What Is The Best License Model For Horos?



Dear Horos Users and Developers,
As one of the Horos contributors and curators, I want firstly to thank you all for your adoption of Horos, and the donations you have been making to the project. As you may know, we have over 80,000 people using the product at this time, growing by over 5,000 per month. Your loyalty and help is appreciated. 

The main reason I’m writing to you is to hear your opinion and start a discussion of what could be an improved license model for Horos. Many plugin developers have contacted me saying they would love to contribute proprietary libraries and plugins, but the Horos GPL license is too restrictive and would lead them to have to release their source-code into the public domain. According to the GPL license, and in simple terms, when binary code is linked statically or dynamically to a GPL code project, the binary needs to have the source code released under the GPL terms. I have seen different interpretations but, all in all, this leads to a quicksand territory.

The OsiriX project was licensed originally as GPL too; later it switched to LGPL. As a long-term OsiriX adopter, I evidenced a considerable number of plugins becoming available in OsiriX and some of them with proprietary code. Even OsiriX had some third-party codecs integrated to it, which added significant improvement to image decoding performance. That was mainly possible because of the LGPL transition the OsiriX maintainers made effective.

So why is Horos not LGPL? First of all, the fact Horos is not LGPL is not related to any private or commercial intention of our main sponsor, Purview. Purview already confirmed, and emphasized, that the company has no reason/intention to make Horos a closed-source project. Even if they were to pursue FDA, CE or other regulatory approval, they could do so with an open source project. In fact, we hope someday they do head in that direction.

That said, and back to our question “So why is Horos’ license not LGPL?”. The GPL licensing Purview has chosen is based upon the notations that they found in the open source code at the time of their fork.  Even though OsiriX had clearly stated that the open source code license had changed to LGPL, they did not update all the source code to reflect that. In fact, Purview wasn’t convinced that OsiriX had sufficient authorization from each of its contributors to change from GPL to LGPL (which would have been required to make this change). So they seem to be stuck in a quandary. The Horos Project wants to abide by FOSS licensing conventions but is unsure of whether the original copyright holders of the GPL code would agree to the change.

That’s where we would like to hear your comments. Which is the best license model for Horos? LGPL? Which are the implications of this transition? Are any of you copyright holders in any of the former OsiriX modules? Do you know of any who would be impacted by such a change.

In advance, I thank all the users, developers, and the license experts that can shed some light or opinion to this discussion.


Best Regards

Fauze Polpeta

Horos - GPL or LGPL?

How To Connect Horos And OsiriX To A Multi-Location Environment


We are frequently asked by Horos and OsiriX users about configuring their practice to use their preferred desktop viewer in multiple connected instances within their enterprise. While each situation is a bit different, below are some basic configurations and considerations for establishing multiple connected instances of OsiriX or Horos.

Why Even Connect Multiple Horos or OsiriX Instances?

Many OsiriX and Horos customers use their desktop viewers for their own ad hoc image viewing. However, we are finding that more and more more physicians (and veterinarians for that matter) want to store their studies, so they can be accessed from multiple workstations; either in the same office or in multiple disconnected geographies. The alternative of course would be throwing away their existing solution, and investing in a brand new but more expensive one. Plain and simple, this category of clients wants to retain their Horos or OsiriX workstations as their viewers. By creating an architecture where workstations access a central or Cloud PACS, each workstation can be assured of access to every image in the practice.

But Remember, They Weren’t Built To Be A PACS

We have found that it’s not uncommon to see practices establishing their entire PACS infrastructure around Horos and OsiriX.  For instance, some organizations place viewers in conference rooms to view and collaborate on cases. Others use viewers in patient treatment rooms in order to display and discuss studies with a patient.  And of course, we’ve seen plenty of clients do their radiological reads and reports on these workstations. Overall, with a Horos or OsiriX desktop in each location: they become the standard viewers throughout the enterprise.

So, it’s no surprise to us that our customers love these viewers on their workstations.  We do too. However, what we don’t love, is the idea of using them as a PACS.  We’ve written extensively about why we suggest you not rely on either Horos or OsiriX for that usage. In fact, neither was built to be an enterprise PACS. So, here are some tips as to how to ensure a strong architecture for your medical imaging solution.

Download ViVA Guide

If You Are Connecting to a Central PACS

Depending upon the expanse of your geography, you will either connect your workstations to an on-site central PACS or a Cloud-based PACS.  If you are connecting to an on-site PACS you will need to physically connect each workstation to the server via a local area network (LAN) connection. That is, if all the workstations are proximate to the server. If not, you will connect via a virtual private network (VPN). A LAN connection operates as a direct wired connection, usually in the same office.  A VPN, on the other hand, is typically used with a remote workstation. This enables you to use the Internet while maintaining the privacy of a direction connection.

Note that each workstation that is connected to the central PACS will be able to query and retrieve studies from that PACS. The viewers and PACS will need to be configured to ensure they each acknowledges the presence of each other. In which case, software switches need to be set. This is where you start talking about C-GET and C-MOVE…but that’s another blog.

If You Are Connecting to the Cloud

An alternative to an on-site central PACS is a Cloud-based PACS.  The configuration of the workstation viewers in this case is similar to that of an on-site PACS.  If the information contained in your PACS includes private health information, you likely will connect your workstations to the PACS using VPNs. This enables a basic Internet connection to operate securely.

The difference between an on-site PACS vs Cloud PACS is SAM: sharing, access, and mobility.

Sharing– With a Cloud based solution, you can easily and instantly share a study with a colleague or patient.

Access–  It doesn’t matter if you are at the airport, on vacation, or commuting – just get on your MacBook to instantly view a study. You can now achieve what you would at the office…except you no longer have to physically be at the office.

Mobility– You can supplement your OsiriX or Horos viewer with a web-based viewer that will enable you to view studies even if you don’t have your MacBook with you. That’s right, you can use a browser on any device – even a tablet or smartphone, to view your study!

Configure Your Viewer Settings

So, let’s say that you currently have two desktop viewing stations connected to a LAN and want to connect them to a central PACS. The way you would connect them is pretty simple assuming your PACS was set up correctly. All you do is go into the settings for your viewer, go under location, and enter in the destination for the PACS. This includes the following information: AE title, Port, and IP address.

If you want to connect to the Cloud, you just go one step further. This part will vary depending on whether you are a physician or veterinarian.

Physicians: You would normally establish a VPN with your Cloud vendor. As we mentioned before, a VPN provides a secure connection with the Cloud using a standard Internet connection. Then you would follow the same steps as you would with an on-site PACS: define the destination of your PACS on your viewer settings. Again, just enter in the AE title, Port, and IP address. That’s it.

Veterinarians: Typically, you wouldn’t even need a VPN. You would instead be provisioned with a public IP address, following the same viewer settings processes as above.

Final Thoughts

If you love to use Horos or OsiriX and want to incorporate it in your enterprise, don’t worry- it’s not rocket science. We first recommend that if you don’t already have one – get a PACS, either on-site or in the Cloud. Horos and OsiriX were not built to be a PACS, so avoid disaster and risking permanent loss of your medical images. Once you have a PACS, your IT department or your PACS vendor can customize the settings within your desktop viewers. By doing so, you keep using your preferred desktop viewer;  but additionally, you can use it within your existing solution, and save money rather than moving to an expensive alternative.

Webinar Sign Up - Graduating From Horos & OsiriX

Need More Storage For Medical Images With Horos and OsiriX?


Personal computers have come a long way since their introduction at the end of the 1970’s.  They are now quite powerful machines with retina displays, increased performance, and abundant data storage. So naturally, physicians who work with medical images gravitate toward their PC as a way to save money rather than purchase an expensive purpose built medical imaging viewing station from one of the big name vendors. When you compare the capabilities of desktop viewing software like OsiriX or Horos to more expensive viewers, most physicians will find that these programs do just fine and that the extra expenditure is not warranted. We agree. In fact, if you want to see even sharper images, invest in a large high resolution monitor rather than a purpose built workstation. You can find a great monitor for less than $1,000 USD nowadays. However, storing studies on your trusty PC is probably not the best idea due to one simple fact: there’s simply not enough room.

Should My PC House My PACS?

If you chose your PC as a viewing station, then a logical question arises as to whether to just use the PC as a complete PACS.  With PC storage regularly exceeding a quarter of a terabyte, why not just keep the electronic files of your medical images right there? After all, the viewing software comes with the ability to store your studies locally.  So with that viewer functionality and the available storage on your PC, there should be plenty of room, right?  Well, we did the calculations and even with storing high resolution MRIs and CTs, a quarter of a terabyte of storage (250 gigabytes) can comfortably house about 1,250 studies. Hence, if you storing 25 new studies each month, that space could theoretically last you more than 4 years.

You’re probably wondering at this point, “So, what’s the problem? You’re telling me my PC has the capability to do what I need. Why should I even bother to change the way I currently store studies?” It’s a valid question, and many have asked it before. Here’s why we recommend that you don’t fall into the same trap….

The ugly truth is that your PC’s hard drive and solid state storage (SSS) are points of failure. If your drive or PC crashes, all of the images you have stored are at risk.  Of course you could back them up regularly to protect them.  But most of the health care providers we have encountered either fail to regularly backup their data with a reliable method, or fail to test those backups to ensure they are recoverable. In light of that experience, we suggest that you not use your PC as a PACS.

Download ViVA Guide

Is There A Cheaper Alternative?

An alternative to storing medical images on your PC is a relatively inexpensive on-site PACS. You should be able to find an affordable configuration at the smallest end for less than $2,500 USD.  -Even the larger systems can all be purchased for less than $5,000. Typically these are comprised of a computer server connected with direct attached storage in the form of a RAID. This system would run the PACS software along with a SQL database to store your images.

However, do note that the size of your RAID is dependent upon the volume of images you are planning to capture. Below is a table that we created for typical monthly and annual usage along with the recommended RAID size.  You should note that due to the “redundancy” inherent in a RAID, not all of the space is “usable” for storage of studies.  Those calculations are built into the chart below.


While a standalone PACS is far better than using your PC, we always suggest that you backup your RAID as well.  Despite the disk redundancy, we are not fans of having all of your data in one geography, no matter how resilient it is. You should always be prepared for any type of disaster: natural or man made. Good procedures include automatic backups set on a regular frequencythat send your data to another location. In fact, the Cloud is a great facility for backing up your PACS.

Final Thought

There is nothing wrong with using a solution that works for you. If OsiriX or Horos fall into that realm, then that’s great! All we advise is that you take the time to consider the risk. Technology is not perfect, and if you leave your PC to work as your PACS without a sufficient backup strategy, you’re tempting the permanent loss of your data. PCs are powerful machines, but they were not created to hold large amounts of data forever. For one, their lifespans are quite short. Additionally, they can break, be lost or even stolen. If that happens, you lose your data forever. And if your preferred desktop viewer is the only reason you really want to use your PC as your PACS, you have been misled. For a small cost, you can upgrade to an on-site or Cloud based PACS. The latter of which will allow you the ability to share and access your medical images anywhere in the world. So even if you left your PC at the office, you can view your studies from your couch on your personal tablet….Now isn’t that a nice thought?

Webinar Sign Up - Graduating From Horos & OsiriX

Save Time and Lives. Update The Way You Share Medical Images.


Here’s the thing, we often talk about sharing and its value in the theoretical sense in our blogs. For us, sharing is an important part of fulfilling our mission of enabling the availability of medical images wherever and whenever they are needed for patient diagnosis and treatment. Of course, being in this industry means that over time we have seen and heard our fair share of real life accounts where the immediate ability to share studies has led to significantly improved medical outcomes. That being said, we have also found that there are cases when a local onsite PACS as the sole solution for sharing medical images has led to hindered medical outcomes.

Your Sharing Method Matters

Typically on-site PACS share via CDs. When CDs are involved, not only does the quality of treatment suffer, but you end up racking up your bill. This includes the cost of the CDs, the CD publisher, the time that it takes for your staff to burn images onto those CDs, the postage, etc. Not only that, but it takes time for the images to get to their destination regardless who is transporting them: the patient or the post office. By the time the images get where they are needed, often the CDs don’t work with the system at the specialist’s office. The CD itself is scratched or damaged or even if the patient arrived 30 minutes early for their appointment, the CD never got there. All of which causes a delay in treatment. For patients suffering from a stroke, aggressive cancer, or other time sensitive conditions, time is of the essence. It’s undeniable; and if that treatment is postponed due to medical images not being available, it most certainly leads to a disappointing appointment, and in some cases: the difference between life and death. With the Hippocratic Oath, you vow that you will do the best to your ability to treat a sick human being. So why ignore the ugly truth? Sharing images with CDs does NOT enable efficient and effective medical treatment in time sensitive cases. This method is not only expensive to you, but can cost your patients their health. So the next time you look at your Horos or OsiriX viewer and consider it as the best solution available to you, think again. You’d be surprised to learn that a Cloud integration with your current solution would actually save you money. 

Download ViVA Guide

A Real Life Scenario

Over the years, we have ran into countless real life examples of how sharing improves medical outcomes. Here is one of the many…

Abigail, a  healthy 48-year-old woman visited a local outpatient imaging center to have some scans done due to investigation worthy symptoms. However, what started off as a routine visit ended up being a surprise diagnosis of kidney cancer. After a series of tests and specialists visits, Abigail’s cancer was determined to be inoperable and untreatable by FDA approved treatment protocol. Her family scrambled for alternatives and found an out-of-town clinical trial that would accept her. However, in order to join the trial, she needed to immediately assemble all of her scans and take them to her clinical trial location. Abigail had her scans done at 3 separate imaging center locations. So in the short amount of time that spanned her diagnosis to admission into the trial, and the commencement of the clinical trial, Abigail had to return to each location to collect CDs. However, the world doesn’t revolve around a diagnosis. Like any other patient with such a condition, Abigail had a life and a family to factor into the equation. Aside from making the arrangements to get her into the trial, Abigail and her husband had to ensure that their young children would be taken care of during their absence.

Every outsider looking in thinks that getting a copy of their medical images should be a quick and easy process – no appointment necessary. The reality of it is quite the opposite. For Abigail, it required numerous phone calls and hours spent waiting while the overworked staff at each location scrambled to get the right images burned onto CDs. At one location, the CD publisher itself was malfunctioning, so it took numerous visits before the device was able to burn the CDs needed. Once the couple had the images, they delicately packed the CDs and headed to the clinical trial. As requested, they arrived 30 minutes early to fill out paperwork and submit their images, and after an hour wait, the physician saw them. Abigail and her husband had spent thousands of dollars on airfare, the care for their children, lodging, as well as the expenses for the trial itself. Upon seeing Abigail, the physician informed her that a CD provided by one imaging center would not work on their system, so he could not read the images. Another CD had the WRONG studies on it. Instead of the scans and reports about her kidneys, the CD contained x-rays from a broken arm…an incident from years ago. Understandably, everyone in the room was frustrated. As you know, getting a seat in a clinical trial is not an easy task. There are often waiting lists. Fortunately for Abigail, they were able to get the images overnighted from the imaging centers – which of course ran a high bill at those locations.

So consider this – if instead of relying on technology from the 1900’s, what if those imaging centers could have simply clicked one button on their workstation and virtually send those images to the clinical trial location? It would take SECONDS versus the number of days that the CDs took. It would take one attempt versus the numerous for the CDs. It would have allowed the physicians at the trial to view Abigail’s images weeks before she even arrived to establish a preliminary plan of action for her variety of cancer. However, that time was lost. Once the images arrived via parcel, they were not read until the next day. With a Cloud solution, if the images had been shared virtually, the team could have read those images that evening at home, on a tablet, or other personal device even. It would have expedited the process. Unfortunately, the physician never had the opportunity to provide the best care to his ability for this patient – all due to the method of sharing images.

Abigail is doing well now, but while her journey still has hope, not all stories end with a happy ending. Think about it, Abigail had a couple of months between her diagnosis and the beginning of her trial. What if her cancer had spread to neighboring organs and compromised her prognosis furthermore? The hospital holding the clinical trial would not learn of this until the day of her appointment do to the lack of availability of images. However, if the images had been shared with the Cloud, the moment she was accepted, things would be different.

Final Thought

A local on-site PACS is not a terrible solution. Each practice is unique and if an on-site PACS works well with your workflow, then that’s great! However, if you are an imaging center or practice that does have to share medical images with other physicians for patients with time sensitive conditions, consider the Cloud. Sharing is critical to optimizing medical outcomes. Depending on the type of condition, it can mean the difference between life and death, or the quality of life that patient will lead after an incident. Having immediate access to medical images allows you to provide efficient and effective care to your patients. Besides, the best part of sharing with the Cloud (aside from saving lives of course) is the ability to access those shared images anywhere in the world, at any time, on any device.

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Purview Surpasses 1 Million Patients on Medical Imaging Platform


Annapolis, MD – Purview, a growing healthcare technology provider of medical imaging access solutions, announced today that it has exceeded 1 million patients on its medical imaging access platform, Purview ViVATM, in just 3 years since its launch. Purview has now processed over 175 million medical images through ViVA and is adding a new image every second and a new patient every 2 minutes.  At this pace, Purview will add 1 new patient to its platform and process 120 new images in the time it takes you to read this press release.


Les Trachtman, Managing Director of Purview, the patient driven medical imaging company
Les Trachtman, Managing Director

“Surpassing one million patients is a testament that Purview has become a critical curator of rich diagnostic data for medical professionals worldwide,” said Les Trachtman, Managing Director of Purview. “It’s a profound responsibility to be the steward of patients’ confidential medical data but we pride ourselves in our ability to make information instantly and securely available whenever and wherever it is needed.”


Purview ViVA is a cloud-based solution that expedites patient care and improves medical outcomes by enabling physicians and patients to gain anywhere, anytime access to medical images, such as X-rays, CT scans, and ultrasounds. By enabling access and expertly curating diagnostic medical data, Purview is changing the medical imaging landscape for physicians and patients alike. Through Purview ViVA, physicians can expedite diagnoses, compare images to previous studies, and collaboratively review records with other physicians. Patients using ViVA can direct their medical information to specialists for second opinions, aggregate their historical record of past procedures, and ensure that their medical information follows them if they move or while they travel.


Purview Founder Phil Jackson
Phil Jackson, Founder

“A physician or patient can share complex and dense health records on-demand with a single click on our platform,” said Phil Jackson, Founder of Purview.

Purview has become a trusted leader in the medical imaging industry, increasing its client base by more than 100% over the past year while now globally serving more than 200 institutional client partners across North America, South America, Europe, Asia, and Australia.



About Purview

Purview is an Annapolis, Md.-based technology company focused on enhancing how physicians and patients view, access, transport, archive, and share medical images such as X-rays, MRIs, CT scans, and ultrasounds. Purview’s mission is to improve medical outcomes by enabling rich diagnostic data to be viewed and shared anywhere, anytime on any device.  To learn more about Purview and its innovative solutions, please visit


For More Information:

Craig Dykstra
[email protected]

New Horos Release Candidate

Hello community!

Thank you for your continued help and support. If you haven’t heard yet, we have a new release candidate available: Horos 2.0. In our latest version, we have made some major improvements to the stability of the application, fixed DICOM tag editing errors, and refactored the plugin manager. We ask you to please download and submit any issues with the latest release candidate for 2.0.

Please click here to download and here to submit any issues to our Github Repository.

REMINDER: If you haven’t done so yet, please take a few moments to fill out our 2o16 Horos User Survey. Click below to complete the survey before Monday, June 6th!

Complete the 2016 Horos User Survey

Fill out the Horos 2016 User Survey!

We want to hear from all Horos Users!

We’re excited to announce the release of our 2016 Annual Horos Users Survey.

Your experience with Horos is important to us. It’s our goal to continue to provide Horos free of charge and to continue to curate the open-source project. Please take a few moments to give us feedback and comments in this important survey.

We will use the data to continue to make improvements and provide the community with insights about the more than 12,000 users worldwide.

Click Here to Complete Horos Survey

Make a donation to the Horos Project

First, we would like to say THANK YOU to the entire Horos community for continuing to use and support the open source project. The Horos community has grown to over 11,000 users since we started the project in February 2015.

Your support, development contributions, and feedback have helped to continue improving Horos. If you’ve been following the Horos Github repository, you will notice progress and improvements being made for the next release.

Horos is community-driven, open source project that is made available for free. We want to continue making the software available for free as well as dedicate more resources to helping address issues and improve the platform. That’s why we’re offering you to make a donation to the Horos Project.

By popular demand, we’ve added a donation option where you can donate any amount toward the project. Now you can sponsor a bug fix, feature request or just donate towards the cause! If you make a donation, 100% of your contributions will be matched by Purview. Click the button below to make a donation today.

Make a Donation

Update: Horos v1.1.7

Hey Horos Community!

We’ve released Horos v1.1.7. This latest version has implemented lots of backend optimizations and bug fixes. They include…

  • Thread memory management fix
  • Viewer opening notification fix
  • isPoint ROI method refactored
  • tLayer ROI width and heigh obtained from bitmap generated

Thank you for reporting bugs and helping the project. If you are experiencing a bug, please submit a report with an anonymized study and instructions on how-to replicate it. If you haven’t yet, download Horos here:


Horos 101 is in session!

Hey there Horos community!

We hope all goes well to the 9,000+ Horos users out there in the world. We’ve been getting a lot of interest in learning more about the Horos software and how to use it. So, we decided it was time to host some training sessions.

Starting next Tuesday, the Horos project will be hosting monthly webinars for users to learn more about Horos’ features and functions.

Can’t wait? Click below to register and learn more:

Horos Education