Challenges in Occupational Dosimetry for Interventional Radiologists.

This review presents the challenges met by interventional radiologists in occupational dosimetry. The issues mentioned are derived from the recommendations of the International Commission on Radiological Protection, the CIRSE guidelines on "Occupational radiation protection in interventional radiology" and the requirements of the European directive on Basic Safety Standards. The criteria for a proper use of personal dosimeters and the need to introduce optimization actions in some cases are set out in this review. The pros and cons of the electronic real-time dosimeters are outlined and the potential pitfalls associated with the use of personal dosimeters summarized. The electronic dosimeters, together with the appropriate software, allow an active optimization of the interventional procedures.

Optical skyrmion lattice in evanescent electromagnetic fields.

Topological defects play a key role in a variety of physical systems, ranging from high-energy to solid-state physics. A skyrmion is a type of topological defect that has shown promise for applications in the fields of magnetic storage and spintronics. We show that optical skyrmion lattices can be generated using evanescent electromagnetic fields and demonstrate this using surface plasmon polaritons, imaged by phase-resolved near-field optical microscopy. We show how the optical skyrmion lattice exhibits robustness to imperfections while the topological domain walls in the lattice can be continuously tuned, changing the spatial structure of the skyrmions from bubble type to Néel type. Extending the generation of skyrmions to photonic systems provides various possibilities for applications in optical information processing, transfer, and storage.

A set of patient and staff dose data for validation of Monte Carlo calculations in interventional cardiology.

The purpose of this paper is to report a set of experimental values of patient and staff doses in a cardiac catheterisation laboratory using the range of radiographic and geometric parameters from routine clinical practice. The data obtained will be available for validation of Monte Carlo calculations and for training purposes. They will also help optimise radiation protection for patients and staff. Experimental measurements were made with an anthropomorphic phantom, and a monoplane flat detector-based X-ray system was used for interventional cardiology procedures. Standard operational protocols used in clinical practice were applied. Around 1000 patient dose and 5000 staff dose values were measured for different operational conditions (angulations, distances, collimation and wedge filter, magnification, phantom thicknesses, using Copper absorber, etc.). Uncertainties were also estimated. Increase factors of 3-10 for patients and staff doses were measured for the different C-arm angulations.

Sub-100 nm focusing of short wavelength plasmons in homogeneous 2D space.

We present a direct measurement of short-wavelength plasmons focused into a sub-100 nm spot in homogeneous (translation invariant) 2D space. The short-wavelength (SW) surface plasmon polaritons (SPP) are achieved in metal-insulator-insulator (MII) platform consisting of silver, silicon nitride, and air. This platform is homogeneous in two spatial directions and supports SPP at wavelength more than two times shorter than that in free space yet interacts with the outer world through the evanescent tail in air. We use an apertureless (scattering) near-field scanning optical microscope (NSOM) to map directly the amplitude and phase of these SW-SPP and show they can be focused to under 70 nm without structurally assisted confinement such as nanoantennas or nanofocusing. This, along with the use of visible light at 532 nm which is suitable for optical microscopy, can open new directions in direct biological and medical imaging at the sub-100 nm resolution regime.

Controlling the phase and amplitude of plasmon sources at a subwavelength scale.

We present a new class of nanoscale plasmonic sources based on subwavelength dielectric cavities embedded in a metal slab. Exploiting the strong dispersion near the Fabry-Perot resonance in such a resonator, we control the phase and the amplitude of the generated plasmons at the subwavelength scale. As an example, we present a subwavelength unidirectional plasmonic antenna utilizing interference between two plasmonic cavity sources with matched phase and amplitude.

Unintentional exposure of neonates to conventional radiography in the Neonatal Intensive Care Units.

OBJECTIVE: To evaluate the extent of unintentional exposure to X-rays performed during routine diagnostic procedures in the Neonatal Intensive Care Units (NICUs). STUDY DESIGN: During a 1-month period, 157 consecutive neonates from five level-III NICUs were recruited for this study. The mean birth weight was 1747+/-911 g (range: 564-4080 g), and gestational age was 31.6+/-3.6 weeks (range: 24-41 weeks). A total of 500 radiographs were performed including chest (68%), abdomen (17%) and combined chest and abdomen (15%). The average number of radiographs taken per infant was 4.2+/-3.6 (range: 1-21). Unintentional inclusion of body regions other than those ordered was determined by comparing the areas that should be included in the radiation field according to International recommendations, to those that appeared in the actual radiograph. RESULT: A comparison of the recommended borders to the actual boundaries of the radiographs taken show an additional exposure to radiation in all three procedures: 85% of chest radiographs also included the whole abdomen, 64% of abdomen radiographs included both thigh and upper chest and 62% of chest and abdomen radiograph included the thigh. (The range in all procedures was from ankle to upper head.) Between 2 and 20% of the relevant targeted body tissues were not included in the exposed fields resulting in missing data. The gonads of both sexes were exposed in 7% in all chest X-rays. Among male infants, the testes were exposed in 31% of plain abdomen radiographs and 34% of chest and abdomen radiographs. CONCLUSION: In the NICUs participating in the study, neonates are currently being exposed to X-ray radiation in nonrelevant body regions. Higher awareness and training of the medical teams and radiographers are required to minimize unnecessary exposure of newborns to ionizing radiation.

Transcatheter arterial embolisation in anticoagulant-related haematoma--a current therapeutic option: a report of four patients and review of the literature.

The aim of this study is to present the computed tomography (CT) and angiographic findings of life-threatening extraperitoneal haemorrhage complicating anticoagulant therapy, treated with transcatheter arterial embolisation (TAE). CT and angiographic studies of four consecutive patients with large, extraperitoneal anticoagulant-related haematomas (ACH) treated by TAE were retrospectively reviewed. Attention was directed to the location of the haematoma and to the possible presence of active arterial extravasation on CT. Four women (mean age 70 years) with large extraperitoneal ACH's demonstrated on CT as extended rectus sheath haematoma in three and expanding iliopsoas haematoma in one, were successfully treated by TAE of the inferior epigastric (n=3) and lumbar artery (n=1). Two patients were diagnosed by contrast-enhanced CT as having active arterial bleeding within the haematoma requiring TAE. The other two were referred to angiography because of haemodynamic instability. We also reviewed the imaging findings of 26 patients with extraperitoneal ACH's requiring TAE described in the literature. In the reviewed cases, a female predominance was found, the retroperitoneum was the most frequent site and most patients recovered. To conclude, unenhanced CT has proved an excellent modality for the diagnosis of ACH's. TAE has been shown to be an effective and safe method for managing such haematomas when conservative treatment is insufficient. We suggest that whenever a large extraperitoneal ACH is seen on unenhanced CT, a subsequent contrast-enhanced dynamic scan should be performed, unless contraindicated. Enhanced CT has a supplementary role in detecting active bleeding that provides an indication for angiographic therapy. Awareness of this optional treatment improve patient's outcome.

Use of a collagen-based device for closure of low brachial artery punctures.

PURPOSE: To report our experience with the Angioseal vascular closure device for hemostasis of distal brachial artery puncture. METHODS: Between September 2003 and August 2005, 64 Angioseal vascular closure devices were inserted in 64 patients (40 men, 24 women; mean age 65 years) immediately after diagnostic or therapeutic arterial angiographies performed through a 5 Fr to 7 Fr sheath via the distal brachial artery. Ultrasound examination of the brachial artery preceded the angiography in all cases and only arteries wider than 4 mm were closed by the Angioseal. In cases of a sonographically evident thin subcutaneous space of the cubital fossa, tissue tumescence, using 1% Lidocaine, was performed prior to the arterial closure. RESULTS: The deployment success rate was 100%. No major complications were encountered; only 2 patients developed puncture site hematoma, and these were followed conservatively. CONCLUSIONS: Closure of low brachial artery punctures with the Angioseal is simple and safe. No additional manual compression is required. We recommend its use after brachial artery access interventions, through appropriately wide arteries, to improve early patient ambulation and potentially reduce possible puncture site complications.

Incoherent white-light solitons in nonlinear periodic lattices.

We predict the existence of lattice solitons made of incoherent white light: lattice solitons made of light originating from an ordinary incandescent light bulb. We find that the intensity structure and spatial power spectra associated with different temporal frequency constituents of incoherent white-light lattice solitons (IWLLSs) arrange themselves in a characteristic fashion, with the intensity structure more localized at higher frequencies, and the spatial power spectrum more localized at lower frequencies; the spatial correlation distance is larger at lower frequency constituents of IWLLSs. This characteristic shape of incoherent white-light lattice solitons reflects the fact that diffraction is stronger for lower temporal frequency constituents, while higher frequencies experience stronger effective nonlinearity and deeper lattice structure.

Percutaneous balloon dilatation for the treatment of early and late ureteral strictures after renal transplantation: long-term follow-up.

We report our experience with percutaneous balloon dilatation (PBD) for the treatment of ureteral strictures in patients with renal allografts. Of the 422 consecutive patients after renal transplantation in our center 10 patients had ureteral strictures. An additional 11 patients were referred from other centers. The 21 patients included 15 men and 6 women aged 16 to 67 years. Strictures were confirmed by sonography and scintigraphy in all cases. Patients underwent 2 to 4 PBDs at 7-10-day intervals. Clinical success was defined as resolution of the stenosis and hydronephrosis on sequential ultrasound and normalization of creatinine levels. Patients were divided into two groups: those who underwent transplantation more than 3 months previously and those who underwent transplantation less than 3 months previously. PBD was successful in 13 of the 21 patients (62%). There was no statistically significant difference in success rate between the patients with early (n = 12) and those with late (n = 9) obstruction: 58.4% and 66%, respectively. No major complications were documented. PBD is a safe and simple tool for treating ureteral strictures and procedure-related morbidity is low. It can serve as an initial treatment in patients with early or late ureteral strictures after renal transplantation.

Massive hemothorax caused by intercostal artery bleeding: selective embolization may be an alternative to thoracotomy in selected patients.

Massive hemothorax is an indication for thoracotomy. We report a case of an 85-year-old debilitated patient, in whom massive hemorrhage from an actively bleeding intercostal artery was controlled by angiographic embolization. Angiographic embolization proved to be an effective alternative to thoracotomy in this patient, thus avoiding numerous postoperative complications and high mortality. Massive bleeding from an intercostal artery should be considered an indication for angiographic embolization in selected patients.

Free-space optical cross-connect switch by use of electroholography.

An electrically controlled holographic switch is proposed as a building block for a free-space optical interconnection network. The switch is based on the voltage-controlled photorefractive effect in KLTN crystals at the paraelectric phase. It is built of electrically controlled Bragg gratings stored in the volume of the crystal. A compact switch that connects four high-speed fiber-optic communication channels with high efficiency is demonstrated experimentally. The switch performance is investigated and optimized. This switch is extremely attractive for cascaded switching arrays such as those found in multistage interconnect networks.

[Gastrointestinal angiodysplasia as a cause of hemorrhage in the digestive tract and treatment].

Gastrointestinal angiodysplasia is a cause of gastrointestinal bleeding in the elderly, for which surgery has been the only treatment. Estrogen has been reported beneficial in some cases in the past decade. Recurrent bleeding due to angiodysplasia occurred from the small intestine in a 75-year-old woman, and from the right colon in a 91-year-old man. The diagnoses were made by angiography in the first case and colonoscopy and erythrocyte- scanning in the second. There was aortic stenosis in both, a combination which has been reported in other cases. Both patients improved with estrogen therapy. However, after temporary stabilization, gastrointestinal bleeding recurred in the second patient and he was successfully operated on.

Penetration of the holmium:YAG laser through fluid.

PURPOSE: The 2.1-microns pulsed holmium:yttrium-aluminum-garnet (Ho:YAG) laser combines the properties of transmissibility down a flexible silica fiber, enabling percutaneous or endoscopic use, with high water absorption, suggesting good safety characteristics. Laser attenuation in practice, however, is an extremely complex process. The authors studied its effective penetration through blood, bile, urine, saline, and contrast media. MATERIALS AND METHODS: With use of a fiberoptically directed beam and a laser power meter, penetration was measured in vitro with the fiber tip separated from the medium by 5 cm (noncontact mode) and with the fiber tip immersed (contact mode). Logarithm of energy falloff was measured against fluid thickness. Attenuation coefficients (mu) and half value layer (HVL) distances (estimated thickness of fluid needed to have power) were measured. RESULTS: In noncontact mode, power falloff was exponential. Non-sanguinous media had similar values for mu and HVL (mu = 2.24-2.70 mm-1 and HVL = 0.26-0.31 mm) close to theoretical predictions. Blood caused significantly (P < .05) more attenuation (mu = 5.15 mm-1, HVL = 0.13 mm). In contact mode, attenuation was much more complex with "plateau" distances of up to 1.2 mm, below which attenuation was negligible. The HVL distances ranged from 0.9 to 1.8 mm and were up to 14 times higher. The main reason is probably the formation of microcavities around the fiber tip. CONCLUSION: The effective penetration of this laser when immersed may be several times that predicted, with important clinical implications.

Holmium-YAG laser for gall stone fragmentation: an endoscopic tool.

A systematic review of the 2.1 mu holmium-YAG laser for gall stone lithotripsy was undertaken. This infrared laser, which can be used endoscopically and percutaneously, has safety advantages over other lasers and has potential as a general purpose vascular and surgical tool. Twenty nine gall stones (mean mass 1.3 g) were fragmented in vitro using pulse energies of 114 to 159 mJ/pulse at 5 Hz with a 0.6 mm fibre, while being held in an endoscopy basket. All stones were successfully fragmented, requiring an average of 566 pulses with a 5 Hz pulse repetition frequency. The number of pulses required increased with gall stone size and mass (p < 0.01), and decreased with both pulse energy (p < 0.01) and operator experience (p < 0.05). The biochemical content of the stone did not significantly affect the number of pulses needed. The potential hazard of the laser to the biliary endothelium was investigated. At the pulse energies used, five pulses at close contact penetrated into the serosa of fresh gall bladder wall. No damage was seen when two pulses were fired. This laser shows considerable promise in gall stone lithotripsy. Until further safety data are available, however, its use with endoscopic vision is advised.

[Primary and metastatic hepatic cancer: the surgical option].

Major hepatic resection is the treatment of choice in patients with primary and secondary liver cancer. During a 22-month period 31 men and 27 women (mean age 63 years, range 14-84) with space-occupying hepatic lesions were admitted. All 15 patients with benign lesions were operated, except for 3 in whom a liver abscess was drained percutaneously. Of the 43 with malignant liver lesions, 30 had liver metastasis secondary to colorectal cancer, 15 of whom underwent major, anatomical and nonanatomical, liver resection and 1 had cryoablation of the tumor. 9 had hepatocellular carcinoma, 1 of whom had a 4-segment non-anatomical resection and 1 tumor cryoablation. 2 with metastasis from a neuroendocrine tumor had anatomical resection of liver lobes. Of 2 with liver metastasis secondary to breast cancer, 1 underwent resection. CT portography, intraoperative ultrasonography and intraarterial injection of Lipiodol were found to be very useful in selecting patients for liver resection.

Ulnar translation of the scaphoid: an early X-ray sign of rheumatoid arthritis.

The distance between the os trapezium and radius (which we called scaphoid distance) became shorter during the course of rheumatoid arthritis (RA). Measurement of this distance was performed in 600 hands (300 patients), using standard position of patient's hand in supination with permanent angle (15-20%) between the axis of the radius and the axis of the third metacarpal bone (scaphoid distance). This provided a stable distance between the most distal point of the radial styloid process and most proximal point of the os trapezium. The patients were divided into two groups: a control group consisting of 100 patients with no inflammatory joint disease, and a group of 200 patients suffering from RA. Patients suffering from RA with bone erosions had smaller scaphoid distance than those suffering from RA without bone erosions. The ratio between the distance from the distal radius to the most distal point of the third metacarpal bone and scaphoid index was called carpo-metacarpo-scaphoid index. It excluded the constitutional influence on the scaphoid distance. The shorter the scaphoid distance, the bigger the carpo-metacarpo-scaphoid index. The average indexes were: in the control group 7.8 (+/- 0.4), in group 2A with advanced RA 21.1 (+/- 4.1), and in group 2B with early RA without bone changes 12.0 (+/- 1.6). The results were statistically significant. The measurements are easy to perform and may be helpful in the early X-ray diagnosis of RA, when there are no bone erosions, or narrowing of articular spaces.