Lucas van Vliet

‘Good proton therapy means that you have less likelihood of damaging surrounding tissue.’



Lucas van Vliet obtained his doctorate in 1993 on computational methods for quantitative imaging. After guest research posts in the US and a personal grant from the Royal Netherlands Academy of Arts and Sciences (KNAW), he was appointed full professor at TU Delft with an academic assignment for multi-dimensional image analysis. He was given a double appointment at the University of Leiden in 2012 at the Faculty of Science. At the present time he is head of the department of Imaging Physics (TU Delft), chairman of the Delft Health Initiative and chairman of Medical Delta’s Programme Council.


TU Delft: Imaging Science and Technology, Head of the department
Leiden University - Faculty of Science


Chairman of the Medical Delta Programme Committee

First proton therapy clinic

Treatment first patients in 2016

‘We hope to be able to welcome the first patients here in Delft in 2016. The minister has issued four licences; for clinics in Groningen, Maastricht and Amsterdam – but we will realise the first clinic of the Netherlands here in Delft, in the Medical Delta.’

‘About half of the patients who now receive radiotherapy – classic radiotherapy whereby tumours are bombarded with high-energy photons – receive it as curative treatment, in order to be cured. The other half of the treatment is palliative, which means the goal is to limit or to ease the suffering. Studies show that you can help a third of the curative patients more effectively with proton therapy compared to the advanced radiotherapy as used today.’

Treating tumours in problematic areas

‘The benefit of proton therapy is suited to treat tumours in the brain, neck, eye and prostate: tumours in problematic areas. Standard photon radiation therapy harms the tumour but also a lot of the surrounding tissue. Radiation can cause impeded growth deformities or permanent damage to vital organs. Good proton therapy means that you have a far smaller likelihood of damaging surrounding tissue.’

Protons versus photons

‘What I mean by good proton thera- py is that you ensure that the proton beams are properly targeted at the tumour tissue, and deposit their en- ergy there. In this respect, protons have one major advantage over photons: photons release most of their energy in the surrounding tissue, en route to the tumour, as it were. And some of the energy passes the tumour and reaches the tissue behind it. Protons do release some of their energy on the way to the tumour, but most is released at the target. So you can give them the exact amount of energy they need to penetrate the tumour and release the energy there, damaging the tumour cell to such an extent that it dies off.’

‘By controlling the direction of the beams and the speed of the protons you can target different areas of the tumour until you have irradiated the entire tumour, while avoiding surrounding organs that you really don’t want to affect. In the case of prostate cancer, for ex- ample, you have to avoid damaging the rectum, which is very close by. If that happens, you create a patient rather than cure one.’

Combination of a clinic and an R&D centre

‘HollandPTC is going to be a combination of a clinic and an R&D centre. Clinic and research facilities should be in close proximity. The proton beam will of course be used mostly for the treatment of patients; you have to use the time that is left over for research – and if you want to do that effectively, you need to be at hand.’

‘A full course of treatment typically consists of between twenty and thirty separate sessions. At first, we want to make use of ‘adaptive radi- otherapy’, whereby the treatment plan per session is modified on the basis of the day-to-day change in patient anatomy as revealed by a 3D scan. Obviously what you want to see most of all is shrinkage of the tumour, but this also allows you to compensate for a shift in the location of the tumour caused, for example, by day-to-day differences in the contents of the bladder or the intestines.’

Detecting gamma radiation

‘But the ‘Holy Grail’ is to image the dose deposition in real time and to redirect the beam if necessary. Then you have to be able to ‘see’ precisely how far the beam is penetrating. At the moment that the protons stream towards the tumour, they interact with atoms, and this produces gamma radiation. We can detect this radiation. This ‘trail’ of gamma radiation allows us to see exactly where the protons release their energy. We can use this information to check if the beam delivers its energy at the correct lo- cation and it will allow us to modify the proton energy and the direction of the beam in real time.’

‘This development means that certain tumours that are at present very difficult to treat may be considered for proton therapy. For example, tumours that move continually, due to the movement of the heart, arteries or breathing. We will have equipment that ‘breathes’ in tandem with the patient.’

Concentration of clinical and technical expertise

‘Medical Delta is an excellent concentration of clinical and technical expertise. And, even though no one is as yet being treated in the soon to be opened proton therapy clinic, we still can’t do without the input of clinicians for our research. We need to know what they want and what their demands are regarding the treatment plan, so that we know what instruments we should be developing.’