Imaging Studies - Our Children are Glowing

Imaging Studies - Our Children are Glowing

Imaging Studies - Our Children are Glowing

Children have ten times the risk for CT Scan caused cancer compared to adults. Ultrasounds and MRIs, whenever appropriate, should be substituted especially in the younger population

     
Imaging Studies - Our Children are Glowing
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Recently, mainstream media reported several incidences of radiation overdoses from Cat Scans. And, over a decade ago the Brenner study estimated that out of 1.6 million children who get CTs every year, 1500 will die of cancers caused by the CT itself. Could modern imaging technology be destroying us and our future generations?1,2

This health report is about one of the more recent innovations of the x-ray, the result of combining them with the processing power of the microcomputer: Computed Tomography (CT) , otherwise known as the Cat Scan. It has its hazards. Accidents can happen, and even its proper use comes with a price. And this in depth report will conclude with some surprising facts. Some disturbing facts. But first...

Some History

hand x-rayThis is the world's first and undoubtedly best known x-ray.  It's an exposure of the left hand of Anna Rontgen, spelled Roentgen also.  It was taken November 8,1895 in the research laboratory of her husband, Wilhelm, at the University of Wurzburg, Germany.  Her hand was placed between the x-ray beam and a plate with an emulsion of a barium compound.

Roentgen had noticed that something coming from his experimental Crook's tube was making his barium coated plates effervesce.   And whatever it was seemed to mysteriously penetrate solid matter.

Many scientists had been working with the new Crooks tube which bent electron beams and produced high energy radiation in the process.  Quantum physics and the study of atomic particles were all new concepts and experimental scientists were discovering all sorts of things.

Rontgen wasn't the first person to see the effects of his x-rays.  But as so often happens in science chance favored his prepared mind and he was the first to publish a paper describing the strange new ray that could penetrate solid matter.  He won the 1901 Nobel Prize in physics.  The Roentgen is a standard unit of x-ray dosage and has carried his name since.

Wilhelm Roentgen Wilhelm Roentgen 1845-1923 

The roentgenogram, now usually called an x-ray, became an integral part of practicing medicine.  Early patients included a small child with a penny stuck in her esophagus and a young man who had a needle stuck in his foot.  In 1901, Thomas Edison volunteered one of his x-ray machines to aid in the treatment of wounded President McKinley, but the President's head physician, a gynecologist, had closed the wound and pronounced that the president was improving.  The x-ray wasn't necessary.

Roentgen continued his experiments.  He died of intestinal cancer in 1923, four years after his wife, Anna, died of an unspecified and painful lingering illness; a term often used in those times instead of cancer.

Any history of x-ray must include the sometimes capricious and occasional careless underestimation for the harm that it can do. The early machines were calibrated by noting how long it took a beam to burn the skin of laboratory personnel.  Dentists would hold the small dental plates in place while the exposures were made.  After they noticed their fingers became burned they had the patients hold the plates instead.  Eventually, someone thought of putting a bite tab on the plates. These and many other workers who had focal exposures to their extremities developed a high incidence of sarcomas, a form of cancer.

Up into the 1950's, radiologists would do fluoroscopic exams by sitting in front of a screen and observing real-time images of barium passing through different organs.  They received a full dose of raw radiation and many tumors, and leukemia were the result.

Thyroid disease was treated with raw radiation.  So was acne.  And up into the mid-1950s shoe stores would have x-ray machines designed to show one's toes wiggling inside the shoes.  It was unmonitored, you could look at your toes move as long as you wanted, and it was more raw radiation delivered to the entire body, but mostly the head and feet.

Some Basics

This is an optional physics section and it contains all the things you ever wondered about radiation.  Where it comes from, and what all those units of measurement really mean.  Scientists live to measure.  There is no science without measurement.

A good place to start is the coulomb.  It is a unit of electrical charge and is the basis for measuring radiation.  One coulomb is the amount of electricity transported in one second using one amp of current.  Extra Credit:  Unit invented by the scientist Charles Coulomb. The roentgen, or R, was an early used measure of radiation.  It is proportional to the amount of radiation required to liberate all the electrical charges in one big coulomb, called the stat coulomb.  It's a measure of energy.

Another unit of radiation, first proposed in 1918, is the Rad, the radiation absorbed dose.  It focuses on the amount of energy actually absorbed by tissue.  So much energy, in joules, that can be absorbed by one kilogram of matter. Rem stands for roentgen equivalent in man.  It's just a rad modified by a weighting factor that varies with the type of tissue it's penetrating. Rems are easy, they're just modified Rads.

The Sievert, or Sv, is another measure of how much energy is actually absorbed.  One Sv is how much energy, a joule, is absorbed in one kilogram of any material, including human tissue. One Sv equals one Gy, or Gray.  Gray units seem to be used more to calculate equivalent units of energy that is absorbed.  The Seivert chamber is an instrument that measures radiation dose and the units were called seiverts.  For all practical purposes one Gy equals one Sv.  Gy and Sv are also used if there is more than one unit.

Over the years the preferred or more popular unit of measure has changed, the gray and seivert seem to be more commonly used now, probably because they measure more accurately the amount delivered to any particular tissue.  There are weighting factors for various organs. One gray equals about 100 rads which for most radiation exposures equals 100 rems.  People who deal with radiation and its effects can jump between units with ease.  For the rest of us, sometimes, the units can be confusing.  Just remember that when you go from rads to grays, take away two decimal points.

What's Radiation?

Anytime high frequency waves, energy, or atomic particles come out of a nucleus, radiation has taken place. Certain elements have unstable atoms and as they release particles and energy the nucleus changes.  As they change, they create isotopes or different forms of the same element.  Uranium 238 is a heavier isotope than uranium 235, for instance. Isotopes of any particular element must have the same number of protons, but can have different numbers of neutrons.  The atomic number of any isotope, say Uranium 238, is the same as the number of protons.  Isotopes have a different atomic mass number which is the total number of neutrons and protons.  They can be unstable, and that's what causes them to radiate.

Radiation can be alpha particles, a helium nucleus with no electrons, beta particles, the electrons or positrons that have been split off their nuclei, or gamma rays. Alpha particles are low energy entities and are stopped by paper or clothing. 

Beta particles have more energy and are the smaller electrons and positrons that can ionize DNA by knocking off some of its electrons, spawning mutation in the nuclei.  Beta particles can be emitted for years after a nuclear explosion or accident, depending on the type of bomb or reactor used--Chernobyl and Fukushima would be an example of the latter.  Beta emitters are used in radiation medicine to kill tumor cells.

Gamma rays are high energy radio waves that do their damage by killing tissue and ionizing DNA.  Gamma rays come from the nucleus; x-rays come from the electron field surrounding the nucleus or from an x-ray tube.  Their wavelengths and frequencies overlap.

Radiation Sickness and some other facts

To understand radiation better, we will talk about big accidents, like Chernobyl and Fukushima, and smaller scale accidents; accidents that take place every day in every x-ray department.  They are related and the study of one helps understand the dangers of the other.

Acute radiation sickness is the result of direct damage to the body's tissue caused by the three forms of radiation described above. At acute exposures of 1000 mSv radiation syndrome symptoms in the form of nausea, vomiting, anemia, and headache begin. At doses of 5000 mSv half of those exposed will die within six months. At 10,000 mSv, or 10 Svs, death is inevitable. The highest exposures at Fukushima were measured at 17mSv and resulted in skin burns to exposure areas.

According to a 2006 WHO report the Chernobyl accident had caused 47 immediate worker deaths. Eventually, 4,000 people developed thyroid cancer. Initial radiation levels were 300 Sv, not mSv, per hour at the plant. Just a few minutes of exposure was fatal. Two people died within hours, a total of 40 died of acute radiation sickness within a few weeks. And there were an estimated 30,000 cancer deaths within the next few years.

The Fukushima radiation levels rose, after the accident, to a high of 1100 mSv per hour inside the plant. Some reports claim 50 workers were chosen-volunteered for a certain-to-be fatal assignment to work in high radiation areas. Other reports claim the workers alternated shifts of 50 men each. Estimates of long term cancer deaths haven't been made as of yet. As for the customary acceptable radiation doses for workers of 50 mSv per year, the "acceptable" radiation dose changed to 250 mSv for the duration of the crisis. Current information remains sketchy and it can't be determined what the plan will be when all qualified workers reach their limit.

Although, nuclear accidents gives us a perspective on the magnitude of radiation exposure, the risks of CT imaging studies can sometimes be as dramatic!

Normal background radiation from all sources, natural, cosmic x-rays, and man made sources, is around three mSv per year. Nuclear plant workers are allowed to have 5 rem or 50 mSv per year.

In just three decades the per capita exposure to medically generated x-ray studies has gone from 0.5 mSv to 3 mSv, equal to the average background radiation. Most of the increase comes from CT studies. We're almost to the point where one in every five emergency department visits will have CT studies of one kind or another.3

Radiation exposures from x-ray studies: 4

Chest x-ray                                0.1 mSv

Mammography                            0.4 mSv

CT Head without contrast            2 mSv

Intravenous Pyelogram                3 mSv

CT Abdomen & Pelvis
without contrast                          15 mSv

The latest generation of scanners, all of them, have technology to reduce radiation exposure dramatically. It's the human interface with the new technology that is error-prone. In 2009, there was a rash of radiation overdoses due to either malfunctioning new scanners made by GE and Toshiba or human errors in their programming.  Apparently, the scanners were erroneously programmed to raise radiation doses on smaller patients instead of lowering them.

As well, there appears to have been operator error. My sources tell me the new multislice scanners are so fast that some operators did not think the scan had been done and could end up taking several scans on the same patient. Patients actually reported skin burns, hair falling out, and confusion.  Cancers, especially leukemia, is probably inevitable in many of these patients.

So, let's look at the long term dangers of CT scanners: Cancer.

The Brenner Study is the landmark scientific publication that looked at the largely unaddressed problem of CT utilization-overutilization, and the cancer risk for pediatric cases.  There are many published papers of Dr. Brenner, but when people talk about the Brenner studies, there are two; one in 2001 estimated the risk of fatal cancer, not just cancer.  The second, published in 2007, measured progress in implementing some of the obvious implications of the first.5,6

In the 2001 study there were about 600,000 pediatric abdominal and head CTs. Using acceptable scientific principles that have held up against peer review, Brenner estimated 600 of these patients will die from a cancer caused by the scan itself.  Just for one year. The second study updated his estimates using current data and concluded, amazingly, that about two percent of all cancers were caused by CT studies.  Not just the fatal ones, this figure was all cancers!

Let's go over that estimate again: The study suggests that two of every hundred cancer cases were directly attributable to CT radiation.  Children have ten times the risk as adults for 'CT caused cancer'.  They're going to live more years after the exposure but they are more prone to damage because the radiation sensitive DNA strands are doubling more frequently. Put another way, Brenner, estimated that of the 1.6 million children who get CTs every year, 1500 will die of cancers caused by the CT itself.

2007 was also the year a survey showed that less than half of our country's radiologists were aware of even the slightest connection between CTs and cancer. Worse yet, less than 10 percent of emergency physicians knew of the connection.

Just check the box

It's so easy to check a box or have a protocol to have scans done before the doctor even sees the patient, a common practice at many institutions now. In Sweden patients arriving by ambulance at the accident hospitals receive a full body scan as they are being moved from the ambulance to the trauma room, before any doctors or nurses have seen them; clothes on, immobilized on a backboard.  It takes less than 90 seconds and delivers at least 100 mSv.  Then after the patient is undressed and examined, a second follow up scan is sometimes done, another 100 mSv.

One of the popular studies for emergency doctors for a while was a "CT of the chest with and without contrast with extremity run off." It was an attempt to diagnosis every single patient with a pulmonary embolus.  So here are the scans this patient would get:

  • A scout CT for positioning.
  • A plain CT of the chest.
  • A chest CT with intravenous contrast.
  • A CT of both lower extremities arterial phase.
  • A CT of both lower extremities venous phase.

Each was a full blast and the patient ended up with more than 100 mSv. The good news is that this protocol is no longer used. Another was the abdomen/pelvis protocol that included:

  • A scout
  • A non-contrast scan abdomen/pelvis.
  • Abdomen/pelvis arterial phase.
  • Abdomen/pelvis venous phase.
  • 5 minute delay abdomen/pelvis.

The good news is that these protocols are no longer used, we hope! But remember this, a patient can receive more than just one scan, there's the scout scan for proper positioning.  Scout films are often done more than once, sometimes several times, especially with unsedated pediatric patients.

What needs to be done?

Decrease CT utilization - Studies suggest one-third of all CTs are unnecessary.  I'm not sure it's that easy to decide what's necessary or not but the number of scans could undoubtedly be reduced. And, about 10 percent of scans are repeated for avoidable reasons, like positioning errors.

Substitute CTs with Ultrasounds and MRIs, whenever appropriate - There is no radiation with ultrasound and study after study has shown it is just as good in diagnosing gall stones, kidney stones, blood clots in the legs and at times appendicitis. However, it does requires more operator experience to be accurate and most hospitals still do not have 24 hour ultrasound availability. And on the plus side there is also a trend to substituting MRIs for CTs at some institutions.

Modify the exposure protocols - A protocol for scanning determines what the parameters of the exposures will be and how they will be changed for pediatric patients.  Exposure can be dramatically reduced by about 60 to 70%. This gets actual exposure equivalent to that of a week or so at the beach.

Currently in most institutions, the machine's vendor (G.E. or Toshiba for instance), the chief radiology technician, and the hospitals radiation officer, usually one of the radiologists, will sit down and decide the parameters which can and do vary from institution to institution.  The protocols are then programmed into the scanner.  It's this last step, the programming that has led to many of the terrible exposure accidents recently.7

Certify the CT Techs - This next item came as a surprise to me. I did a quick and dirty survey of about two dozen radiology technicians who were doing CTs. Many were totally unaware of protocols for pediatric patients, or the techniques that could be used to reduce radiation by as much as 70%. As an example, only three states in the U.S. require the scanning tech to be certified in CT scanning.  Currently, in the other 47 states, any radiology technician with his basic certified radiology technician license can do CTs.  Data is not available for the UK or Canada. A customary practice is that the tech sits in the CT control room and watches the more experienced techs do scans for about two weeks.

What are known as CARE laws, Consistency, Accuracy, Responsibility, and Excellence in Cat Scanning, have been advocated for years and amazingly not passed on the grounds that such a law is not necessary.  CARE requires techs to orient to their hospital's or imaging center's scanner and do a proposed 100 supervised scans. Perhaps, the only way to get the benefits of CARE laws is for the government payers, Medicare and Medicaid, to refuse payment unless the scan is done by a CARE certified tech.  Although we have more than enough regulation, this one is long overdue.

And, implement a national mandatory Radiation Dose Registry - This long term monitoring project would collect and store data on radiation doses for each individual patient. Currently, there is a voluntary program with only a few participating institutions. This would give us scientific measures of the effects of CT associated cancers. Currently, assumptions must be made from the Japanese bomb survivors and to a certain extent, the plant workers at Chernobyl.

A Final Word

This article doesn't touch upon the important issues of radiation exposure of women, such as mammograms, and the special concerns for ovarian, uterine, and especially breast tissue.  Nor does it deal with the question of airline workers and their chronic exposure to cosmic radiation.  These are entire in depth reports in themselves.

Certainly the Brenner papers are what would be considered landmark studies in that they clearly showed a danger of CT technology.  Since then study after study has supported the original findings and finally, ten years since the first study, momentum seems to be growing for standardization of protocols.

The American College of Radiologists has developed protocols and standards for reduced radiation scanning. They need to be implemented.  I interviewed the American College of Radiology's chairman of its Medical Physics Commission, Richard Morin, PhD, on a number of topics. He was unaware of any updated survey to see if more than half our country's radiologists were aware of the potential dangers of CT. He indicated that his personal interaction with the radiologists he meets and deals with every day indicates a growing awareness of a need for change.

Certification should also be required for any person doing the scans and for each individual machine that person may be using.

So, what can you do in the meantime when your doctor orders a scan?

  • Read this article again, especially the physics part so you'll know the lingo.
  • Ask the doctor if an ultrasound or MRI would be just as good.
  • Request a reduced radiation study.  Ask what the dose will be and compare it to any of the many CT dose tables available.
  • If your child is getting a scan, request adequate sedation.  Many children get more than one because they're not properly sedated.  There is no excuse anymore. It's easy to sedate children now, there are multiple drugs that can be used.
  • Ask the tech, or his chief tech, if they comply with CARE law standards. If the techs get a blank look on their face and don't know what to say or if anyone seems to be thinking you are a bother, ask for the radiation officer for that institution, and ask him.
  • Or change providers, institutions and make some phone calls, if it's not an emergency.

The Bottom Line

Be HealthSmart. Minimize you and your family's radiation exposure. You get enough background radiation as it is. Meanwhile are children are still glowing! 

Published August 24, 2011, updated June 20, 2012

 

Photo By:  Getty Images


References

  1. Sternberg S, CT Scans Boost Cancer Risk in Young Patients, Study Finds, Health, U.S. News & World Report, June 6, 2012
  2. CT scan cancer risk, Healthknot.com
  3. Reddy S, CT Scan Use Triples in 15 Years; Radiation Risk Justified? Health, abcNEWS, June 12, 2012
  4. Brenner D et al, Estimated Risks of Radiation-Induced Fatal Cancer from Pediatric CT, American Journal of Roentgenology, 2001, February; 176(2): 289-296
  5. Brenner D et al, Computed Tomography-An Increasing Source of Radiation Exposure, New England Journal of Medicine, 2007, November; 357:2277-2284

 

Senior Correspondent Jones was an emergency doctor in Southern California for 25 years before he moved to Texas where he is semi-retired and freelance writes for HealthWorldNet.com.  He also wrote a nonfiction novel, A Murder in West Covina, which is soon to be released in paperback

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