Radiation dose of the lens in trans-sphenoidal pituitary surgery: pros and cons of a conventional setup using fluoroscopic guidance and CT-based neuronavigation.
OBJECTIVE
We determined the radiation dose in patients' lenses during pituitary surgery with either conventional fluoroscopy or CT-guided neuronavigation.


METHODS
Thermoluminescent dosimeters (TLD-100H) were attached to the lenses of an anthropomorphic Alderson-Rando head phantom. Simulation of the conventional setup of continuous fluoroscopy (61 kV peak, 2.01 mAs) with collimation and automatic exposure control was used with 1 TLD being removed every 5 seconds, followed by another experiment with 1 being removed every 30 seconds. For CT-guided neuronavigation, a spiral of 3-mm-thick sections without gap was performed (140 kV, 220 mA). Patients' charts (n = 87) were reviewed in terms of radiation exposure and perioperative complications.


RESULTS
Radiation dose is distance-dependent (P < .002), with an exposure-time-dependent linear increase (R(2) = 99.27, P < .0001) close to the primary beam only. The radiation dose of the CT (mean, 39.39 mGy) was fivefold higher compared with the maximal time of 3 minutes (8 mGy) reached in our patients by using the conventional setup. CT offers more detailed 3D anatomy available at any time intraoperatively. Tolerance doses needed to develop cataracts were not reached, and perioperative complications occurred without significant differences (Mann-Whitney U test, P = .39) using either method. Continuous use of fluoroscopy reached the mean value of CT after 14.33 minutes.


CONCLUSIONS
Neuronavigation provides better anatomic information and avoids repetitive exposure and accumulation to the staff, with the disadvantage of an increased radiation exposure to the patient causing at least no acute harm. Long-term effects are hard to prove but cannot be neglected either.
Ulmer
S
S
Section of Neuroradiology, Department of Neurosurgery, University Hospital of Schleswig-Holstein, Kiel, Germany. ulmer@email.com
Schulz
E
E
Moeller
B
B
Krause
U R
UR
Nabavi
A
A
Mehdorn
H M
HM
Jansen
O
O
D003198:Computer Simulation; D005471:Fluoroscopy; D006801:Humans; D007908:Lens, Crystalline / Q000528:radiation effects*; D008962:Models, Theoretical; D038361:Neuronavigation / Q000379:methods*; D019635:Neurosurgical Procedures; D019047:Phantoms, Imaging; D010902:Pituitary Gland / Q000601:surgery*; D011829:Radiation Dosage; D013100:Sphenoid Bone / Q000601:surgery; D025321:Surgery, Computer-Assisted; D014057:Tomography, X-Ray Computed