Could CT Scans Give Some Patients Excessive Radiation?

CT (computed tomography) scans are also known as CAT (computed axial tomography) scans. It is a non-invasive medical diagnosis scan that produces detailed three-dimensional cross-sectional views of internal organs using a series of specialized X-rays. It produces images in greater detail than standard X-rays.

The term "non-invasive" may be a misnomer. Although it is true that we do not cut or insert scopes into the patient, the patient does receive a dose of radiation from CT scans that may accumulate and have indirect consequences.

There have been various news reports coming out that ill-designed or ill-configured CT scanning machines and/or operator errors resulted in some patients receiving excessive radiation dosage. This was particularly true for a procedure known as the "CT brain perfusion scan", which is used to diagnosis stroke.

The symptoms of radiation over-exposure may possibly includes a band of hair loss in the same pattern as the brain scan, redness of skin, and nausea.

The New York Times reported of radiation overdose published in July 2010 ...

• 65 or more stroke patients had received overdose of radiation at Huntsville Hospital, which had up to 13 times the amount of radiation generally used. When questioned, the operators said they increased the radiation in order to get clearer images.
  
• 37 overdose at Providence Saint Joseph Medical Center
• 269 radiation overdose (over an 18 month period) at the Cedars-Sinai Medical Center with some patients receiving up to 8 times the normal dosage. At Cedars-Sinai and another hospital, a feature that technicians thought would lower radiation levels actually raised them.
• Over 400 people at various hospitals had received higher-than-expected radiation doses
• Many of the over-dose happened on scanners made by GE Healthcare.
• Manufactures of Toshiba scanners suggested machine settings that ultimately produced too much radiation.
  

Some patient testimony videos on the New York Times website shows patients with hair loss. One said that he had received the same amount of radiation as someone in Hiroshima during the atomic bomb.

You can listen to NPR (National Public Radio) reports on FDA's investigation of these hospital radiation overdose linked here.

The problem has become so widespread that there are websites and law firms that are accepting clients that may have been exposed to excessive radiation. For example, Lawyer Mike Hugo at Parker Waichman Alonso LLP talks about the radiation overdose problem in this video.

The above cases reported in the media are not typical cases. The are particular incidents involving ill-designed machines or human error.

LA Times article says ...

"The recent episodes of unusually high radiation doses delivered to patients at Cedars-Sinai Medical Center in Los Angeles and Glendale Adventist Medical Center were particularly egregious examples that involved inadvertently inappropriate settings on the instruments ..."^[7]

But even for the majority of the cases that does not involve ill-designed machines or human error, many people are questioning the overuse of CT scans.

The concern is that a typical CT chest X-ray emits 150 to 200 times more radiation than a regular chest X-ray. A CT brain perfusion scan is like 200 X-rays of the skull.^[12]

The New England Journal of Medicine says that ...

"Depending on the machine settings, the organ being studied typically receives a radiation dose in the range of 15 millisieverts (mSv) (in an adult) to 30 mSv (in a neonate) for a single CT scan, with an average of two to three CT scans per study. At these doses, as reviewed elsewhere, the most likely (though small) risk is for radiation-induced carcinogenesis."^[10]

Here is what Reader's Digest Your Health, What Works, What Doesn't have to say...

"a computed axial tomography (CT or CAT) scan of the chest exposes you to 10 millisieverts (mSv), or about as much radiation as you're likely to be exposed to naturally in three years.  A mammogram, on the other hand, may expose you to only about 0.7 to 1.0 mSv, or the amount of radiation you'd be exposed to naturally in three months.  Dental x-rays expose you to even less -- about the amount of radiation you'd get from nine hours of flying at 30,0000 feet in a jet."[page 388]

It does some radiation level comparisons on page 235...

• Dental X-ray: 0.004 mSv
• Chest x-ray: 0.1 mSv
• Mammogram: 0.7 mSv
• Coronary angiogram: 4.6 to 15.8 mSv
• CT scan, head and chest: 11 mSv

How much is a millisieverts? A person (excluding flying) receives about 3 millisieverts of natural background radiation a year. A typical radiation from a single coast-to-coast airplane flight is 0.02 millisieverts. 50 millisieverts is "thought to be the lowest dose at which cancer may occur in adults. It is also the highest dose allowed by regulation in any one year of occupational exposure." -- according to HowStuffWorks.com

Half of all medical radiation exposure are from CT scans.^[4]

A WashingtonPost.com article gives some estimates ...

• For every 1000 to 2000 CT scan, one fatal cancer case is produced.
• Risk is higher for children with estimate of one cancer case for each 500 scans.
  
• For a 20-year-old female, it could be as high as one cancer case per 143 scans.

LA Times^[7] also gives more statistics ...

• "The highest doses of radiation are routinely used for coronary angiography, in which cardiologists image the heart and its major blood vessels to look for blockages or other abnormalities. Under the normal dosages of radiation for the procedure, about 1 in 270 women and 1 in 600 men who receive it at age 40 will develop cancer as a result"
• "For a routine head scan, one in 8,100 women who undergo the scans and one in 11,080 men will develop a tumor."^[7]

NPR reports that for a 40-year old woman who toke an adbominal or pelvis CT scan, her risk of cancer from the radiation of that scan is 1 out of 250.^[13]

The amount of radiation exposure also depends on the facility, machine, and operator. One study found that there was a 13-fold difference in radiation exposure for the same scan in different institutions.^[3]

Because children should not be exposed to the same radiation dosage as adults, children that needs CT scans may want to look to centers that have experience doing scans on children. That way they will be more knowledgeable in re-adjusting the machines for children dosages. Make sure the facility is accredited.

Patients should also ask doctors what is the dosage and risk involved in an ordered CT scan. This will at least get doctors to think about the pros and cons before ordering a scan. Some may reconsider and decide to use other diagnosis tools such as MRI or ultrasound instead. And indeed there may be other cases where CT scan does turn out to be the best choice.

In 1980, about 3 million CT scans were done in the United States. In 2006, about 62 million CT scans. And now in 2010, it is about 68 million CT scans.

"MD Whistleblower" (a real doctor) says on his blog that about 10% of the US population undergoes a CT scan each year.^[8]

Some experts say that as many of one-third of CT scans may not be needed. For example, a "virtual physical" where a full-body CT scan is done on a healthy person would be deemed unnecessary.^[4]

A study led by Dr. Kristie Guite of University of Wisconsin-Madison examined the abdomen and pelvis CT scans of 500 patients.  They found that 52% of the patients had unnecessary CT scans.  The average patient had 11.3 millisieverts of radiation.  20% of the patients had 50 millisieverts, which is high enough to raise concerns.  And 7 in the study had 100 millisieverts of radiation which is known to raise the risk of cancer.^[14]

MSNBC article (with video) calls CT scans super X-rays and says ...

"The average American’s total radiation exposure has nearly doubled since 1980, largely because of CT scans."^[5]

There are many reason for the increase in CT scans...

• Greater availability and access to the machines
• Patients demanding the latest state-of-the art technology even when doctors did not prescribed the scan.
• Doctors practicing defensive medicine who worry that they might get sued if they failed to perform a diagnosis test when patient condition turns worst.
  
• Over-use of virtual physicals that uses full-body CT scan and virtual colonoscopy on non-symptomatic patients. (President Obama had a virtual colonoscopy in 2010^[ref])

All these news reports is not meant to discourage people from undergoing CT scans. Although, there are reports of overuse of CT scans, it is also true that there are many cases where CT scans are a medical necessity and is beneficial. It all depends on the particular case and circumstance. Of course, you should consult with your doctor as to the pro's and con's of CT for your particular situation.

The WashingtonPost.com article says ...

"Although some prominent medical groups have issued warnings against overusing the exams -- especially for children -- some experts worry about frightening patients away from the invaluable tests."^[4]

The article quoted radiologist Arl Van Moore Jr saying:

"You don't want people to avoid getting a potentially lifesaving diagnosis or therapy because they are afraid to get a CT scan ... When a scan is done the right way for the right reasons, the benefits clearly outweigh the risks of doing it."^[4]

Eric Hall, director of the Center for Radiological Research at Columbia University said in an USNews article ...

"Clearly in a patient that's symptomatic, a CT is a wonderful diagnostic tool ... What we are pushing for is to limit the use of CT to situations where it really is needed."^[6]

The article mentions three way to reduce radiation exposure from CT scans ...

• radiation dosage should be tailored specifically to the particular individual undergoing the scan.
• Avoid CT scans where there are other options such as MRI and ultrasound that would be sufficient.
• Reduce the number of CT scans prescribed.
  

CT scans have replaced a lot of exploratory surgery. Ten and fifteen years ago, a lot of exploratory surgery was done which came with it a lot of its own risks. But with CT scans doing the same diagnosis work but in an non-invasive fashion, it has reduced the number of exploratory surgery and its associated risks. So there are definite benefits to CT scans.

Article in physorg.com says that CT scans are safe. It quotes Dianna Cody, a professor of imaging physics at the University of Texas M.D. Anderson Cancer Center as saying ...

"Bad news sells ... But we're motivated to fight harder to make sure people know CT scans are safe. And to make it safer in the few places that have made honest mistakes."^[3]

Although the media may report about the estimates of 14,000 deaths from cancer in the United States due to CT scans (because that makes good headlines). This percentage is small when compared to the 68 million of CT scans done each year -- the majority of them are without incident and patients suffered no ill effects. When you take 14 thousand divided by 68 million, that is only 0.02%.

When you consider that there is one million cancer deaths each year in the United States, 14 thousand divided by one million is 1.4%. This is consistent with other estimates that indicates indicates that CT scans are responsible for 1.5% to 2% of all cancer cases in the United States.