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PubMed2002

Radiological protection for diagnostic examination of pregnant women.

Application of diagnostic X-ray examination to pregnant women is complicated since risks to both mother and embryo/fetus must be considered. Embryos and fetuses are more sensitive to radiation than adults or children. The threshold doses for fetal death, malformations and mental retardation which are deterministic effects, are reported to be 100-200 mGy or higher. The relative risk for childhood cancer due to radiation at an absorbed dose of 10 mGy during embryonic/fetal development has been estimated at 1.4. However, the absorbed dose of the embryo/fetus during X-ray diagnostic examination in which the X-ray beam does not irradiate the embryo/fetus directly such as maternal skull and chest X-ray is extremely low, less than 0.01 mGy. Thus these diagnostic procedures are not a problem from the perspective of radiological protection of the embryo/fetus. However, for pelvic CT scan and barium enema in which the uterus is directly within the X-ray beam, the absorbed doses to the embryo/fetus are about 20-80 mGy and 10-20 mGy, respectively. Therefore, medical staff must pay careful attention to the embryo/fetus in application of these examinations. Pregnant women who were not aware of pregnancy at the time of their diagnostic exposure have great anxiety about radiation from such X-ray examinations. However, fetal doses below 100 mGy should not be considered a reason for terminating a pregnancy.

Dose-Response Relationship, Radiation↗
PubMed2006

Direct index of refraction measurements at extreme-ultraviolet and soft-x-ray wavelengths.

Coherent radiation from undulator beamlines has been used to directly measure the real and imaginary parts of the index of refraction of several materials at both extreme-ultraviolet and soft-x-ray wavelengths. Using the XOR interferometer, we measure the refractive indices of silicon and ruthenium, essential materials for extreme-ultraviolet lithography. Both materials are tested at wavelength (13.4 nm) and across silicon's L2 (99.8 eV) and L3 (99.2 eV) absorption edges. We further extend this direct phase measurement method into the soft-x-ray region, where measurements of chromium and vanadium are performed around their L3 absorption edges at 574.1 and 512.1 eV, respectively. These are the first direct measurements, to our knowledge, of the real part of the index of refraction made in the soft-x-ray region.

Journal Article↗
PubMed2003

Optical design of a spectrometer-monochromator for the extreme-ultraviolet and soft-x-ray emission of high-order harmonics.

A grazing-incidence spectrometer-monochromator for diagnostics and application of the extreme-ultraviolet (EUV) and soft-x-ray high-order harmonics generated by the interaction between a few-optical-cycle laser pulse and a gas jet has been fabricated. We address the necessity of high-resolution spectral and spatial analyses of the high-order harmonics as well as their use as short EUV backlighters in pump-probe experiments. The spectrometer that we present uses a variable-line-spaced flat grating illuminated in the converging light coming from a toroidal mirror. The spectrum is stigmatic, and the focal surface is almost flat in a wide spectral region. The detector is a microchannel plate intensifier with a phosphor screen optically coupled to a CCD camera; it can be moved by means of a linear drive to acquire different portions of the spectrum in the 5-75-nm region. The resolution is almost limited by the pixel size of the detector. We apply the same optical scheme to achieve a constant-deviation-angle monochromator by substituting an exit slit for the detector block: The rotation of the grating gives the spectral scanning. A monochromator for the 5-50 nm spectral region is achieved.

Journal Article↗
PubMed1980

Summary of the means used to positively identify the American victims in the Canary Islands crash.

On board the Pan American aircraft, 326 were killed as a result of the collision with the KLM aircraft at Santa Cruz de Tenerife airport in the Canary Islands on 27 March, 1977. Of the remains returned to the United States, 212 were identified as Americans from the Pan Am, four from the KLm aircraft. Dental comparison provided the principal means of identification, especially ante- and post-mortem radiographs. Medical X-rays were extremely useful and provided the next most frequently used means of identification. Fingerprints, medical finding, and personal effects were also used, but less extensively than might be expected. The severe charring and the inability to prove conclusively to whom many of the personal effects belonged accounted for these differences. The use of medical X-rays for identification was possible in large part because many of the passengers were older and had numerous antemortem X-rays available for comparison.

Accidents, Aviation↗
PubMed1995

[Possibilities for using sonography as a diagnostic procedure in fractures during the growth period].

Alzen et al. found that of 2,006 X-rays taken to identify fractures in childhood, only 345 fractures could be verified. To minimize this discrepancy, the traumatology department at the RWTH in Aachen prefers performing ultrasound before taking an X-ray. We call this procedure "osteosonography". If one uses osteosonography, fractures can be recognized, interpreted and, in some cases, immediately treated without taking additional X-rays. Furthermore, it is then possible not to have to X-ray the extremities, resulting in a reduction in the amount of radiation to the gonads and epiphyses. Other advantages of osteosonography are that it is then possible to compare examinations of the contralateral side, interpret bone and tissue at the same time, and do the examination in the presence of the parents. After 180 children had been examined, it became apparent that in 53.3% of all children, the X-ray could be replaced by osteosonography. On the one hand, we had children with no ultrasonographic suggestion of fractures and, on the other, we had fractures with no indications for repositioning or operating (e.g. "bulge fractures"); these could be treated at once with cast. We are of the opinion that our experience with osteosonography justifies generally making this the first diagnostic measure before X-raying children during the growth phase. A this way, radiation can be minimized, resulting in a reduction in X-ray-induced damage.

Adolescent↗
PubMed1986

[Cerebral cysticercosis--report of an operated case].

A rare case of cerebral cysticercosis is reported. The patient, a 49-year-old man, had been to Central America several times since 1963. He had an episode of seizure in March 1980 and again in August 1983, and was admitted to our hospital. Skull X-ray, cerebral angiography, scintigraphy, EEG, CSF examination, Chest X-ray, blood and urine examinations were all normal. CT scan only revealed a small lesion in the left frontal lobe as a well circumscribed round low density area with ring-like enhancement. An operation was performed for a suspected brain tumor. However, a cyst was found in the left frontal lobe and was totally extirpated. The microscopic examination revealed a scolex, hooks, and a cyst characteristic of cysticercosis. Postoperative examinations, X-ray of extremities, abdominal CT and immunological reactions of cysticercosis showed no abnormal findings. Cerebral cysticercosis, a rare disease in Japan, may increase proportionally with the increase of world travel. In this case, CT scan was useful for the diagnosis of cysticercosis.

Brain Diseases↗
PubMed2005

A giant gamma-ray flare from the magnetar SGR 1806-20.

Two classes of rotating neutron stars-soft gamma-ray repeaters (SGRs) and anomalous X-ray pulsars-are magnetars, whose X-ray emission is powered by a very strong magnetic field (B approximately 10(15) G). SGRs occasionally become 'active', producing many short X-ray bursts. Extremely rarely, an SGR emits a giant flare with a total energy about a thousand times higher than in a typical burst. Here we report that SGR 1806-20 emitted a giant flare on 27 December 2004. The total (isotropic) flare energy is 2 x 10(46) erg, which is about a hundred times higher than the other two previously observed giant flares. The energy release probably occurred during a catastrophic reconfiguration of the neutron star's magnetic field. If the event had occurred at a larger distance, but within 40 megaparsecs, it would have resembled a short, hard gamma-ray burst, suggesting that flares from extragalactic SGRs may form a subclass of such bursts.

Journal Article↗
PubMed2002

Preliminary study on extremely small angle x-ray scatter imaging with synchrotron radiation.

Among the medical physics community, there is nowadays a great interest in the possible implementation of scatter imaging techniques, especially in the field of breast imaging. It is well known that malignant lesions and normal tissue differ in their scattering signatures, and thus scattered radiation can provide a powerful tool to distinguish between the two cases. Up to now, most of the proposed techniques rely on the detection of radiation scattered at angles of the order of a few degrees, which in most cases results in very high contrast values. On the other hand, at those relatively large angles the scattered flux is relatively low with respect to the primary, which often implies the necessity of increasing the dose delivered to the sample in order to achieve sufficient statistics. Furthermore, most of these techniques are based on pencil beam set-ups, which results in an increase of the overall duration of the examination. We propose here an alternative approach based on the detection of radiation scattered at extremely small angles, of the order of approximately 100-200 microrad. This results in a relatively high scattered flux (5-10% of the primary) and in the possibility of utilizing a fan beam geometry, which reduces the acquisition times with respect to pencil beam set-ups. Images of several samples have been acquired, demonstrating that the proposed technique results in an increased contrast with respect to absorption imaging. Possible in vivo implementations of the technique at no dose expense are finally discussed.

Algorithms↗
PubMed1983

[Phlebography of the upper extremity: assessment of various x-ray signs].

The article reports on the findings obtained in 56 serial phlebographies of the upper extremity. Using 17 phlebographies without pathological findings as basis, the physiological phenomena of venous contrasting in the region of the shoulder and arm are examined. The remaining phlebograms with pathological findings are assessed according to different criteria, such as localisation and extent of venous vascular occlusion, visualisation of vascular clot and formation of collaterals resulting in collateral circulation.

Arm↗
PubMed1979

[The part taken by X-ray investigation for closed soft tissue injuries on the extremities (author's transl)].

Special X-ray pictures taken of soft tissues for the treatment of closed soft tissue injuries on the extremities, give valuable diagnostic advises. Rupture on the surface of muscles, the lesion to the tendon Achilles and the lig. patellae proprium, tumours, muscle waisting following plexus or periferial nerve lesions etc. by X-ray investigation can be exactly delineated and the site, extension and type of damage defined.

Adult↗
PubMed2005

Replacement of a severe chronic post-traumatic aneurysm of the ascending aorta with aortic valve conduit--reconstruction of the anterior mitral valve ring and implantation of A-V sequential/biventricular pacemaker.

We present the case of a 23-year-old African professional footballer who was admitted on April 1, 1999 to the Cardiology Department of the University Hospital in Magdeburg, on an emergency basis, from a regional lung clinic. According to the history, he was involved in a collision with an opposing player during a football match in his country (in Africa). He lost consciousness for a short time, but continued playing to the end of the match. About two months later he was invited by a German football club for a check-up, with the view to ultimately playing for the club. The team did not find him physically fit enough to play professional football, so he decided to go to Paris by bus on March 31, 1999. During the journey he suddenly became cardio-pulmonary decompensated and had to undergo cardio-pulmonary resuscitation (CPR). He was intubated and placed on a respirator and immediately transferred to a nearby lung clinic. From the lung clinic he was transferred to the Intensive Care Unit of the Cardiology Department of the Magdeburg University Hospital, on April 1, 1999 as an emergency case. He was intensively treated with catecholamines, intravenous ACE inhibitors and diuretics. His clinical condition did not improve appreciably. His chest X-ray showed extreme dilatation of the right and left heart as well as extreme pulmonary congestion.

Adult↗
PubMed1998

Toxic cardiogenic shock in a patient receiving weekly 24-h infusion of high-dose 5-fluorouracil and leucovorin.

A 54-year-old man was treated with weekly 24-h infusion of high-dose 5-fluorouracil (2600 mg/m2) and leucovorin (100 mg/m2) for metastatic colon cancer. At first, he tolerated the treatment well and no significant toxicity was identified. After a total of eight courses of treatment, a stable disease was observed, but mild shortness of breath was found on occasion. The patient had no previous history of cardiac disease and the heart performance assessed by left ventricular ejection fraction before treatment was normal. Unfortunately, acute pulmonary edema with lethal cardiogenic shock occurred during the ninth course of treatment, in spite of intensive medical treatment. The chest X-ray showed extreme cardiomegaly. Repeated assessment of his heart function by echocardiogram and ventricular ejection fraction revealed a very poor cardiac performance. Toxic cardiogenic shock during weekly 24-h infusion of high-dose 5-fluorouracil and leucovorin is extremely rare. To the best of our knowledge, no case has been reported in the English literature. We report a case and the relevant literature about the incidence, clinical picture and possible pathophysiology on 5-fluorouracil-related cardioxicity is reviewed.

Acute Disease↗
PubMed2003

Modified Fresnel zone plates that produce sharp Gaussian focal spots.

A modified Fresnel zone plate that can produce an approximate Gaussian focal spot is proposed for the focusing and imaging of soft x rays and extreme ultraviolet radiation. The selection conditions for the positions and the widths of the concentric open rings are analytically presented. The focal spot size can be much smaller than the width of the narrowest open ring, and the sidelobes and the higher orders can be effectively suppressed. Through numerical experiments, we confirm that a Gaussian focal spot with a beam width of 7.7 nm can be produced by a modified Fresnel zone plate with a minimum structure size of 30 nm.

Journal Article↗
PubMed2001

[Computer-assisted, robot-assisted hip prosthesis--standard procedure or specialty indication?].

Approximately 150,000 total hip replacements annually are performed in Germany, with an increasing incidence of implants carried out on young subjects. Due to aseptic loosening, this group will undergo some revision arthroplasty after 15 years. Therefore, a permanent fixation appears mandatory. In case of posttraumatic or postoperative anatomical changes, exact preoperative planning by x-rays is extremely difficult. This might result in a higher rate of complications (e.g., displacement of the implanted prosthesis, fractures of the proximal femur), as documented by the available literature. The preoperative planning with CT images obtained at the 3D workstation shows the exact cortical situation, while the robot-assisted surgery allows the precise execution of the preoperative plan during surgery. By this point of time, long-term results of computer-guided, robot-assisted implantation of endoprosthesic devices are still lacking. However, the preliminary data indicate good results by means of anatomical position of the endoprosthesis and perioperative complications.

Arthroplasty, Replacement, Hip↗
PubMed2001

[Value of a new non-contact biometer for intraocular crystalline lens power calculation].

PURPOSE: One of cataract surgery's current imperatives involves refraction: the power of the lens implant must be calculated as accurately as possible. Here we present a new method of biometric ocular measurement using the partial optical consistency interferometer. MATERIAL AND METHODS: This investigation studied the axial length measurement of 100 eyes. Five measurements were taken with a classic echobiometric contact technique using the ultrasonic mode; 5 others were taken with the infrared noncontact technique (IOL Master, Zeiss Humphrey). The latter technique is based on interferometric biometry with optical consistency and measurements were taken with an infrared luminous ray. With extreme rapidity and no contact, the device provides a complete biometry, including axial length, keratometry, and anterior chamber depth. It includes a built-in computer. RESULTS: Comparing the ultrasonic and infrared measurements emphasizes the precision and particularly the high reproducibility of the infrared method. The standard deviations of the samples were significantly lower for the 100 measurements. Its limitations depends on the type of cataract since success was not obtained for certain posterior subcapsular opacities. DISCUSSION: This new method of performing a biometry with a partial consistency interferometer contributes a number of advantages: speed, its noninvasive nature with no contact, the high reproducibility of the exam, as well as precise measurements as shown by the difference in the standard deviations of the two methods. CONCLUSION: Biometry using the optical consistency interferometer seems to be a reliable, reproducible, and precise technique that brings great precision for the calculation of the power of the intraocular implant in cataract surgery.

Diagnostic Techniques, Ophthalmological↗