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 quality assurance (QA) of medical radiation therapy systems. We implement state-of-the-art models and computations to make radiochromic film dosimetry and radiation therapy QA easy, fast, and accurate. Radiochromic.com is the result of continuous Research and Innovation.

Radiochromic.com users are Medical Physicists and Researchers. Read and follow these Tutorials carefully to obtain the most accurate results.

Radiochromic.com should work on all modern browsers.

Radiochromic film dosimetry

Different protocols for radiochromic film dosimetry can be applied with Radiochromic.com. Here, we present our recommended protocol for accurate radiochromic film dosimetry. This protocol is based on:

Méndez, I., et al. "A protocol for accurate radiochromic film dosimetry using Radiochromic.com." Radiology and Oncology 55.3 (2021): 369-378.

The dosimetry system

The dosimetry system for radiochromic film dosimetry 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
  • Technical drafts for frames and compression sheets for the Epson Expression 10000-12000XL and Epson Perfection V700-850 scanners can be found here.
The dosimetry system
The dosimetry system

Film handling
  • Keep films in a dry and dark environment.
  • Handle films with care, do not touch them without wearing gloves to prevent marks and scratches.
  • Keep films away from light whenever possible.
  • If films are submerged in water, minimize the time of submersion.
  • Do not bend films when cutting them. Use sharp scissors or, preferably, a guillotine.
  • Films should always keep the same orientation (i.e., portrait or landscape) on the scanner. Mark each film or film fragment to keep the orientation with the original film sheet and place them consistently on the scanner.
  • One way to preserve the orientation constant is to keep the long edge of the film parallel to the long side of the scanner bed, while films can be cut in rectangular fragments where the long edge of the fragment is parallel to the long edge of the initial film sheet.
Image acquisition
How to irradiate, scan and upload films
Step 1 (optional):
Prior to irradiation, scan the films that you will be using. If films are cut into fragments, scan them after cutting.
Scanning the films before and after irradiation delivers more accurate results. However, it compels the use of a frame to place the films at the same position on both occasions and, according to our experience, reduces the uncertainty of film doses by less than 0.5%. Consequently, scanning the films before irradiation is optional in this protocol.
Step 2:
Irradiate the films.
Step 3:
Wait for the polymerization to stabilize and scan the films.
For convenience, films are usually scanned 24 h after irradiation. Shorter waiting times are possible; however, in this case, the waiting-time window should be narrower (e.g., 24 ± 2 h or 30 ± 5 min). Different waiting-time windows are associated with different sensitometric curves. This protocol recommends using the same waiting-time window employed during the calibration to prevent avoidable uncertainties. Different waiting-time windows imply larger uncertainties and require re-calibration correction.
Step 4:
Upload the film scans to Radiochromic.com
How to scan films
Step 1:
Warm up the scanner (30-45 min).
Step 2:
Films, either entire films or film fragments, shall 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 several (e.g., five) empty scans to stabilize the scanner lamp.
Step 4:
Center the film on the scanner. A convenient way to do so is with a frame.
Positioning films on the scanner with a frame
Positioning films on the scanner with a frame
Step 5:
Always use the same scanning mode, either reflection or transmission, that was used for the calibration.
Step 6:
Films shall be in perfect contact with the surface of the scanner bed to avoid curling. In transmission mode, place a 2-4 mm thick glass or PMMA sheet on top of the film. The positioning of the compression sheet shall be consistent; therefore, either cover or keep free the autocalibration area for all the scans. In reflection mode, the scanner lid itself compresses the film adequately.
Step 7:
Select the scanning area.
Maintain a fixed scanning area by saving it into the scanning software settings. In this manner, pixel positions on the film match with scanner coordinates, which is imperative when applying lateral corrections or scanning before and after irradiation.
Step 8:
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.
A resolution of 50-75 dpi (0.51-0.35 mm) fits most applications. While for treatments using small fields, 100-150 dpi (0.25-0.17 mm) may be necessary. In this protocol, higher resolutions are discouraged because they produce larger noise and slow down film scanning and analysis.
Step 9:
Perform four or five repeated scans and discard the first one for each film.
Scanning
Scanning
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.
Basic principles

In this protocol, we expose a calibration procedure for external photon beams, yet, other methods, radiation sources, and applications are possible, provided that they observe four basic principles:

  • Calibrations are valid for films from the same lot; therefore, each lot of films has to be calibrated at least once. However, since films slowly autopolymerize over time, it is advisable to repeat lot calibrations from time to time. Furthermore, since film response depends on humidity and temperature, more accurate film doses can be expected when calibration and film dose measurements are done together.
  • Uncertainties in the absorbed reference doses will be translated into film dose uncertainties. Hence, it is important to maximize the accuracy of the reference doses. Generally, this can be achieved by irradiating at reference conditions and selecting ROIs with homogeneous doses.
  • To avoid the lateral response artifact, the ROIs with reference doses should be centered on the scan.
  • The reference doses should cover the range of doses of interest to prevent extrapolations.
Recommended calibration procedure
Step 1 (only with lateral correction):
If the calibration will include the lateral correction, acquire the image of an entire unexposed film.
You can use the non-irradiated scans of a film. Upload them as irradiated scans.
Unexposed film
Unexposed film
Step 2:
Cut a film into several (e.g., seven) strips with the longer side of the strips parallel to the lamp.
Calibration strips
Calibration strips
Step 3 (optional):
Scan the film fragments prior to irradiation.
Step 4:
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. If the calibration will include the lateral correction, irradiate the strips with approximately homogeneous doses by using a beam with flatenning filter and a 25 cm × 25 cm field.
Step 5:
Scan all the calibration strips simultaneously. The irradiated areas of the strips should be centered on the scan.
Step 6 (recommended):
The unexposed strip 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 7:
Click on CALIBRATION.
Introducing calibration data
Introducing calibration data
Step 8:
Select an existing study or insert a new one.
Step 9:
Insert an identifier for the calibration.
Step 10:
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 11 (only with lateral correction):
In order to apply lateral corrections, select an image of an entire unexposed film. Do not apply lateral corrections if the strips in your calibration film were not irradiated entirely with homogeneous doses.
Lateral correction
Lateral correction
Step 12:
Click on Reference doses. The ‘Dose ROIs’ menu will appear.
Dose ROIs
Dose ROIs
Step 13:
Associate reference doses to ROIs. The ROIs should be centered on the image (and on the scan). To provide enough statistics for the calibration while avoiding the lateral artifact, the length of the ROIs on the axis parallel to the scan should be between 1-4 cm approximately. A minimum of three dose ROIs is needed.
Step 14:
Click on Request calibration.
Step 15:
The calibration is in progress. The result will be saved in My Work.
In My Work
In My Work
Radiochromic.com provides the mean error of the calibration, which computes the difference between film doses after applying the calibration and reference doses. In our experience, calibrations have mean errors of around 1-2.5%. Larger errors may point to flaws in the procedure. Also, they can be expected for low doses since uncertainties in radiochromic film dosimetry grow fast for doses lower than 1.5 Gy. To reduce uncertainties when measuring low doses with radiochromic films, we recommend scaling the number of MUs.
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 the 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 doses

Convert film pixel values into doses.

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 3×3 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. To apply dose rescaling, before the irradiation, cut a strip from the film to measure. This strip should be irradiated with a known homogeneous dose and scanned together with the rest of the film (and the unexposed strip). Finally, select a ROI of the exposed strip centered on the scan and introduce its dose.
In Radiochromic.com, the re-calibration correction is optional and composed of inter-scan correction and dose rescaling.
Response correction
Response correction
Step 11:
Submit the request.
Step 12:
The dosimetry is in progress. The result will be saved in My Work.
Radiochromic film dosimetry is affected by many sources of uncertainty. An incorrect protocol for film irradiation and scanning, as well as inherent uncertainties of the dosimetry model, may produce errors in film doses, resulting in differences between the expected dose distribution and the dose calculated with film dosimetry. As a consequence, additional tests may be required to verify the accuracy of the dose distribution.
Uploads
Film upload

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 to improve the accuracy of your results.
Step 5:
Upload the film scans following irradiation.
Step 6 (optional):
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
Radiochromic.com does not record or use patient data. Do not enter patient data to identify items or studies.
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
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. The order of transformations is: first Flip, then Rotation, and finally Translation.
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) or Image Sum (Σ) are in blue. Click on the Export button to export them in CSV format.
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.
Average profiles:
Select a ROI and click on the Average button to obtain the average profile. Click on the Export button to export it in CSV format.
Average profile
Average profile
Image difference (Δ):
Analyze image differences, either absolute (i.e., A-B) or relative (i.e., 100(A-B)/B).
Image difference
Image difference
Image sum (Σ):
Analyze the result of adding both images (i.e., A+B).
Radiation therapy QA
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 by clicking on the Gamma button .
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 between global and local gamma normalization. Global gamma can be normalized at Dmax or a specified Dnorm.
Step 8:
Select dose tolerance as a percentage of Dmax or Dnorm (global normalization) or of the local dose (local normalization).
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 or Dnorm.
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. In order to optimize the γ-index results, doses in Image A will be scaled.
Both the automatic scaling in relative dosimetry and the automatic fine registration use evolutionary algorithms to optimize the gamma index results. Because of the random nature of evolutionary algorithms, repeated calculations can deliver slightly different results.
Optional: Tol. distribution
Distribution from which global gamma dose tolerances and the threshold dose are calculated. 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
Flatness and Symmetry

Calculate dosimetric characteristics of uniform beam profiles:

  • Position of the beam center.
  • Dose at the beam central position.
  • Field dimension: distance between the points with 50% (FWHM) of the beam central dose.
  • Flatness and Symmetry (Varian™): 100∗(Dmax−Dmin)/(Dmax+Dmin) 100∗max(D(z)−D(-z))/Dcenter

    Valid for photons and electrons. Defined within 80% of the field size (FS).

  • Flatness and Symmetry (IEC, Elekta™): 100∗(Dmax/Dmin) 100∗max(D(z)/D(-z)

    Valid for photon FS≥5cm. Defined within the flattened area, which has a margin of 1cm for 5≤FS≤10cm, 10% of the FS for 10<FS≤30cm, and 3cm for FS>30cm. [IEC 60976]

  • Penumbras: distance between the points with 80% and 20% of the beam central dose.

Step 1:
Click on the Flatness and Symmetry button .
Step 2:
Zoom a uniform rectangular field centered on the canvas.
Correct field
Correct field
Step 3:
Select a profile or an average profile and click on the Calculate button.
Correct profile
Correct profile
Step 4:
Flatness, symmetry, and other dosimetric properties of the beam are shown.
Flatness and symmetry results
Flatness and symmetry results
Troubleshooting 1:
The profile should encompass field size and penumbras. An incomplete profile will display an error message. Do not include other elements, which can interfere in the calculation.
Error
Error
Troubleshooting 2:
Complementary profiles (e.g., film pixel values) will display an error message. Even though you can calculate the complementary image with the tool Transform | Math, be aware that flatness and symmetry are properly calculated using doses or relative doses.
Error
Error
Troubleshooting 3:
The field should be centered on the canvas.
Error
Error
Starshot

Locate and obtain the dimensions of the radiation isocenter by analyzing a starshot test. The analysis will yield:

  • Number of detected beams.
  • Position of the fiducial/laser isocenter.
  • Position of the radiation isocenter.
  • Radius of the radiation isocenter.
  • Distance between fiducial and radiation isocenter.

Step 1:
Load an image of a starshot test (e.g., film, EPID, CR, etc.).
Starshot image
Starshot image
Step 2:
The axes of the star should have lower values than the background. If this is not the case, click on the Complement button in the Transform | Math menu to calculate the complementary image.
Complement pixel values
Complement pixel values
Step 3:
Click on the Starshot button . The Starshot menu will expand.
Step 4:
Lock the cursor and align it with the fiducial/laser isocenter if it is marked on the image. Otherwise, lock the cursor in a position close to the center of the star.
Lock the cursor
Lock the cursor
Step 5 (optional):
Prevent labels and other artifacts from interfering in the calculation by selecting a ROI
Step 6:
Click on the Calculate button. Results will show after few seconds. Click on Report to get them in a PDF file.
Results
Results
Step 7:
If the calculation fails to find the beams, modify cursor/fiducial position.
Excessive noise, large beam widths, beams too close to each other, image artifacts, etc., can induce errors in the location of the beams.
Troubleshooting 1:
The axes of the star have higher values than the background. Click on the Complement button in the Transform | Math menu to calculate the complementary image.
Troubleshooting 2:
The cursor is far from the center of the star. Lock the cursor in a position closer to the isocenter.
MLC Picket Fence

Check the accuracy of MLC positions. The test will show:

  • Positions of beam lines.
  • Leaves errors for both MLC banks.
  • Mean and maximum errors.
  • Positions of leaves out of tolerance and passing rate.

Step 1:
Load an image of a picket fence test (e.g., film, EPID, CR, etc.).
Picket fence image
Picket fence image
Step 2:
The beam lines should be horizontal and have higher values than the background. If this is not the case, transform the image by rotating it and/or calculating the complementary image.
Prepare the picket fence image
Prepare the picket fence image
Step 3:
Click on the Picket Fence icon and the MLC Picket Fence menu will expand.
Step 4:
Lock the cursor near the center of the MLC in the X axis (i.e., the position of the isocenter in the X axis). The field "Isocenter position X (mm)" can assist you with that and can easily correct EPID offsets with respect to the isocenter.
Lock the cursor
Lock the cursor
Step 5:
Delineate the ROI (i.e., the MLC region).
MLC ROI
MLC ROI
Step 6:
Select the MLC model. Introduce distance scaling (i.e., Source to Imager Distance / Source to Axis Distance), tolerance of the test, and leaf end threshold.
By default, the leaf end is located at the position of the 50% isodose between the peak of the signal and the background (i.e., the FWHM), which is appropriate when working with doses. You can change the threshold level to locate the leaf end more accurately when pixel values do not correspond to doses (e.g., with EPIDs).
Options
Options
Step 7:
Leave the Auto-correct translation checked if you want the application to adjust the the isocenter position in the x-axis. Leave the Auto-correct rotation checked if you want the application to remove any rotation of the beam lines.
Corrections
Corrections
Step 8:
Click on Calculate. The calculation will begin. Results will show after few seconds. Click on Report to get them in a PDF file.
Results
Results
The accuracy of the results depends on the image resolution and the signal-to-noise ratio. Better resolution and less noise produce more accurate results.
Troubleshooting 1:
The beam lines are vertical. Transform the image by rotating it.
Troubleshooting 2:
The beam lines have lower values than the background. Click on the Complement button in the Transform | Math menu to calculate the complementary image.
Troubleshooting 3:
There are many points out of tolerance outside the MLC region. Delineate the MLC region with the ROI tool.
No ROI error
No ROI error
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.
My Work menu
My Work menu
Archive / Restore studies:
Archived Studies are only accessible in My Work.
Edit studies:
Rename a study.
My Work buttons
My Work buttons
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