ANALITYCAL CALCULATION OF FWHM
AND COMPARISON WITH EXPERIMENTAL DATA
Copyright
©
2013
Diego Cecchin - Davide Poggiali - Stefano De Marchi - Franco Bui
University Hospital of Padua - Nuclear Medicine Service
(
Dir. Prof. Franco Bui
)
Via Giustiniani 2 - 35128 - Padova - Italy
DATA (PROVIDED BY VENDOR) FOR ANALITYCAL CALCULATION
L =
Hole lenght (mm)
c =
Crystal Thickness (mm)
D =
Hole size (mm)
From:
To:
x =
Source-Collimator distance (mm)
[step
(mm)]
μ
= linear att. coeff. of the coll. material at used energy
For a Lead Collimator (density ρ= 11.34 g/cm
3
)
At 150 KeV μ=1.910 cm
2
/g * 11.34 g/cm
3
=21.6594 cm
-1
= 2.16594 mm
-1
At 200 KeV μ=0.936 cm
2
/g * 11.34 g/cm
3
=10.61424 cm
-1
= 1.061424 mm
-1
At 300 KeV μ=0.373 cm
2
/g * 11.34 g/cm
3
=4.22982 cm
-1
= 0.422982 mm
-1
At 400 KeV μ=0.215 cm
2
/g * 11.34 g/cm
3
=2.4381 cm
-1
= 0.24381 mm
-1
At 500 KeV μ=0.150 cm
2
/g * 11.34 g/cm
3
=1.701 cm
-1
= 0.1701 mm
-1
t =
Septa Thickness (mm)
K =
Constant (0.26 for hexagonal holes; 0.28 for squared holes)
R
int
=
Intrinsic Spatial Resolution (mm)
R
coll
= D(L
corr
+x+c)/L
corr
R
syst
= √(R
coll
2
+ R
int
2
) = FWHM
L
corr
= L-2μ
-1
Max. septal penetration (%) = exp(-μ*w)*100
where w=(Lt)/(2D+t)
Collimator efficiency (in air) g = K
2
(D/L
corr
)
2
[D
2
/(D+t)
2
]
DOWNLOAD Matlab/Octave code for FWHM calculation on static DICOM images
EXPERIMENTAL DATA
(if you want omit these values)
X = EXPERIMENTAL DATA (mm) : Source-Collimator distance
Y = EXPERIMENTAL DATA (mm) : FWHM
SD = EXPERIMENTAL DATA (mm) : Standard deviation of FWHM
Show Analitical Data Labels:
Show experimental Data Labels:
CALCULATE