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The percutaneous placement or spinal cord stimulator electrode can cause excessive radiation levels for both the patient and the physician. The radiation exposure hazard is made worse by the fact that many C-arms have the capability for high level control fluoroscopy. Synonymous terms for high level control are: I) fluoro boost, 2) high contrast enhancement, and 3) low noise. The risk of excessive radiation exposure is best appreciated when one realizes that nine minutes of fluoroscopy at high level control is equivalent to a single fraction therapy dose used to treat basal cell carcinoma!
Measurements of scatter radiation were measured at five levels where the surgeon usually stands using a Keithley Model 36100 Ionization survey meter, a 20 cm thick polystyrene patient phantom in the beam and an OEC Diasonic C-arm set at 106 KVp and 3.3 mA with and without 1/8 inch thick lead drapes of two lengths.
Clinically significant reductions in scatter radiation (up to 99%) can be obtained by using lead shielding on the patient and from the table to the floor. (see table 1)
Table 1 Surgeons Exposure to Scatter Radiation (mR/HR)
Lead No Shielding Lead DrapesLead Drape A. Patient and 12″ below the table
Lead Drape B: Patient to floor
These objective measurements of scatter radiation demonstrate two things: I) the surgeon can be exposed to dangerous levels of scatter radiation when imaging an average size patient using typical radiographic technique. Be advised that the scatter will be higher as the radiation in the main beam increases. 2) Clinically significant reduction in radiation exposure to the surgeon is achieved by using lead shielding starting on the patient and extending to the floor.
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