Материал: part17

Figure FFF.2.1-27. Attributes of the Second Example of Field of View on Digital Detector​

In the third example, in addition to the binning factor of 2 between the detector matrix and the digital image, there is a resizing of 0.5​ (downsizing) between the digital image (binned) and the stored image.​

The encoded values of the key Attributes of this example are shown in Figure FFF.2.1-28.​

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Figure FFF.2.1-28. Attributes of the Third Example of Field of View on Digital Detector​

Note that the description of the field of view Attributes (dimension, origin) is the same in these three examples. The field of view​ definition is independent from the binning and resizing processes.​

FFF.2.1.6 Acquisitions With Contrast​

ThissectionprovidesinformationontheencodingofthepresenceandtypeofcontrastbolusadministeredduringtheX-Rayacquisition.​

FFF.2.1.6.1 User Scenario​

The user performs image acquisition with injection of contrast agent during the X-Ray acquisition. Some frames are acquired without​ contrast, some others with contrast.​

The type of contrast agent can be radio-opaque (e.g., iodine) or radio-transparent (e.g., CO2).​

The information of the type of contrast and its presence or absence in the frames can be used by post-processing applications to set​ up e.g., vessel detection or image quality algorithms automatically.​

FFF.2.1.6.2 Encoding Outline​

The Enhanced XA SOP Class encodes the characteristics of the contrast agent(s) used during the acquisition of the image, including​ the type of absorption (radio-opaque or radio-transparent).​

The Enhanced XA SOP Class also allows encoding the presence of contrast in a particular frame or set of frames, by encoding the​ Contrast/Bolus Usage per-frame.​

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FFF.2.1.6.3 Encoding Details​

This section provides detailed recommendations of the key Attributes to address this particular scenario.​

Table FFF.2.1-46. Enhanced X-Ray Angiographic Image IOD Modules​

Table FFF.2.1-47. Enhanced XA Image Functional Group Macros​

FFF.2.1.6.3.1 Enhanced Contrast/bolus Module Recommendations​

The usage of this module is recommended to specify the type and characteristics of the contrast agent administered.​

FFF.2.1.6.3.2 Contrast/bolus Usage Macro Recommendations​

The usage of this macro is recommended to specify the characteristics of the contrast per-frame.​

Table FFF.2.1-48. Contrast/Bolus Usage Macro Recommendations​

Note that it is not expected to be YES if Contrast/Bolus Agent​

Administered (0018,9342) equals NO.​

FFF.2.1.6.4 Example​

In this example, the user starts the X-Ray acquisition at 4 frames per second at 3:35pm. After one second the user starts the injection​ of 45 milliliters of contrast media Iodipamide (350 mg/ml Cholographin (Bracco) ) at a flow rate of 15 ml/sec during three seconds, in​ intra-arterial route. When the injection of contrast agent is finished, the user continues the X-Ray acquisition for two seconds until​ wash out of the contrast agent.​

There could be two ways to determine the presence of contrast agent on the frames:​

•​The injector is connected to the X-Ray acquisition system, the presence of contrast agent is determined based on the injector​ start/stop signals and a preconfigured delay to allow the contrast to reach the artery of interest, or.​

•​The X-Ray system processes the images in real time and detects the presence or absence of contrast agent on the images.​

In this example, the image acquired contains 25 frames: From frames 5 to 17, the contrast is being injected. From frames 8 to 23,​ the contrast is visible on the pixel data.​

The figure below shows the Attributes of this example in a graphical representation of the multi-frame acquisition.​

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Contrast/bolus intensity visible on the pixel data

Acquisition DateTime (0008,002A)

Contrast/Bolus Start Time (0018,1042)

Contrast/Bolus Stop Time (0018,1043)

Injection of contrast agent

Injection of contrast agent

Contrast Flow Duration (0018,1047)

Contrast agent visible on the pixels

Contrast agent visible on the pixels

Figure FFF.2.1-29. Example of contrast agent injection​

The encoded values of the key Attributes of this example are shown in Figure FFF.2.1-30.​

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Figure FFF.2.1-30. Attributes of Contrast Agent Injection​

FFF.2.1.7 Acquisition Parameters For X-Ray Generation (kVp, mA, …)​

This section provides information on the encoding of the parameters related to the X-Ray generation.​

FFF.2.1.7.1 User Scenario​

The user performs X-Ray acquisitions during the examination. Some of them are dynamic acquisitions where the positioner and/or​ the table have moved between frames of the Multi-frame Image, the acquisition parameters such as kVp, mA and pulse width may​ change per-frame to be adapted to the different anatomy characteristics.​

Later quality assurance wants to assess the X-Ray generation techniques in order to understand possible degradation of image​ quality, or to estimate the level of irradiation at different skin areas and body parts examined.​

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