DICOM PS3.3 2021b - Information Object Definitions

C.8.2.2.2 Multi-energy CT X-Ray Detector Macro (Current)
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##### C.8.2.2.2 Multi-energy CT X-Ray Detector Macro

Attributes for the CT X-Ray Detector(s).

Table C.8.2.2-3. Multi-energy CT X-Ray Detector Macro Attributes

Attribute Name | Tag | Type | Attribute Description
--- | --- | --- | ---
Multi-energy CT X-Ray Detector Sequence | (0018,936F) | 1 | X-Ray Detector (see Section C.8.2.2.1.1) information. One or more Items shall be included in this Sequence.
>X-Ray Detector Index | (0018,9370) | 1 | Identification number of this item in the Multi-energy CT X-Ray Detector Sequence. The number shall be 1 for the first Item and increase by 1 for each subsequent Item.
>X-Ray Detector ID | (0018,9371) | 1 | Identifier of the physical X-Ray detector. This might be the serial number. When a single detector discriminates different energies, the X-Ray Detector ID (0018,9371) will have the same value in different Items of Multi-energy CT X-Ray Detector Sequence (0018,936F).
>Multi-energy Detector Type | (0018,9372) | 1 | Technology used to detect multiple energies. Defined Terms: INTEGRATING physical detector integrates the full X-Ray spectrum. MULTILAYER physical detector layers absorb different parts of the X-Ray spectrum PHOTON_COUNTING physical detector counts photons with energy discrimination capability
>X-Ray Detector Label | (0018,9373) | 3 | Label of this item in the Multi-energy CT X-Ray Detector Sequence. ### Note The label might be High, Low or some nominal bin energy.
>Nominal Max Energy | (0018,9374) | 1C | Nominal maximum energy in keV of photons that are integrated/counted by the detector (see Section C.8.2.2.1.1). Due to energy resolution limits of the detector, some photons above the nominal maximum may be counted. Required if Multi-energy Detector Type (0018,9372) is PHOTON_COUNTING. May be present otherwise.
>Nominal Min Energy | (0018,9375) | 1C | Nominal minimum energy in keV of photons that are integrated/counted by the detector (see Section C.8.2.2.1.1). Due to energy resolution limits of the detector, some photons below the nominal minimum may be counted. Required if Multi-energy Detector Type (0018,9372) is PHOTON_COUNTING. May be present otherwise.
>Effective Bin Energy | (0018,936E) | 3 | Energy of the heterogeneous (polychromatic) photon beam represented by this detector (see Section C.8.2.2.1.1) calculated as if it were monochromatic. ### Note E.g., this can be calculated based on the beam spectrum or derived from the attenuation of phantom measurement.

###### C.8.2.2.2.1 Multi-energy X-Ray Detector Description

Each item in the Multi-energy CT X-Ray Detector Sequence (0018,936F) might describe either an integrating detector or one output corresponding to a specific spectrum of a physical detector like:

- One layer of a multi-layer detector.

- One energy bin of a photon counting detector.

- One energy threshold of a photon counting detector.

The sequence attribute descriptions will refer to a detector, meaning one item in the Multi-energy CT X-Ray Detector Sequence (0018,936F). The attributes use the phrase "physical detector" when it is necessary to refer to the actual device rather than the current item.

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DICOM PS3.3 2021b - Information Object Definitions