Ionising radiation during internal fixation of extracapsular neck of femur 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.

Screening time for extra-capsular proximal femoral fracture fixation; the difference between extra-medullary and intra-medullary implant usage

The aim of this study was to compare the fluoroscopic screening time used for treatment of fractures of the trochanteric region of the femur using two different implant systems. Data were collected from 277 proximal femoral fracture fixations. A dynamic hip screw (DHS) was used in 145, and an intra-medullary hip screw (IMHS) was used in 132. There was no difference between the two groups with respect to age, gender or side. Altogether, there were 42% two parts, 35% were three parts and 23% were four parts extra-capsular neck fractures. There was no statistical difference in ionising radiation exposure in closed reduction of these fractures regardless of the fracture configuration or surgical experience of the surgeon. The mean screening time to implant a DHS in two part fractures was 0.48 min, for three part fractures it was 0.45 min and for four part fractures it was 0.46 min. The mean screening time to implant IMHS was 1.02 min for two part fractures, 0.96 min for three part fractures and 1.03 min for four part fractures. These differences were statistically significant (P < or = 0.05).

Navigierte Osteosynthese des proximalen Femurs

Screw position in femoral head has been considered the most important predictive factor for mechanical failure in pertrochanteric osteosynthesis, and correct positioning is assisted by fluoroscopic control. Although fluoroscopy leads to precise and reproducible results, it is associated with scattered radiation to the patient and surgical staff. Computer-assisted surgery (CAS) may be an alternative in means of achieving precise screw insertion with a low radiation dose. We designed a laboratory study in which artificial proximal femora were submitted to insertions of a dynamic hip screw (DHS) and an anti-rotational screw (ARS). Three set-ups were tested: (1) conventional implantation with two simultaneous C-arms using a guide wire; (2) drilling and implantation controlled by CAS solely with a 3.2-mm drill bit, then insertion of a guide wire and drilling for the dynamic hip screw; (3) after navigated drilling (3.2 mm) a fluoroscopic control was performed. Five variables were used comparing methods and surgeons: operation time, radiation time, tip-apex distance (TAD), and the insertion neck-shaft angles of DHS and ARS. Considering TAD as a precision parameter, CAS led to screw insertion as accurate as with fluoroscopic control, with a reduction of radiation time up to 93%.

Conceptus radiation dose assessment from fluoroscopically assisted surgical treatment of hip fractures

Our aims in the present study were to (a) provide normalized dose data for the estimation of the conceptus dose from fluoroscopically assisted surgical treatment of hip fractures carried out during all trimesters of pregnancy and (b) estimate the conceptus radiation dose and risks associated with fluoroscopy during a typical treatment of hip fracture performed on a pregnant woman. Conceptus doses normalized to entrance surface dose (ESD) or dose area product (DAP) were obtained with the help of anthropomorphic phantoms simulating pregnancy in the three trimesters of gestation. ESD and conceptus dose measurements were carried out using thermoluminescent dosimeters. DAP to conceptus dose conversion factors were estimated for the first, second and third trimesters of gestation. Conceptus dose data normalized to ESD were also estimated to investigate whether these conversion factors may be used for procedures carried out in x-ray units not equipped with a DAP meter. Fluoroscopically assisted surgical treatments were performed in 18 women. The projections involved in these procedures are (a) posteroanterior (PA) and (b) lateral crosstable 45 degrees (LC). Radiation doses for a potential conceptus were estimated by using normalized dose data obtained in phantoms. The results consist of tabulated dose data normalized to DAP or ESD for the estimation of a conceptus dose. An important finding of this study was that the total DAP of a procedure, instead of the individual DAP values of each projection, could be used for the accurate estimation of the conceptus dose. Conceptus doses calculated using dose data normalized to ESD are about 23% higher compared to those estimated using data normalized to DAP. This discrepancy may be attributed to the contribution of scattering radiation from PA projection to ESD measurement of LC projection and vice versa. Therefore, dose data normalized to ESD do not provide accurate conceptus dose estimation. Doses normalized to DAP showed a dependence on (a) tube potential and (b) tube filtration. Data are provided to extent the doses normalized to DAP for the standard spectrum to other tube voltages and filtrations. The maximum dose for a potential conceptus was 0.425 mGy for a patient irradiated for 50 seconds during the PA projection and for 40 seconds during the LC projection. Although the total duration of fluoroscopy is usually less than 2 minutes during a typical procedure, screening time as long as 14 minutes has been reported in the literature for treatment of complex fractures. The relationship between conceptus dose and fluoroscopy time found in the current study showed that, in these cases, the radiation dose received by a conceptus may exceed 1 mGy. In conclusion, an accurate estimation of conceptus doses associated with fluoroscopically assisted surgical treatment of hip fractures can be made using the DAP normalized dose data provided in this study. Conceptus doses from a typical procedure is less than 1 mGy during all trimesters.

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.

Distal locking of femoral nails under direct vision through a cortical window

We present a salvage technique for distal femoral interlocking under direct vision through a window in the anterior femoral cortex in a subgroup of six patients, among those presented to our institution during the last 10 years with a femoral shaft fracture treated with reamed, locked intramedullary nailing. The common characteristic of these patients was the performance of distal locking under direct vision through a small window in the anterior femoral cortex because of intraoperative dysfunction of the image intensifier. Screw insertion was successful in all cases. All fractures and all cortical windows healed uneventfully. No postoperative fractures occurred through the cortical defect. This technique, despite being a salvage one, has proven a safe alternative to the common distal targeting techniques. It can be used when an image intensifier is unavailable without jeopardizing the excellent clinical and radiographic outcome of reamed locked nailing of femoral shaft fractures.

Radiation exposure to the spine surgeon during fluoroscopically assisted pedicle screw insertion

STUDY DESIGN

In vitro study to determine occupational radiation exposure during lumbar fluoroscopy.

OBJECTIVES

To assess radiation exposure to the spine surgeon during fluoroscopically assisted thoracolumbar pedicle screw placement.

SUMMARY OF BACKGROUND DATA

Occupational radiation exposure during a variety of fluoroscopically assisted musculoskeletal procedures has been previously evaluated. No prior study has assessed fluoroscopy-related radiation exposure to the spine surgeon.

METHODS

Bilateral pedicle screw placement (T11-S1) was performed in six cadavers using lateral fluoroscopic imaging. Radiation dose rates to the surgeon's neck, torso, and dominant hand were measured with dosimeter badges and thermolucent dosimeter (TLD) rings. Radiation levels were also quantified at various distances from the dorsal lumbar surface using an ion chamber radiation survey meter.

RESULTS

The mean dose rate to the neck was 8.3 mrem/min. The dose rate to the torso was greatest when the surgeon was positioned ipsilateral to the beam source (53.3 mrem/min, compared with 2.2 mrem/min on the contralateral side). The average hand dose rate was 58.2 mrem/min. A significant increase in hand dose rate was associated with placement of screws ipsilateral to the beam source (P = 0.0005) and larger specimens (P = 0.0007). Radiation levels significantly decreased as distance from the beam source and dorsal body surface increased. The greatest levels of radiation were noted on the side where the primary radiograph beam entered the cadaver.

CONCLUSION

Fluoroscopically assisted thoracolumbar pedicle screw placement exposes the spine surgeon to significantly greater radiation levels than other, nonspinal musculoskeletal procedures that involve the use of a fluoroscope. In fact, dose rates are up to 10-12 times greater. Spine surgeons performing fluoroscopically assisted thoracolumbar procedures should monitor their annual radiation exposure. Measures to reduce radiation exposure and surgeon awareness of high-exposure body and hand positions are certainly called for.