Winston-Lutz 3D

Full 3D isocentre analysis from multi-angle EPID images, sub-millimetre precision.

EPID images (ZIP of DICOM files)

All the Winston-Lutz images of the session (gantry, collimator, couch angles) in one ZIP.

Analysis parameters

BB diameter (mm)

Nominal diameter of the ball bearing (1 – 30 mm).

Tolerance: max CAX to BB (mm)

Largest 2D deviation allowed on any image.

Tolerance: gantry 3D isocentre diameter (mm)

Diameter of the smallest sphere containing the gantry isocentres. Adapt to your protocol.

Low-density BB

The BB appears darker than the field (e.g. air or plastic marker).

Open field (focus on the EPID)

Use the image centre instead of a detected MLC/jaw field.

Align the BB with the radiation isocentre

Virtually shift the BB to the radiation isocentre before computing the deviations.

Author (report)

Comment (report)

Engine: pylinac WinstonLutz. Your files are deleted within one hour. Do not upload identifiable patient data.

Analysing the images…

No analysis yet.

Upload a ZIP of EPID images, or run the demo session, to see the results here.

How it works

Acquire EPID images of the BB at several gantry, collimator and couch angles, export them as DICOM and put them in one ZIP.
pylinac finds the radiation field centre (CAX) and the BB on every image, then sorts the images by moving axis from their DICOM headers.
You get the 2D deviations per image, the isocentre size of each axis, and the shift that brings the BB to the radiation isocentre.