The flood field is used by AQA to create a PSM (Pixel Sensitivity Matrix). Treatment machines create a new flood field when an EPID recalibration is performed. This procedure allows users to upload their latest flood field to AQA. This is often done as a prelude to uploading a PSM.
A flood field may also be uploaded with the PSM files.
The flood field consists of a single DICOM image with modality RTIMAGE. However, while RTIMAGE files generally contain a DICOM Device Serial Number (0018,1000) the flood field does not. Because of this you must specify which machine the file comes from.
From the home page, click the Run Procedure link and then Flood Field. This will show the upload page.
Drag and drop a flood field file into the drop area, select the machine, and click Run.
A page similar to the one below will be shown. Note that the windowing/leveling of the image has been adjusted to provide maximum contrast for the area that excludes the corners.
