Horos is free, open-source software that makes medical image viewing accessible for users across the globe. Purview, the Chief Sponsor of Horos has maintained and supported the Horos Project for nearly a decade, facilitating more than a million downloads across hundreds of countries. 

Purview’s support team receives questions about Horos every day, troubleshooting all of the paid and even unpaid inquiries on behalf of Horos. To help the Horos community make the most of their free desktop medical image viewer, the Purview team put together a list of the top 10 questions they receive most often and their answers.

1. Where can I download the different versions of Horos?

You can choose whether you’d like to donate to Horos, fill out the form, and then download Horos here. Horos is a free, open-source software that functions entirely on donations from the Horos community and appreciates your donations! 

2. What is the difference between the “Latest Version”  and the “Release Candidate” of Horos? Which version should I be using?

The “Latest Version” is a version that has officially been used and tested by end users in the Horos community. The “Release Candidate” is the next iteration in the Horos evolution currently undergoing testing.  The biggest difference is that the Release Candidate is available to the community to provide feedback to us. If you download this version and experience issues, please send us an email and let us know: experts@horosproject.org

3. Why does the MPR tool cause Horos to crash sometimes?

If you are noticing that using the MPR tool causes Horos to crash, the issue is most likely due to software version conflict. When users update their OS or purchase a new Mac device, a different version of Horos may be necessary to be the most compatible to your OS or device.  The current recommendations are shown right. Download versions of Horos here. 

4. How do I send to Horos or query and retrieve to Horos?

Sending to Horos or query and retrieving to Horos is accomplished with DICOM network routing. Horos has the ability to connect to your imaging modalities or PACS using C-STORE protocols. Once configured, users can route their images to the Horos app, send images from the Horos app to another destination, or query and retrieve specific studies to the Horos app.

5. I added a new file to Horos and now it keeps crashing. What do I do?

You should open Horos in “safe mode” and remove the most recently added study. To do this you should press: Shift + Option + click the Horos app to open in Safe mode. This will open Horos but unlink the database, allowing you to rebuild the database, delete a corrupt study that was recently added, or to roll back any setting that may have previously crashed Horos, preventing it from opening.  Since the database is unlinked, images are not viewable when opened during “Safe Mode.”

6. What is the difference between “copy files” and “copy links?"

The main difference is that “copy files” permanently adds files to the Horos database, while “copy links” provides short term access to the files directly. When adding new studies to Horos, users are given the option to “copy files” or “copy links.”  Selecting “copy files” will permanently add the study to the Horos database, reducing the local storage on the Mac hard drive.  Selecting “copy links” allows Horos to temporarily access the links to view the images but it does not permanently add the study to the database.  

7. Is there a fix for issues when importing files directly from Dropbox?

Most issues importing files from Dropbox are associated with the settings not being set to make the files available offline from the Dropbox account. When using the "drag and drop" functionality from a Dropbox account to the Horos application, the activity window in Horos will show files processing but the study is never added to the database, confusing the user. However, if the settings are adjusted from the Dropbox account to make files available offline, the drag and drop feature should add the studies to the Horos database without issue.   

8. How do I remove unwanted Database sources?

To remove unwanted database sources, in your Finder Window go to: 
Preferences/Locations > Local > Horos Database and then delete entries

The Sources window in Horos (where additional databases are shared and are visible) can get inundated with past local paths where studies were accessed or stored.  This is especially true working with CDs or USB thumb drives.  You can remove unused locations or history by accessing the Locations menu of the Preferences screen. 

9. What do I do if I lost files and don’t know where they went?

While this can occur for multiple reasons, the most common issue we see is that the user has set up their Apple devices to sync files and images. When the file is deleted from another device, it syncs, deleting the shared image from the device using Horos. To prevent this from occurring, we recommend that you change your settings to not sync files used in your Horos database.

10. What if I still need help or have questions?

In addition to the solutions shared in this article, the Horos download page contains some troubleshooting instructions for common issues. If none of these troubleshooting steps worked for you, we suggest reporting the issue on Github, posting your question on the Google Groups Horos Community page, or if necessary, reaching out to Horos Paid Support for help.

Remember: Horos is a free, open source, desktop viewer designed to work on Macs only. If you are looking for any of the below features/ functions, we recommend checking out Purview Image™. 

• A viewer that works with Windows or other operating systems

• A central system from which you can securely share and receive studies online

• The ability for patients and colleagues to self-serve by uploading studies directly to your cloud

• Automatic uploading to your cloud from your modalities 

• Secure backup/recovery cloud storage

• An FDA approved viewer for primary diagnosis

• And more..

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Help Us to Keep Horos Free

Please keep in mind that since Horos is a free, open-source software, it functions entirely on donations from the Horos community and volunteers. Purview is a proud sponsor of Horos and attempts to improve the code base regularly by incorporating feedback from the community into future versions. We also try to regularly share resources and information so the Horos community can get the most out of the application. However, as technology advances, it takes more time and investment to bring Horos up to speed. When less than 5% of Horos users financially contribute to the project, it is more difficult to maintain Horos and provide future fixes. Please understand that we want to support Horos for as long as possible, but do require financial support to keep it going. If Horos has been useful to you and you would like to donate, you can do so here or by clicking the button below.