Yes, it's generally okay to have a CT scan twice (or even multiple times) if it's medically necessary, as the benefits for diagnosis and treatment often outweigh the small, cumulative radiation risk, but you should always discuss the need with your doctor to ensure it's justified and consider non-radiation alternatives like MRI or ultrasound if appropriate, especially for children. There's no fixed limit, but each scan adds to a small lifetime cancer risk, so doctors weigh the benefits against this risk, particularly for frequent scans or in pediatric patients.
There is no recommended limit on how many computed tomography (CT) scans you can have. CT scans provide critical information. When a severely ill patient has undergone several CT exams, the exams were important for diagnosis and treatment.
If the scans are justified for diagnosis or treatment evaluation, there is no set number. For example, even two or more scans in a week or four in a month could be appropriate depending on your particular disease management. Again, for justified imaging scans the risks are low compared with the clinical benefits.
The low doses of radiation used in CT scans have not been shown to cause long-term harm. But for repeated scans, there may be a small increase in the lifetime risk of cancer. This can affect children more than adults. CT scans have many benefits that outweigh any small risk.
Does any radiation stay in the body after an imaging exam? After a radiographic, fluoroscopic, CT, ultrasound, or MRI exam, no radiation remains in your body. For nuclear medicine imaging, a small amount of radiation can stay in the body for a short time.
Reasons Your Doctor Might Order a Repeat Scan
For patients with chronic or serious conditions, follow-up imaging helps track how the disease is progressing. For example, repeat PET/CT scans in cancer care can show whether a tumor is shrinking, stable, or growing after treatment.
The effective doses from diagnostic CT procedures are typically estimated to be in the range of 1 to 10 mSv. This range is not much less than the lowest doses of 5 to 20 mSv estimated to have been received by some of the Japanese survivors of the atomic bombs.
Based on this pharmacokinetics, the ESUR guidelines recommend an interval of at least 4 hours between administrations of iodine-based and gadolinium-based contrast agents to reduce potential nephrotoxicity in patients with normal or moderately reduced renal function (GFR > 30 mL/min/1.73 m2) [3].
Unnecessary CT scans exposing patients to excessive radiation: Cancer cases could spike as result.
If your radiographers know you are nervous, they will take extra care in making sure you are comfortable and that you understand what is going on. Keeping your eyes closed during the scan sometimes helps. Preparation for the scan: Some CT scans need special preparation beforehand.
Try not to worry about radiation staying in your body after your CT scan. Any radiation will leave your body naturally within a few hours. You may want to drink extra fluids to help your body flush out the contrast medium, but other than that, there's nothing you need to do.
Reasons You May Need a CT Scan
In order to comply with radiation regulations, any person aged between 12 and 55 years of age who is having periods must have this examination within the first 10 days of their period (counting the first day as day 1), unless you have been sterilised, have had contraceptive implants/injections for three months or more ...
While they are generally considered safe, multiple CT scans over time pose a small increase in cancer risk. To keep you safe, radiologists take steps to reduce your exposure as much as possible.
A CT (computed tomography) scan uses X-rays to make detailed pictures of your body and structures inside your body. A CT scan of the abdomen (belly) can give your doctor information about your liver, pancreas, kidneys, and other structures in your belly.
In many conditions, such as cancer follow-up, severe trauma, or complex chronic disease, having 2 CT scans in a year is common and medically justified. In such cases, doctors weigh the benefit of better diagnosis or monitoring against the small increased risk from radiation.
CT uses x-rays, which require a small dose of ionizing radiation. MRI, however, does not use radiation. Radiation can cause cell damage that leads to cancer. However, because the radiation dose of a CT scan is so low, the risk of developing cancer due to the scan is small.
Sleep. Sleep plays a crucial role in detoxifying radiation after a CT scan. As you sleep, your body repairs and regenerates cells, addressing radiation-induced damage. Your immune system is also strengthened during sleep, enabling it to counteract radiation effects.
If someone is in a lot of pain, or if they find it hard to hold still for long periods of time, then a CT scan is often your best option. We can see things more clearly sometimes with an MRI, but those take anywhere from 30 minutes to an hour to obtain, depending on how much of your body is being scanned.
Examples include:
That can help them identify tumors, bleeding, blood clots, infection, fractures, and many other problems. You may need a CT scan if you are having unexplained dizziness or headaches. You may also need one if you recently suffered from a stroke or blow to the head.
To get accurate CT scan results, it is important to follow specific dietary instructions before the test. Eating the wrong foods before a CT scan can affect image clarity, especially in CT abdomen, CT pelvis, or contrast CT scans.
CT scans are very good at showing many tumors and enlarged lymph nodes, but they can still miss small or early cancers, especially in soft tissues or areas that are difficult to image. That is why doctors often combine CT with other imaging tests, lab work and, when needed, a biopsy to confirm a diagnosis.