CAT scans and radiation exposure – pro

Any unecessary exposure that is not supported by credible literature is inappropiate and should be avoided. Several articles comment on radiation exposure from CT scans. Trigaux and Lacrosse recognize that computed tomography is a diagnostic procedure that involves relatively high radiation doses. Crawley et al confirm that as a diagnostic imaging modality, CT gives higher patient radiation dose in comparison with other imaging modalities. In the UK, patient doses from radiological procedures were considerably reduced, but the efforts were largely offset by a corresponding rise in the collective dose from CT. A recent report from the Royal College of Radiologists in the United Kingdom acknowledges computed tomography as the single largest contributor to the collective dose from medical x-rays.

According to Seeram, patients are exposed to higher radiation levels from the use of computed tomography compared to most imaging techniques. There is a lack of awareness of the actual risks involved. The exposure to ionizing radiation in CT is emphasized in the CT versus MRI debate. MRI is safe. But MRI is more expensive and has limited availability. With health care costs already spiraling out of control, it is unlikely to supercede CT and the possible replacement has not occurred.

Therefore radiation exposure from computed tomography is still a matter of concern. The well known BMJ editorial by Rehani and Berry “Radiation doses in computed tomography. The increasing doses of radiation need to be controlled” published in the year 2000 is a discussion on the controversy. In the editorial, the authors point out the potential for increased radiation exposure from the advances in CT technology. Control of radiation burden is regarded as one of the parameters of quality control in computed tomography .
The advances in computed tomography ensure that it remains a versatile, affordable and readily available diagnostic modality more than three decades after its introduction. CT scans enjoy a pride of place in diagnostic radiology that was challenged but not usurped by MRI. The radiation risk is a disadvantage inasmuch the procedure involves exposure to relatively high levels. The issue of radiation exposure is once more the focus of current debate.

It should be admitted at the outset that there is no conclusive evidence of radiation risk. Although radiation doses are considerable, the doses are still well below acceptable limits of exposure. Expert opinion is divided on whether the increase in radiation exposure from CT scans is a matter of concern or not. Moreover, there is no doubt that the benefits outweigh the risks when there is a strong indication for a CT scan. The key issue is that there must be a valid indication for a CT scan to be performed. While this may appear to be a relatively simple matter, it is actually difficult to ensure the judicious use of CT scans in practice. With the increased dependence of modern medicine on technology, coupled with the significant contribution that CT technology continues to make to medicine, it is difficult for health care providers to forego a quick, non-invasive diagnostic tool.

An increased number of physicians and scientists agree that concerted efforts are required in order to reduce radiation doses from computed tomography. The shielding of superficial radiosensitive tissues and the optimum selection of settings are some of the technical possibilities. Manufacturers of CT scanners are capable of significant contributions in the development of low dose technology. The evaluation of acceptability of low dose techniques from a clinical perspective remains a potential challenge. Therefore, most modifications have inherent disadvantages and barriers to implementation.

Finally, CT scans are now used as a screening procedure. The full body CT scan though restricted to those can afford it has a wide appeal. The commercial potential of full body CT screening makes it an attractive commodity, but the long term benefits and risks are not clear at this time. The cost-effectiveness and large scale benefit of full body scans are still to be established.

1.Rehani MM, Berry M. Radiation doses in computed tomography. The increasing doses of radiation need to be controlled. BMJ. 2000 Mar 4;320(7235):593-4.

2. Crawley MT, Booth A, Wainwright A. A practical approach to the first iteration in the optimization of radiation dose and image quality in CT: estimates of the collective dose savings achieved. Br J Radiol 2001 Jul;74(883):607-14

3. Trigaux JP, Lacrosse M. Radiation exposure and computed tomography. Rev Mal Respir. 1999 Apr;16(2):127-36.

4. Royal College of Radiologists. Making the best use of department of clinical radiology: guidelines for doctors. 4th ed. London: Royal College of Radiologists, 1998.

5. Seeram E. Radiation dose in computed tomography. Radiol Technol 1999 Jul-Aug;70(6):534-52; quiz 553-6

6. Rockstroh G, Lieberenz S, Straubel U. [Quality control in computed tomography] Radiol Diagn (Berl) 1989;30(3):339-45

7. Nishizawa K, Maruyama T, Takayama M, et al. [Estimation of effective dose from CT examination] Nippon Igaku Hoshasen Gakkai Zasshi 1995 Sep;55(11):763-8

8. Wall BF, Hart D. Revised radiation doses for typical X-ray examinations. Report on a recent review of doses to patients from.medical X-ray examinations in the UK by NRPB. National Radiological Protection Board. Br J Radiol 1997 May;70(833):437-

9. Dhingsa R, Finlay DB, Robinson GD, et al. Assessment of agreement between general practitioners and radiologists as to whether a radiation exposure is justified. Br J Radiol. 2002 Feb;75(890):136-9.

10. Hopper KD, King SH, Lobell ME et al. The breast: in- plane x-ray protection during diagnostic thoracic CT-Shielding with bismuth radioprotective garments. Radiology 1997;205:853-858[Medline].

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