[BitBucket user: Marco Barnig]
[BitBucket date: 2019-05-03.20:47:46]

**What steps will reproduce the problem?**   
Upload the attached DICOM file radiologic.dcm to Orthanc server.

By adding the attached radiologic-dic.json file to the Orthanc configuration the private tags are displayed as expected in the Orthanc tag panel.



![](2583496647-orthanc-tags.jpg)
An extract of a dump created with the dicom3tool dciodvfy is shown below:

![](3173254069-radiologic-dump.jpg)
Execute the curl command

```
curl http://<ip-adress:port>/instances/f1c8c9de-c1f0dd83-a1de5468-03def2fe-c24d3589/modify -X POST -d ‘{"Replace":{"RadioButton3":"aaabbbccc"}}’ > modified-rest-api.dcm
```

or

```
curl http://<ip-adress:port>/instances/f1c8c9de-c1f0dd83-a1de5468-03def2fe-c24d3589/modify -X POST -d ‘{"Replace":{"4321,1012":"aaabbbccc"}}’ > modified-rest-api.dcm
```

The related Orthanc log file is attached as orthanc-trace-log.txt.

**What is the expected output?**

A new DICOM file with value in tag \(4321,1013\) changed from _jklmnopq_ to _aaabbbccc_.

**What do you see instead?**  
A new DICOM file with VR of tag \(4321,1013\) changed from LO to UN.

An extract of a dump created with the dicom3tool dciodvfy is shown below:

![](3565065530-modified-rest-api-dump.jpg)
When modifying the series, study or patient instead of the instance with the REST API, the result is the same.

**What version of the product are you using? On what operating system?**  
Orthanc 1.5.6 in Docker Linux, natif in Windows 10 and natif in OS X 10.13.6. Same results in all systems.

**Temporary solution:**   
As a workaround I can use my own callback in a plugin to modify the files. Here is my code snippet:

```
{ 
  string myDcmtkCommand = "dcmtk-3.6.4/bin/dcmodify -m '(4321,1012)=aaabbbcc' /temp/radiologic.dcm";
  int resultDcmtk = system(myDcmtkCommand.c_str()); 
  ... 
  return OrthancPluginErrorCode_Success; 
}
```

An extract of a dump created with the dicom3tool dciodvfy is shown below:

![](2363588212-modified-system-dcmtk-dump.jpg)
Another workaround consist in using the modified files with VR = UN, because I can read the hexadecimal content and convert it to a string.

Both methods are not very elegant.

**What are references?**   
My contributions in the Orthanc Forum dated April 9, 2019 \( [Managing private tags is tricky](https://groups.google.com/forum/#!searchin/orthanc-users/mbarnig%7Csort:date/orthanc-users/p5S4YkHcTrc/h8PgZ2seAgAJ) \) and June 1, 2016 \( [Questions about private tags](https://groups.google.com/forum/#!msg/orthanc-users/v60O7x3uYF0/tiuOQTBuAgAJ) \).