Artikel
Radiation exposure to the lens in conventional transsphenoidal pituitary surgery compared to CT-guided neuronavigation
Strahlenexposition der Linse im Rahmen der konventionellen transsphenoidalen Hypohysenchirurgie verglichen mit der CT-gestützten Neuronavigation
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Autoren
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S. Ulmer
- Institut of Radiology, Lübeck
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E. Schulz
- Institut of Radiology, Lübeck
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U. Melchert
- Institut of Radiology, Lübeck
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U. R. Krause
- Department of Neurosurgery, Kiel
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A. Nabavi
- Department of Neurosurgery, Kiel
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M. H. Mehdorn
- Department of Neurosurgery, Kiel
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O. Jansen
- Section of Neuroradiology, Kiel
| Veröffentlicht: | 4. Mai 2005 |
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Gliederung
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Objective
We investigated the amount of radiation exposure applied during conventional pituitary surgery compared to a CT-based neuronavigation setup.
Methods
In pituitary surgery, the patient’s head is lightly overextended and positioned in the primary beam of a C-arm array (Philips BV 300, Philips, The Netherlands) focussed on the sella. In a new neuronavigation setup, a CT scan is performed (GE, High Speed Advantage) with 5 to 7 fiducial markers attached to the patient’s maxilla and forehead. The image stack (3mm slice thickness, 140KV, 220 mAs) covers the entire portion of the maxillary bone up to the apex. These data are transferred and used for intraoperative navigation. To estimate radiation exposure to the lens of the 70 randomized operated patients, we attached thermoluminescens dosimeters (TLDs) to a Rando Alderson head phantom in both settings. In the conventional setup one TLD was removed every 5 seconds while continuous radiation was performed up to 1 minute.
Results
Each TLD was displayed in two images of the CT scan. Radiation dosage increased in a linear fashion in the conventional setup up to 2.3 uGy after 1 minute of continuous radiation. Mean dosage of one TLD of the navigation setup was 39.4 uGy. None of our patients received more than 3 minutes of radiation in the conventional setup.
Conclusions
Even though CT has a distinctly higher radiation dosage, it offers more detailed information than the 2-dimensional X-ray and avoids the exposition of the surgeon to continuous and repeated intraoperative radiation. The dosage is far below thresholds causing catarcts to the lens (2 Gy/day in radiation therapy) and even though exposure to radiation should be used responsibly, CT navigation will do no harm to the patient.
