Synthetic Spine SABR Planning
30 Gy in 3 fractions·contributed by Orca Image·2026-08-27
This CT was generated by a model. No patient was scanned.
The anatomy is synthetic and the structures come from the generator rather than from a clinician. Treat the Hounsfield units as plausible rather than measured: there is no scanner behind them and so no CT-to-density calibration of yours applies, and because the image has no real counterpart the error in them cannot be quantified at all. It is a planning exercise, and every plan here is scored against the same geometry — but nothing learned from this case is a statement about a real patient.
- 1
Get the case
A de-identified CT and structure set, as one archive. Plan it in your own system.
No archive attached yet. - 2
Plan it
The criteria are published before anyone plans and do not change mid-challenge. Below they are also written as entries for your own optimizer.
- 3
Submit the dose
Upload the RTDOSE. It is scored automatically against the criteria, and you are told when it lands.
Guideline
The rules that decide whether a plan counts, before the numbers that score it.
Maximise target coverage while strictly respecting the neural constraints. The neural limits disqualify; everything else is scored.
Based on KROG 13-16, Spine SBRT for metastatic epidural spinal cord compression (multicentre prospective phase II). Dose ranges, neural and abdominal constraints, and the unacceptable-plan criteria are taken from it.
Where the points are
100 points published. The scoring criteria below are what this platform computes automatically.
Allowed
- Optimisation structures
- Rings, PRVs, target-minus-organ — build whatever your system needs. Scoring reads the published contours, never yours
- Modality
- Photon only
- Treatment unit
- Linac-based — C-arm, Halcyon, TomoTherapy
- Energy
- Any clinically commissioned photon energy
- Technique
- VMAT, IMRT, SRS/SBRT arc, or helical
- Dose calculation
- Heterogeneity-corrected algorithm
- Dose grid
- ≤ 1.5 mm recommended, 2.0 mm maximum
- Normalisation
- Free, provided the prescription and DVH reporting stay consistent
Not allowed
- Modality
- Proton, particle, electron, brachytherapy
- Contours
- Editing the provided GTV, PTV or OAR contours
- Deliverability
- Plans that could not be delivered clinically
- Density override
- Unless explicitly permitted
- Bolus
- Unless explicitly permitted
What disqualifies a plan
A fail removes the plan from the ranking whatever it scored. Some of these are checked from the dose automatically; an edited contour or an undeliverable plan is not, and is enforced by review.
- failNon-photon or non-linac plan
- failPrescription other than 30 Gy in 3 fractions
- failParticipant-edited GTV, PTV or OAR contours
- failMandatory neural constraint exceeded
- failPTV V30Gy < 80%
- failGTV V30Gy < 95%
- failNon-deliverable plan
- majorDose grid larger than 2.0 mm
- majorHot spot outside the target
- majorAny serial OAR mandatory D0.03cc exceeded
What to submit
- requiredRTDOSE
- recommendedRTPLAN
- recommendedDVH report
- recommendedAxial / sagittal / coronal isodose screenshots
- optionalPatient-specific QA result
Worth knowing before you start
- Deliverability — monitor units, modulation and treatment time — is 15 of the published 100 points and is not scored automatically. RTPLAN uploads make the MU part measurable; the rest is assigned by review after the deadline, as the original challenge did.
- The source document marks GTV V30Gy < 95% as 'major violation or fail'. It is enforced here as a fail, which is how the original challenge ran it. A plan at 94.9% is disqualified — worth knowing before spending the run on an organ at risk.
- The guideline recommends ranking conformity and gradient by percentile among valid submissions rather than fixed thresholds, because both are sensitive to target size and level. Fixed goals are used here so a plan can be scored on arrival; the percentile view belongs on the leaderboard, not in the score.
- Where the guideline writes '≤ 22 → 20' it is recording a revision. The later figure is used.
Scoring criteria
85 pointsHow a number becomes points. A metric at or past Ideal earns its full points. At the Minimum it earns none, and between the two it is linear — halfway between minimum and ideal is half the points. Worse than the minimum is zero for that line, never negative, and the rest of the plan still scores. Breaching a hard constraint is different: the plan keeps its number and leaves the ranking. How scoring works in full →
Target
| Metric | Minimum | Ideal | Points |
|---|---|---|---|
| GTV V30Gy | ≥ 95 | ≥ 98 | 10 |
| PTV V30Gy | ≥ 90 | ≥ 95 | 8 |
| PTV D95% | ≥ 27 | ≥ 30 | 7 |
| PTV D90% | ≥ 27 | ≥ 30 | 5 |
| PTV Dmax | ≤ 115 | ≤ 105 | 5 |
Organs at risk
| Metric | Minimum | Ideal | Points |
|---|---|---|---|
| Cauda equina D0.03ccon CaudaEquina | ≤ 24 | ≤ 20 | 12 |
| Cauda equina D0.35ccon CaudaEquina | ≤ 22 | ≤ 18 | 6 |
| Cauda equina D10%on CaudaEquina | ≤ 22 | ≤ 18 | 5 |
Organs at risk — sparing factor
Each group starts at its weight and gains a point per Gy spared below the ideal, so sparing further keeps paying off.
- Bowel, stomach and duodenum6 pts
d0.03cc ≤ 24, d5cc ≤ 14.5, d0.03cc ≤ 22, d20cc ≤ 18
- Kidney3 pts
d200cc ≤ 12, d200cc ≤ 12
- Skin and other3 pts
d0.03cc ≤ 22, d10cc ≤ 20, max_dose ≤ 24
Plan quality
| Metric | Minimum | Ideal | Points |
|---|---|---|---|
| CIon PTV | ≤ 1.2 | ≤ 1.05 | 5 |
| HIon PTV | ≤ 0.4 | ≤ 0.25 | 5 |
| GIon PTV | ≤ 6 | ≤ 3 | 5 |
Hard constraints
Breaching any of these removes the plan from the ranking, whatever it scored.
- Cauda equina D0.03cc > 24 Gy (mandatory neural constraint)
- Cauda equina D0.35cc > 22 Gy (mandatory neural constraint)
- PTV V30Gy < 80%
- GTV V30Gy < 95%
Spine SABR Plan Challenge Guideline (v2), adapted from KROG 13-16 by AOCMP 2026 Plan Challenge education committee.