Measurement of conversion coefficients beteen free-in-air kerma and personal dose equivalent for RQR spectra to be used in monitoring of the eye lens in nterventional radiology

Abstract In Report No. 90 of the International Commission on Radiation Units and Measurements (ICRU), new mass energy-absorption coefficients are listed which are based on renormalized Scofield photoeffect cross-sections. The mass energy-absorption coefficients are the basis for the conversion coefficients from air kerma to the operational quantities listed in ISO 4037-3. Although ICRU does not give a recommendation if these new mass energy-absorption coefficients should be applied instead of the values used so far, an examination of the possible consequences for radiation protection quantities is necessary. We calculated the conversion coefficients for the X-ray qualities specified in ISO 4037-1 with the new mass energy-absorption coefficients and with the mass energy-absorption coefficients used so far to determine the deviations. Our calculations show that the change of the conversion coefficients due to the new values from ICRU Report No. 90 is negligible.

Download Full-text

DEVELOPMENT OF A NEW SECONDARY STANDARD FOR H*(10)

Radiation Protection Dosimetry ◽

10.1093/rpd/ncz296 ◽

2020 ◽

Vol 188 (3) ◽

pp. 378-382

Author(s):

K Bairlein ◽

B Behnke ◽

O Hupe

Keyword(s):

Ionization Chamber ◽

Secondary Standard ◽

Dose Equivalent ◽

Air Kerma ◽

Radiation Fields ◽

Ambient Dose Equivalent ◽

Conversion Coefficients ◽

Aluminium Coating ◽

Pulsed Fields ◽

Ambient Dose

Abstract A secondary standard for ambient dose equivalent, H*(10), is necessary for the dissemination of the unit Sievert (Sv), but there is no such standard commercially available currently. Furthermore, the measurement of H*(10) instead of calculating H*(10) from air kerma and conversion coefficients is needed for unknown radiation fields. We developed a prototype of a new secondary standard for H*(10) based on a spherical 1 l ionization chamber for air kerma. This chamber was modified with copper wires at the inner surface to adjust the response of the chamber according to H*(10). Additionally, a Makrolon shell and an aluminium coating were added to optimize the response at energies below 50 keV. The prototype fulfils the requirements given in ISO 4037-2 in the energy range from 12 keV to 7 MeV. In combination with an electrometer, it can be used as area dosemeter, suitable for pulsed fields and for low energy radiation.

Download Full-text

CORRELATION OF EYE LENS DOSES AND PERSONAL DOSE EQUIVALENT MEASURED ON THE ARM OF INTERVENTIONAL CARDIOLOGISTS FOR A RETROSPECTIVE ASSESSMENT OF DOSES TO OPERATORS’ EYE LENS

Radiation Protection Dosimetry ◽

10.1093/rpd/ncaa039 ◽

2020 ◽

Vol 189 (3) ◽

pp. 271-278

Author(s):

Joanna Domienik-Andrzejewska ◽

Marcin Brodecki ◽

Marek Zmyślony

Keyword(s):

Threshold Dose ◽

Whole Body ◽

Eye Lens ◽

Dose Equivalent ◽

Retrospective Assessment ◽

Time Period ◽

Conversion Coefficients ◽

Left And Right ◽

Lens Opacities

Abstract Coefficients converting the readings of the whole body dosemeter worn on the left arm to eye lens doses were determined by analysing the correlations between Hp(10) and Hp(3) values. Doses were measured on a phantom for specific C-arm projections typically used during CA/PCI procedures. In order to estimate the cumulative eye lens doses, conversion coefficients were then applied to the dose records of interventional cardiologists collected in the database of dosimetry service between the years 1995 and 2009. The Hp(10) to Hp(3) conversion coefficients are 0.29 (CV = 34%) and 0.17 (CV = 42%) for left and right eye lens, respectively. However, they can vary from one laboratory to another depending on working technique. From among 61 interventional cardiologists, none exceeded the threshold dose of 0.5 Gy for eye lens opacities. However, 44% of interventional cardiologists were likely to exceed the annual limit of 20 mSv for the most exposed eye at least once in the analysed time period.

Download Full-text