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.
|Tidsskrift||European Journal of Nuclear Medicine and Molecular Imaging|
|Udgave nummer||1 Supplement|
|Status||Udgivet - 2015|
|Begivenhed||28th Annual Congress of the European Association of Nuclear Medicine - Hamburg, Tyskland|
Varighed: 10. okt. 2015 → 14. okt. 2015
Konferencens nummer: 28
|Konference||28th Annual Congress of the European Association of Nuclear Medicine|
|Periode||10/10/2015 → 14/10/2015|
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 tidsskrift › Konferenceabstrakt i tidsskrift › Forskning › peer review
TY - ABST
T1 - Radiation dose to the eye lens
T2 - does positioning really matter that much?
AU - Baun, Christina
AU - Falch Braas, Kirsten
AU - D. Nielsen, Kamilla
AU - Shanmuganathan, Sanusa
AU - Gerke, Oke
AU - Høilund-Carlsen, Poul Flemming
PY - 2015
Y1 - 2015
M3 - Conference abstract in journal
VL - 42
SP - 80
EP - 81
JO - European Journal of Nuclear Medicine and Molecular Imaging
JF - European Journal of Nuclear Medicine and Molecular Imaging
SN - 1619-7070
IS - 1 Supplement
M1 - OP190