Segmentation

Segmentation in Prism is optional. Not every site enables it. It needs segmentable data and the right permissions. When it is present, a Segment toolbar group controls brushes, segment groups, and visibility.

Who this is for

Research and teaching cases where a quick manual mask is enough. Multidisciplinary boards that need a region of interest highlighted before a screenshot. Verification of auto-segmented inputs when DICOM-SEG arrives in a deployment that supports it. Regulatory contouring for radiotherapy planning usually stays on a dedicated TPS. Treat Prism as viewer-first unless your organization qualifies it for more.

Groups and tools

The viewer keeps groups of segments with an active group, names, and on or off visibility. You can add segments when the UI allows, toggle the whole overlay, and sometimes import or lock protected content. Marking a VOI for a resident before conference is a common path. Naming spleen and liver as separate segments in one group, then hiding spleen for a liver-only check, is another.

Brush and eraser paint volumetric or slice-wise depending on viewport kind and engine state. Some operations only apply in volume or MPR cells. If tools are disabled, the active viewport may be stack-only or the study may lack a loadable volume.

Use an MPR or 3D-friendly layout before you fight disabled brushes. Use measurements when you need a length or ROI instead of a painted region.

Segmentations stay in your browser. Horizon follow does not send them to another reader. Lite is the same: local only.