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PT Software – Why do RT and PT devices differ so much in control-room design?

David Pahor

This is the second article in the blog series “Developing great software for particle therapy systems”. Particle therapy (PT) devices are highly complex, and their integration is often broadly underestimated by new engineers entering the PT field. The software connects all the subsystems and device parts in a functioning and cohesive totality which goal is to treat patients quickly and effectively. Although conventional radiation therapy (RT) is developmentally more mature than PT, their workflows are similar.

Proton Therapy Software

Workflows are alike

So it is interesting to take a closer look at the workflow perspective. Workflows tend to be quite alike in conventional radiation therapy and particle therapy. However, when you today enter a PT or RT facility, you can see a significant difference in control room design between the two types of radiation therapy. Why is there this contrast, and what can developers of PT systems learn from it? T. Rockwell (“Rock”) Mackie tries to answer this and give his opinion on other matters, too.

Rock sees the fundamental problem deriving from the integration of various subsystems into a complete particle therapy device. What is, in essence being done is adding a control system onto a control system and then joining the latter to another control system. A human has then to interact with all the mentioned control systems, and a person can only “look at one monitor at a time”.

Integrated conventional radiation therapy systems have no more than two monitors, one for interacting with the control aspects, such as patient and actions selection and image display. In fact, as Rock underlines, the image display should also include just a conventional camera display. Even regarding the patient, one can only look at one thing at once – and that is often good.  Some assume that if there are several therapists present, each one of them could be looking at a different aspect regarding the patient’s treatment.

Good workflow organisation is like driving a car

Rock believes, to the contrary, that everyone should be engaged in looking nearly at the same thing that’s relevant at that instant in time. He compares this to operating an automobile. The latter is a good example of a well-known workflow in which an individual performs tasks one at a time, such as looking at the approaching, occasionally checking different views, glancing into the rear-view mirror and the side mirrors. Nevertheless, inherently the attention of the operator is on one thing at a time. With PT, the goal would be to design systems that innately treat the therapists as individuals who give their full attention to consecutive single tasks.

The other fundamental problem with proton radiation systems is that they are – regarding at least workflow management and even treatment planning – still treated as if they were fundamentally different from conventional X-ray radiation therapy modality.

The blessing and damnation of the Bragg Peak

Rock says it all revolves around the fact that in proton therapy, the Bragg peak is where the very high dose (concentration of energy) is deposited in tissue. He warns that in many cases, we are still not able to position the Bragg peak with the accuracy that would allow us to perform more conventional treatment planning.

To solve some of the problems in proton radiation therapy, he says, we need to think of the holistic picture. We should determine how we can use effectively this high-resolution structure called the Bragg peak – and not just brag about it.

There are absolutely ways to improve PT. We have to start with full integration and avoid having disparate control systems trying to communicate and coordinate with each other. We have to plan outstanding architecture and simultaneously have good unit-based software control. We should also not forget about fully integrated software control. In the end, it will take some art, some science, and a huge focus on architecture.

At the same time, Rock sees promising developments, such as Proton VDA’s proton radiography system (pRAD)  set up at the Northwestern Medicine Chicago Proton Center. People from the centre have shown that you can control the right Bragg peak within a millimetre based on proton radiography for the brain, head, neck, and thorax.

If you’d rather listen to the above, watch the video clip from the round table:

Read the rest of the series …

This is the second article in a series of blogs dealing with the challenges of developing good software for particle therapy systems and is based on the PTCOG 59 round table “SOFTware: the HARD part of proton therapy“.


Jay Flanz, PhD, served as Assoc. Prof. at the Harvard Medical School and Technical Director at the Francis H. Burr Proton Therapy Center of the Massachusetts General Hospital before retiring in 2020.  Before that, he was Principal Research Scientist at MIT.  At the former, he contributed to the design and optimisation of the proton therapy (PT) equipment and its adaptation to clinical uses. A central focus for Dr Flanz is upgrading the beam delivery modality for optimal patient treatments.  He is the President of the Particle Therapy CoOperative Group (PTCOG) international organisation.

Zuofeng Li, PhD, is the chief physicist of the Meizhong Jiahe Medical Group (Concord Medical Holdings) and Guangzhou Concord Cancer Center. He is also a Fellow of the American Association of Physicists in Medicine, a Prof. at the University of Florida College of Medicine and was a Member of the steering committee of PTCOG. Dr Li has more than ten years of experience, specialising in radiation physics, brachytherapy, image-based brachytherapy, combined IMRT and brachytherapy delivery.

Thomas Rockwell (“Rock”) Mackie, PhD is Emeritus Prof. in Medical Physics, Human Oncology, and Engineering Physics at the University of Wisconsin-Madison and the Director of Medical Devices Focus Area at the Morgridge Institute for Research. He is a medical physicist that also developed a safer type of radiation therapy called tomotherapy, which produces less radiation without lowered effectiveness and is the marriage of a linac and a CT scanner. Dr Mackie is also focused on the development of a compact proton therapy device.

Uros Mitrovic, PhD, is a technical expert with more than ten years of experience in several medical fields, including radiation therapy and medical imaging. He holds a PhD in medical image processing and is the author or co-author of several papers in prestigious journals, conference proceedings and US patents. At Cosylab, Uros is the Medical Product Portfolio Manager of OncologyOne product suite.

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