**Part 1**

**Nuclear Physics** 

**1** 

*1Serbia* 

*2Bosnia and Herzegovina* 

**Air Kerma Rate Constants for Nuclides** 

It is often necessary to estimate the exposure rate at a distance from radionuclide emitting gamma or X rays. Such calculations may be required for planning radiation protection measures around radioactive sources, for calibration radiation monitoring instruments, for patient containing radionuclides or for estimating the absorbed dose to patients receiving brachytherapy. The factor relating activity and exposure rate has been various names: the k factor (Johns, 1961), the specific gamma ray constant (ICRU Rep. 10a, 1962), exposure rate constant (Parker et al., 1978) and gamma rate constant (Kereiakes & Rosenstein, 1980). Conversion to SI units required that this factor be replaced by the air kerma rate constant

> 2 *l*

where (dK air/dt) is the air kerma rate due to photons of energy >at a distance *l* from a point source of activity *A.* The SI unit for is J m2 kg-1 which, when the terms gray and

In the process of analysing accessible data on the are kerma rate constants and its precursos for many radionuclides often used in practice (Nachtigal, 1969; Ninkovic & Mladenovic, 1970; NCRP Rep. 49, 1976; Ungar & Trabey, 1982; Aird et al., 1984; Attix, 1986; Ninkovic, 1987; Wasserman & Groenwald, 1988; Ninkovic & Raicevic, 1992,1993; Sabol & Weng, 1995; Ninkovic et al., 2005) it was concluded that published data are in strong disagreement. That is the reason we decided to recalculate this quantities on the basis of the latest data on

gamma ray spectra and on the latest data for mass energy-transfer coefficients for air.

The kerma Kair , for interaction of X-rays and gamma rays with air is given by:

*A* ( *air dK*

**1. Introduction** 

which is now defined as:

=

becquirel are used, becoms Gy m2 s-1 Bq-1.

**2. Derivation of the equation for calculation of** 

**Important to Gamma Ray Dosimetry** 

**and Practical Application** 

Marko M. Ninkovic1 and Feriz Adrovic2 *1Institute of Nuclear Sciences – Vinca, Belgrade, 2University of Tuzla, Faculty of Science, Tuzla,* 

*dt* ) (1)
