Biomedical subjects

O Pastyr

Publications and source records attributed to O Pastyr.

27 records · Page 2Linked to original sources

PubMed1990

[A simple method for positioning and fixing the extremities during the radiotherapy of soft-tissue sarcomas].

The exact and reproducible radiotherapy of malignant tumours in the extremities is aided by reliable positioning of the involved limb. In our department individually-formed casts and circular fix up made of two-component polyurethane foam (NEOFRAKT, supplied by Schumacher, Krefeld, FRG) are used. These allow the maintenance of any bending, stretching and torsional positions. The fields to be applied are cut out of the casts, thus preventing any influence on the depth dose of the radiation involved.

Arm↗

PubMed1989

Stereotactically guided convergent beam irradiation with a linear accelerator: localization-technique.

A stereotactic convergent beam irradiation technique using a linear accelerator has been developed in order to precisely apply single high doses of up to 50 gray and more to brain lesions (radiosurgery). Accurate positioning of the patient and the target point of irradiation is an absolute requirement for this method. The stereotactic localization system developed for this purpose is described.

Humans↗

PubMed1988

Treatment planning for conformation therapy using a multi-leaf collimator.

In high energy photon therapy an optimum dose distribution is achieved with an irradiation from several directions, thus adapting the field shape to the target volume. Some methods of irradiation planning using these techniques are presented. The result of such a treatment planning is demonstrated.

Humans↗

PubMed1987

Stereotactic percutaneous single dose irradiation of brain metastases with a linear accelerator.

The effectivity of stereotactic percutaneous single dose irradiations in the treatment of solitary brain metastases has been assessed in a series of 12 consecutive patients. Only radioresistant deeply localized metastases have been treated. Photon-irradiation was carried out with the convergent beam technique using stereotactic localization methods, in a linear accelerator facility. In 11 of the 12 patients no side effects occurred. The first 7 patients, who could be observed 3 months or longer, have been studied in detail. In each of these cases single dose irradiation with 20-30 Gy yielded arrest of tumor growth. In one case a marked decrease in contrast enhancement and in four cases shrinkage of the metastasis as well as a marked decrease of the edema occurred. In every patient a marked, sometimes dramatic improvement of the clinical condition was achieved, beginning a few days after irradiation. Stereotactic radiosurgery is a valuable tool in the treatment of inoperable, radioresistant brain metastases, the major advantage being high efficacy and smoothness of the procedure, as well as extremely short hospitalization times (2-3 days).

Adult↗

PubMed1985

Cerebral radiation surgery using moving field irradiation at a linear accelerator facility.

A modified irradiation technique at a linear accelerator facility for radiation surgery within the brain is described consisting of several moving field irradiations in non-coplanar planes. Using collimated narrow beams, a localization system and special computer programs for precise patient positioning, a high concentration of dose within small, well circumscribed volumes is obtained. Resulting dose distributions were studied experimentally and by calculations. A simple algorithm for treatment planning was developed and based on CT images. Radiation surgery within the brain is now technically feasible at our linear accelerator. Seventeen patients have now been treated.

Brain↗

PubMed1984

Stereotactic biopsy using computed tomography.

A stereotactic apparatus for percutaneous needle biopsy under computed tomographic (CT) control is described. A program was developed that allows the transfer of CT data to the stereotactic apparatus. No artifacts of the CT images are caused by the stereotactic apparatus. Preliminary results in 36 patients (34 biopsies and two nerve blocks) are reported.

Abdomen↗

PubMed1983

Stereotactic computer tomography with a modified Riechert-Mundinger device as the basis for integrated stereotactic neuroradiological investigations.

For stereotactic biopsy, intracavitary and interstitial irradiation of intracranial tumours, stereotactic CT investigations are of utmost importance. Target-points within a tumour as well as the tumour-outlines have to be transferred precisely from transverse and longitudinal CT sections to stereotactic X-ray images. For this purpose, the stereotactic apparatus of Riechert and Mundinger has been equipped with a fixation system of carbon fibre and a measuring phantoma of plexiglass with embedded steel wires allowing stereotactic CT scanning without artefacts. The stereotactic coordinates (x, y, z) of any target point can be taken directly from transverse CT images with high accuracy. The tumour outlines can be transferred to the stereotactic coordinate system from longitudinal CT reconstructions using special computer programmes. Precise transfer is possible if the CT investigation is performed stereotactically.

Brain Neoplasms↗

PubMedDate not supplied

Interstitial irradiation of cerebral gliomas in childhood by permanently implanted 125-iodine--preliminary results.

19 children with a deeply located cerebral glioma were treated with continuous interstitial irradiation (stereotactically implanted 125-iodine). The accumulated dose at the tumor surface ranged in the low grade glioma group (Group A) from 55 to 100 Gy and in the high grade glioma group (group B) from 50 to 65 Gy. Patients in group B additionally received a fractionated external beam irradiation (15-20 Gy boost dose). Tumor shrinkage as seen on CT-scans 6 months postoperatively could be achieved in 100% of patients with a low grade glioma. The response rate of 6 children with a high grade glioma was 83%. With a mean follow up of 57.0 months (group A) and 56.2 months (group B) respectively the estimated 4.5 year survival probability was 92% for low grade gliomas and 83% for grade III/grade IV lesions. Permanent interstitial irradiation offers the possibility of local tumor control with low risk of severe side effects. The survival rates are promising and comparable with results of other study groups. For gliomas grade I and grade II a dose reduction may be feasible.

Adolescent↗

PubMedDate not supplied

Combined use of stereotaxic CT and angiography for brain biopsies and stereotaxic irradiation.

A Riechert Mundinger stereotaxic device was modified to enable artifact-free computed tomographic (CT) scanning with the stereotaxic frame attached to the patient's head. A localization system was developed allowing determination of the XYZ coordinates of the target point directly from the CT cut. Angiography was performed intraoperatively with the stereotaxic frame attached. Coronal and sagittal CT reconstructions were enlarged to the radiographic magnification to allow direct comparison with angiography. CT offered optimum localization of the target, whereas angiography determined the safest approach. Computer programs were developed to enable three-dimensional radiotherapy planning. 125I seeds were implanted for treatment of low-grade gliomas and solid craniopharyngiomas. Yttrium-90 was applied in cystic craniopharyngiomas. Intracavitary rhenium-186 application was abandoned because of frequent cyst recurrence and leakage from the cyst.

Biopsy, Needle↗