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Radiation risks from CT Scans and MRI

By Flavia Nassaka

Experts explain danger in growing trend of self-prescribed diagnosis

The joy that parents experience when they have a child is unexplainable. The same joy is what they go through when; the mothers especially, are expecting. Many cannot wait to know the sex of their child. Thanks to technology, parents can now know what child they are carrying just a few months into pregnancy. Through a scan, a baby’s gender can be seen at as early as eleven weeks.

Apart from being used for determining the kid’s sex, ultra sound, Computerized Tomography (CT), and Magnetic Resonance Imaging (MRI) scans are a new trend in treatment. They are used to check ailments of the major organs like the head, gallbladder, kidneys, liver, heart, pancreas, and spleen.


An MRI is an advanced diagnostic imaging process that produces three-dimensional pictures of a person’s body, by combining a strong magnetic field and radio waves. A CT scan uses X-rays and computer technology to create an image of internal structures of the body.

All these according to Dr. Mary Nalubega, a Diagnostic Imaging expert at Mulago hospital fall under the category of improved diagnosis and treatment that help an expert pinpoint a problem exactly.

“They give more information and faster,” she says.

Nalubega says as a result, there is a new trend of inquisitive patients requesting for scans even when the doctor has not recommended it.

At the Mulago National Referral Hospital, more than 20 patients are referred by doctors to undergo a CT scan, every day. In reality, hundreds do ultra sound and MRI scans daily. This is a sophisticated procedure that exposes all features of internal organs.

The increasing number of people going for scans is explained by a number of private clinics offering the service sprouting out around Mulago.  Moving around the hospital, one is often confronted by sales people asking if one needs a scan service.

Dr. Israel Luutu, a radiologist is an admirer of the modern diagnosis equipment. He says it cuts down the numbers of people requiring surgery. In the past, surgeons had no way of determining what the patient is suffering from without cutting them up.

Luutu says, however, the new diagnosis equipment has risks associated with over exposure to radiation, for example, among pregnant women.

While no large studies have been done on the effects on the fetus of performing a CT scan to a pregnant woman’s abdomen, the expert says a fetus over exposed to radiation can, in some cases, develop physical and mental growth problems.

Also, research work published in the Lancet, an online medical resource shows that children and young adults who had had multiple CTs have a small increased risk of leukemia and brain tumors in the decade after their first scan.

Luutu says apart from Ultrasound and MRI that have no or little doses of radiation, CT scans should particularly be used only when it’s absolutely necessary. He says one scan produces over 50 times the radiation produced by an X-ray.

He warns that some unscrupulous doctors may choose to use this as a default test for the routine abdominal pain with the aim of increasing one’s hospital bills yet radiation from X-rays damages the DNA which can cause cancer or ovarian damage in women.

The risk of cancer from a CT scan depends on age and the body part scanned, according to Luutu. Children and young women are at greatest risk. He says the breasts are especially vulnerable, so a CT scan to the chest carries the greatest risk for women.

But fellow radiologist Dr. Elsie Kiguli of the African Center for Global Health and Social Transformation (ACHEST) says the risk is the same for both children and adults explaining that CT scanners are calibrated in terms of output, but the amount of radiation a person absorbs depends on gender and weight.

“No scanners have been created just for children, but all can be adjusted to emit radiation appropriate for children. To avoid over-exposure equipment should be regularly tested because with no safeguards, a machine can produce more radiation than normal without anyone noticing,” she adds.

What an informed patient should know

Kiguli advises patients to always ask how much radiation the procedure can deliver and if there an option of using a non-radiation scan before considering a CT scan.

If the doctor cannot answer those questions, the medic says then they should not order the test because experts should know the benefits or risks of every test they recommend.

“At the end of the day a CT scan could be the best option for you. Being risky doesn’t mean something is bad but it should be used with caution,” says Kiguli.

For Pregnant women, Kiguli says, it is important to realize that almost all imaging tests expose the fetus to very low levels of radiation and should not be a cause for concern. However, it is good practice if possible to avoid those tests and procedures that directly expose the uterus or abdomen to radiation.

Luutu explains that patients using the machine for the first time may experience an allergic reaction to the iodine-based contrast dye, which can cause symptoms such as nausea, vomiting and occasionally a life-threatening response called anaphylactic shock which may come up as an emergency. Therefore, when undergoing a scan, emergency medication should be available.

He also advises that before a scan of any nature, hydration is required because patients who are dehydrated or those with impaired kidney function may experience acute renal failure from infusion of the contrast dye.

The doctors made it clear that this radiation danger does not apply to radiation therapy for those who have cancer.

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