Environmental Engineering Reference
In-Depth Information
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
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