Physics Laboratory
UNITED STATES DEPARTMENT OF COMMERCE
National Institute of Standards and Technology
Gaithersburg, MD 20899-0001
Radiochromic Film
Christopher G
G. Soares
Ionizing Radiation Division
National Institute of Standards and Technology
Acknowledgements
Book chapter co-authors, whose material and ideas I liberally borrowed:
Samuel Trichter
New York – Presbyterian Hospital
Weill Cornell Medical Center
N Y
New
York,
k NY 10021
sat9014@nyp.org
and
Dr. Slobodan Devic
McGill University
SMBD Jewish General Hospital
Montréal,
Montréal Québec H3T 1E2
slobodan.devic@ mcgill.ca
Acknowledgements
Dr. David Lewis
International Specialty Products (ISP), Wayne. NJ
supplying the dosimeter material used and the long years of friendship
Marcie Lombardi, Elizabeth Meek and Jason Walia
Georgetown University, Washington, DC
assistance
it
with
ith MD-55-2,
MD 55 2 EBT andd EBT-1
EBT 1 film
fil irradiations
i di ti
andd readouts
d t
at NIST
Scott Robertson
University of Maryland, College Park, MD
assistance with filter
filter, EBT2 and EBT2-1
EBT2 1 film irradiations and readouts
at NIST
Drs. R
D
Ronaldo
ld Mi
Minniti
iti and
d Guerda
G d Massillon
M ill
NIST, Gaithersburg, MD
assistance with 60Co irradiations of films at NIST
Absorbed Doses in Typical Medical Procedures and
Ranges of Passive Detectors
Photographic Film
Optically Stimulated Luminescence
Thermoluminescence Dosimetry
Gel Dosimetry
Alanine
Fricke Dosimeter
Radiochromic Films
Diagnostic
Diagnostic
0.01
0.1
External Beam
1
Brachytherapy
Brachytherapy
10
Absorbed Dose, Gy
100
1000
Pioneers
• William McLaughlin,
McLaughlin NIST
– From 1965 to 2005
Organic free
free-radical
radical imaging medium can
combine photopolymerization with leuco dyes
that p
produce color upon
p irradiation.
• David Lewis, International Specialty Products (ISP)
– Since 1980s:
Radiochromic films based on polydiacetylene
have been introduced for medical applications
pp
Radiochromic Films
Radiochromic film consists of a single
or double layer of radiation-sensitive
organic microcrystal monomers,
monomers on a
thin polyester base with a transparent
coating
Radiochromic Films (Cont.)
Color of the radiochromic films turns to a shade
of blue upon irradiation.
D k
Darkness
off th
the fil
film iincreases with
ith iincreasing
i
absorbed dose.
No processing is required to develop or fix the
image.
g
Sample Application:
IMRT QA
Measuring Transmission & Optical Density
Light
g
Source
Detector
II
0
Densitometer
Transmission 
I
I0
I 
OD  log 0 
 I 
Absorbance Scans of EBT Film Irradiated with 60Co
4
3.5
Optical D
Density, AU
3
2.5
2
1.5
1
0.5
0
400
450
500
550
600
Wavelength, nm
650
700
750
0 Gy
0.1 Gy
0.15 Gy
y
0.2 Gy
0.3 Gy
0.5 Gy
0.7 Gy
y
1 Gy
1.5 Gy
2 Gy
3 Gy
5 Gy
7 Gy
10 Gy
633 nm
Older Radiochromic Film Types
• GAFCHROMIC HD-810 (Formerly: DM-1260)
– 20 cm x 25 cm x 0. 1 mm
– Nominal dose range: 10-1000 Gy
– Approximate
A
i
sensitivity:
i i i 3 mAU/Gy
AU/G
• GAFCHROMIC MD-55-1 (no longer available)
– 12.5 cm x 12.5 cm x 0.08 mm
– Nominal dose range: 2-200 Gy
– Approximate sensitivity: 10 mAU/Gy
Adhesive
• GAFCHROMIC MD-55-2 (aka NMD-55)
~20 m
– 12.5 cm x 12.5 cm x 0.23 mm
~20 m
– Nominal dose range: 1-100 Gy
– Approximate
A
i t sensitivity:
iti it 20 mAU/Gy
AU/G
• GAFCHROMIC HS (no longer available)
– 12.5 cm x 12.5 cm x 0.23 mm
– Nominal dose range: 0.5-50 Gy
– Approximate sensitivity: 35 mAU/Gy
Emulsion
6.5 m
97 m
P l
Polyester
16 m
67 m
67 m
16 m
25 m
16 m
67 m
97 m
38m
100 m
XR Radiochromic Film Types
• GAFCHROMIC XR-T (no longer available)
XR-T Emulsion
– 12.5. cm x 12.5 cm x 0.21 mm
– Nominal dose range: 0.01-5 Gy
97 m
18 m
97 m
Transparent Yellow Polyester
• GAFCHROMIC RTQA
– 36 cm x 43 cm x 0.23 mm
– Nominal dose range: 0.01-5 Gy
Adhesive
12 m
RTQA
Q Emulsion
97 m
17 
m
97 m
surface
layer
3 m
Opaque White Polyester
• GAFCHROMIC XR-RV2
– 36 cm x 43 cm x 0. 23 mm
– Nominal dose range: 0.01-5 Gy
Adhesivee
Adhesi
12 m
XRQA Emulsion
• GAFCHROMIC XR-QA
XRQA Emulsion
– 36 cm x 43 cm x 0.26 mm
– Nominal dose range: 0.001-0.2 Gy
97 m
17 m
97 m
97 m
25 m
25 m
97 m
3 m
10 m
EBT Radiochromic Film Types
surface
97 m
• GAFCHROMIC EBT (no longer available)
l
layer
25 m
EBT Emulsion
3 m
– 20 cm x 25 cm* x 0.23 mm
25 m
97 m
– Nominal dose range: 0.05-100 Gy
Cl Polyester
Clear
P l t
– Approximate
A
i
sensitivity:
i i i 400-800
400 800 mAU/Gy
AU/G
97 m
• GAFCHROMIC “EBT-1” (no longer available)
3 m
EBT Emulsion
25
m
– 36 cm x 43 cm x 0.12 mm
97 m
– Nominal dose range: 0.1-200 Gy
– Approximate sensitivity: 200-400 mAU/Gy
• GAFCHROMIC EBT2
Adhesi e
Adhesive
50 m
25 m
5 m
– 20 cm x 25 cm* x 0. 29 mm
EBT2 Emulsion
30 m
– Nominal dose range:
175 m
– Approximate
A
i t sensitivity:
iti it
• GAFCHROMIC “EBT2-1” (by request only)
EBT2 Emulsion
30 m
– 20 cm x 25 cm x 0.20 mm
175 m
– Nominal dose range:
– Approximate sensitivity:
*typical size; 36 cm x 43 cm available
EBT vs Older Emulsion
400
450
500
550
600
650
700
750
1.4
1.4
GAFCHROMIC EBT emulsion 1.5 Gy
1.2
1.2
optical d
density / AU
U
GAFCHROMIC emulsion (MD-55-2) 15 Gy
1
1.0
0.8
0.8
0.6
0.6
0.4
0.4
0.2
0.2
0.0
400
450
500
550
600
wavelength / nm
650
700
0
750
Some Film Handling Tips
• try to controll temperatures during
d i irradiation,
i di i
storage & readout in a consistent fashion
• handle films with care, avoiding dust, fingerprints
or over bending
• store film in dry, dark environment
• avoid prolonged exposure to UV light
• cut sandwich films with scissors, punches or paper
cutters
• wait a few days after cutting before irradiating
• at temps above 70 C dye is deactivated
More Tips
• write ID numbers on films in reproducible manner
to indicate emulsion-coated side and direction
• HD-810 emulsion side easily determined by
wetting a corner – turns cloudy temporarily
• MD-55-2 compressible – take care measuring
thickness if it matters in an application
• use histogram (frequency) analysis for uniform
films
fil
• consider rolling film for equatorial measurements
• irradiate at slant incidence for single shot DDs
Dose Response for Older Emulsion
• film is insensitive to light at  > 300 nm
– But
B sensitive
i i to UV at lower
l

• films should be stored in the dark, at temp <
25ºC and relative humidity < 50% to optimize
the useful life of the film
• dependence of the absorption spectrum with
dose has been documented
• difference between fractionated and
unfractionated response is ~ 1%
Summary of Recommended Procedures:
Fil Use
Film
U
• note model and lot numbers
• note film orientation and allignment
• control time between irradiation & readout (at
least 24 h) or use film annealing
• check film uniformity
• for non-sandwich films in non-penetrating
radiation applications, note emulsion side
(check by wetting corner)
Calibration & Sensitivity
• Calibration:
- irradiation of samples to known absorbed dose levels
• Calibration curve:
– Relation between dose and response
• Sensitivity:
– Average change in response per unit dose
• calculate over most linear portion of the calibration curve
– Depends on:  used for readout, scanner, film batch,
beam quality, readout time, temperatures, humidity,
...
Radiochromic Film Calibration Fields
contact irradiations with calibrated 90Sr/Y
planar applicator, or
irradiations with 60Co beams of known
absorbed-dose rate, or
irradiations with photon or electron linac beams
of known absorbed-dose rate
large well-characterized uniform radiation field
HD--810 Calibration Exposures w/ 90Sr Eye Plaque
HD
numbers are irradiation times in seconds at a dose rate of about 0.5 Gy/s
EBT2 Calibration Exposures w/ 60Co in Water
Linearity of Dose Response is Instrument Dependent
0
2
4
6
8
10
12
3.5
3.5
Instrument dependent
linearity for EBT film
optical density / A
AU
30
3.0
30
3.0
2.5
2.5
2.0
2.0
1.5
1.5
laser scanning densitometer
1.0
1.0
spectrophotometer
0.5
0.5
0.0
0.0
0
2
4
6
absorbed dose / Gy
8
10
12
Calibration Phantoms and Mounting Jigs
• Sandwich films can be irradiated directly in
water and held at depth in appropriately
d i d jigs
designed
ji
• Uncoated films can be sealed in waterproof
pouches (e.g., Food Saver bags) and held in
similar jigs
Plastic Calibration Phantoms
•
•
•
•
The usuall cast off water-equivalent
Th
i l plastic
l i characters
h
can be
b
used in lieu of in-water irradiations, such as
polystyrene:
l t
best
b t for
f beta
b t particles,
ti l but
b t also
l usedd for
f highhi h
energy beams
Solid WaterTM (WT1): standard for photon brachytherapy
other water equivalent plastics (e.g. Plastic Water, Virtual
Water etc.)
Water,
etc )
A150 plastic: for high rate charged particle irradiations
(conducting)
Note: in all phantom designs avoid air gaps to prevent
electron streaming losses
Summary of Recommended Procedures:
C lib ti
Calibration
• use a large well-characterized field, ideally
of the same q
qualityy as unknown field
• otherwise, any known dose rate field
• obtain response vs.
vs dose over range of
interest (extrapolation is dangerous)
• sandwich
d i h films
fil can be
b irradiated
i di d
unprotected in water but avoid prolonged
i
immersions
i
Corrections: Intrinsic Linearity, kl(Mdet(D))
Calibration Curve for MDMD-5555-2 film with 60Co
0
50
100
150
2.0
18
1.8
net optical density / A
AU
18
1.8
Sensitivity =
21.5 mAU/Gy
1.6
200
2
1.6
14
1.4
14
1.4
1.2
1.2
1.0
1
0.8
0.8
this is the inverse
of the sensitivity
0.6
0.6
D (Gy) = (0.335 + 46.5 NOD) / (1 - 0.0215 NOD – 0.167 NOD2)
this term is the intrinsic linearity
kl(Mdet(D))
0.4
0.2
0.0
0
50
100
absorbed dose / Gy
150
0.4
0.2
0
200
C i
Calibration
i Curve
C
for
f MDMD-5555-2 film
fi with
i 60Co:
C
Sensitivity Curve
Net Optical Density per Un
nit Absorbed Do
ose, mAU/Gy
25
20
15
10
5
0
1
10
100
Absorbed dose, Gy
1000
Calibration Curve for EBT film with 60Co
read in the red channel of a p
photo scanner
trans
smission
0.01
60000
0.1
1
10
60000
50000
50000
40000
40000
30000
30000
20000
20000
10000
10000
0
0.01
0
0.1
1
absorbed dose / Gy
10
Calibration Curve for EBT film with 60Co
read in the corrected red channel of a photo scanner
0
2
4
6
corrrected net o
optical dens
sity / AU
3.0
8
10
3
Sensitivity =
364 mAU/Gy
2.5
2.5
20
2.0
2
1.5
1.5
1.0
1
0.5
0.0
0
this is the inverse
of the sensitivity
0.5
D (Gy) = (-0.0263 + 2.75 NOD) / (1 - 0.0535 NOD – 0.00555 NOD2)
this term is the intrinsic linearity
kl(Mdet
d t(D))
0
2
4
6
8
10
absorbed dose / Gy
Calibration Curve for EBT film with 60Co
sensitivityy curve for corrected red channel of p
photo scanner
net optical density pe
er unit abso
orbed dose /
mAU/Gy
0.01
600
0.1
1
10
600
550
500
500
450
assumed linearity
400
350
400
fitted linearity
300
300
250
200
0.01
200
0.1
1
absorbed dose / Gy
10
.
Corrections: DoseDose-Rate Dependence, kdr(D)
Usually taken as unity, although
• Saylor
y et al showed that for MD-55-1:
– There is no dose rate response within an
uncertaintyy of ~ 5% (( one SD))
• McLaughlin et al studied MD-55-2 for:
– Dose = 20,
20 40,
40 60 Gy
– Dose rate = 0.08 to 80 Gy/min
– No dose rate response within an uncertainty
of ~ 5% ( one SD)
– But at 60 Gy there is ~ 10% higher response
at lower dose rate
Corrections: Intrinsic Energy Dependence, kbq(Q)
taken as a constant independent of
energy since the energy necessary to
polymerize the diacetylene molecule is
small (< 1 eV)
Corrections: AbsorbedAbsorbed-Dose Energy Dependence, f(Q)
calculations for this textbook
GAFCHROMIC E
Emulsions
li
Ch
Characteristics
t i ti
• Effective Z: 6.0 - 6.5
• Sensor material has similar electron
stopping power as water & muscle
• Sensor material has similar mass-energy
absorption
b
ti coefficients
ffi i t as water
t and
d
muscle for h > 100 keV
• For secondary electron 0.1 to 1.0 MeV
and h 0.1 to 1.33 MeV : ~2% of water
and muscle
Corrections: NonNon-Uniformity of Response, knu(x,y
x,y))
• Non-uniformity due to local fluctuations (spikes):
– Small scale: film grain size,
size spatial and signal
resolution of scanner, pixel size, electronic noise, …
– Relative response is compared with the mean
response in the ROI
• Non-uniformity due to regional variations:
–L
Large scale:
l non-uniformity
if
it in
i film
fil emulsion
li
layer(s), systematic scanner problem(s)
– Difference (or ratios) of max-min
max min response in ROI
Non--U
Non
No
Uniformity
o
y (Cont.)
(Co .)
• Acceptable tolerances for film uniformity
vary with
i h the
h application
li i
• Regional variations for MD-55-1 & MD-552 along two central orthogonal directions:
– Longitudinal ( to coating application): ~ 4%
– Transverse ( to coating application): ~ 15%
• Local fluctuations for MD-55-2:
– Dose > 20 Gy: ~ ± 3%
– Dose < 10 Gy:
y ~ ± 5%
%
D bl E
Double
Exposure Technique
T h i
A technique has been suggested using a
matrix of correction factors to be applied
pp
to
an irradiated film (2) from the readings of a
uniformly
y irradiated film (1):
( )
ODnet( i,j)
i j) = [OD2(i,j)
(i j) - OD1(i,j)]
(i j)] / f(i,j)
f(i j)
f(i,j) = OD1(i,j) / <OD1(i,j)>
Problems with the Double Exposure Technique
• Requires second exposure, readout, doubling work
• Requires exact image registration for the two
images (This often requires both translational and
rotational transformations of one relative to the
other))
• Only works if film uniformity is worse than
statistical
i i l pixel-to-pixel
i l
i l fluctuations
fl
i
since
i
these
h
are
compounded in taking of ratios
Simplified Double Exposure Technique
Rather than registering
g
g the images,
g , jjust use the
average density for the correction
Caveat: only works for small film samples (1cm2
or less) since uniformity variations are on this
scale
Something Brand
Brand--New for Non
Non--Uniformity Corrections
The newest versions of EBT2 contain a yellow marker dye in the
emulsion which gives a strong absorbance in the blue portion of the
spectrum. In principle this signal is proportional to emulsion
thickness and can be used to calculate knu(x,y
x,y).
,y))).
,y
Corrections: Unirradiated Film Reading, Mdet(0)
• Necessary to obtain net optical density
• Important as check on film quality
Corrections: Readout NonNon-Uniformity, kpos(x,y
x,y))
• if using small films, avoid this effect by
always
y reading
g films in the same area of the
densitometer or scanner
• for large films,
films can be quantified by using
uniformly irradiated, large area reference
films that have been checked for uniformity
by independent methods
Corrections: Time and Temperature Effects, ktT(T,t,D
T,t,D))
• Unlike TLDs, signal grows with time with RCF
• Growth is logarithmic with time
• During the 1st 24 hrs after irradiation,
absorption increases by up to 16%.
– 4% thereafter for up to 2 wks
• Greatest increase in absorption occurs at
higher temp: ~ 40
40ºC
C
• Best approach is to control the times and
t
temperatures
t
and
dk
keep constant
t t & uniform
if
Rapid Color Stabilization for Older
GAFCHROMIC Film Models
Reinstein
R
i t i ett al.
l suggestt annealing
li att 45 C
for 2 hours, which is the equivalent of storing
att room temperature
t
t
for
f months
th (for
(f those
th
too impatient to wait a few days)
Note: this has not been verified for EBT
models
d l
Environmental Factors
• Humidity (HD-810) effect for 6 to 94% < ± 2%
p
effect ((MD-55-1 & MD-55-2)) for
• Temperature
10 to 50C:
– Response varies with dose as well as  of analysis
– At ~ 50
50C
C there is an erratic variation in response
– At > 60C the blue dye changes to red and may cause
significant change in sensitivity
• UV exposure with  > 300 nm(sunlight or
continuous white fluorescent lights) colors the film
– Needs
N d tto b
be stored
t d iin opaque container
t i
• Shipping and handling may cause damaged locations
– Color of the film turns from clear to milky white
– Need to be read no closet than ~ 1.5 mm away from cut edge
Overall Conversion of Reading to
Dose to Medium,
Medium Dmed(Q)
Example of Uncertainty Budget for Measurement of a LowLowEnergy Photon Brachytherapy Source at 1 cm in Water with
GAFCHROMIC Emulsion Calibrated with 60Co Gamma Rays
Film Measurement Methods
”Very Old School”: White Light Densitometers
apertures should be 1 mm or less
if manual, positional reproducibility may be difficult
67 
“Old School” High Resolution Scanning Densitometers
((laser densitometers))
((camera based systems)
y
)
point by point 2-D scanning
633 nm laser (HeNe)
100-m diameter spot size
40- m minimum step size
CCD imaging system
660 nm light bed (LEDs)
228 x 358 pixel array
<10µm minimum pixel size
“Wave of the Future”: Color Photo Scanners
inexpensive, buts use white light sources (UV concerns)
48-bit image depth recommended
have to learn to deal with transmission values & TIFF
up to
t 2400 d
dpii => 10 μm pixels
i l possible
ibl
three color channels (RGB) available: new horizons!
Densitometer Parameters
• light source
• spatial resolution
• light
g detection
• p
positional accuracyy
• response linearity
• bed geometry
• response accuracy
• acquisition time
• response
reproducibility
• control software
• environmental factors
• response stability
Types of Densitometers
•
•
•
•
Moving:
single light source
single detector
sample and/or light source
source-detector
detector moved
•
•
•
•
Imaging:
uniform backlit bed
imaging device
no movement
• Hybrids:
• combination of the above
Example of a
Moving System
Example
of an
Imaging
System
Light Sources
•
•
•
•
•
•
•
wavelength
• Examples:
• HeNe laser, 633 nm, nearly 0 FWHM
FWHM
1 mW,
mW 50μm
50 m diameter spot
intensity
• Filtered white light
• LED light bed
size
uniformity
match to light detector
match to film being
read
Other Examples of Red Light Sources compared to
GAFCHROMIC HS Absorbance Spectrum
Red Channel
Green Channel
Light
g Detectors
sensitivity
Types:
spectral efficiency
PMT
linearity
signal resolution
CCD: (linear
array most
common now))
Signal Resolution
The maximum number of “shades of g
grey”
y a
pixel value may contain, expressed as a power of
p
of 28=256
2. Thus an “8-bit” scanner is capable
shades of coloration distinction, while a “16-bit”
p
of 216=65536.
scanner is capable
Spatial Resolution
M i S
Moving
Systems:
I
Imaging
i S
Systems:
light source size
pixel size
space between readings
dead area
Both:
light diffusion in sample
stray light
Positional Accuracyy
Moving Systems:
stepping accuracy
bi directional motion
bi-directional
Imaging Systems:
regularity of imaging grid
Dimensional Accuracy
A problem
with
stepping
Reader Bed Parameters
Moving Systems:
Imaging Systems:
maximum pixel size
light source uniformity
transmission uniformity
Both:
fil positioning
film
iti i
size
Moiréé Patterns in Laser Densitometer with EBT Film (D=7 Gy)
Moir
Clear gglass
Frosted gglass
Eff off Polarized
Effect
P l i d Light
Li h
• Klassen et al studied polarity effect for
MD-55-2:
– Microcrystals in sensitive layers have a
preferred orientation (i.e. elongated)
– Monomers
M
in
i microcrystals
i
l have
h
a preferred
f
d
orientation in the same plane of the film
– OD would vary with the plane of
polarization of the analyzing light and would
change with film orientation
Polarization Effects in EBT Films
The new films
Th
fil exhibits
hibit fil
film-orientation
i t ti
dependent polarization effects. These are
severe when usingg lasers for readout:
– Microcrystals in sensitive layers have a
preferred orientation (i.e. elongated)
– Monomers in microcrystals have a preferred
orientation in the same plane of the film
– OD
OD varies
i as the
th plane
l
off polarization
l i ti off
the analyzing light changes with film
orientation
Solutions:
– maintain rigorous
g
film mountingg convention
and keep consistent with calibration
– use a diffusing layer during readout
Manufacturer Recommendations
f EBT Fil
for
Film Scanning
S
i Orientation
O i t ti
Coating Direction
Scanning Direction
Effect of EBTEBT-1 Film Orientation During Readout
net optical density / m
mAU
0
1
2
3
4
5
6
7
8
9
10
1800
1800
1600
1600
1400
1400
1200
1200
1000
1000
800
800
600
600
laser scanner perpendicular
red channel photo scanner perpendicular
red channel photo scanner parallel
laser scanner p
parallel
400
200
400
200
0
0
0
2
4
6
absorbed dose / Gy
8
10
Response Linearity
calibration
lib ti curve using
i fil
film
calibrated neutral density filters
comparison with spectrophotometer
Spectrophotometer vs.
S
Scanning
i Densitometer
D it
t
Calibration using Neutral Density Filters
ra
aw densitom
meter readiing / NOD
3.0
laser densitometer correction factor=1.08
photo scanner red channel
' ' =2.21
photo scanner green channel ' ' =2.63
photo
h
scanner bl
blue channel
h
l ' ' =2.82
2 82
Series5
25
2.5
2.0
1.5
1.0
0.5
00
0.0
0.0
0.5
1.0
1.5
2.0
spectrophotometer reading / AU
2.5
3.0
Response Reproducibility:
HD--810 Film in a Laser Scanner
HD
Relativ
ve Standard
d Deviation for Unifor
Another Laser Densitometer Characteristic Curve
D t
Determined
i d with
ith Old and
d New
N E
Emulsion
l i Films
Fil
16%
MD-55-2 film
MD-55-2
14%
12%
EBT film
IMRT film
10%
MD-55-2chop
8%
6%
4%
2%
0%
0
500
1000
1500
Optical Density, mAU
2000
2500
Daily Reader Quality Control
• Scan of bare reader bed
• Scans of stable reference artifacts (neutral
density filters are best for this)
Scanning Densitometer Control Graph
Net Reading of the Reference Filter
Environmental Factors
temperature during readout
setup/interior lighting
Data Acquisition
q
Time
Moving Systems:
time to step
p between p
positions
Both:
time to make measurement
data transfer time to host computer
Software
flexibility
access to data
color images
iso density contour plots
iso-density
conversion
i tto dose
d
via
i stored
t d calibration
lib ti
Special Considerations for Document Scanners
Pixel depth – should be at least 12 bits/color
(make sure all color compensation & image
adjustments are turned off)
Spatial resolution – should capable of at least
300 dpi (maximum that should be needed)
Data format – learn to deal with TIFFs
System linearity – check with neutral density
filters; I am surprised at how good ours is
Dealing with Tagged Image File Format (TIFF)
Freeware is available, e.g., ImageJ
see http://rsb.info.nih.gov/ij/
http://rsb info nih gov/ij/
If you prefer to “roll
roll your own
own”, get hold of a TIFF tag
viewer to see how the header is constructed and where
things are; see,
see e.g.,
eg
http://www.awaresystems.be/imaging/tiff/astifftagviewer.html
Remember to use “uncompressed” format
Summary of Recommended Procedures:
R d
Readers
• select densitometer with sufficient signal
g
resolution
• determine maximum measurable OD
• measure OD at red wavelengths for
maximum sensitivity
• use green & blue channels to extend dose
measurementt range
• monitor absorbance scale stability with
neutral density filter readings
Some Medical Applications of
Radiochromic Film Dosimetry
• Hot particle dose averaging
• Beta
Beta--ray ophthalmic applicator calibration
• Interface effects
• Stereotactic radiosurgery
• Intravascular brachytherapy
• Beam
B
penumbra
b measurements
t
• Proton beam depth dose
• Radium applicator retrospective studies
• QA of IMRT beams
• Linac and HDR commissioning and QA
• and many more …
Conclusions
• There has never been a more exciting time
to be working with radiochromic film
dosimetry (I can say this having done so for
more than 20 years now)
• It is the most inexpensive dosimetry and
dose imaging technology available
• New film models and readout techniques
promise
i improved
i
d accuracy andd precision
ii
over anything previously available
90Sr/Y
Planar Ophthalmic Applicator
Hinge
Steel Plug
5.3 mm
8.6 mm
1.0 mm
Ceramic
C
i containing
t i i
radioactivity
Cup
6 35 mm
6.35
10.3 mm
Window
0 10 mm thick
0.10
Source Geometries
1 cm
90Sr
planar
106Ru
planar
106Ru
concave
Typical Source Profiles
Tracerlab & ICN/Tracerlab
3M
Technical Operations
Manning Research
New England Nuclear
Atlantic Research Corp/Atomchem
Isotope Products Lab/Nucl.
Lab/Nucl Assocs.
Assocs
Amersham International
Peak Dose Rate
230 mGy/s
Calibrated Average
Dose Rate 170 mGy/s
Ophthalmic
p
Brachytherapy
y
py
Intraocular Tumor
106Ru/106Rh
Ophthalmic
Applicator
1 Gy
100 Gy
>700 Gy
106Ru/Rh
Concave Applicators
Eye
y Phantoms
Better Eye
y Phantoms
EBT-1 Film Exposed at a Distance of 2.62 mm
EBTfrom the Inner Surface of a CCX Plaque
Measurement Comparison of Ophthalmic Applicators
National Institute of Standards & Technology
USA
Chris Soares
National Physical Laboratory
UK
Tudor Williams
Radiation and Nuclear Safety Authority
Finland
Hannu Järvinen
Catholic University of Louvain
Louvain, St
St.-Luc
Luc Hospital
Belgium
Stefaan Vynckier
Algemeen Ziekenhuis Middelheim
Belgium
Bob Schaeken
University Hospital of Essen
Germany
Dirk Flühs
Results of Reference Dose Rate Determinations
Extrap. Extrap. GAF
GAF 0.3mm 0.3mm 0.4mm 1mm 1.2mm
Chamb. Chamb. Film
Film
TLD diamond scin TLD alanine
Source (NIST) (NPL) (NIST) (STUK) (UCL) (STUK) (NIST) (UCL) (AZM)
90Sr
NEN
0258
0.237
Gy/s
0.260* 0.229 0.258
Gy/s Gy/s Gy/s
0.248
Gy/s
---
0.278 0.308 0.272
Gy/s Gy/s Gy/s
106Ru
1.61** 1.82** 1.62
1.63** 1.40
1.99
1.69 1.75 1.49
BEBIG mGy/s mGy/s mGy/s mGy/s mGy/s mGy/s mGy/s mGy/s mGy/s
planar
106Ru
--BEBIG mGy/s
concave
--2.48 2.10*** 2.55
3.17
--2.79 2.89
mGy/s mGy/s mGy/s mGy/s mGy/s mGy/s mGy/s mGy/s
*from a contact measurement with a factor of 0.573 applied to correct to 1 mm
** from a contact measurement with a factor of 0.742 applied to correct to 1mm
***from a measurement at 1.2 mm with a factor of 1.082 applied to correct to “
Depth Dose Measurements of a 90Sr Ophthalmic Applicator
10
1
NIST RCF
R e l a tiv e d o s e r a
0.3 mm TLD
1 mm TLD
0.1
Al i
Alanine
Gradient at 1 mm:
6.5% per 0.1 mm
0.01
STUK diode
NIST EC
STUK IC
0.001
NIST scin
Essen scin
ACCEPT
Code
0.0001
0 00001
0.00001
0
200
400
600
800
Depth in material /mg cm -2
1000
1200
Depth Dose Measurements of a 90Sr Ophthalmic Applicator
2
1.75
NIST RCF
0.3 mm TLD
Re
elative dos
se rate
1.5
Gradient at 1 mm:
6.5% per 0.1 mm
1.25
1 mm TLD
Alanine
STUK diode
1
NIST EC
0.75
STUK IC
NIST scin
0.5
Essen scin
0.25
ACCEPT Code
0
0
200
400
600
800
Depth in material /mg cm-22
1000
1200
Depth Dose Measurements of a Planar
106Ru Ophthalmic Applicator
10
NIST RCF
1 mm TLD
R e l a tiv
v e d os e ra
1
STUK
diode
Gradient at 1 mm:
3% per 0.1 mm
0.1
NIST scin
Essen
scin
STUK
diamond
0.01
0.3 mm
TLD
Alanine
0.001
ACCEPT
Code
0.0001
0
400
800
Depth in material / mg cm
1200
-2
1600
Depth Dose Measurements of a Planar
106Ru Ophthalmic Applicator
1.5
1.25
R e l a tiv e d o s e r a
NIST RCF
Gradient at 1 mm:
3% per 0.1 mm
1 mm TLD
STUK
diode
1
NIST scin
Essen
scin
i
0.75
STUK
diamond
0.5
0.3 mm
TLD
Alanine
0.25
ACCEPT
Code
0
0
400
800
Depth in material / mg cm
1200
-2
1600
Depth Dose Measurements of a Curved
106Ru Ophthalmic Applicator
10
NIST RCF
R e l a t iv
v e d o s e ra
1
0.3 mm
TLD
1 mm TLD
Gradient at 1 mm:
2% per 0.1 mm
0.1
Alanine
STUK
diamond
0.01
STUK
diode
Essen
scin
0.001
ACCEPT
Code
0.0001
0
400
800
Depth in material / mg cm -2
1200
1600
Depth Dose Measurements of a Curved
106Ru Ophthalmic Applicator
1.25
NIST RCF
R e l a t iv
v e d o s e ra
1
Gradient at 1 mm:
2% per 0.1 mm
0.3 mm
TLD
1 mm TLD
0.75
Alanine
STUK
diamond
0.5
STUK
diode
Essen
scin
0.25
ACCEPT
Code
0
0
400
800
Depth in material / mg cm -2
1200
1600
Spread in Measurement Results
Source
90Sr
NEN
0258
106Ru
BEBIG
planar
106Ru
BEBIG
concave
Contact
1 mm
2 mm
3 mm 4 mm
5 mm 7 mm 10 mm
6.2%
(10)
9.6%
(8)
5.3%
(10)
3.4%
(10)
4.8%
(9)
8.8%
(9)
---
5.5%
(8)
10.5%
(9)
4.0%
(8)
6.1%
(8)
6.4%
(8)
6.8%
(8)
10%
(7)
8.2%
(8)
14%
(6)
4.8%
(8)
6.9%
(8)
7.3%
(8)
7.0%
(8)
9.4%
(8)
---
19%
(7)
18%
(8)
percentages
g are single
g standard deviations. Yellow values are for
All p
reference absorbed dose rate; white values are for relative central-axis dose.