Abstract

The statement considers various issues concerning the appropriate operational quantities for a conservative estimate of eye lens dose for penetrating radiation and low penetrating radiation. It also considers specific aspects of the dosimetric determination of eye lens dose, makes statements about suitable protection measures for the eye lens, and evaluates the data presented in SSK Volume 43 (1998, 2nd edition, 2006) on organ dose for the eye lens. To that end, the available scientific literature was analysed and comprehensive recalculations of the conversion coefficients for eye lens dose were carried out using a more realistic model of the human eye and the sensitive lens area as well as various dose equivalent quantities.

Based on the new data analysed in the scientific annex, the statement adopted includes the following elements:

• The data published in SSK Volume 43 on organ dose for the eye lens, and the conclusions drawn from these data, must be reviewed and supplemented to take account of new scientific knowledge.
• In photon radiation fields, the dose equivalent quantity H_p(0.07) adequately estimates eye lens dose at energies of < 200 keV; the same applies to H_p(10) at energies > 100 keV. In the specific case of exposure to X-rays for diagnostic purposes and exposure in scattered radiation fields, monitoring of dose equivalent quantity H_p(0.07) is sufficient to determine eye lens dose. Here, the personal dosimeter to be worn must either be calibrated on a rod phantom or, in the case of a partial-body dosimeter calibrated on a slab phantom. It must be ensured that the dosimeter also accurately measures backscattered radiation from the phantom. Ascertaining which of the dosimeters currently licensed for use already fulfil this second requirement is recommended.
• In beta radiation fields and for the sensitive region of the eye lens, the personal dose equivalent quantity H_p(3) estimates eye lens dose most accurately, although H_p(0,07) also provides a conservative value for eye lens dose for all radionuclides customarily used. However, for radionuclides with beta energies lower than around 1 MeV, a substantial overestimation of the eye lens dose occurs.
• Before introducing the dose equivalent quantity H_p(0.07) for photon radiation with dosimeters calibrated on the slab phantom and H_p(3) for electron radiation in order to determine eye lens dose, it is recommended that workplace observations (analysis of existing workplace dosimetric data / monitoring of workplace eye lens dose if no such data are available) be carried out in order to determine whether such introduction is appropriate.