CT scans: Should we undergo routine CT scans? Benefits, risks, and things to consider

CT Scans: CT scans or computerised tomography scans are a medical imaging technique which have become an important part of the modern medicine practices, as they help in diagnosis of diseases, and have been helpful in diseases like cancer. They are non-invasive procedures, through which images of the internal organs of the body can be acquired for examination. However, some people believe that CT scans can be a part of regular health screening procedures. Is that true? Financial Express Online explains.

CT Scans explained

CT scans is an imaging technique that makes use of ionizing radiation or X-rays.

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“CT scans are computerised tomography scans that are carried out by machines that use X-ray radiations to acquire images of the body of the patient. So when the images are acquired, we are able to get very very thin slices of the internal organs, by which we are able to analyse any abnormalities that might be happening inside and as a result, we can diagnose the disease,” explains Dr Ruchira Marwah, Chief Consultant Radiologist at Masina Hospital.

Dr Deepak Patkar, Director (Medical Services) and Head of Radiology, Nanavati Max Super Speciality Hospital further explains, “CT scan is a cross sectional imaging modality which uses a series of X-ray images taken from different angles around your body with the help of a rotating X-ray tube. A row of detectors are then used to create images (slices) of the bones, blood vessels and soft tissues inside your body. These X-Ray measurements, shot from different angles are then analysed using computer based reconstruction algorithms to produce tomographic (cross-sectional) images (cut or slice) of the area scanned.”

“CT scans are useful in detecting various diseases, variations, or injuries in any part of the human body, from head to foot. It can show air, fat, soft tissue, calcium, blood, bone, metal, etc in the images thereby allowing the radiologist to precisely read the abnormalities in the tissues,” Dr Pradeep S, Senior Radiologist, Fortis Hospital, Bannerghatta Road, Bangalore, said.

Benefits of CT scans: Where can they be useful?

CT scans are beneficial in several different aspects of medical treatment, including in emergency situations, trauma and in the cases of long-term and severe diseases.

“CT scan is used to assess infections, interstitial lung disease, airway disease, cancer detection and spread and assisting in CT. CT guided biopsy means CT scan gives 3D localization of a pathology and provides a safe road map limiting adverse complications,” Dr Rahul Vakharia, Consultant Radiologist, Wockhardt Hospital, Mumbai Central, said.

Dr Puneet Mallhan, Associate Consultant Radiologist, Wockhardt Hospital, Mira Road, said, “CT scans can be helpful in getting a clear image inside the body and aid in diagnosis of bleeds, infarcts, tumors, infections, cysts (fluid-filled sac-like structures), and bowel disease. Other issues like kidney and bladder stones, urinary tract blockage, or other urinary tract diseases, liver diseases and inflammation of the pancreas, problems of the pelvic organs, bony structures injuries including the shoulder, elbow, wrist, hand, hip, knee, foot and ankle, and even enlarged adrenal glands can also be diagnosed with CT scan. Heart study can also be done on CT.”

“One of the very good advantages of CT scans is that the scans can be acquired very fast. Scans of the entire body can be acquired within a few seconds. That is one big advantage. They are also advantageous in all kinds of diseases and abnormalities that can happen in clinical practice, like headaches, or breathlessness or abdominal pains. In such conditions, we can conduct a CT scan and see what is going on inside the body. It is especially beneficial in cases of trauma and stroke. In cases of any injury, CT Scan can be done quickly and easily. So, CT Scans are the preferred modality in emergency settings also. They are also very advantageous in cases of cancer, and at multiple levels. First, they help in the diagnosis of cancer, and then in the staging of cancer – how far the cancer has spread, is it localised to one place or if has spread to other places of the body. And then after treatment also, CT scans can be repreated to see how the cancer has responded to the treatment. So, CTs play a very very important role in cancer imaging,” Dr Ruchira added.

Should people get routine CT scans done as part of health checkups?

The general consensus of all the doctors was to not get a CT scan done as part of the routine check up.

“Ideally, there is no indication for going for routine CT scans. If the patient has some clinical condition, some problem, only then does it make sense to go ahead for a CT scan because whatever said and done, we are using X-Ray radiation in the process, and unless that exposure is meant for our benefit in some way, it is avoidable. So, unless and until it is clinically indicated, we should not go for unnecessary CT scans,” Dr Ruchira said.

Dr Pradeep and Dr Puneet seemed to agree with her view.

“There is no requirement of routine CT scans in the absence of any illness or indications. Even when indicated, repeated CT scans should be avoided. Alternatively MRI or Sonography should be tried when possible,” Dr Pradeep said.

Dr Puneet advised, “People should not get a CT scan done on their own, and should only do it when the doctor asks them to. There are many people who are rushing to get a CT scan done, which is a strict no no.”

Dr Deepak, while agreeing to avoiding unnecessary CT scans, also gave an additional point of view. “CT scan involves radiation and is advised only when necessary. It is not a primary screening modality like Ultrasound. However, during the pandemic, CT proved to be an excellent modality to diagnose COVID-19 patients, who were less likely to be detected through routine testing or screening. Specific guidelines were laid down before CT could be used in this context. A larger study is necessary to clearly ascertain the risk versus benefit ratio of using CT Scan for routine diagnosis,” the doctor said.

Routine CT scans: Why not?

Since CT scans are beneficial, why should routine scans be avoided?

“Since CT scans are using X-Ray radiation, it has its own disadvantages and excessive exposure can even lead to cancer in the long run. Although, the kind of machines we are using these days use very less radiation and despite that we can acquire very good images and diagnostic images can be attained. In radiology practice, there is this ALARA principle – as low as reasonably achievable. That means that whenever we are carrying out any imaging, whatever minimum radiation we can have in which we can get maximum information is ideal and this is the main principle we should follow. Unnecessary scans should be avoided,” Dr Ruchira said.

“Repeated CT scans can be harmful as these can cause damage to your cells/DNA. One CT scan equals to many chest x-rays and can make one fall prey to cancer in later life. Moreover, the radiation can be more dangerous for children. Abdominal CT scan side-effects include bloating, allergy (If contrast/dye is given), diarrhoea, nausea, vomiting, and constipation.” Dr Puneet said.

Still, all of the doctors were of the view that in cases where CT scans were recommended, the benefits from the imaging outweighed the ill-effects of the radiation.

“The general apprehensions about CT scan are centred around the use of ionising radiation and possible reactions/side effects of the intravenous contrast (dye) used for better visualisation of certain bodily structures. The effective doses from diagnostic CT procedures are typically estimated to be in the range of 2 to 20 mSv. At the same time, we are constantly exposed to natural background radiation. Approximate effective radiation dose for a CT Brain would be comparable to natural background radiation for about seven months. According to some theories, exposure to ionizing radiation may increase a person’s lifetime risk of developing cancer by a small amount. However the benefit of an accurate diagnosis or planning outweighs the associated risks. The risk of exposure to ionizing radiation is of significant concern in the paediatric population because of their young age and physiology. Which is why paediatric diagnostic protocols are designed and customised in a way to provide minimum radiation exposure possible,” Dr Deepak explained.

“Risks or side effects of CT scans can be from the X-Ray radiation, from the iodinated intravenous contrast or from dye. X Rays used in CT scans are hundred times more in quantity as compared to those used in chest x-rays. It’s ionizing radiation that can cause alterations in DNA and in some rare cases, cancer. But when used judiciously and within permissible limits, the benefits overweigh the minor risks. Similarly, iodinated contrast which is injected into the veins during CT scans can cause allergies of varying severity and causes anaphylactic shock or death in rarity. They can also harm the kidneys; hence checking renal function before contrast scans is a must in order to avoid contrast injections for people with kidney compromise. However, when used judiciously contrast is by and large very safe,” said Dr Pradeep.

Frequency of CT scans

Keeping in mind the ill-effects of the CT scans, all of the doctors have said that CT scans should be avoided if there is no illness. As far as other aspects are concerned, the frequency of CT scans depends on the illness and the treatment, and therefore, it varies from person to person and illness to illness.

“Having told about the technique, benefits, risks, indications etc, it is important to understand that CT scan is a great boon to the medical fraternity because of its ability to recreate images of the human body and its pathology in innumerable projections which helps clinicians to treat, plan surgeries, chemotherapies and view results of treatments, failures or complications as well,” Dr Pradeep said.