Radiation dose to the eye lens from the CT portion of a PET/CT examination and possibilities of its reduction


Authors: Jaroslav Ptáček () 1,2,3;  Pavel Koranda () 2;  Iva Metelková () 2,3
Authors‘ workplace: Oddělení lékařské fyziky a radiační ochrany, Fakultní nemocnice Olomouc 1;  Klinika nukleární medicíny LF UP a Fakultní nemocnice Olomouc 2;  Ústav zobrazovacích metod FZV UP Olomouc 3
Published in: NuklMed 2012;1:63-67
Category: Original Article

Overview

Introduction:
PET/CT examination is vital for oncological patients nowadays. ICRP in its document Statement on Tissue Reactions ref 4825-3093-1464 proposes a new threshold of radiation absorbed dose in an eye lens for radiation induced cataract in the level of 500 mGy. It could be possible to achieve this value in a current clinical practice (especially during repeated CT examinations of a head). The goal of our study is to provide information about radiation dose to the eye lens from the CT portion of a PET/CT examination including possibilities of its reduction.

Material and methods:
We analyzed radiation absorbed dose to the eye lens in patients evaluated with a PET/CT in the Department of Nuclear Medicine of the University Hospital in Olomouc. Absorbed dose in the eye lens was determined for a PET/CT of a torso, brain, whole-body and for the CT used for attenuation correction. We evaluated 8 patients for calculation the dose from a torso and a whole-body examination including a head, respectively. Only one study was used for the dose calculation during a brain examination and an attenuation correction, respectively.

Results:
Eye lens radiation absorbed dose calculated by ImPACT program was 6 mGy, 3.7 mGy, 49 mGy and 1.4 mGy during examination of a torso, whole-body, brain and during attenuation correction examination, respectively.

Conclusion:
Our calculated values are in accordance with a literature. The highest eye lens radiation absorbed dose is from the brain examination. However, like in ther cases, it is still far under the threshold for a radiation induced cataract.

Key Words:
PET/CT, radiation absorbed dose, eye lens


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Labels
Nuclear medicine Radiodiagnostics Radiotherapy
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