Dr Christina Skourou, Senior Medical Physicist at St Luke’s Radiation Oncology Network in Dublin, speaks to Dr Claire O’Connell about the ethics of ionising radiation protection in medicine and clinical trials.
From sitting in the sun to taking a flight, our bodies are often exposed to different forms of radiation in the environment. Medicine has learned to harness the benefits of certain types of radiation and utilise it as a tool to diagnose and treat many injuries and conditions. X-rays, CT and PET scans, mammograms and angiograms, all use ionising radiation to see through the body. Radiotherapy uses high energy targeted beams to destroy cells in the body without the need for a surgeon to cut through it.
In particular, ionising radiation is commonly used in medicine to diagnose and treat many injuries and conditions, including in X-rays, CT-scans and using targeted beams of radiation to treat cancer. It can also be an enormous asset for patients and clinical research.
Given that ionising radiation can potentially cause harm many years after a person is exposed to it, are we keeping track of each patient’s cumulative doses and exposures over their lifetime? Should ionising radiation be used routinely to monitor treatment response in clinical trials? And can patients truly understand the potential harms when we lack evidence around the risk of fallout from exposure, particularly in the longer term?
These are some of the tricky questions that arise in the ethics of radiation in medicine, according to Dr Christina Skourou.
Christina is a Senior Medical Physicist at St Luke’s Radiation Oncology Network in Dublin and co-author of the 2018 book Ethics for Radiation Protection in Medicine, and an advocate for informed design of clinical treatment protocols and clear communication with patients.
Minimise risks
The ionising radiation used in, for example, CT-scans and cancer treatments, can by its very nature potentially damage tissues in the body, Christina notes, but such ‘justifiable harm’ is common in medicine and surgery.
“Sometimes it is permissible to cause a harm as an unintended and merely foreseen side effect of bringing about a good result. A surgeon needs to cut the body with the intention to remove a tumour. An oncologist gives a patient toxic drugs with the intention to attack a cancer,” she says. “In radiotherapy, we deliver ionising radiation to destroy cancerous cells.”
Treatment protocols for patients try to minimise the harm by calculating the path of the radiation beam through tissue, avoiding healthy organs and targeting the maximum effect at the tumour. But the ethics become fuzzier when we look at the potential for other or longer-term harms.
“Suppose a brain tumour is likely to kill a patient in three months unless action is taken, but the radiation that can treat the tumour bears some risk of severe memory loss in five months or in ten years. Is the treatment ethical?”, asks Christina.
Watch the dose over time
In practice, many factors are taken into consideration when treating people or developing a clinical trial protocol, such as the age of the person, the severity of their diagnosis, other options for treatment (such as chemotherapy or surgery) and the overall balance of clinical needs, risks and benefits in the longer term.
“It’s important that exposure to radiation over the course of the treatment is also included in these assessments,” she says.
Diagnostic scans and X-rays use far less radiation, but multiple exposures over time could also increase the risk of harm to the patient, and we need to take the cumulative dosages into account when looking at that longer-term picture.
“If you take a medicine such as paracetamol, you can see the tablet contains 500 milligrams and you know how many of those you need for benefit and how many would result in an overdose,” she says. “When you get a scan, we tend not to talk to the patient about the specific dose of radiation they are receiving and what that means in terms of benefit or risk.” This is largely because we don’t know the specific risk to the individual from this level of exposure.
This uncertainty about the potential risk of harm is what raises many ethical questions.
“Ultimately, it needs to be the patient’s decision whether or not they accept the risk from radiation exposure. But how do you inform someone about a future harm that we can’t really describe in the present day? In these situations, a form of the precautionary principle needs to apply. This principle in a way says that in the face of uncertainty we ought to tread carefully.
Consider the protocol
In clinical trials that specifically involve radiation for treatment or for monitoring purposes, an expert in the field is typically involved and can advise on trial design. They advise on the appropriateness of the radiotherapy dose or the choice of imaging scans along with an evaluation of potential harm. But what about the trials where radiation has more of a supporting role?
Christina is particularly cautious about trial protocols that use ionising radiation, such as in CT-scans, as a way to monitor progress.
“CT is quick and cheap, but it does come at a cost, which is radiation exposure. You may have a trial where the patient gets a CT-scan every week or every month to see if a tumour is shrinking. We need to think about that – is that frequency of scanning appropriate? Is it likely the tumour will change that quickly?”
Christina highlights the time and potential anxiety cost to the patient, who could otherwise be spending time with their family, and that overusing CT-scanners in a clinical trial could mean delays for other patients who are not on the trial but are waiting for scans.
Ionising radiation is heavily regulated and radiologists are required by law to justify scans for standard treatments and clinical trials, notes Christina, and ethics have a role too.
“At ethics review we need to assess whether exposing the patient to this much radiation and inconvenience is adding value to the trial,” she says.
Patient-focused approach
Ideally, when a patient is being recruited onto a trial, the research team needs to clearly communicate the role, dose and impact of the radiation involved, according to Christina.
“If a patient is going to have additional radiation exposure on the trial protocol, the team needs to respect the patient and tell them what the justification is for this, and how the study design is minimising the potential harm,” she says.
“The patient needs to understand the context – so perhaps telling them that this is double the radiation they would have if they were not on the trial, and what measures are being taken to optimise the use and minimise the harm of that.”
This is particularly important as patients generally tend to equate more scans with better care.
Christina says: “If I asked any patient in a waiting room if they wanted more scans, they would probably say yes. The thinking is that the more data the doctors have, the better they can treat me. Patients need a full picture of how much radiation is involved, how that adds value to their care, and what we understand and don’t understand about the risk. And if they say no to it, we respect that. This is the very core of ethics, enabling patients to give their informed consent and make a self-determined choice based on all the information they receive.”