Microwave system design for bone fracture imaging and recovery monitoring

Project Title

Microwave system design for bone fracture imaging and recovery monitoring

Project Area of Specialization Biomedical EngineeringProject Summary

Fractures in the tibia are the most common long bone fractures ranging from minute stress  fractures to tibial diaphysis in adults and toddlers. C. M. Court-Brown at royal infirmary of Edinburgh reported the annual incidence of open fractures of long bones is estimated around 12  per 100,000 persons with 40% occurring in the lower limb in his research. According to physicians, stress fractures are frequently encountered injuries, especially in the discipline of sports medicine, they are disabling and their recurrence rate is 60%. The common methods involved in the detection of fractures are X-ray radiography, CT scan, MRI and nuclear medicine bone scanning.  

X-ray radiographs are considered the most affordable and common method for fracture detection but they are often not positive for stress fractures until approximately after 2 to 4 weeks a new bone formation becomes visible in radiography. The rest of the detection methods are quite costly and aren’t affordable for majority of the Pakistani population comprising of the people in the rural and urban areas. Research has also shown that x-rays have ionizing effects and are identified as carcinogen by the World Health Organization (WHO) and the USA. It is shown that 0.4 percent of cancers in the US are caused by CT scans which computes its image from many x-ray measurements from different angles to produce a cross-sectional image of specific areas of a scanned object.

MWI systems are a revolutionary step towards non-invasive, radiation-free and affordable biomedical imaging techniques. Our project is generated towards making a portable and easily manageable device for the early detection of stress fractures in patients using Microwave imaging techniques, which is not only extremely accurate and precise but also very cost-efficient and harmless. The first part of our project includes a ring resonator operating at a fixed MW frequency which detects any change in the dielectric of the human tissue caused due to a fracture and its respective parameters can be processed to obtain an image. For the second part, we are using Vivaldi antennas operating at a MW band to scan the affected area and its measurement are recorded and refined using imaging algorithms to produce an image.

Project Objectives

The main objectives of our research project are:

1. To generate a portable, safe and efficient microwave imaging system as a diagnostic system for the detection of bone fractures.
2. To conduct trials on animal and human subjects for a detailed study and to use our observations and findings to further improve and refine our results.
3. To commercialize MWI systems on a large scale for clinics and hospitals.

Project Implementation Method

For the detection of fracture, our resonator will sense it by monitoring the dielectric constant of that bone and its surrounding tissue, a fractured bone, and its surrounding tissue will have deviated dielectric values causing a change in its resonant frequency i.e. dip of the S11-parameter. To achieve this purpose, a microstrip ring resonator is specifically designed and used to meet the primary aim of detection of fracture in the human tibia. The data is acquired from the ring resonator and is used to construct an image of the precise location of the fracture in tibia bone.

Figure 1: Concept model for Vivaldi Antennas

As a result, the system will be capable of performing the following tasks:

1. Hardware structure to stabilize the sensor and isolate it from environmental factors.
2. A sensor that can change its resonant frequency according to bone characteristics.
3. Processing of shifts in the resonator’s resonant frequency to construct the image.
4. Image processing to detect the fracture in the previously constructed image.

Another approach is by using an Antipodal Vivaldi Antenna that scans the bone and we will design a hardware setup that can rotate these two designed antennas around the phantom at opposite ends and use the data to construct an image. VNA (vector network analyzer) would be used for recording the data and a stepper motor is used with Arduino to rotate the structure as shown in the figure below.

Figure 2: Concept model for Ring Resonator

The data from the ring resonator and the Vivaldi Antenna are sent to MATLAB from VNA through Arduino and LabView. The further processing is done on MATLAB by using the Lanczos algorithm to construct the image from the data.

Benefits of the Project

It will be the first prototype of a complete MWI system for bone fracture detection and testing in Pakistan.

1. Microwaves are completely safe and have low energy i.e. it is 10E-9 times lesser than the energy of X-rays. Microwave imaging can replace radiography and reduce patient’s exposure to radiation to minimal.
2. Microwaves have been used in industries for a long time in non-invasive testing and defect detections in electronics. They are currently trending in the biomedical community for cancerous tumor detection.
3. Successful MWI systems will attract more investors for the advancements of biomedical technology.
4.  It will increase the biomedical diagnosis and also increase the proficiency of the medical community in MWI diagnosis.
5. It will help the doctor as well as the patient to mitigate the hustle of going on a specific floor for X-ray because of the embedded design of our solution.

Technical Details of Final Deliverable

1. A limb mimicking bone phantom to mimic human tissue’s dielectric properties.
2. Design of Antipodal Vivaldi antenna at 2-6 GHz and ring resonator at 2.45 GHz resonant frequency.

 

Figure 3: Antipodal Vivaldi Antenna 

                       Figure 4: Ring Resonator                 

1. Hardware setup using MATLAB and VNA to take different measurements of the phantom and record the data.
2. Efficient imaging algorithm for Microwave imaging by using Lanczos to construct the image of fracture within the tibia bone.

The Flowchart of Project implementation is as follow:

Final Deliverable of the Project HW/SW integrated systemCore Industry MedicalOther Industries Education , Health Core Technology Wearables and ImplantablesOther Technologies Clean TechSustainable Development Goals Good Health and Well-Being for People, Affordable and Clean EnergyRequired Resources

Item Name	Type	No. of Units	Per Unit Cost (in Rs)	Total (in Rs)
			Total in (Rs)	69000
Substrate Materials	Equipment	1	25000	25000
Prototype Development	Equipment	1	15000	15000
Phantom Development/ 3D printing	Equipment	1	15000	15000
Phantom Material Cost	Equipment	1	7000	7000
Misc.	Miscellaneous	1	7000	7000