Dosimetry and Apparatus for Heavy Ion Irradiation of Mammalian Cells in Vitro

Experimental techniques are described whereby cultured mammalian cells have been irradiated with stripped ion beams of <tex-math>${}^{2}{\rm H},\ {}^{4}{\rm He},\ {}^{6}{\rm Li},\ {}^{7}{\rm Li},\ {}^{11}{\rm B},\ {}^{12}{\rm C},\ {}^{14}{\rm N},\ {}^{16}{\rm O},\ {}^{20}{\rm Ne}$</tex-math>, and <tex-math>${}^{40}{\rm Ar}$</tex-math>. The heavy ion linear accelerators at Berkeley and Yale have both been adapted to such studies, and the methods used in each of these laboratories are presented in this paper. In both cases scattering foils have been used to spread the beam to a useful size, and thin-walled ionization chambers have been used for the dosimetry. Precautions and corrections required for beam uniformity and accurate dose measurement have been established. One method allows the cells to be irradiated in a liquid environment, and the other in a gaseous environment. The ion velocity at the cells has in one case been identical for several different ions, and in other cases it has been different for each ion. The range of linear energy transfer represented by these ions extends from 65 to <tex-math>$19,500\ {\rm MeV}\text{-}{\rm cm}^{2}/{\rm gm}$</tex-math>. Some physical properties of accelerated <tex-math>${}^{40}{\rm Ar}$</tex-math> ions are described.