Type Alias: MeasurementTargetPredicate()

MeasurementTargetPredicate: (candidate, options) => boolean

A per-candidate decider: returns true to keep a single candidate display set as a measurement target, false to drop it. Set it on the tool configuration as targetPredicate to narrow the targets the targetsFilter chooser considers - for example targetPredicate: measurementTargetFilters.forModality('PT') restricts a fusion viewport's measurements to its PT volume.

A predicate is the simple half of the selection: it decides one candidate at a time and is reused by whichever chooser is configured, so the same forModality('PT') predicate yields "the first PT" under MeasurementTargetsFilter firstPixelData and "every PT" under allPixelData, without the predicate knowing how many are wanted.

The decision should be based on the modality of the display set where available; candidates whose display set is unknown (eg legacy stack image ids) have no imageIds/instance, letting the predicate choose whether to include them.

import { measurementTargetFilters } from '@cornerstonejs/tools';

// Only measure PT on a fusion viewport
toolGroup.addTool(CircleROITool.toolName, {
  targetPredicate: measurementTargetFilters.forModality('PT'),
});
// Custom predicate
toolGroup.addTool(CircleROITool.toolName, {
  targetPredicate: (candidate) => candidate.modality === 'PT',
});