The Food Irradiation (Scotland) Regulations 2009

PART 1 Dosimetry

Overall average absorbed dose

1.—(1) It can be assumed for the purpose of the determination of the wholesomeness of foodstuffs treated with an overall average dose of 10 kGy or less, that all radiation chemical effects in that particular dose range are proportional to that dose.

(2) The overall average dose, , is defined by the following integral over the total volume of the goods:

where	M	=	the total mass of the treated sample
	p	=	the local density at the point (x,y,z)
	d	=	the local absorbed dose at the point (x,y,z)
	dV	=	dx dy dz, the infinitesimal volume element which in real cases is represented by the volume fractions.

(3) The overall average absorbed dose can be determined directly for homogeneous products or for bulk goods of homogeneous apparent density by distributing an adequate number of dosimeters strategically and at random throughout the volume of the goods. From the dose distribution determined in this manner an average can be calculated which is the overall average absorbed dose.

(4) If the shape of the dose distribution curve throughout the product is well determined, the positions of minimum and maximum dose are known. Measurements of the distribution of dose in these two positions in a series of samples of the product can be used to give an estimate of the overall average dose.

(5) In some cases, the mean value of the average values of the minimum dose (min) and maximum dose (max) will be a good estimate of the overall average dose: i.e., in these cases: