George Papadokostakis

Occupational exposure from common fluoroscopic projections used in orthopaedic surgery

BACKGROUND Personnel assisting in or performing fluoroscopically guided procedures may be exposed to high doses of radiation. Accurate occupational dosimetric data for the orthopaedic theater staff are of paramount importance for practicing radiation safety. METHODS Fluoroscopic screening was performed on an anthropomorphic phantom with use of four projections common in image-guided orthopaedic surgery. The simulated projections were categorized, according to the imaged anatomic area and the beam orientation, as (1) hip joint posterior-anterior, (2) hip joint lateral cross-table 45 degrees, (3) lumbar spine anterior-posterior, and (4) lumbar spine lateral 90 degrees. The scattered air kerma rate was measured on a grid surrounding the operating table. For each grid point, the effective dose, eye lens dose, and face skin dose values, normalized over the tube dose area product, were derived. For the effective dose calculations, three radiation protection conditions were considered: (1) with the exposed personnel using no protection measures, (2) with the exposed personnel wearing a 0.5-mm lead-equivalent protective apron, and (3) with the exposed personnel wearing both an apron and a thyroid collar. Maximum permissible workloads for typical hip, spine, and kyphoplasty procedures were derived on the basis of compliance with effective dose, eye lens dose, and skin dose limits. RESULTS We found that the effective dose, eye lens dose, and face skin dose to an orthopaedic surgeon wearing a 0.5-mm lead-equivalent apron will not exceed the corresponding limits if the dose area product of the fluoroscopically guided procedure is <0.38 Gy m (2). When protective eye goggles are also worn, the maximum permissible dose area product increases to 0.70 Gy m (2), while the additional use of a thyroid shield allows a workload of 1.20 Gy m (2). The effective dose to the orthopaedic surgeon working tableside during a typical hip, spine, kyphoplasty procedure was 5.1, 21, and 250 micro Sv, respectively, when a 0.5-mm lead-equivalent apron alone was used. The additional use of a thyroid shield reduced the effective dose to 2.4, 8.4, and 96 micro Sv per typical hip, spine, and kyphoplasty procedure, respectively. CONCLUSIONS The levels of occupational exposure vary considerably with the type of fluoroscopically assisted procedure, staff positioning, and the radiation protection measures used. The data presented in the current study will allow for accurate estimation of the occupational dose to orthopaedic theater personnel.

Estimation of Patient Dose and Associated Radiogenic Risks From Fluoroscopically Guided Pedicle Screw Insertion

Study Design. An experimental model for the assessment of patient dose and associated radiogenic risks associated with pedicle screw internal fixation surgical procedures. Objectives. To provide data for the accurate determination of patient effective dose, gonadal dose, and entrance skin dose from fluoroscopically assisted pedicle screw insertion procedures and to investigate the potential of both stochastic and deterministic radiogenic effects to occur following such procedures. Summary of Background Data. There is increased concern on radiation exposure of patients undergoing fluoroscopically guided interventional procedures. Methods. The cumulative screening time and dose area product, for each fluoroscopic projection used, were monitored in 20 patients undergoing pedicle screw internal fixation. The dose absorbed by each radiosensitive organ/tissue was determined from direct measurements obtained using an anthropomorphic phantom appropriately loaded with thermoluminescence dosimeters. Results. An average pedicle screw insertion procedure requires 1.2 minutes and 2.1 minutes of fluoroscopic exposure along anteroposterior and lateral projections, respectively, resulting in a dose area product of 232 cGy cm2 and 568 cGy cm2, correspondingly. Gender-specific normalized data for the determination of effective, gonadal, and entrance skin dose to patients undergoing fluoroscopically guided pedicle screw internal fixation procedures were derived. The effective dose from an average procedure was 1.52 and 1.40 mSv and the gonadal dose 0.67 and 0.12 mGy for female and male patients, respectively. The average radiogenic risks for fatal cancer and genetic defects were 115 and 4 per million of patients treated, respectively. Induction of skin injuries might be induced when fluoroscopy along the lateral projection is highly extended and the source to skin distance is kept low. Conclusions. Patient dose and radiogenic risks associated with an average pedicle screw internal fixation procedure are tolerable. However, for young patients with complex spinal disorders requiring extended fluoroscopy, radiogenic risks may be considerable. Present data may beused for estimation of effective dose, gonadal dose, and entrance skin exposure and associated radiogenic risks to patients undergoing fluoroscopically guided pedicle screw insertion in any institution.

Ultrasound velocity through the cortex of phalanges, radius, and tibia in normal and osteoporotic postmenopausal women using a new multisite quantitative ultrasound device.

Damilakis J, Papadokostakis G, Vrahoriti H, et al. Ultrasound velocity through the cortex of phalanges, radius, and tibia in normal and osteoporotic postmenopausal women using a new multisite quantitative ultrasound device. Invest Radiol 2003;38:207–211. Rationale and Objectives.To assess a new multisite quantitative ultrasound (QUS) device (Sunlight Omnisense 7000 S) suitable for the measurement of speed of sound (SOS) in the phalanges, radius, and tibia. Methods.The study group consisted of 270 healthy Caucasian postmenopausal patients (mean age: 60.0 ± 7.6 years) and 53 Caucasian postmenopausal patients (mean age: 67.2 ± 7.4 years) with osteoporotic fractures. Measurements of SOS and bone mineral density (BMD) were carried out in all subjects. Results.Intraobserver in vivo short-term precision was on average 0.76% for the radius, 0.47% for the tibia, and 1.54% for the phalanges. The interobserver precision ranged from 0.77% to 2.39%. Measurements of SOS at the 3 skeletal sites were significantly correlated (r = 0.28–0.44;P < 0.001). Significant correlations were found between SOS at all sites and BMD (r = 0.21–0.41;P < 0.001). The odds ratio for fracture prediction for SOS was 1.47 for tibia, 1.69 for radius, and 2.69 for phalanx. The corresponding odds ratios for BMD at the lumbar spine, femoral neck, and total hip ranged from 2.08 to 3.26. The area under the receiver operating characteristic curve ranged from 0.611 to 0.741 for SOS measurements and from 0.745 to 0.797 for BMD measurements. Conclusions.The Omnisense multisite QUS device exhibits reproducible performance. Among the QUS variables, the phalangeal SOS provides the best discrimination of fracture patients.

Femoral biologic plate fixation

New techniques of fracture fixation such as indirect reduction, careful soft tissue handling, and elastic fixation are being used in place of older methods of mechanical stabilization. These new techniques led to the concept of biologic plate fixation. We systematically reviewed the literature and provide an overall evaluation of femoral biologic fixation for fracture treatment. We analyzed 19 studies with 687 patients with 697 femoral fractures. Twenty-three percent of the fractures were subtrochanteric, 29% were diaphyseal, and 48% were supracondylar. Twenty-two percent were open fractures. The majority (81%) were comminuted and AO Types B and C. The overall union rate was 98.4%, with a mean time to union ranging from 10.7 to 24 weeks. Primary or secondary bone-grafting procedures were reported in all but one study with a frequency ranging from 0-55%. The most frequently recorded complications were malunion (0-29%) and reoperation (0-23%). The high union rate, low infection rate (2%), and occasional need for bone graft indicate biologic plate fixation is a viable alternative to modern nailing techniques, particularly in patients with polytrauma.Level of Evidence: Therapeutic study, Level III. See the Guidelines for Authors for a complete description of levels of evidence.

Fluoroscopically assisted surgical treatments of spinal disorders: conceptus radiation doses and risks.

Study Design. A series of anterior-posterior and lateral fluoroscopic exposures at 5 spinal levels were performed on anthropomorphic phantoms simulating the 3 trimesters of gestation. Objectives. To provide normalized data for the determination of conceptus dose specific to gestational stage and treated spinal level. To estimate the conceptus radiation dose and risk associated with typical fluoroscopically guided spinal treatments performed on the pregnant patient. Summary of Background Data. To our knowledge, there are no available data on conceptus doses and radiogenic risks resulting from fluoroscopically guided spinal surgery of the expectant mother. Methods. Direct measurement of conceptus doses from simulated fluoroscopic projections involved in orthopedic surgery at different spinal levels for the 3 trimesters of gestation with use of anthropomorphic phantoms and thermoluminescent dosimetry. Estimation of conceptus radiation risks from a typical pedicle screw fixation and kyphoplasty procedure using the experimentally derived data. Results. Conceptus doses from fluoroscopically guided spinal treatments are smaller than 4 mGy during all gestational stages, provided that the conceptus lies outside the primarily irradiated region. The associated risks of fatal cancer during childhood and congenital malformation on its progeny are at least 2 and 1500 times, respectively, lower than the spontaneous incidence rates. When the embryo is primarily irradiated, mean conceptus dose can be as high as 105 mGy from a nonoptimized exposure. At least 35 minutes of fluoroscopy are required for the induction of deterministic effects. Conclusions. Individual dose assessment is paramount in every pregnancy. Variations in fluoroscopy practices and gestational stage significantly affect fetal doses.

Discriminatory ability of magnetic resonance T2* measurements in a sample of postmenopausal women with low-energy fractures: a comparison with phalangeal speed of sound and dual x-ray absorptiometry.

Rationale and Objectives:We sought to assess the ability of magnetic resonance T2* measurements to discriminate between patients with and without osteoporotic fracture and compare the results with the discriminatory ability of speed of sound (SOS) measured at the phalanx and axial bone mineral density (BMD). Materials and Methods:T2* measurements of lumbar spine were obtained at 1.5 T in 26 postmenopausal women with osteoporotic fractures and 28 age-matched healthy control subjects. A multiecho gradient echo (MEGRE) pulse train sequence was used with echo times of 2.70–74.93 milliseconds using 2.33-millisecond interecho intervals. BMD measurements were made in the axial skeleton. SOS also was measured at the finger phalanges. Results:The in vivo short-term reproducibility for T2* was 1.85%. T2*, spinal BMD, total hip BMD, and SOS measurements were found to give comparable discrimination between normal and osteoporotic women with odds ratios of 2.6, 2.6, 3.2, and 2.2, respectively. Conclusions:T2* measurements of lumbar spine are reproducible and capable of differentiating between postmenopausal women with and those without osteoporotic fractures.

Occupational gonadal and embryo/fetal doses from fluoroscopically assisted surgical treatments of spinal disorders.

Study Design. Simulation of lumbar spine fluoroscopy used during surgical treatments of spinal disorders on a humanoid phantom and monitoring of the scattered radiation levels. Objectives. To assess the potential of adverse effects to progeny due to the preconceptual and embryo/fetal exposure to ionizing radiation resulting from the parental occupational exposure to scattered radiation from lumbar fluoroscopy. Summary of Background Data. There are no available data on embryo/fetal doses resulting from maternal occupational exposure in the orthopedic theater. Besides, studies on staff gonadal doses from fluoroscopically assisted spine surgery are scarce and their results are not generally applicable. Methods. Lumbar spine anterior-posterior and lateral fluoroscopy were performed on an anthropomorphic phantom. Scattered radiation within the orthopedic theater was recorded at the staff genitals and waist level. Gonadal, abdominal surface, and embryo/fetal doses normalized to the dose-area-product specific to each projection were calculated. Results. If the annual dose limits of occupational exposure are continuously exhausted for 10 years, the resulting radiogenic risk of congenital malformation in infants born to the orthopedic theater staff will be at least two orders of magnitude lower than the corresponding spontaneous probability. The occupational exposure of the pregnant mother bears a negligible contribution to the risk of hereditary effect on the newborn’s progeny compared with the natural incidence rate. Conclusions. Radiogenic genetic and embryo/fetal risks resulting from occupational exposure due to fluoroscopically assisted surgical treatments of spinal disorders are well within tolerance levels provided that rigorous confinement to all pertinent occupational dose constraints is established.

Image-guided reconstruction of femoral fractures : Is the staff progeny safe?

The potential of adverse effects to progeny caused by preconceptual and fetal exposure to ionizing radiation is an issue of increasing concern to orthopaedic surgeons and assisting staff. Are these fears justified? How effectively is the embryo or fetus protected, and should pregnant staff alter their duties? In this study, an anthropomorphic phantom was exposed fluoroscopically at two geometries common in surgical reconstruction of proximal femur fractures. Scatter radiation was converted to gonadal dose and embryo or fetal dose with and without use of a protective apron. The genetic risk for the orthopaedic surgeon after 10 years of occupational exposure was estimated to be 16,000 times lower than the natural frequency of heritable disease. The excess risk of childhood cancer associated with the dose accumulated during gestation was at least 600 times lower than the corresponding natural frequency. A properly shielded pregnant orthopaedic surgeon is allowed to do 14 hours of hip fluoroscopy during gestation, whereas 2100 hours of fluoroscopy are required for the induction of gross malformation or mental retardation to the growing embryo or fetus. The supplementary dose constraints for pregnant staff provide adequate protection to the unborn child without affecting regular personnel duties.