02 July 2008

Computed tomography: it is better to think well!

Computed tomography helps doctors detect almost everything, from tumors to kidney stones. However, some experts have expressed concern about the safety of this procedure, especially the increased risk of cancer. The fact is that the radiation dose received by the patient during scanning on a CT scanner is 500 times higher than the dose received with conventional radiography.

As part of the work to study the effect of computed tomography on health, scientists from hospitals in Florida and Washington, working under the guidance of Dr. Timothy Bullard, processed data on 1,243 randomly selected patients and estimated the dose received by each of the patients over the past five years. Despite the fact that computed tomography is the main source of radiation, the authors also paid attention to radiographs and mammograms. The results obtained are disappointing: on average, over 5 years, the patient received a radiation dose of 45 millisieverts. At the same time, 12% of patients received a dose of 100 or more mSv. With a conventional chest X-ray, the radiation dose is 0.02 mSv.

(Natural background ionizing radiation is usually about 2.4 mSv per year. In accordance with the Federal Law of the Russian Federation of 09.01.96 "On radiation safety of the population", the permissible dose of radiation for the purpose of diagnosis is 15 mSv / year.)

In a review written by a group of authors led by David Brenner from Columbia University (New York) and published in November 2007, it is mentioned that about a third of CT scans conducted in the United States are not necessary. The problem is partly due to the fact that patients are prescribed multiple tomograms, which can be avoided by improving the dialogue between doctors and patients. Moreover, doctors often practice "reinsurance medicine", which is based on the principle: "it's your fault if you missed something." And the appeal of computed tomography is that, in the absence of immediate side effects, it is fast, painless and leaves the patient feeling confident.

Considering that computed tomography began to gain popularity in the USA in the 80s, and it takes an average of 20 years for radiation-induced cancer to develop, work on studying this relationship has not yet been completed. However, based on the results obtained from the observation of 25,000 Japanese survivors of the atomic bombing and who received a dose approximately corresponding to that obtained with two computed tomography procedures, specialists of the US Food and Drug Administration estimate the risk of developing cancer induced by computed tomography as 1:2000. Moreover, this indicator is much higher for children.

Compared to adults, children have a higher life expectancy, in addition, their cells divide much faster, which increases the sensitivity of DNA to radiation. For a child, the estimated risk of developing computed tomography-associated cancer is approximately 1:500. Modern devices allow you to reduce the dose by 50% when scanning a child or an adult of small stature. However, despite the fact that the manipulations required for this are quite simple and take several seconds, according to the results of a 2001 study, many staff representatives ignore this opportunity due to lack of information, haste or laziness.

Based on the information available today, before conducting computed tomography, especially for children, experts recommend making sure that the procedure is necessary and that it cannot be replaced by ultrasound or magnetic resonance imaging (the nuclear magnetic resonance method is based on measuring the electromagnetic response of hydrogen atoms to their excitation by a certain combination of electromagnetic waves in a constant magnetic field of high intensity).

There are circumstances when computed tomography is indispensable, for example, the detection of severe head injuries or damage to internal organs or the diagnosis of existing cancer. In such cases, it is necessary to request a copy of the scan results from the doctor, which will avoid repeated scanning, for example, when changing the place of residence or the doctor.

Portal "Eternal youth" www.vechnayamolodost.ru based on the materials of Time


Found a typo? Select it and press ctrl + enter Print version