# How to calculate position in MPR?

**URL:** https://discourse.vtk.org/t/how-to-calculate-position-in-mpr/7909
**Category:** Support
**Created:** [February 24, 2022, 7:23am UTC](https://discourse.vtk.org/t/how-to-calculate-position-in-mpr/7909 "2022-02-24T07:23:46Z")
**Posts on this page:** 1
**Page:** 1

<div class="post-metadata">

### Author: ![zhang-qiang-github](https://discourse.vtk.org/user_avatar/discourse.vtk.org/zhang-qiang-github/32/2519_2.png) [@zhang-qiang-github](https://discourse.vtk.org/u/zhang-qiang-github)
#### Post date: [February 24, 2022, 7:23am UTC](https://discourse.vtk.org/t/how-to-calculate-position-in-mpr/7909/1 "2022-02-24T07:23:46Z")

</div>

I am implementing MPR (multiplanar reformation) in my project. I have finish all the calculation except the position. For example, the RadiAnt display position as:

 ![image](https://discourse.vtk.org/uploads/default/original/2X/3/37eb3bbf230a77dad24f92af444fe6002c8537f0.jpeg)

I understand the charact of R/L/A/P/S/I as:

```auto
R: right
L: left
A: Anterior
P: Posterior
S: Superior
I: Inferiro

```

Also, dicom has a tag: [‘Patient Position’](https://dicom.innolitics.com/ciods/mr-image/general-series/00185100#) to record the position in scanning.

My question is: how to calculate the position in MPR (`R/L/A/P/S/I`)?

Let’s say, the `Image Orientation (0020|0037)` is: `x=[cos(80°) sin(80°) 0], y=[cos(10°) sin(10°) 0], z=[0, 0, 1]`, and the `Patient Position` (0018|5100) is `HFS`.

1. Is it means that the `RL` direction is `x=[cos(80°) sin(80°) 0]`, `AP` direction is `y=[cos(10°) sin(10°) 0]`, and `SI` direction is `z=[0, 0, 1]`?

2. How to obtain the position when rotate the MPR direction? For example the following picture, how to obtain the `SR`/`IL`?

Any suggestion is appreciated~~~