How to Use DICOM tags to determine the direction of 3D images

Http://blog.csdn.net/yonghong1/article/details/6004185

In DICOM, three tags are associated with the imaging direction.

Reference Source: kitware instructions on DICOM direction

Http://public.kitware.com/IGSTKWIKI/index.php/DICOM_data_orientation

 

 

Including

1. Image Position (0020,0032): Specifies the x, y, and z coordinates of the upper left hand corner of the image. in other words, this tag specifies the coordinates of the first voxel transmitted.

 

Image Position: indicates the spatial coordinates (x, y, z) of the First pixel in the upper left corner of the image ). That is, the coordinates of the first pixel of DICOM file transmission.

2. Image Orientation (0020,0037): Specifies the direction cosines of the first row and the first column with respect to the patient. the direction of the axes are defined by the patients orientation to ensure LPS System (x-axis increasing to the left hand side
Of the patient, Y-axis increasing to the posterior side of the patient and Z-axis increasing toward the head of the patient)

Image direction: indicates the direction of the first line and the first column of the image relative to the patient cosine. The axis direction is determined based on the patient's direction (the X axis points to the patient's left side, the Y axis points to the patient's back, and the Z axis points to the patient's head.

 

3. Patient Position (): Patient Position descriptor relative to the equipment. required for CT and MR images. possible values: HFP = head first-prone, hfs = head first-supine, hfdr = head first-decibitus right, hfdl = head first-decubiturs left, FFP =
Feet first-prone, FFs, ffdr, ffdl.

 

Patient location: the location that describes the patient relative to an imaging device such as CT or mr. HFP: head in front, prone; HFs: head in front, supine

 

Example:

A slice M:

 

99.8046875, 282.8046875 image position (patient):-94.25 /-/

1/0, 0/0 image orientation (patient): 1/0/

, Patient Position: Another HFS slice N:

 

 

99.8046875, 282.8046875 image position (patient):-157.5 /-/

1/0, 0/0 image orientation (patient): 1/0/

, Patient Position: HFS we found that only the Z axis coordinates of the image have changed, and the size of the Z axis shows that M slices know the direction of the image below n slices, it's easy to analyze the image behind it.