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Biomedical subjects

D Hebbinghaus

Publications and source records attributed to D Hebbinghaus.

18 recordsLinked to original sources
PubMed1998

[A new method of 3-dimensional imaging of dose distribution in radiotherapy].

Beside the documentation it is the object of the graphical presentation of dose distribution in radiotherapy to clarify for better judgement. A three-dimensional graphical presentation could rise the understanding. Auto-stereographical presentation of isodoses opens the practicability for a three-dimensional view without the use of additional auxiliarities, such as stereoscope, or spectacles. This is shown by some isodose distribution charts (fixed field-, box-, multiple field- and rotation-technique, AL-treatment).

Dose Fractionation, Radiation↗
PubMed1996

Conformal treatment planning for interstitial brachytherapy.

PURPOSE: Quality of a brachytherapy application depends on the choice of the target volume, on the dose distribution homogeneity and radiation injury on critical tissue, which should be postulated by advanced brachytherapy treatment planning systems. MATERIAL AND METHODS: Basic imaging method for conformal treatment planning is the cross-sectional imaging. The clinical applicability of a new type 3D planning system using CT and/or MRT-simulation or US-simulation for planning purposes was studied. The planning system developed at Kiel University differs from usual brachytherapy planning systems because of the obligatory use of cross-sectional imaging as basic imaging method for reconstruction of structures of interest. Dose distribution and normal anatomy can be visualized on each CT/MRT/US slice as well as coronal, sagittal, axial and free chosen reconstruction (3D), as well as dose-volume histogram curves and special colour-coded visualization of dose homogeneity in the target can be analyzed. RESULTS: Because of the experience in the clinical routine, as well as on the base of 30 simultaneous planning procedures on both 2D (semi-3D) and 3D planning systems we observed similar time consumption. Advantages of 3D planning were the better interpretation of target delineation, delineation of critical structures as well as dose distribution, causing more accurate volume optimisation of dose distribution. CONCLUSION: Conformal brachytherapy treatment planning for interstitial brachytherapy means significant advantages for the clinical routine compared to 2D or semi-3D methods.

Algorithms↗
PubMed1995

[The new possibilities of digital luminescence radiography (DLR) and digital imaging data processing for the making of field verification images].

BACKGROUND: Treatment verification for reasons of quality control takes an important place in daily radiotherapeutic work. The quality of conventional, e.g. not digital imaging methods, is often poor. Moreover, portal and verification imaging are commonly used only for photon beam control; even digital portal radiographs were not suitable for verification of electron beams, rotation beams, conformation therapy or dynamic multileaf collimation yet. MATERIALS AND METHODS: We developed a method, using digital luminescence radiography (DLR), not only for portal imaging of photon beams in an excellent quality, but also for verification of electron beams. Further on, DLR was used as basic instrument for image fusion of portal and verification film and simulation film respectively for image processing in "beams-eye-view" verification (BEVV) of rotating beams or conformation therapy. RESULTS: Digital radiographs of an excellent quality are gained for verification of photon and electron beams. In photon beams, quality improvement vs. conventional portal imaging may be dramatic, even more for high energy beams (e.g. 15-MV-photon beams) than for Co-60. In electron beams, excellent results may be easily obtained. By digital image fusion of 1 or more verification films on simulation film or MRI-planning film, more precise judgement even on small differences between simulation and verification films becomes possible. Using BEVV, it is possible to compare computer aided simulation in rotating beams or conformation therapy with the really applied treatment. The basic principle of BEVV is also suitable for dynamic multileaf collimation. CONCLUSIONS: DLR is a multipotent and suitable method for many aspects of imaging treatment verification.

Electrons↗
PubMed1988

[Field-integrated dosage modification (FIDM). 2. The physical principles of the procedure].

A method is suggested and described which allows to introduce areas of different sizes, shapes, sites, and doses into a photon irradiation field. The bases for calculation and manufacturing of such irregular field stops containing integrated dose modification blocks are, according to precision requirements and data acquisition possibilities, either information provided by computed tomography or conventional planning radiographs. The following standard parameters are required as input data: sizes, shapes, and positions of the partial fields within the total irradiation field, depth of the reference plane, absorption coefficient of the modification material used, proportions of the planned dose modification, radiation quality, and other radiation field parameters. For the calculation of the dose distributions within the generally irregularly shaped irradiation volumes, an iterative algorithm has been formulated following the differential sector addition method and an equivalent TAR scheme. The quality of such a modifier can be checked by standard dosimetric methods. Deviations from the planned dose modification can be defined as sigma = +/- 5% for the radiation qualities employed (60Co gamma radiation and 15 MeV bremsstrahlung of a linear accelerator).

Gamma Rays↗
PubMed1987

[Clinically-oriented hints for the technic of integrated dosage modification in a partial irradiation field].

The authors present a method allowing the application of doses differing from the reference dose in partial zones of an irradiation volume. The compensator-integrated modification is performed by a simultaneous dose harmonization in the reference plane. Three methods are described by which a topographic and anatomic assignment of field and partial field is possible on the basis of the irradiation features. The optimum application of each method in the individual irradiation schemes is discussed.

Humans↗
PubMed1987

[Presentation of a new partial-field blocker for breast-preserving therapy of breast carcinoma].

A combination of conservative surgery and locoregional radiotherapy is a promising conception for conservative treatment of the so-called little mammary carcinoma. As a further increase of the longterm healing rate is probably almost impossible to achieve, changes of the irradiation technique aim at present only to improve the irradiation quality. With this background, the authors have developed a partial field blocker considering the anatomic and topographic radiophysical features of this therapy method and making possible furthermore various individual treatment modalities. The construction, function and clinical importance of this partial field blocker are described in detail and the physical parameters changing with respect to open field irradiation are discussed.

Breast Neoplasms↗
PubMed1985

[Allogeneic bone marrow transplantation after fractionated whole body irradiation. Results at the Kiel transplantation center].

Allogeneic bone marrow transplantations were carried out between March 1983 and July 1985 in 31 patients aged 7 to 45 years (median 18 years). Acute lymphoblastic leukaemia in 1st to 5th remission was present in 8 patients, acute myeloblastic leukaemia in 1st and 2nd remission in 4 patients, chronic myeloid leukaemia, with various remission status, in 6 patients, 3 patients had severe aplastic anaemia and there were single cases of myelodysplasia and immature cell megakaryocytic myelosis. Transplantation was carried out during relapse in 8 patients with either acute myeloid or lymphoblastic leukaemia. Phenotypic HLA-identical mothers (n = 2) as well as genotypic HLA-identical siblings (n = 27), and in two cases HLA-non-identical mothers, served as bone marrow donors. In leukaemia patients the conditioning treatment consisted of fractionated total body irradiation and high dose cyclophosphamide or etoposide. Patients with severe aplastic anaemia received cyclophosphamide (4 X 50 mg/kg) and fractionated total nodal irradiation (total dose 8 Gy). 19 patients (61%) survived 14 to 605 days after bone marrow transplantation. 15 patients (48%) continue to remain in complete remission with Karnofsky indices of greater than or equal to 90%. Causes for death were infection (n = 3), interstitial pneumonia (n = 3), relapse (n = 3) as well as single cases involving acute graft-versus-host-disease, non-engraftment of donor marrow and veno-occlusive disease of the liver.

Acyclovir↗
PubMed1985

[Fractionated homogeneous whole body irradiation prior to bone marrow transplantation].

At the University of Kiel, myeloid and acute lymphatic leukemia is treated since 1983 by total-body irradiation applied prior to bone marrow transplantation. Dose deviations in the midplane caused by the irregular surface and tissue inhomogeneities of the patient are reduced down to +/- 3.5% compared to the central ray, with the help of CT-based individual compensators. This method prevents above all an excessive dose to the lungs. The radiobiologic advantages of fractionated irradiation have been employed for all patients treated hitherto (n = 9). At present, a total body dose of 12 Gy in six fractions is applied within three days. There were no undesired acute radiogenic reactions except a mild acute mucositis found in all patients. Chronic side effects, especially in the lungs, were not demonstrated, too. However, the average follow-up time of 149 days has been rather short. One patient died from relapse of leukemia after a total dose of 10 Gy, another patient died because the transplanted bone marrow was rejected, and a third died from catheter sepsis. Six out of nine patients are in complete remission with a maximum index of Karnofsky. The limited experiences gained hitherto show that the homogenous accelerated-fractionated total-body irradiation offers essential advantages compared to non-compensated single dose irradiation with respect to the prevention of undesired radiogenic effects in sound tissues and that its therapeutic efficacy is at least the same.

Adolescent↗
PubMed1984

[Optimization of dose distribution in whole body irradiation by means of compensators].

In case of whole-body irradiation prior to bone marrow graft, an undesired irregular dose deposition in the median body plane is caused by the irregular body shape and the tissue inhomogeneities of the patient, which can amount up to 50% of the planned focal dose in case of laterally opposing irradiation. A procedure is proposed allowing to modify the dose distribution in the irradiated body systematically by means of compensators. Such compensators are produced with the aid of an adequate number of serial CT scans, a programme system considering these data and the individual irradiation geometry, and a computer-controlled cutter working in three dimensions. First a casting mould is manufactured which is then filled up with an adequate compensation material. The actual compensation data and the planned irradiation geometry are controlled before and during the treatment. Taking into consideration the individual shapes and the different tissue densities, it is not only possible to prevent the dose inhomogeneities mentioned above but also to introduce by means of a special programme part regions with a higher or lower dose deposition at any point of the irradiation field, at the therapeutist 's discretion.

Bone Marrow Transplantation↗
PubMed1980

[Automatic image display to static and dynamic scintigrams (author's transl)].

A system is described which makes use of a fully automated image display. In particular, the computer indicates the level of background subtraction and cut-off. For individual scintigraphic problems various modes for documentation, such as positive, negative and zoom displays may be used. The programmer is able to intervene at all stages of the programme. Experience has shown satisfactory results in 80-90%.

Computers↗
PubMed1980

[Practical application of optimization criteria for geometrical distributions of the radiation dose: choice of the irradiation technique in 60Co-teletherapy (author's transl)].

Fifty-four usual cases of radiation therapy were evaluated, comparing the effective surface doses in sound tissues for different irradiation techniques. Irradiation of the esophagus, mediastinum, lung and bladder was calculated for the cross-fire method, 3-field therapy, and monaxial or biaxial pendulum technique. Pendulum irradiation proved superior to multiple-field techniques in all cases. The number of free parameters in computer-assisted relative optimization of dose distributions can be reduced by means of the determination of the irradiation technique.

Cobalt Radioisotopes↗
PubMed1979

[Evaluation of isotope nephrograms by the deconvolution method (author's transl)].

By means of deconvolution, which can be preformed simply with a minicomputer, a new function is derived from the circulation activity time function and the renal activity time function. This function describes the impulse response of the system "Kidney". The activity time functions are determined with a four-probe counter. The impulse response allows statements about the time during which the activity remains in the kidney, the relative blood flow of both kidneys and a so-called passage time distribution. It was also attempted to substitute the circulation activity time function by a derivative of the bladder activity time function.

Humans↗