Heavy charged particle radiobiology: Using enhanced biological effectiveness and improved beam focusing to advance cancer therapy

Department of Environmental and Radiological Health Sciences, Colorado State University, Ft. Collins, CO 80523, USA.
Mutation Research/Fundamental and Molecular Mechanisms of Mutagenesis (Impact Factor: 3.68). 03/2011; 711(1-2):150-7. DOI: 10.1016/j.mrfmmm.2011.02.012
Source: PubMed


Ionizing radiation causes many types of DNA damage, including base damage and single- and double-strand breaks. Photons, including X-rays and γ-rays, are the most widely used type of ionizing radiation in radiobiology experiments, and in radiation cancer therapy. Charged particles, including protons and carbon ions, are seeing increased use as an alternative therapeutic modality. Although the facilities needed to produce high energy charged particle beams are more costly than photon facilities, particle therapy has shown improved cancer survival rates, reflecting more highly focused dose distributions and more severe DNA damage to tumor cells. Despite early successes of charged particle radiotherapy, there is room for further improvement, and much remains to be learned about normal and cancer cell responses to charged particle radiation.

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Available from: Jac Nickoloff, Nov 13, 2014
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    • "The particle beam energy distribution is somewhat different than X-rays and photon beams. The particle beam penetrates deep inside the body (penetration depth depends upon the energy of the beam), at particular depths they give off about 99% of their total energy and then extinguish [7]. This feature is very helpful in targeting the infected tissues without affecting the healthy ones. "
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    • "Interestingly, these cells showed differential responses to genotoxic stress induced by photon (X-ray) irradiation or particle ion beams. Compared to photons, carbon ion beams deliver a larger mean energy per unit length of their trajectory [8] [9]. The relative biological effectiveness of carbon ion beams with respect to reference photon radiation is estimated to be approximately 2–3-fold, as assessed by biological endpoints such as cell death, DNA damage, and chromosomal aberrations, among others. "

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    • "This is why X-rays and γ-rays are considered sparsely ionizing, or low-linear energy transfer (LET), forms of IR. On the other hand, particulate forms of ionizing radiation such as neutrons, α particles, or carbon ions, are considered densely ionizing, or high LET, forms of radiation because they ionize along their tracks at a higher rate than the electrons generated by X-rays (64). "
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