STP Specialisms | Imaging with Ionising Radiation

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Ionising radiation. For lots of people, those words bring up images of glowing green goo, Chernobyl, and Godzilla.

But, for IIR specialism trainees (or imaging physicists) , those words mean another day at the office! Imaging physicists work across Nuclear Medicine and Diagnostic Radiology to help clinicians obtain the best possible patient images to inform their diagnosis and care. Although the two disciplines form the images in very different ways, the commonalities between them lead to an incredibly varied and busy specialism.

If you’ve finished rotating through all four flavours of Medical Physics (Imaging with Ionising Radiation, Imaging with Non-Ionising Radiation, Radiotherapy and Radiation Safety) and you’re wondering if Imaging with Ionising Radiation is for you, or you’re thinking of applying but you wonder what on earth you’d be doing as “Medical Physics – Unspecified”, this is the place for you.

What is IIR?

Imaging with Ionising Radiation is a specialism dedicated to obtaining optimised patient images using either radionuclide tracers or an external X-ray beam. Patients present to imaging departments for a huge range of investigations – in any one day in your local radiology department you could see CT cardiography (to investigate cardiac symptoms), chest X-rays (commonly used for assessment of pneumonia or more recently, covid-19), or barium fluoroscopy (which studies the function of the digestive tract) to name a few. In Nuclear Medicine, patients could be booked in for a cardiac scan to assess ischaemia prior to stenting, a bone scan to monitor infection or detect metastatic tumours, or a renogram which looks at the function of the kidneys to check for blockages or kidney disease. This specialism covers all areas of the body and the function of many of the body’s systems.

IIR is split over two main modalities, Diagnostic Radiology (X-ray imaging) and Nuclear Medicine (which uses radioactive tracers). Each area has multiple different subsets to get to know. Diagnostic radiology has varied equipment to test such as fluoroscopy, CT, dental X-ray and  mammography units which give really  detailed anatomical information. Nuclear medicine  covers areas such as  diagnostic and therapeutic NM, and non-imaging NM tests such as kidney function tests or red cell mass determination. Nuclear medicine scans often are used to assess physiological function by imaging where in the body the radioactive tracers are taken up.  

Shown above is a hybrid scanner that covers both modalities, a SPECT/CT scanner which can produce both X-ray and Nuclear Medicine images. An example hybrid scan is shown below, which really illustrates how functional information can be overlaid on an anatomical image.

Left: Nuclear medicine image, middle: CT image, right: fused image showing both tracer uptake and anatomy.

In either modality as an imaging physicist, your main responsibilities include:

  • Quality control of equipment which can include X-ray units, gamma cameras and radiation monitors
  • Keeping your department compliant with the various sets of regulations governing work with ionising radiation which includes maintaining:
    • Radiation risk assessments (to keep the Health and Safety Executive happy under IRR17) which aim to protect members of staff and the public by keeping their doses below legal limits
    • Employer’s procedures (to keep Care Quality Commission inspectors happy under IR(ME)R17) which set out and focus on optimising the patient’s radiation dose
    • Additionally in Nuclear Medicine, keeping radioactive waste logs and source records (to keep Environment Agency inspectors happy under the EPR16) to ensure that everything radioactive is stored and tracked correctly according to the amount of radioactivity we can have at any one time
  • Being a friendly science-y face around the place to troubleshoot issues with equipment and give advice on topics such as radiation protection, or radiation dose calculation.

On top of all of that, we try to improve our service wherever we can by performing audits, both of patient doses and image quality, and carrying out research into ways we can optimise medical imaging at our centre.

That’s enough to keep you busy throughout the specialism, but I promise there is usually time for a tea break!

Over the specialism you often feel more naturally drawn to one of the two areas, but one of the advantages of this specialism is that it’s still quite broad so you’re able to get a feel for two relatively different imaging modalities across the specialism competencies. Both areas also involve quite a lot of radiation protection work as part of the job, so you’ll often have contact with physics colleagues in the Radiation Safety team.

Clinical Involvement

One of the main draws to IIR in my opinion is the level of patient interaction available to you in this specialism. Medical physics can sometimes (unfairly) have a reputation of “those geeks in the basement” who get stuck in an office ages away from the clinical floor – in IIR and Nuclear Medicine especially, you’re right in the middle of the action.

In many centres Nuclear Medicine physicists are involved with, or lead, the administration of radionuclide therapies to patients. This involves administering the patient with a radionuclide-labelled drug (e.g. Lutetium-177 PSMA to treat prostate cancer) to systemically treat conditions. This is often to treat cancers, but it is also used for other benign indications as well such as using Iodine-131 to treat hyperthyroidism, so you can often find an IIR clinical scientist hovering nearby with a radiation monitor (an example monitor is shown below), or talking the patient through radiation protection principles.

This was in fact what drew me to the STP in the first place – work shadowing a physicist and watching them administer an Iodine-131 therapy to a thyroid cancer patient.

I-131 is selectively taken up by thyroid cells, and so this therapy is used to “mop up” any errant thyroid cancer cells post-thyroidectomy, which reduces recurrence rates and boosts survival. It’s not just my colleagues in radiotherapy that can lay claim to treating cancer as part of their normal routine – and in my opinion it’s one of the most rewarding aspects of my job.

Summing up

If nothing else, I hope that this post has convinced you that there are cases where ionising radiation can be used to help people and get to the bottom of diagnostic questions, it’s not all glowing green goo. The fundamental goal of this specialism is to train you to be able to maximise the information obtained from both anatomical and functional data from patient images.

As with all STP specialisms, there is an awful lot to learn crammed into the programme – further exacerbated by the combination of X-ray and Nuclear Medicine disciplines. However, if you’re up for the challenge this specialism gives you the tools to make a real difference to patient care.

Author: vlindsay

I'm a 3rd year STP specialising in Imaging with Ionising Radiation at University Hospitals Sussex Trust, based in Brighton.

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