About six months ago, I applied my usual brand of not-so-Respectful Insolence to what I termed unforgivable medical errors. These are errors that are so obviously harmful and lethal that there is no excuse for not putting systems into place to prevent them or so egregiously careless that there is, quite simply, no excuse for them to occur. As I mentioned before, there are a handful of such “unforgivable” errors in surgery. Although not all surgeons would necessarily agree on the specific identities of all of them, there are some upon which nearly all surgeons would agree. Examples such as removing the wrong organ, removing the wrong breast, or amputating the wrong limb come to mind. Such errors, although relatively uncommon, are so horrific that even one occurrence is arguably unacceptable.
The last time I discussed such medical errors, it was in the context of the increasing amount of medical radiation that patients are being exposed to. Given that virtually every single one of us is a patient or will be a patient at some time. No matter how young or how healthy you might think that you are, the odds are that some day you’ll be on the receiving end of some medical radiation for some test or another. It might be for trauma or an injury, where you need a CT scan or some other test. It might be that you suffer some chest pain and undergo coronary angiography. Or, you might have a severe headache or other neurological symptom and need a head CT–or even a CT brain perfusion scan. You might be like Alain Reyes, whose injury begins a story in Saturday’s New York Times entitled After Stroke Scans, Patients Face Serious Health Risks:
When Alain Reyes’s hair suddenly fell out in a freakish band circling his head, he was not the only one worried about his health. His co-workers at a shipping company avoided him, and his boss sent him home, fearing he had a contagious disease.
Only later would Mr. Reyes learn what had caused him so much physical and emotional grief: he had received a radiation overdose during a test for a stroke at a hospital in Glendale, Calif.
Here’s a hint. Whenever you see hair fall out in such a perfectly symmetrical band, look for an iatrogenic cause. The pattern of this hair loss almost perfectly lined up with how a CT scanner lines up around the head. In any case, one question about this entire incident is: How could such a screw-up have happened? Another question is: How pervasive was this error? The answer to the latter question is, unfortunately, way too prevalent: Thirty-seven at Providence Saint Joseph Medical Center in Burbank, 269 at Cedars-Sinai Medical Center in Los Angeles; and dozens at a hospital in Huntsville, Alabama. Overall, there are at least 400 such patients at eight hospitals, but, worse, it’s expected that there will be a lot more cases discovered as investigators look more closely into the radiation overdoses.
Part of the problem is that CT brain perfusion scans use a lot of radiation even when performed properly. Basically, the scan quantitatively evaluates blood flow in the brain by generating a map of cerebral blood flow, cerebral blood volume, and mean transit time. After the scan, the scanner’s software employs complex deconvolution algorithms to produce the perfusion maps. These maps look like this:
The last time I wrote about radiation overdoses from medical radiation, the problem occurred during radiation oncology treatments for cancer. When treating patients for cancer, one might argue that it is acceptable to take a bit more of a risk than one might for diagnostic imaging because actual therapy is being administered. While it’s true that a proper diagnosis can be a matter of life or death, in general less risk is acceptable when it comes to medical imaging for treatment.
We know the scope of the problem is huge, but how did it happen in the first place? To examine the NYT story is to see everyone pointing fingers at everyone else. Basically, in general the more radiation a CT scanner uses the better quality the image. The problem, of course, is that it’s very easy to use more radiation, but over the last decade the medical community has come to appreciate that the cumulative effect of all the various sources of medical radiation to which patients are subjected can pose real risks. Becuase of that, the GE scanner used in these cases has a built-in capability of automatically adjusting the dose according to the patient’s size and to the part of the body being scanned. According to GE, it’s a technical feature designed to reduce radiation dose.
However, there is a problem, and it turned out to be a big problem. The automatic feature behaved in a counterintuitive fashion under some conditions using certain settings governing image clarity. Instead of decreasing the amount of radiation used, the machine increased it. In some cases, it increased the radiation dose to as much as eight times as much as what it should have been. Unfortunately, neither the CT scan techs nor the radiologists who oversaw them appeared to be aware of this aspect of the machine’s behavior. And so the finger-pointing began:
GE says the hospitals should have known how to safely use the automatic feature. Besides, GE said, the feature had “limited utility” for a perfusion scan because the test targets one specific area of the brain, rather than body parts of varying thickness. In addition, experts say high-clarity images are not needed to track blood flow in the brain.
GE further faulted hospital technologists for failing to notice dosing levels on their treatment screens.
But representatives of both hospitals said GE trainers never fully explained the automatic feature.
In a statement, Cedars-Sinai said that during multiple training visits, GE never mentioned the “counterintuitive” nature of a feature that promises to lower radiation but ends up raising it. The hospital also said user manuals never pointed out that the automatic feature was of limited value for perfusion scans.
A better-designed CT scanner, safety experts say, might have prevented the overdoses by alerting operators, or simply shutting down, when doses reached dangerous levels.
Does this sound familiar? It should. Lack of stronger safety features permitting radiation dosages far beyond what is considered safe was the same problem in the equipment that delivered serious overdoses to cancer patients, as reported in January. If you’ll recall, the software in that case required that three essential programming instructions be saved in sequence, first the dosage, then a digital image of the treatment area, and then instructions to guide the multileaf collimator that that controlled the dose. When the computer repeatedly crashed, the medical physicist didn’t realize that the instructions to the collimator hadn’t been saved. In both cases, there was no fail safe mechanism to shut the machine off before it administered too high a dose of radiation.
I don’t know about you, but personally I find it shocking that modern equipment could be designed with such lax safety features, but it would appear to be a common problem in devices that deliver large amounts of medical radiation. In the case of machines designed to deliver radiation in order to treat cancer, the margin for error is lower because the intended dose is higher to begin with, but this case shows that it isn’t just therapeutic radiation can result in an unacceptable risk of harm, and it’s not just a cumulative dosage of diagnostic radiation that can cause harm. The radiation requirements of some diagnostic radiology tests have gotten so high that for them the margin of error is less than what it should be.
I also have to wonder if an excessively complex user interface contributed to the errors in Alabama and California that led to the bald ring around patients heads. For tests that can administer an excessive dose of radiation that can result in complications such as hair loss or worse, I will once again emphasize that there has to be some sort of fail safe, drop dead, impossible-to-ignore warning that forces the operator to approve the dose at least twice before permitting the dose to be given. In addition, someone should be recording the does of radiation. Believe it or not, the hospital in Huntsville, Alabama didn’t routinely do so:
Huntsville Hospital officials said they did not routinely record radiation dose levels before 2009. Mr. Ingram, the spokesman, said the hospital did keep information needed to calculate the dose, but he declined to say whether officials had gone back to determine doses for all patients who had brain perfusion scans.
The form letter Huntsville sent to overdose patients appears to play down the damage that high doses can inflict. The hospital told patients that hair loss and skin redness might occur but would go away. “At this time, we have no recommendations for you to have any follow-up treatment,” the letter said.
In actuality, the risks of excessive radiation to the brain include injury to the eyes (for example, cataracts), cancer, and brain damage. Remember, this is not cell phone radiation, whose almost certainly nonexistent or minimal risk so many people are exaggerating. It is real, ionizing radiation on the order of doses of up to 4 Gy, which is an astonishing dose for a diagnostic test. Typically for breast cancer, we treat women with 50-60 Gy total over the course of 30 to 35 fractions of less than 2 Gy each. The dose some people received was on the order of two full dose fractions for breast cancer. This is hundreds of times the dose due to most “simpler’ diagnostic imaging studies, such as chest X-rays and mammography. Depressingly, the FDA has to write something like this in its report:
FDA encourages every facility performing CT imaging to review its CT protocols and be aware of the dose indices normally displayed on the control panel. These indices include the volume computed tomography dose index (abbreviated CTDIvol, in units of “milligray” or “mGy”) and the dose-length product (DLP, in units of “milligray-centimeter” or “mGy-cm”).
For each protocol selected, and before scanning the patient, carefully monitor the dose indices displayed on the control panel. To prevent accidental overexposure, make sure that the values displayed reasonably correspond to the doses normally associated with the protocol. Confirm this again after the patient has been scanned.
Which should be routine and something the machine makes very easy.
The problem of radiation overdoses and excessive radiation from medical imaging tests can be addressed by technology. Problems of this magnitude affecting this number of patients also go far beyond simple human error. They are systemic in nature, and in this case they seem to result from a most unfortunate confluence of poor communication between equipment manufacturers, a lack of documentation of a rather important feature of the CT scanner, and apparently lax monitoring of radiation doses administered to patients in some hospitals. Because this is a systemic problem, a systemic solution is required. This solution will require input from GE, the manufacturer of the CT scanners, the FDA, and the hospitals.
However, this problem highlights once again an even more important issue in medicine. That issue is not so much how to improve the safety of tests like the cerebral perfusion scan, although that is very important. Rather, it’s determining when it is appropriate to use such powerful technology and when it is not. Reviewing the cases, there is a very real and legitimate question of whether the patients who suffered complications from radiation overdoses due to cerebral perfusion scans actually needed the scans in the first place. If there’s one medical “sin” we physicians are very prone to, it’s becoming overly enamored of the latest technology to the point where we order it at the drop of a hat. It was pointed out in the article that many of the patients who suffered radiation overdoses were relatively young, so young that the diagnosis of a stroke would normally seem to be a relatively unlikely diagnosis. Did these patients have actual neurological symptoms suggestive that they were having a stroke? Or where their symptoms equivocal? Would an “old-fashioned” CT have provided the necessary information at a much lower dose of radiation? In which patients does the potential benefit of these scans outweigh the risks?
Unfortunately, we have far less information to answer these questions than we should.