Radiation exposure to operators during vertebroplasty

Comparison of operator and patient radiation exposure during fluoroscopy-guided vertebroplasty and kyphoplasty: a systematic review and meta-analysis

OBJECTIVE

Percutaneous vertebroplasty (PV) and balloon kyphoplasty (BK) are two minimally invasive techniques used to treat mechanical pain secondary to spinal compression fractures. A concern for both procedures is the radiation exposure incurred by both operators and patients. The authors conducted a systematic review of the available literature to examine differences in interventionalist radiation exposure between PV and BK and differences in patient radiation exposure between PV and BK.

METHODS

The authors conducted a search of the PubMed, Ovid Medline, Cochrane Reviews, Embase, and Web of Science databases according to the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines. Full-text articles in English describing one of the primary endpoints in ≥ 5 unique patients treated with PV or BK of the mobile spine were included. Estimates of mean operative time, radiation exposure, and fluoroscopy duration were reported as weighted averages. Additionally, annual occupational dose limits provided by the United States Nuclear Regulatory Commission (USNRC) were used to determine the number needed to harm (NNH).

RESULTS

The meta-analysis included 27 articles. For PV, the mean fluoroscopy times were 4.9 ± 3.3 minutes per level without protective measures and 5.2 ± 3.4 minutes with protective measures. The mean operator radiation exposures per level in mrem were 4.6 ± 5.4 at the eye, 7.8 ± 8.7 at the neck, 22.7 ± 62.4 at the torso, and 49.2 ± 62.2 at the hand without protective equipment and 0.3 ± 0.1 at the torso and 95.5 ± 162.5 at the hand with protection. The mean fluoroscopy times per level for BK were 6.1 ± 2.5 minutes without protective measures and 6.0 ± 3.2 minutes with such measures. The mean exposures were 31.3 ± 39.3, 19.7 ± 4.6, 31.8 ± 34.2, and 174.4 ± 117.3 mrem at the eye, neck, torso, and hand, respectively, without protection, and 1, 9.2 ± 26.2, and 187.7 ± 100.4 mrem at the neck, torso, and hand, respectively, with protective equipment. For protected procedures, radiation to the hand was the limiting factor and the NNH estimates were 524 ± 891 and 266 ± 142 for PV and BK, respectively. Patient exposure as measured by flank-mounted dosimeters, entrance skin dose, and dose area product demonstrated lower exposure with PV than BK (p < 0.01).

CONCLUSIONS

Operator radiation exposure is significantly decreased by the use of protective equipment. Radiation exposure to both the operator and patient is lower for PV than BK. NNH estimates suggest that radiation to the hand limits the number of procedures an operator can safely perform. In particular, radiation to the hand limits PV to 524 and BK to 266 procedures per year before surpassing the threshold set by the USNRC.

Robot-Assisted Bone Cement Injection

In this article, assistance to bone cement injection is studied, with a focus on vertebroplasty, a procedure dedicated to the treatment of vertebral compression fractures. A robotic system that can remotely be operated at pressures up to 140 bar is presented. It improves cement polymerization control, combining a cold passive exchanger that slows down the cement curing in the syringe and an active exchanger that controls the injected cement temperature. The cement remote injection uses a rate control teleoperation strategy with force feedback to help monitoring the cement state. In addition to laboratory assessments, cadaver experiments were performed to illustrate the satisfactory operation of the whole system.

Vertebral augmentation

Vertebral augmentation, including vertebroplasty and kyphoplasty, is a minimally invasive, image-guided procedure in which cement (typically polymethylmethacrylate (PMMA)) is injected into a vertebral body to treat painful fractures. The majority of vertebroplasty and kyphoplasty procedures are performed to treat symptomatic osteoporotic compression fractures refractory to conservative medical therapy; however, there is also evidence to suggest the benefits of augmentation in patients with refractory pain in the acute compression setting. The primary goal of augmentation is decreasing pain and improving a patient's functional status. The secondary goal of augmentation is vertebral body stabilization. This chapter outlines the indications, contraindications, techniques, and literature behind vertebral augmentation.

Fluoroscopic Cranial Radiation Exposure in Spine Surgery: A Prospective Single-Center Evaluation in Operating Room Personnel

Background

Cranial radiation exposure during instrumented spine surgery is not well documented. We set out to measure this risk to the patient, surgeon, surgical resident, and scrub technician during these procedures.

Methods

Forty-seven individuals were enrolled during a 1.5-year period between October 2014 and March 2016 at the University of New Mexico Department of Neurosurgery. Radiation doses were obtained through electronic dosimeters placed on the surgical cap over the temporal scalp (bilaterally on surgeon and resident assist, unilaterally on surgical scrub on the side facing radiation source) and on the midline of the patient's exposed cranium.

Results

Of the 47 procedures, 39 (83%) were open and 8 (17%) were minimally invasive or percutaneous instrumented procedures. A total of 91 motion segments were treated, with a mean of 1.9 levels per case (57% lumbosacral, 34% cervical, and 2.1% thoracic). Total fluoroscopic time was 12.9 minutes. Mean dose per case (mrem/case) was calculated for the spine surgeon (1.4), resident assist (1.4), surgical scrub (1.2), and the patient (3.6). All doses were within federal safety guidelines. A spine surgeon would need to perform more than 1400 cases per year to reach the current federal maximum permissible dose for head exposure.

Conclusions

There was no difference in cranial radiation exposure between operating room staff during spine surgeries. Moreover, the doses measured at the cranium were within national safety limits. Current protective technologies have significantly reduced the amount of ionizing radiation exposure during routine spine procedures; however, changes in behavior or equipment may further reduce radiation exposure to health care workers.

Clinical Relevance

Radiation exposure to patients and hospital staff remains a major concern in the practice of modern spine surgery. Cranial exposure remains the only established environmental risk factor for brain tumors, such as gliomas and meningiomas. Our study shows that all those exposed to radiation during spine surgery had cranial doses well within the national safety limits.

Radiation Exposure of Interventional Radiologists During Computed Tomography Fluoroscopy-Guided Renal Cryoablation and Lung Radiofrequency Ablation: Direct Measurement in a Clinical Setting

INTRODUCTION

Computed tomography (CT) fluoroscopy-guided renal cryoablation and lung radiofrequency ablation (RFA) have received increasing attention as promising cancer therapies. Although radiation exposure of interventional radiologists during these procedures is an important concern, data on operator exposure are lacking.

MATERIALS AND METHODS

Radiation dose to interventional radiologists during CT fluoroscopy-guided renal cryoablation (n = 20) and lung RFA (n = 20) was measured prospectively in a clinical setting. Effective dose to the operator was calculated from the 1-cm dose equivalent measured on the neck outside the lead apron, and on the left chest inside the lead apron, using electronic dosimeters. Equivalent dose to the operator's finger skin was measured using thermoluminescent dosimeter rings.

RESULTS

The mean (median) effective dose to the operator per procedure was 6.05 (4.52) μSv during renal cryoablation and 0.74 (0.55) μSv during lung RFA. The mean (median) equivalent dose to the operator's finger skin per procedure was 2.1 (2.1) mSv during renal cryoablation, and 0.3 (0.3) mSv during lung RFA.

CONCLUSION

Radiation dose to interventional radiologists during renal cryoablation and lung RFA were at an acceptable level, and in line with recommended dose limits for occupational radiation exposure.

Percutaneous vertebroplasty with the rotational fluoroscopy imaging technique

OBJECTIVE

To evaluate the feasibility of the rotational angiography unit (RAU) as a single technique to guide percutaneous vertebroplasty (PVP).

MATERIALS AND METHODS

Twenty-five consecutive patients (35 vertebral bodies, 20 lumbar and 15 thoracic) were treated using RA fluoroscopy. Using a state-of-the-art flat-panel angiographer (Artis zee, Siemens, Erlangen, Germany), rotational acquisitions were obtained in all patients for immediate post-procedure 2D/3D reconstructions. Pre- and postoperative back pain was assessed with the visual analog scale (VAS). Fluoroscopy time, patient radiation dose exposure, technical success, mean procedure time, mean number of rotational acquisitions and procedural complications were recorded. All features were compared with a historical cohort of patients (N = 25) who underwent PVP under CT and mobile C-arm fluoroscopy guidance.

RESULTS

In all cases, safe and accurate control of the needle insertion and bone-cement injection was successfully obtained with high-quality fluoroscopy images. One cement leakage was detected in the RAU group, and two leakages were detected in the CT and C-arm fluoroscopy group. Technical features were significantly different between the two groups (RAU vs. CT): mean procedure time: 38.2 min vs. 60.2 min (p = 0.02); median fluoroscopy time: 14.58 and 4.58 min (p = 0.02); median number of rotational acquisitions: 5 vs. 10 (p = 0.02); mean patient dose: 6 ± 1.3 mSv vs. 23 ± 1.3 mSv (p = 0.02). There were minor complications (pain, small hematoma) in two patients (8%) in the study group and three cases (12%) in the control group.

CONCLUSION

RAU guidance is an effective and safe technique for performing PVP because it reduces the procedural time and radiation exposure.

Evaluation of the impact of a system for real-time visualisation of occupational radiation dose rate during fluoroscopically guided procedures

Optimisation of radiological protection for operators working with fluoroscopically guided procedures has to be performed during the procedure, under varying and difficult conditions. The aim of the present study was to evaluate the impact of a system for real-time visualisation of radiation dose rate on optimisation of occupational radiological protection in fluoroscopically guided procedures. Individual radiation dose measurements, using a system for real-time visualisation, were performed in a cardiology laboratory for three cardiologists and ten assisting nurses. Radiation doses collected when the radiation dose rates were not displayed to the staff were compared to radiation doses collected when the radiation dose rates were displayed. When the radiation dose rates were displayed to the staff, one cardiologist and the assisting nurses (as a group) significantly reduced their personal radiation doses. The median radiation dose (Hp(10)) per procedure decreased from 68 to 28 μSv (p = 0.003) for this cardiologist and from 4.3 to 2.5 μSv (p = 0.001) for the assisting nurses. The results of the present study indicate that a system for real-time visualisation of radiation dose rate may have a positive impact on optimisation of occupational radiological protection. In particular, this may affect the behaviour of staff members practising inadequate personal radiological protection.

Evaluation of operator radioprotection using a new injection device during vertebroplasty

This study aimed to evaluate the protection granted by a simple device (X'TENS(®), Thiebaud, France) and to provide operators with information on the performance of this new device, which has not yet been assessed. Our assumption is that this device efficiently reduces the radiation dose to the operator. In a prospective clinical study, the radiation dose the operator's hand receives has been assessed using a specific sensor (UNFOR Instrument). Each patient included in the study was to receive at least two injections of cement during the procedure. Exposure was measured with and without the range extender. The data collected were then processed using a Wilcoxon matched pairs test. During 14 interventions, 20 vertebrae were treated with both procedures. Eleven women and three men were included. Seven patients underwent vertebroplasty for metastatic lesions and seven for osteoporotic lesions, bone fractures or vertebral compressions. The average injection time was 1.35 minutes with the device and 1.20 without (p=0.75). The dose to the hand per ml injected was 111.37 vs. 166.91 (p<0.05). Theoretically, the protection granted by the range extender depends on the length of the device. Our results are consistent with the inverse-square law. However, the variations in our results indicate that a proper and rigorous use is mandatory for the device to be effective. Given that radioprotection during fluoroscopy procedures is a frequently raised issue, the need for information for a safer practice increases likewise.

Comparing radiation exposure during percutaneous vertebroplasty using one- vs. two-fluoroscopic technique

Background

Percutaneous vertebroplasty (PV) requires relatively lengthy fluoroscopic guidance, which might lead to substantial radiation exposure to patients or operators. The two-fluoroscopic technique (two-plane radiographs obtained using two fluoroscopes) during PV can provide simultaneous two-planar projections with reducing operative time. However, the two-fluoroscopic technique may expose the operator or patient to increased radiation dose. The aim of this study was to quantify the amount of radiation exposure to the patient or operator that occurs during PV using one- vs. two-fluoroscopic technique.

Methods

Two radiation dosimeters were placed on the right flank of each patient and on the upper sternum of each operator during 26 single-level PV procedures by one senior surgeon. The use of two-fluoroscopic technique (13 patients) and one-fluoroscopic technique (13 patients) were allocated in a consecutive and alternative manner. The operative time and mean radiation dose to each patient and operator were monitored and compared between groups.

Results

Mean radiation dose to the patient was 1.97 ± 1.20 mSv (95% CI, 0.71 to 3.23) for the one-fluoroscopic technique group vs. 0.95 ± 0.34 mSv (95% CI, 0.85 to 1.23) for the two-fluoroscopic technique group (P =0.031). Mean radiation dose to the operator was 0.27 ± 0.12 mSv (95% CI, 0.17–0.56) for the one-fluoroscopic technique group vs. 0.25 ± 0.14 mSv (95% CI, 0.06–0.44) for the two-fluoroscopic technique group (P = 0.653). The operative time was significantly different between groups: 47.15 ± 13.48 min (range, 20–75) for the one-fluoroscopic technique group vs. 36.62 ± 8.42 min (range, 21–50) for the two-fluoroscopic technique group (P =0.019).

Conclusion

Compared to the one-fluoroscopic technique, the two-fluoroscopic technique used during PV provides not only shorter operative times but also reduces the radiation exposure to the patient. There was no significant difference between the two techniques with regards to radiation exposure to the operator.

Radiation exposure to the spine surgeon in lumbar and thoracolumbar fusions with the use of an intraoperative computed tomographic 3-dimensional imaging system

STUDY DESIGN

A prospective clinical research article.

OBJECTIVE

The primary goals were to determine (1) radiation exposure to the spine surgeon with the use of an intraoperative 3-dimensional imaging system and (2) to define the safe distance from the computed tomographic scanner.

SUMMARY OF BACKGROUND

Intraoperative radiation exposure to the spinal surgeon has been assessed during 2-dimensional fluoroscopy but has not been investigated during intraoperative 3-dimensional imaging.

METHODS

Ten patients undergoing lumbar or thoracolumbar fusion were enrolled in a prospective trial to determine the radiation exposure to a spine surgeon standing in the substerile room, with the use of the O-ARM Imaging System (Medtronic, Memphis, TN). A thermolucent digital dosimeter was worn at chest level without a lead apron. Dosimeter readings and distance from the spine surgeon were recorded. RESULTS.: Average surgeon exposure was 44.22 ± 17.4 μrem (range: 17.71-70.76 μrem). The mean distance from the O-ARM was 4.56 ± .32 m, and the surgeon was exposed for an average of 19.6 ± 5.7 seconds (range: 8.05-28.7 s). The annual number of necessary procedures required to surpass the exposure limit, according to the data presented here, would be 113,071 operations using O-ARM. Hence, the number of necessary procedures for O-ARM use is predicted to be 1,130,710 annual procedures to reach the occupational exposure limits for extremity, skin, and all other organs and 339,213 procedures to reach the limits for the lens of eye.

CONCLUSION

Radiation exposure is minimal to the surgical team during routine use of the O-ARM imaging system. The number of procedures required to surpass occupational exposure limits is high if using appropriate distance from the O-ARM.

Occupational radiation doses to operators performing fluoroscopically-guided procedures

In the past 30 y, the numbers and types of fluoroscopically-guided (FG) procedures have increased dramatically. The objective of the present study is to provide estimated radiation doses to physician specialists, other than cardiologists, who perform FG procedures. The authors searched Medline to identify English-language journal articles reporting radiation exposures to these physicians. They then identified several primarily therapeutic FG procedures that met specific criteria: well-defined procedures for which there were at least five published reports of estimated radiation doses to the operator, procedures performed frequently in current medical practice, and inclusion of physicians from multiple medical specialties. These procedures were percutaneous nephrolithotomy (PCNL), vertebroplasty, orthopedic extremity nailing for treatment of fractures, biliary tract procedures, transjugular intrahepatic portosystemic shunt creation (TIPS), head/neck endovascular therapeutic procedures, and endoscopic retrograde cholangiopancreatography (ERCP). Radiation doses and other associated data were abstracted, and effective dose to operators was estimated. Operators received estimated doses per patient procedure equivalent to doses received by interventional cardiologists. The estimated effective dose per case ranged from 1.7-56 μSv for PCNL, 0.1-101 μSv for vertebroplasty, 2.5-88 μSv for orthopedic extremity nailing, 2.0-46 μSv for biliary tract procedures, 2.5-74 μSv for TIPS, 1.8-53 μSv for head/neck endovascular therapeutic procedures, and 0.2-49 μSv for ERCP. Overall, mean operator radiation dose per case measured over personal protective devices at different anatomic sites on the head and body ranged from 19-800 (median = 113) μSv at eye level, 6-1,180 (median = 75) μSv at the neck, and 2-1,600 (median = 302) μSv at the trunk. Operators' hands often received greater doses than the eyes, neck, or trunk. Large variations in operator doses suggest that optimizing procedure protocols and proper use of protective devices and shields might reduce occupational radiation dose substantially.

[Vertebroplasty and kyphoplasty under dual guidance (CT and fluoroscopy): radiation dose to radiologist. A comparative study]

OBJECTIVES

The goals of this study is to evaluate and compare the irradiation received by the practitioner when performing percutaneous vertebroplasty or kyphoplasty guided by CT and fluoroscopy, for precise anatomical sites.

METHODS

For each intervention, radiothermoluminescent dosimeters were carefully positioned on both orbitals, both hands, and both ankles of the practitioner.

RESULTS

Twenty-four vertebroplasties were performed in 18 patients and nine kyphoplasties on seven patients. The anatomical site that is most exposed to radiation is the right hand. The two other sites subjected to irradiation are the left hand and the left orbital. This study demonstrates a significant correlation between the irradiation dose and fluoroscopy duration, reflecting both the quantity of primary-beam radiation and backscattered radiation.

CONCLUSION

The radiation dose to radiologist is more important for kyphoplasty procedures than vertebroplasty.

Dual guidance (CT and fluoroscopy) vertebroplasty: radiation dose to radiologists. How much and where?

OBJECTIVE

The goal of this study was to evaluate the radiation received by the practitioner when performing percutaneous vertebroplasty guided by CT and fluoroscopy for specific anatomical sites: orbits, hands, ankles, and thorax (under lead-lined apron).

MATERIALS AND METHODS

Twenty-four vertebroplasties were performed on 18 patients.

RESULTS

The anatomical site that was most exposed to radiation was the right hand (0.37 mSv on average). This study demonstrates a significant correlation between the irradiation dose and fluoroscopy duration, reflecting both the quantity of primary-beam radiation and backscattered radiation. The right hand (P = 0.03), left hand (P = 0.02), and the left orbit (P < 0.0001) are the anatomical zones that are the most affected by the combination of these two types of radiation, with cumulative irradiation doses of 0.45, 0.2, and 0.14 mSv, respectively. There was a significant correlation between the patient weight and radiation of the left hand (P = 0.03), the left orbit (P = 0.03), and the thorax (P = 0.02), confirming the major influence of backscattered radiation.

CONCLUSIONS

The most irradiated anatomical sites limiting the number of interventions are the left orbit and the right hand.

Historical review of occupational exposures and cancer risks in medical radiation workers

Epidemiological studies of medical radiation workers have found excess risks of leukemia, skin and female breast cancer in those employed before 1950 but little consistent evidence of cancer risk increases subsequently. Occupational radiation-related dose-response data and recent and lifetime cancer risk data are limited for radiologists and radiologic technologists and lacking for physicians and technologists performing fluoroscopically guided procedures. Survey data demonstrate that occupational doses to radiologists and radiologic technologists have declined over time. Eighty mostly small studies of cardiologists and fewer studies of other physicians reveal that effective doses to physicians per interventional procedure vary by more than an order of magnitude. For medical radiation workers, there is an urgent need to expand the limited information on average annual, time-trend and organ doses from occupational radiation exposures and to assess lifetime cancer risks of these workers. For physicians and technologists performing interventional procedures, more information about occupational doses should be collected and long-term follow-up studies of cancer and other serious disease risks should be initiated. Such studies will help optimize standardized protocols for radiologic procedures, determine whether current radiation protection measures for medical radiation workers are adequate, provide guidance on cancer screening needs, and yield valuable insights on cancer risks associated with chronic radiation exposure.

Percutaneous vertebroplasty performed by the isocenter puncture method

PURPOSE

The aim of this study was to clarify the usefulness of the isocenter puncture (ISOP) method.

MATERIALS AND METHODS

We investigated 73 vertebral bodies that had undergone percutaneous vertebroplasty (PVP) by the ISOP method, 118 vertebral bodies that had undergone the puncture simulation method, and 33 vertebral bodies that had undergone the conventional method. The items to be examined included the success rate (SR) of the median puncture of the vertebral body and the procedure time. The puncture accuracy and fluoroscopy time were also measured for the ISOP method.

RESULTS

The SR was significantly higher and the procedure time significantly shorter when using the ISOP method rather than the conventional method. However, no significant differences were observed between the ISOP method and the puncture simulation method. The errors between the puncture needle tip and the puncture target point in the ISOP method were an average of 1.52, 2.08, and 1.87 mm in each of the horizontal, ventrodorsal, and craniocaudal directions. The fluoroscopy time when operating on one vertebral body was an average of 5.8 min.

CONCLUSION

The ISOP method is considered to be a useful approach while also reducing the puncture time and the fluoroscopy time.