Cobalt and cesium irradiators

Cobalt and cesium irradiators are among the irradiators used in radiotherapy and are a source of gamma radiation .

are sources of so-called telecuria-therapy, ie irradiation with radioisotope sources from a distance
An important parameter of radioisotope irradiators is the appropriate energy and physical half-life of radionuclides
today, however, they are used mainly in palliative and non-cancerous radiotherapy, they are gradually being decommissioned

Cobalt irradiators

The radiation source is radioactive cobalt ⁶⁰ Co (physical half-life is 5.29 years), which emits quantum gamma radiation with energies of 1.33 and 1.17 MeV with high penetration.

They are considered to be large irradiators (high source activity of at least 3,7,10 13 Bq) and are intended for deep radiotherapy.

Cesium irradiators

The radiation source is radioactive cesium ¹³⁷ Cs (physical half-life is 30.4 years), which emits a quantity of radiation with an energy of 0.66 MeV. It is used to irradiate pathological deposits to a depth of max. 5 cm.

Irradiation device

The irradiation device is called a cobalt cannon .

its essence is a strong lead protection box or spherical head (diameter up to 60 cm)
the head contains a core of tungsten alloy or uranium (they have higher absorption than lead)
the head transmits the primary gamma beam only in a narrow beam in the specified direction

Irradiation mechanism

the source remains at rest, the primary beam of gamma radiation is released by a movable screen located under the outlet channel of the cover
the source moves, rotates, or is pushed out of the center of the head above the output channel

Links

Resources

Šlampa, P .: Radiation Oncology. - textbook for students 5th year. LF MU Brno. < https://www.mou.cz/radiacni-onkologie-ucebni-text-pro-studenty-5-roc-lf-mu-brno/t2068 >

References

NAVRÁTIL, Leoš and Jozef ROSINA, et al. Medical biophysics. 1st edition. Prague: Grada, 2005. pp. 383-384. ISBN 80-247-1152-4 .