QUASAR™ Penta-Guide Phantom

The QUASAR™ Penta-Guide Phantom is recognized globally as the preferred tool for commissioning and daily testing of Image-Guided Radiotherapy (IGRT) systems. The QUASAR™ Penta-Guide Phantom ensures the accuracy of LINAC-mounted On-Board Imaging (OBI) guidance systems, including KV, MV, and X-ray Volumetric Imaging (XVI) using Cone Beam CT (CBCT).

Its simple and innovative design facilitates intuitive verification of spatial alignment and isocenter coincidence on IGRT and SGRT systems. The addition of an optional Penta-Guide Tilt-Plate provides intuitive verification of 6DoF couch adjustments.  Combined with our included analysis software, Penta-Guide provides detailed image quality metrics that evaluate the performance of your CBCT imaging systems.

    • Cube, 16 cm, acrylic, 5 kg
    • 4 x 4, 10 x 10, and 12 x 12 cm2 light field alignment
    • Laser alignment lines
    • Built-in bubble level
    • Free software available for download
    • Internal imaging and registration markers designed to minimize CT artifacts
    • User’s Guide and cardboard container for storage and handling are included
  • Minimum Software Technical Requirements

    • Standard PC desktop or laptop with Windows 10 or greater
    • 4 GB RAM
    • .NET framework 4.6.1 for client and server
    • Acrobat Reader to view PDF files
  • 100-1009: Penta-Guide Phantom

  • Optional Accessories

    • 500-3501: Hood for Varian Frameless Array or other visual position indicators
    • 500-3503: Penta-Guide Tilt Plate
Download Product Data Sheet


Intuitive Design

QUASAR Penta-Guide’s simple design promotes efficient daily testing to ensure on-board imaging alignment accuracy. The phantom contains a unique system of low-density rings and hollow spheres, enabling intuitive quality assurance while eliminating high-density imaging artifacts.

Workflow Efficiency

Integrate the QUASAR Penta-Guide IGRT phantom into your daily QA routine to perform geometric accuracy tests. Confirm room laser and IGRT targeting accuracy while simultaneously acquiring valuable CBCT image quality data to monitor On Board Imaging performance.


Manufactured to provide 0.25 mm accuracy – guaranteeing a high-calibre tool for your daily QA processes. Perform multiple isocenter coincidence and alignment tests with reliable repeatability and confidence. Visual tolerance features provide accurate determination of pass/fail criteria.

Image Quality Trending

Obtain vital image quality metrics on your CBCT imaging platform to monitor and trend system performance. Automated analysis provides detailed data to troubleshoot imaging problems or suggest preventative maintenance, minimizing system downtime.


Included with every Penta-Guide Phantom is a software package designed to improve the Radiation Therapist (RT) and Physics QA analysis workflow. An emphasis on user-focused software features such as an RT QA checklist, automated image analysis, and performance trending, creates a time-saving and valuable quality assurance system.

Alignment Consistency

Early detection of system alignment problems can be achieved by monitoring the isocenter and on-board imaging performance. Use automated software analysis of imported images or manual daily shift entries to track system trends.

Image Quality Analysis

Use Penta-Guide’s automated analysis software to evaluate image quality metrics and monitor the performance of your LINAC OBI systems. Stats including spatial resolution, Houndsfield unit constancy and noise/contrast ratio can be used to trend CBCT performance.

Daily QA Checklist

Store and track daily QA results with simple pass/fail criteria using the integrated checklists. Designed to improve morning QA workflow for Radiation Therapists, these tools offer the ability to manage all daily QA data in one place.

Visualization Tools

Advanced 2D/3D visualization portal for the analysis of imported data provides a clear visual representation of system performance. Includes the ability to create line profiles and histograms of user-specified ROIs.

Reporting Feature

Penta-Guide software improves clinical workflow by creating custom reports of daily QA procedures. This provides a simple solution for users to communicate daily testing results to the Physics QA team.

Additional Resources

SYKES J R, LINDSAY R, DEAN C J, BRETTLE D S, MAGEE D R and THWAITES D I, Measurement of cone beam CT coincidence with megavoltage isocentre and image sharpness using the QUASAR™ Penta-Guide phantom, Phys Med. Biol. 53 (19), 2008, 5275–93

THORNTON, MICHAEL M., FLYNN, MICHAEL J., Measurement of the spatial resolution of a clinical volumetric computed tomography scanner using a sphere phantom, Medical Imaging 2006: Physics of Medical Imaging. Volume 6142, pp. 707-716 (2006).