NCICT User Manual
The National Cancer Institute dosimetry system for Computed Tomography (NCICT) is a computer software application which can estimate the doses of radiation absorbed by organs and the effective dose for those having computed tomography (CT) scans. This program is built on an extensive compilation of organ dose conversion coefficients pre-calculated by Monte Carlo radiation transport simulations using multiple sets of computational human phantoms combined with a reference CT scanner. Organ dose calculation is conducted in four steps as described below: input patient characteristics, input scanner parameters, input scan coverage, and output of organ and effective doses. The Batch Calculation mode can automate dose measurements.
It is essential to input the details of a patient whose organ dose is sought. The size of the body is one of the essential factors affecting organ doses in CT scans. However, the information is not always available. Here, you can use age and corresponding body size as an alternative. You can select the patient’s age from five age groups: newborn, 1, 5, 10, 15 years old, and adult (assumed to be over 20 years). Once age is selected, the reference height and weight defined by the International Commission on Radiological Protection (ICRP) will be displayed (not editable). When you have patients with in-between ages not matching the ICRP age group, you may want to (1) interpolate organ doses calculated from younger and older ages (e.g., interpolate doses of 1-year and 5-year phantoms when you have 3-year-old patient), or (2) choose age group closest to your patient (e.g., select 5 years when your patient is 4-year).
Another scenario is when the height and weight of the patient are available. You can now ignore age but directly use height and weight for more accurate dose calculations. Please choose “Age Group” between “Pediatric” and “Adult” and then select gender. Within the age group, you can choose height and weight by referring to phantom maps, which will be displayed in a separate window when the button, “Show Phantom Height Weight Map”, is clicked. The height and weight distribution corresponds that of the body size-dependent phantom library.
You can select Fetus tab to calculate fetal organ doses or Mother tab to calculate the organ doses for pregnant women. Eight gestational ages are available for both fetus and pregnant women.
The next step is to input the technical parameters of your CT scanner. There can be two different scenarios. First, you may have CTDIvol available from your CT scanner, which is usually included in the dose (or protocol) page after the scan is completed. You will also need CTDI phantom type (16 cm head phantom or 32 cm body phantom) and tube potential (kVp) on which your CTDIvol is based. Please select the head or body filter, input CTDIvol, and then skip to the next step, “Scan range.” When a custom CTDIvol is entered, "Custom CTDIvol (mGy)" in blue color will be displayed.
When CTDIvol is not available, which is mostly the case in dose reconstruction for old CT scanners, CTDIvol needs to be reconstructed using available parameters. First, please select the manufacturer and model of the CT scanner in question from the dropdown menu. Next, please select the type of CTDI phantom between head and body. Then please input tube potential (kVp), current-time product (mAs), pitch, and total collimation (mm). Then NCICT will show normalized CTDIw (mGy/mAs) from a built-in nCTDIw library and CTDIvol will be derived using other parameters and displayed.
Tube current modulation strength can be selected among 0.0, 0.25, 0.5, 0.75, and 1.0, which will create a generic modulation curve based on a previously published algorithm. Please note that the algorithm is a generic model not specific to a certain scanner vendor or model. You can also define current limit (default is 600 mA) to limit the modulated mA. "Average CTDIvol (mGy)" (in blue color) will be automatically calculated by implementing slice-specific modulated CTDIvol.
Effective diameter (cm) will be displayed at the bottom with the two dose descriptors, Dose-Length-Product (DLP) and Size Specific Dose Estimates (SSDE).
Scan coverage (start and end location) need to be defined on the phantom selected. You have three options. First, the red box drawn on the phantom's frontal and rear views can be dragged using a cursor to adjust scan locations. The Second option is to directly enter scan locations in the two boxes at the bottom: scan start and scan end. The values represent the distance from the top of the phantom (e.g., 10 cm of scan start means scan starts at 10 cm from the top of the head). Once the values are entered, the location of the red box is automatically adjusted. The last option is selecting a protocol from “Predefined protocol” menu, which is based on the protocol used in the National Institutes of Health Clinical Center. There are seven scan protocols: head, neck, chest, abdomen, pelvis, abdomen-pelvis (AP), and chest-abdomen-pelvis (CAP). Once the protocol is selected, the red box on the phantom is automatically adjusted. The scan coverage will be automatically adjusted based on the anatomical landmarks when the phantom selection is changed.
Once all steps mentioned above are completed, organ absorbed doses (mGy) and effective dose (mSv) are displayed in the table on the right. The resulting doses are automatically copied to Clipboard so they can be pasted to other documents such as Microsoft Word, Excel, and, etc.
The organ names can be copied from the table by selecting the column using a mouse. The table includes all organs for which tissue weighting factors from ICRP Publication 103 are defined. Depending on the phantom's gender, the organs of opposite gender are zero (e.g., dose to the prostate and testes will be zero for female phantoms). Active and shallow marrow (bone surface in the former ICRP definition) doses are calculated from fluence passing through the spongiosa region within the skeleton combined with dose response function derived from Monte Carlo simulation of detailed spongiosa structure models. It should be also noted that gender-specific organ doses need to be averaged across male and female phantoms to derive effective dose based on the ICRP Publication 103 definition. The effective dose calculated for a male or female patient here is a gender-specific quantity that may be used for comparison of doses by protocol, hospital, scanner, and etc.
When dose to a large number of patients is of interest, you can use Batch Calculation feature. You can list patient- and scanner-related parameters into a csv-formatted file following the header in the first row. The NCICT folder contains an example batch file, ncict_batch_input.csv, as follows.
| Patient ID | Scan Start | Scan End | Phantom Group | Height | Weight | kVp | TCM strength | CTDI phantom | Average CTDIvol |
|---|---|---|---|---|---|---|---|---|---|
| 1 | 1 | 14 | 1 | 85 | 10 | 80 | 0 | 1 | 12 |
| 2 | 1 | 14 | 1 | 85 | 10 | 100 | 0.25 | 1 | 12 |
| 3 | 23 | 39 | 2 | 115 | 15 | 80 | 0 | 1 | 10 |
| 4 | 23 | 39 | 2 | 115 | 15 | 100 | 0.25 | 1 | 12 |
| 5 | 43 | 81 | 3 | 150 | 40 | 100 | 0 | 1 | 20 |
- Patient ID: numerical ID number for patients
- Scan Start: the distance (cm) of scan start from the top of the phantom's head
- Scan End: the distance (cm) of scan end from the top of the phantom's head
- Phantom Group: 1-pediatric female,2-pediatric male,3-adult female,4-adult male,5-fetus,6-pregnant woman
- Height: height of the patient in cm
- Weight: weight of the patient in cm
- kVp: tube potential
- TCM strength: number ranging from 0 (no TCM) to 1 (100% TCM)
- CTDI phantom: 1-16 cm CTDI phantom, 2-32 cm CTDI phantom
- CTDIvol: volumetric CTDIw
By clicking "Read Batch Input" under "Batch Run" menu, NCICT will import the input file and export the output organ doses. Batch Calculation works when you know your own CTDIvol.
- TCM adjustment for adult head and pediatric patients
- Monte Carlo errors next to the organ dose list
- Lymph node dose
- 20221214 Official release version 3.0.20221123
- 20221123
- NCICT2.0 published: Lee et al. “CT organ dose calculator size adaptive for pediatric and adult patients,” BPEX 8:065020 (2022)
- 20211123
- Error fixed when a blank line remained in the batch file which is sometimes caused by editing csv file in Excel
- 20211120
- Tube current profile per image slice is displayed on the left of the phantom picture.
- “Average CTDIvol” is displayed when TCM strength is greater than zero.
- “Custom CTDIvol” is displayed when CTDIvol is entered by users..
- Several bugs related to TCM in the batch module were fixed.
- 20211027
- Height and weight made uneditable when body size-dependent phantoms selected. The body size is only adjustable using the up and down arrows.
- Input for pregnant women (phantom group 5) and fetal (phantom group 6) phantoms can be used in batch input
- Menus for User Manual and User Forum added under “Help” menu
- 20211021
- mA will be calculated from custom CTDIvol values and TCM can be applied to mA
- 20210915
- Bug stopping the program when the batch input file is not available fixed
- mA and rotation time separated from mAs to properly adjust mA in the TCM mode
- mA limit added to limit too high mA for obese patients under TCM mode
- TCM mode disabled when a custom CTDIvol entered
- 20210520
- NCICT automatically selects a phantom best matching the height and weight of a patient in the batch mode
- 20210513 Official release version 3.0.20210513
- A batch function added (see the template input file: ncict_batch_input.csv)
- Tube current modulation added based on generic modulation profiles
- 20210307
- Effective diameter for pregnant women phantoms added
- 20200312 Official release version 3.0.20200312
- Speed up the scan range dragging on Windows version
- 20191205
- Mother’s dose added, NCICT 3.0.20191205
- Presented at RSNA 2019
- 20190301
- Eight pregnant phantoms with fetus added. Fetal organ dose made available.
- NCICT3.0 Build 20190301 launched
- 20181118 Official release version 2.0.20181118
- 98 more adult phantoms were added to the dose library, completing all 351 phantoms
- NCICTX presented at AAPM 2018, NCICTX renamed to NCICT 2.0.20181118
- 20160401
- 72 adult phantoms + 181 pediatric phantoms, NCICTX 20160401
- NCICTX presented at AAPM 2016
- 20151201
- NCICT1.0 published in Journal of Radiological Protection: Lee et al. JRP 2015
- NCICT1.0 presented at RSNA 2015
- 20141201 Official release version 1.0.20141201
- ICRP pediatric and adult phantoms replaced NCI phantoms: NCICT 1.0.20141201
- 20120418
- MATLAB version translated into Visual Basic 6.0 version of NCICT 1.0.20120418
- Batch routine implemented to automate multiple calculations
- Public beta testing started with a non-official data agreement form
- 20110517
- NCI phantom- and MATLAB-based NCICT 1.0.20110517