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H von Boetticher

Publications and source records attributed to H von Boetticher.

14 recordsLinked to original sources
PubMed2006

[Optimizing staff radiation protection in radiology by minimizing the effective dose].

PURPOSE: In the present study the optimization of radiation protection devices is achieved by minimizing the effective dose of the staff members since the stochastic radiation effects correlate to the effective dose. MATERIALS AND METHODS: Radiation exposure dosimetry was performed with TLD measurements using one Alderson Phantom in the patient position and a second phantom in the typical position of the personnel. Various types of protective clothing as well as fixed shields were considered in the calculations. RESULTS: It was shown that the doses of the unshielded organs (thyroid, parts of the active bone marrow) contribute significantly to the effective dose of the staff. Therefore, there is no linear relationship between the shielding factors for protective garments and the effective dose. An additional thyroid protection collar reduces the effective dose by a factor of 1.7 - 3.0. X-ray protective clothing with a 0.35 mm lead equivalent and an additional thyroid protection collar provides better protection against radiation than an apron with a 0.5 mm lead equivalent but no collar. CONCLUSION: The use of thyroid protection collars is an effective preventive measure against exceeding occupational organ dose limits, and a thyroid shield also considerably reduces the effective dose. Therefore, thyroid protection collars should be a required component of anti-X protection.

Health Personnel↗
PubMed2002

Estimation of x ray overexposure in a childhood leukaemia cluster by means of chromosome aberration analysis.

Only multiple X ray diagnostics could be identified as a common risk factor in a leukaemia cluster that appeared between 1985-1989 in the municipality of Sittensen in northern Germany. In order to judge if the effect could be explained by irradiation dose, estimates were done in two of the leukaemia cases and seven former patients of a practice where some of the leukaemia cases had been treated for orthopaedic reasons. The methods used for the reconstruction of doses were physical simulation and biological dosimetry by dicentric chromosomes in peripheral lymphocytes. Compared to the Bremen laboratory control the mean frequency of dicentric chromosomes in the lymphocytes of the seven volunteers was significantly elevated. An overexposure of about 12-fold could be derived compared to state of the art X raying. At least two cases of the leukaemia cluster in Sittensen can therefore be correlated to an overexposure by diagnostic X rays.

Acute Disease↗
PubMed2001

[Radiation exposure in diagnostic radiation: a quantification model for analytic epidemiological studies].

The present paper introduces a model for retrospective assessment of radiation exposure to patients undergoing conventional diagnostic radiography. The model allows for the quantification of relevant organ doses as well as the effective dose from exposures in the time period between 1946 and 1995. The assessment procedure consists of three consecutive steps. The first step uses a set of ideal doses that were measured under optimum conditions. In the second step, we account for the state of radiological technology available at the time of a given exposure. The third step, finally, considers the prevailing standard of radiological practice. Model parameters are derived from a compilation of data from the contemporary radiologic literature as well as from a multitude of historic sources. The three-dimensional matrix of ideal doses and respective correction factors presented here can be readily implemented in the context of analytic epidemiological studies.

Humans↗
PubMed1995

[Thoracic radiography in intensive care units. Comparison of an asymmetric film-screen-grid combination with an L-film].

PURPOSE: Using an asymmetrical screen-film-grid combination with an ITC-VHC special grid (Kodak), the effect of the individual components was evaluated with regard to detail in the lungs and mediastinum as well as patient dose. MATERIALS AND METHODS: The system was compared with the Curix Ortho screen film system (Agfa L-film) using phantoms and 62 patients in an intensive care unit. The results were analysed by three independent observers. Dose measurements on phantoms were carried out with a WD 10 (Wellhoefer) dosimeter and with a thermoluminescence dosimeter for patients. RESULTS: Both phantom and patient images showed improved demonstration of mediastinal structures with similar details of lung structure. Details in the peripheral lungs are significantly better shown with the ITC-VHC system with the special grid than they are without the grid. However, there is an increase about three to four times in radiation dose when using the grid. CONCLUSION: Our trial shows that the use of the ITC-VHC grid system is to be recommended for routine clinical use because of the better demonstration of details, but one must be aware of the increased radiation dose to the patient.

Evaluation Studies as Topic↗
PubMed1994

[A versatile phantom for hemodynamic measurements with ultrasound Doppler equipment].

The test object described comprises a blood simulating liquid pumped through tubes embedded in tissue-mimicking material. The main components of the system can be realised in different ways. They are largely exchangeable with each other. Water, reticulated foam or silicone rubber is used as bulk background material, blood vessels are simulated using latex or silicone tubes or heat-shrink sleeving; in the artificial blood, sephadex particles or silicone emulsion were used as scatterers. The suspension of scattering particles is driven by a roller pump or a membrane dosage pump. The features of the components are described and the applications of the different phantoms discussed.

Blood Flow Velocity↗
PubMed1993

[The determination of the surface and organ doses in the AMBER system. Advanced Multiple Beam Equalization Radiography].

Surface and organ doses were determined by means of thermoluminescence dosimetry with the Alderson-Rando phantom and the patient, for the AMBER thoracic imaging system, sensitivity class 400, and the conventional grid screen stand, sensitivity class 200. The dose on entering the body, which varied according to object-dependent modulation of x-ray intensity, was 140 microGy for the mediastinum and 96 microGy for the lung in p.a. AMBER takes, and hence was comparable with the entrance dose of 132 microGy with the conventional grid screen stand. In lateral takes the entrance doses were lower with the AMBER system (302 microGy) than with conventional takes (593 microGy). Exposure of the gonads at the AMBER system for p.a. thoracic takes was lower than at the screen grid stand in females (4-6 microGy). More unfavourable values were measured for the gonad exposure in males (2-0.8 micrograms).

Humans↗
PubMed1993

[The AMBER thoracic imaging system in routine diagnosis].

After installation of an Amber lung x-ray imaging system the range of application of this technique was registered for two months. Additionally the image quality for structures of the lung parenchyma and mediastinum were proved and dose measurements were performed. 50.6% (772) patients from a total of 1525 could be x-rayed by the Amber imaging system. Related to all people able to stand 73.6% from 1049 patients were examined with the Amber system. Most of the imaging figures of merit specified by the German national physician board were accomplished, besides the fact that 1/3 of the p.a. radiographs were cut off at the side because of the small size of the film. The excellent image of pleuro-mediastinal structures was proofed quantitatively by counting the pleuro-mediastinal lines and comparing the results with standard radiographs. Measuring the exposure at entrance point we obtained nearly the same values for the Amber system using a screen-film combination with a speed of 400 and conventional radiographs (40-120 mu Gy; 21 pat.).

Evaluation Studies as Topic↗
PubMed1992

[The findings of color Doppler sonography in breast tumors].

UNLABELLED: 72 histologically confirmed tumours of the breast--37 carcinomas and 35 benign tumours--for which mammograms were also available were examined by colour Doppler sonography. Vascularisation of benign processes showed at most 2 vessels (with the exception of 3 sarcoma phylloides and one proliferative mastopathy). Vascularisation clearly in excess of benign processes was observed in only 15 of the 37 carcinomas. In 33 of the carcinomas there was no doubt concerning the diagnosis preoperatively, in the remaining 4 the high vascularity was taken as an indication for surgery. CONCLUSION: In rare cases colour Doppler sonography can provide additional information in the presence of 'vascular' tumours. It is not possible to differentiate between poorly vascularised carcinomas and benign tumours.

Adult↗
PubMed1990

[Color-coded Doppler sonographic studies of the morphology and hemodynamics of the pelvic and leg arteries in normal subjects].

An attempt has been made to demonstrate the morphology and haemodynamics of the arteries in the pelvis and lower limbs by means of angiodynography in 20 normal individuals. Problem areas for morphological evaluation are the pelvic vessels, the vessels in the distal adductor canal and the fibular artery in the calf. Haemodynamic studies are successful if the morphology can be adequately shown, but for flow measurements this is true only in the thigh. The results of quantitative haemodynamic analyses are detailed in tabular form (systolic flow -, late systolic reverse and diastolic flow velocity; deceleration; pulsation index; flow values).

Adult↗
PubMed1990

[Phantom measurements of blood flow using color-coded Doppler sonography (Quantum Angiodynograph): accuracy and sources of error].

Flow measurements were carried out on a phantom simulating tissue, using systematic variations of various parameters and of relevant geometric factors. The effect of imaging and flow parameters on the accuracy of the measurements is described and the conditions are defined which are necessary for obtaining a high degree of accuracy. Large errors are introduced by measurements carried out with large Doppler angles or if the delimiters used for automatic vessel measurements have not been set up accurately.

Blood Flow Velocity↗
PubMed1979

Contributions to depth discrimination gamma-gamma-coincidence methods in scintigraphy.

Two problems in the gamma-gamma-coincidence method for depth discrimination in scintigraphy are discussed. Firstly, the FW (1/e)M of the distribution function of time differences between 'coincident' pulses is calculated to be the optimum resolving time for measurement of true coincidences. Secondly, the improvement of time resolution of such an apparatus by substituting a large volume NaI(TI) crystal by an array of many small ones is analysed. It is shown that such arrays will have no practical advantage since the loss in efficiency is of the same order of magnitude as the gain in time resolution.

Mathematics↗