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cavernous sinus TVE 5 58/ F glomus jugulare tumor TAE 6 38/M brain AVM (grade II) TAE 7 49/ F dural A VF of the cavernous sinus TVE 8 57/ F dural AVF of the cavernous sinus TVE 9 54/ F hemangioma of the face TAE 10 49/ F dural AVF of the cavernous sinus TVE 11 60/M dural AVF of the posterior fossa TAE 12 60/M dural AVF of the posterior fossa TVE 13 7 1/ F dural AVF of the cavernous sinus TVE 14 28/ M brain AVM (grade Ill) TAE 15 17/M traumatic aneurysm of superficial TAE temporal artery Note.- AVF indicates arteriovenous fistula; AVM, arteriovenous malformation; TAE, transarterial embolization; and TVE, transvenous embolization. tance between the x-ray tube and the image intensifier (7, 9, and 13 in variable) was fixed at 90 em, and the x-ray field was decreased to as small as possible. The fluoroscopic examination was performed in the continuous mode. In a lateral-view examination , the x-ray tube was almost always placed to the right side of the patient because of the design of our x-ray device. Digital subtraction angiography was always performed with manual injection of contrast medium and at the frame rate of 3 frames per second, and at each digital subtraction angiography examination a total of 15 to 25 frames were collected in most cases. The operator performed the endovascular procedure while seated on a chair at the right side of the patient. The local exposure dose was measured with thermoluminescence dosimeters (Kasei Optonix, Tokyo, Japan) composed of Mg2Si04 (Tb), each covered by a holder with a sensitivity compensation filter (holder F). The detection limits of this thermoluminescence dosimeter system are 0.1 mR and 100 R. The sensitivity of each thermoluminescence dosimeter and the thermoluminescence dosimeter reader were calibrated with a radiation source (radium226; Kasei Optonix), and residua l radiation energy of each thermoluminescence dosimeter was removed by placing it in an a nnealing oven (Kasei Optinix). Thermoluminescence dosimeters were attached to seven areas on the operator and five areas on the patient. The areas in the operator were glabella outside the spectacles, representing the eye lens, the midline of the neck inside and outside of the thyroid protector, the left shoulde r inside the protector, the ulnar a spect of the left upper arm, the back of the left hand, and the pubis. In the patients, thermoluminescence dosimeter were atta ched to the glabella, the right and left temporal a reas (a round the pterion), the midline of the neck, and the pubis. Immediately after the operation, each the rmoluminescence dosimeter was removed from the Holder-F, avoiding exposure to fluorescent light, and inserted into the thermoluminescence dosimeter reader AJNR: 15, November 1994 TABLE 2: Conversion coefficients from the radiation dose to the 70 ~-tm equivalent dose at each photon energy of X-ray source Photon Energy, keY f70 .,_ (Kyokko thermoluminescence dosimeter Reader 2500, Kasei Optonix) . The exposure dose was automatically calculated from the luminescent dose of the thermoluminescence dosimeter. The equivalent dose (H70,_..m, in millisieverts) of the skin was calculated by the formula: H70,_..m = f7o,_..m X fx70 X Px where f70 is a conversion factor from the Mm ' M m radiation dose to H70,_..m; fx70,_..m is a conversion factor from Px to the radiation dose; and Px is the dose measured by the thermoluminescence dosimeter reader for the areas other than the glabella . As shown in Table 2 , the coefficients 10.4 and 1.19 were used for f70,_..m and fx7 o,_..m, respectively, because the estimated effective photon energy of our x-ray device is about 30 keV. The equivalent dose (H3mm• in millisieverts) of the lens (eye) was calculated by the formula : H3mm = f3mm X fx3mm X Px,
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