At 23, Gonçalo Ribeiro is already navigating two worlds: the academic institutes of physics and the fast-moving arena of entrepreneurship. What began as a ‘crazy idea’ during his bachelor thesis, proposed by his supervisor Pedro Assis, is now a patented innovation that could make certain cancer treatments up to a hundred times faster.
Ribeiro coined his start-up that is working on this innovation FLASHGuard, and it aims to revolutionize beam monitoring for radiotherapies.
It is to his own surprise that the idea worked. Now, only a few days after he has handed in his master thesis, Ribeiro is preparing to pitch FLASHGuard at the SME assembly in Copenhagen.
Unbeknownst to him at the point of this interview, is that he would be crowned the winner of the Youth-Start Up competition 2025, not even 24 hours later. Despite his busy schedule, Ribeiro supervises a team of five students alongside his supervisor who first sparked the project.
At 23, Gonçalo Ribeiro is already navigating two worlds: the academic institutes of physics and the fast-moving arena of entrepreneurship. What began as a ‘crazy idea’ during his bachelor thesis, proposed by his supervisor Pedro Assis, is now a patented innovation that could make certain cancer treatments up to a hundred times faster.
Ribeiro coined his start-up that is working on this innovation FLASHGuard, and it aims to revolutionize beam monitoring for radiotherapies.
It is to his own surprise that the idea worked. Now, only a few days after he has handed in his master thesis, Ribeiro is preparing to pitch FLASHGuard at the SME assembly in Copenhagen.
Unbeknownst to him at the point of this interview, is that he would be crowned the winner of the Youth-Start Up competition 2025, not even 24 hours later. Despite his busy schedule, Ribeiro supervises a team of five students alongside his supervisor who first sparked the project.
“We are training the researchers, entrepreneurs, and the future as well,’ he says proudly, continuing the cycle of mentorship that shaped his own innovation.
While the physics of the FLASHGuard may be elusive for non-experts, its benefits are easy to grasp: quicker, safer, and more effective cancer treatments. But why is it regarded as one of Europe’s most promising start-ups? And how did a 23-year-old bring it to life
Faster cancer treatments
The background of FLASHGuard traces back to 2014, when a French innovation called FLASH therapy discovered that if you deliver radiation to a patient in less than a second, you could spare healthy tissue. Unfortunately, in conventional treatments – which can last up to several minutes – patients still accumulate radio-induced toxicity.
“It’s particularly dramatic for children. Even if they have high chances of surviving cancer due to treatment, they can have secondary cancer because of the radiation,” Ribeiro explains.
A shorter exposure time to radiation is a propitious method to diminish the side-effects of cancer treatment. Specifically this FLASH therapy would be up to a hundred times as fast as regular radiotherapy. And it would be a great stress-relief to our healthcare systems: “Instead of going to the hospital multiple times, patients would only go once,” theorises Ribeiro.
It’s important to acknowledge that the idea of a one-time treatment is still only hope, not an established reality. The literature suggests that it may be possible, Ribeiro notes, with current research typically referring to one to five treatments.
Yet the possibility of reducing radiation time could transform treatment for the 50% of cancer patients who currently endure up to 25 radiotherapy sessions. Every year, roughly 10 million new radiotherapy treatments are administered. With less harmful beam monitoring, these patients could receive safer care.
The physics behind FLASHGuard
The benefits seem to be huge in this field. As a physicist, Ribeiro and his team are focusing on developing a technology that makes these faster treatments possible – a technology that can monitor the beam.
“We are talking about treatments that are 100 times faster. Current systems cannot cope with this. We need to ensure that the patient is receiving the radiation which was programmed, and for that we need a 100 times faster device than the one that exists now, to ensure patient safety. This is called beam monitoring. You literally monitor the beam during treatment,” Ribeiro explains.
In an attempt to explain the physics behind the beam monitoring technology simply, Ribeiro uses the analogy of ducks gliding across water and creating a V-shaped pattern behind them.
There is a similar effect in physics. When a particle moves through a material, it can sometimes travel faster than light moves through that same material. He emphasises that it does not violate Einstein’s principle, as the speed of light in water is lower than the speed of light in a vacuum.
When a particle exceeds the speed of light, it emits a tiny, instantaneous flash of light. If you build detectors fast enough to capture these flashes, you can monitor the particle beam at the same speed as particles are moving. In other words – it becomes very accurate.
How such a detector is built, remains elusive. ‘Don’t focus on the features of the system, please,” Ribeiro urges. It’s bad practice, he thinks, as the scientific article that explains his mechanism is not published yet.
At it’s core, FLASHGuard is thus a monitoring system built on a simple insight: the amount of light produced in a radiotherapy beam is directly proportional to the number of particles in it. In theory, this makes it easier to monitor dose delivery – something other systems are failing to do accurately.
Those current detectors still saturate and stop being linear at high dose rates. The risk is that you might give the patient more radiation than planned, and the system will not let the alarm bells go off. With FLASHGuard, the beam monitoring can be much more effective and therefore reduce the risk of oversaturation in radiotherapy.
Patented innovation
At only 23, and in the early stages of his physics career, Ribeiro has already patented an innovation that eludes others in the field. When asked if he thinks his youth gives him an advantage in thinking innovatively, he favours attributing the success to knowing his supervisors Pedro Assis and Professor Patricia Goncalves.
“Obviously, someone else could be doing this as of now. It would be something extraordinary if you were the only one to think of this. And sometimes you have to be humble. That’s our approach to this,” he explains.
Even though he patented it months ago, Ribeiro can never be completely sure that someone didn’t submit a patent a day before him. Out of the facial expressions Ribeiro is making, it is clear to see that he is nervous about that thought. Yet, when the question over anxiety having the idea first is raised, he is quick to correct the assumption.
“When you commit to something, I think that there will always be an imposter syndrome saying, why are you doing this?,” he reflects. Instead of the patent, this year he has been mostly focusing on building a team to get funding. In his eyes, that is the method to create a successful start-up.
“I would emphasise this as something crucial for a successful project: surrounding yourself with highly competent people,” he stresses.
With all the conferences he has been attending, it still seems that nobody has patented this before. And even if it turns out that way, Ribeiro calls it a fair game:
“You just have to work with them, because we are working towards the same goal. As long as this project works, it would be amazing.
Philosophy as an entrepreneur
His philosophy as an entrepreneur reflects this collaborative mindset. With a technical background, he believes to have an advantage compared with other profiles.
“We are used to having a problem and decomposing that problem. Decompose it into small pieces. We have a rational way of thinking,” Ribeiro says.
The main drawback of having this background is simultaneously this rational way of thinking – it is perhaps not a good idea when dealing with people. Still, his approach to his own team is reflective of a human-centered ideology.
“We are more interested in having good researchers than someone just working on a project. We are also more interested in providing a strong background, because people will like working then. People will be loyal to you, because you are helpful to them. You were not interested in using them. You were interested in providing them with conditions to flourish in an environment.”
In a similar vein, Ribeiro’s own supervisor gave him the trust,the first seeds of the idea for FLASHGuard, and the opportunity to work those seeds out into his PhD. As Ribeiro keeps stressing during the entire interview – “We should acknowledge him more.”
FLASHGuard is a testimony to what can happen when young researchers are trusted with their ideas. In Ribeiro’s summarising note, that is also the project’s most important takeaway and the core of his motivation – not the money, but to make researchers, entrepreneurs, and people grow and learn.
In 2026 FLASHguard will be taken to the European Innovation Summit in Brussels. It is funded by “La Caixa” Foundation, F.C.T., I.P. and the research center LIP.
