SCIENTIFIC NOTE

Practical IMRT QA dosimetry using Gafchromic film:a quick start guide

Nick Bennie1,2 • Peter Metcalfe2

Received: 26 August 2015 / Accepted: 5 April 2016 / Published online: 20 April 2016

� Australasian College of Physical Scientists and Engineers in Medicine 2016

Abstract This work outlines a method for using Gaf-

chromic film for dosimetry purposes, by scanning it with

currently available commercial scanners. The scanners

used were: Epson V800, Epson V700, Epson V37 series,

specifically a V370 and a Canon multi-function office

printer/scanner. The Epson scanners have 16 bit RGB

resolution, the Canon has 8 bit RGB (Red Green Blue)

resolution, and the V800 and V700 allow scanning in

transmission mode. The V700 uses an Epson White Cold

Cathode Florescent Lamp; the recently released V800 uses

an Epson light emitting diode (LED) light source, while the

V37 series uses a reflective mode and the Epson LED light

source. The Epson V37 series scanners are designed for

non-professional use so the cost has been kept at a low

‘‘entry level’’ point, so they would be a suitable option for a

department wanting to use Gafchromic film or with limited

needs that did not justify a more sophisticated and expen-

sive unit. Note that the V800 or V700 scanners are not

expensive in context, costing approximately the same as a

25 sheet box of Gafchromic film. The Canon was included

to demonstrate that a scanner with 8 bit RGB resolution can

be used for dosimetry. These general multi-function units

are available in most departments, and they would allow

Gafchromic film to be evaluated as a dosimetry tool

without a significant investment. Furthermore, they are

generally capable of scanning large format film

(425 9 350 mm) in one part. Although this is not neces-

sary for dosimetry, it is often useful for machine QA,

where dividing the film into two parts to ensure accurate

measurements is not practical. Moreover, this analytical

method uses software that is freely or commonly available,

particularly the image processing package ImageJ. Note

ImageJ v1.48 was the version used. The results demon-

strate that this method used with the scanners evaluated is a

practical method of using Gafchromic film as a dosimeter

for IMRT QA.

Keywords Gafchromic � LED light source � IMRT QA �ImageJ

Introduction

The North Coast Cancer Institute (NCCI), like many other

radiotherapy based physics departments, has a need for film

dosimetry, but they no longer have access to traditional wet

film, silver halide, and processing facilities so it was

decided to use Gafchromic radiochromic film [1] for

dosimetry and for assessing dosimetry in the transverse

plane of IMRT (Intensity Modulated Radiotherapy) QA

(Quality Assurance) studies. Gafchromic radiochromic film

has been considered difficult to work with, this may be

because it is treated as a direct replacement for traditional

wet processed, silver halide, film, whereas it has charac-

teristics that are different. The use of commercially

Presented as a Poster at EPSM 2012, The 36th Annual Engineering

and Physical Sciences in Medicine conference, Gold Coast, Australia,

2–6 December, 2012.

& Nick Bennie

nick.bennie@ncahs.health.nsw.gov.au

Peter Metcalfe

Metcalfe@uow.edu.au

1 Lismore Base Hospital, NCCI, Northern NSW Local Health

District, Lismore, NSW 2480, Australia

2 Centre For Medical Radiation Physics, University of

Wollongong, Northfield Avenue, Wollongong, NSW 2500,

Australia

123

Australas Phys Eng Sci Med (2016) 39:533–545

DOI 10.1007/s13246-016-0443-0

available flatbed scanners to scan this film further differ-

entiates it from the traditional methods used with silver

halide film.

General purpose commercial scanners are not optimised

for scanning Gafchromic film for dosimetric purposes

because the response of the scanner in the axis perpen-

dicular to the scan direction is non-uniform; this means the

derived doses vary more than the generally accepted tol-

erances for IMRT QA analysis [2–5].

Furthermore, the active layer of Gafchromic film is not

deposited uniformly, which may result in discrepancies in

derived doses that are greater than acceptable [6, 7]. Sev-

eral methods have been proposed to deal with this

including: Micke et al. [6–11].

The method presented here demonstrates a simple and

practical method using tools from a standard image pro-

cessing application, ImageJ Rasband, NIH [12]. The use of

standard tools may allow the reader to easily understand

and implement this method in their department [13].

The intention is to allow a user to fully understand

each step in the process. It demonstrates that scanners that

are generally available and software that is free or com-

monly available can be used for IMRT dosimetry. In

general, this would allow a department to evaluate Gaf-

chromic film for dosimetry without the need to purchase

additional equipment.

The method demonstrates that a function can be derived

(derived function) from the scanner film combination that

is approximately directly proportional with dose.

It is generally recommended that a scanner with 16 bit

resolution in transmission mode, such as the Epson V700

or V800 be used. An assessment of the Epson V37, which

works in reflective mode, indicated it was good, while the 8

bit resolution Canon (multi-function printer/scanner, model

designation for specific unit used Canon iRC3580i) which

works in reflective mode was assessed as acceptable.

Methods

The method chosen used a scan of the unexposed film as a

reference (correction map) because it is simple to under-

stand and implement, and it leads to a derived value as a

first approximation that is directly proportional to dose. As

such it is valid for IMRT QA for exposures of up to 50 Gy.

Note that this is a system correction that corrects the factors

from the scanner and the factors from the film.

Although the 3 channel method proposed by Gaf-

chromic Micke et al. [5] does not need an unexposed scan,

the processing method is complicated and when done by

proprietary software, the system is considered to be diffi-

cult to understand. Moreover, there is a significant cost

involved with this method which a department would need

to consider carefully before purchase. It was also noted that

Gafchromic do provide this software for evaluation on

request.

Theory

In general, and specifically for the scanners used, the

system response (pixel value) with respect to an absorbed

dose at a specified point of the film, and for a single

channel of a RGB scan, was modelled by a 3 term

hyperbolic function; see the Gafchromic whitepaper Gaf-

chromicVR [1].

PxðDÞ ¼ ðaþ bDÞðcþ DÞ

where PxðDÞ is the raw pixel value from the scan, D is the

dose the pixel has been exposed to, a, b, c which are

constants, then for an unexposed ‘‘Blank’’ film, D = 0,

giving

Pxð0Þ ¼ a

c

For a saturated film exposed to a very high dose, Limit as D

??

Pxð1Þ ¼ b

If b and c are small then this function may be approxi-

mated by a simple hyperbolic such that when the unexposed

‘‘Blank’’ is divided by the ‘‘Exposed’’ scan, the result is a

function that is approximately linear for a small c and b

Pxð0ÞPxðDÞ ffi 1þ D

c

Then the function is derived further:

Pxð0ÞPxðDÞ � 1 ffi D

c

So that it is directly proportional to dose, D.

For the Green channel of RGB data this relationship

holds reasonably well for most scanners.

For the Red channel it appears that the unexposed

‘‘Blank’’ was unstable. With regards to introduced noise, it

appears that more noise was introduced than could gener-

ally be compensated for. It appears the ‘‘Blank’’ is almost

transparent to red, which means the measured values are

near a limit of the amplitude resolution of the scanner,

leading to non-linear or truncation effects, resulting in

significant noise and scan to scan inconsistency.

For the Blue channel, the system sensitivity was notably

less than the Red or Green channels. It was noted that the

Gafchromic marker dye is active in the Blue channel.

Therefore the Green channel was considered the most

suitable to use with this method.

534 Australas Phys Eng Sci Med (2016) 39:533–545

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Recipe and hints for using different scanners

A sheet of Gafchromic film should be selected.

The film should be marked such that the orientation can

be replicated, while any other marks may be added for

identification and setup, e.g., to locate the treatment iso-

centre.

Note that a standard uncut piece of film is 254 mm 9

203 mm.

It is important to preserve the orientation of the film

from Blank scan to Exposed scan, particularly with EBT2,

because there is a significant change in system response if

the film is rotated. The orientation from Blank scan to

Exposed scan must be consistent.

Using the scanner

Acquire an unexposed scan of the piece of film to be

used (Blank).

Install the film in a phantom and expose it to IMRT

treatment.

Wait for approximately 1 h.

Acquire a scan of the exposed film. (Exposed)

Store scan files in the working folder of a workstation

computer.

Using Image processing software (ImageJ):

Convert 3 channel RGB image to 3 images, one for each

channel R,G, and B.

Select the image that represents the Green channel. The

other data are not required.

Convert data to 32 bit single precision format. This

preserves resolution during processing.

Apply an Average filter to both Blank and Exposed. This

enhances amplitude resolution.

Divide scan of Blank by scan of Exposed.

Subtract unity (1) from all pixels of image.

Apply Median filter to remove noise enhanced by

division process.

Multiply result by constant of proportionality (derivation

follows below). Result is now in units of Dose.

Use Resize function to convert image pixel resolution to

the dimensions of the active area in millimetres.

254 mm 9 203 mm if using standard size uncut film.

Use Minimum function to set all values less than 0 to 0.

Use the Maximum function to limit the highest value.

High values can be introduced by noise or markers on

the film, and they may cause confusion in an IMRT

comparison package such as SNC Patient (Sun Nuclear

Corporation). For example, if the planned data indicated

the maximum value was 250 cGy it would be reasonable

to limit the maximum of the film data to 300.

This data is referred to as Processed Scaled Measured Data

(PSMD).

Save the PSMD as an image in ‘‘Text Image’’ format.

Data in ‘‘Text Image’’ format can be easily converted to

a format that is recognised by IMRT QA analysis programs

such as SNC Patient. See ‘‘Appendix 2’’ section.

The dose distribution derived from film measurement

can be compared with the dose plane exported from the

Treatment Planning System (TPS).

There may be a small difference in the amplitude scale

that can be corrected by selecting the Relative comparison

mode of the IMRT analysis package.

Derivation of constant of proportionality

Select a pixel of film that was exposed to 2 Gy and derive

the processed measured value. The numerical value that

multiplies this derived value to equal 200 (200 cGy) is the

constant of proportionality. 2 Gy was chosen because it is

the most common fraction dose in radiotherapy.

Note that the pixel selected should have been exposed to

a known dose of 2 Gy. When the derived constant is

applied to other pixels, either on the same sheet of film, or

other sheets of film, exposed to a different distribution, but

prepared under the same conditions, then the pixels close in

value to the suggested calibration point at 2 Gy will be

reasonably accurately converted to dose. It is recognised

that the function is only approximately linear with dose. It

is recognised and addressed that for some scanners, par-

ticularly in the range 0–3 Gy, this will result in an IMRT

analysis not meeting general criteria.

Apply a calibration function using the calibrate function

from ImageJ

The response of some scanners to the Green channel with

dose was only approximately linear; for example, non-

linearity for the V700 between 0 and 3 Gy will result in

approximately a 5 % discrepancy, and if a constant of

proportionality is used and there is agreement at 2 Gy, then

there will be an apparent under response of 5 % at 1 Gy.

This is significant because it will result in errors in the

IMRT analysis that are more than the generally accepted

criteria. To address this, a simple calibration function can

be applied in ImageJ. There is no reason to suggest that the

active medium of Gafchromic film has a discontinuous

function with dose. Therefore if the function is described

accurately, there is no requirement for a multiple point by

point calibration. Note this correction appears to be scanner

specific. That is, it is related to the workings of the scanner

hardware or software and not to the conversion of the

active medium by absorbed dose.

The Power Function (ImageJ, y = Ax^B) is a simple

function that is suitable.

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To apply this calibration using the application ImageJ,

load the PSMD and create an image window with the same

dimensions, but with a 16 bit image type, and then use the

copy function to copy the 32 bit data to the 16 bit window.

Note that with ImageJ version 1.48v, 16 bit data must be

used for calibration and the data must be copied, do not use

the change Image Type function directly.

Note that 16 bit data is an integer so the data must be

scaled before conversion to maintain amplitude resolution.

Select the Calibrate function and then enter the fol-

lowing values for:

Measured: 0, 105, 200 and

Response: 0, 100, 200.

Select Function: Power. The data in the 16 bit window is

then calibrated and can then be saved in ‘‘Text image’’

format. It can also be easily converted to a format

suitable for use by an IMRT analysis program.

Results

Calibration- different system (scanner 1 film)

response

The scanners considered were: Epson V800, Epson V700,

and Epson V37 series, specifically, a V370 and a Canon

(Multi-function office printer/scanner).

Discussion

The graphs in Fig. 1 show that the scanners have various

system response functions. They can also be seen on the

reproduction of the scanned image. However, this may

depend on the quality of the print and the actual observer

because they are general purpose scanners optimised for

general office and photographic applications, and often

Fig. 1 Scanner calibration response for four different scanner systems a Epson V800 b Epson V700 c Epson V370 d Canon Multi-Function Unit

536 Australas Phys Eng Sci Med (2016) 39:533–545

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with significant cost constraints. This means they are

generally used to copy a document or photograph that

when evaluated by eye, the copy seen on a computer

monitor appears to be similar to the original. In modern

dosimetry however, assessment is based on the numerical

data evaluated in a computer system, evaluation is almost

never done by eye. Gafchromic film is not optimised to the

human visual system, such as certain silver halide films

were, so direct visual assessment should not be attempted

without careful consideration. The spectrum output of the

light source and spectral response of the detectors used in

these systems were not optimised for Gafchromic film.

For each scanner considered the system response of the

Green channel was a well behaved function and for most, it

was approximately linear with dose. With the V800, the

response was close to linear, from 0 to greater than 50 Gy

Fig. 2. The specific definition being the error associated

with any deviation from linearity would not result in a

significant error for IMRT analysis.

For scanners that operate in transmission mode (Canon

and V370), the graphs were best fit and did not indicate the

amount of system noise, so the useable range of the V370

was from 0 to approximately 20 Gy and the Canon from 0

to approximately 3 Gy. However, since the most common

fraction dose in radiotherapy is 2 Gy, these scanners can

still be considered useful.

It was noted that the system response of the Red channel

for those scanners that operated in transmission mode

(V800 and V700) was generally greater than for the Green

Fig. 2 Calibration graph for V700 Green channel to 300 cGy

comparing processed measured data versus Power Fit versus Linear

reference

Fig. 3 Data at 1 h post exposure, prepared with calibration constant for 1 h

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123

Fig. 4 Data at 16 h post exposure. Note approximately 8 % further development of film

Fig. 5 Data at 16 h analysed using relative mode. (100 % of points pass)

538 Australas Phys Eng Sci Med (2016) 39:533–545

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channel. However, a pure system response is not as

important as the resulting signal to noise ratio. This system

has 2 major components, the film and the scanner, both of

which are sources of noise. The noise associated with the

scanner can be reduced by increasing the sample time. If

the resulting increase in scan time is not significant, to

achieve the same signal to noise ratio for the Green channel

as for the Red channel, then the greater sensitivity of the

Red channel should not be a major consideration in the

overall choice.

The recommendation to use the Green channel was

based on the overall properties; especially the property that

it was approximately linear with dose. This does not pre-

clude the use of the other channel data, which for certain

applications may be suitable, it is a recommendation for

general use that enables a simple method that can be easily

understood and implemented.

To address the issue of system noise and scanner stability

it was determined to scan at a significantly higher spatial

resolution than required. With the Epson scanners this

increases the scan time, which in turn stabilises the response

of the scanner and as the high resolution pixels are down

filtered to the required resolution (1 mm/pixel for IMRT

QA), eliminates a significant portion of the system noise.

To address the issue of noise introduced by dividing by

unexposed scan, a Median filter effectively removed noise

without affecting the spatial and amplitude resolution very

much. A median filter (Gonzalez and Woods [14], Chap. 3)

is a type of Order-statistic (nonlinear) filter. Median filters

provide excellent noise reduction with considerably less

blurring than linear smoothing filters and are particularly

effective for impulse noise.

Explanation of calibration values

Since the data had already been multiplied by a constant

such that a measured value of 200 equates to 200 cGy, then

in the calibration window a value of 200 was entered for

the measured and response. This was also the case for the

zero value, where from derivation a measured value of zero

equates to a zero dose. However, the response function for

the systems was only approximately linear which caused a

discrepancy at values other than 0 and 200. The discrep-

ancy at 100 cGy was approximately 5 %, so a measured

value of 105 equated to 100 cGy. When a calibration

function of the form y = Ax ^ B (Power) was applied, it

gave a good agreement in the range to approximately

300 cGy. This function has 2 degrees of freedom (A, B),

and as such is fully specified by the 3 data points.

Note again that there may be a small difference in the

amplitude scale when this data is compared to the planned

data in the IMRT comparison package, but it can be cor-

rected by selecting the Relative comparison mode in the

IMRT analysis package. This is valid because the cali-

brated data is effectively directly proportional to dose.

Referring to Table 1, the data are for the range 0–3 Gy.

For the range beyond 3–50 Gy it is not necessary to apply

the correction to meet the IMRT criteria discussed. As

discussed the function is only approximately linear,

therefore for a different target dose, for example 15 Gy, the

proportional constant for the V800 is 675 and for the V700

is 750. This results in approximately a 4 % absolute error

for values near 2 Gy, however as the VanDyk criteria [15]

is generally applied for IMRT, then the global error is

approximately 0.5 %. This assumes that if the target dose is

15 Gy, then the maximum dose will be close to 15 Gy.

Examples of clinical QA use

An example set of results for a Prostate IMRT treatment is

presented below Figs. 3, 4 and 5.

A general criterion for assessing IMRT is by the Gamma

method [16] using 3 % and 3 mm applied as global.

Applied as global, which means calculating the percentage

difference relative to the maximum value of all the points

assessed [15]. However, since film is considered to be a

high spatial resolution device it is common to use 4 % and

2 mm. All of the scanner systems returned accept-

able passing results, achieving[99.5 % of points passing

the above criteria for a clinical IMRT treatment. Note 3 %

3 mm and 4 % 2 mm are the assessment criteria commonly

used at NCCI for IMRT analysis.

Table 1 Tabulated values of a pixel exposed to 200 cGy, the resulting proportional constant and the correction required at 100 cGy for each of

the scanners in the range 0–300 cGy

Processed value of pixel

exposed to 200 cGy

Proportional

constant

Correction at

100 cGy

Epson V800 0.308 650 103.0

Epson V700 0.282 710 105.0

Epson V370 0.760 263 105.0

Canon 0.714 280 107.0

Gafchromic EBT3 film

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This set of results was obtained using the Epson V700,

but all the other evaluated scanners achieved[99.5 % %

of points passing for this case.

The initial scan was acquired at 1 h post exposure. A

subsequent scan for each scanner was acquired at 16 h post

exposure, and it was found that the derived function had

increased by approximately 8 %. This result was then

assessed using the Relative mode of application SNC

Patient, which allows normalisation between the TPS cal-

culated and the measured dose. The second example is the

subsequent scan assessed in Relative mode where once

again, all the assessments returned [99.5 % of points

passing.

Conclusion

Various scanners were used and an appropriate calibration

method that encompasses these scanners has been outlined.

The results are generally accurate to the tolerance required

for IMRT analysis, for example, Gamma criteria of 3 %

3 mm or 4 % 2 mm. This means the film/scanning system

errors were much less than this criteria and as such, a valid

analysis was achieved for treatment delivery.

The recommendation would be to use the Epson V800

scanner based on the characteristics of the LED based light

source. The Green channel appears to be well matched to

Gafchromic film such that a near linear response was

achieved from the derived function from 0 to 50 Gy. This

range covers almost all realistic treatment fractions,

including those associated with SBRT and SABR tech-

niques. Furthermore it appears to be more stable than the

Cold Cathode light source of the V700, both from scan to

scan and in the uniformity of the response across the

scanner. The V800 scanner is not that expensive, being

approximately the same cost as a standard box of Gaf-

chromic film.

However, if no specialised scanner is available, the

method showed that acceptable results in the range 0–3 Gy

were achievable with general document scanners such as

the Canon multi-function office unit evaluated, and which

are ubiquitous in modern departments. Furthermore, most

of these units can scan in A3 size, which although not

required for Patient QA dosimetry, is useful for some

machine dosimetry where measurements are required over

a large field.

The Epson V37 series was interesting because it also

uses an LED light source and the Green channel had a well

behaved and stable response over 20 Gy. However the

linearity of this response was only reasonable to 3 Gy.

Higher exposures would require a more complex calibra-

tion function. Because the V700 and V800 scanners which

operate in transmission mode and are superior, were not

that expensive, no further investigations were carried out

on the V37 series.

Acknowledgments Image processing package ImageJ available

from: National Institutes of Health, Bethesda, MA, USA Web site:

http://imagej.nih.gov/ij. Version used was ImageJ 1.48v Note some

functions may not be available in earlier versions and the authors have

no control over future versions of ImageJ. Gafchromic refers to a

range of Radiochromic film products supplied by: Ashland Speciality

Ingredients, International Speciality Products, 1361 Alps Road

Wayne • NJ, USA. Primarily Gafchromic EBT3 from Lot# 07281402

was used for this study. The Epson range of scanners was supplied by:

Seiko Epson Corp.Nagano, Japan. The IMRT evaluation program

used was SNC Patient v6.5 supplied by: Sun Nuclear Corporation,

Melbourne, FA, USA.

Appendix 1

Use of a scanner with 8 bit dynamic range

in reflective mode

The basic problem of using 8 bit resolution is that it only

allows 256 values to cover the range of interest. If, for

example, we were interested in a dose range from 0 to

250 cGy, this could possibly allow 1 cGy per division as a

best case. However, the Canon office scanner returned a

pixel value (in the Green channel) of 0 cGy as 136 and for

250 cGy the pixel value was 72. Therefore there were only

64 divisions to cover 250 cGy, which resulted in 4 cGy per

division. Furthermore, because the response was non-linear

the step per division will be greater at parts of the range.

Note that this was the raw scanner values, not the derived

function. This resulted in an amplitude resolution of

approximately 2 % of the range. A system resolution of

better than 1 % is generally required for IMRT QA, in

order to discern dosimetric errors of the order of 3 %.

Acceptable amplitude resolution can be achieved by

scanning at a high spatial resolution and then down filtering

to the required spatial resolution (generally 1 mm/pixel),

while enhancing the amplitude resolution in the process.

Note that aliasing was addressed as the light scattering

properties of Gafchromic film led to a distribution of values

for any measurement. This distribution acted effectively as

an anti-aliasing filter which, for the Canon printer, worked

well in the range from 0 to 3 Gy.

Appendix 2

Using an Epson scanner and the Epson Scan

software application

The specific models used were the Epson V800, V700, and

V370.

540 Australas Phys Eng Sci Med (2016) 39:533–545

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It was assumed that the scanner had been set up

according to the manufacturer’s recommendations and

connected to a PC (Windows 7), and the Epson Scan

software had been loaded.

A 25 9 20 cm film area guide or template should be

prepared for the V800 and V700 scanners such that the

piece of film may be placed accurately in the active area of

the scanner. An area guide was supplied with the V800 and

V700 scanners, but a simple right angle template was found

to be more practical.

For reflective mode, the scan area can extend to the

scanner bezel. The film can be accurately located against

the edge of the bezel so a separate area guide is not

required.

Activate the Epson Scan software application and ensure

that the acquisition parameters are as specified, that all the

colour corrections are switched off, then acquire RGB 48

bit, and save as file type.TIF.

Acquire the full area of the film (254 9 203 mm) and

specify a high spatial resolution such as 508 dpi (20 dpmm).

Save the pre-exposure ‘‘Blank’’ and the post-exposure

‘‘Exposed’’ scans in a suitable working directory. Since

these files can be large, it is recommended to save them on

the local hard drive of the scanner workstation.

Using the Canon office scanner

The Canon scanner works in reflective mode and the scan

area extends to the scanner bezel. The edge of the bezel can

be used to accurately locate the film so a separate area

guide is not required. However, ensure that the film is re-

positioned accurately between the Blank scan and Exposed

scan. Since these are general office scanners, the scanner

should be replicated between scans as far as possible, so be

aware that other users may leave unwanted marks on the

scanner.

To acquire a scan:

Select maximum spatial resolution (for the Canon this

was 600 dpi)

Select Colour

Select file type JPG (note several other file types are

acceptable to ImageJ, JPG is for Canon)

Select save file option. On the Canon the file is sent to

the users email address.

The Canon does not save the file in RGB format, so to

prepare the file for processing, open in ImageJ.

Use the Rectangle select tool to mark the extent of the

film.

Use Image ? Crop. This extracts the specified area.

Use Image ? Type ? RGB stack. This converts the

image to Type RGB

Save as.TIF to the working directory

This should be done for both the Blank and Exposed.

Note regarding JPG file format used by the Canon

scanner. JPG is the image format used by the Canon

multi-function scanner. Taken in context that software is

part of the system, the use of JPG by Canon is a com-

ponent of the resolution that can be achieved by the

scanner. The operator has no control over the compres-

sion level used. It could be assumed that it is optimised

by Canon, however the end point is the resolution that is

achieved considering the unit as a system including the

software.

Process data using application ImageJ

Data processing in ImageJ is done using ImageJ Macros.

These are scripts which list the commands. They also form

a summary documentation of the required steps. They are

listed below.

To run a macro in ImageJ, use:

File ? Open and select the macro (it should be saved

with extension.ijm)

The Macro window should open, then from the Menu

bar on the Macro window:

Select Macros ? Run Macro

It is assumed the scanned image files (Blank & Exposed)

are in the working directory.

Using ImageJ:

Open image file (RGB) of the Pre-Exposure image

(Blank).

Run macro: IJmacro_PreProcess_BLANK.ijm

Open image file (RGB) of the Post-Exposure image

(Exposed).

Run macro: IJmacro_PreProcess_EXPOSED.ijm

The pre-processed but uncalibrated image of the exposed

film should be open at this point.

If there are faults in the image such as pin holes from the

phantom, these can be edited. To remove pin holes, draw a

small rectangle around the pin hole, and then apply theMedian

filter with a radius 20. When complete, proceed to next step.

Australas Phys Eng Sci Med (2016) 39:533–545 541

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Run macro: IJmacro_Calibrate_V800_EBT3_LowRange.

ijm

The calibrated data is now saved as a Text Image in file:

Dose_Cal_Text_254x203.txt

This file can be converted to a format that can be read in

conjunction with software application SNC Patient using

the following steps:

Convert the file to a.csv file using MS Excel. Open the

Text Image file using Excel, specify Tab delimited data.

Then save file as type.csv (comma separated variable).

Pre-pend a header, such that the application SNC Patient

recognises the data as type XiO.

Use Batch file: Add_Header_to_csv_file.bat. This batch

file can be run from a CMD prompt with the name of the

file to be converted as 1st parameter. See below. Or right

click the file to be converted and select Open with, then

select batch file.

C:\!Data\254data[Add_Header_to_csv_file.bat

Dose_Cal_Text_254x203.csv

This batch file is listed below. The converted file can

now be read into the application SNC Patient. The

data is now in units of Dose (cGy). The file name is:

Dose_Cal_Text_254x203.csvX

Macro: IJmacro_PreProcess_BLANK.ijm

// This ImageJ macro converts a RGB to single channel (G) 32b 1016x812// The converted image is saved in same dir with name BLANK.tif//print("IJmacro_Preprocess_BLANK v1 24june2015")print(" ")//// Note it is Required that the Blank RGB file is open and is the only image open in ImageJ.//Fname = getTitle;print("Filename = "+Fname);//WDir = getDirectory("image");print("Working directory: "+WDir);//run("Stack to Images");selectWindow("Red");close();selectWindow("Blue");close();//selectWindow("Green");run("32-bit");run("Mean...", "radius=2");run("Rotate 90 Degrees Left");run("Size...", "width=1016 height=812 average interpolation=Bilinear");run("Grays");saveAs("Tiff", WDir+"BLANK.tif");close();print ("Macro complete");// // End

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Macro: IJmacro_PreProcess_EXPOSED.ijm

// This ImageJ macro converts a RGB to single channel (G) 32b 1016x812// The converted image is saved in same dir with name EXPOSED.tif//// The first stage of process is then run, using the stored Blank data.// print("IJmacro_PreProcess_EXPOSED v1 24june2015")print(" ")//// Note it is Required that the Exposed RGB file is open and is the only image open in ImageJ.// it is required that the processed Blank is stored in filename: BLANK.tif//Fname = getTitle;print("Filename = "+Fname);//WDir = getDirectory("image");print("Working directory: "+WDir);//run("Stack to Images");close("Red");close("Blue");//selectWindow("Green");run("32-bit");run("Mean...", "radius=2");run("Rotate 90 Degrees Left");run("Size...", "width=1016 height=812 average interpolation=Bilinear");run("Grays");saveAs("Tiff", WDir+"EXPOSED.tif");close();print ("PreProcess Exposed RGB data complete");//open(WDir+"\\EXPOSED.tif");open(WDir+"\\BLANK.tif");//imageCalculator("Divide create 32-bit", "BLANK.tif" , "EXPOSED.tif" );//close("BLANK.tif");close("EXPOSED.tif");////selectWindow("Result of BLANK.tif");run("Subtract...", "value=1");run("Median...", "radius=2");run("Min...", "value=0");run("Multiply...", "value=1000");resetMinAndMax();saveAs("Tiff", WDir+"RPDx1000_32b_1016x812.tif");print ("RPD Raw Processed Data written to file: RPDx1000_32b_1016x812.tif");run("Size...", "width=254 height=203 average interpolation=Bilinear");

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saveAs("Text Image", WDir+"RPDx1000_Text_254x203.txt");close();//open(WDir+"RPDx1000_32b_1016x812.tif");//// Leave RPD file open, ready to run appropriate calibration macro.//print ("Macro complete");// // End

Macro: IJmacro_Calibrate_V800_EBT3_LowRange.ijm

// This ImageJ macro applies a Calibration to a 32b 1016x812 image// The converted image is saved in same dir as both a 32b Tif and as a 254x203 Text Image//print("IJmacro_Calibrate_V800_EBT3_LowRange v1 24june2015")print(" ")//// Note that the 32b 1016x812 image MUST be open and is the only image open in ImageJ.//Fname = getTitle;print("Filename = "+Fname);//WDir = getDirectory("image");print("Working directory: "+WDir);////// Enter Rm200 value - EBT3 with V800 -> approx 650// Note data is x1000// Note set max value is dependent on range, expected max, change as appropriate//run("Multiply...", "value=0.65");run("Min...", "value=0");run("Max...", "value=400");//// Prepare to run Calibrate - create a 16b window// Note do not convert direct to 32b as it will re-scale the dataselectWindow(getTitle);run("Copy");run("16-bit");run("Paste");resetMinAndMax();//

run("Calibrate...", "function=Power unit=[Gray Value] text1=[0.0 103.0 200.0 ] text2=[0.0 100.0 200.0 ]");//// Covert back to 32brun("32-bit");saveAs("Tiff", WDir+"Dose_Cal_32b_1016x812.tif");//run("Size...", "width=254 height=203 average interpolation=Bilinear");saveAs("Text Image", WDir+"Dose_Cal_Text_254x203.txt");close();////print("Calibrated Data saved to: Dose_Cal_32b_1016x812.tif & Dose_Cal_Text_254x203.txt ");print("Macro Completed ");exit// End

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References

1. GafchromicVR EBT (2010) Self-developing film for radiother-

apy dosimetry. ISP White Paper

2. Lewis D, Chan MF (2015) Correcting lateral response artifacts

from flatbed scanners for radiochromic film dosimetry. Med Phys

42(1):416–429

3. Williams MJ, Metcalfe PE (2011) Radiochromic film dosimetry

and its applications in radiotherapy. University of Wollongong,

Wollongong

4. Butson MJ, Cheung T, Yu PKN (2006) Scanning orientation

effects on Gafchromic EBT film dosimetry. Australas Phys Eng

Sci Med 29(3):281–284

5. Alnawaf H, Peter KN, Butson M (2012) Comparison of Epson

scanner quality for radiochromic film evaluation. J Appl Clin

Med Phys 13(5):3957

6. Micke A, Lewis DF, Yu X (2011) Multichannel film dosimetry

with nonuniformity correction. Med Phys 38(5):2523–2534

7. Kairn T, Aland T, Kenny J (2010) Local heterogeneities in early

batches of EBT2 film: a suggested solution. Phys Med Biol

55(15):L37

8. Hu Y, Wang Y, Fogarty G, Liu G (2013) Developing a novel

method to analyse Gafchromic EBT2 films in intensity modulated

radiation therapy quality assurance. Australas Phys Eng Sci Med

36(4):487–494

9. Borca VC, Pasquino M, Russo G, Grosso P, Cante D, Sciacero P,

Tofani S (2013) Dosimetric characterization and use of GAF-

CHROMIC EBT3 film for IMRT dose verification. J Appl Clin

Med Phy 14(2):4111

10. Hardcastle N, Basavatia A, Bayliss A, Tome WA (2011) High

dose per fraction dosimetry of small fields with Gafchromic

EBT2 film. Med Phys 38(7):4081–4085

11. Mendez I, Hartman V, Hudej R, Strojnik A, Casar B (2013)

Gafchromic EBT2 film dosimetry in reflection mode with a novel

plan-based calibration method. Med Phys 40(1):011720

12. Rasband WS (2012) ImageJ: image processing and analysis in

Java. Astrophys Source Code Libr 1:06013

13. Abramoff MD, Magalhaes PJ, Ram SJ (2004) Image processing

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14. Gonzalez RC, Woods RE (2008) Digital image processing, 3rd

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15. Low DA, Dempsey JF (2003) Evaluation of the gamma dose

distribution comparison method. Med Phys 30(9):2455–2464

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missioning and quality assurance of treatment planning comput-

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Batch File to Pre-pend header: Add_Header_to_csv_file.bat

ECHO OFF

REM Add_Header_to_csv_file.bat v1 24June2015 REM Batch file to Pre-pend a XiO format header to a dose plane file for SNC Patient. REM Data should be in text format as a .csv file REM Normally this is prepared from an ImageJ text image (.txt), which is converted to .csv using MS Excel REM Run by Right click on file to be converted, and then select Open With ->Add_Header_to_csv_file.bat REM Can also be run from the command line with the name of file to be converted as 1st parameter.

ECHO %~1

CMD /C " ECHO X000111,,,,, > "%~1X" " CMD /C " ECHO DateTime,D18/12/2014,DocNum 1234,D11223344,, >> "%~1X" " CMD /C " ECHO PatientID,P111111,,,, >> "%~1X" " CMD /C " ECHO PlaneDesc,T: 0.00 cm,,,, >> "%~1X" " CMD /C " ECHO DoseUnits, cGy,-100, -1.0 cGy, Abs, >> "%~1X" " CMD /C " ECHO CompfType,-1,,,, >> "%~1X" " CMD /C " ECHO FieldSizeDefDist,-1,,,, >> "%~1X" " CMD /C " ECHO CollWidLenQAplane,-1,-1,,, >> "%~1X" " CMD /C " ECHO OutputWidLenQAplane,-1,-1,,, >> "%~1X" " CMD /C " ECHO QAssd,-1,,,, >> "%~1X" " CMD /C " ECHO QAdepth,-1,,,, >> "%~1X" " CMD /C " ECHO QAedens,-1,,,, >> "%~1X" " CMD /C " ECHO Upperleft,-125,110,,, >> "%~1X" " CMD /C " ECHO CalcGridResmm (x,y,z),1,1,1 >> "%~1X" " CMD /C " ECHO DosePtsxy,254,203,,, >> "%~1X" " CMD /C " ECHO DoseResmm,1,,,, >> "%~1X" "

CMD /C " TYPE "%~1" >> "%~1X" "

REM PAUSE EXIT

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