cbct instructions

8/11/2019 CBCT Instructions

1/4

CBCT QA Analyzer

Version 0.95

Written in MATLAB 2012b by James Kerns ([email protected])

Purpose:To analyze cone beam CT (CBCT) images of the CatPhan phantom for the purposes of analysis

for routine quality assurance (QA). The program will automatically correct for small setup differences of

the phantom. There are manual tools as well if the automation fails. Results of the various modules can

be saved into a report with clear pass/fail results or into an Excel sheet for analysis outside the program,

although a lightweight database reviewer is included.


2/4

Instructions:For first-time use, the MATLAB Compiler Runtime (MCR) must be installed on the local

computer. This can be downloaded from themathworks website.Once the MCR is installed the program

can run like any other program via double-clicking. After a moment, the GUI will appear.

The steps to do the QA correspond to the numbered buttons at the top of the program. First,

enter your name and the name of the machine the images are from. Then, load ALL of the images of thedataset at once. The program will read in the images and then display what it thinks is the HU module.

The images can be viewed by clicking on the arrows or scrollbar immediately below the images or by

entering the desired slice number into the box to the right of the scrollbar.

The four small boxes to the right of the main image show what images the program will use to

calculate on.

When ready, click Process CBCT to do the analysis. The HU ROIs, spatial resolution lines, and

uniformity ROIs will show up on the slices they were calculated on in the main viewer. Numeric results

all show up in the Results panel on the right. The slice that each parameter was calculated on is shown

along with the units of the results. At the bottom is a PASS/FAIL result for the HU, Geometry, and

Uniformity sections. Low contrast is difficult to determine because for some CBCT modes no low

contrast bubbles can be seen. This section is left up to the physicist to determine what a passing result

is.
http://www.mathworks.com/products/compiler/mcr/index.htmlhttp://www.mathworks.com/products/compiler/mcr/index.htmlhttp://www.mathworks.com/products/compiler/mcr/index.htmlhttp://www.mathworks.com/products/compiler/mcr/index.html


3/4

If the results look weird or are out of tolerance it could be that the slices calculated on were not

perfectly situated. If this is the case then use the tools at the top right to adjust the ROIs into the correct

position. Note that the geometric calculation is unaffected.

Before saving the results dont forget to complete the low contrast section. This can be done by

clicking the Low Con. Preset button, which will adjust the window/level to an appropriate setting and

move the main image to the low contrast slice. Adjust the window/level for the best viewing of the

bubbles. Enter the number seen into the Bubbles Visible entry box.

Once everything is satisfactory the results can be printed to a PDF report, which will contain the

same information, by clicking the Save to PDF button at the top. A new figure will pop up along with a

save file dialog box. Save the file to PDF; the initial destination is the folder of the images.


4/4

If desired, the results can be saved into an Excel file to form a database. This is only for

redundancy and is not required. If saved into a database, the results of up to the previous four months

can be reviewed.

cbct instructions

Documents