Материал: part03

(padded) A-lines.​

Note​

Will be the same as Rows (0028,0010) for a FOR​

PROCESSING image.​

C.8.27.4 Intravascular OCT Processing Parameters Module​

Table C.8.27.4-1 describes the parameters used for processing an Intravascular Optical Coherence Tomography polar data image.​

Table C.8.27.4-1. Intravascular OCT Processing Parameters Module Attributes​

C.8.27.4.1 Refractive Index Applied​

For Refractive Index Applied (0052,003A) a value of YES indicates that Effective Refractive Index (0052,0004) correction has been​ appliedtothereportedA-linePixelSpacing(0052,0014)Attribute. Avalue of NOindicatesthat EffectiveRefractiveIndex(0052,0004)​ correction has not been applied (i.e., A-line Pixel Spacing corresponds to the pixel spacing in air).​

C.8.27.4.2 Pixel Intensity Relationship​

Pixel Intensity Relationship (0028,1040) shall identify the relationship of the pixel values to the IVOCT A-line intensity.​

Defined Terms:​

LIN​Approximately proportional to A-line intensity.​

LOG​Non-linear "Log Function"; A Pixel Intensity Relationship LUT shall be included with the image to allow it to be scaled back to​ its proportional A-line intensity value.​

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C.8.27.5 Intravascular Image Acquisition Parameters Module​

Table C.8.27.5-1 describes the parameters and characteristics of an intravascular image acquisition. These parameters are common​ to both IVUS and IVOCT.​

Table C.8.27.5-1. Intravascular Image Acquisition Parameters Module Attributes​

C.8.27.5.1 IVUS Acquisition​

The Attribute IVUS Acquisition (0018,3100) denotes the method used to acquire the Intravascular Images.​

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MOTORIZED: The Intravascular imaging catheter is positioned in the blood vessel proximal or distal to the anatomical structures to​ be examined. The catheter is attached to a motorized mechanism capable of either pushing forward or pulling back the catheter​ through the vessel at a constant velocity, as specified by the IVUS Pullback Rate (0018,3101). The motorized acquisition takes place​ during the time between acquisition of the IVUS Pullback Start Frame Number (0018,3103), and acquisition of the IVUS Pullback​ Stop Frame Number (0018,3104).​

MANUAL: The Intravascular imaging catheter is positioned in the blood vessel proximal or distal to the anatomical structures to be​ examined. The catheter is then manually pulled back or pushed forward through the vessel segment of interest.​

SELECTIVE: The Intravascular imaging catheter is positioned in the blood vessel. The catheter is then manually pushed forward​ and/or pulled back to examine the anatomical structures in the vessel.​

MEASURED: The Intravascular imaging catheter is positioned in the blood vessel near the anatomical structures to be examined.​ The catheter is then pulled back or pushed forward through the vessel segment of interest. The longitudinal movement between each​ acquired frame is measured and recorded. See Section C.8.27.6.2 for more information.​

C.8.27.5.2 IVUS Pullback Rate​

The Attribute IVUS Pullback Rate (0018,3101) specifies the constant velocity of longitudinal movement of the Intravascular imaging​ catheter. Positive values indicate movement from Distal to Proximal (pulling back). Negative values indicate movement from Proximal​ to Distal (pushing forward).​

C.8.27.6 Intravascular OCT Functional Group Macros​

The following sections contain Functional Group Macros specific to the Intravascular OCT IOD.​

C.8.27.6.1 Intravascular OCT Frame Type Macro​

Table C.8.27.6.1-1 specifies the Attributes of the Intravascular OCT Frame Type Functional Group.​

Table C.8.27.6.1-1. Intravascular OCT Frame Type Macro Attributes​

Enumerated Values and Defined Terms are the same as those for​ the four values of Image Type (0008,0008), except that the value​ MIXED is not allowed.​

See Section C.8.27.2.1.​

C.8.27.6.2 Intravascular Frame Content Macro​

Table C.8.27.6.2-1 specifies the Attributes of the Intravascular Frame Content Functional Group.​

Table C.8.27.6.2-1. Intravascular Frame Content Macro Attributes​

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See Section C.8.27.6.3.2 for further explanation.​

C.8.27.6.3.1 OCT Z Offset Correction​

OCT Z Offset Correction (0052,0030) specifies the number of pixels to shift the A-lines of the frame to correct for the path length dif-​ ference between the OCT Sample arm and Reference arm (in air). A positive value of Z Offset correction means pixels are shifted​ further away from the catheter optics. A negative value of Z Offset correction means pixels are shifted closer to the catheter optics.​ See Figure C.8.27-2​

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A

Before Correction

B

After Correction

Positive

Z-Offset

Correction

Figure C.8.27-2. OCT Z Offset Correction Example​

C.8.27.6.3.2 A-line Padding​

Padded A-lines shall not be used in FOR PRESENTATION frames. Padded A-lines shall only be encoded in the high order rows of​ the FOR PROCESSING frame and shall be contiguous. Padded A-lines may contain arbitrary pixel values.​

C.8.28 Ophthalmic Thickness Map Modules​

C.8.28.1 Ophthalmic Thickness Map Series Module​

Table C.8.28.1-1 specifies the Attributes that identify and describe general information about the Ophthalmic Thickness Map Series.​

Table C.8.28.1-1. Ophthalmic Thickness Map Series Module Attributes​

Only a single Item shall be included in this Sequence.​

Required if a Performed Procedure Step SOP Class was​ involved in the creation of this Series.​

>Include Table 10-11 “SOP Instance Reference Macro Attributes”​

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