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NCIRF User Manual

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NCI Dose Team edited this page May 12, 2026 · 27 revisions

NCIRF 4

NCI Dosimetry System for Radiography and Fluoroscopy

Current documented release: 4.20260510

NCIRF 4 main window overview

Introduction

The National Cancer Institute Dosimetry System for Radiography and Fluoroscopy (NCIRF) is a reference radiation dose estimation system developed by the National Cancer Institute (NCI) for estimating organ absorbed doses and effective dose associated with diagnostic radiography, fluoroscopy, and fluoroscopically guided interventional procedures.

NCIRF integrates computational human phantoms with a streamlined GEANT4 Monte Carlo radiation transport engine. Unlike NCICT and NCINM, which rely on pre-calculated dose conversion coefficients, NCIRF performs direct Monte Carlo radiation transport simulations based on user-specified imaging and geometric parameters.

NCIRF supports population-based dose evaluation, benchmarking, and retrospective dose reconstruction. It is not intended for real-time clinical decision support or site-specific clinical optimization.

Calculation Workflow

Step Description
1 Select the phantom library and patient characteristics
2 Define x-ray beam spectrum and dose quantity
3 Specify beam geometry, isocenter, and table thickness
4 Run GEANT4 Monte Carlo simulations
5 Review organ dose, error, PSD, and effective dose
6 Optionally run multiple cases through Batch Manager

1. Patient Characteristics

NCIRF 4 supports three phantom library categories:

  • Reference phantoms
  • Size-dependent phantoms
  • Pregnant phantoms

Reference Phantoms

Reference phantoms are available in three arm/posture libraries:

  • Arm raised reference phantom
  • Arm lowered reference phantom
  • Arm rotated reference phantom

Users select the reference phantom by choosing:

  • Arm posture
  • Age group
  • Sex

Reference height and weight are displayed automatically and are not editable. For ages that fall between reference groups, users may select the nearest reference age group or perform external interpolation as needed.

Reference phantom selection panel

Size-Dependent Phantoms

The size-dependent phantom library contains 362 phantoms:

  • Pediatric female
  • Pediatric male
  • Adult female
  • Adult male

Users select size-dependent phantoms by entering or adjusting:

  • Age group
  • Sex
  • Height (cm)
  • Weight (kg)

NCIRF 4 automatically matches the entered height and weight to the nearest available phantom grid point. Height and weight bins can be adjusted with the cursor up/down keys. Users may also select a phantom by clicking an available cell in the height-weight phantom map.

The height-weight phantom map displays available size-dependent phantoms as blue cells and highlights the currently selected phantom cell. Clicking an available cell updates the height and weight fields and refreshes the phantom views. Cells without an available phantom are ignored.

Selection of the correct pediatric/adult and sex group is important for active and shallow marrow dose calculations, because those calculations use age-dependent dose response functions.

Size-dependent phantom selection panel Size-dependent height-weight phantom map

Pregnant Phantoms

Pregnant phantoms are selected by gestational age. Available fetal ages are:

  • 8wk
  • 10wk
  • 15wk
  • 20wk
  • 25wk
  • 30wk
  • 35wk
  • 38wk

These phantoms include detailed fetal models for gestational-age dose evaluation.

When using pregnant phantoms, height and weight are not used.

Pregnant phantom selection panel

2. X-ray Beam Data

Users define the x-ray beam spectrum by selecting a kVp and half-value layer (HVL) combination. NCIRF 4 provides predefined kVp-HVL combinations.

Additional beam parameters include:

  • Source-to-isocenter distance (SID, cm)
  • Field width at isocenter (FW, cm)
  • Field height at isocenter (FH, cm)
  • Dose-area product (DAP, Gy-cm2)

DAP is required to scale Monte Carlo output to absolute absorbed organ dose. NCIRF 4 automatically selects the appropriate dose response function (DRF).

X-ray beam input panel

3. Beam Geometry

Beam orientation is defined using:

  • Practitioner Primary Angle (PPA)
  • Practitioner Secondary Angle (PSA)

Angles may be entered numerically, adjusted using cursor up/down keys, or selected using predefined beam directions. PSA supports a range of -90 to 90 degrees. NCIRF automatically adjusts PSA limits based on SID and phantom size.

NCIRF also checks the source position against the selected phantom bounding box. When SID, PPA, or PSA is edited, the program updates the allowed PPA/PSA range using the current SID, PPA/PSA combination, and phantom dimensions. If an entered angle would place the x-ray source inside the phantom box, NCIRF automatically clamps the angle to the nearest allowed value that keeps the source outside the phantom. The current allowed PPA and PSA ranges are displayed next to the angle inputs. SID is limited to a minimum of 30 cm.

Users also define:

  • Isocenter X, Y, and Z
  • Table thickness
Beam geometry and angle control panel

4. Phantom and Beam Geometry Views

The main GUI displays top, frontal, and lateral views of the selected phantom. These views show:

  • Isocenter position
  • Beam field box
  • Field width and height
  • X-ray source direction
  • Table position and thickness

The field box can be moved by mouse drag. Users may drag inside the field box or click and drag the field center directly.

In the top, frontal, and lateral phantom views, the field box can also be resized by dragging a box edge. The field center remains fixed during resizing: dragging the upper edge changes the lower edge symmetrically, and dragging the left or right edge changes the opposite edge symmetrically. The corresponding Field Width and Field Height input values are updated automatically. Because field width and height are defined on the beam-normal plane toward the source, the displayed resize behavior accounts for the current PPA and PSA projection.

Phantom picture resolution has been improved in NCIRF 4 for clearer visual feedback.

Phantom views with draggable field box

5. Monte Carlo Dose Calculation

Users specify:

  • Number of Monte Carlo histories
  • Thread count for multithreaded execution

GEANT4 simulations run in the background. NCIRF 4 includes:

  • MC calculation progress bar with percent display
  • Stop button for dose calculation
  • Faster backend calculation and UI update behavior

During the initial GEANT4 setup period, such as phantom and transport preparation before event progress text is available, the main GUI progress bar displays Preparing Monte Carlo.... After GEANT4 begins reporting transport progress, the progress bar switches to percent values such as 10%, 20%, and so on until the calculation reaches 100%.

Thread count should generally be selected based on available CPU cores and the desired balance between speed and system responsiveness.

Monte Carlo progress bar and stop button

6. Dose Output

After calculation, NCIRF reports:

  • Organ absorbed dose (mGy)
  • Monte Carlo statistical error (%)
  • Peak skin dose (PSD)
  • Effective dose (mSv)

Dose and error values are right-aligned in the main GUI table for easier scanning.

Effective dose is calculated using tissue weighting factors defined in ICRP Publication 103.

Main GUI dose and error output table

7. Batch Manager

NCIRF 4 uses a single unified Batch Manager for reference, size-dependent, and pregnant phantom calculations.

Unified Batch Manager window

Batch Manager Columns

Batch Manager uses compact headers:

Header Description
ID Patient identification number
PhtLib Phantom Library ID
Age Age in years, or gestational week for fetus such as 8wk
Sex f=female, m=male
HT Height in cm
WT Weight in kg
kVp X-ray energy kVp
HVL Half-value layer
SID Source-to-isocenter distance
FW Field width in cm
FH Field height in cm
DAP Dose-area product in Gy-cm2
PPA Practitioner primary angle
PSA Practitioner secondary angle
ISOX Isocenter X
ISOY Isocenter Y
ISOZ Isocenter Z
Tbl Table thickness in cm
Hist Monte Carlo particle history
Thread Thread number for hyperthreading
Run Check to run
Progress Batch calculation progress

Hovering over the Batch Manager header displays a more detailed tooltip for each column.

Phantom Library IDs

PhtLib Phantom library
1 Arm raised reference phantom
2 Arm lowered reference phantom
3 Arm rotated reference phantom
4 Size-dependent phantom
5 Pregnant phantom

Batch Input Rules

For reference phantoms (PhtLib 1, 2, or 3):

  • Age and Sex are used.
  • Age is automatically matched to the nearest supported reference age.
  • HT and WT are ignored and left blank in the Batch Manager.

For size-dependent phantoms (PhtLib 4):

  • Age, Sex, HT, and WT are used.
  • Pediatric/adult and female/male phantom group is derived from Age and Sex.
  • Pediatric is defined as age less than 20 years.
  • Height and weight are automatically matched to the nearest available size-dependent phantom.

For pregnant phantoms (PhtLib 5):

  • Age should use week notation, such as 8wk, 10wk, or 35wk.
  • Sex, HT, and WT are ignored and left blank in the Batch Manager.

Sex should be entered as f or m. CSV load also accepts F, M, and legacy numeric values 1 and 2.

Editing Batch Rows

Batch Manager cells can be edited directly. When a row value changes, NCIRF normalizes the phantom-related fields and reflects the selected row in the main GUI.

Stored dose and error results are cleared only when an editable input value actually changes. Clicking into a cell or selecting a row without changing the value does not reset the stored result or progress.

Examples:

  • Editing PhtLib, Age, or Sex updates the selected phantom.
  • Editing HT or WT for a size-dependent phantom snaps to the nearest phantom.
  • Editing reference or pregnant rows clears unused height and weight fields.

Sending Main GUI Settings to Batch Manager

The main GUI can send the current setup to Batch Manager.

If the main GUI does not contain a completed dose calculation result, NCIRF adds the row as input only and sets Progress to 0%.

If the main GUI contains a completed dose calculation result, NCIRF adds the row with Progress set to 100% and stores the current dose and error results in the Batch Manager background result arrays. The stored results are not displayed as extra visible Batch Manager cells, but they are available when the completed row is selected and are included when the batch file is saved.

Running Batch Calculations

Use the Run checkbox to select rows for calculation. Select All and Deselect All buttons are available for the Run checkboxes.

During batch calculation:

  • The active row progress is shown in the Progress column.
  • The main GUI progress bar displays Preparing Monte Carlo... while the active batch row is preparing GEANT4 transport.
  • After GEANT4 transport progress begins, the main GUI progress bar switches to percent values and the active batch row Progress column is updated.
  • Completed rows remain at 100%.
  • Dose and error results are stored internally.
  • When a completed row is selected, its stored dose and error results are shown in the main GUI.
  • While the next row is running, the previous completed dose and error values remain visible until the next result is ready.

Saving and Loading Batch CSV Files

Save Batch writes:

  • Input parameters
  • Completion progress
  • Dose result columns
  • Error result columns

Dose columns use the prefix Dose, such as:

  • Dose Brain
  • Dose Thyroid
  • Dose Effective dose mSv

Error columns use the prefix Error, such as:

  • Error Brain
  • Error Thyroid
  • Error Effective dose

Rows that have not completed are saved with 0% progress and blank result fields. Completed rows are saved with 100% progress and their stored dose and error result fields.

Load Batch restores input parameters into Batch Manager. If the CSV contains completed results, NCIRF loads those results internally and displays them in the main GUI when the completed row is selected.

Saved Batch CSV showing input and Progress columns

MCNP Input Generation

Batch Manager can generate MCNP input files for all supported phantom libraries:

  • Reference phantoms
  • Size-dependent phantoms
  • Pregnant phantoms

This is intended for external computing environments where MCNP input files are run outside the NCIRF GUI.

8. Notes and Limitations

  • NCIRF is intended for reference dose reconstruction and comparative analyses.
  • It is not intended for real-time clinical decision support.
  • Monte Carlo uncertainty depends on the number of particle histories.
  • Pregnant phantom calculations use gestational age rather than patient height and weight.
  • Batch result values are only available for rows that have completed calculation or have been loaded from a saved Batch CSV containing completed results.

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