Dos and don’ts of CT scanning in C-19
There’s no doubt that the safest way to detect C-19 infection in a person is the RT-PCR test. In cases of breathing difficulties or a negative lab test report despite clear multiple symptoms of infection, doctors have been recommending imaging diagnostic tools like an X-Ray or CT scan to determine the level of chest infection, if any, and the appropriate line of treatment.
Do patients need a chest CT scan or X-ray?
With the surge in the pandemic, the demand for imaging diagnostic tools has only increased. These, however, should only be seen as complementary diagnostic tools in the management of patients. Considering that these tools are loaded with radiation risks can never replace laboratory tests and can only be secondary or supportive screening tools.
However, there is a possibility that the infection may not be detected in the RT-PCR test if the virus has mutated, or the test has been done prematurely. The test report will also show a negative result due to a testing error or the viral load is very low.
While the sensitivity of the RT-PCR test is only around 70-80 per cent, there have been many cases reported where the test shows a negative report.
Often, when a person appears to be symptomatic, a combination of laboratory reports and a CT or X-ray scan is taken as a guide to starting the treatment, which is followed by another RT-PCR test repeated after 24 hours.
How does CT scan work for C-19 treatment?
The patient data over the last year or so has shown that every C-19 patient is different with unpredictable needs. The role of imaging diagnostic tools has also become more prominent in such a given situation.
A chest computed tomography (CT) scan has always been used as a routine imaging tool for diagnosing pneumonia. Moreover, considering the large number of people getting infected, CT scans play an important role in initiating timely treatment of patients.
The results displayed by a CT scan are seen to be more accurate. The computerized process compounds the power of X-rays and sends radiation through a patient’s body and captures a 3-D view that shows the position, shape, and size of the organs in your chest.
As per the C-19 treatment protocol-2021, the sensitivity of CT for C-19 infection is at 98% compared to RT-PCR sensitivity of 70-80%.
X-ray as a diagnostic tool for C-19 patients
An X-ray is a simpler and most accessible form of diagnostic tool. It involves an imaging procedure using radiation to capture an internal image of your chest. Any abnormal formations are reported quickly and can be investigated further if required.
X-ray is usually considered an emergency diagnosis tool as it is fast and easier to use than computed tomography.
Warning on the overuse of imaging diagnostic tools
Patients with mild C-19 symptoms should be careful in undergoing a radiation scanner. The amount of radiation used for a CT scan is much more than what is used for an X-ray.
According to the international atomic energy commission for radiation protection and medicine, the overuse of CT scans increases exposure to radiation that increases the risk of cancer, particularly for young people as they age.
It has been observed that white patches in the lungs that are revealed in the CT scan of mild infections or asymptomatic cases get cured with time.
An X-ray also costs less than a CT scan. While a chest CT/High-Resolution CT scan can cost anything around Rs 3000 to 8,000 depending on which part of the country you are in, an X-ray for the same purpose will likely cost on an average between Rs 200-2500, depending on the type of X-ray and radiology lab available.
The imaging diagnostic tools are only recommended as supportive tools for doctors, and patients should sparingly use them on a case-by-case basis. It is only the combination of lab tests, medical history, physical exam and clinical condition, and if need be, then an imaging tool like X-ray or CT should be used as a line of treatment.
by Dr. Shabnam Mir is the Consultant Physician and Head of Clinical Services, Delhi/NCR at Antara, a Max Group company specializing in senior care.
(DISCLAIMER: The views expressed are solely of the author and The Health Master does not necessarily subscribe to them. The Health Master shall not be responsible for any damage caused to any person / organisation directly or indirectly).
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