Light Collection Enhancement Analysis for Digital X-Ray Detector Using Gd2O2S:Tb and CsI:Tl Phosphors in Nanoscale Treatment - Atomic Nanoscale Technology in the Nuclear Industry - page 72

6.3 Results
In. the. coniguration. of. the. system,. the. microlens. diameter. is. 23. µm.. The.
distance. between. a. screen. and. the. microlens. is. 50. µm.. These. are. several.
thousands.of.nanometers..The.light.collection.eficiency.is.shown.as.the.per-
centage.of.the.light.collected.in.the.photodetector..Each.point P .stands.for.the.
pixel.point.of.the.photodetector..The. P9 .is.the.center.pixel.and.there.are.pix-
els.from. P1 .to. P8 .around. P9 ..Table 6.3.shows.each.geometrical.simulation.in.
the.Lambertian.and.isotropic.source.assumptions,.where.the.light.collection.
eficiencies. for. Gd 2 O 2 S. and. CsI. are. shown.. The. 27-kVp. and. 82-µm. Gd 2 O 2 S.
case. shows. the. highest. light. collection. in. both. Lambertian. and. isotropic.
geometries..In.the.case.of.CsI,.the.20-keV.and.150-µm.case.has.the.highest.
light.collection.eficiency..The.energy.range.is.usually.between.17.kVp.and.25.
kVp.in.clinical.situations..It.is.reasonable.that.in.this.step.of.the.experiment.
the.highest.eficiency.can.be.standard.data.by.comparisons.among.data.

TABLE 6.3
Light.Collection.Eficiency.(%)

LambertianSource(%)

L1 L2

Energy
(kVp)

Thickness
(µm;mg/cm 2 ) P9 P1-P8 P6-P9 P1-P5

(a)Gd 2 O 2 S:Tb
. 25
. 26
. 27

48;.35
46;.34
46;.34
82;.60

32.03
14.43
17.07
76.00

0.094
0.042
0.049
0.220

0.013
0.209
0.174
0.210

0.002
0.030
0.025
0.020

. 28
. 30
. 90

40;.29
44;.32
68;.50
68;.50

18.41
33.50
18.46
18.07

0.053
0.097
0.053
0.052

0.153
0.001
0.152
0.158

0.022
0.000
0.022
0.023

109;.80 13.36 0.039 0.220 0.031

(b)CsI:Tl
. 20 a
. 35 a
. 50 a
. 30

150;.68
150;.68
150;.68
150;.68

76.00
67.52
73.58
59.25

0.220
0.195
0.213
0.171

0.210
0.419
0.259
0.749

0.030
0.060
0.037
0.107

200 147;.47

. 299;.135

59.23
50.17

0.171
0.145

0.740
1.2111

0.106
0.173