C.8.7 X-Ray Modules

This Section describes Modules used in one or more X-Ray IODs. These Modules contain Attributes that are specific to X-Ray images.

C.8.7.1 X-Ray Image Module

Table C.8-26X-RAY IMAGE MODULE ATTRIBUTES

Attribute Name Tag Type Attribute Description
Frame Increment Pointer (0028,0009) 1C Required if Multi-Frame Image. Contains the Data Element Tag of the attribute that is used as the Frame increment in Multi-frame image pixel data (See C.7.6.6). Specialized for X-Ray as Enumerated Value: 00181063H = Frame Time (0018,1063); 00181065H = Frame Time Vector (0018,1065).
Lossy Image Compression (0028,2110) 1C Specifies whether an Image has undergone lossy compression. Enumerated Values: 00 = Image has NOT been subjected to lossy compression. 01 = Image has been subjected to lossy compression. See C.7.6.1.1.5 Required if Lossy Compression has been performed on the Image.
Image Type (0008,0008) 1 Image identification characteristics. See C.8.7.1.1.1 for specialization.
Pixel Intensity Relationship (0028,1040) 1 The relationship between the Pixel sample values and the X-Ray beam intensity. See Section C.8.7.1.1.2.
Samples per Pixel (0028,0002) 1 Number of samples (color planes) in this image shall have a value of 1.
Photometric Interpretation (0028,0004) 1 Specifies the intended interpretation of the pixel data. Only MONOCHROME2 may be used.
Bits Allocated (0028,0100) 1 Number of bits allocated for each pixel sample. See Section C.8.7.1.1.6.
Bits Stored (0028,0101) 1 Number of bits stored for each pixel sample. See Section C.8.7.1.1.7.
High Bit (0028,0102) 1 Most significant bit for pixel sample data. See Section C.8.7.1.1.8.
Pixel Representation (0028,0103) 1 Data representation of the pixel samples. Shall have the value: 0000H = Unsigned Integer.
Scan Options (0018,0022) 3 Parameters of scanning sequence. See Section C. 8.7.1.1.4.
Include 'General Anatomy Optional Macro' Table 10-7 No Context ID for the Anatomic Region Sequence is defined.
R Wave Pointer (0028,6040) 3 Marks the location(s) of the R Wave in the cardiac cycles by referencing frame numbers; frame numbers begin with 1.
Referenced Image Sequence (0008,1140) 1C Other images significantly related to this image. Shall be present if Image Type (0008,0008) Value 3 is BIPLANE A or BIPLANE B. May be present otherwise. One or more items shall be included in this sequence. See Section C.8.7.1.1.13.
>Include ‘Image SOP Instance Reference Macro’ Table 10-3
>Purpose of Reference Code Sequence (0040,A170) 3 Describes the purpose for which the reference is made. Only a single Item is permitted in this Sequence.
>>Include Code Sequence Macro Table 8.8-1 Defined Context ID 7201
Derivation Description (0008,2111) 3 A text description of how this image was derived. See C.8.7.1.1.5 for further explanation.
Acquisition Device Processing Description (0018,1400) 3 Indicates any visual processing performed on the images prior to exchange. See Section C.8.7.1.1.3.
Frame Label Vector (0018,2002) 3 A multi-valued attribute that contains a descriptive label for each of the image frames. The number of values shall equal the number of frames.
Frame Dimension Pointer (0028,000A) 3 Contains the Data Element Tags of one or more attributes that vary or increment for the frames of a multi-frame image. See C.8.7.1.1.12. Shall not be present if it would contain only one value and that value would be Frame Time (0018,1063) or Frame Time Vector (0018,1065).
Calibration Image (0050,0004) 3 Indicates whether a reference object (phantom) of known size is present in the image and was used for calibration. Enumerated Values: YES NO Device is identified using the Device module. See C.7.6.12.

C.8.7.1.1 X-Ray Image Attribute Descriptions

C.8.7.1.1.1 Image Type

The Image Type attribute identifies important image characteristics in a multiple valued data element. For X-Ray, Image Type is specialized as follows:

a. Value 1 shall identify the Pixel Data Characteristics in accordance with Section C.7.6.1.1.2; Enumerated Values are: ORIGINAL and DERIVED;

b. Value 2 shall identify the Patient Examination Characteristics in accordance with Section C.7.6.1.1.2; Enumerated Values are: PRIMARY and SECONDARY.

Note: X-Ray images generally use PRIMARY value for images captured from patient exposure.

c. Value 3 shall identify the image set in terms of the imaging planes. Enumerated Values are:

SINGLE PLANE Image is a single plane acquisition;
BIPLANE A Image is the first plane (e.g., Frontal) of a Bi-plane acquisition;
BIPLANE B Image is the second plane (e.g., Lateral) of a Bi-plane acquisition

d. Other Values are implementation specific (optional).

C.8.7.1.1.2 Pixel Intensity Relationship

Pixel Intensity Relationship (0028,1040) shall identify the relationship of the pixel values to the X-Ray beam intensity. Defined terms are:

LIN Approximately proportional to X-Ray beam intensity;
LOG Non-linear “ Log Function”; A Modality LUT shall be included with the image to allow it to be scaled back to its proportional value to X-Ray beam intensity;
DISP Ready to be displayed; A Modality LUT may be included with the image to allow it to be scaled back to its proportional value to X-Ray beam intensity. The Attribute Acquisition Device Processing Description may be used to provide some indication on the pre-processing performed to create the ready to be displayed image.

C.8.7.1.1.3 Acquisition Device Processing Description

Acquisition Device Processing Description (0018,1400) provides some indication in human readable text of the digital processing on the images before exchange. Examples of this processing are: edge enhanced, subtracted, time filtered, gamma corrected, convolved (spatially filtered).

C.8.7.1.1.4 Scan Options

The Scan Options attribute identifies any acquisition technique which was used during the acquisition of the image. Defined Terms are:

EKG EKG Event Trigger
PHY Physiological Event Trigger
TOMO Tomography
CHASE Bolus Chasing
STEP Stepping
ROTA Rotation

C.8.7.1.1.5 Derivation Description

If an Image is identified to be a Derived image (see C.8.7.1.1.1 Image Type), Derivation Description (0008,2111) is an optional and implementation specific text description of the way the image was derived from an original image. As applied to X-Ray images, it may be used to describe derivation operations such as edge enhancement, temporal filtering, digital subtraction, or other linear and non-linear transformations.

C.8.7.1.1.6 Bits Allocated

For X-Ray Images, Bits Allocated (0028,0100) shall have the Enumerated Value of 8 or 16.

C.8.7.1.1.7 Bits Stored

For X-Ray Images, Bits Stored (0028,0101) shall have the Enumerated Values of 8, 10, 12, or 16.

C.8.7.1.1.8 High Bit

For X-Ray Images, High Bit (0028,0102) shall have the Enumerated Value of one less than the value in Bit Stored.

C.8.7.1.1.9 Synchronization of Frame and Waveform Times

The synchronization of a multiframe X-Ray image with a waveform (e.g., ECG, pressure, or respiration) encoded in a different SOP Instance is managed through the attributes of the Synchronization Module (see Section C.7.4.2) of the Frame of Reference IE.

Note: The use of a Curve IE within the X-Ray IODs was previously defined in DICOM (see PS3.3-2004). That use has been retired in favor of encoding waveform data in a separate IOD.

C.8.7.1.1.12 Frame Dimension Pointer

Frame Dimension Pointer (0028,000A) identifies attributes that vary or increment with each frame, and which are clinically significant for viewing or processing the image. This is intended for SOP Instances whose preferred clinical presentation is dependent on frame relationships other than simply time.

Defined Terms for multiframe cine from the Cine Module (see C.7.6.5) are:

00181063H = Frame Time (0018,1063)00181065H = Frame Time Vector (0018,1065)

Defined Terms for rotational acquisition from the XA Positioner Module (see C.8.7.5) are:

00181520H = Positioner Primary Angle Increment (0018,1520)00181521H = Positioner Secondary Angle Increment (0018,1521)

Defined Terms for stepped acquisition from the X-Ray Table Module (see C.8.7.4) are:

00181135H = Table Vertical Increment (0018,1135)00181137H = Table Longitudinal Increment (0018,1137)00181136H = Table Lateral Increment (0018,1136)

Defined Terms for an arbitrary labeled increment:

00182002H = Frame Label Vector (0018,2002)

Notes: 1. Previous editions of the standard did not include the optional Frame Dimension Pointer (0028,000A), but instead depended entirely on the mandatory Frame Increment Pointer (0028,0009), and envisaged that only time and no other dimension would relate frames. Image creators that add the Frame Dimension Pointer (0028,000A) must anticipate that many implementations will ignore or discard this attribute when displaying or storing images and continue to assume that frames are temporally related.

2. Frame Time (0018,1063) or Frame Time Vector (0018,1065) will also be present and will contain appropriate values consistent with the times of acquisition of the frames.

C.8.7.1.1.13 Referenced Image Sequence

When Image Type (0008,0008) Value 3 is BIPLANE A or BIPLANE B, Referenced Image Sequence (0008,1140) shall be used to identify the corresponding SOP Instance of the Biplane acquisition. In this case, either:

The Referenced Frame Number (0008,1160) attribute shall not be present in the Item that references the corresponding SOP Instance of the Biplane acquisition.

C.8.7.2 X-Ray Acquisition Module

Table C.8-27X-RAY ACQUISITION MODULE ATTRIBUTES

Attribute Name Tag Type Attribute Description
KVP (0018,0060) 2 Peak kilo voltage output of the X-Ray generator used.
Radiation Setting (0018,1155) 1 Identify the general level of X-Ray dose exposure. Enumerated values are: SC = low dose exposure generally corresponding to fluoroscopic settings (e.g. preparation for diagnostic quality image acquisition); GR = high dose for diagnostic quality image acquisition (also called digital spot or cine);
X-Ray Tube Current (0018,1151) 2C X-Ray Tube Current in mA. Required if Exposure (0018,1152) is not present. May be present otherwise.
X-Ray Tube Current in µA (0018,8151) 3 X-Ray Tube Current in µA.
Exposure Time (0018,1150) 2C Duration of X-Ray exposure in msec. See 8.7.2.1.1. Required if Exposure (0018,1152) is not present. May be present otherwise.
Exposure Time in µS (0018,8150) 3 Duration of X-Ray exposure in µsec.
Exposure (0018,1152) 2C The exposure expressed in mAs, for example calculated from Exposure Time and X-Ray Tube Current. Required if either Exposure Time (0018,1150) or X-Ray Tube Current (0018,1151) are not present. May be present otherwise.
Exposure in μAs (0018,1153) 3 The exposure expressed in μAs, for example calculated from Exposure Time and X-Ray Tube Current.
Grid (0018,1166) 3 Identify the grid. Only a single value shall be present. Defined Terms are: IN = A Grid is positioned; NONE = No Grid is used.
Average Pulse Width (0018,1154) 3 Average width of X-Ray pulse in msec.
Radiation Mode (0018,115A) 3 Specifies X-Ray radiation mode. Defined Terms: CONTINUOUS PULSED
Type of Filters (0018,1161) 3 Type of filter(s) inserted into the X-Ray beam (e.g. wedges).
Intensifier Size (0018,1162) 3 Diameter of X-Ray intensifier in mm
Field of View Shape (0018,1147) 3 Shape of the Image Intensifier Field of View. See C.8.7.2.1.2. Defined Terms are: ROUND RECTANGLE
Field of View Dimension(s) (0018,1149) 3 Dimensions of the Image Intensifier Field of View in mm. If Rectangle, row dimension followed by column; if Round, diameter.
Imager Pixel Spacing (0018,1164) 3 Physical distance measured at the front plane of the Image Receptor housing between the center of each pixel specified by a numeric pair - row spacing value(delimiter) column spacing value in mm. See 10.7.1.3 for further explanation of the value order. The value of this attribute shall never be adjusted to account for correction for the effect of geometric magnification or calibration against an object of known size; Pixel Spacing (0028,0030) is specified for that purpose.
Include Basic Pixel Spacing Calibration Macro (Table 10-10)
Focal Spot (0018,1190) 3 Nominal focal spot size in mm used to acquire this image.
Image and Fluoroscopy Area Dose Product (0018,115E) 3 X-Ray dose, measured in dGy*cm*cm, to which the patient was exposed for the acquisition of this image plus any non-digitally recorded fluoroscopy which may have been performed to prepare for the acquisition of this image. Note: The sum of the area dose product of all images of a Series or a Study may not result in the total area dose product to which the patient was exposed.

C.8.7.2.1 X-Ray Acquisition Attribute Descriptions

C.8.7.2.1.1 Exposure Time

Exposure time is the cumulative time the patient received X-Ray exposure during this image (Multi-frame image acquisition). Calculation is pulse width * number of frames.

C.8.7.2.1.2 Field of View

The Field of View Attribute describes the shape and dimensions of the Image Receptor Field of View , applicable to both Image Intensifier and Digital Detector. This could be further restricted by the Collimator. See Section C.8.7.3.

C.8.7.3 X-Ray Collimator

An X-Ray Collimator is a device placed close to the X-Ray Source to restrict the span of the X-Ray beam. It is often made of lead shutters. Figure C.8-9 presents in a graphical form its relationship with the Field Of View Dimensions (0018,1149).

Geometry of the collimator is specified with respect to a row and column coordinate system where the origin is the upper left hand pixel. This origin is specified by the values 1,1 for row/column. A row coordinate represent a number of raw spacing (vertical) and a column coordinate represents a column spacing (horizontal). Up to three different collimator shapes may be used and superimposed.

[pic]

Figure C.8-9Relationships of X-Ray Collimator

Table C.8-28 X-RAY COLLIMATOR MODULE ATTRIBUTES

Attribute Name Tag Type Attribute Description
Collimator Shape (0018,1700) 1 Shape(s) of the collimator. Enumerated Values: RECTANGULAR CIRCULAR POLYGONAL This multi-valued Attribute shall contain at most one of each Enumerated Value.
Include ‘X-Ray Collimator Dimensions Macro’ Table C.8-28b

Table C.8-28bX-RAY COLLIMATOR DIMENSIONS MACRO ATTRIBUTES

Attribute Name Tag Type Attribute Description
Collimator Left Vertical Edge (0018,1702) 1C Required if a value of Collimator Shape (0018,1700) is RECTANGULAR. Location of the left edge of the rectangular collimator with respect to pixels in the image given as column. See C.8.7.3.1.1.
Collimator Right Vertical Edge (0018,1704) 1C Required if a value of Collimator Shape (0018,1700) is RECTANGULAR. Location of the right edge of the rectangular collimator with respect to pixels in the image given as column. See C.8.7.3.1.1.
Collimator Upper Horizontal Edge (0018,1706) 1C Required if a value of Collimator Shape (0018,1700) is RECTANGULAR. Location of the upper edge of the rectangular collimator with respect to pixels in the image given as row. See C.8.7.3.1.1.
Collimator Lower Horizontal Edge (0018,1708) 1C Required if a value of Collimator Shape (0018,1700) is RECTANGULAR. Location of the lower edge of the rectangular collimator with respect to pixels in the image given as row. See C.8.7.3.1.1.
Center of Circular Collimator (0018,1710) 1C Required if a value of Collimator Shape (0018,1700) is CIRCULAR. Location of the center of the circular collimator with respect to pixels in the image given as row and column. See C.8.7.3.1.1.
Radius of Circular Collimator (0018,1712) 1C Required if a value of Collimator Shape (0018,1700) is CIRCULAR. Radius of the circular collimator with respect to pixels in the image given as a number of pixels along the row direction. See C.8.7.3.1.1.
Vertices of the Polygonal Collimator (0018,1720) 1C Required if a value of Collimator Shape (0018,1700) is POLYGONAL. Multiple Values where the first set of two values are: row of the origin vertex; column of the origin vertex. Two or more pairs of values follow and are the row and column coordinates of the other vertices of the polygon collimator. Polygon collimators are implicitly closed from the last vertex to the origin vertex and all edges shall be non-intersecting except at the vertices.

C.8.7.3.1 X-Ray Collimator Attribute Descriptions

C.8.7.3.1.1 Collimator Vertical and Horizontal Edges

These attributes specify the pixel row or column where the X-Ray beam is fully obscured by a rectangular collimator:

- if the left edge of the collimator is not visible, Collimator Left Vertical Edge (0018,1702) shall have a value of 0;

- if the right edge of the collimator is not visible, Collimator Right Vertical Edge (0018,1704) value shall be 1 greater than the value of the Columns (0028,0011) attribute;

- if the top edge of the collimator is not visible, Collimator Upper Horizontal Edge (0018,1706) shall have a value of 0;

- if the bottom edge of the collimator is not visible, Collimator Lower Horizontal Edge (0018,1708) value shall be 1 greater than the value of the Rows (0028,0010) attribute.

C.8.7.4 X-Ray Table Module

Table C.8-29 contains Attributes that describe X-Ray images acquired with movement of the patient imaging table.

Table C.8-29X-RAY TABLE MODULE ATTRIBUTES

Attribute Name Tag Type Attribute Description
Table Motion (0018,1134) 2 Defined terms: STATIC DYNAMIC
Table Vertical Increment (0018,1135) 2C Incremental change in Vertical position of the table relative to first frame of Multi-frame image given in mm. Required if Table Motion is DYNAMIC.
Table Longitudinal Increment (0018,1137) 2C Incremental change in Longitudinal position of the table relative to first frame of Multi-frame image in mm. Table motion towards +90°position of the primary angle of the positioner is positive. See C.8.7.4.1.2. Required if Table Motion is DYNAMIC.
Table Lateral Increment (0018,1136) 2C Incremental change in Lateral position of the table relative to first frame of Multi-frame image given in mm. Table motion towards +90°position of the secondary angle of the positioner is positive. See C.8.7.4.1.3. Required if Table Motion is DYNAMIC.
Table Angle (0018,1138) 3 Angle of table plane in degrees relative to horizontal plane [Gravity plane]. Positive values indicate that the head of the table is upwards.

C.8.7.4.1 X-Ray Table Attribute Descriptions

C.8.7.4.1.1 Table Motion Increments

This section is replaced by section C.8.7.4.1.4

C.8.7.4.1.2 Table Longitudinal Increment

The direction of the longitudinal movement is perpendicular to the primary axis of rotation of the positioner. A positive value of Table Longitudinal Increment (0018,1137) attributes indicates a movement towards the +90° position of the positioner, see figure C.8-9a.

[pic]

Figure C.8-9aTable Longitudinal Movement

C.8.7.4.1.3 Table Lateral Increment

The direction of the lateral movement is perpendicular to the secondary axis of rotation of the positioner. A positive value of Table Lateral Increment (0018,1136) attributes indicates a movement towards the +90° position of the positioner, see figure C.8-9b.

[pic]

Figure C.8-9b Table Lateral Movement

Note: The terms “longitudinal” and “lateral” are relative to an operator standing tableside, and facing the patient. Thus lateral movement is to the left and right of the operator, and longitudinal movement is towards or away from the operator.

C.8.7.4.1.4 Table Motion with Patient in relation to Imaging Chain

The table moves the Patient with respect to the imaging chain. This is being tracked as a motion of the imaging chain with respect to a coordinate system (X, Y, Z) attached to the patient (assumption is that the patient does not move with respect to the table). The coordinate system origin is fixed with respect to the patient at the time of the first frame. The X-axis is increasing to the left hand side of the patient. The Y-axis is increasing to the posterior side of the patient. The Z-axis is increasing toward the head of the patient (see Section C.7.6.2.1.1). The Patient Plane is then defined by the X and Z-axes as drawn in Figure C.8-10).

Notes: 1. Table motion causes the apparent locus of imaging to move in the opposite direction. For instance, with the patient supine and the table motion towards +90°of the primary axis of rotation of the positioner, the area of the patient imaged moves toward the right hand side of the patient.

2. When the patient is positioned prone or supine ( Figure C.8-2 showing the supine position) the Table Longitudinal Increment (0018,1137) table motion takes place along the patient X-axis and the Table Lateral Increment (0018,0036) along the Z-axis. For patient positioned left or right decubitus, the Table Longitudinal Increment takes place along the Y-axis, the other direction is not changed.

[pic]

Figure C.8-10 Table Motion Vector Coordinates

C.8.7.5 XA Positioner Module

Table C.8-30 contains IOD Attributes that describe a c-arm positioner typically used in acquiring X-Ray Angiographic Images. The coordinate system used to track the positioner is defined in reference to the patient. The definition of coordinates with respect to the equipment is not supported. Furthermore, this module does not describe the movement of the Patient.

Note: The scope of the XA IOD is to address images produced on acquisition equipment equipped with an X-Ray source and an image Receptor positioned by what is general called a c-arm For clinical areas other than Angiography which are using a c-arm to position the X-Ray source and image receptor (e.g. Interventional Procedures and Myelography and Biopsy/Localization), the X-Ray Angiography Image Object should be also used. Although the object is optimized for c-arm systems, it may also be used by other systems which support a similar coordinate system, such as some RF systems.

Table C.8-30XA POSITIONER MODULE ATTRIBUTES

Attribute Name Tag Type Attribute Description
Distance Source to Patient (0018,1111) 3 Distance in mm from source to isocenter (center of field of view). Note: This value is traditionally referred to as Source Object Distance (SOD).
Distance Source to Detector (0018,1110) 3 Distance in mm from source to detector center. Note: This value is traditionally referred to as Source Image Receptor Distance (SID).
Estimated Radiographic Magnification Factor (0018,1114) 3 Ratio of Source Image Receptor Distance (SID) over Source Object Distance (SOD).
Positioner Motion (0018,1500) 2C Used to describe the activity of the imaging devices. Defined terms: DYNAMIC, STATIC. See C.8.7.5.1.1. Required if the Pixel Data (7FE0,0010) contains more than one frame. May be present otherwise.
Positioner Primary Angle (0018,1510) 2 Position of the X-Ray Image Intensifier about the patient from the RAO to LAO direction where movement from RAO to vertical is positive. See C.8.7.5.1.2.
Positioner Secondary Angle (0018,1511) 2 Position of the X-Ray Image Intensifier about the patient from the CAU to CRA direction where movement from CAU to vertical is positive. See C.8.7.5.1.2
Positioner Primary Angle Increment (0018,1520) 2C Incremental change in primary positioner angle for each frame. See C.8.7.5.1.3. Required if Positioner Motion (0018,1500) equals DYNAMIC.
Positioner Secondary Angle Increment (0018,1521) 2C Incremental change in secondary positioner angle for each frame. See C.8.7.5.1.3. Required if Positioner Motion (0018,1500) equals DYNAMIC.
Detector Primary Angle (0018,1530) 3 Angle of the X-Ray beam in the row direction in degrees relative to the normal to the detector plane. Positive values indicate that the X-Ray beam is tilted towards higher numbered columns. Negative values indicate that the X-Ray beam is tilted towards lower numbered columns. See C.8.7.5.1.4.
Detector Secondary Angle (0018,1531) 3 Angle of the X-Ray beam in the column direction in degrees relative to the normal to the detector plane. Positive values indicate that the X-Ray beam is tilted towards lower numbered rows. Negative values indicate that the X-Ray beam is tilted towards higher numbered rows. See C.8.7.5.1.4.

C.8.7.5.1 XA Positioner Attribute Descriptions

C.8.7.5.1.1 Positioner Motion

Positioner Motion (0018,1500) attribute is STATIC if the imaging table moves during a multi-frame acquisition, but the X-Ray positioner do not move.

If Pixel Data (7FE0,0010) contains a single frame and a value of the Positioner Motion (0018,1500) attribute is provided, the value shall be STATIC.

Note: If the positioner undergoes translation (non-rotational movement) during the acquisition, then that motion shall be described by an opposite table motion (See Section C.8.7.4).

C.8.7.5.1.2 Positioner Primary and Secondary Angles

The definitions of Positioner Angles shall be with respect to the patient as illustrated in Figures C.8-11 and C.8-12 Zero degree is referenced to the origin perpendicular to the patient's chest. The Positioner Primary Angle definition is like longitude (in the equatorial plan); the Positioner Secondary Angle definition is like latitude (in the sagittal plane). The Positioner Angle attributes apply to the first frame of a multi-frame image. The valid range of Primary Positioner Angle is -180 to +180 degrees and the Secondary Positioner Angle range is -90 to + 90 degrees.

The Patient Plane is defined by the isocenter of the imaging device and slices through the patient such that it is perpendicular to the sagittal plane of the body. The Primary Axis of rotation is defined at the intersection of the Patient Plane and of the Sagittal Plane. The Positioner Primary Angle is defined in the transaxial plane at the isocenter with zero degrees in the direction perpendicular to the patient's chest and + 90 degrees at the Patient left hand side (LAO) and -90 at the Patient right hand side (RAO). The valid range of Primary Positioner Angle is -180 to +180 degrees.

The Secondary Axis is in the Patient Plane and is perpendicular to the Primary Axis at the isocenter. The Positioner Secondary Angle is defined in the Sagittal Plane at the isocenter with zero degrees in the direction perpendicular to the patient's chest. +90 degrees corresponds to the cranial direction. The Secondary Positioner Angle range is -90 to + 90 degrees.

At a 0 angle for both the Primary Angle (0018,1510) and Secondary Angle (0018,1511), the patient faces the Image Intensifier.

The Positioner Primary Angle (0018,1510) and Secondary Angle (0018,1511) apply to the first frame of a multi-frame image.

[pic]

Figure C.8-11Positioner Primary Angle

[pic]

Figure C.8-12 Positioner Secondary Angle

C.8.7.5.1.3 Positioner Angle Increments

If the positioner angles change during acquisition of a multi-frame image, the Positioner Angle Increment attributes describe the angular change per frame.

If the change in positioner angle is nominally constant for each frame, these fields may contain a single value of the average angular change per frame. Alternatively, the fields may contain a vector of offsets from the (initial) Positioner Angle attributes, with one value for each frame in the multi-frame image. The number of values in the Positioner Angle Increment attributes must be one, or must be equal to the Number of Frames attribute (0028,0008) in the Multi-Frame Module (see Section C.7.6.6).

Note: It is permissible to generate a vector of the absolute positioner angles in the Positioner Angle Increment attributes, and set the Positioner Primary and Secondary Angle attributes to value 0.

C.8.7.5.1.4 Detector Primary and Secondary Angles

Detector Angles are defined in a fashion similar to the positioner angles, except that the angle of the central x-ray beam vector is relative to the detector plane rather than the patient plane. The central x-ray beam vector is defined as the vector from the x-ray source through the isocenter to the detector plane. Zero degree is referenced to the normal to the detector plane pointing away from the x-ray source. The Detector Angle attributes apply to the first frame of a multi-frame image. The valid range of the Detector Angles is -90 to + 90 degrees.

The Primary Axis of rotation is defined along the line in the column direction of the detector plane which intersects the central x-ray beam vector. The Detector Primary Angle is defined in the plane perpendicular to the Primary Axis of rotation at the point where the central x-ray beam vector intersects the detector plane, with zero degrees in the direction normal to the detector plane and -90 degrees at the left hand side of the image (i.e., toward column 1) and +90 at the right hand side of the image (i.e., toward the highest numbered column). The valid range of Primary Detector Angle is -90 to +90 degrees.

The Secondary Axis is in the detector plane and is perpendicular to the Primary Axis at the intersection of the beam vector with the detector plane (i.e., it is along the row direction). The Detector Secondary Angle is defined in the plane perpendicular to the Secondary Axis at the point where the central x-ray beam vector intersects the detector plane, with zero degrees in the direction normal to the detector plane. +90 degrees corresponds to the direction toward the top of the image. The Secondary Detector Angle range is -90 to + 90 degrees.

C.8.7.6 XRF Positioner Module

Table C.8-31XRF POSITIONER MODULE ATTRIBUTES

Attribute Name Tag Type Attribute Description
Distance Source to Detector (0018,1110) 3 Distance in mm from source to detector center. Note: This value is traditionally referred to as Source Image Receptor Distance (SID).
Distance Source to Patient (0018,1111) 3 Distance in mm from source to isocenter (center of field of view). Note: This value is traditionally referred to as Source Object Distance (SOD).
Estimated Radiographic Magnification Factor (0018,1114) 3 Ratio of SID (Source Image Receptor Distance) over SOD (Source Object Distance).
Column Angulation (0018,1450) 3 Angle of the X-Ray beam in degree relative to an orthogonal axis to the detector plane. Positive values indicate that the tilt is towards the head of the table. Note: The detector plane is assumed to be parallel to the table plane.

C.8.7.7 X-Ray Tomography Acquisition Module

This Module describes the attributes of a Tomography acquisition (translation of X-Ray source during the acquisition of a single frame image).

Table C.8-32X-RAY TOMOGRAPHY ACQUISITION MODULE ATTRIBUTES

Attribute Name Tag Type Attribute Description
Tomo Layer Height (0018,1460) 1 Distance in mm between the table surface and the sharp image plane.
Tomo Angle (0018,1470) 3 Angle span in degrees of rotation of X-Ray Source during X-Ray acquisition.
Tomo Time (0018,1480) 3 Time in seconds the source has taken to rotate the Tomo Angle during X-Ray acquisition.
Tomo Type (0018,1490) 3 Type of tomography. Defined Terms: LINEAR SPIRAL POLYCYCLOIDAL CIRCULAR
Tomo Class (0018,1491) 3 Form of tomography: Defined Terms: MOTION TOMOSYNTHESIS
Number of Tomosynthesis Source Images (0018,1495) 3 The number of source images used to construct this tomosynthetic image. Only meaningful if Tomo Class (0018,1491) is TOMOSYNTHESIS. These may be listed in Source Image Sequence (0008,2112) of the General Image Module.

C.8.7.8 X-Ray Acquisition Dose Module

This Module describes the attributes related to dose delivery from an X-Ray source during the acquisition of an X-Ray image.

Table C.8-33X-RAY ACQUISITION DOSE MODULE ATTRIBUTES

Attribute Name Tag Type Attribute Description
KVP (0018,0060) 3 Peak kilo voltage output of the X-Ray generator used.
X-Ray Tube Current (0018,1151) 3 X-Ray Tube Current in mA.
X-Ray Tube Current in µA (0018,8151) 3 X-Ray Tube Current in µA.
Exposure Time (0018,1150) 3 Duration of X-Ray exposure in msec.
Exposure Time in µS (0018,8150) 3 Duration of X-Ray exposure in µsec.
Exposure (0018,1152) 3 The exposure expressed in mAs, for example calculated from Exposure Time and X-Ray Tube Current.
Exposure in µAs (0018,1153) 3 The exposure expressed in µAs, for example calculated from Exposure Time and X-Ray Tube Current.
Distance Source to Detector (0018,1110) 3 Distance in mm from source to detector center. Note: This value is traditionally referred to as Source Image Receptor Distance (SID).
Distance Source to Patient (0018,1111) 3 Distance in mm from source to the table, support or bucky side that is closest to the Imaging Subject, as measured along the central ray of the X-Ray beam. Note: 1. This definition is less useful in terms of estimating geometric magnification than a measurement to a defined point within the Imaging Subject, but accounts for what is realistically measurable in an automated fashion in a clinical setting. 2. This measurement does not take into account any air gap between the Imaging Subject and the “front” of the table or bucky. 3. If the detector is not mounted in a table or bucky, then the actual position relative to the patient is implementation or operator defined. 4. This value is traditionally referred to as Source Object Distance (SOD).
Image and Fluoroscopy Area Dose Product (0018,115E) 3 X-Ray dose, measured in dGy*cm*cm, to which the patient was exposed for the acquisition of this image plus any non-digitally recorded fluoroscopy which may have been performed to prepare for the acquisition of this image. Notes: 1. The sum of the area dose product of all images of a Series or a Study may not result in the total area dose product to which the patient was exposed. 2. This may be an estimated value based on assumptions about the patient’s body size and habitus.
Body Part Thickness (0018,11A0) 3 The average thickness in mm of the body part examined when compressed, if compression has been applied during exposure.
Relative X-Ray Exposure (0018,1405) 3 Indication of the applied dose, in manufacturer specific units. Notes: 1. This value is intended to provide a single location where manufacturer specific information can be found for annotation on a display or film, that has meaning to a knowledgeable observer. 2. This may be a calculated or measured value. Examples are the detector entrance dose (KB), the CR sensitivity value (S), or the logarithmic median (lgM). 3. DICOM specifies standard Attributes in Table 10-23 ‘Exposure Index Macro’ which are recommended.
Entrance Dose (0040,0302) 3 Average entrance dose value measured in dGy at the surface of the patient during the acquisition of this image. Note: This may be an estimated value based on assumptions about the patient’s body size and habitus.
Entrance Dose in mGy (0040,8302) 3 Average entrance dose value measured in mGy at the surface of the patient during the acquisition of this image. Note: This may be an estimated value based on assumptions about the patient’s body size and habitus.
Exposed Area (0040,0303) 3 Typical dimension of the exposed area at the detector plane. If Rectangular: row dimension followed by column; if Round: diameter. Measured in cm. Notes: 1. The exposed area should be consistent with values specified in the X-Ray Collimator Module, if present. 2. This may be an estimated value based on assumptions about the patient’s body size and habitus. 3. This attribute is used in the Radiation Dose Module with units in mm (see Section C.4.16 Table C.4-16).
Distance Source to Entrance (0040,0306) 3 Distance in mm from the source to the surface of the patient closest to the source during the acquisition of this image. Note: This may be an estimated value based on assumptions about the patient’s body size and habitus.
Comments on Radiation Dose (0040,0310) 3 User-defined comments on any special conditions related to radiation dose encountered during the acquisition of this image.
X-Ray Output (0040,0312) 3 The X-Ray output at the patient entrance surface and kVp used to acquire the image, measured in mGy/mAs. Note: This value may be a calibrated value rather than measured during the exposure.
Half Value Layer (0040,0314) 3 The thickness of Aluminum in mm required to reduce the X-Ray Output (0040,0312) by a factor of two. Note: This value may be a calibrated value rather than measured during the exposure.
Organ Dose (0040,0316) 3 Average organ dose value measured in dGy during the acquisition of this image. Note: This may be an estimated value.
Organ Exposed (0040,0318) 3 Organ to which Organ Dose (0040,0316) applies. Defined Terms: BREAST GONADS BONE MARROW FETUS LENS Note: The anatomic regions described by these terms are those that are particularly radiosensitive and for which it is conventional to obtain organ specific dose parameters.
Anode Target Material (0018,1191) 3 The primary material in the anode of the X-Ray source. Defined Terms: TUNGSTEN MOLYBDENUM RHODIUM
Include ‘X-Ray Filtration Macro’ Table C.8.35a
Rectification Type (0018,1156) 3 Type of rectification used in the X-Ray generator. Defined Terms: SINGLE PHASE THREE PHASE CONST POTENTIAL
Include Table 10-23 ‘Exposure Index Macro’

C.8.7.9 X-Ray Generation Module

This Module describes the attributes related to generation of X-Rays during the acquisition of an X-Ray image.

Table C.8-34X-RAY GENERATION MODULE ATTRIBUTES

Attribute Name Tag Type Attribute Description
KVP (0018,0060) 3 Peak kilo voltage output of the X-Ray generator used.
X-Ray Tube Current (0018,1151) 3 X-Ray Tube Current in mA.
X-Ray Tube Current in µA (0018,8151) 3 X-Ray Tube Current in µA.
Exposure Time (0018,1150) 3 Duration of X-Ray exposure in msec.
Exposure Time in µS (0018,8150) 3 Duration of X-Ray exposure in µsec.
Exposure (0018,1152) 3 The exposure expressed in mAs, for example calculated from Exposure Time and X-Ray Tube Current.
Exposure in µAs (0018,1153) 3 The exposure expressed in µAs, for example calculated from Exposure Time and X-Ray Tube Current.
Exposure Control Mode (0018,7060) 3 Type of exposure control. Defined Terms: MANUAL AUTOMATIC
Exposure Control Mode Description (0018,7062) 3 Text description of the mechanism of exposure control. May describe the number and type of exposure sensors or position of the sensitive area of the imaging detector.
Exposure Status (0018,7064) 3 Whether the exposure was normally completed or not. Defined Terms: NORMAL ABORTED
Phototimer Setting (0018,7065) 3 Nominal percentage phototimer setting, where a more positive value indicates greater exposure and a more negative value indicates less exposure.
Focal Spot (0018,1190) 3 Nominal focal spot size in mm used to acquire this image.
Anode Target Material (0018,1191) 3 The primary material in the anode of the X-Ray source. Defined Terms: TUNGSTEN MOLYBDENUM RHODIUM
Rectification Type (0018,1156) 3 Type of rectification used in the X-Ray generator. Defined Terms: SINGLE PHASE THREE PHASE CONST POTENTIAL
Generator ID (0018,1005) 3 Identifier of the generator

C.8.7.10 X-Ray Filtration Module

This Module describes the attributes related to the filtration of X-Rays during the acquisition of an X-Ray image.

Table C.8-35X-RAY FILTRATION MODULE ATTRIBUTES

Attribute Name Tag Type Attribute Description
Include ‘X-Ray Filtration Macro’ Table C.8.35a

Table C.8-35aX-RAY FILTRATION MACRO ATTRIBUTES

Attribute Name Tag Type Attribute Description
Filter Type (0018,1160) 3 Type of filter(s) inserted into the X-Ray beam (e.g. wedges). Defined Terms: STRIP WEDGE BUTTERFLY MULTIPLE NONE Note: Multiple type of filters can be expressed by a combination, e.g., BUTTERFLY+WEDGE.
Filter Material (0018,7050) 3 The X-Ray absorbing material used in the filter. May be multi-valued. Defined Terms: MOLYBDENUM ALUMINUM COPPER RHODIUM NIOBIUM EUROPIUM LEAD
Filter Thickness Minimum (0018,7052) 3 The minimum thickness in mm of the X-Ray absorbing material used in the filters. May be multi-valued, with values corresponding to the respective values in Filter Material (0018,7050).
Filter Thickness Maximum (0018,7054) 3 The maximum thickness in mm of the X-Ray absorbing material used in the filters. May be multi-valued, with values corresponding to the respective values in Filter Material (0018,7050).
Filter Beam Path Length Minimum (0018,7056) 3 The minimum length (in mm) of the X-Ray beam path in the Filter Material that is not blocked by collimation. May be multi-valued, with values corresponding to the respective values in Filter Material (0018,7050).
Filter Beam Path Length Maximum (0018,7058) 3 The maximum length (in mm) of the X-Ray beam path in the Filter Material that is not blocked by collimation. May be multi-valued, with values corresponding to the respective values in Filter Material (0018,7050).

C.8.7.11 X-Ray Grid Module

This Module describes the attributes related to the use of a grid to reduce scatter of X-Rays during the acquisition of an X-Ray image.

Table C.8-36X-RAY GRID MODULE ATTRIBUTES

Attribute Name Tag Type Attribute Description
Grid (0018,1166) 3 Identifies the grid. May be multi-valued. Defined Terms are: FIXED FOCUSED RECIPROCATING PARALLEL CROSSED NONE
Include ‘X-Ray Grid Description Macro’ Table C.8-36b

Table C.8-36bX-RAY GRID DESCRIPTION MACRO ATTRIBUTES

Attribute Name Tag Type Attribute Description
Grid Absorbing Material (0018,7040) 3 The X-Ray absorbing material used in the grid.
Grid Spacing Material (0018,7041) 3 The spacing material used in the grid.
Grid Thickness (0018,7042) 3 The thickness in mm of the X-Ray absorbing material used in the grid.
Grid Pitch (0018,7044) 3 The pitch in mm of the X-Ray absorbing material used in the grid.
Grid Aspect Ratio (0018,7046) 3 Ratio of the vertical spacing and horizontal spacing of the X-Ray absorbing material used in the grid. Specified by a pair of integer values where the first value is the vertical size, and the second value is the horizontal size.
Grid Period (0018,7048) 3 Period in mSec of reciprocation cycle. Only meaningful if a value of Grid (0018,1166) is RECIPROCATING.
Grid Focal Distance (0018,704C) 3 Focal distance in mm of a FOCUSED grid.
Grid ID (0018,1006) 3 Identifier of the grid