# DICOM Standard Browser

Built with by Innolitics, a team of medical imaging software developers.

Data synced with official DICOM standard on 12 May 2020. The DICOM Standard is under continuous maintenance, and the current official version is available at http://www.dicomstandard.org/current/. DICOM Parts 3, 4, and 6, © NEMA. Please note that the most recent PDF version of the standard is the official reference, and should checked when making technical decisions.

## Gantry Pitch Rotation Direction Attribute

Tag (300A,014C) Conditionally Required, Empty if Unknown (2C) GantryPitchRotationDirection 1 Code String (CS)

Direction of Gantry Pitch Angle when viewing along the positive X-axis of the IEC GANTRY coordinate system, for segment following Control Point. Required for first Item of Control Point Sequence, or if Gantry Pitch Rotation Direction changes during Beam. See Section C.8.8.14.8 and Section C.8.8.25.6.5.

Enumerated Values:

CW

clockwise

CC

counter-clockwise

NONE

no rotation

## Section C.8.8.14.8

##### C.8.8.14.8 Machine Rotations

For the machine rotation angles Gantry Angle (300A,011E), Beam Limiting Device Angle (300A,0120), Patient Support Angle (300A,0122), and Table Top Eccentric Angle (300A,0125), rotation direction is specified as clockwise (CW), counter-clockwise (CC), or NONE. The maximum permitted rotation between two Control Points is 360 degrees. Examples:

1. Gantry Angle moves from 5 degrees to 5 degrees, Gantry Rotation Direction = NONE:

No movement.

2. Gantry Angle moves from 5 degrees to 5 degrees, Gantry Rotation Direction = CW:

Full clockwise rotation (360 degrees).

3. Table Angle moves from 170 degrees to 160 degrees, Table Rotation Direction = CC:

Counter-clockwise rotation by 350 degrees (note direction of increasing table angle as defined by IEC 61217).

## Section C.8.8.25.6.5

###### C.8.8.25.6.5 Gantry Pitch Angle

The Gantry Pitch Angle is not defined in IEC 61217. This angle is defined in the DICOM Standard in a way compatible with the current notion of IEC by introducing it as rotation of the IEC GANTRY System as indicated below.

The Gantry Pitch Angle is defined as the rotation of the coordinate axes Yg, Zg about axis Xg by an angle ψg; See Figure C.8.8.25-7. An increase in the value of angle ψg corresponds to the clockwise rotation as viewed from the isocenter along the positive Xg axis

Figure C.8.8.25-7. Gantry Pitch Angle