As a consequence of emerging clinical needs and general terminology maintenance and enhancement, terminology producers will be required to author clinical meanings to be included as precoordinated concepts in either the International Edition of SNOMED CT or a SNOMED CT Extension.
Expression templates are Expression templates can be used to author precoordinated clinical meanings by providing reusable patterns for the precoordination of clinical meanings, because they can specify the restricted definition of similar concepts. Expression templates can define the set of attributes and attribute ranges used in the creation of specific concepts. SNOMED CT expression templates can therefore assist SNOMED CT authors in creating concepts with predefined constraints, and they can enable the creation of batches of concepts or their updates.Using values that may be used to define concepts in a specific hierarchy or subhierarchy, thereby assisting SNOMED CT authors to create concepts in a consistent way. They can also be used together with an input file to either create or update batches of concepts very efficiently. Using expression templates to author SNOMED CT concepts helps can help to improve the quality of the terminology because templates can support the consistent definition and representation of concepts of the same type. As a result, expression templates , by controlling the consistency of the definitions, and by validating concept definition against appropriate templates. Similarly, they can also be used as a metrics for the measurement of qualitymetric to measure the quality of given subhierarchy.
In summary, Expression Templates expression templates can be used by terminology authors to:
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- , or a batch of concepts;
- Update the definition of a concept (or batch of concepts) to conform to a particular
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- ;
- Validate the definition of concept or a set of concepts;
- Define quality metrics for a particular subhierarchy.
The table below shows an expression template that may be used to define computed tomography (CT) concepts of a particular body site (e.g. CT of right arm). The 'bodysite' slot represents the placeholder, which is subsequently replaced with a specific body site concept to form a complete concept definition.
| Template (diagram) | Template (syntax) |
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 Image Modified
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| Scg expression |
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71388002 |Procedure|:
{ |
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[[+id @bodysite]],
260686004 |Method| = |
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The following table shows the
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expressions that result when processing the template using a specific slot value:
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| bodysite | Resulting Expression |
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| Concept |
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| t | 48979004 | Structure of left lower leg (body structure) | |
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| Scg expression |
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71388002 |Procedure|:
{ |
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363704007 |Procedure site| = 48979004 | |
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Structure of left lower leg |
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| Concept |
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| t | 368209003 | Right upper arm structure (body structure) | |
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260686004 |Method| = 312251004 |Computed tomography imaging action |
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Alternative representation of the same example:
If the following values are provided to complete the slot:
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| Concept |
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| t | 368209003 | Right upper arm structure (body structure) | |
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| Scg expression |
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71388002 |Procedure|:
{ |
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363704007 |Procedure site| = |
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260686004 |Method| = 312251004 |Computed tomography imaging action |
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