TANTALUM (Tantalum, That) — chemical element V of group of a periodic system of D. I. Mendeleyev, serial (atomic) number 73, at. the weight (weight) 180,95, valency is V; heavy refractory metal of gray color.
It is opened in 1802 by the Swedish chemist A. Ekeberg. In the nature is in a type of two isotopes: stable 181 That (99,99%) and radioactive 180 That (0,01%) with half-life of 1012. Average content of T. in crust 2,5*10 - 4 % on weight, in the hydrosphere and organisms the maintenance of T. it is not established. At usual conditions chemically maloaktiven, has good plasticity, durability, it is not toxic owing to what it is applied in surgery in the form of a wire to a fastening of bones, suture and a X-ray contrast tag in neurosurgery, etc.
For radiation therapy use 182 That, to-ry receive by radiation of a stable isotope 181 That thermal neutrons on reaction: 181 That + n -» 182 They are f at. This isotope breaks up with a departure of r-particles (the maximum energy 0,51 Mei) and emission of gamma quanta, energy to-rykh lies in the range of 0,22 — I, 24 Mei (apprx. 90% of gamma quanta has energy 1,12 — 1,24 Mei); turns into a stable isotope of tungsten. Half-life of 111 days.
Drugs with radioactive T. apply to an interstitial gamma therapy (see) in the form of pieces of a wire of various length with a diameter of 0,2 — 0,3 mm covered with a layer of gold or platinum for filtering of P-radiation; linear activity 1,2 — 2,4 mkyuri/cm (44,4 — 88,8 MBK/cm). Small pieces of a tantalic wire (2,5 — 3 mm) enter into nylon hollow threads (tubes) and use as flexible radioactive drugs (see). Drugs T. implement directly in fabric of a tumor and after implementation of a tumor of a dose of radiation, necessary for destruction — take. Drugs T., as well as other radioactive drugs, contain in special protective rooms (storages) from where in transport lead konteyne-rakh they are brought in radio handling; all manipulations with drugs T., implementation in a tumor and extraction is carried out by means of a set of special tools.
Bibliography: Pavlov A. S. Interstitial gamma and beta therapy of malignant tumors, M., 1967.
M. A. Fadeyeva.