When purchasing a refurbished CT simulator like the GE Discovery 590 RT, one key feature to consider is its 4D respiratory gating capability. This technology helps manage tumor motion caused by a patient’s breathing. GE offers two common options for 4D imaging: Advantage 4D and Deviceless 4D.

What is the difference between these two solutions, and which is right for your clinic? In this article, we’ll take a closer look at both options to help you decide which is the better fit for your clinic.

What Is 4D CT?

4D CT imaging creates a series of images that show how a patient’s organs and tumors move during the breathing cycle. This is especially useful for lung and upper abdominal cancers, where tumors can shift quite a bit between inhaling and exhaling.

4D imaging helps doctors better see and outline tumors, plan treatments that account for motion while minimizing exposure to surrounding healthy tissues.

Studies show that 4D CT can track tumor movement very accurately, even when breathing is irregular. For example, a study by Baley et al. (2021) found that 4D CT and 4D cone-beam CT matched tumor motion within 1 to 2 millimeters. This means 4D CT is reliable for planning radiation treatments.

To learn more about how respiratory gating improves accuracy in radiation therapy, check out our recent blog on the clinical benefits of gating techniques.

Option 1) Advantage 4D: Device-Based Gating

Advantage 4D uses an external device, like the Varian’s RPM (Real-Time Position Management), VisionRT, or C-Rad camera systems to track how the patient’s chest or belly moves while breathing.

External Gating Cameras Integrated with Advantage 4D

Advantage 4D’s device-based gating depends on specialized external respiratory gating hardware to capture the patient’s breathing motion accurately during CT scans. While Advantage 4D is GE’s 4D CT image reconstruction software, it works in combination with third-party camera systems that provide the real-time respiratory signals needed for gating.

Commonly integrated gating camera systems include:

These external gating systems complement Advantage 4D by delivering robust respiratory signals, ensuring accurate tumor motion tracking and consistent image quality. The choice of gating camera often depends on your clinic’s existing equipment and workflow preferences.

Option 2) Deviceless 4D: Internal Motion Tracking

Deviceless 4D, as the name suggests, eliminates the need for external hardware. Instead, it analyzes the CT images themselves to track breathing—looking at changes in the lungs or diaphragm to figure out motion.

A recent 2024 study comparing RPM-based gating and Smart Deviceless 4D showed no significant difference in motion detection accuracy for para-aortic nodal irradiation, suggesting that Deviceless 4D can perform just as well for treatment planning in many clinical scenarios.

Which Option Is Right for You?

Both systems are effective. The best choice depends on your clinical workflow, equipment setup, staff experience, and patient population.

Feature	Advantage 4D (Device-Based)	Deviceless 4D
External equipment required	Yes (e.g., RPM system, VisonRT, or C-Rad systems)	No
Setup time	Longer	Faster
Patient comfort	Moderate	More comfortable
Motion tracking method	External surrogate	Internal anatomy (diaphragm, lungs)
Verification trace	Yes	No

 

If your clinic already uses external gating for treatment (like RPM with Varian), Advantage 4D may fit better into your workflow. For clinics seeking a simpler setup with fewer devices and faster scans, Deviceless 4D may be the better fit.

Final Thoughts

As more refurbished GE Discovery 590 RT units enter the secondary market, understanding the capabilities of their 4D options is critical for clinical decision-making. At Radiology Oncology Systems, we not only help clinics evaluate equipment by price and availability, we also consider how each system fits into your treatment planning goals. If you’re considering a refurbished CT simulator and would like guidance comparing configurations, our team is happy to help.

FAQs: 4D CT Imaging on GE Discovery 590 RT CT Scanner

What is 4D CT and why is it used in radiation therapy?

4D CT creates a sequence of images that show how a tumor moves as a patient breathes. This helps radiation oncologists plan treatments that are more precise, especially for cancers in the lungs and upper abdomen where tumor motion can vary significantly during the breathing cycle.

How does Advantage 4D work on the GE Discovery 590 RT?

Advantage 4D uses external respiratory gating hardware such as Varian’s RPM (Real-Time Position Management), VisionRT, or C-Rad systems. A camera tracks breathing motion in real time, which is then used to sort and reconstruct the CT images according to different phases of the breathing cycle.

What is Deviceless 4D and how does it compare to Advantage 4D?

Deviceless 4D does not use any external hardware. Instead, it analyzes internal anatomy—such as the diaphragm’s movement—directly from the CT images to track respiratory motion. It simplifies the setup and improves patient comfort, while still offering clinically useful motion data.

Is Deviceless 4D accurate enough for clinical use?

Yes. A 2024 study comparing RPM-based gating (Advantage 4D) and Smart Deviceless 4D showed no significant difference in motion detection accuracy for para-aortic nodal irradiation. This suggests that Deviceless 4D can be a reliable option for many treatment planning scenarios.

How do I choose between Advantage 4D and Deviceless 4D for my clinic?

If your clinic already uses external gating systems like RPM, VisionRT, or C-Rad for treatment, Advantage 4D may better align with your workflow. If you want faster setup times and improved patient comfort, Deviceless 4D offers a streamlined solution without compromising motion tracking performance.