What sparked your initial interest in physics?

As a child I was fascinated by biology and aspects of physics such as electricity and magnetism. I was very lucky that my physics lessons at school were taught by a very enthusiastic teacher, who stimulated my interest strongly. I was especially interested in nuclear physics.

What area was your physics degree in, and did you ever consider a permanent academic career?

As I preferred applied physics over theoretical physics, I chose to study the former at the Delft University of Technology. I did my MSc in radiation physics at the Reactor Institute Delft, which is a research institute, not a power plant. I worked at the institute as a research scientist for a few years after finishing my degree. After a while, I switched to working as a medical physicist – first at the Radiotherapeutic Institute RISO, and later in the radiology and nuclear-medicine departments at the Deventer Hospital in the Netherlands – for more than 30 years of my career. In that time, I published some papers and completed a PhD at the University of Utrecht, on treatment of prostatic cancer using I-125 seeds.

How did your interest in photography emerge?

In the late 1990s, while teaching radiation physics and radiation safety to radiographers and physicians as part of the hospital’s programme, I found that even very thin objects (such as flowers) can be imaged when using very low energy X-rays. After a few years, I started to colour some of these X-ray images, and people found them interesting. I got my own licensed X-ray studio in 2007 and, after retiring from the hospital in 2012, I have been working full-time creating “bioramas” – nature scenes involving flowers, plants and animals. I was inspired by the unbelievable beauty of nature, and became aware of its wonderful complexity.

How do you create your portraits?

I set up a natural scene, and then X-ray it in one session as a whole – the images are not stacked or layered digitally. The animals I use are dead, as I dont think I could justify exposing living animals to X-rays for my art. I source the animals in different ways – I find traffic-victims along the road side, or birds who have flown into windows. The fish I buy at a market, while my cat catches the occasional mouse or mole. I also have a friend who breeds reptiles, who gives me their carcasses. I use animals as I find them – especially in the case of traffic victims, the anatomy mostly is mutilated, so you will see animal injuries in a lot of images.

And how do you do this in practice?

Once the scene is set, I position an analogue silver bromide X-ray film (in a light-tight envelope) with the biorama on it, and place it on the floor. The X-ray tube is about 100 cm above the film, which is a fine-grain (high-resolution) film, with a steep gradient (high contrast). But it has relatively low sensitivity, and so a high dose of radiation is required for sufficient optical density. First, I take a low energy 2.5-minute exposure to image the thinner parts (such as the petals or leaves) of the biorama, immediately followed by a higher-energy exposure of 3.5 minutes to image the thicker parts. The film needs a maximum total dose of about 300 milliGray, resulting in a maximum optical density of about 3. After processing the exposed film in a dark room, I judge each analogue image and measure its optical density. I digitize the X-ray image using a scanner, and edit the grey levels with Photoshop. I pick and colour some areas of the image and, often, it is inverted.

What are some of your current projects?

This year, I exhibited my 3D X-ray images at the Natural History Museum in Rotterdam – you observe the portraits through a View-Master. My photographs were also included in a recent Dutch children’s book titled Binnenstebinnen, published by Gottmer, Haarlem. I hope it gets a sequel.

How has your physics background helped?

It’s not easy creating these X-ray images where there are huge differences in thickness – from the very thin petals of a flower or the feathers of a bird, to the relatively much thicker bodies of animals. I think that my medical background in X-ray physics was of great value, and allows me to now take the perfect X-ray.

Any advice for today’s students?

You are studying during a wonderful period of great discoveries and interesting discussions in physics – enjoy it!

• Arie van ’t Riet’s images are available from Science Photo Library

• Enjoy the rest of the June 2018 issue of Physics World in our digital magazine or via the Physics World app for any iOS or Android smartphone or tablet. Membership of the Institute of Physics required