The document describes the development of a new fibre optic dosimeter using fluoroperovskite materials. These materials were characterized through photoluminescence, optically stimulated luminescence, and radioluminescence studies. The dosimeter was tested at a linear accelerator and showed a linear response to radiation dose, demonstrating potential for radiation monitoring applications.

1. Development and characterisation of a
new fibre optic dosimeter
C. Gaedtke1, G. V. M. Williams1, S. G. Raymond2,
J. Donaldson3, L. Greig3, and J. Steel3
• Materials: fluoroperovskites
• Photoluminescence measurements
• Optically stimulated luminescence
• Radioluminescence studies
• Fibre optic dosimeter
• Characterization of dosimeter
1
SCPS, Victoria University, PO Box 600, Wellington 6140, New Zealand
2 IndustrialResearch Limited, PO Box 31310, Lower Hutt 5040, New Zealand
3 Blood and Cancer Centre, Wellington Hospital, Private Bag 7902, Wellington, New Zealand

2. Materials – Fluoroperovskites
• Motivation: Searching for new materials
that have good transparency, high
sensitivity, and with a response to
radiation that is comparable to that of
tissue.
• NaMgF3:Eu2+, NaMgF3:Mn2+,
Rb:MgF3:Eu2+, RbCdF3:Mn2+
Zeff = 7.6 for tissue
Zeff = 10.43 for 0.1 % Mn2+ in NaMgF3
Zeff = 12.33 for 0.05 % Eu2+ in NaMgF3
Zeff = 31.5 for 0.2 % Eu2+ in RbMgF3
Zeff characterizes a materials response to low
energy x-rays (α Z4/E3 for photoelectric effect)

3. Materials – Fluoroperovskites
• Transparent polycrystalline
samples are made by mixing
the starting materials in
stoichiometric ratio in a glassy
carbon crucible
• samples were heated slightly
above the melting
temperature and then slow
cooling down to below the
melting point
Orthorhombic fluoroperovskite structure

4. Optically stimulated luminescence (OSL) and
radioluminescence (RL) measurements
X-irradiation photostimulated luminescence
Irradiation, trapping and RL OSL emission
conduction band
F (A0)*
photo- (A0)*
electron stimulation
X-rays
hole
A + A0 A0
valence band

5. Photoluminescence measurements
NaMgF3:Eu2+
4f65d(Eg)
Wavenumber
6P
5/2
6P
7/2
8S
7/2
Q
PL excitation and emission from NaMgF3: 0.2% Eu2+ Eu2+ configurational coordinate diagram
bulk material in phosphorescence mode in NaMgF3:Eu2+

6. Photoluminescence measurements
RbMgF3:Eu2+
PL excitation and emission from RbMgF3: 0.2% Eu2+ in Eu2+ configurational coordinate diagram
phosphorescence mode in RbMgF3:Eu2+

7. Photoluminescence measurements
PL excitation and emission in phosphorescence mode
NaMgF3: 1% Mn
RbMgF3: 5% Mn
Energy levels of Mn2+ in a crystal field
10Dq

8. Optically stimulated luminescence
OSL measurements of Eu2+ doped samples in phosphorescence mode after 18 hours of
irradiation with the 241Am source
RbMgF3: 0.2% Eu2+ NaMgF3: 0.2% Eu2+

9. Optically stimulated luminescence
OSL measurements of Eu2+ doped samples in phosphorescence mode after 18 hours of
irradiation with the 241Am source
RbMgF3: 5% Mn NaMgF3: 1% Mn

10. Radioluminescence
RL measurements of Mn2+ doped bulk materials during irradiation with the 241Am source
RbMgF3: 0.2% Mn2+ NaMgF3: 1% Mn2+
irradiation overnight irradiation over the weekend

11. Radioluminescence
RL measurements of Eu2+ doped bulk materials during irradiation with the 241Am source
RbMgF3: 0.2% Eu2+ NaMgF3: 0.2% Eu2+
irradiation overnight irradiation over the weekend

12. Radioluminescence
RL measurements of Eu2+ doped nano particles (pressed into small pellets) during irradiation with
the 241Am source
NaMgF3: 1% Eu2+
irradiation over the weekend

13. Radioluminescence (RL) and optically stimulated
luminescence (OSL) measurments
• Real-time radiation dose and dose rate for radiation protection, non-destructive
testing, and in medicine for monitoring radiation dose during radiotherapy or for
dose verification and validation
• Advantages of OSL dosimeters:
• Retains dose information for a long
time
• Higher sensitivity than organic
scintillators
• Different shape of materials, can be
made as nano particles, bulk
transparent polycrystalline materials
or 2D sheets
• Can be nearly tissue equivalent
E.G. Yukihara and S.W.S. Mc Keever, „Optically stimulated luminescence (OSL) dosimetry in medicine“, Phys. Med. Biol., 53, R351, (2008)

14. Fibre optic dosimeter
We have a patent on Exposure to 10.5 µGy/s
the fluoroperovskite 241Am 60 keV γ-rays,
materials and a patent then OSL stimulated at
application on the 505 nm
device.

15. Characterization of the fiber optic dosimeter
• Different fluoroperovskite compounds have been attached to the end of
an optical fibre. Tested using the 241Am source at IRL and the linear
accelerator at Wellington hospital operating at 6MV
• Second set of measurements involved collaboration with the Wellington
Hospital medical physicists
• Can be used in different modes:
– Total dose readout: will reset the dosimeter
– Latest dose readout: when there is a series of irradiation, readout of each irradiation is
possible
– Pulsed dose rate monitoring: IR stimulated pulsed OSL
– Continual low dose rate monitoring: RL
– Continual high dose monitoring: RL and blue stimulation

16. Characterization of the fiber optic dosimeter
Setup at Wellington Hospital
Recent RL measurements at Wellington Hospital
showing the linear accelerator
with the bulk materials

17. Summary
• response to radiation that is comparable to that of tissue
• Fluoroperovskites show good PL, OSL and RL response and therefore used
in application
• Characterisation in Wellington Hospital showed that bulk materials have a
linear response to dose
• Further studies on nano particles as RL signal is dose independent
• Characterization of our fluoroperovskites at linear accelerator at
Wellington Hospital