DETERMINATION OF IMPURITY RADIONUCLIDES IN 131Cs SOLUTIONS

The radiochemical purity of a 131 Cs solution used in brachytherapy is studied. After separating 131 Cs from the neutron irradiated targets BaO, Ba(NO 3 ) 2 , and BaCO 3 , the contribution of impurities was evaluated: 0.015% for 124 Sb and 0.012% for 132 Cs. The contribution of the parent 131 Ba to cesium solutions was, on average, 0.0067% for BaO, 0.01% for Ba(NO 3 ) 2 , and 0.011% for BaCO 3 . Brachytherapeutic treatment methods for cancer are widely used in nuclear medicine. The essence of brachytherapy lies in the fact that several tens of microsources of ionizing radiation are introduced into tissue tumors using special needles without any surgical intervention. The microsources are small titanium capsules‐grains containing a radionuclide which possesses definite nuclear characteristics, such as the presence of low-energy radiation for effective action on a tumor and absence of high-energy radiation to prevent damage to healthy tissue. Radiation sources based on 131 Cs were first used in 2004 in clinics in the USA and it was determined that 131 Cs suppresses the growth of cancer cells more quickly and effectively than 125 I and 103 Pd, which are used now [1, 2]. Radiation microsources based on 131 Cs have proven themselves well