# Contrast Control in DRR Generation Module

**URL:** <https://discourse.slicer.org/t/contrast-control-in-drr-generation-module/26527>\
**Category:** Support\
**Created:** [December 1, 2022, 4:01am UTC](https://discourse.slicer.org/t/contrast-control-in-drr-generation-module/26527 "2022-12-01T04:01:05Z")\
**Posts on this page:** 1\
**Page:** 1

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**Author:** ![fieldr4](https://avatars.discourse-cdn.com/v4/letter/f/439d5e/32.png) [@fieldr4](https://discourse.slicer.org/u/fieldr4)\
**Post date:** [December 1, 2022, 4:01am UTC](https://discourse.slicer.org/t/contrast-control-in-drr-generation-module/26527/1 "2022-12-01T04:01:06Z")

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I am attempting to create clinical-quality simulated XRs of the lumbar spine using the `DRR Generation` module. Unfortunately, my application prevents me from using the volume renderer for DRR generation.

I have selected realistic SID, SAD, and imager values, but the resulting images have very poor contrast. Here are two examples. I exported them from Slicer as .mha files and then converted them to .png files using ImageJ.

 ![563_DRR_Coronal](https://us1.discourse-cdn.com/flex002/uploads/slicer/original/3X/a/5/a57a8b278b1761ea6967faaa89895041bb72f421.jpeg)

 ![563_DRR_Sagittal](https://us1.discourse-cdn.com/flex002/uploads/slicer/original/3X/5/a/5a8dfd886fdf81885e7e84654aec1bd8e31e0bb1.jpeg)

Does anyone have any recommendations?

I am unable to crop the CT volume to remove some of the soft tissues because the coordinates of the CT are not in LPS (thanks @lassoan and @Mik for helping me figure that out). I can fix the original CT’s coordinate reference frame, but when I create a new cropped volume from it the resulting volume’s coordinate reference frame is not correct for the `DRR Generation` module.

Is there a way to threshold the original CT volume without creating a new volume?