{"schema":"https://ver.cy/schemas/card/1.0.0","id":"vr.tr.linear-energy-transfer","code":"thing-q1699996","url":"https://ver.cy/models/thing/q1699996/","name":"linear energy transfer","alternateNames":[],"kind":"thing","status":"published","version":"0.1.0-research.1","language":"en","classifiers":{"family":"Thing Registry","category":"Cross-cutting context","entryKind":"thing","plane":"XCT","domain":["XCT.QLT"],"industry":[],"navPath":"","tags":[],"facets":{}},"whatItIs":"Linear energy transfer (LET) is the mean energy lost by a charged particle through electronic interactions per unit path length in a specified material, with restricted LET excluding energy carried away by secondary electrons whose kinetic energies exceed a specified cutoff.","purpose":"Enable an agent to identify, compare and use linear energy transfer descriptions while preserving the particle, material, restriction and averaging conditions that give each value meaning.","scope":{"in":["Restricted and unrestricted LET definitions and their stated conventions","Dependence on charged-particle species, kinetic energy and traversed material","LET values, spectra and spatial distributions","Track-weighted and dose-weighted LET summaries","Measurement inference, calculation settings and uncertainty","Conditions for comparing LET or using it in radiation-effect models"],"out":["Complete models of particle beams, accelerators and irradiation facilities","Absorbed dose, equivalent dose and radiation protection quantities as independent concepts","Complete stopping-power and particle-range models","Microdosimetric lineal-energy and specific-energy distributions as independent quantities","Biological damage mechanisms and relative biological effectiveness models","Detector construction and clinical treatment prescriptions"],"boundaries":[]},"distinguishingFeatures":["A LET value describes energy transfer per charged-particle path length; it is not absorbed energy per unit mass.","Unrestricted LET corresponds numerically to electronic collision stopping power, rather than stopping power including every loss mechanism. [NIST stopping-power report](https://nvlpubs.nist.gov/nistpubs/Legacy/IR/nbsir82-2550A.pdf)","Restricted LET requires a declared secondary-electron energy cutoff and restriction convention; a bare number does not establish which quantity was reported.","Lineal energy uses single-event energy imparted to a finite site divided by its mean chord length; matching units do not make it LET. [Microdosimetry uncertainty study](https://doi.org/10.1088/1361-6560/AC79FB)","A beam-level average requires a weighting rule and included particle population; the label LET alone does not identify that average."],"structure":{"bundles":[{"id":"definition-and-restriction","name":"Definition and restriction","description":"Establish exactly which energy transfers and path-length convention define the reported LET.","layers":[{"id":"electronic-transfer-boundary","name":"Electronic transfer boundary","description":"Separate LET from total stopping power and finite-volume energy deposition.","findings":[{"id":"identify-defining-convention","name":"Identify defining convention","description":"Record the defining authority, edition and expression; unrestricted LET is numerically associated with collision stopping power. [NIST stopping-power report](https://nvlpubs.nist.gov/nistpubs/Legacy/IR/nbsir82-2550A.pdf)","questions":[{"text":"Which reference and mathematical definition establish the meaning of LET in this record?","id":"identify-defining-convention-q01","kind":"definition"},{"text":"Does the supplied quantity include radiative or nuclear losses that place it outside that LET definition?","id":"identify-defining-convention-q02","kind":"boundary"}]}]},{"id":"secondary-electron-restriction","name":"Secondary-electron restriction","description":"Make the cutoff and treatment of energetic secondary electrons explicit.","findings":[{"id":"resolve-cutoff-semantics","name":"Resolve cutoff semantics","description":"Record Δ and the exact rule for excluding energy associated with secondary electrons; verify equivalence before substituting a restricted stopping-power implementation. [ICRU Report 35](https://www.nist.gov/system/files/documents/calibrations/icru-35.pdf)","questions":[{"text":"What is Δ, and is the quantity restricted or explicitly unrestricted?","id":"resolve-cutoff-semantics-q01","kind":"measurement"},{"text":"Does the implementation restrict secondary-electron kinetic energy, total energy transfer or another specified contribution?","id":"resolve-cutoff-semantics-q02","kind":"definition"}]}]}]},{"id":"particle-and-medium-conditions","name":"Particle and medium conditions","description":"Identify the charged particles and material to which LET applies.","layers":[{"id":"charged-particle-state","name":"Charged-particle state","description":"Describe the species and energy at the relevant track location.","findings":[{"id":"bind-let-to-particle-state","name":"Bind LET to particle state","description":"Require the particle identity, local kinetic energy and any charge-state assumptions used in calculation.","questions":[{"text":"Which charged-particle species and local energy or energy spectrum does the LET describe?","id":"bind-let-to-particle-state-q01","kind":"measurement"},{"text":"For a photon or neutron field, which secondary charged particles supply the tracks represented by this LET?","id":"bind-let-to-particle-state-q02","kind":"boundary"}]}]},{"id":"material-and-normalization","name":"Material and normalization","description":"Keep actual material, reference material and density normalization distinguishable.","findings":[{"id":"establish-medium-basis","name":"Establish medium basis","description":"Record composition, density and any conversion to a reference material such as water.","questions":[{"text":"Is the value LET in the traversed material or a calculated LET in a reference material?","id":"establish-medium-basis-q01","kind":"definition"},{"text":"Is the reported quantity L or L/ρ, and which density and units support conversion?","id":"establish-medium-basis-q02","kind":"measurement"}]}]}]},{"id":"spectra-and-averaging","name":"Spectra and averaging","description":"Describe how a population of tracks becomes a LET distribution or summary.","layers":[{"id":"population-and-spatial-support","name":"Population and spatial support","description":"Identify included tracks and the region in which their contributions are collected.","findings":[{"id":"define-spectrum-support","name":"Define spectrum support","description":"Specify species inclusion, LET bins, spatial extent and normalization before interpreting a spectrum.","questions":[{"text":"Are primary particles, secondary electrons, recoil ions and nuclear fragments included or excluded?","id":"define-spectrum-support-q01","kind":"boundary"},{"text":"What location, voxel size, LET binning and normalization define the distribution?","id":"define-spectrum-support-q02","kind":"measurement"}]}]},{"id":"weighted-let-estimators","name":"Weighted LET estimators","description":"Make the averaging equation part of the quantity's identity.","findings":[{"id":"preserve-weighting-rule","name":"Preserve weighting rule","description":"Record track or dose weights, denominators and aggregation order; segment-based approaches also require explicit track-segment assumptions. [Segment-averaged LET research](https://aapm.onlinelibrary.wiley.com/doi/abs/10.1002/mp.13673)","questions":[{"text":"What exact numerator, denominator and weights define the reported average?","id":"preserve-weighting-rule-q01","kind":"definition"},{"text":"Can regional LET be recomputed from underlying weighted contributions rather than an unweighted average of voxel averages?","id":"preserve-weighting-rule-q02","kind":"action"}]}]}]},{"id":"estimation-and-verification","name":"Estimation and verification","description":"Connect LET estimates to the measurements, tables or transport calculations that produced them.","layers":[{"id":"calculation-and-detector-inference","name":"Calculation and detector inference","description":"Document the route from raw evidence to the reported quantity.","findings":[{"id":"trace-let-estimator","name":"Trace LET estimator","description":"Record the table or transport implementation, or the detector-response inversion, together with its material and energy applicability.","questions":[{"text":"Which dataset, software version, physics settings or detector calibration generated the estimate?","id":"trace-let-estimator-q01","kind":"provenance"},{"text":"If derived from deposited energy or lineal energy, what reconstruction makes the output an estimate of the declared LET?","id":"trace-let-estimator-q02","kind":"measurement"}]}]},{"id":"uncertainty-and-convergence","name":"Uncertainty and convergence","description":"Assess whether numerical choices and evidence limitations materially change the LET result.","findings":[{"id":"qualify-estimate-stability","name":"Qualify estimate stability","description":"Track sensitivity to transport thresholds, step lengths, scoring resolution, material inputs and sampling, distinguishing numerical settings from the physical LET cutoff.","questions":[{"text":"How does the estimate change when step limits, production thresholds, voxel size or sample count are varied?","id":"qualify-estimate-stability-q01","kind":"measurement"},{"text":"Which independent benchmark supports the stated uncertainty for this particle, medium and energy range?","id":"qualify-estimate-stability-q02","kind":"provenance"}]}]}]},{"id":"interpretation-and-use","name":"Interpretation and use","description":"Define which comparisons and downstream inferences a LET description supports.","layers":[{"id":"comparison-eligibility","name":"Comparison eligibility","description":"Check that values describe compatible quantities before ranking or combining them.","findings":[{"id":"establish-comparable-let","name":"Establish comparable LET","description":"Require compatible restriction, medium, particle inclusion, weighting and spatial support, or an explicit justified transformation.","questions":[{"text":"Which defining conditions differ between these LET results, and can those differences be reconciled?","id":"establish-comparable-let-q01","kind":"boundary"},{"text":"What application-specific threshold and reference population justify calling this LET high or low?","id":"establish-comparable-let-q02","kind":"definition"}]}]},{"id":"radiation-effect-linkage","name":"Radiation-effect linkage","description":"Link LET to effect models without treating it as a complete prediction of damage.","findings":[{"id":"bound-effect-inference","name":"Bound effect inference","description":"Record the endpoint and response model before using an average LET to infer biological effectiveness; the adequacy of dose-averaged LET depends on response assumptions. [RBE prediction study](https://aapm.onlinelibrary.wiley.com/doi/abs/10.1002/mp.13347)","questions":[{"text":"Which endpoint, particle types, dose conditions and biological system support this LET-to-effect relationship?","id":"bound-effect-inference-q01","kind":"boundary"},{"text":"Does the intended decision require a LET spectrum, track-structure information or other evidence beyond the reported average?","id":"bound-effect-inference-q02","kind":"action"}]}]}]},{"id":"evidence-and-external-alignment","name":"Evidence and external alignment","description":"What the world already says about this thing, gathered so the model can be checked against it.","layers":[{"id":"reported-evidence","name":"Reported evidence","description":"Findings from the breadth pass, kept separate from the structural claims.","findings":[{"id":"evidence-confidence-notes","name":"Check these first","description":"Recalled without web access and unsourced; every item is a lead to verify.","questions":[{"text":"Which of these check these first hold for the sense of linear energy transfer this model covers, and on what evidence?","id":"evidence-confidence-notes-q01","kind":"provenance"}]},{"id":"evidence-kinds","name":"Kinds and varieties","description":"Recalled without web access and unsourced; every item is a lead to verify.","questions":[{"text":"Which of these kinds and varieties hold for the sense of linear energy transfer this model covers, and on what evidence?","id":"evidence-kinds-q01","kind":"provenance"}]},{"id":"evidence-standards-and-regulation","name":"Standards and regulation","description":"Recalled without web access and unsourced; every item is a lead to verify.","questions":[{"text":"Which of these standards and regulation hold for the sense of linear energy transfer this model covers, and on what evidence?","id":"evidence-standards-and-regulation-q01","kind":"provenance"}]},{"id":"evidence-real-world-use","name":"Real-world use","description":"Recalled without web access and unsourced; every item is a lead to verify.","questions":[{"text":"Which of these real-world use hold for the sense of linear energy transfer this model covers, and on what evidence?","id":"evidence-real-world-use-q01","kind":"provenance"}]},{"id":"evidence-measurements","name":"Typical measurements","description":"Recalled without web access and unsourced; every item is a lead to verify.","questions":[{"text":"Which of these typical measurements hold for the sense of linear energy transfer this model covers, and on what evidence?","id":"evidence-measurements-q01","kind":"provenance"}]},{"id":"evidence-failure-modes-and-hazards","name":"Failure modes and hazards","description":"Recalled without web access and unsourced; every item is a lead to verify.","questions":[{"text":"Which of these failure modes and hazards hold for the sense of linear energy transfer this model covers, and on what evidence?","id":"evidence-failure-modes-and-hazards-q01","kind":"provenance"}]},{"id":"evidence-neighbours","name":"Neighbouring kinds and how to tell them apart","description":"Recalled without web access and unsourced; every item is a lead to verify.","questions":[{"text":"Which of these neighbouring kinds and how to tell them apart hold for the sense of linear energy transfer this model covers, and on what evidence?","id":"evidence-neighbours-q01","kind":"provenance"}]}]}]}]},"agentConduct":{"may":["Explain linear energy transfer and how it relates to biological effects of radiation.","Compute or look up LET values from stated particle, energy and material data."],"mustNot":["Give a person radiation dose or treatment advice in place of a medical physicist or clinician.","Present LET values without stating the particle, energy, material and any cut-off used.","Downplay or exaggerate radiation risk by misusing LET data.","Confuse LET with absorbed dose or stopping power in safety calculations."],"requiresHuman":["Decisions on radiotherapy plans or radiation protection that use the values."]},"ethics":{"considerations":["Radiation quality matters to patients and workers; errors can cause harm or needless fear."],"affectedParties":["Radiotherapy patients","Radiation workers","Astronauts and aircrew"]},"owners":{"steward":"Nobody owns it; radiation measurement bodies maintain its definition.","roles":[],"masterSystems":[]},"relations":[{"target":"Q107715","type":"parent","note":"registry parent class"}],"interaction":{"identity":{"applicability":"required","items":["Vercy registry: vr.tr.linear-energy-transfer","Wikidata: Q1699996 (https://www.wikidata.org/wiki/Q1699996)"]},"properties":{"applicability":"not-applicable","items":["LET magnitude: keV/µm or J/m, with uncertainty","Restriction convention: Restricted LΔ; unrestricted L∞; explicitly documented alternative; unspecified","Secondary-electron cutoff: eV or keV; infinity for unrestricted LET","Charged-particle population: Species and included primary, secondary and fragment populations","Particle kinetic energy: eV, keV or MeV; MeV/u explicitly distinguished","Reference material: Material identity, composition, density and relevant physical state","Averaging convention: Unaveraged conditioned value; track-weighted; dose-weighted; other explicit estimator","Spatial support: Track segment, depth interval, voxel or region with dimensions","Density normalization: Linear LET L; mass-normalized L/ρ","Evidence readiness: Convention incomplete; reproducible estimate; independently checked within a stated domain"]},"recognition":{"applicability":"optional","items":["Written as L or LET, usually in keV per micrometre."]},"capabilities":{"applicability":"required","items":["Check whether a reported LET value includes enough conditions to be interpreted.","Convert compatible units and density normalizations using a documented material density.","Calculate or retrieve LET for a specified particle, energy, medium and restriction.","Construct LET spectra and explicitly weighted summaries from suitable track or transport data.","Compare LET distributions after checking conventions, particle inclusion and spatial support.","Pass LET to a radiation-effect model only with its required context and applicability limits."]},"hazards":{"applicability":"required","items":["Mixing up restricted and unrestricted LET gives wrong risk estimates.","Errors in high-LET weighting can misstate biological harm."]},"interfaces":{"applicability":"required","items":["ICRU Report 85, Fundamental Quantities and Units for Ionizing Radiation, International Commission on Radiation Units and Measurements."]},"context":{"applicability":"required","items":["Linear energy transfer is used in radiation physics and radiobiology to describe energy loss along charged-particle tracks in a material.","It supports comparisons of radiation fields in particle therapy research, radiation protection and studies of material damage.","Meaningful comparisons require the material, particle characteristics, secondary-electron energy cutoff and averaging convention to be specified."]}},"sources":[{"title":"Wikidata item Q1699996: linear energy transfer","url":"https://www.wikidata.org/wiki/Q1699996","note":"identity and sense of the item"},{"title":"Wikipedia: Linear energy transfer","url":"https://en.wikipedia.org/wiki/Linear_energy_transfer","note":"general description of the item"}],"openQuestions":["Which authoritative definition and edition should anchor the registry entry, particularly where restricted LET and restricted stopping-power conventions differ?","Which particle species, media and energy ranges should receive validated operationalisations first?","Which averaging and secondary-particle inclusion conventions must be supported to make records interoperable across transport codes?","Under what detector geometries and reconstruction assumptions can measured signals provide a defensible estimate of the declared LET?","For each intended application, when is a scalar LET summary sufficient, and when must the model require spectra or microdosimetric information?"],"resources":{"spec":"/models/things/publications/thing-q1699996/spec.json"},"provenance":{"origin":"thing registry research (pass 2)","builtFrom":["models/things/publications/thing-q1699996/spec.json"],"providers":["Codex"],"researchStatus":"unreviewed","generatedAt":"2026-09-12T10:58:29Z","builder":"tools/build_cards.py@1.0.0"},"completeness":{"sections":{"classifiers":"filled","whatItIs":"filled","purpose":"filled","distinguishingFeatures":"filled","structure":"filled","agentConduct":"filled","ethics":"filled","owners":"filled","relations":"filled","interaction.identity":"filled","interaction.properties":"not-applicable","interaction.recognition":"filled","interaction.capabilities":"filled","interaction.hazards":"filled","interaction.interfaces":"filled","interaction.context":"filled","sources":"filled"},"notes":{"_gate":"Published through the thing publication gate 1.0 on 2026-10-07T10:10:26+00:00: completeness 1.00; sense: Wikidata description; 2 live sources; review by codex: pass","interaction.properties":"Plane XCT: no invented physical properties."},"score":1.0}}