Cancer retreatment


Learn how to use this tool with step-by-step instructions.

Watch the Video Tutorial

We have created a comprehensive video tutorial for use of the CR Design Platform.

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    Step 1: Simulation
    Conduct a new simulation scan and import the images into your preferred treatment planning software.
  • 2
    Step 2: Records
    Acquire the records from the first round of radiation ideally this will encompass isodose lines and structures from the initial treatment. If available, import these into your treatment planning software.
  • 3
    Step 3: Image Fusion
    Perform an image fusion of the original simulation scan to superimpose and adjust prior structures and isodose lines onto the new simulation scan.
  • 4
    Step 4: Contouring
    Visually inspect anatomical landmarks where previous radiation was applied you can use Boolean logic and contour organs at risk that received certain levels of dose especially high dose areas.
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    Step 5: Navigate to Cancer Retreatment
    Go to and proceed to the ReRT Calc. By default, you will be directed to our custom re-irradiation calculator with logic shown below. If you prefer a time-based discount re-irradiation calculator, we have also created a separate calculator accessible by clicking the clock icon in the top menu of the ReRT calc that uses logic from Paradis KC et al. PMID: 31681862
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    Step 6: Calculator inputs (Initial Treatment)
    Input initial radiation treatment course including dose and fractionation. By default, the Alpha Beta ratio is set to 3 for normal tissues, but this can be adjusted according to the entire plan or on an organ-specific basis.
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    Step 7: Calculator inputs (Organs at Risk)
    Choose the Organs at Risk you want to evaluate by selecting preset options or using your own custom criteria. You can now select any OARs you want to evaluate by ticking the checkbox or clicking the organ name. The OARs and dosimetric values you use would be those for the OARs you have already contoured that overlap with the prior radiation. By default, the presets incorporate cumulative safe and borderline thresholds obtained from academic literature. You can click on the dosimetric value or reference icon to view the referenced literature for that constraint. Input the dose each OAR received from the initial course of radiation. Users use the dose received at the initial plan fractionation. Users do not need to calculate EQD2 as the calculator performs this calculation. This data may aid in determining if your current fractionation plan will be feasible. You also have the option to switch between EQD2 and BED values by clicking the relevant toggle button. Take note, you can also change the alpha beta ratio you’re using for each organ by clicking the checkbox and providing a new alpha beta ratio. You also have the choice to create your own unique constraints.
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    Step 8: Calculator inputs (New Course)
    Now, input the prescription you intend to treat the patient with, whether it’s 60Gy in 10, 70Gy in 35, or 50Gy in 4.
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    Step 9: Results
    In the final step, evaluate the safe and borderline values for metrics like Dmax, D2cc, V20Gy, and more that appear in the result section as the calculator considers the OARs’ cumulative threshold, the exposure from the first course, and your second course fractionation. The result offers remaining safe and borderline constraints that can be used during planning to ensure your case is as safe as possible. We provide several methods to facilitate communication of these metrics to other team members including print, share, and download functions, as shown here.

Fractionation Conversion between Initial Plan and Retreatment (Re-RT Calc Logic)

In order to be compared, the initial plan, reirradiation thresholds and retreatment dose must all be converted into BED. Once the initial plan has been converted into BED the residual BED can be calculated. It is important to note that many published reirradiation cumulative thresholds are given in EQD2, for the sake of simplicity the calculator also converts these values into BED.

The amount of BED received by a tissue in the initial treatment is subtracted from the cumulative BED threshold. The remaining BED above the threshold is then used in combination with the reirradiation fractionation to calculate the remaining dose that can be delivered. The remaining dose is then displayed in the fractionation scheme that has been entered for the reirradiation.

This remaining dose can then be used as a planning dose limit for the tissue of interest.

Defining features

Explore the distinct qualities that set us apart in cancer re-treatment


Building strong connections between patients, doctors, and care teams.


Continually advancing our treatment planning algorithm for optimal outcomes.


Offering a wide range of tools and resources for re-treatment planning.


Providing a supportive community for patients, families, and loved ones navigating re-treatment.


Ensuring information is readily available to everyone who needs it.


Equipping patients with the knowledge and resources to navigate their care.

Revolutionizing Cancer Re-treatment.

Your Journey Matters to Us

We are here to support you and answer any questions you may have about our platform, the re-treatment process, and available resources. Don’t hesitate to reach out.