Daily Cone Beam CT QA

The QUASAR™ Penta-Guide phantom is used for the commissioning and daily testing of Image-Guided Radiotherapy (IGRT) systems. The Penta-Guide ensures the accuracy of linac-mounted image guidance systems, including cone beam CT (CBCT), x-ray volumetric imaging (XVI) and on-board imaging (OBI). Using low-density objects to minimize imaging artefacts, the Penta-Guide allows rapid and easy daily testing for:

• 3D cone beam registration
  
• kV and MV system coincidence
  
• kV and MV projection images
  
• Laser and light field coincidence
  
• Remote table adjustments

Used by a therapist every morning, testing takes little or no extra time and can be
completed during normal daily equipment warm-up procedures. Ideally, one
Penta-Guide phantom should be used per linac allowing simultaneous system testing
and preventing unnecessary start-up delays.

The Penta-Guide also comes with a Lehmann Yoke for confirmation of the source to surface distance (SSD). A protocol outlining this enhanced testing procedure is included with the User’s Guide. (Photo provided by Joerg Lehmann)

An optional Hood is used to confirm that the Varian Frameless Array or other visual position indicator is aligned with the CBCT and OBI.