Saturday, 18 July 2015
28 September 2020
Interview with Dr. David Ackland and Dr. Farzad Keynejad:

“Mobile dual-plane fluoroscopy”

2012 April 22

Reflection of my mind

Have you ever thought about getting X-ray while running? You should have seen people who must be stationary while being X-rayed. However, researchers at the University of Melbourne have developed a novel device that can visualize the bones inside your body while moving. The main difference between this new device with similar fluoroscopy system is in its ability to follow the subject. Mobil dual-plane fluoroscopy lets the subject move freely so that the X-Ray system would follow a human joint to capture data from inside the body.

Mobile dual-plane fluoroscopy:

So far there are similar dual-plane fluoroscopy systems in the world that are fixed while the subject moves on a treadmill. The results may be different from walking or running in a normal situation that is called overground motion.

Why would researchers and clinicians like to know accurate movements of bones and internal structure of human bodies? Of course, they do this because motion analysis leads to skin motion artefact which means using markers on anatomical points is not an accurate method to find internal organs positions. Also, the main reason is to help understand and possibly prevent severe musculoskeletal diseases such as osteoarthritis (OA). When a young athlete faces a knee ligament injury, there seems to be a strong correlation between unstable knee and long term joint diseases. If researchers and clinicians could quantify very little abnormal movements caused by the injury, they probably could help patients to walk or run properly through more advanced and reliable trainings or aiding devices.

I have talked to two researchers who have been involved in this giant project that could potentially revolutionize the way scientist look at some devastating diseases such as OA and musculoskeletal disorders.

Dr. David Ackland who has recently become a faculty member in a reputable University of Melbourne and

Dr. Farzad Keynejad who has graduated from the University of Melbourne and now is a System Engineer of well-known international company called ANCA Motion

Although these researchers’ PhD project were in different areas of research, due to their experiences they worked in this project when they finished their PhD as postdoc and fellow researchers at the University of Melbourne.

·        What is Mobile dual fluoroscopy?

David: This is a device that utilizes X- ray fluoroscopy signal to visualize objects. It is similar to static ones when you get at a doctor. This one has been modified to benefit from high speed cameras. Two images from cameras attached to fluoroscopy system would enable us to create 3 dimensional model of the preferred joint. The new system follows a marker to move fluoroscopy system close to the human join while he/she is free to move.

·        What were the difficulties you face when you started designing the gantry?

Farzad: we started this project in 2009 as a LIEF grant under the supervision of Prof. Marcus Pandy. To give you an example you can think of tennis players and the type of cameras that are used nowadays so that you can see very slow motion of their soft tissue. This gantry is using the same concept whereas the cameras and X-ray devices are between 30 to 50Kg compared to very lighter cameras being used in sporting events. If you add other component needed to be carried, you will end up having about 250Kg weight. To move such a load accurately is a critical task. There are several studies with one or two fluoroscopy devices however they have used stationary devices. The main reason we used mobile one is to achieve high accuracy of bones positions during movements. In this new design, less field of view can be observed. Pose estimation can be an exhausting task using just one image, but we have solved that by having two images. Pose estimation is a prediction of relative position of bones with respect to each other during movement.

David: Single x ray can have accuracy of order of millimetre but in one plane while this new system provides accuracy of 0.2 mm for a reconstructed image. Also there is a limitation as to increase the number of X-ray and cameras because of harmful effects of such exposure to human.

Left: Dr. Farzad Keynejad / Right: Dr. David Ackland

·        In terms of design and application what are the novelties of this device?

Farzad: It is similar to any CNC machine, but for medical purposes. In fact the masses (250Kg with 5g speed where g=9.81m/s2) that we can carry as well as the rigidity of structure during motion capture pushes the limits of technology to the edges.

David: What can we do with this system is its novelty. More accurate data can be collected from joints. Then based on this new data, patient-specific mathematical models can be developed. These models could help predict joint forces, moments and muscle forces during different physical activities. Then the effects of implants on the joint motions can be analysed more accurately. People after ligament injury may lead to joint OA while observing and analysing their abnormal joint motion could help prevent these diseases.

·   Do you think such a system can be used widely for instance in a sporting event?

David: It seems that it is a research tool for the time being. With the aid of this device we could answer many clinical questions. I don’t think we could have a commercial one in the near future.

·       What would you add to it now if you wanted to redesign it?

Farzad: Not much because it has not been used in clinical experiments yet to see what needs to be changed. More experiments are required to be conducted in order to better understand the possible modifications to the device.

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