Article

X-ray microbeams: Tumor therapy and central nervous system research

Department of Bio-system Engineering, Yamagata University, Yamagata, Japan
Nuclear Instruments and Methods in Physics Research Section A Accelerators Spectrometers Detectors and Associated Equipment (Impact Factor: 1.32). 09/2005; 548(1-2):30-37. DOI: 10.1016/j.nima.2005.03.062
Source: PubMed

ABSTRACT Irradiation with parallel arrays of thin, planar slices of X-ray beams (microplanar beams, or microbeams) spares normal tissue, including the central nervous system (CNS), and preferentially damages tumors. The effects are mediated, at least in part, by the tissue's microvasculature that seems to effectively repair itself in normal tissue but fails to do so in tumors. Consequently, the therapeutic index of single-fraction unidirectional microbeam irradiations has been shown to be larger than that of single-fraction unidirectional unsegmented beams in treating the intracranial rat 9L gliosarcoma tumor model (9LGS) and the subcutaneous murine mammary carcinoma EMT-6. This paper presents results demonstrating that individual microbeams, or arrays of parallel ones, can also be used for targeted, selective cell ablation in the CNS, and also to induce demyelination. The results highlight the value of the method as a powerful tool for studying the CNS through selective cell ablation, besides its potential as a treatment modality in clinical oncology.

1 Follower
 · 
187 Views
  • [Show abstract] [Hide abstract]
    ABSTRACT: Microbeam radiation therapy (MRT) uses narrow planes of high dose radiation beams to treat cancerous tumors. This experimental therapy method based on synchrotron radiation has been shown to spare normal tissue at up to 1000 Gy of peak entrance dose while still being effective in tumor eradication and extending the lifetime of tumor-bearing small animal models. Motion during treatment can lead to significant movement of microbeam positions resulting in broader beam width and lower peak to valley dose ratio (PVDR), which reduces the effectiveness of MRT. Recently, the authors have demonstrated the feasibility of generating microbeam radiation for small animal treatment using a carbon nanotube (CNT) x-ray source array. The purpose of this study is to incorporate physiological gating to the CNT microbeam irradiator to minimize motion-induced microbeam blurring.
    Medical Physics 08/2014; 41(8):081705. DOI:10.1118/1.4886015 · 3.01 Impact Factor
  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: Radiation has stochastic aspects in its generation, its choice of interaction mode during traveling in media, and its impact on living bodies. In certain circumstances, like in high dose environments resulting from low-LET radiation, the variance in its impact on a target volume is negligible. On the contrary, in low dose environments, especially when they are attributed to high-LET radiation, the impact on the target carries with it a large variance. This variation is more significant for smaller target volumes. Microdosimetric techniques, which have been developed to estimate the distribution of radiation energy deposited to cellular and subcellular-sized targets, contrast with macrodosimetric techniques which count only the average value. Since cells and DNA compounds are the critical targets in human bodies, microdosimetry, or dose estimation by microscopic approach, helps one better analyze the biological effects of radiation on the human body. By utilizing microbeam systems designed for individual cell irradiation, scientists have discovered that human cells exhibit radiosensitive reactions without being hit themselves (bystander effect). During the past 10 or more years, a new therapeutic protocol using discontinuous multiple micro-slit beams has been investigated for its clinical application. It has been suggested that the beneficial bystander effect is the essence of this protocol.
    Nuclear Engineering and Technology 12/2008; 40(7). DOI:10.5516/NET.2008.40.7.551 · 0.76 Impact Factor
  • [Show abstract] [Hide abstract]
    ABSTRACT: Microbeam radiation therapy (MRT) is a promising preclinical modality for cancer treatment, with remarkable preferential tumoricidal effects, that is, tumor eradication without damaging normal tissue functions. Significant lifespan extension has been demonstrated in brain tumor-bearing small animals treated with MRT. So far, MRT experiments can only be performed in a few synchrotron facilities around the world. Limited access to MRT facilities prevents this enormously promising radiotherapy technology from reaching the broader biomedical research community and hinders its potential clinical translation. We recently demonstrated, for the first time, the feasibility of generating microbeam radiation in a laboratory environment using a carbon nanotube x-ray source array and performed initial small animal studies with various brain tumor models. This new nanotechnology-enabled microbeam delivery method, although still in its infancy, has shown promise for achieving comparable therapeutic effects to synchrotron MRT and has offered a potential pathway for clinical translation.
    Expert Review of Anticancer Therapy 11/2014; 14(12):1411-1418. DOI:10.1586/14737140.2014.978293 · 3.06 Impact Factor

Full-text

Download
84 Downloads
Available from
May 31, 2014