Video tutorials  

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  • Upload film scans (1:31)
  • Upload dose planes (0:39)
  • Calibrate film lots (1:15)
  • Obtain film doses (1:12)
  • Image analysis (2:18)
Step by step tutorials
Introduction

Radiochromic.com is a web application for radiochromic film dosimetry using Gafchromic™ films and flatbed scanners.

Radiochromic.com is the result of continuous Research and Innovation. We implement state-of-the-art methods to make radiochromic dosimetry easy, fast and accurate.

In order to obtain the most accurate results, it is very important to carefully read and follow this tutorial. Radiochromic film dosimetry is affected by many sources of uncertainty. Deviations from the recommended protocol may decrease the accuracy of the results.

The dosimetry system

The dosimetry system consists of:

  • Gafchromic™ radiotherapy/radiology films
  • a flatbed scanner
  • Our first option in terms of accuracy would be the Epson Expression 10000-12000XL, followed by the Epson Perfection V700-850 models, all of which have been extensively studied in the literature.
  • scanner software
  • Radiochromic.com

The recommended accessories are:

  • gloves
  • a guillotine
  • a frame to center the film on the scanner
  • a transparent compression (glass) sheet, when scanning in transmission mode
The dosimetry system
The dosimetry system

Film handling
  • Keep films in a dry and dark environment at the temperature and humidity at which they will be used for clinical purposes.
  • Handle films with care. Do not touch them without wearing gloves. Keep them away from light whenever possible.
Film processing
How to irradiate, scan and upload films
Step 1 (recommended):
Prior to irradiation, scan the films that you will be using.
Radiochromic.com employs the Multigaussian model for radiochromic film dosimetry. More accurate results have been found when combining the film response prior to and following irradiation.
On both occassions, films should be placed in the exact same position on the scanner. If films are cut into fragments, scan them after cutting.
Step 2:
Irradiate the films.
Step 3:
Wait for the films to stabilize and scan them.
Typically, films are scanned 24 h after irradiation. Shorter waiting times are possible, however, in this case, the window time should be narrower (e.g., 24 ± 1 h or 24 ± 1 min) and strict control of exposure and readout times for each film may be necessary.
It is recommended to follow the same waiting-time window employed during the calibration. Different waiting-time windows imply larger uncertainties, and require dose rescaling.
Step 4:
Upload the film scans to Radiochromic.com
How to scan films
Step 1:
Warm up the scanner (30-45 min).
Step 2:
Note the film lot number and mark each film or film fragment. Films should always keep the same orientation (i.e., portrait or landscape) on the scanner. Use the marks to place films consistently on the scanner.
Step 3:
Before acquisitions, and after pauses, perform five empty scans to stabilize the scanner lamp.
Step 4:
Center the film on the scanner with a frame.
Step 5:
Always use the same scanning mode. When scanning in transmission mode, use a transparent compression (glass) sheet on top of the film to avoid film curling.
Step 6:
Select the scanning area.
When applying lateral corrections, Radiochromic.com considers that the scanning area is centered on the axis parallel to the lamp. To prevent errors, we recommend using a fixed frame and always the same scanning area.
Step 7:
Acquire images with image type set to 48-bit RGB (16 bit per channel) and image processing tools turned off. Save the data as uncompressed TIFF files.
Excessive resolution will not improve the results but will slow down the calculations. We recommend using about 50-75 dpi in general. For small beams, 150 dpi may be necessary.
Step 8:
Perform four or five consecutive scans for each film and discard the first scan.
Scanning
Scanning
Upload film scans to Radiochromic.com
Up to five images can be uploaded for each series (irradiated and non-irradiated), with a maximum of 20MB for each image.
Step 1:
Click on FILM UPLOAD.
Introducing film data
Introducing film data
Step 2:
Select an existing study or insert a new one.
Step 3:
Insert an identifier for the film.
Step 4 (recommended):
Introduce film statistics.
Statistics assist you in describing your films. Furthermore, they are processed in order to improve the accuracy of your results.
Step 5:
Upload the film scans following irradiation.
Step 6 (recommended):
Upload the film scans prior to irradiation.
Film scans
Film scans
Step 7:
Select the film orientation with respect to the scanner lamp. This is CRITICAL if lateral corrections are applied.
Film orientation
Film orientation
Step 8:
Click on Upload scans. The average film scans will be calculated and uploaded. They will be saved in My Work.
Average film scans
Average film scans
In My Work
In My Work
Lot calibration

A calibration is necessary to convert the response of the dosimetry system into a dose distribution.

Radiochromic.com employs the Multigaussian model for radiochromic film dosimetry. Sensitometric curves are adjusted with splines, associating reference doses with their median pixel values in each channel. The lateral correction is calculated following the model proposed by Lewis and Chan.
Step 0:
Recalibrate often, we recommend once a month.
Step 1:
Cut a film into six to eight calibration strips.
Calibration strips
Calibration strips
Step 2 (recommended):
Scan the film fragments prior to irradiation.
Step 3:
Irradiate all but one of the strips with known (constant) doses. The doses should go from 0 Gy (the unexposed film fragment) to approximately 120 % of the maximum dose of interest. In order to apply lateral corrections, you need to irradiate the full width of the strips with (approximately) homogeneous doses (e.g., with 25 cm x 25 cm beams). In case you cannot cover the full width of the strips, do not apply lateral corrections.
Step 4:
Irradiate, scan and upload the film.
The unexposed film fragment can be used to correct inter-scan variations. We recommend to keep this fragment in the same position when scanning every film until a new calibration is made.
Step 5 (recommended):
In order to apply lateral corrections, scan an unexposed film and upload it.
You can use the non-irradiated image of a film. Preferably, upload scan images of several unexposed films to obtain the average unexposed film scan of your lot. Upload them as non-irradiated scans.
Unexposed film
Unexposed film
Step 6:
Click on CALIBRATION.
Introducing calibration data
Introducing calibration data
Step 7:
Select an existing study or insert a new one.
Step 8:
Insert an identifier for the calibration.
Step 9:
Select the calibration film.
Optional: Use non-irr scan
Unless unchecked, the calibration will make use of the information contained in the non-irradiated scan if it is present.
Optional: Cyberknife
There is a special calibration mode for films irradiated with Cyberknife™ beams. The application will localize the center of the beam inside the ROI.
Advanced options
Advanced options
Step 10 (recommended):
In order to apply lateral corrections, select a film containing a non-irradiated image. Do not select it if the strips in your calibration film were not irradiated entirely with homogeneous doses.
Lateral correction
Lateral correction
Step 11:
Click on Reference doses. The ‘Dose ROIs’ menu will appear.
Dose ROIs
Dose ROIs
Step 12:
Associate ROIs with their doses. Use ONLY the central part of the scan to avoid the lateral artifact. A minimum of three dose ROIs is needed.
Step 13:
Click on Request calibration.
Step 14:
The calibration is in progress. The result will be saved in My Work.
In My Work
In My Work
Cyberknife™

Radiochromic.com allows you to calibrate with fragments irradiated with Cyberknife™ fields.

Step 1:
Irradiate several fragments with known doses using Cyberknife™.
Cyberknife irradiation
Cyberknife irradiation
Step 2:
Irradiate, scan and upload the film.
Only the central part of the scanner should be used.
Step 3:
Click on CALIBRATION.
Step 4:
Select an existing study or insert a new one.
Step 5:
Insert an identifier for the calibration.
Step 6:
Select the calibration film.
Step 7:
Select Cyberknife.
Advanced options
Advanced options
Step 8:
Click on Reference doses. The ‘Dose ROIs’ menu will appear.
Step 9:
Associate ROIs with their doses. A minimum of three dose ROIs is needed. The Dose ROIs in the Cyberknife™ calibration are circles with known dose and diameter. For each ROI, introduce the diameter (d) and the dose (D), then select a rectangle that encloses it. The application will find the circle of diameter d with the highest dose inside the rectangle and assign it to dose D.
Dose ROIs
Dose ROIs
Step 10:
Click on Request calibration.
Step 11:
The calibration is in progress. The result will be saved in My Work.
Film dosimetry

Convert film scans to dose distributions.

Step 1:
Calibrate the film lot.
Step 2:
Irradiate, scan and upload the film.
Step 3:
Click on DOSIMETRY.
Introducing dosimetry data
Introducing dosimetry data
Step 4:
Select an existing study or insert a new one.
Step 5:
Insert an identifier for the dosimetry.
Step 6:
Select the film.
Step 7:
Select the calibration.
Optional: Noise reduction
Apply a square median filter to the dose distribution to reduce the noise (a 3x3 square median filter is recommended).
Advanced options
Advanced options
Step 8:
Click on Response correction.
Step 9 (recommended):
Inter-scan correction: select an unexposed ROI in order to correct inter-scan variations. Use the central part of the scan to avoid the lateral artifact.
The unexposed film fragment from the calibration can be used to correct inter-scan variations. We recommend keeping this fragment in the same position when scanning every film until a new calibration is made.
Step 10 (optional):
Dose rescaling: rescale doses in order to match the film dose with the known dose of a ROI.
Dose rescaling mitigates intra-lot variations as well as differences from the film processing protocol observed during calibration. Dose rescaling multiplies each dose with a constant factor derived from the known dose of the ROI.
Response correction
Response correction
Step 11:
Submit the request.
Step 12:
The dosimetry is in progress. The result will be saved in My Work.
Dose plane upload
Export dose planes from a TPS or a 2D dosimeter
Only square pixels are currently supported.
ADAC Pinnacle (Philips):
Planar Dose Computation -> Export Planar Dose -> Format: ASCII (Resolution: cm, Dose Units: Gy)
Eclipse (Varian):
Export dose plane → Dose absolute, Planar dose: 512 points, Burn marker pixels: No
iPlan (Brainlab):
Export → Dose → Select region, Dose Range and Step
Monaco and XiO (Elekta):
Dose profile → Dose plane output
MultiPlan (Accuray):
Plan → Export DICOM Data → Planar Dose
OmniPro I'mRT/I'mRT+ (IBA) - ASCII .opg file:
Export Data → Generic ASCII File → Entire file
PCRT 3D (Técnicas Radiofísicas):
Haces → Export → Placas → DICOM RT → Resolución: max.75 ppp, 16 bits
Radiochromic.com dose map:
My Work → Category: Dosimetry → Download
Contact user support if your TPS / 2D dosimeter is not listed.
Import dose distributions in CSV format

Import dose distributions in comma-separated values format. Doses should be in Gy and positions in mm. Follow the format of the example below:

Comma-separated values format
Comma-separated values format
Only square pixels are currently supported.
Upload dose planes to Radiochromic.com
Step 1:
Click on DOSE UPLOAD.
Introducing dose plane data
Introducing dose plane data
Step 2:
Select an existing study or insert a new one.
Step 3:
Insert an identifier for the dose plane.
Step 4:
Select the TPS or 2D dosimeter from where you have exported the dose plane.
Contact user support if your TPS / 2D dosimeter is not listed.
Step 5:
The upload button will appear. Select the dose plane file.
Step 6:
Once uploaded, the dose plane will be shown. Files are anonymized upon uploading. The dose plane can be found in My Work.
In My Work
In My Work
Image analysis

Process and analyze your results.

Images A and B:
Display one or two images.
Images A and B
Images A and B
Transformations:
Register both images using affine transformations.
Drag:
Use the middle mouse button to drag the Image A.
Cursor:
Read the image values under the cursor.
Profiles:
Vertical and horizontal profiles for both images are shown. Image A is in red, Image B is in green, and Image difference (Δ) is in blue.
Image analysis
Image analysis
Histograms:
Select the dose range of interest. Examine the distribution of doses with the histogram and other tools for statistical analysis.
ROIs and zoom:
Select Regions of Interest with the left mouse button. Zoom/unzoom using the right button.
Image difference (Δ):
Analyze image differences, either absolute (i.e., A-B) or relative (i.e., 100(A-B)/B).
Image difference
Image difference
Gamma index analysis

Compare dose distributions by evaluating the 2D γ-index.

Step 1:
Select evaluation (Image A) and reference (Image B) dose distributions.
Noise in the evaluation distribution artificially improves the γ-index. Given that film dosimetries are noisier than uploaded dose planes, the film dosimetry should be the reference distribution while the dose plane should be the evaluation distribution.
Step 2:
Pre-register both images by flipping, translating and rotating Image A.
Step 3:
If necessary, scale or increment the doses of Image A by a fixed value.
If you are using a dose plane calculated by the TPS, introduce the daily output of the accelerator measured on the day of the irradiation as dose scaling. Alternatively, if you are using a dose plane measured with a 2D dosimeter, introduce the dose scaling factor necessary to correct for the distance between the plane of the film and the plane of measurement of the dosimeter.
Step 4:
Open the Gamma index menu.
Introducing γ-index data
Introducing γ-index data
Step 5:
Select an existing study or insert a new one.
Step 6:
Insert an identifier for the gamma comparison.
Step 7:
Select normalization: local or global gamma.
Step 8:
Insert the dose tolerance (% of Dmax in the tolerance distribution).
Step 9:
Insert the distance tolerance in mm.
Step 10:
Insert the threshold dose. Points with doses lower than the threshold dose are excluded. The threshold dose is a percentage of Dmax.
Step 11:
If selected, the automatic fine registration will improve your manual registration.
Step 12:
Relative dosimetry: the application will consider that the images contain relative doses.
Both the automatic scaling in relative dosimetry and the automatic fine registration use evolutionary algorithms. Because of the random nature of evolutionary algorithms, repeated calculations can deliver slightly different results.
Optional: Tol. distribution
Dose tolerances and the threshold dose refer to the tolerance distribution. Either the reference or the evaluation dose distribution can be used.
Advanced options
Advanced options
Optional: Max. gamma
The maximum gamma value restricts the search space around each reference point.
Step 13:
The edges of the reference dose distribution have misleadingly high γ-index values. They are excluded by default with the automatic ROI. Alternatively, you can select a different ROI manually.
Registration and ROI
Registration and ROI
Step 14:
Click on Request gamma.
Step 15:
The gamma is in progress. The result will be saved in My Work.
In My Work
In My Work
In My Work:
Click on the Fast Gamma button to re-evaluate Gamma Index comparisons.
Fast Gamma
Fast Gamma
My Work

All your uploaded and calculated data are in My Work.

Open My Work:
Click on the Radiochromic.com logo to open My Work.
Open My Work
Open My Work
List of items:
Select a list of items according to Study and Category.
Archive / Restore studies:
Archived Studies are only accessible in My Work.
My Work menu
My Work menu
Open My Item:
Click on an Item from the list and examine it.
In My Item:
Open the item in Analysis, Download it, print a Report or ask for Support from My Item.
My Item buttons
My Item buttons