SmallFieldCorrectionChecker

Small Field Correction

activity brachytherapy dosimetry source calibration TG-43

Small Field Correction Checker — Small Field Correction Verification (IAEA TRS-483)

ℹ️  The utility verifies correctness of applied detector correction factors ($k_{Q_{clin},Q_{msr}}^{f_{clin},f_{msr}}$) for small fields (SRS, SBRT) by comparing with reference data (IAEA TRS-483).
ℹ️  Critical for fields < 2×2 cm where detector volume averaging and density effects cause significant measurement errors.
ℹ️  Processing: only the FIRST record in input.csv file.
⚠️  Critical for safety! A 5% error in correction factor for 1 cm field leads to direct 5% dose error to patient, unacceptable in stereotaxy.

Usage:
  SmallFieldCorrectionChecker.exe                            → demo mode
  SmallFieldCorrectionChecker.exe input.csv output.json      → check data (first record only)

Input format:
PatientID,FieldName,FieldSizeCm,DetectorType,MeasuredOutputFactor,AppliedCorrectionFactor,ReferenceCorrectionFactor

Example (1.0 cm field, diode detector):
PT-2026-BRAIN-SRS,SRS_Cone_10mm,1.0,Diode_E,0.780,0.920,0.965

— WHY IS THIS NEEDED?
In small field dosimetry, standard detectors underestimate signal due to volume averaging and material density.
• Correction factors from protocols (TRS-483) must be applied.
• Physicist might err by selecting factor for wrong field size or detector type.
• Utility automatically compares entered value with reference and identifies discrepancies.
• Allows catching error before plan approval.
⚠️ CRITICAL:
• Tolerance on deviation: ≤ 1.5% (Warning), > 3.0% (Fail).
• For fields < 1 cm requirements are even stricter.
• Cannot use factor 1.0 for fields < 2 cm (unless special detector).
• TRS-483 tables must be up-to-date.
Critical parameters:
• Field size: < 2.0 cm (correction zone)
• Factor deviation: > 3% — critical error
• Detector type: Diodes, Diamonds, Ion chambers require different corrections
⚠️ Note: Utility flags cases where factor 1.0 is used for small field. Result includes status (PASS/WARNING/FAIL) and bilingual recommendation (RU/EN).

input.csv

PatientID,FieldName,FieldSizeCm,DetectorType,MeasuredOutputFactor,AppliedCorrectionFactor,ReferenceCorrectionFactor
PT-2026-BRAIN-SRS,SRS_Cone_10mm,1.0,Diode_E,0.780,0.920,0.965

URS & FS — user requirements and functional specification

This document defines user requirements and functional specification for the quality-control utility. It supports deployment discussion, IQ/OQ preparation and QC workflow integration.

Utility: SmallFieldCorrectionCheckerAPI / object: Small Field CorrectionCategory: Radiation physics

1. Scope

The Small Field Correction Checker utility is used for Small Field Correction. The actual input.csv is the source of truth for the input structure; control criteria are defined by the executable and the domain description.

The utility does not use machine learning; decisions are produced by deterministic rules.

Categories: Radiation physics

Tags: activity, brachytherapy, dosimetry, source calibration, TG-43

2. Execution modes

SmallFieldCorrectionChecker.exe                            → demo mode
SmallFieldCorrectionChecker.exe input.csv output.json      → check data (first record only)

3. Key controlled areas

pH and physicochemical parameters
activity, decay and radiochemical purity

4. Domain limits and critical parameters

⚠️ Critical for safety! A 5% error in correction factor for 1 cm field leads to direct 5% dose error to patient, unacceptable in stereotaxy.
⚠️ CRITICAL:
Tolerance on deviation: ≤ 1.5% (Warning), > 3.0% (Fail).
For fields < 1 cm requirements are even stricter.
Cannot use factor 1.0 for fields < 2 cm (unless special detector).
TRS-483 tables must be up-to-date.
Critical parameters:
Field size: < 2.0 cm (correction zone)
Factor deviation: > 3% — critical error
Detector type: Diodes, Diamonds, Ion chambers require different corrections
⚠️ Note: Utility flags cases where factor 1.0 is used for small field. Result includes status (PASS/WARNING/FAIL) and bilingual recommendation (RU/EN).

Limits stated in the description must be verified against the current approved specification, pharmacopoeial monograph and registration dossier before production use.

5. URS — user requirements

ID	Requirement	Criticality	Acceptance criterion
URS-001	The system shall accept an `input.csv` file for Small Field Correction with the exact columns listed in the “Input data contract” section.	High	A file with the correct header is processed without manual editing; missing mandatory columns produce FAIL/import error.
URS-002	The system shall support execution without arguments in demo mode and execution with `input.csv output.json` for user data.	Medium	Both execution scenarios produce a predictable result or clear diagnostic error.
URS-003	The system shall perform rule-based controls for: pH and physicochemical parameters, activity, decay and radiochemical purity.	High	Each controlled parameter receives a status and message; the result does not depend on hidden Excel formulas or ML.
URS-004	The system shall preserve traceability between batch/lot, source values, applied rules and final verdict.	High	Output includes batch identifier, source values, parameter statuses and critical findings.
URS-005	The system shall generate machine-readable `output.json` for LIMS/ELN/MES, batch record and QA/QC review.	High	JSON contains overall status, check array, warnings, failures and source-file reference.
URS-006	The system shall support use in the client validation package: URS/FS, IQ/OQ preparation, installation and operational scenario checks.	High	The document, test scenarios and reproducible CSV/JSON flow are suitable for audit and internal approval.
URS-007	The system shall clearly separate technical data errors from specification nonconformities.	Medium	Schema/type errors are not mixed with pharmacopoeial deviations and are reported separately.

6. input.csv data contract

The source of truth for the input schema is the actual input.csv header. Column names are technical identifiers and are not translated.

#	Column	Type	Unit	Description	Sample	Control rule
1	`PatientID`	text	as specified	Patient ID	`PT-2026-BRAIN-SRS`	mandatory value; format and acceptability are checked by the utility
2	`FieldName`	text	as specified	Field Name	`SRS_Cone_10mm`	mandatory value; format and acceptability are checked by the utility
3	`FieldSizeCm`	decimal	as specified	Field Size Cm	`1.0`	mandatory numeric value; rule comparison is performed by the utility
4	`DetectorType`	text	as specified	Detector Type	`Diode_E`	mandatory value; format and acceptability are checked by the utility
5	`MeasuredOutputFactor`	decimal	as specified	Measured Output Factor	`0.780`	mandatory numeric value; rule comparison is performed by the utility
6	`AppliedCorrectionFactor`	decimal	as specified	Applied Correction Factor	`0.920`	mandatory numeric value; rule comparison is performed by the utility
7	`ReferenceCorrectionFactor`	decimal	as specified	Reference Correction Factor	`0.965`	mandatory numeric value; rule comparison is performed by the utility

CSV example

PatientID,FieldName,FieldSizeCm,DetectorType,MeasuredOutputFactor,AppliedCorrectionFactor,ReferenceCorrectionFactor
PT-2026-BRAIN-SRS,SRS_Cone_10mm,1.0,Diode_E,0.780,0.920,0.965

7. FS — functional specification

ID	Function	Implementation description
FS-001	CLI entry point	The executable `SmallFieldCorrectionChecker.exe` supports demo mode and `input.csv output.json` processing mode.
FS-002	CSV parser	The import module reads CSV, validates header, column presence/order, value count and encoding. Decimal values are expected with a dot separator.
FS-003	Field conversion	Each column is converted to the expected type: identifier, text, decimal number, date/time or boolean flag.
FS-004	Domain rule engine	For Small Field Correction, explicit rules are applied: range, minimum, maximum, absence of prohibited flag, data completeness or calculation-based check.
FS-005	Criticality handling	Critical violations produce FAIL; non-critical deviations and incomplete data produce WARNING; full conformance produces PASS.
FS-006	JSON writer	`output.json` stores overall status, per-parameter results, source values, warnings, failures and diagnostic messages.
FS-007	Integration contract	The CSV → JSON format is stable for invocation from LIMS/ELN/MES, scheduled task or wrapper service.
FS-008	Error handling	Schema error, missing file, non-numeric value or JSON write failure returns diagnosable error without silent PASS.

8. output.json contract

The output file must be suitable for automated processing, audit review and correlation with the source input.csv row.

{
  "utility": "SmallFieldCorrectionChecker",
  "api": "Small Field Correction",
  "batchNumber": "",
  "overallStatus": "PASS|WARNING|FAIL",
  "checkedAtUtc": "2026-05-18T00:00:00Z",
  "checks": [
    {
      "parameter": "PatientID",
      "value": "PT-2026-BRAIN-SRS",
      "unit": "as specified",
      "status": "PASS|WARNING|FAIL",
      "message": "Rule-based check result"
    },
    {
      "parameter": "FieldName",
      "value": "SRS_Cone_10mm",
      "unit": "as specified",
      "status": "PASS|WARNING|FAIL",
      "message": "Rule-based check result"
    },
    {
      "parameter": "FieldSizeCm",
      "value": "1.0",
      "unit": "as specified",
      "status": "PASS|WARNING|FAIL",
      "message": "Rule-based check result"
    },
    {
      "parameter": "DetectorType",
      "value": "Diode_E",
      "unit": "as specified",
      "status": "PASS|WARNING|FAIL",
      "message": "Rule-based check result"
    },
    {
      "parameter": "MeasuredOutputFactor",
      "value": "0.780",
      "unit": "as specified",
      "status": "PASS|WARNING|FAIL",
      "message": "Rule-based check result"
    },
    {
      "parameter": "AppliedCorrectionFactor",
      "value": "0.920",
      "unit": "as specified",
      "status": "PASS|WARNING|FAIL",
      "message": "Rule-based check result"
    },
    {
      "parameter": "ReferenceCorrectionFactor",
      "value": "0.965",
      "unit": "as specified",
      "status": "PASS|WARNING|FAIL",
      "message": "Rule-based check result"
    }
  ],
  "criticalFindings": [],
  "sourceFile": "input.csv"
}

9. OQ/PQ test scenarios

ID	Scenario	Expected result
TC-001	Valid CSV with expected header and sample row	All rows are processed; output contains PASS/WARNING/FAIL and parameter-level detail.
TC-002	A mandatory input.csv column is missing	Import is rejected or the row receives FAIL with schema reference.
TC-003	A numeric field contains text or a blank value	Type conversion error is recorded; the result is not hidden as PASS.
TC-004	A parameter is outside specification or critical limit	Critical parameters produce FAIL; non-critical deviations produce WARNING according to the rule.

10. QA/QC, CSV and change control

Before production use, the client records executable version, checksum, specification/monograph version, test CSV, expected JSON and IQ/OQ results.
Column names must not be changed without updating the validator and test scenarios.
The source CSV, output.json and utility version should be stored together as an evidence package.
Any change in control rules must go through change control and repeated OQ scenario verification.

Included in packages

Radiation Physics QC Suite

Utilities for activity, dosimetry, brachytherapy sources, small-field corrections and TG-43 parameters.

Open

RPH organ/system: brain and CNS

Brain perfusion, dopamine transporter, amyloid/tau, receptor imaging and neurological SPECT/PET.

Open

RPH use case: PET scanner state, gamma camera and radiation physics

The linked medical-device/radiation-physics layer: PET detector QC, normalization, AC map, cross-calibration, TOF, gamma-camera uniformity, source strength and staff dose.

Open

RPH workflow: dosimetry and therapy planning

Activity planning, absorbed dose, organ dose, lung shunt, preplanning and therapy verification.

Open

RPH workflow: instruments, devices and radiation safety

PET/gamma-camera state, calibration, detector QC, energy window, TOF, shielding and radiation safety.

Open