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Radiation Exposure Levels During Spine Interventional Procedures: A Comparison Between Vertebroplasty and Kyphoplasty 2003

Rosioreanu A, Ortiz O, Natarajan V, Gregorius D, Koehler V, De Moura A, Luchs JS
Winthrop-University Hospital
Mineola, N.Y.

Purpose:
To determine and compare the differences in radiation exposure to the interventional spine radiologist during vertebroplasty as compared to kyphoplasty.

Methods:
A prospective collection of data was obtained during 10 vertebroplasty and 10 kyphoplasty procedures performed in the thoracic and lumbar spine by an experienced neuroradiologist. Bi-plane fluoroscopy was used to perform all of the procedures. A bilateral transpedicular approach was utilized in all cases. The same types of radiation shielding devices were used in all of the cases and the device position was kept constant for all cases. Pulsed fluoroscopy was utilized in all procedures, with pulse 1 (7.5 pulses/sec) fluoroscopy used during needle positioning and pulse 2 (15 pulses/sec) used for the cement delivery portion of the procedure. Radiation exposure to the operator was measured using an electronic pocket dosimeter (Aloka Co., Ltd.) and radiation exposure rate (mR/hr) was monitored using a handheld ionization chamber (Victoreen, model 470A). The pocket dosimeter was placed in the operators left vest pocket, in all cases the side closest to the fluoroscopy unit. An injection device (EZ Flow CDS, ArthroCare Corporation) was used for vertebroplasty procedures and the Kyphon kit (Kyphon Co.) was used for all of the kyphoplasty procedures. A bilateral, transpedicular approach was used for all procedures. Each procedure was divided into needle positioning time and exposure for a specific vertebral level, as well as cement delivery time and exposure for that same level. The exposure times during each procedure and doses received by the interventionalist were recorded.

Results:
The average time for fluoroscopy during vertebroplasty was 11.2 minutes, which included an average of 5.2 minutes of needle positioning time and 6.0 minutes of cement delivery time. The average radiation exposure reading was 48.9 micro-Sieverts for the entire vertebroplasty procedure. This included an average of 21.2 micro-Sieverts of exposure during needle positioning and 27.7 micro-Sieverts of exposure during cement delivery. The average fluoroscopy time for kyphoplasty was 13.2 minutes, which included an average of 8.5 minutes for needle positioning and 4.7 minutes for cement delivery. The average radiation exposure reading during the kyphoplasty procedure was 226.5 micro-Sieverts for the entire kyphoplasty procedure. This included an average of 105.7 micro-Sieverts of exposure during needle positioning and 120.8 micro-Sieverts during cement delivery. The difference in total radiation exposure level between vertebroplasty and kyphoplasty was statistically significant (p<0.01; Student’s t-test).

Conclusion:
With respect to radiation, operator exposure rates for kyphoplasty are significantly higher than those observed with vertebroplasty. The two major factors which contribute to this phenomena are increased procedure and fluoroscopy time associated with kyphoplasty as well as the closer proximity to the fluoroscopy unit that is required when using the handheld drill and bone filler devices in kyphoplasty.

References:

1. Mathis JM, Barr JD, Belkoff SM, et al. Percutaneous vertebroplasty: A developing standard of care for vertebral compression fractures. AJNR Am J Neuroradiol 2001; 22:373-381
2. Wong WH, Olan WJ, Belkoff SM. Balloon kyphoplasty, in Mathis JM, Deramond H, Belkoff SM (eds): Percutaneous Vertebroplasty. New York, Springer-Verlag, pp 109-124, 2002