DICOM Configuration Parameters

What it Means for Radiologic Technologists and PACS Administrators

To the rad techs out there.  Do you want to learn more about DICOM?  Specifically the DICOM configuration parameters of the modalities you use?  To the prospective PACS administrators.  Where would you get started on configuring some of these modalities?

DICOM configuration parameters can be confusing for the uninitiated. And as different modalities have unique user interfaces, it is important to understand the shared fundamental concepts.  For example, a CT modality from Philips may have a different looking user interface than a GE modality.  However, the core configurations are the same.  Understanding the core concepts will allow you to properly configure these parameters.

So, what are DICOM configuration parameters? In short, they are the settings that dictate how your modality communicates with other devices such as a PACS. Each setting is responsible for a different aspect of the communication process.  We will review DICOM operations and services in a separate module.

In this module, we will review DICOM configuration parameters for the end-users such as rad techs.  But also dive into more detail for the prospective PACS administrators out there.  To get more detailed information, subscribe to our free PACS training course.  More of these topics will be published over time.

What Are DICOM Configuration Parameters, and Why Are They Important?

DICOM Configuration Parameters are settings that need to be configured correctly for DICOM devices to communicate with each other. Because DICOM-based devices must adhere to the DICOM standard, they all follow the same set of rules which allow interoperability with other DICOM devices.  The standard determines the inputs and constraints of what values can be entered to configure the device.

If these configuration parameters are not set up correctly, images may not be transferred properly or at all between devices. This can cause major problems for radiologic technologists who rely on DICOM images to do their job. PACS administrators especially need to be knowledgeable of these parameters to configure and maintain the PACS properly.

Common Terms Explained: AET, Static IP, Port, SCP/SCU

There are three mandatory parameters required to establish a DICOM connection between two devices.  AET, IP and Port.  Within a communication between the two devices, one is the SCU while the other is the SCP.  Let’s quickly review these terms.

AET (Application Entity Title):

The AET is a unique identifier for a DICOM device. This is important because it allows other devices to find and connect to the device.  The standard requires a 16 character limitation to the name.  The AET is also case sensitive.  

IP (Internet Protocol) Address:

This is a unique identifier for a device that is connected to the network.. Every DICOM device needs its own IP address for it to be properly identified by other devices.

Static IP vs Dynamic IP.
One of the most important DICOM configuration parameters is the IP address. This parameter defines a device’s location on the internet or local network. Read more about networks here.  There are two types: static and dynamic. A static IP is an IP address that does not change. This is important because if the IP address of a DICOM device changes, other devices will not be able to find it. 

A dynamic IP, on the contrary, is an IP address that can change at any time. This can be problematic because if the IP address changes, other DICOM devices will not be able to find the device.

Port:

The port is a communication endpoint that software applications use to send or receive data. This virtual pathway allows data to travel between two devices. DICOM images are transferred using a specific port called the DICOM port. This port is important because it allows other devices to find and connect to the device.  A common port for DICOM is 104, though a variety of other ports can be used.

SCP/SCU:

Service Class Provider (SCP) and Service Class User (SCU) are roles that define which PACS component initiates a DICOM communication session.  Storage Class User (SCU) is the user of the service.  Storage Class Provider (SCP) is the provider of the service.

For example, storing magnetic resonance images from the MRI modality to PACS.  In the storage service the MR modality is the SCU trying to store images to the PACS.  PACS is the SCP, allowing the images to be stored.

How To Configure Your Modalities And PACS Correctly Using These Parameters

As a radiologic technologist, it is important to understand the basic concepts of DICOM to work effectively with PACS. This includes understanding DICOM configuration parameters. A PACS administrator should proficiently know how to configure these parameters accordingly.

Configuring your Modalities and PACS correctly

It is important to configure your modalities and PACS correctly to avoid image transfer problems. This includes setting the correct IP address, port, and AET.

As stated in the definitions above, each device must have their own AET, IP and port.  Each DICOM device must also know the AET, IP and port of any other device it communicates with.  

In this case, the modality must have its own AET, IP, Port.  As an example, let’s imagine we have a CT modality that we must configure to a PACS.  We have already assigned a name, IP and port to the two devices.  Here is what we will begin with.  We will first configure the following into each device.

What we will configure the modality as:
AET:  CT01
IP:  192.168.1.1
Port:  104

What we will configure the PACS as:
AET:  PACSPROD
IP: 192.158.1.38
Port: 12000

Now that we’ve configured names/AET of our devices, let’s connect them to each other.

Instructions for configuring your modalities and PACS:

1. Open the DICOM configuration utility on your modality.

2. Enter the IP address, port, and AET information into the DICOM configuration utility.

Following our example above, you would enter the following PACS destination into the CT modality:
AET:  PACSPROD
IP: 192.158.1.38
Port: 12000

3. Save the changes and exit the utility.

4. Repeat these steps for all of your modalities.

5 Open the DICOM configuration utility on your PACS.

6. Enter the IP address, port and AET information of the modality into the utility. 

Following our example above, you would enter the following CT modality into the PACS:
AET:  CT01
IP:  192.168.1.1
Port:  104

7. Connect to your PACS by performing a network ping to confirm there is a basic network connection.  Not all modalities have this option available.

8. Establish a DICOM connection to your PACS by performing a DICOM C-ECHO.  This confirms there is a valid DICOM connection.

9. Verify that images are transferring correctly by sending Test images.  Ensure you are getting a successful send notification from the device.

10. Verify that all images have arrived in the PACS by viewing the images in the PACS viewer.

Calling AET vs Called AET

It is important to understand these terms as they may need to be defined during configuration. As we know now…  In a DICOM communication, between two devices, each device has an AET.  During a communication session, one can serve as the Calling, while the other as the Called.  The Calling AET is the name of the initial DICOM device reaching out to communicate with the other.  The device on the receiving end is the Called AET.

For instance, based on our example from above… If the CT reaches out to the PACS to establish a DICOM C-ECHO to verify connectivity then;   The Calling AET is CT01.  The Called AET is PACSPROD.

Calling AET:  Think of it as being the person who calls other people on the network.  The calling AET is the name of the person making these calls out.
Called AET:  Think of it as the name of the person being called.  In this case it is the name of the PACS.

Tips for radiologic technologists and PACS administrators to remember when setting up DICOM devices

• Verify each device has its own unique IP address.
• Some wireless modalities are set to DHCP (an IP that changes each time it connects to the network).  You can either work with the modality vendor to set this to a preferred static IP or have your organization’s networking team create an IP address reservation. So the same IP can be assigned each time the modality attempts to connect to the network.    
• If a modality’s static IP address needs to be changed for any reason, make sure to update the IP in PACS accordingly.  Also within any other DICOM devices that have this modality configured.
• The DICOM port must be open on both the sending and receiving devices for images to be transferred properly.  Ensure there is no firewall blocking this port.
• Make sure the AETs of all devices are properly entered into the PACS system.  Be careful of case sensitivity.  

FAQs About DICOM Configuration Parameters

What is the difference between DICOM and PACS?

DICOM and PACS are two acronyms that are often used interchangeably, but they actually refer to two different things. DICOM – which stands for Digital Imaging and Communications in Medicine, is a standard used for storing and transmitting medical images.

PACS, on the other hand, stands for Picture Archiving and Communication System. PACS is the system used to store, manage, and distribute medical images. While DICOM is the standard for image format, PACS is the system that actually stores and transmits the images. DICOM and PACS are required to store and transmit medical images properly.

Q: Do I need to understand all of these parameters to use DICOM devices?

A: No, not as the end user of these products.  You don’t need to understand all of the parameters to use DICOM devices. However, it is always helpful to have a basic understanding of how they work in order to troubleshoot any problems that may arise.  PACS administrators on the other hand have to be very familiar in order to resolve any problems that are escalated to them.

Q: I’m having trouble transferring images from the modality to PACS. What should I do?

A: First, check that the IP addresses, ports, and AETs are all configured correctly. Find out if the vendor made any recent changes or upgrades to the modality.  If nothing has changed and you’re still having trouble, consult your PACS administrator or IT department for help.  

Final Words: Check Out Our Training Courses For More Information

Understanding these parameters is essential for anyone working with PACS or DICOM modalities. Incorrect settings can result in lost images, delayed diagnoses, and a host of other problems.

If you’re a technologist and your institution works with PACS or modalities, be sure to brush up on your knowledge of DICOM configuration parameters.

Looking for more PACS training? Subscribe to us for more PACS Administrator Training modules and visit our Youtube page for a DICOM for dummies type of explanation.  For a condensed summarized version, check out our Premium Study Guide.  Rad techs and Informatics professionals can earn 3.5 Category A CEs upon successful completion of the course. Link below.

PACS Boot Camp is for anyone who wants to learn more about configuring and managing a PACS. And as always, feel free to contact us with any questions. We’re here to help!

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