Furusawa, Y., Fukutsu, K., Aoki, M., Itsukaichi, H., Eguchi-Kasai, Ohara, Yatagai, F., Kanai, T. and Ando, K. Inactivation of Aerobic Hypoxic Cells from Three Different Cell Lines by Accelerated 3He-, 12C- 20Ne-Ion Beams.The LET-RBE spectra for cell killing cultured mammalian cells exposed to accelerated heavy ions were investigated design a spread-out Bragg peak beam cancer therapy at HIMAC, National Institute Radiological Sciences, Chiba, prior clinical trials. that originated human...

Data on cellular inactivation resulting from mixed irradiation with charged-particle beams of different linear energy transfer (LET) are needed to design a spread-out Bragg peak (SOBP) for heavy-ion radiotherapy. The present study was designed the relationship between physical and biological (cell killing) properties by using monoenergetic 3He, 4He 12C ions (12 18.5 MeV/nucleon) attempt apply experimental data in SOBP (3 cm width) 135 MeV/nucleon carbon beam. Experimental studies...

Recently, the use of gold nanoparticles as potential tumor selective radiosensitizers has been proposed a breakthrough in radiotherapy. Experiments living cells and vivo have demonstrated efficiency metal when combined with low energy x-ray radiations (below conventional 1 MeV Linac radiation). Further studies on DNA performed order to better understand fundamental processes sensitization further improve method. In this work, we propose new strategy based combination platinum irradiation by...

We describe a method to calculate the relative biological effectiveness in mixed radiation fields of therapeutic ion beams based on modified microdosimetric kinetic model (modified MKM). In addition, we show procedure for integrating MKM into treatment planning system scanned carbon beam. With this procedure, is fully integrated our research version system. To account change radiosensitivity cell line, measured one three parameters from single survival curve current cells and used parameter...

Kase, Y., Kanai, T., Matsumoto, Furusawa, Okamoto, H., Asaba, Sakama, M. and Shinoda, H. Microdosimetric Measurements Estimation of Human Cell Survival for Heavy-Ion Beams. Radiat. Res. 166, 629–638 (2006).The microdosimetric spectra high-energy beams photons proton, helium, carbon, neon, silicon iron ions (LET = 0.5–880 keV/μm) were measured with a spherical-walled tissue-equivalent proportional counter at various depths in plastic phantom. curves human tumor cells also obtained under the...

Abstract Particle radiotherapy such as proton and carbon ion has been producing promising clinical results worldwide. The purpose of this study was to compare metastatic capabilities malignant tumor cells after irradiation with photon, proton, beams clarify their beam–specific biological effects. We examined the properties highly aggressive HT1080 human fibrosarcoma assess processes in terms cell adhesion capability extracellular matrix, expression integrins, migration, invasive capability,...

Both the microdosimetric kinetic model (MKM) and local effect (LEM) can be used to calculate surviving fraction of cells irradiated by high-energy ion beams. In this study, amorphous track structure models instead stochastic energy deposition are for MKM calculation, it is found that calculation useful predicting survival curves mammalian in vitro (3)He-, (12)C- (20)Ne-ion The also calculated two different implementations LEM, which inherently an model. results manner show good agreement...

Abstract Solid tumours often present regions with severe oxygen deprivation (hypoxia), which are resistant to both chemotherapy and radiotherapy. Increased radiosensitivity as a function of the concentration is well described for X-rays. It has also been demonstrated that radioresistance in anoxia reduced using high-LET radiation rather than conventional However, dependence enhancement ratio (OER) on quality intermediate concentrations, those normally found tumours, had never measured...

The biological effects of radiation originate principally in damages to DNA. DNA by X rays as well heavy ions are induced a combination direct and indirect actions. contribution action cell killing can be estimated from the maximum degree protection dimethylsulfoxide (DMSO), which suppresses without affecting action. Exponentially growing Chinese hamster V79 cells were exposed high-LET radiations 20 2106 keV/mum presence or absence DMSO their survival was determined using colony formation...

Although carbon ion therapy facilities are expensive, the biological effects of beam treatment may be better against cancer (and stem cells) than a photon beam. To investigate whether have advantage over X-rays by targeting stem-like cells, human colon cells were used in vitro and vivo. The relative effectiveness (RBE) values to at D10 from 1.63 1.74. Cancer CD133(+), CD44(+)/ESA(+) had greater ability for colony spheroid formation, as well vivo tumorigenicity compared with CD133(-),...

Purpose : To investigate the signal factor and its function in medium-mediated bystander effect during heavy-ion irradiation of human salivary gland (HSG) neoplastic cells. Materials methods Unirradiated recipient HSG cells were co-cultivated with donor irradiated 290 MeV/u carbon beams having different LET values. Cell proliferation micronucleus (MN) induction without treatment a NO scavenger (PTIO) measured concentration nitrite co-culture medium was detected. As direct control, effects...

The possible mechanism of a radiation-induced bystander response was investigated by using high-LET heavy particle microbeam, which allows selected cells to be individually hit with precise numbered particles. Even when only single cell within the confluent culture one 40Ar (approximately 1260 keV/microm) or 20Ne 380 keV/microm), 1.4-fold increase micronuclei (MN) detected demonstrating response. When number targeted increased, MN biphasically increased; however, efficiency induction per...

Estimation of the survival fractions cells irradiated with various particles over a wide linear energy transfer (LET) range is great importance in treatment planning charged-particle therapy. Two computational models were developed for estimating based on concept microdosimetric kinetic model. They designated as double-stochastic and stochastic models. The former model takes into account natures both domain cell nucleus specific energies, whereas latter represents nature by its approximated...

Involvement of gap junctional intercellular communication (GJIC) in bystander responses confluent human fibroblasts irradiated with a carbon-ion beam was investigated. It found that the lower radiation dose, higher yield radiation-induced micronuclei per nuclear traversal, suggesting existence effects. This low-dose sensitivity increased when GJIC enhanced by treating cells 8-Br-cAMP, but it partly reduced DMSO, an effective scavenger reactive oxygen species (ROS). Moreover, no observed were...

We have recently reported the kinetics of chromosome rejoining and exchange formation in human lymphocytes exposed to gamma rays using techniques fluorescence situ hybridization (FISH) premature condensation (PCC). In this paper, we extended previous measurements cells charged particles. Our goal was determine differences chromatin break misrejoining after exposure low- high-linear energy transfer (LET) radiation. Cells were irradiated with hydrogen, neon, carbon or iron ions LET range...

We studied the relation between initial DNA double-strand breaks (DNA-DSB) and rejoining kinetics of strand breaks, as well OER (oxygen enhancement ratio) after low- high-LET (linear energy transfer) radiations. CHO cells were exposed to 200 kVp X-rays or 80 keV/μm carbon ions under oxic hypoxic conditions. DNA-DSB in analyzed by a static-field gel electrophoresis (SFGE). The could be described sum fast slow components. released X-ray irradiation was higher for irradiated an condition than...

Radiation has been shown to enhance intercellular communication in the skin and lungs through an increase of connexin43 (Cx43) expression. If analogous Cx43 up-regulation is induced diseased heart, it would provide a new perspective radiation therapy for arrhythmias. The aim present study test this hypothesis.Non-transmural myocardial infarction (MI) was created 24 rabbits by microsphere injection into coronary arteries. Twenty-four without MI were used as controls. Targeted external heavy...

Our cell survival data showed the obvious dependence of RBE on photon energy: The value for 200 kV X-rays was approximately 10% greater than those mega-voltage beams. In radiation therapy using beams, energy distribution outside field is different with that in because a large number low scattering photons. Hence, values become greater. To evaluate increase RBE, method deriving Microdosimetric Kinetic model (MK model) proposed this study. MK has two kinds parameters, tissue-specific...

DNA double-strand breaks (DSBs) induced by ionizing radiation pose a major threat to cell survival. The can respond the presence of DSBs through two repair pathways: homologous recombination (HR) and nonhomologous end joining (NHEJ). Higher levels death are high-linear energy transfer (LET) when compared low-LET radiation, even at same physical doses, due less effective efficient repair. To clarify whether high-LET inhibits all pathways or specifically one pathway, studies were designed...

In the clinic, relative biological effectiveness (RBE) value of 1.1 has usually been used in relation to whole depth spread-out Bragg-peak (SOBP) proton beams. The aim this study was confirm actual effect SOBP at very distal end clinical beams using an vitro cell system. A human salivary gland tumor line, HSG, irradiated with (accelerated by 190 MeV/u) and examined different depths part center SOBP. Surviving fractions were analyzed colony formation assay. Cell survival curves parameters...