Search results for "radiobiology"
showing 10 items of 13 documents
Differential Superiority of Heavy Charged-Particle Irradiation to X-Rays: Studies on Biological Effectiveness and Side Effect Mechanisms in Multicell…
2016
This review is focused on the radiobiology of carbon ions compared to X-rays using multicellular models of tumors and normal mucosa. The first part summarizes basic radiobiological effects, as observed in cancer cells. The second, more clinically oriented part of the review, deals with radiation-induced cell migration and mucositis. Multicellular spheroids from V79 hamster cells were irradiated with X-rays or carbon ions under ambient or restricted oxygen supply conditions. Reliable oxygen enhancement ratios could be derived to be 2.9, 2.8, and 1.4 for irradiation with photons, (12)C(+6) in the plateau region, and (12)C(+6) in the Bragg peak, respectively. Similarly, a relative biological e…
Retrospective dosimetry for Latvian workers at Chernobyl.
2001
Between 1986 and 1991 approximately 6500 Latvian inhabitants were recruited for clean-up work at the Chernobyl nuclear power plant. Their absorbed doses are usually unknown, because less than half of them had their external exposure officially documented. Clinical investigations show a high morbidity rate for these clean-up workers when compared with that of the general population. In order to understand the causes of their diseases and the impact of ionising radiation, electron spin resonance (ESR) has been used to measure the absorbed doses in human tooth enamel. The doses estimated by ESR were between two and three times higher than previously documented and are in accord with the result…
Tissue gradients of energy metabolites mirror oxygen tension gradients in a rat mammary carcinoma model
2001
Abstract Purpose: It has been shown that oxygen gradients exist in R3230AC tumors grown in window chambers. The fascial surface is better oxygenated than the tumor surface. The purpose of the present study was to determine whether gradients exist for energy metabolites and other end points related to oxygen transport. Methods and Materials: Imaging bioluminescence was used to measure ATP, glucose, and lactate in cryosections of R3230AC tumors. Mean vessel density and hypoxic tissue fraction were assessed using immunohistochemistry. Tumor redox ratio was assessed by redox ratio scanning. Results: Lactate content and hypoxic fraction increased, whereas ATP, glucose, redox ratio, and vessel de…
Eine neue experimentelle Methode zur Behandlung von Beckenwandrezidiven gynäkologischer Malignome
1989
Pelvic side wall recurrences of gynecological malignancies subsequent to primary or adjuvant radiation therapy have a bad prognosis, although in almost half of the cases, distant metastases are not present at the time of diagnosis of the local tumor progression. A radical operative resection of the pelvic wall recurrence is rarely possible and a second conventional percutaneous or intracavitary irradiation with a tumoricidal dose is no longer feasible, because of the limited radiation tolerance of the surrounding pelvic tissue. The different forms of chemotherapy applied at present are not curative. Based on considerations of tumor and radiation biology, we propose a new experimental treatm…
Hadron therapy information sharing prototype
2013
The European PARTNER project developed a prototypical system for sharing hadron therapy data. This system allows doctors and patients to record and report treatment-related events during and after hadron therapy. It presents doctors and statisticians with an integrated view of adverse events across institutions, using open-source components for data federation, semantics, and analysis. There is a particular emphasis upon semantic consistency, achieved through intelligent, annotated form designs. The system as presented is ready for use in a clinical setting, and amenable to further customization. The essential contribution of the work reported here lies in the novel data integration and rep…
Quantitative changes of metabolic and bioenergetic parameters in experimental tumors during fractionated irradiation.
1999
Abstract Purpose: Previous studies with rat rhabdomyosarcomas indicate that during fractionated irradiation profound alterations of the tumor microvasculature and the oxygenation status occur when the total dose exceeds 45 Gy. At this dose a destruction which included all structures of the vessels and a significant worsening in tumor oxygenation were found. The aim of the present study was to analyze whether these effects of fractionated irradiation on the microvasculature and on tumor oxygenation also induce changes in the bioenergetic and metabolic status in the tumors during radiation treatment. Methods and Materials: R1H rhabdomyosarcomas of the rat implanted into the flank were irradia…
Alpha emitting nuclides in nuclear medicine theranostics.
2021
Theranostic applications with radio-isotopes currently are rapidly progressing and expand nuclear medicine application in clinical routine. Alpha emitting isotopes, in particular, have long been hypothesized to achieve relevant advances for the treatment of malignancies. Here, an overview of their properties and the knowledge of radiobiology is reviewed in view of clinical translation. Clinical evidence of radiopharmaceuticals based on alpha emitters is summarized with a focus on recent developments for treatment of metastasized castration resistant prostate cancer.Theranostische Anwendungen mit Radioisotopen machen derzeit rasche Fortschritte und erweitern den Einsatz der Nuklearmedizin in…
Is high dose rate brachytherapy reliable and effective treatment for prostate cancer patients? A review of the literature.
2014
The intrinsic physical and radiobiological characteristics of High Dose Rate Brachytherapy (HDR-BT) are well suited to the treatment of prostate cancer. HDR-BT was initially used as a boost to external beam brachytherapy, but has subsequently been employed as the sole treatment, which is termed HDR monotherapy. This review summarizes the clinical outcomes and toxicity results of the principal studies and discusses the radiobiological basis supporting its use.
Radiobiological characterization of human tumor cell multilayers after conventional and particle irradiation.
2006
The goal of this study was to establish planar multilayers from human tumor cells (WiDr and SiHa) as a model for irradiation of solid tumors. In addition to using conventional X rays (250 kV) as a reference standard, multilayers were tested for their suitability in cell survival studies with heavy-ion irradiation ((12)C(6+)) in the plateau and the extended Bragg peak with a scanned ion beam. Multilayers of both cell lines showed decreased survival compared to the corresponding monolayers after both X and heavy-ion irradiation. This multicellular sensitization effect is in contrast to the multicellular resistance or contact effect commonly described in the literature. Flow cytometry measurem…
The Role of Oxygen Tension Distribution on the Radiation Response of Human Breast Carcinoma
1994
The response of tumors to radiation is heterogeneous even in animal tumor systems where tumors all originate from the same cell culture, are implanted in genetically similar age-matched animals in a constant anatomic locationl. Hence great heterogeneity of response exists even in situations where intrinsic genetic or epigenetic factors are minimally variable. Several metabolic factors are known to influence the probability of tumor control after radiation. These metabolic factors are also known to vary widely between tumors in humans2,3 and even in animal tumor models. Heterogeneous variables include tumor oxygen tension distribution, glutathione content, glucose delivery and utilization ra…