Radiation dose to the eye lens: does positioning really matter that much?

Bidragets oversatte titel: Dosis til øjenlinsen; Hvor meget betyder lejring af patienten?

Christina Baun, Kirsten Falch Braas, Kamilla D. Nielsen, Sanusa Shanmuganathan, Oke Gerke, Poul Flemming Høilund-Carlsen

Publikation: Bidrag til tidsskriftKonferenceabstrakt i tidsskriftForskningpeer review

Resumé

Radiation Dose to the Eye Lens: Does Positioning Really Matter?

C. Baun1, K. Falch1, K.D. Nielsen2, S. Shanmuganathan1, O. Gerke1, P.F. Høilund-Carlsen1 1Department of Nuclear Medicine, Odense University Hospital, Odense C, Denmark. 2University College Lillebaelt, Odense, Denmark.

Aim: The scan field in oncology patients undergoing eyes-to-thighs PET/CT must always include the base of the scull according to department guidelines. The eye lens is sensitive to radiation exposure and if possible it should be avoided to scan the eye. If the patient’s head is kipped backwards during the scan one might avoid including the eye in the CT scan without losing sufficient visualization of the scull base. The aim of this study was to evaluate the possibility of decreasing the radiation dose to the eye lens, simply by changing the head position, when doing the PET/CT scan from the base of the scull to the proximal femur. Methods and materials: The study was performed using a human like whole body phantom with electronic dosimetry units placed upon each eye to detect the exact radiation dose to the eye lens during each scan. The phantom’s head was placed in two different positions, (a) elevated with a small pillow below the head (standard), and (b) kipped backwards with the pillow below the neck (kipped). For each head position, CT scans were repeated 5 times with both a low dose and a high dose CT protocol; in this way, a total of 20 CT scans were performed. Robust standard errors were used in order to account for intragroup correlation due to repeated measurements. Results: Overall, position ‘kipped’ reduced the radiation dose to the eye lens, on average by 42.9% or in mean by 1.15 mSv (95% CI: 0.45-1.85; p=0.001) compared to ‘standard’, i.e., from 2.68 mSv (range 0.67 – 4.68) to 1.53 mSv (range 0.69 – 4.46). With the high dose protocol and position ‘kipped’, the radiation dose to the eye lens decreased by 41.5%, on average by 1.52 mSv (95% CI: 0.39-2.64; p=0.008) compared to ‘standard’, i.e., from 3.66 mSv (range 1.62 – 4.68) to 2.14 mSv (range 1.12 – 4.46). With the low dose protocol and position ‘kipped’, the decrease was comparable in relative terms: by 45.6% or, in absolute terms on average, 0.78 mSv, (95% CI: -0.05 to 1.61; p=0.07, i.e., from 1.71 mSv (range 0.67 – 2.97) to 0.93 mSv (range 0.69 – 1.66). Not in a single case had position 'kip' the effect that one could not overlook the skull base. Conclusion: These results indicate that it is possible to reduce the radiation dose to the eye lens without loss of diagnostic information in the scan by optimizing positioning of the head.
OriginalsprogEngelsk
ArtikelnummerOP190
TidsskriftEuropean Journal of Nuclear Medicine and Molecular Imaging
Vol/bind42
Udgave nummer1 Supplement
Sider (fra-til)80-81
Antal sider1
ISSN1619-7070
StatusUdgivet - 2015
Begivenhed28th Annual Congress of the European Association of Nuclear Medicine - Hamburg, Tyskland
Varighed: 10. okt. 201514. okt. 2015
Konferencens nummer: 28

Konference

Konference28th Annual Congress of the European Association of Nuclear Medicine
Nummer28
LandTyskland
ByHamburg
Periode10/10/201514/10/2015

Citer dette

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Radiation dose to the eye lens : does positioning really matter that much? / Baun, Christina; Falch Braas, Kirsten; D. Nielsen, Kamilla; Shanmuganathan, Sanusa; Gerke, Oke; Høilund-Carlsen, Poul Flemming.

I: European Journal of Nuclear Medicine and Molecular Imaging, Bind 42, Nr. 1 Supplement, OP190, 2015, s. 80-81.

Publikation: Bidrag til tidsskriftKonferenceabstrakt i tidsskriftForskningpeer review

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AU - Shanmuganathan, Sanusa

AU - Gerke, Oke

AU - Høilund-Carlsen, Poul Flemming

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