Материал: part17

Figure FFF.2.1-18. Attributes of the X-Ray Table Per Frame on Table Stepping​

FFF.2.1.4 Changes in X-Ray Controls​

FFF.2.1.4.1 Exposure Regulation Control​

This section provides information on the encoding of the "sensitive areas" used for regulation control of the X-Ray generation of an​ image that resulted from applying these X-Rays.​

FFF.2.1.4.1.1 User Scenario​

The user a) takes previous selected regulation settings or b) manually enters regulation settings or c) automatically gets computer-​ calculated regulation settings from requested procedures.​

Acquired images are networked or stored in offline media.​

Laterproblemsofimagequalityaredeterminedanduserwantstocheckforreasonsbyassessingthepositionsofthesensingregions.​

FFF.2.1.4.1.2 Encoding Outline​

TheEnhancedXAIODincludesamoduletosupplyinformationaboutactiveregulationcontrolsensingfields,theirshapeandposition​ relative to the pixel matrix.​

FFF.2.1.4.1.3 Encoding Details​

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

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Page 522​ DICOM PS3.17 2020a - Explanatory Information​

Table FFF.2.1-38. Enhanced XA Image Functional Group Macros​

FFF.2.1.4.1.3.1 X-Ray Exposure Control Sensing Regions Macro Recommendations​

This macro is recommended to encode details about sensing regions.​

If the position of the sensing regions is fixed during the multi-frame acquisition, the usage of this macro is shared.​

If the position of the sensing regions was changed during the multi-frame acquisition, this macro is encoded per-frame to reflect the​ individual positions.​

Thesamenumberofregionsistypicallyusedforalltheframesoftheimage.Howeveritistechnicallypossibletoactivateordeactivate​ some of the regions during a given range of frames, in which case this macro is encoded per-frame.​

Table FFF.2.1-39. X-Ray Exposure Control Sensing Regions Macro Recommendations​

In this section, two examples are given.​

The first example shows how three sensing regions are encoded: 1) central (circular), 2) left (rectangular) and 3) right (rectangular).​

1

250

2

511

774

Pixel Data Matrix

Figure FFF.2.1-19. Example of X-Ray Exposure Control Sensing Regions inside the Pixel Data matrix​

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The encoded values of the key Attributes of this example are shown in Figure FFF.2.1-20.​

Figure FFF.2.1-20. Attributes of the First Example of the X-Ray Exposure Control Sensing Regions​

The second example shows the same regions, but the field of view region encoded in the Pixel Data matrix has been shifted of 240​ pixels right and 310 pixels down, thus the left rectangular sensing region is outside the Pixel Data matrix as well as both rectangular​ regions overlap the top row of the image matrix.​

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2

201

464

Pixel Data Matrix

Figure FFF.2.1-21. Example of X-Ray Exposure Control Sensing Regions partially outside the Pixel Data​

matrix​

The encoded values of the key Attributes of this example are shown in Figure FFF.2.1-22.​

Figure FFF.2.1-22. Attributes of the Second Example of the X-Ray Exposure Control Sensing Regions​

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FFF.2.1.5 Image Detector and Field of View​

ThissectionprovidesinformationontheencodingoftheimagedetectorparametersandfieldofviewappliedduringtheX-Rayacquis-​ ition.​

FFF.2.1.5.1 User Scenario​

The user selects a given size of the field of view before starting the acquisition. This size can be smaller than the size of the Image​ Detector.​

The position of the field of view in the detector area changes during the acquisition in order to focus on an object of interest.​

Acquired image is networked or stored in offline media, then the image is:​

•​Displayed and reviewed in cine mode, and the field of view area needs to be displayed on the viewing screen;​

•​Used for quality assurance, to relate the pixels of the stored image to the detector elements, for instance to understand the image​ artifacts due to detector defects;​

•​Used to measure the dimension of organs or other objects of interest;​

•​Used to determine the position in the 3D space of the projection of the objects of interest.​

FFF.2.1.5.2 Encoding Outline​

The XA SOP Class does not encode some information to fully characterize the geometry of the conic projection acquisition, such as​ the position of the Positioner Isocenter on the FOV area. Indeed, the XA SOP Class assumes that the isocenter is projected in the​ middle of the FOV.​

TheEnhancedXASOPClassencodesthepositionoftheIsocenteronthedetector,aswellasspecificFOVAttributes(origin,rotation,​ flip) per-frame or shared. It encodes some existing Attributes from DX to specify information of the Digital Detector and FOV. It also​ allowsdifferentiatingtheimageintensifiervs.thedigitaldetectorandthendefinesconditionsonAttributesdependingonimageintens-​ ifier or digital detector.​

FFF.2.1.5.3 Encoding Details​

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

Table FFF.2.1-40. Enhanced X-Ray Angiographic Image IOD Modules​

Table FFF.2.1-41. Enhanced XA Image Functional Group Macros​

FFF.2.1.5.3.1 XA/XRF Acquisition Module Recommendations​

The usage of this module is recommended to specify the type and details of the receptor.​

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