RecoilEffectChecker

URS & FS — User Requirements and Functional Specification

This document describes the controlled interface and behaviour of RecoilEffectChecker for Recoil Effect.

Domain limits and critical parameters

• • Assessment of free daughter nuclide percentage
• ⚠️ CRITICAL: Recoil energy (~100+ keV) ALWAYS exceeds chemical bond energy (~few eV).
• BatchNumber,ParentIsotope,DaughterIsotope,AlphaEnergyMeV,BondEnergyKcalPerMol,ChelatorStabilityConstant,FreeDaughterPercent,RenalUptakeSUV,TimePostLabelingHours,ProductType
• • GeneratorEluate — generator eluates (control of parent breakthrough)
• • Result: Chemical bond BREAKS in 100% of cases. The daughter isotope (e.g., Fr-221 from Ac-225 or Bi-213 from Ac-225 chain) becomes a free ion.
• • Danger: Free daughter isotopes (especially Bi-213, Pb-212, Ra-223) accumulate in kidneys, causing acute radiation nephropathy.
• ⚠️ CRITICAL:
• • Control of Free Daughter Percent is the main safety parameter.
• • Prediction of nephrotoxicity based on free daughter levels
• Critical parameters:
• • Free Daughter Nuclide: ≤5.0% (Target for nanocarriers)
• • Renal Uptake (SUV): ≤10.0 (Safety threshold)
• • Time Post-Labeling: Dynamic monitoring (accumulation of free isotopes grows over time)
• ⚠️ Note: Recoil effect is a fundamental physical limitation of alpha therapy with small molecules. Transition to nanoparticles and liposomes is the main way to solve kidney toxicity problems.

URS — User Requirements Specification

input.csv contract

BatchNumber,ParentIsotope,DaughterIsotope,AlphaEnergyMeV,BondEnergyKcalPerMol,ChelatorStabilityConstant,FreeDaughterPercent,RenalUptakeSUV,TimePostLabelingHours,ProductType
AC225-PSMA-2026-001,Ac-225,Fr-221,5.83,80.0,25.0,15.0,25.0,24.0,TargetedAlphaTherapy
AT211-MAB-2026-002,At-211,Po-211,5.87,65.0,0.0,2.0,8.0,4.0,TargetedAlphaTherapy
BI213-DOTATATE-003,Bi-213,Tl-209,5.87,85.0,22.0,8.0,12.0,1.0,TargetedAlphaTherapy

FS — Functional Specification

Example output.json

{
  "utilityId": "recoil-effect-checker",
  "api": "Recoil Effect",
  "overallStatus": "PASS|WARNING|FAIL",
  "sourceFile": "input.csv",
  "checks": [
    {
      "parameter": "BatchNumber",
      "value": "AC225-PSMA-2026-001",
      "status": "PASS|WARNING|FAIL",
      "message": "Rule-based check result"
    },
    {
      "parameter": "ParentIsotope",
      "value": "Ac-225",
      "status": "PASS|WARNING|FAIL",
      "message": "Rule-based check result"
    },
    {
      "parameter": "DaughterIsotope",
      "value": "Fr-221",
      "status": "PASS|WARNING|FAIL",
      "message": "Rule-based check result"
    },
    {
      "parameter": "AlphaEnergyMeV",
      "value": "5.83",
      "status": "PASS|WARNING|FAIL",
      "message": "Rule-based check result"
    },
    {
      "parameter": "BondEnergyKcalPerMol",
      "value": "80.0",
      "status": "PASS|WARNING|FAIL",
      "message": "Rule-based check result"
    },
    {
      "parameter": "ChelatorStabilityConstant",
      "value": "25.0",
      "status": "PASS|WARNING|FAIL",
      "message": "Rule-based check result"
    },
    {
      "parameter": "FreeDaughterPercent",
      "value": "15.0",
      "status": "PASS|WARNING|FAIL",
      "message": "Rule-based check result"
    },
    {
      "parameter": "RenalUptakeSUV",
      "value": "25.0",
      "status": "PASS|WARNING|FAIL",
      "message": "Rule-based check result"
    }
  ],
  "criticalFindings": []
}

OQ/PQ test scenarios

QA/QC and change control

• Do not rename columns without updating the validator and test set.
• Retain input.csv, output.json, executable version and checksum.
• Before production use, perform IQ/OQ/PQ or equivalent CSV/CSA verification.
• Critical radiopharmaceutical limits must be verified against the approved specification and local SOPs.