Video tutorials  
  • Upload film scans (1:31)
  • Upload dose planes (0:39)
  • Calibrate film lots (1:15)
  • Obtain film doses (1:12)
  • Image registration (1:25)
  • Starshot test (0:30)
  • Picket Fence (0:43)
  • Coincidence light-radiation (1:08)
  • Radiation field (0:55)
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 lamp 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 or 3M pixels 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 film orientation. This is CRITICAL if lateral corrections are applied. Click on the arrows to select the direction of movement of the scanner lamp on the film scans.
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. Images can have up to 3M pixels.
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
Analysis
Selection:
Select one or two images for display.
Images A and B
Images A and B
LUT:
Select between different color lookup tables.
Pixel units:
Pixel units can be Gy, cGy, or pixel values.
Alpha:
Select the level of transparency/opacity of the image.
Transformations:
Apply affine transformations on the image. The order of transformations is: first Flip, then Rotation, and finally Translation. Math will multiply each pixel in Image A by the first parameter and add it the second parameter. Rotate in 90º steps by clicking on . Calculate the complement image by clicking on .
Analysis: Image A
Analysis: Image A
Histogram:
Select the range of values of interest. Examine the distribution of values with the histogram and the statistical analysis.
Analysis: Image A. Histogram
Analysis: Image A. Histogram
Image calculator:
Calculate the image which is the difference (i.e., A-B), relative difference (i.e., 100(A-B)/B), or addition (i.e., A+B) of images A and B.
Global controls:
Synchronize the range of values of images A and B.
Analysis: Image A and B
Analysis: Image A and B
Drag:
Use the middle mouse button to drag the Image A.
ROI:
Select Region of Interest with the left mouse button or with the ROI button .
Zoom:
Zoom/unzoom using the right mouse button or the zoom buttons: .
Cursor:
Read the image values under the cursor. Lock the cursor by clicking on .
Profiles:
Vertical and horizontal profiles for both images are shown. Image A is in red, Image B in green, and Image calculator in blue. Select the Profile export step and click on the Export button to export them in CSV format.
Image canvas
Image canvas
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
Registration

Register two images.

Step 1:
Load two images to register.
Step 2:
Pre-register both images by flipping, translating, and rotating Image A.
Step 3:
Click on the Registration icon .
Step 4:
Introduce the inputs of the Registration.
Registration: inputs
Registration: inputs
Input / Apply Relative dosimetry:
The registration translates and rotates Image A. By applying Relative dosimetry, it will also change the Math factor that multiplies A pixel values.
Input / ROI (optional):
Select the points that will be included in the registration with a ROI. Otherwise, the registration will use all the pixels on both images.
Step 5:
Click on Calculate. After few seconds, the registration will apply an affine transformation on Image A to register both images.
Registration: result
Registration: result
Troubleshooting 1:
If the images are too far away from each other or the rotation between them is too large, the registration will fail. Pre-register both images previously.
Troubleshooting 2:
The rotation may fail if one image has perfect circular symmetry.
Troubleshooting 3:
The registration expects similar dose distributions (on absolute or relative values). Registration of images with similar shapes but completely different pixel values may fail.
Registration uses evolutionary algorithms to optimize the transformation. Repeated calculations can deliver slightly different results because of the random nature of evolutionary algorithms.
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. Alternatively, register them with the Registration functionality.
Step 3:
If necessary, scale or increment the doses of Image A by a fixed value with Transform / Math.
If you are using a dose plane calculated by the TPS, you can introduce the daily output of the accelerator as dose scaling. If you are using a dose plane measured with a 2D dosimeter, you can 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 .
Step 5:
Introduce the inputs of the Gamma.
Gamma: inputs
Gamma: inputs
Input / Study:
Select an existing study or insert a new one.
Input / ID:
Insert an identifier for the gamma comparison.
Input / Normalization:
Select between global and local gamma normalization. Global gamma can be normalized at Dmax or at a specified Dnorm.
Input / Tolerance Dose:
Select dose tolerance as a percentage of Dmax or Dnorm (global normalization) or of the local dose (local normalization).
Input / Tolerance Distance:
Insert the distance tolerance in mm.
Input / Threshold:
Insert the threshold dose. Points with doses lower than the threshold dose are excluded. The threshold dose is a percentage of Dmax or Dnorm.
Input / Tolerance Distribution:
Select the distribution from which global gamma dose tolerances and the threshold dose are calculated. Either the reference or the evaluation dose distribution can be used. (Default: Evaluation)
Input / Fine registration:
If selected, the automatic fine registration will improve your manual registration.
Input / Relative dosimetry:
If selected, 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. Repeated calculations can deliver slightly different results because of the random nature of evolutionary algorithms.
Input / Maximum gamma:
The maximum gamma value restricts the search space around each reference point. (Default: 2.0)
Input / ROI (optional):
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.
Step 6:
Click on Calculate. The gamma is in progress. The result will be saved in My Work.
In My Work
In My Work
Step 7:
You can change Gamma inputs to launch several Gamma Index calculations in parallel. For instance, you can change tolerances, apply relative dosimetry, etc., and click on Calculate again.
In My Work:
Click on the Fast Gamma button to re-evaluate Gamma Index comparisons.
Fast Gamma
Fast Gamma
Starshot

Locate and obtain the dimensions of the radiation isocenter by analyzing a starshot test.

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 to calculate the complementary image.
Starshot : complement
Starshot : complement
Step 3:
Click on the Starshot button .
Step 4:
Introduce the inputs of the test.
Starshot: input
Starshot: input
Input / Fiducial:
Lock the cursor and align it with the fiducial/laser isocenter if marked on the image. Otherwise, lock the cursor in a position close to the center of the star.
Input / ROI (optional):
Prevent labels and other artifacts from interfering in the calculation by selecting a ROI.
Step 5:
Click on Calculate. Results will show after few seconds.
Starshot: output
Starshot: output
Output / Isocenter coordinates:
Position of the radiation isocenter.
Output / Isocenter radius:
Radius of the radiation isocenter.
Output / Detected beams:
Number of detected beams.
Output / Distance fiducial-isocenter:
Distance between fiducial and radiation isocenter.
Results
Results
Step 6:
Click on Report to get the results in a PDF file.
Troubleshooting 1:
The axes of the star have higher values than the background. Click on the Complement button to calculate the complementary image.
Starshot: error
Starshot: error
Troubleshooting 2:
The cursor is far from the center of the star. Lock the cursor in a position closer to the isocenter.
Troubleshooting 3:
Excessive noise, large beam widths, beams too close to each other, image artifacts, etc., can induce errors in the location of the beams.
MLC Picket Fence

Check the accuracy of MLC positions with the Picket Fence test.

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 .
Step 4:
Introduce the inputs of the test.
Picket fence: input
Picket fence: input
Input / MLC:
Select the MLC model.
Input / Auto-correct Translation:
Automatically remove any small offset of the isocenter position on the x-axis. (Default: checked)
Input / Auto-correct Rotation:
Remove any small rotation of the beam lines. (Default: checked)
Input / Isocenter:
Introduce the position of the isocenter on the X-axis either manually or by locking the cursor near the center of the MLC on the X-axis. Use this field to introduce EPID offsets with respect to the isocenter.
Input / Distance scaling:
Introduce distance scaling (i.e., Source to Imager Distance / Source to Axis Distance). (Default: 1.0)
Input / Tolerance:
Tolerance for errors of leaf positions. (Default: 0.5 mm)
Input / 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). (Default: 50 %)
Input / ROI (optional):
Delineate the ROI (i.e., the MLC region).
MLC ROI
MLC ROI
Step 5:
Click on Calculate. Results will show after few seconds.
Picket fence: output
Picket fence: output
Output / Passing rate:
Percentage of leaf positions within tolerance.
Output / Mean absolute error:
Mean absolute leaf position error.
Output / Maximum absolute error:
Maximum absolute leaf position error.
Picket fence: results
Picket fence: results
Step 6:
Click on Report to get the results in a PDF file.
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 to calculate the complementary image.
Light and radiation field coincidence

Verify the coincidence of light and radiation field.

Step 1:
Load an image of a light-radiation test.
Light-radiation image
Light-radiation image
Step 2:
Click on the Light-radiation icon .
Step 3:
Introduce the inputs of the test.
Light-radiation: input
Light-radiation: input
Input / Field definition:
Select between Inflection points and FWHM. The FWHM follows the standard definition of radiation field as delimited by the 50% isodose of the beam profile. However, this definition requires that films are converted into dose distributions. When working with pixel values, an approximation to the radiation field can be obtained by the inflection points of the profiles.
Input / Nominal field size:
Introduce the nominal dimensions of the field on each semiaxis.
System of coordinates for QA tests
System of coordinates for QA tests
Input / Light points:
Introduce the points that mark the limits of the light field on each semiaxis. Enable them in Inputs and place them on the canvas. Light points shall correspond to the correct semiaxis and be located on the crosshair.
Input / ROI:
Select a ROI that encompasses the radiation field.
Light-radiation: canvas
Light-radiation: canvas
Step 4:
Click on Calculate. Results will show after few seconds.
Light-radiation: output
Light-radiation: output
Output / Light-radiation angle:
Rotation between light and radiation field.
Output / Light-radiation displacement:
Distance between radiation and light field. It is positive/negative when the radiation field is larger/smaller than the light field.
Output / Crosshair-light distance:
Light field dimensions on each semiaxis.
Output / CAX coordinates:
For symmetric nominal field sizes only: central axis coordinates of the radiation field.
Output / CAX distance to crosshair:
For symmetric nominal field sizes only: distance between the crosshair and the central axis.
Light-radiation: results
Light-radiation: results
Step 5:
Click on Report to get the results in a PDF file.
Troubleshooting 1:
The light points shall correspond to the correct semiaxis and be located on the crosshair.
Troubleshooting 2:
The ROI shall encompass the radiation field, not extend beyond the image, and avoid labels and other artifacts.
This test uses evolutionary algorithms to recognize the radiation field. Repeated calculations can deliver slightly different results because of the random nature of evolutionary algorithms.
Radiation field

Analysis of the radiation field, including field size, central dose statistics, flatness, symmetry, penumbra, etc.

It can analyze rectangular and circular fields (e.g., cones) of WFF photons, FFF photons, and electron beams.

It is the QA test of choice for also measuring small fields and output factors.

Available protocols for flatness and symmetry:

Photons WFF:
Photons FFF:
Electrons:

Step 1:
Load an image with a dose distribution of a rectangular or circular radiation field.
Radiation field image
Radiation field image
Step 2:
Click on the Radiation field icon .
Step 3:
Introduce the inputs of the test.
Radiation field: input
Radiation field: input
Input / Protocol for flatness and symmetry:
If you want to calculate flatness and symmetry, select one of the available protocols.
Input / Field geometry:
Select between rectangular and circular field.
Input / Apply field rotation:
Apply rotations while recognizing the rotation field. Do not apply rotations on fields with circular symmetry (e.g., cones and very small fields). (Default: checked)
Input / Central dose diameter:
Central dose statistics are measured for a circle with this diameter centered on the field. (Default: 1.0 mm)
Input / Averaging area:
Side of the area that averages pixel values for flatness and symmetry calculations. (Default: 10 mm)
Input / Field definition isodose:
Isodose that delimits the radiation field. (Default: 50%)
Input / Nominal field size:
Nominal field size dimensions.
Input / Crosshair coordinates (optional):
Lock the cursor and align it with the crosshair if the crosshair is marked on the image.
Input / ROI (optional/mandatory):
Select a ROI that encompasses the radiation field. This input is mandatory when applying the FFF AERB protocol.
Step 4:
Click on Calculate. Results will show after few seconds.
Radiation field: output
Radiation field: output
Output / Radiation field center:
Coordinates of the center of the radiation field.
Output / Radiation field size:
Dimensions of the radiation field.
Output / Radiation field rotation:
Rotation of the radiation field.
Output / Central dose statistics:
Statistics of the distribution of values within the central dose diameter.
Output / CAX distance to crosshair:
If the crosshair is introduced: distance between the crosshair and the central axis.
Output / Penumbras:
For rectangular fields except for FFF Elekta™ and FFF Varian™: distance between the 80-20% isodoses on each semiaxis.
Output / Flatness and Symmetry:
According to the different protocols, the outputs for flatness and symmetry are:
Photons WFF IEC / Elekta™:
Flatness
Symmetry
Maximum ratio of absorbed dose
Photons WFF TG45 / Varian™:
Flatness in the X and Y axes and both diagonals.
Symmetry in the X and Y axes and both diagonals.
Photons FFF Elekta™:
Symmetry
Isodose values on each semiaxis at different distances from the CAX.
Photons FFF Varian™:
Flatness
Symmetry
Isodose values on each semiaxis at different distances from the CAX.
Distances from the CAX to different isodoses on each semiaxis.
Photons FFF AERB of India:
Symmetry
Distances from the CAX to different isodoses on each semiaxis.
Electrons IEC / Elekta™:
Flatness: distance between the 90% isodose and the edge on each semiaxis and the diagonals.
Symmetry
Maximum ratio of absorbed dose
Electrons WFF TG45 / Varian™:
Flatness in the X and Y axes and both diagonals.
Symmetry in the X and Y axes and both diagonals.
Radiation field: results
Radiation field: results
Step 5:
Click on Report to get the results in a PDF file.
Troubleshooting 1:
The image must contain a dose distribution. If the image is a film scan, pixel values should be converted into doses.
Troubleshooting 2:
Rotation recognition may fail if the field has circular symmetry.
Troubleshooting 3:
The sample of central dose pixels may be empty if the central dose diameter is too small. As a consequence, the program will return an error.
This test uses evolutionary algorithms to recognize the radiation field. Repeated calculations can deliver slightly different results because of the random nature of evolutionary algorithms.
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