Scintillation crystal, a radiation detection system including the scintillation crystal, and a method of using the radiation detection system
A scintillation crystal can include Ln (1-y) RE y X 3 , wherein Ln represents a rare earth element, RE represents a different rare earth element, y has a value in a range of 0 to 1, and X represents a halogen. In an embodiment, RE is Ce, and the scintillation crystal is doped with Sr, Ba, or a mixture thereof at a concentration of at least approximately 0.0002 wt. %. In another embodiment, the scintillation crystal can have unexpectedly improved linearity and unexpectedly improved energy resolution properties. In a further embodiment, a radiation detection system can include the scintillation crystal, a photosensor, and an electronics device. Such a radiation detection system can be useful in a variety of radiation imaging applications.
1. A scintillation crystal comprising La (1-y) RE y X 3 :Me 2+ , wherein:
RE represents a rare earth element other than La;
y has a value in a range of 0 to 1;
X represents a halogen; and
Me 2+ represents Sr, Ba, or any mixture thereof and has a concentration in a range of 0.0002 wt. % to 0.05 wt. %.
2. The scintillation crystal of claim 1 , wherein the scintillation crystal has a property including:
for a radiation energy range of 60 keV to 356 keV, the scintillation crystal has an average value for a departure from perfect linearity of no less than −0.35%;
for a radiation energy range of 2000 keV to 2600 keV, the scintillation crystal has an average value for a departure from perfect linearity of no greater than 0.07%;
for a radiation energy range of 60 keV to 356 keV, the scintillation crystal has an absolute value for a furthest departure from perfect linearity of no greater than 0.7%; or
any combination thereof.
3. The scintillation crystal of claim 2 , wherein the average value for the departure from perfect linearity (DFPL average ) is determined by:
DFPL
average
=
∫
E
lower
E
upper
DFPL
(
E
i
)
·
dE
i
E
upper
-
E
lower
,
where
DFPL(Ei) is DFPL at energy E i ;
E upper is the upper limit of the energy range; and
E lower is the lower limit of the energy range.
4. The scintillation crystal of claim 1 , wherein the concentration of Me 2+ is no greater than 0.03 wt. %.
5. The scintillation crystal of claim 1 , wherein the concentration of Me 2+ is in a range of 0.005 wt. % to 0.02 wt. %.
6. The scintillation crystal of claim 1 , wherein y has a value in a range of 0.001 to 0.5.
7. The scintillation crystal of claim 1 , wherein RE is Ce.
8. The scintillation crystal of claim 1 , wherein X is Br.
9. A radiation detection system comprising:
a scintillation crystal including La (1-y) RE y X 3 :Me 2+ , wherein:
RE represents a rare earth element other than La;
y has a value in a range of 0 to 1;
X represents a halogen; and
Me 2+ represents Sr, Ba, or any mixture thereof and has a concentration in a range of 0.0002 wt. % to 0.05 wt. %; and
a photosensor optically coupled to the scintillation crystal.
10. The radiation detection system of claim 9 , further comprising an electronics module coupled to the photosensor.
11. The radiation detection system of claim 10 , wherein the electronics module comprises an amplifier, a pre-amplifier, a discriminator, an analog-to-digital signal converter, a photon counter, another electronic component, or any combination thereof.
12. The radiation detection system of claim 9 , wherein the scintillation crystal has a property including:
for a radiation energy range of 60 keV to 356 keV, the scintillation crystal has an average value for a departure from perfect linearity of no less than −0.35%;
for a radiation energy range of 2000 keV to 2600 keV, the scintillation crystal has an average value for a departure from perfect linearity of no greater than 0.07%;
for a radiation energy range of 60 keV to 356 keV, the scintillation crystal has an absolute value for a furthest departure from perfect linearity of no greater than 0.7%; or
any combination thereof.
13. The radiation detection system of claim 12 , wherein the average value for the departure from perfect linearity (DFPL average ) is determined by:
DFPL
average
=
∫
E
lower
E
upper
DFPL
(
E
i
)
·
dE
i
E
upper
-
E
lower
,
where
DFPL(Ei) is DFPL at energy E i ;
E upper is the upper limit of the energy range; and
E lower is the lower limit of the energy range.
14. The radiation detection system of claim 9 , wherein RE is Ce, and X is Br.
15. A method comprising:
providing a radiation detection system including a scintillation crystal that includes La (1-y) RE y X 3 :Me 2+ , wherein:
RE represents a rare earth element other than La;
y has a value in a range of 0 to 1;
X represents a halogen; and
Me 2+ represents Sr, Ba, or any mixture thereof and has a concentration in a range of 0.0002 wt. % to 0.05 wt. %; and
exposing the scintillation crystal to a radioactive material; and
determine a performance characteristic at different energies.
16. The method of claim 15 , wherein determining the performance characteristic comprises determining a departure from perfect linearity for the scintillation crystal, wherein:
for a radiation energy range of 60 keV to 356 keV, an average value for the departure from perfect linearity of no less than −0.35%;
for a radiation energy range of 2000 keV to 2600 keV, an average value for the departure from perfect linearity of no greater than 0.07%;
for a radiation energy range of 60 keV to 356 keV, an absolute value for a furthest departure from perfect linearity of no greater than 0.7%; or
any combination thereof.
17. The method of claim 16 , determining the departure from perfect linearity is performed such the average value for the departure from perfect linearity (DFPL average ) is determined by:
DFPL
average
=
∫
E
lower
E
upper
DFPL
(
E
i
)
·
dE
i
E
upper
-
E
lower
,
where
DFPL(Ei) is DFPL at energy E i ;
E upper is the upper limit of the energy range; and
E lower is the lower limit of the energy range.
18. The method of claim 15 , determining the performance characteristic comprises determining an energy resolution for the scintillation crystal, wherein the energy resolution is no greater than approximately 6.40% at 122 keV, no greater than approximately 2.90% at 662 keV, no greater than approximately 1.90% at 2615 keV, or any combination thereof.
19. The method of claim 15 , providing the radiation detection system comprises providing the radiation detection system including the scintillation crystal, wherein RE is Ce, and X is Br.
20. The method of claim 19 , providing the radiation detection system comprises providing the radiation detection system including the scintillation crystal, wherein y has a value in a range of 0.001 to 0.2, and the concentration of Me 2+ is in a range of 0.005 wt. % to 0.02 wt. %.