MRI-CT Compatible Dynamic Motion Phantom

Tech ID: yue000920



While 4-dimensional (4D) computed tomography (CT) has been the primary method for radiotherapy planning, the use of 4D magnetic resonance imaging (MRI) is becoming increasingly important since it provides greater soft-tissue contrast and allows for diagnosis, treatment planning, patient monitoring, and response evaluation without subjecting the patient to radiation. Further, the recent development of MRI-LINAC systems heightens the need for MRI-based methods for in-treatment room monitoring. However, the use of 4D MRI for radiotherapy planning requires equipment, such as a dynamic phantom, that can provide measures of quality assurance. Most commercially available dynamic phantoms are designed for CT and/or X-ray guided radiotherapy and use electromagnetic motors to move the phantom. These phantoms are typically not MRI compatible, and may potentially be MRI-safety hazards. Of the available MRI-compatible phantoms, image quality suffers due to the use of a motor. Thus, there is a need for improved MRI-compatible dynamic phantoms. In addition, it would be valuable to provide quality checks across both CT and MRI with the same phantom, yet no commercially available phantom can be used with both imaging modalities.



Dr. Yong Yue from the Department of Radiation Oncology at the Cedars-Sinai Medical Center has developed a motion phantom that can validate both MRI and CT imaging sequences for quality assurance of MRI- or CT-guided radiotherapy. The phantom consists of a gadolinium gel suspended in a low-concentration gadolinium fluid and has no metal components. It can produce dynamic motion through the use of an air pump placed outside of the imaging room. The device simulates human respiratory rates (2-20 s/cycle) and breathing depths (3-30mm). The design of the phantom successfully provides high image contrast and minimizes the image quality differences between MRI and CT.


Stage of Development

Prototype available and tested



•       By distancing the pump from the imaging phantom, image artifacts and safety hazards caused by electromagnetic motor are eliminated

•       Compatible with multiple imaging modalities (4D MRI, 4D CT)



•       Validate accuracy and performance of clinical procedures in both 4D MRI and 4D CT


Intellectual Property

• PCT application filed - PCT/US2016/044338

o Nationalized in China, Europe, Japan and the U.S.



Yue et al. Geometric validation of self-gating k-space-sorted 4D-MRI vs 4D-CT using a respiratory motion phantom. Med Phys. 2015 Oct;42(10):5787. Link

Patent Information:
For Information, Contact:
Julien Brohan
Yong Yue