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Signals

Examples

The description of annotations in future sections make use of the following examples:

  1. "This patient has had a lymph node biopsy which shows melanoma in his right groin. Five out of ten nodes were involved. It is clearly secondaries from the melanoma on his right second toe. Although his PET scan is normal he does need a groin dissection. We will perform a CT scan to look at the left pelvic side wall and I will review him together with Dr. X next week."
  2. "I have discussed her with x. We agreed to treat with DTIC, and then consider radiotherapy."
  3. "This 56 year old woman was admitted to x ward on the date above, with increasing facial pain. This was initially relieved by co-codamol"
  4. "There was no evidence of extra pelvic secondaries"

The signals

The following table describes the CLEF signals. Signals are pieces of text that provide some extra information about an entity, modifying it in some way. For each signal type, the entity type that it modifies is given, together with a brief description and examples.

Signal type Entity modified Description Example
Negation Condition In general, things that are in the text are assumed to exist by the very nature of them being discussed. Sometimes, however, they do not: the text says that they are negative, or absent. In other cases, the text may say that something is unknown or uncertain. Negation signals cater for this, and are used to mark the part of the text that shows absence, negation and uncertainty. Negation signals may have values of absent and uncertain. In example 4, the text "no evidence" signals the absence of the secondaries (more precisely, the absence of any finding of secondaries).
Laterality Locus, Intervention Text that signals the laterality of a Locus or Intervention. May have a value of left, right, bilateral. There are three lateralities in example 1: two rights, and a left
Sub-location Locus Text that signals some division of, or extra information about, a Locus. Takes no specific values. There is a sub-location in example 4: "extra" (as in external to) provides additional information about the locus "pelvis": that really, the text means the area outside of the pelvis.