The PV procedure requires radiographic navigation in two planes (anteroposterior and lateral views) to identify the entry point for insertion of the spinal needle on the index vertebral pedicle(s). Furthermore, real-time fluoroscopic monitoring is usually recommended during cement injection during PV. With the popularity of PV, this technique draws concern regarding radiation exposure to the patient and operator. Several studies have investigated the radiation exposure during PV and found that the radiation-related risk may be considerable
[6–9]. The National council in Radiation Protection and Measurements in 1993 suggested that the occupational exposure limits for extremity (eg. Hands) is 500 mSv/y, for the eye is 150 mSv/y, and for the total dose (whole body) is 50 mSv/y
. In our study, the whole body dose without protection is 0.27 and 0.25 mSv for the one-fluoroscopic technique and two-fluoroscopic technique, respectively. Therefore, if an operator did not wear the lead apron for shielding, the total exposure dose (whole body) will exceed the annual limit after 200 single-level vertebroplasty procedures annually regardless of one or two-fluoroscopic techniques. According to Mroz's study
, the whole body dose (0.248 mSv/vertebra) to the operator during kyphoplasty is similar to that of our study. They also measured the exposure doses to the hand and concluded that the exposure dose to the hand would exceed the annual limit after 300 levels of kyphoplasty. Therefore they recommend the operator should always consider the appropriate protection (eg. lead gloves) against the radiation exposure to the hands. However, Wagner
 et al. evaluated 4 different type protective gloves and reported a large variation in radiation attenuation from exposure reduction of 7% to almost 50%. So that, even though wearing protective gloves, the operator should place his or her hand as away from the path of the radiation beam as possible.
The PV technique has rapidly evolved since Galibert performed the first PV in France in 1984
. With respect to radiographic guidance, one-fluoroscopic technique or combined CT and fluoroscopic guidance were usually used to monitor PV
. We reported that the two-fluoroscopic technique
 provides concurrent, real-time AP and lateral radiographic views and can reduce the operative time for PV. The technique is also more convenient since it allows the operator to take both AP and lateral projections without turning the C-arm. Mehdizade
 et al. used biplane fluoroscopy unit to monitor vertebroplasty, which was similar to two-fluoroscopic technique in our study. They reported that the exposure doses to the operator were 0.022-3.256 mGy with the TLD outside and 0.01-0.47 mGy inside the lead apron. Those data seems to be comparable to our measurements as 0.11-0.39 mSv (0.25 ± 0.14 mSv) with two-fluoroscopic technique. However, we did not know the average dose in their study. Fitousi
 et al. reported that the occupational exposure to the operator was 0.011 mGy in effective dose, 0.328 mGy in eye dose and 1.861 mGy in hand dose, during vertebroplasty with continuous fluoroscopy (Philips DVIS 3000). By using mobile shielding devices (eg. lead sheet), they found that the effective dose to the operator can be reduced by more than 75%.
 et al. evaluated the radiation exposure time (ET) of kyphoplasty using the two-fluoroscopic technique and reported that the ET was shorter compared to other studies using the one fluoroscopic technique
. Instead of ET, we evaluated radiation dose to the patient and found that the average dose (1.97 mSv) with the one-fluoroscopic technique was significantly higher compared to the dose measured during the two-fluoroscopic technique (0.95 mSv), P = 0.031. We agree with Boszczyk’s comment that once an optimal setting for the two-fluoroscopic technique has been found, it is maintained throughout the procedure and no radiation is “wasted” during readjustment for the other plane film. Furthermore, in the current study, the mean operative time using the two-fluoroscopic technique was shorter than that found using the one-fluoroscopic technique. The reduced operative time with the two-fluoroscopic technique may have resulted from the time saved by not having to readjust the C-arm to the other plane compared to the time used during the one-fluoroscopic technique in readjusting the X-ray generator to the appropriate position.
In our study, the exposure doses to the patient are significantly different (P = 0.031) between using one-fluoroscopic and two-fluoroscopic technique. However, the doses to the operator are not different statistically. The dosimeter on the operator is mainly exposed to the scatter radiation, while that on the patient is partly exposed to primary radiation. Therefore, the dose amount on the operator is less than that on the patient (1.97, 0.95 mSv to patient Vs.0.27, 0.25 mSv to operator). Probably, for the small dose amount to the operator, we need large sample size to prove the doses to the operator different between the two techniques, if any.
The mean radiation dose to the operator per PV level was lower compared with Kruger’s report, whether the one-fluoroscopic (0.27 mSv) or the two-fluoroscopic technique (0.25 mSv) was used in the current study
. They assessed 36 PV procedures using the two-fluoroscopic technique. The average whole body dose (at the level of the operator’s chest) per vertebra was 1.44 mSv. Several different fluoroscopic modes were evaluated in their study: continuous fluoroscopy, high-level fluoroscopy and pulsed fluoroscopy. We agreed with their conclusions regarding the pulsed mode and we used the pulsed fluoroscopic mode. We found that it provided adequate cement image quality while limiting radiation exposure for the majority of patients undergoing PV.
Instead of continuous imaging, we used intermittent imaging at every 2–3 turns of syringe compressor (0.2 ml/turn) during PV, not only to localize the entry point, but also during cement delivery
. In the current study, the use of intermittent imaging may decrease radiation dose, as compared with the use of continuous imaging. However, we consider blind deposition of cement to be potentially dangerous between images, therefore, we took an image at only one turn of the syringe compressor whenever cement was close to the posterior wall of the vertebral body. We stopped any procedure involving cement delivery if cement reached the posterior vertebral wall or entered the paravertebral veins.
Our study had several limitations. Our sample size was small although there was a significant difference in radiation dose to the patients between the two groups. Second, theoretically, the radiation dose positively correlates with radiation exposure time. We did not measure the radiation exposure time and were not able to conclude whether or not the decreased radiation dose, using the two-fluoroscopic technique, resulted from the shorter radiation exposure time.