Table 3.

Point of interest (POI) naming conventions and method of creation

POI name	Definition	Method of creation
Plan iso	Treatment plan isocentre = localisation of isocentre on linac prior to online IGRT	The treatment plan isocentre. POI attached to planning CT scan during plan generation
CBCTmidpt	Half‐way between coordinates of first and last slice in x, y and z dimensions of the CBCT image	POI manually added to the CBCT image once imported to Pinnacle3 that equates to the mid‐point of the image
FMmidpt	The mid‐point of the imaged position of the anterior and right and left lateral fiducial markers on the CBCT image	POIs automatically placed in the middle of threshold‐based contours the FMs
AcqIsocenter	The linac isocentre during CBCT acquisition	POI automatically created and associated with the CBCT image when DICOM‐RT RS file imported
InitLaserIso	The position of the linac isocentre prior to CBCT scan initialisation	POI automatically created and associated with the CBCT image when DICOM‐RT RS file imported
InitMatchIso	The position of linac isocentre after CBCT acquisition, just prior to online image matching	POI automatically created and associated with the CBCT image when DICOM‐RT RS file imported