Active Personal Eye Lens Dosimetry With the Hybrid Pixelated Dosepix Detector

Eye lens dosimetry has been an important field of research in the last decade. Dose measurements with a prototype of an active personal eye lens dosemeter based on the Dosepix detector are presented. The personal dose equivalent at 3 mm depth of soft tissue,
$\boldsymbol {H}_{\textbf {p}}\boldsymbol {(3)}$
, was measured in the center front of a water-filled cylinder phantom with a height and diameter of 20 cm. The energy dependence of the normalized response is investigated for mean photon energies between 12.4 and 248keV for continuous reference radiation fields (N-series) according to ISO 4037. The response normalized to N-
$60\,\,({\overline{E}=47.9\,\text {keV}})$
at
$\boldsymbol {0^{\circ }}$
angle of irradiation stays within the approval limits of IEC 61526 for angles of incidence between
$\boldsymbol {-75^{\circ }}$
and
$\boldsymbol {+75^{\circ }}$
. Performance in pulsed photon fields was tested for varying dose rates from
$\boldsymbol {0.1(\,{\textbf {Sv}}/{\textbf {h}})}$
up to
$\boldsymbol {1000}\,({\textbf {Sv}}/{\textbf {h}})$
and pulse durations from
$\boldsymbol {1\,\textbf {ms}}$
up to
$\boldsymbol {10\,\textbf {s}}$
. The dose measurement works well within the approval limits (acc. to IEC 61526) up to
$\boldsymbol {1\,({\textbf {Sv}}/{\textbf {h}}})$
. No significant influence of the pulse duration on the measured dose is found. Reproducibility measurements yield a coefficient of variation which does not exceed
$\boldsymbol {1\%}$
for two tested eye lens dosemeter prototypes.