Micronuclei and cell survival in human liver cancer cells irradiated by 25MeV/u (40)Ar14(+).

Abstract

Heavy ions with high linear energy transfer (LET) have the following advantages as compared with the conventional X-rays and γ-rays therapy: a better physical selectivity, a higher relative biological effectiveness (RBE), a greater therapeutic gain factor (TGF), a smaller oxygen enhancement ratio (OER) for LET > 200 keV/μm, positrons emitted from nuclear reaction products offering the condition of monitoring heavy ion position in tissue, and so on. During the mid 1970s, 450 patients were treated with heavy ions, mostly neon, at the Bevalac of Lawrence Berkeley Laboratory (LBL), United States[1]. Promising results with neon ions were reported when compared with the conventional radiotherapy for soft tissue sarcoma, bone sarcoma and prostate cancer[2,3]. In 1994, the Heavy Ion Medical Accelerator in Chiba (HIMAC) of Japan was designed to deliver beams of ions, helium to argon, to energies in the range of 100 MeV/u-800 MeV/u. Carbon ions were used for clinical treatment. By August 1997, a total of 301 patients had been treated with carbon ions[4]. The treatment was started at GSI, Darmstadt, Germany in December 1997. Two patients suffering from tumors at the base of skull were treated with five and four fractions of carbon ions respectively[5]. In 1995, HIRFL (Heavy Ion Research Facility in Lanzhou, China) began the basic researches of cancer therapy with heavy ions such as carbon, oxygen and argon. In order to collect basic data for clinical therapy, we studied and discussed the dynamic changes of micronuclei and cell survival in human liver cancer cells SMMC-7721 irradiated by 25 MeV/u40-Ar 14+.