Using CTPClient

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CTPClient is a program for de-identifying medical images and transmitting them to a central site in a clinical trial. This article describes the user interface of CTPClient. It is intended for staff at clinical trial image acquisition sites who are responsible for selecting studies and sending them to the principal investigator.

1 Starting CTPClient

CTPClient is designed to be run in two ways. It can be installed on any computer, and run like any locally installed program. Alternatively, it can be placed on the web server of a CTP site and started by entering a URL into a web browser. In this article, the latter method will be described.

When CTPClient is started through a web browser, the clinical trial administrator will provide the image acquisition site a special URL. Since the URL is fairly long to enter, it is best to enter it once and save it as a bookmark or favorite.

Entering the URL causes the browser to download the program and verify the security certificate. Because the RSNA distributes the program with a self-signed certificate, all browsers display a dialog warning the user:

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To proceed, check the box and click Run. This will cause the browser to start the program. At that point, CTPClient will display its main window.

2 The CTP Main Window

CTPClient provides two ways to select patient studies for processing and transmission. It can allow the user to browse for images stored on the local computer. It can also receive images from a DICOM source like a workstation or a PACS. In this article, the latter method will be described.

When CTPClient starts, it displays its main window. Next to the main window is a frame describing how to select and transmit images. The instructions depend on how the program is configured to receive images. When the program is configured to obtain images from DICOM sources, the main window and the instructions frame look like this:

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In the picture above, note the footer bar. It is updated as the program runs to indicate the current status. If the instructions frame is closed or hidden, clicking on the Instructions button displays it again.

At this point, you must go to the PACS or workstation and send the images.

3 Selecting a Study for Processing

At any point, the Open DICOM Storage button can be clicked to display the list of images that have been received. The list contains the real patient names and IDs to make it easy to select the study for processing. (The processing replaces the patient identifiers with trial identifiers.) The images are grouped by patient, and within patient, by study. Within a study, the images are listed in order by series, acquisition, and image number:

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When the Open DICOM Storage button is clicked, the first study is selected automatically. To select a different study for processing, check the box for the study next to the patient's name. The boxes for studies act like radio buttons, so only one study can be selected at a time. This is necessary to allow for the entry of the subject ID before processing begins. Within a study, it is possible to de-select individual images, but this is not normally necessary.

When the study has been selected, click the Start button.

4 Entering the Subject ID

As part of the de-identification process, CTPClient must replace many identifiers in the images. Most of the replacement rules are defined in the configuration of the program, but it is necessary to obtain the Subject ID from the user. When the Start button is clicked, CTPClient displays a small dialog allowing the user to enter it.

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After entering the subject ID, click the OK button on the dialog.

5 Processing and Transmitting the Study

After the OK button on the dialog is clicked, CTPClient de-identifies and transmits the images. As each image is completed, a result is displayed at the end of the lines identifying the transmitted file.

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When CTPClient successfully completes the transmission of a file, it deletes the file from its internal DICOM Storage directory. After the transmission completes, clicking the Open DICOM Storage button again shows the remaining studies and images. If any of the images failed to transmit, they will still be shown in the window.

(Note: When CTPClient is used to process and transmit files from other directories, it does not delete the files.)

6 Stopping CTPClient

When finished with CTPClient, it can be left running, or it can be stopped by clicking the close box in the upper right corner of its window. When closing, if CTPClient has transmitted any images during the session, it displays a dialog allowing the user to save a file containing the original patient IDs and corresponding subject IDs. This file (in CSV format) can be opened by most spreadsheet programs.

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When saving the patient entries in a file that already exists, CTPClient appends the entries to the existing file data, allowing the file to accumulate all the patient IDs and subject IDs for studies transmitted over multiple sessions.

It is important to note that the file contains protected health information, so access to the file should be controlled. If you do not want the file, click Cancel instead of OK, and CTPClient will not write it.

If any errors occurred while CTPClient was running, it offers to save its internal log when it shuts down. This log should be passed to the trial administrator, who will send it to the program author.