Last year there was a horrible radiation overdose in California, where a CT technologist gave a 23 month old child 151 scans in just over an hour. A hearing to revoke the tech’s license is just underway and the testimony so far gives little indication exactly how it happened.
The article from auntminnie.com gives this chilling testimony from the boy’s father:
In testimony before an administrative law judge, the boy’s father, who during the scans was standing at the foot of the CT table to calm his son, recalled his growing concern as the scanning stretched on. “I said, ‘Stop this!’ ” Padre Roth recalled, noting that Knickerbocker finally stopped the scan only after he became angry.
Within a few hours, the child developed a bright red ring around his head from the massive overdose of radiation. Photographs of the left side of the boy’s face show a clear line extending from the infraorbital ridge backward through the ear and nape of the neck; a similar line extends from the infraorbital ridge through the ear on the right side.
In off-the-record comments, some state officials called it the worst case of radiation overdose of a child in the U.S.
How could something like this happen? Apparently the tech involved pressed the scan button 151 times, averaging 25 seconds between each press. Afterward, she could give no satisfactory explanation for the event. She gave various excuses including motion of the patient, mechanical failure and distraction by the parents. None of these are any excuse for intentionally irradiating a patient that many times. Her supervisor could only describe it as a “rogue act of insanity”.
The consequences were dire.
A report by the hospital’s medical physicist calculated that the boy’s absorbed radiation dose was 2.8 Gy (2,800 mSv) and possibly as high as 11 Gy (11,000 mSv). The dose the boy received compares to a range of 1.5-4.0 mSv for a normal pediatric CT study of the entire spine, according to pediatric imaging experts.
Using relevant material from the article “Estimated Risks of Radiation-Induced Fatal Cancer from Pediatric CT,” published in the American Journal of Roentgenology (February 2001, Vol. 176:2, pp. 289-296), a report by the hospital’s medical physicist concluded the child had a lifetime increased risk of a fatal cancer of 39%.
Hopefully the hearing will shed more light into what exactly went wrong. There should be a written procedure in place on how to respond to instances where the CT scanner behaves incorrectly. Often, however, scans like this are seen to be too routine to worry with a formal procedure. Technicians are expected to be able to adapt to unexpected events. If the technician does not have the necessary understanding of the system, though, the consequences can be catastrophic. In his book The Human Factor, Kim Vicente describes how a lack of understanding caused the Chernobyl accident.
The problem was that the plant designers hadn’t paid enough attention to the human factor – the operators were trained but the complexity of the reactor and the control panels nevertheless outstripped their ability to grasp what they were seeing. [The reactor operator] didn’t completely understand the effects his actions were going to have until it was too late – with devastating consequences.
As a friend of mine once told me, “the secret to life is being smarter than the machines you work with.”
Undoubtedly, the technician in this case will have her license revoked, and rightfully so. The fact that a scan that should have taken a few minutes instead took more than an hour was a warning sign that any reasonable person should have heeded. However, that won’t make the problem go away. If the CT console software is too complex for a trained technician to understand, then the software needs to be simplified or there need to be hard and fast guidelines as to when someone with a greater understanding needs to be called in.
