National dose reference levels in computed tomography-guided interventional procedures-a proposal.

OBJECTIVES: To establish national reference levels (RLs) in interventional procedures under CT guidance as required by the 2013/59/Euratom European Directive. METHODS: Seventeen categories of interventional procedures in thoracic, abdominopelvic, and osteoarticular specialties (percutaneous infiltration, vertebroplasty, biopsy, drainage, tumor destruction) were analyzed. Total dose length product (DLP), number of helical acquisitions (NH), and total DLP for helical, sequential, or fluoroscopic acquisitions were recorded for 10 to 20 patients per procedure at each center. RLs were calculated as the 3rd quartiles of the distributions and target values for optimization process (TVOs) as the median. RLs and TVOs were compared with previously published studies. RESULTS: Results on 5001 procedures from 49 centers confirmed the great variability in patient dose for the same category of procedures. RLs were proposed for the DLPs and NHs in the seventeen categories. RLs in terms of DLP and NH were 375 mGy.cm and 2 NH for spinal or peri-spinal infiltration, 1630 mGy.cm and 3 NH for vertebroplasty, 845 mGy.cm and 4 NH for biopsy, 1950 mGy.cm and 8 NH for destruction of tumors, and 1090 mGy.cm and 5 NH for drainage. DLP and NH increased with the complexity of procedures. CONCLUSIONS: This study was the first nationwide multicentric survey to propose RLs for interventional procedures under CT guidance. Heterogeneity of practice in centers were found with different levels of patient doses for the same procedure. The proposed RLs will allow imaging departments to benchmark their practice with others and optimize their protocols. KEY POINTS: • National reference levels are proposed for 17 categories of interventional procedures under CT guidance. • Reference levels are useful for benchmarking practices and optimizing protocols. • Reference levels are proposed for dose length product and the number of helical acquisitions.

Radiation Exposure During Transarterial Chemoembolization: Angio-CT Versus Cone-Beam CT.

INTRODUCTION: Cone-beam computed tomography (CBCT) has been developed to improve reliability of many interventional radiology (IR) procedures performed with Angio system, such as transarterial chemoembolization (TACE). Angio-CT has emerged as a new imaging technology that combines a CT scanner with an Angio system in the same IR suite. The purpose of our study was to compare Angio system with CBCT capability and Angio-CT in terms of patient radiation exposure during TACE procedures. MATERIALS AND METHODS: Consecutive TACE procedures performed between January 2016 and September 2017 with the two imaging modalities (Artis Zeego defining the CBCT group and Infinix-i 4D-CT defining the Angio-CT group) were reviewed. TACE and patient's characteristics and patient radiation exposure parameters were collected. Dose-area products (DAP) and dose-length products (DLP) were converted into effective doses (ED) using conversion factors. Accuracy of tumor targeting and response was retrospectively assessed. RESULTS: A total of 114 TACE procedures in 96 patients were included with 57 procedures in each group. The total ED in the Angio-CT group was 2.5 times lower than that in the CBCT group (median 15.4 vs. 39.2 mSv, p < 0.001). Both 2D ED and 3D ED were lower in the Angio-CT group than in the CBCT group (5.1 vs. 20 mSv, p < 0.001, and 7.4 vs. 17.9 mSv, p < 0.001, respectively). There was no significant difference neither in terms of classes of tumor targeting (p = 0.509) nor in terms of classes of tumor response (p = 0.070) between both groups. CONCLUSION: Angio-CT provides significant decrease in patient effective dose during TACE procedures compared to Angio system with CBCT.

Synthesis of O-1- O-6 Substituted Positional Isomers of d-Glucose-Thioether Ligands and Their Ruthenium Polypyridyl Conjugates.

A library of positional isomers of d-glucose ( O-1- O-6) as ligands and their 11 light-active ruthenium conjugates has been synthesized. A protecting group strategy without the necessity of using palladium on carbon for the modification for the 2- O and 4- O position allows for the incorporation of sulfur donor atoms as ligands for transition metal complexes.

Surgeon's and patient's radiation exposure during percutaneous thoraco-lumbar pedicle screw fixation: A prospective multicenter study of 100 cases.

HYPOTHESIS: Percutaneous pedicle screw fixations (PPSF) are increasingly used in spine surgery, minimizing morbidity through less muscle breakdown but at the cost of intraoperative fluoroscopic guidance that generates high radiation exposure. Few studies have been conducted to measure them accurately. MATERIAL AND METHODS: The objective of our study is to quantify, during a PPSF carried out in different experimented centers respecting current radiation protection recommendations, this irradiation at the level of the surgeon and the patient. We have prospectively included 100 FPVP procedures for which we have collected radiation doses from the main operator. For each procedure, the doses of whole-body radiation, lens and extremities were measured. RESULTS: Our results show a mean whole body, extremity and lens exposure dose per procedure reaching 1.7±2.8µSv, 204.7±260.9µSv and 30.5±25.9µSv, respectively. According to these values, the exposure of the surgeon's extremities and lens will exceed the annual limit allowed by the International Commission on Radiological Protection (ICRP) after 2440 and 4840 procedures respectively. CONCLUSION: Recent European guidelines will reduce the maximum annual exposure dose from 150 to 20mSv. The number of surgical procedures to not reach the eye threshold, according to our results, should not exceed 645 procedures per year. Pending the democratization of neuronavigation systems, the use of conventional fluoroscopy exposes the eyes in the first place. Therefore they must be protected by leaded glasses. LEVEL OF PROOF: IV, case series.

Surgeon's and Patient's Radiation Exposure Through Vertebral Body Cement Augmentation Procedures: A Prospective Multicentric Study of 49 Cases.

OBJECTIVE: Vertebral body cement augmentation as a treatment option for osteoporotic or traumatic fractures has become increasingly popular during the past decade. However, these surgical procedures require numerous fluoroscopic examinations, resulting in high radiation exposure for the patient and the surgical team. The aim of this study was to evaluate the level of radiation exposure of the spine surgeon and the patient during these percutaneous procedures. METHODS: Forty-nine patients admitted for single- or 2-level vertebral compression fracture were prospectively included and treated with vertebral body cement augmentation. For each procedure, radiation dose was measured on the surgeon's whole body, lens, and extremities as well as patient irradiation. Each surgeon wore 2 thermoluminescent dosimeters to measure lens and extremities radiation exposure and 1 electronic personal dosimeter. Patient clinical and surgical data, effective dose to patient, and surgeon were analyzed. RESULTS: Mean operative time was 31.5 ± 11.7 minutes. The average fluoroscopic time was 61.0 ± 27.1 seconds. The average whole-body radiation dose per procedure was 1.4 ± 2.1 µSv. The average equivalent dose to lens and extremities were 44 µSv and 59 µSv, respectively. CONCLUSIONS: Values of radiation doses for surgeon and patient were lower than those reported in the previous literature. The recommended annual dose limit is set to 500 mSv for extremities and 150 mSv for lens. According to our results, the exposure dose to the eye exceeds the annual limit after 3500 procedures. However, there is increasing concern among surgeons about radiation exposure, and there is still a need for solutions as preventive measures.

Assessment of the Radiation Exposure of Surgeons and Patients During a Lumbar Microdiskectomy and a Cervical Microdiskectomy: A French Prospective Multicenter Study.

OBJECTIVE: Cervical and lumbar disk herniations are the most frequently carried out procedures in spinal surgery. Often, a few snapshots during the procedure are necessary to validate the level or to position the implant. The objective of this study is to quantitatively estimate the radiation received by a spine surgeon and patient during a low-dose radiation procedure. METHODS: We conducted a prospective multicenter study in France from November 2014 to April 2015. Four spine centers were monitored for radiation received by surgeons during interventions for lumbar disk herniation and cervical disk herniation. RESULTS: A total of 134 patients were included. For lumbar disk herniation, the average exposure for the surgeon was 0.584 µSv on the chest, 5.291 µSv on the lens, and 9.295 µSv on the hands per procedure. For these procedures, the dose area product (DAP) was 94.2 ± 198.4 cGy·cm(2), and the fluoroscopic time was 10.2 ± 16.9 seconds. For a herniated cervical disk, the average exposure for the surgeon was 0.122 µSv on the chest, 3.106 µSv on the lens, and 7.143 µSv on the hands per procedure. For these procedures, the DAP was 35.7 ± 72.1 cGy·cm(2), and the fluoroscopic time was 19.7 ± 13.7 seconds. CONCLUSIONS: Exposure to x-rays for surgeons and patients during surgery for lumbar disk herniation is higher than during surgery for cervical herniation disk. Our results show that radiation exposure to the spine surgeon is still far below the annual dose limits.