Radiation doses from computed tomography in Iraq

Abstract EN

Radiation doses to Patient during CT scanner and the radiological risk are significant.

Patient dose survey has been conducted toinvestigate the Iraq patient radiation dosesreceived in CT scanners in order to established reference dose levels.

These doses are Entrance Surface Dose (ESD),computed tomography dose index(CTDI)), and dose length product (DLP).

Two CT scanner were investigated in this study were, Siemens Somatom Plus 4, located in at medical city of Baghdad, and Philips, Optimus located in privet hospital at Baghdad.

ESD were measured by TLD and Dosimax ionization chamber for head, chest, and abdomen for both sex and different weights.

The TLD results were higher than that measured with Dosimax due to scattered radiation .The scattering factor which is the ratio between dose measured by TLD and that measured by ionization chamber range between (1.14 – 1.34) compare to international measurement which is range between (1.1 – 1.5).The (ESD) measured by the two methods were agree well after the subtraction of scattering dose, and have compered with original research.

Dose profile were measured using array of TLD chips shows that its full width at half maximum is(7.99mm) approximately equal the slice thickness(8mm).

Our results compare with reference level at U.K, European Guidelines and other studies.

Average ESD for abdomen in our study equal 9.96 mGy is higher than UK reference value 5.6 mGy because in Iraq hospital they used low filtration (1.5 mm Al) compared with UK standard filtration that is greater than 2.5 mm AlReduction of mAs result in reducing the time rate of photons thus the dose will be decrease and the image quality was good.

Head CTDIw results agree well with Greece results and DLPs higher than other studies because our protocol was using large irradiation volume.

For abdomen our results of CTDIw and DLP agree well with other results for chest examination CTDIw is lower than other results but DLP agree with U.K reference level.