Search PubMed⌕ Search

Biomedical subjects

V Sturm

Publications and source records attributed to V Sturm.

At least 73 records · Page 4Linked to original sources
PubMed1989

Incidence of late radiation necrosis with transient mass effect after interstitial low dose rate radiotherapy for cerebral gliomas.

Late radiation necroses constitute a hazard in low dose rate interstitial irradiation for inoperable gliomas. An incidence of 40% (8/20 patients) was found after permanent implantation of Iodine-125 seeds. This finding may even underestimate the real frequency, because follow-up of unaffected patients was shorter than in patients with radiation necrosis. The necrotic reactions caused a transient mass effect, which lead to a significant deterioration of performance scores. Further manifestations of late delayed radiation damage were observed in two patients. The occurrence of radiation necrosis was correlated with total radiation dose, amount of implanted radioactivity, and with velocity of tumour shrinkage. A mechanism underlying the development of radiation necrosis is proposed: A rapid shrinkage of tumour after interstitial Iodine-125 implantation may cause a significant irradiation of surrounding brain tissue, which was initially lying outside the target volume. Since most patients affected by radiation necrosis were children or adolescents, the risk of radiation damage should be minimized. This could probably be achieved either by reduction of irradiation dose, or by using temporary implants of Iodine-125.

Adolescent↗
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↗
PubMed1989

Establishment and characterization of human glioblastoma cell lines in vitro and their xenografts in nude mice.

Human gliomas were grown as permanent tissue cultures and xenografts in nude mice. Growth kinetics, immunohistology and karyotypes were established. One tumor showed a distinct change in its karyotype after only two passages in nude mice; by contrast, no change of immunophenotype occurred during and after in vivo passaging. Treatment of this glioma as xenograft in nude mice revealed a high sensitivity towards single agent treatment with BCNU. In view of the cytologic aberrations, however, this result should be interpreted cautiously with regard to the clinical situation.

Animals↗
PubMed1989

[Stereotactic single-dose irradiation of cerebral angioma].

Angiomas are vascular malformations conceived as congenital anomalies. Surgical excision is the treatment of choice; an alternative is embolization. Radiation therapy is indicated: (1) for angiomas in vital or sensitive regions of the brain where they cannot be excised without the risk of a disabling neurological deficit and (2) for residual angiomas after partial embolization or incomplete surgical removal. The most effective radiotherapy for angiomas is radiosurgery. "Radiosurgery" is a term used for a special concept of radiotherapy. It describes stereotactically guided single high-dose irradiation. Therefore, a linear accelerator was modified at the German Cancer Research Center in Heidelberg. The precise localization of the target point and a steep dose gradient outside the target volume allow application of high doses to the tumor without damage to the surrounding normal brain tissue. Since 1984, in Heidelberg 41 patients with cerebral angiomas have been treated by stereotactic single high-dose irradiation (doses: 10-28 Gy). Eighteen patients were angiographically examined with a follow-up period longer than 18 months. In 7 patients, the pathological vessels was completely obliterated and in 6 partially. There was no change in 6 patients - all of whom received target doses of below 12 Gy.

Adolescent↗
PubMed1989

[Stereotactically targeted radiotherapy of cerebral arteriovenous malformations].

A report is given about radiotherapy in 41 patients suffering from cerebral vessel anomalies. A modified linear accelerator was used in a moving field technique with multiple pendulum planes to apply single doses between 8 and 28 Gy by means of stereotaxis into the angiographically determined target volume. The medium follow-up is 23 months. The latency of radiogenic effects is between one and two years. Radiological controls with an interval of more than 18 months after therapy are available in 17 out of 41 patients. Angiographic investigation showed complete obliterations of pathological vessels in six out of these patients and partial obliterations in six patients; five patients remained unchanged. There were no acute complications. Seven patients presented neurological deficiencies with a latency of 6 to 12 months, however, in all cases but one they regressed completely. Even taking into consideration the small number of patients and the short time of observation, a comparison with the results of other radiotherapeutical proceedings allows to draw the conclusion that the presented technique of stereotaxic convergent-beam irradiation represents a relatively simple, reliable and, in case of precise indication, efficient method for the therapy of cerebral arteriovenous malformations.

Adult↗
PubMed1989

In vitro release and depot effect after intratumoral application of metrizamide-containing liposomes.

The drug release and intratumoral residence time of small and large liposomes composed of saturated phospholipids and cholesterol were measured in vitro and in tumor-bearing rats by computed tomography. The in vitro release of metrizamide at 37 degrees C was higher in tissue fluid than in diluted serum and PBS-buffer. The extent of release was 20%/48 h for the 100 nm-liposomes and 10%/48 h for the 480 nm liposomes. The decrease of x-ray contrast after intratumoral application resulted in a half-life of t50 = 0.05 d for metrizamide solution and t50 = 0.42 d for small liposomes. Large liposomes showed a linear decrease in contrast, the half-life being t50 = 15 d. While small liposomes rapidly leave the tumor, large liposomes rest intact in the tumor for about 30 d. Therefore they fulfill a fundamental prerequisite for intratumoral depots of cytostatics with controlled release.

Animals↗
PubMed1988

Computerized optimization of 125I implants in brain tumors.

A computer program for treatment planning for the interstitial radiotherapy of brain tumors with 125I stereotactic implants is presented. To minimize brain traumatization only 1-3 catheters loaded with several seeds are implanted. It is possible to position the catheters very accurately due to CT guided stereotactic techniques. Precise treatment planning is necessary because of the high dose gradient of the radiation field. Two planning methods are available: conventional planning with interactive optimization of source configurations and an automatic optimization procedure. The goal of optimization is to identify source parameters (catheter positions and seed activities) for which a prescribed dose at the target surface is approximated as closely as possible.

Brachytherapy↗
PubMed1988

Diagnostic value of the stereotactic approach to focal lesions in the deep brain of children and adolescents.

Since it is relatively harmless, stereotactic biopsy has become in recent years a useful method for the diagnostic assessment of lesions deep in the brain, which are not accessible to open surgery. With the aid of stereotaxis, focal lesions only a few millimeters in diameter can be approached in every location in the brain with high precision. Since stereotaxis does not require general anesthesia, or at most requires only a very shallow anesthesia, it can also be applied to young infants or persons of advanced age. Experience with stereotactic biopsy exploration of lesions of various kinds in the deep brain of 74 children and adolescents, out of a sample of 260 patients of all age groups who received stereotactic biopsy, is reported. Our aim is to demonstrate and discuss the advantage of this contemporary method for child neurology and neurosurgery. In many medical centers in the world where stereotactic tumor biopsy has been established, it has become an important criterion for the choice of treatment.

Adolescent↗
PubMed1988

[CT kinetics of intratumor liposome deposits].

CT follow-up studies of liposome-entrapped metrizamide after intraneoplastic injection into neurogenic s.c. rat tumors were performed. By closely resembling clinical examination conditions, the experimental design has proven suitable in determining the in vivo kinetics of these interstitial liposome deposits. When compared to free metrizamide which may be considered an analogue of water-soluble chemotherapeutics, the encapsulation of metrizamide in liposomes resulted in a retarded decline of the contrast enhancement. Diffusion of liposomes could not be detected and the X-ray attenuation values measured within the liposome deposits continuously decreased with time for both types of liposomes. In the case of multilamellar vesicles, this significantly corresponded to a zero order kinetics with a mean halflife of 300 h. An initial increment in the X-ray attenuation of the liposome deposits might be due to the interstitial absorption of the water component of the liposome-dispersion. Because of the pronounced retardation effect of multilamellar liposomes resulting in a 140-fold prolongation of the interstitial retention time of metrizamide and due to their release kinetics these vesicles may be an appropriate carrier system for a local interstitial chemotherapy modality. Small unilamellar vesicles having an interstitial half-life of 14 h may be used as a faster component of a composed therapy system.

Animals↗
PubMed1987

In vitro model for the response to irradiation of different types of human intracranial tumours.

Twenty-seven human low and high grade gliomas and five meningiomas were cultured in vitro as tumour tissue and/or tumour cells. Cell survival or growth was taken as a measure of radiation response. Astrocytomas II-III and glioblastomas manifested individual patterns of radiosensitivity, ranging from 10 to 90 Gy. Meningiomas did not react. Our findings are consistent with the differences in radiosensitivity of human gliomas experienced clinically and corroborate the validity of the in vitro model.

Brain Neoplasms↗
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↗
PubMed1987

Perspectives of radiotherapy.

The 5 years' survival rate of all cancer patients is 35-45%. In that survival rate radiotherapy takes part in 15%. By further development of radiological methods and techniques radiotherapy gains significance in the recent time. Optimizing radiation planning and tactics, all modern imaging techniques are applied consequently. The radiotherapist must be able to asses their immanent specifity which should remain object of the radiological training, even if separated into therapy and diagnostics. Dose distribution is calculated by computer; three-dimensional planning is done in tumors of the mediastinum, oesophagus carcinoma and paraaortic lymphomas. Critical description of radiation techniques, results, problems and prognoses are given by results in tumors of the epipharynx and gastric cancer. After-loading, done until now only in gynaecological tumors, is performed in recurrences of pharyngeal tumors by individually shaped applicators. Reducing the number of therapy failures as well as possible, the application of higher tumor doses, new kinds of rays as neutrons and combinations with physical and chemical methods is outlined. Modifications of radiation volumes are discussed, especially the irradiation of the complete abdomen in ovarian cancer, the irradiation of the complete body surface by electrons in mycosis fungoides, and the total body irradiation prior to autologue bone marrow transplantation. Modifications of fractionation are shown in short-time radiation of bone metastases and single-time radiation of brain lesions. Low penetrating electron therapy facilitates intraoperative single-time irradiation. Because of higher biological efficiency neutrons and heavy ions allow to irradiate low sensible tumors or recurrences embedded in fibrotic tissue respectively. The combination with hyperthermia yields good results in tumors of the head and neck with better local response and total remissions of 59%. There are potentials in synchronising with chemotherapeutics. Remissions of different duration were achieved in 190 patients. Because of neutrotoxicity there are still problems in applicating radiosensitizers. New methods are applied treating endocrine active tumors by labelled hormone precursers.

Brachytherapy↗
PubMed1987

[Intracranial manifestation of lymphomatoid granulomatosis (Liebow's disease)].

An intracranial manifestation of lymphomatoid granulomatosis occurs in 20% of patients. In the case of a 56-year-old patient it is shown that a relative long period can pass from the first neurological symptoms to histological diagnosis by stereotactic brain puncture. Over 15 months, follow-up studies were performed using computed tomography and magnetic resonance.

Brain Diseases↗
PubMed1987

[Cystic craniopharyngiomas: computed tomography in the pretherapeutic evaluation and control of treatment results following intracystic contact irradiation].

A report is given on the treatment planning by computed tomography and monitoring in 37 cases of preponderantly cystic craniopharyngiomas with different solid tumor parts. Colloidal yttrium 90 silicate was used for the intracystic contact irradiation. Two pretherapeutic forms of the solid tumor parts were found in CT examination which correlated with different courses: 1. the polymorphic type and 2. the type with a smooth outline. A posttherapeutic decrease of the cystic volume was observed in 74% of type 1 cases (n = 19) and in 89% of type 2 cases (n = 18). An increase in volume was only found in type 1 (21%). An increase of the solid tumor part was also found exclusively in the polymorphic type (68%). An additional external irradiation should be considered for this CT manifestation of the tumor, as the solid tumor part is not exposed in intracystic contact irradiation.

Brachytherapy↗
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

Neurosurgical treatment of cancer pain.

Neurosurgical pain operations in carcinoma patients should always be considered when conservative treatment methods fail or pain relief can be attained only at the cost of undesired side effects. The therapeutic spectrum of neurosurgery has been appreciably extended in recent years. Due to the introduction of percutaneous surgery methods, the operations have become less burdensome, so that carcinoma patients who were formerly regarded as inoperable can also be given neurosurgical pain treatment. The advances in neurophysiology have led to a better understanding of pain mechanisms, in consequence of which the various possibilities of treatment can be employed more specifically with prospects of better treatment results. The spectrum of neurosurgical treatment extends from destructive measures (rhizotomies, cordotomies, thalamotomies, neurolytics) via intrathecal administration of morphine-like substances to the augmentative nondestructive neurostimulation techniques. Despite the advances in conservative therapy of cancer pain, in many cases, a neurosurgical procedure is most efficacious in controlling carcinoma pain.

Cordotomy↗
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↗