# I had trouble using SiddonJacobsRayCastInterpolateImageFunction
**URL:** https://discourse.itk.org/t/i-had-trouble-using-siddonjacobsraycastinterpolateimagefunction/5310
**Category:** Beginner Questions
**Created:** [September 1, 2022, 1:21pm UTC](https://discourse.itk.org/t/i-had-trouble-using-siddonjacobsraycastinterpolateimagefunction/5310 "2022-09-01T13:21:27Z")
**Posts on this page:** 2
**Page:** 1
### Author:  [@hcs027](https://discourse.itk.org/u/hcs027)
#### Post date: [September 1, 2022, 1:21pm UTC](https://discourse.itk.org/t/i-had-trouble-using-siddonjacobsraycastinterpolateimagefunction/5310/1 "2022-09-01T13:21:28Z")
I had trouble using SiddonJacobsRayCastInterpolateImageFunction. I could install itk and itk-twoprojectionregistration. I can find the SiddonJacobsRayCastInterpolateImageFunction module during dir (itk). But when I try to use SiddonJacobsRayCastInterpolateImageFunction module, error occurred. How can I do to solve this problems. Here is the error message.
KeyError Traceback (most recent call last)
in
3 PixelType = itk.D
4 ImageType = itk.Image[PixelType, Dimension]
----\> 5 dir(itk.SiddonJacobsRayCastInterpolateImageFunction)
6 #InterpolatorType = itk.SiddonJacobsRayCastInterpolateImageFunction[ImageType,itk.D]
~\anaconda3\lib\site-packages\itk\support\lazy.py in **getattribute** (self, attr)
134 for k, v in namespace.items():
135 setattr(self, k, v)
→ 136 value = namespace[attr]
137 else: # one of the other threads that had been blocking
138 # waiting for first thread to complete. Now the
KeyError: ‘SiddonJacobsRayCastInterpolateImageFunction’
---
### Author:  [@matt.mccormick](https://discourse.itk.org/u/matt.mccormick)
#### Post date: [October 7, 2022, 6:39pm UTC](https://discourse.itk.org/t/i-had-trouble-using-siddonjacobsraycastinterpolateimagefunction/5310/2 "2022-10-07T18:39:34Z")
Hi @hcs027 ,
Welcome to the ITK Community!
> KeyError: ‘SiddonJacobsRayCastInterpolateImageFunction’
This indicates the itk-twoprojectionregistration package may not be installed in your environemnt.