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NCICT User Manual

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Choonsik Lee edited this page Jan 14, 2026 · 43 revisions

NCICT 3.0 — NCI Dosimetry System for Computed Tomography

NCICT overview

Introduction

The National Cancer Institute Dosimetry System for Computed Tomography (NCICT) is a reference-grade radiation dose estimation system developed at the National Cancer Institute (NCI) to estimate organ absorbed doses and effective dose for populations undergoing CT examinations.

NCICT is based on pre-calculated organ dose conversion coefficients derived from Monte Carlo radiation transport simulations, multiple computational human phantom models, and a reference CT scanner framework. The system is designed for population-based dose evaluation, benchmarking, and regulatory-facing analyses, rather than patient-specific clinical decision support.

Organ dose calculations follow four sequential steps:

  1. Patient characteristics
  2. Scanner parameters
  3. Scan coverage definition
  4. Organ and effective dose output

A Batch Calculation mode supports automated dose reconstruction for large datasets.

Intended use
NCICT is intended for reference dose estimation and comparative analyses.
It is not intended for real-time clinical dose calculation, site-specific customization, or individualized clinical decision making.

Calculation Workflow (Overview)

Step Description
1 Define patient age or body size
2 Specify scanner output (CTDIvol or reconstruction parameters)
3 Define scan coverage
4 Review organ and effective dose output

1. Patient Characteristics

NCICT supports two approaches depending on data availability.

Age-based selection

When detailed body size information is unavailable, users may select one of the ICRP-defined reference age groups:

  • Newborn
  • 1, 5, 10, or 15 years
  • Adult (assumed ≥20 years)

Reference height and weight are automatically assigned and are not editable.

If the patient age falls between groups, users may interpolate organ doses or select the nearest reference age.

View age-based selection example

Age-based selection

Height- and weight-based selection

When patient height and weight are available, users may directly specify body size within pediatric or adult phantom libraries.

This approach maps patient size to the closest matching body-size–dependent phantom.

View height–weight selection example

Height–weight selection

Pregnant patients and fetal dose

Separate tabs support fetal and maternal organ dose calculations for eight gestational ages.

View pregnancy tabs

Fetus tab Mother tab

2. Scanner Parameters

Two scenarios are supported.

CTDIvol available

Users enter CTDIvol, CTDI phantom type, and tube potential (kVp).

View CTDIvol input example

CTDIvol known

CTDIvol unavailable (reconstruction)

CTDIvol may be reconstructed using scanner model, kVp, mAs, pitch, and collimation.

View CTDIvol reconstruction example

CTDIvol reconstruction

Tube current modulation (TCM)

A vendor-neutral generic TCM model may be applied. Average CTDIvol is computed automatically.

View TCM settings

TCM settings

3. Scan Range Definition

Scan coverage may be defined interactively, numerically, or via predefined NIH protocols (e.g., head, chest, abdomen).

View scan range definition

Scan range definition

4. Dose Output

NCICT reports organ absorbed doses (mGy) and effective dose (mSv).
Results are suitable for comparative and population-level analyses, not individual risk estimation.

View dose output table

Dose output table

Batch Calculation Mode

Batch mode supports automated dose calculation from CSV input files when CTDIvol is available.

Access to NCI Dose Tools

Non-Commercial Research Use

Available at no charge under an approved Software Transfer Agreement (STA).

Contact:
Dr. Choonsik Lee
choonsik.lee@nih.gov

Commercial Use

Commercial use requires licensing through the NCI Technology Transfer Center.

Contact:
Dr. Kevin Chang
changke@mail.nih.gov

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