6 months in radiation safety

Disclaimer: in the ensuing rant all opinions expressed are mine and mine alone.  I don’t confess to having the answers, only many, many questions. My STP experiences should not be taken as general.  

The last 6 months have been tough for me.  After the highs of MR and radiotherapy, I found myself in a work culture that at times didn’t seem to value independence or innovation.  I don’t wish to dwell, especially given that, in the end, I did get signed off on all my rotational competencies and assessments.  

Let’s, rather aptly, get back to the matter of radiation safety by musing over a risk assessment.  What are the hazards associated with the medical use of ionising radiation?  

You can die immediately as a consequence of ionising radiation exposure.  As an example, as an incidence of gross over-exposure I reference the case of a 34-year experienced radiation worker, working in a sterilization facility, who received an estimated whole-body effective dose of the order of 20Sv within a few minutes.  This individual found themselves in the radiation-controlled area with the source in the irradiate position.  Despite prompt medical care, the man died 113 days later.  The clinical details are harrowing; as is the catalogue of procedural errors that lead to the incident.  You can read all about the incident in this fascinating IEAE report.   

We know that above certain levels, but below those of the incident described above, the acute effects of radiation exposure include nausea, vomiting, hair loss and skin burns. These are described as deterministic effects because we know that if you get this much radiation, we expect you to develop these symptoms.  

But let us not forget that we are in a hospital.  We deliver ionising radiation as therapies.  There will be a patient in the beam.  So, we can comfortably drop-kick this kind of gross exposure concerns into the long grass.

What about chronic low-level exposure, such as those that may befall a hospital worker involved in the administration of ionising radiation for therapeutic or diagnostic purposes; think medical X-rays, CT scans and handling radioisotopes?  

The framework for radiation safety stems from the data that we have from incidents of gross population exposure such as Hiroshima and Chernobyl.  We know that these high levels of exposure are correlated with an increase in cancer incidences among the exposed population.  Radiation safety physics draws a straight line back from this high exposure data in order to formulate an estimate of the risk that arises from low-level exposure to ionising radiation.  

There are, in my opinion, several issues with this.  

One, low-level ionising radiation exposure is a fact of life.  Sources of ionising radiation include the small fraction of naturally radioactive potassium in the banana you ate for breakfast, high energy cosmic rays from outer space as you flew long-haul and radium gas in the ground that accumulates in buildings and basements over time.  There’s no evidence to suggest that humans are not in some way built for low-level ionising radiation exposure.  Indeed, wouldn’t it be naïve to assume otherwise given the few millenniums of successful evolution are on our side?  

And the second, bigger, issue is the noise level.  It is now estimated that 50% of people born after 1960 will develop cancer over the course of their adult life.  Perhaps this is a natural consequence of longer life expectancies, more advanced imaging and methods of detection.  Or is it a product of chronic stress exposure, poor sleeping habits and nutritionally poor but convenience rich diets?  

I don’t have the answer to that one, and the issue is clouded by stochasticity.  We can identify risk factors, but we are still shackled by probability.  There will, desperately sad thou it is, be people who do everything by moderation, just as the Doctor ordered, but still get sick.  

I guess the crux of the issue is that it is very hard to sell the health detriments of low-level exposure to ionising radiation to a trainee who regularly sees, and believes passionately in, the therapeutic benefit of ionising radiation.  Radiotherapy works and is indeed sometimes a victim of its own success.  But that is a topic for another blog post.  

The above is not to say that I don’t buy into the ALARP (risks – as low as reasonably practicable) principle.  Nobody should get sick as a consequence of their occupation, the 1974 Health and Safety at Work Act is a triumph for a progressive society.  And right on cue, below sits evidence of me rehearsing a technetium radiopharmaceutical (water!) spill.  I am privileged to have had a thorough and practical discussion on how to deal with such incidents efficiently, keeping my own exposure to a minimum.  The learning experience reinforced to me that the greatest weapon in the arsenal against exposure to ionising radiation is staff training.  

There is, in my opinion, a far more important duty of a healthcare physicist.  

I was fortunate to be referred for an elective interventional radiology procedure at Colchester during my time there.  I had a problem with my vasculature and the plan was for the consultant to go in, via a small incision in my neck, inserting coils into the problematic veins to relieve the pressure.  It was strangely humbling and fascinating to be on the other side of the lead glass. But the thing that touched me the most about this experience was the care and attention to detail that every member of staff involved in my care pathway demonstrated.  The day unit nursing staff, the radiographer delivering the fluoroscopic X-rays and the consultant pushing tubes through my jugular; patient experience is so heavily dependent on the skills and demeanour of every member of that team.  The patient-facing clinical staff of the NHS are the reason why the NHS is a world-beater! 

But whilst they are busy delivering this care, they should not be thinking about machine performance parameters and tech.   

There is no denying that medical imaging has revolutionised medicine and the importance of timely and good quality imaging in care pathways cannot be overstated.  And that is just it, image quality; the beauty is in the eye of the beholder.  Reporting clinicians, interventional radiologists and oncologists make life-changing decisions based on their perception of image quality.  

So, the role of a healthcare physicist is an easy one to state, but perhaps not an easy one to deliver. The settings of your CT scanner, gamma camera, MR magnet, X-ray radiograph and obstetric ultrasound need to be verified and tuned to deliver images of maximal diagnostic value.  The key thing here is that maximal diagnostic value needs to be determined at a local level.  Blanket, one size fits all settings are not going to deliver high quality individualised patient care that is the mantra of modern medicine.  

To this end, proprietors of medical imaging hardware provide powerful software for the addition of user-end functionality and development.  In my opinion, the STP training for medical physics is desperately replete of opportunities to develop the skills and working practices that can influence service improvement at a local level.  The NHS spends a small fortune on the latest physics hardware and then fails to explore its full potential.  

And on top of all that, in the age of big data, image quality metrics, machine settings, reporting statistics and clinical protocols must be measured against appropriate endpoints and patient outcomes.  We dose patients all the time, yet the evidence for evidence-based healthcare seems not to materialise.  As future healthcare scientists, there is clearly much work to do! 

Perhaps, as a trainee, I speak above myself.  The vast majority of my experience of the rotational component of the STP programme has been overwhelmingly positive and I feel blessed to a part of it.  

Next year, it’s back to radiotherapy at Ipswich for me.  I have the privilege of undertaking my specialism in a supportive radiotherapy department that delivers world-class, life-changing patient care.  I am excited, and I relish the challenges that 2020 will bring.  

Happy New Year to all those in the NHS and in particular those involved with the STP programme, trainers and trainees.    

Author: Liam

Trainee clinical scientist at the Ipswich Hospital.

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