[Radiation protection clothing in X-ray diagnostics - comparison of attenuation equivalents in narrow beam and inverse broad-beam geometry]. / Strahlenschutzkleidung in der Röntgendiagnostik - Vergleich der Schwächungsgleichwerte im schmalen Strahlenbündel und in inverser Breitstrahlgeometrie.

PURPOSE: Standard DIN EN 61 331-1 for attenuation measurements in the narrow and broad beam as well as DIN 6857-1 for the determination of shielding properties in the inverse broad-beam geometry are available for testing the attenuation of protection clothing. The attenuation measurements in the narrow beam don't consider scattered radiation and fluorescence due to the arrangement. This leads to the fact that the protective effect of lead-free materials will be misestimated when compared to lead. Therefore, the differences in attenuation equivalents, determined by both test methods for topical radiation protection aprons, were examined. MATERIALS AND METHODS: The attenuations in inverse broad-beam geometry according to DIN 6857-1 and in the narrow beam according to DIN EN 61 331-1 were measured using commercially available aprons. They were made of lead, lead-reduced and lead-free materials. For determination of the attenuation equivalents, certificated lead-foils with high purity and a precise thickness of 0.1 to 1.25 mm were used. RESULTS: The measurements in the narrow beam according to DIN EN 61 331-1 showed that nearly all aprons reach the required lead equivalent at mid-range tube voltages of 100 kV. At higher and lower tube voltages, the requirements of DIN EN 61 331-3 were largely not met. In contrast, the testing of the same aprons in inverse broad-beam geometry according to DIN 6857-1 showed that only a few aprons meet the requirements for being classified in the nominal protection class. CONCLUSION: The measurements suggest that testing method DIN 6857-1 has yet to prevail and that manufacturers are just beginning to develop the appropriate protective materials.

[Simulation of the heart action: a computer controlled module for the generation of variable flow patterns]. / Herzaktions-Simulation: Ein computergesteuertes Modul zur Erzeugung variabler Strömungsprofile.

AIM: The development of a computer controlled pump for the generation of variable flow patterns with high reproducibility for simulating the haemodynamics in physiological model circuits. MATERIAL AND METHODS: The module is controlled by an arbitrary function generator. The shape of the flow profile is generated on the PC based on mathematical functions or drawn by hand. The amplified signal drives a DC motor which is coupled magnetically to a geared pumphead. The lack of mechanical coupling ensures smooth running and a complete attenuation of motor vibrations as well as a disturbance-free flow profile. The spectra were analyzed by Doppler-sonography with a 5 - 12 MHz linear probe and with pressure sensors. Silicon tubes were used as simulated vessels and a water-glycerine mixture with particles of cellulose as simulated blood. RESULTS: The generated flow patterns (constant flow and multi-phase patterns) correlate highly with the measured pressure- and velocity profiles. CONCLUSION: The variability and high reproducibility of the flow profiles and the realtime control of the signal parameters make the simulation of dynamic processes and haemodynamic long-time studies feasible. The module developed facilitates detailed studies of high reproducibility with physiological and pathological flow models and with simulated blood.

Quality control of mitigation methods for unusually high indoor radon concentrations.

The present study's objective was to control the quality of different mitigation methods for unusually high indoor radon (222Rn) concentrations of up to 274,000 Bq m(-3) in a village (Umhausen, 2,600 inhabitants) in western Tyrol, Austria. Five years after mitigation, five different remedial actions were examined on their quality by means of measuring indoor radon concentrations with charcoal liquid scintillation radon detectors and with a continuously recording AlphaGuard detector. Mitigation method in house 1--a mechanical intake and outlet ventilation system with heat exchanger in the basement, combined with a soil depressurization system--was characterized by long-term stability. With most favorable air pressure (+100 Pa) in the basement, mean basement radon concentrations in the winter were reduced from 200,000 Bq m(-3) to 3,000 Bq m(-3) by this method 5 y after mitigation. Acting against experts' instructions, the inhabitants had switched off the ventilation system most of the time to minimize power consumption although it had been proven that ventilation reduced mean basement radon concentration by a factor of about 3 in the winter and about 15 in the summer. Mitigation method in house 2-soil depressurization with two fans and loops of drainage tubes to withdraw radon from the region below the floor and outside the basement walls, and from soil below that part of the house with no basement-had been the most successful remedial measure until the winter of 1999 (i.e., 6 y after mitigation), when micro-cracks opened and consequently mean basement radon concentration increased from 250 Bq m(-3) to 1,500 Bq m(-3). Measures to block these microcracks and to minimize soil drying are being developed. Five years after mitigation, the remedial method used in house 3--a multilayer floor construction, where a fan was used to suck radon from a layer between bottom slab and floor-reduced winter mean radon concentration from 25,000 Bq m(-3) to 1,200 Bq m(-3), with the ventilation on and the basement door open. Mitigation method in house 4--a basement sealing technique--was unsuccessful with almost identical radon concentrations during all the five years since mitigation had started. Mitigation method in house 5--a waterproof basement technique especially for future homes--reduced mean basement radon concentration below 300 Bq m(-3) and mean ground floor radon concentration below 200 Bq m(-3), which is the Austrian action level for newly constructed buildings. These findings indicate that even in areas with extremely high radon concentrations, effective mitigation of indoor radon can be achieved provided that house-specific long-term, stable mitigation techniques are applied.

Improvement of prostate cancer screening by determination of the ratio free/total PSA in addition to PSA levels.

BACKGROUND: The measurement of prostate specific antigen (PSA) is widely used in screening programs for early detection of prostate cancer. However the specificity for cancer detection is limited because serum PSA is also elevated in patients with benign prostatic-hyperplasia (BPH) and/or prostatitis. It has been shown recently, that the ratio of free/total PSA in serum is lower in malignant prostatic disorders than in non-malignant ones and therefore might be a parameter to improve screening specificity. In a retrospective study, we tested whether free/total PSA helps to distinguish between BPH and prostatic carcinoma in men with elevated serum PSA. METHODS: A total of 266 men have been identified with age-specific elevated serum PSA levels using a conventional PSA determination kit. Subsequently their disease was proven by biopsies. Free and total PSA levels in these serum samples were measured using the DELFIA PSA dual label free/total PSA kit. RESULTS: The mean free/total PSA of 64 patients with prostate cancer was 0.10 and was significantly (P = 0.001) different from the mean free/total PSA of 202 men who were histologically free of cancer, which was 0.17. Receiver-operating-characteristic curve (ROC) analysis showed that using a free/total PSA ratio of 0.18 as a biopsy criterion in men with an elevated PSA serum level, 37% of the negative biopsies could be eliminated while still detecting 94% of all carcinomas. CONCLUSIONS: These results show that the ratio of free/total PSA is a useful determination and can improve specificity of prostate cancer screening.

Frequency and clinical significance of transition zone cancer in prostate cancer screening.

Approximately 20% of prostate cancers originate in the transition zone (TZ). Although transrectal ultrasound (TRUS) and systematic biopsies have improved peripheral zone (PZ) cancer diagnosis, additional biopsies directed into the TZ may further improve cancer detection. To evaluate the frequency and clinical significance of TZ cancers, we added two TZ biopsies to the routinely performed sextant biopsies. Three hundred forty patients (aged 45-75) from our prostate-specific antigen (PSA) screening study (21,078 volunteers) with negative rectal examination findings underwent systematic and TZ biopsies with three-dimensional ultrasound equipment. All patients had elevated PSA levels according to age-specific reference ranges. Ninety-eight of 340 men (28.5%) had biopsies positive for cancer. Of these 98 cancers, 28 (28%) originated in the TZ only and 5 (5%) were located in the TZ as well as the PZ. Eight men showed TZ abnormalities on ultrasound images, of whom four had biopsies positive for TZ cancer. The TZ cancers detected were pathologically significant in 96% (27 of 28). Seventy-one percent (20 of 28) of pathologically staged cancers were found to be organ confined and all combined TZ and PZ cancers were advanced tumors. We conclude that TZ biopsies enhance the cancer detection rate in prostate cancer screening and should therefore be added to the routinely done sextant biopsies in men with PSA elevation and normal digital rectal examination findings.

Posttraumatic posterior urethral stricture repair: anatomy, surgical approach and long-term results.

PURPOSE: We describe the anatomy, surgical approach and long-term results of posterior urethral stricture repair. MATERIALS AND METHODS: Between 1975 and 1991, 86 patients underwent surgery for posttraumatic posterior urethral stricture. In 65 patients the urethral lesion was corrected by 1-stage reconstructive surgery via the perineal approach. In 21 patients the urethra was reconstructed with a 2-stage procedure. In an anatomical study the course of the urethra through the pelvic floor was investigated and the concomitant structures were dissected. According to the anatomy a perineal approach was used in 7 male adult cadavers. RESULTS: Due to the optimized anastomotic technique urinary flow rates of more than 20 ml. per second could be achieved in 29 of all 42 patients followed. Only 6 of these patients had peak urinary flow rates of less than 15 ml. per second. No patient had any recurrent strictures at the anastomotic site that would have required surgical revision. CONCLUSIONS: Our results suggest that adequate primary care and the perineal approach combined with an exact anastomosis technique are essential for successful treatment of posttraumatic strictures of the posterior urethra.

Usefulness of the ratio free/total prostate-specific antigen in addition to total PSA levels in prostate cancer screening.

OBJECTIVES: Two different studies were performed. The aim of the first study was to define whether the measurement of the ratio between free and total prostate-specific antigen (f/t PSA) in serum may enhance the ability of PSA-based screening for early detection of prostate cancer in men with elevated serum PSA levels. A second study was undertaken to investigate the value of f/t PSA ratio in serum to improve the specificity of prostate cancer screening in men with serum PSA levels between 2.5 and 10.0 ng/mL. METHODS: In a retrospective study of 266 men with elevated PSA levels and proven biopsy results, f/t PSA levels were measured using deep frozen serum samples. In a second study we enrolled 158 men with elevated PSA levels according to age reference ranges apparent from our current PSA screening study with additional measurement of the f/t PSA ratio. All study volunteers with a free f/t PSA ratio cutoff point of < or = 22% underwent digital rectal examination, transrectal ultrasonography, and biopsy of the prostate. Free and total PSA levels were measured with the Delfia PSA dual label f/t PSA kit (Wallac Oy Turku, Finland). RESULTS: 106 of 158 men with elevated total PSA values between 2.5 and 10.0 ng/mL (group 1) have been further evaluated and 37 prostate cancers were detected. Mean percentage of free PSA was 10% in men with cancer and 22% in men with benign prostatic hyperplasia. Using a f/t PSA ratio of < or = 22% as a biopsy criterion 30% of the negative biopsies could be eliminated while still detecting 98% carcinomas. CONCLUSIONS: Measurement of f/t PSA reduces the number of unnecessary biopsies in PSA screening without missing many cancers.

Tritium intake by exposure to plastic case watches.

In recent years tritium has been used in plastic case watches as permanent light sources on watch dials. To measure the release of tritium through the plastic cases, 82 different waterproofed watches were immersed in a water bath for 24 h, and the tritium concentration of the water was measured. The mean tritium release rate was 24,400 Bq d(-1) ranging from 110-162,000 Bq d(-1). Parallel measurements were made to determine the tritium concentration in the urine of 108 wearers of plastic case watches. The mean tritium concentration in urine was 197 Bq L(-1) up to 1,133 Bq L(-1). The whole body dose resulting from exposure to plastic case is negligibly small but given the pathway of skin absorption, the annual skin dose is 3-4 times higher than the dose limit for the public. Plastic case watches are collector's items and are often kept with other watches in glass cabinets or other containers. Storage of a large number of such watches in one container causes tritium to diffuse through the plastic cases and to contaminate watches that did not contain tritium at first. If the container is more or less airtight, the tritium concentration in the container and the tritium release rate from the watches can reach levels up to 4 MBq d(-1).

Comparison of different prostate-specific antigen cutpoints for early detection of prostate cancer: results of a large screening study.

OBJECTIVES: This study was designed to compare the usefulness of the normal prostate-specific antigen (PSA) level and the age-referenced PSA level in a large screening study for early detection of prostate cancer. METHODS: A total of 21,078 subjects (aged 45 to 75 years) were participants in a 1-year prostate cancer screening project with PSA as the initial test. Of the volunteers, 1618 (8%) showed an elevated PSA level according to age-specific reference ranges, and using the normal PSA cutoff point (4.0 ng/mL), 1872 (9%) had elevated PSA levels between 4.0 and 6.5 ng/mL. RESULTS: Biopsies in both groups were performed if the PSA level was elevated. We evaluated the effect on biopsy rate and cancer detection. A PSA cutoff point of 2.5 ng/mL in men 45 to 49 years old and a PSA cutoff point of 3.5 ng/mL in men 50 to 59 years old with normal digital rectal examination findings resulted in an 8% increase in the number of biopsies (66 of 778) and an 8% increase in organ-confined cancer detection. An increasing cutoff of 4.5 ng/mL in men 60 to 69 years old and 6.5 ng/mL in men 70 to 75 years old resulted in 21% fewer biopsies (205 of 983) and would have missed 4% of organ-confined tumors (8 of 220). CONCLUSIONS: We conclude that the use of PSA age-specific reference ranges increases the detection of clinically important and organ-confined cancers in young men and decreases the number of biopsies in older men.

Mitigation of indoor radon in an area with unusually high radon concentrations.

In an area of unusually high indoor radon concentrations of up to 270,000 Bq m-3, four houses were selected for mitigation of indoor radon. Methods used were basement sealing, soil depressurization, a mechanical intake and outlet ventilation system with heat exchanger in the basement, and a multilayer floor construction using a fan to suck radon from a layer between bottom slab and floor. Basement sealing proved unsuccessful, the radon concentration remained unchanged after the mitigation attempt. The most successful remedial measure was soil depressurization using two fans and loops of drainage tubes to withdraw radon from the region under the floor and outside the walls of the basement and from soil under the part of the house without a basement. This method reduced the basement radon level in winter by about a factor of 200, i.e., from 100,000 Bq m-3 to 500 Bq m-3, and the ground-floor level by about a factor of 400. As regards the mechanical intake and outlet ventilation system with heat exchanger in the basement, it is essential to ensure that ventilation provides increased air pressure in the basement compared to outdoors. Unbalanced mechanical intake and outlet ventilation may decrease the air pressure indoors compared to outdoors, leading to increased radon concentrations. Optimization of this method reduced radon concentrations from 200,000 Bq m-3 to 2,000-3,000 Bq m-3 in winter. In one house with only a very small basement, a multilayer floor construction using a fan to suck radon from a layer between the bottom slab and floor was found to reduce radon concentrations on the ground floor from 25,000 Bq m-3 to about 1,700 Bq m-3 in winter. The results show that even in areas with extremely high radon concentrations, effective mitigation of indoor radon can be accomplished if suitable techniques are used. The evaluation of the different mitigation methods shows good coincidence with the ICRP 65 report.

Iatrogenic ruptures of the stomach after balloon tamponade. Two case reports: viscoelastic model.

Two cases of gastric rupture as a rare complication of balloon tamponade for esophageal varices are presented. In both cases, the rupture was caused by instillation of irrigation fluid without previous aspiration of stomach contents. In an experimental study, the stomachs of 11 corpses were filled with water to determine rupture pressure and volume. The mean rupture pressure was 73 +/- 13 mm Hg (9.7 +/- 1.7 kPa) and the mean rupture volume was 2,670 +/- 410 ml. A viscoelastic model was used for the representation of the relations between pressure and volume as well as pressure and time. Measured values are significant particularly for the explanation and medicolegal evaluation of iatrogenic ruptures of the stomach that occur during gastric lavage, positive pressure respiration, incorrect intubation, or forced mask respiration during resuscitation.

High indoor radon concentrations in an Alpine region of western Tyrol.

In a village in western Tyrol, Austria (Umhausen, 2,600 inhabitants), unusually high indoor radon concentrations were measured, and the lung cancer mortality rate was found to be higher than that of the total population of Tyrol (620,000 inhabitants). Annual means of radon concentrations were found to be particularly high in the area between the two rivers Otztaler Ache and Hairlachbach, geologically an alluvial fan of a giant rock slide of granitic gneisses (area A, median of annual means on the ground floors: 1,868 Bq m-3); radon concentrations were comparatively low in the rest of the village (area B, median of annual means on the ground floors: 182 Bq m-3). On the basis of these medians, the annual exposures were calculated according to the ICRP model (area A: 58.8 x 10(5) Bq h m-3; area B: 5.7 x 10(5) Bq h m-3). Data taken from the Cancer Registry of Tyrol were used to determine the age- and sex-standardized lung cancer mortality rate (area A: 6.17; area B: 1.43).

Unusually high indoor radon concentrations from a giant rock slide.

In a village in western Tyrol, Austria (Umhausen, approximately 2600 inhabitants) unusually high indoor radon concentrations were measured. The medians were found to be 3750 Bq/m3 (basements) and 1160 Bq/m3 (ground floors) in winter, and 361 Bq/m3 (basements) and 210 Bq/m3 (ground floors) in summer. Maximum radon concentrations of up to 274,000 Bq/m3 were registered. The unusually high radon concentrations are due to the geology of the locality. The part of Umhausen with the highest radon concentrations is built on an alluvial fan of a giant rock slide (granitic gneiss). Measurements of the radon exhalation rate from soil showed a median of 0.4 Bq/m2/s, measurements of the radium content of rock samples yielded a median of 125 Bq/kg. The material of the rock slide is heavily fractured so that an elevated emanating power and an increased diffusion coefficient for radon in soil must be assumed. Given a diffusion coefficient of 8 x 10(-6) m2/s and an emanating power of 0.3, the median exhalation rate of 0.4 Bq/m2/s is obtained at a radium concentration of 125 Bq/kg. The rock slide is therefore considered to be the main source of radon. The abnormally high radon concentrations in Umhausen coincide with a statistically significant increase in lung cancer mortality (age and sex standardized mortality rate = 3.9, 95% C.I.: 2.9-5.1); the control population is the population of the entire Tyrol (630,000 inhabitants).

Vasomotion induces regular major oscillations in jejunal mucosal tissue oxygenation.

The mucosa of the small intestine has some unique microcirculatory features that may result in significant tissue oxygenation changes even under physiological conditions. To prove this hypothesis we investigated mucosal and serosal oxygenation in an autoperfused, innervated jejunal segment in pigs. Eight animals (30-40 kg) were anesthetized, paralyzed, and normoventilated. A small segment of the jejunal mucosa and serosa was exposed by a midline laparotomy and an antimesenteric incision. Mucosal and serosal oxygen tensions were measured using Clark-type surface oxygen electrodes. Mucosal hemoglobin saturation and concentration were determined by tissue reflectance spectrophotometry. Systemic hemodynamics, mesenteric-venous acid base, and blood gas variables, as well as systemic acid-base and blood gas variables and jejunal electromyogenic potentials, were recorded. Measurements were performed after a rest period at 0, 30, 60, and 90 min. All animals remained hemodynamically stable. At time 0 the jejunal oxygen extraction ratio was 0.33 +/- 0.05, the mean serosal PO2 was 60.25 +/- 7.69, the mean mucosal PO2 was 25.47 +/- 4.41 mmHg, and the mean mucosal hemoglobin saturation was 46.36 +/- 6.22%. Mean values did not change with time. In contrast to serosal PO2, mucosal PO2, mucosal hemoglobin oxygen saturation, and hemoglobin concentration showed rhythmic oscillations with a frequency of 3.4-5 cycles/min that were unrelated to systemic hemodynamic parameters, respiratory frequency, and intestinal peristalsis. From this we concluded that the jejunal mucosa demonstrates significant, regular changes in oxygenation parameters that are locally mediated. We speculate that the physiological basis for this phenomenon is the countercurrent arrangement of microvessels in conjunction with vasomotion.(ABSTRACT TRUNCATED AT 250 WORDS)

[Sound frequency analysis for identification of venous air embolism]. / Frequenzanalyse von Geräuschen zur Erkennung von venösen Luftembolien.

Air emboli occurring during surgery are considered to be life-threatening incidents. With the aim of achieving acoustic identification of venous air emboli, a frequency analysis of the sounds induced by an air embolism (millwheel murmurs) as well as of all other unusual sounds, was undertaken during 20 operations, and in experiments with animals. The frequency spectra of the sounds induced by air emboli are characterised by an increase in the amplitudes in the frequency range 1,100 to 3,000 Hz, while the amplitudes of normal heart sounds continuously decrease with increasing frequency. The frequency spectrum was examined for characteristics using an electronic filter system. The sounds induced by air emboli can be clearly distinguished from normal heart sounds. During operations on patients, suction sounds occur, the frequency patterns of which are not easy to distinguish from those of embolus-induced sounds, although an acoustic distinction can be made via a stethoscope or a loudspeaker. With optimal adjustment of the filter system, 73 out of 81 (90%) embolism-related sounds were correctly identified in animal experiments. On no occasion were normal heart sounds wrongly identified as due to an embolus. However, an embolus sound was frequently mimicked by interfering sounds such as those produced by artificial respiration, and other ambiend sounds. By modifying the oesophageal catheter to achieve optimal suppression of interfering sounds, this filter system could be developed into an alarm.

[Modified retroperitoneal lymph node excision in testicular tumors. Anatomy, surgical technique and results]. / Modifizierte retroperitoneale Lymphadenektomie bei Hodentumoren. Anatomie, Operationstechnik und Ergebnisse.

Between January 1988 and June 1992, 56 patients suffering from malignant testicular tumors underwent nerve-preserving retroperitoneal lymphadenectomy at the University Hospital in Innsbruck. The tumors were staged according to the nomenclature recommended by the Workshop for Staging and Treatment of Testicular Cancer (Lugano 1979). According to this nomenclature 23 patients had stage I and 33 patients stage II. Thirty-nine patients presented with malignant teratoma, 3 with seminoma and 14 with teratoma and seminoma. The patients with stage I tumors were treated after orchiectomy with nerve-preserving retroperitoneal lymphadenectomy according to the dissection fields of Weissbach et al. In cases of nodal involvement in the retroperitoneum (stage IIa and IIb) a retroperitoneal modified lymphadenectomy according to the margins of Colleselli et al was performed. Patients with stage IIc tumors were treated with three cycles of polychemotherapy. Subsequently, the residual tumor was removed and, if possible, a nerve-sparing lymphadenectomy was performed. Since the nerve-preserving technique was modified in accordance with the tumor stage, antegrade ejaculation could be preserved in 47 of the 56 patients. In 22 patients exocrine testicular function was assessed by sperm analysis. The findings for the patients with stage I and IIa were considerable. The patients who had undergone induction chemotherapy for stage IIb and IIc had poor exocrine testicular function. The follow-up time was 29 months. At follow-up none of the patients presented with recurrent retroperitoneal tumor. Only one patient was found to have tumor progression (solitary pulmonary metastasis 1.7%). These results show that nerve-preserving retroperitoneal lymphadenectomy is the treatment of choice in stage I non-seminomatous testicular tumors.(ABSTRACT TRUNCATED AT 250 WORDS)