Research Spotlights

By Georgia Barrington-Smith & Dr Rebecca Duncan

For decades, conventional X-rays have been invaluable in clinical settings, enabling doctors and radiographers to gain critical insights into patients’ health. While traditional X-rays are still widely used, they are limited in the depth of information they can provide. New, advanced multimodal techniques, like phase-shift and dark-field imaging, can offer more detailed images, revealing not only bones and metal implants but also microstructures and surrounding soft tissue.

Unlike conventional X-ray imaging, which focuses on the absorption of X-rays by the sample (attenuation), phase-shift imaging captures changes in the phase of X-rays as they pass through the sample. In addition, dark-field imaging highlights small structures such as tiny pores, cracks, or granular textures, providing detailed information beyond the spatial resolution of traditional X-rays.

Enhancing X-ray imaging efficiency with multimodal techniques

Research into multimodal techniques has introduced one promising method: Speckle-Based X-ray Imaging (SBXI). With a simple experimental setup and ability to produce high-quality images with minimal data, SBXI uses a spatially-varied medium (such as sandpaper or textured materials) placed between the X-ray source and detector. This creates speckles—tiny variations in the intensity of the X-rays as they pass through the sample. These speckles act as markers, helping to track the X-ray wavefronts. By analysing how the speckles change as they pass through the sample, additional structural information can be recovered.

Although SBXI shows great potential, there are significant challenges hindering its development, such as the longer time required to construct high-quality images. Therefore, fast, efficient computer-based algorithms are crucial not only for reducing computational time, but also for minimising the radiation exposure to the patient during image reconstruction.

Samantha’s steps towards speckle-based X-rays

Samantha Alloo, an AINSE PGRA scholar, and her collaborators at ANSTO and the University of Canterbury have developed a fast, computationally efficient algorithm capable of reconstructing multimodal signals in just a few seconds. This new algorithm, called Multimodal Intrinsic Speckle-Tracking (MIST), provides on-demand multimodal imaging with low radiation exposure to the patient, or other delicate samples.

MIST uses the principle of energy conservation at small scales to track speckles and generate detailed images in Speckle-Based X-ray Imaging. The dark-field images it produces are especially useful when combined with other traditional X-ray imaging methods, such as Small-Angle X-ray Scattering (SAXS), as they can reveal information about sample structures beyond the limits of the imaging system’s spatial resolution. This capability has already proven valuable in applications including clinical mammography, biosecurity, and engineering crack detection.

Future directions for Samantha’s algorithm

Samantha and her team aim to further develop MIST to create a user-friendly SBXI setup at the MicroCT beamline at ANSTO’s Australian Synchrotron. This setup is designed to retrieve high-quality data comparable to, or even surpassing, well-established imaging techniques. The goal is to make these algorithms computationally efficient and general enough to be applied in a wide range of real-time synchrotron and laboratory experiments.

Samantha hopes to extend the MIST algorithm to work with materials whose properties vary depending on the direction that X-rays travel through the material. This will allow the reconstructed dark-field signal to reveal information about the sample’s microstructure orientation, making MIST suitable for a broader range of samples. This expanded approach will contribute to the overall goal of creating a more robust and user-friendly technique for clinical applications.

Finally, while utilising the MIST algorithm to conduct SBXI experiments, Samantha also hopes to develop a dark-field tensor tomography protocol. This protocol promises to deliver more detailed information about a sample’s internal structure by using SBXI techniques to capture its orientation in three-dimensional space.

AINSE are proud to spotlight Samantha Alloo for her groundbreaking work!

To explore more incredible research by our AINSE scholars, visit ainse.edu.au/research-spotlight.

We’re hanging up our stethoscopes and turning our attention to Bushfire Awareness in April, where we’ll spotlight two AINSE scholars doing crucial research on Australia’s bushfires and explore how science is driving better outcomes for our community.

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By Georgia Barrington-Smith & Dr Rebecca Duncan

Medical radiation procedures, such as diagnostic imaging and radiation therapy, are critical in modern healthcare, providing life-saving detection and treatment tools for people suffering from diseases like cancer. Recent technological advancements have led to a new generation of radiotherapy treatments that promise to further enhance patient outcomes.

Developing radiotherapies

Unlike traditional radiation therapies that use large beams with broad target areas, microbeam radiation therapy (MRT) uses tiny, highly focused beams for more precise treatment. Unfortunately, traditional detection equipment cannot keep up with the steep dose changes and high intensities of MRT treatments; the small size and high intensity of the beams presents a considerable challenge in accurately measuring the amount of radiation being delivered to the patient. Therefore, there is a need to design a new generation of sensors with three key considerations:

1. Ultra-fine spatial resolution (down to the micron level),
2. The ability to mimic tissue behaviour in the human body to ensure accurate measurements across varying radiation energies, and
3. A high tolerance to radiation, ensuring the device remains functional even under the intense radiation levels associated with MRT.

Additionally, with real-time monitoring now mandatory in many countries to detect, evaluate, and correct radiation dose deviations during treatment, the sensors must be adaptable to the patient’s shape and provide immediate feedback.

Jessie helps develop highly specialised sensors

Consequently, Dr Jessie Posar, an AINSE ECRG recipient and 2022 AINSE Scholar Gold Medallist, along with her collaborators at ANSTO and the University of Wollongong, embarked on a research effort to develop wearable X-ray sensors that could monitor patients throughout their treatment to track radiation dosage.

The sensors were crafted from a carbon-based flexible material mounted on a specialised plastic film called Kapton, which was selected for its superior durability and flexibility compared to commercially-used polyethylene (PE). The sensor was designed with a very thin layer (260 nanometers thick, about 200 times thinner than a human hair) composed of two organic materials: P3HT (a polymer) and o-IDTBR (a special chemical compound). The sensor was connected to two types of metal contacts—Indium Tin Oxide (ITO) at the bottom and Aluminum at the top—to measure the X-ray signals.

To test the effectiveness of this new sensor, the team developed a custom-made system to read the sensor data in real time. The sensors’ response was then evaluated using the Imaging and Medical Beamline at ANSTO’s Australian Synchrotron, one of only two places in the world currently developing MRT technology.

Testing the feasibility of the X-ray sensor

Using multiple filters to adjust the energy of the X-ray beams to track the sensor’s responsiveness, the team discovered that when the sensor was mounted on Kapton film, it was sufficiently sensitive to accurately measure the required radiation doses with high spatial resolution. However, the team also detected that the Indium Tin Oxide layer was interacting with the incoming beam, which in turn negatively impacted the sensor’s performance.

Further testing revealed that using polyethylene instead of Kapton, caused the sensor to perform less efficiently because the current from the sensor flipped direction during testing, making it unreliable. They determined that the polyethylene caused a build-up of electrostatic charge at the interface between the polyethylene and the organic material, which interfered with the sensor’s performance. This problem was not present when Kapton film was used.

How robust is the sensor?

Next, the team tested how well the sensor could handle high levels of radiation. Overall, the sensor performed moderately well, showing a performance drop of approximately 35% when exposed to high doses. This is a significant improvement over previous radiation hardness studies on existing devices that showed performance decreases of 65%. This reinforced the new design as being more durable than pre-existing sensors.

Jessie’s research demonstrates the development of a new kind of sensor that could help make radiation treatments even more precise and safe. These sensors could improve future treatments for diseases like cancer by providing a means of monitoring the doses associated with new precise, high intensity therapies such as MRT, making the procedures safer and more effective.

AINSE are proud to spotlight Jessie Posar for her outstanding work!

To explore more incredible research by our AINSE scholars, visit ainse.edu.au/research-spotlight.

Don’t take your finger off the pulse as we bring you our next article in Medical March, showcasing the wonderful work of Samantha Alloo, who investigates the use of multi­­­modal signals to uncover high-resolution details in clinical X-ray scans.

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