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