within 30 days of receipt of a shipment of gels
  • Ability to analyze and present results (prior publications in 3D dosimetry)
  • An experiment plan, preferably with a clinical focus

Modus QA supports all forms of dissemination of results. We will not attempt to block or interfere with publication or communication of results in any way. All we ask in return is a copy of your results, whether published or not, and we request your feedback regarding gel and scanner performance on a timely basis.

We look forward to supporting your research towards making 3D dosimetry a clinical standard.

Apply Now +


Modus QA is pleased to announce the introduction and commercial supply of a new radiochromic gel for research into 3D dosimetry.

TruView™ 3D Gel Dosimeters are stable, fast and reusable.

Based on the well known Ferrous-Xylenol Orange radiochemistry, the enhanced TruView™ 3D Gel Dosimeters are stable for up to 30 days, can be reused multiple times and are designed for multiple Radiotherapy applications including IMRT, VMAT, SRS and SBRT.

TruView™ 3D Gel Dosimeters are compatible with the Vista Optical CT Scanner available from Modus QA. They can also be scanned using other optical CT geometries as well.

Read More +


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