Radiotherapy is one of the most widely used forms of cancer treatment in the world. As such, it is essential that we must be able to target the cancer cells reliably and accurately whilst also sparing the normal tissue surrounding them. As such, a method to detect treatment errors during radiotherapy must be developed. The LUSY system dosimeter is a device that can detect X-ray doses in real-time, thereby providing medical personnel an accurate means of measuring the dosage and adjust it accordingly.
Photo by National Cancer Institute on Unsplash
In 2020, more than 19 million cancer cases were diagnosed globally with around 10 million such cases resulting in the death of the patients. Malaysia alone reported more than 48000 new cancer cases. Many types of treatment are used to combat this threat, with radiotherapy being one of the most widely used. Radiotherapy works by exposing the tumour to high doses of X-ray radiation, killing cells in the process. This dose is more than a thousand times higher than the typically X-ray doses used during anatomical imaging. Because of the inherent danger, it is crucial that the tumour is targeted accurately so as to avoid damaging the normal tissues surrounding it. As such, radiotherapy often requires rigorous quality assurance (QA) to ensure correct treatment delivery. But despite this, treatment error can still occur without a proper mechanism or technique to capture the error during treatment delivery.
“What if we can make this safer for patients? What if we can detect treatment errors during radiotherapy and intervene immediately?” asks A/P Dr. Jeannie Wong.
One method of QA that is routinely used in radiotherapy procedures is the application of a dosimeter. This is a device that can measure radiation and thus ensure accurate and safe delivery of radiotherapy to patients. There are different types of dosimeters available, each with its own advantages and limitations. Combining different dosimeters will allow the medical physicist and personnel in-charge of QA to measure the radiation in various clinical setups but doing so is often labour-intensive and does not allow for real-time detection and validation.
In light of this issue, Dr. Wong and her team have developed the LUSY (acronym for radioLUminescent dosimetry SYstem), a novel radiation detector that can be placed on the patient’s body to measure radiation doses in real-time.
The LUSY system dosimeter works via the radioluminescent principle, a phenomenon where a material produces light upon being bombarded with radiation. First, a plastic sensor is placed on the patient's skin at the treatment area during the procedure. As the X-ray is delivered into the patient’s body, the sensor will emit light upon interacting with the radiation, transmitting this light along an optical fibre cable to a photodetector. This photodetector will then capture the emitted light and convert it into an electrical current which represents the X-ray dosage. The system will continue to measure the X-ray dosage until the treatment is complete, and the plastic sensor is removed.
The LUSY dosimeter is safe for the patient and personnel because it does not involve direct high voltage. The plastic sensor itself is small and harmless, being a 1 mm wide rod with a length of 3 mm. As the X-ray dose is measured during treatment delivery, the dosage can be adjusted or validated in real-time thereby reducing the treatment error. LUSY can be connected to a specialised photodetector in order to increase its sensitivity and thus measure very low X-ray doses. Finally, LUSY has shown potential in other areas involving X-rays, such as medical imaging where it can be used for X-ray dose measurement with a patient or routine quality assurance of the X-ray machine.
LUSY will help revolutionise the cancer care by providing medical professionals with a means of measuring X-ray dosage in real-time, thus allowing them to make proper adjustments to ensure a safer dosage for the patients.
Figure 1 showing the human shaped phantom representing the patient during radiotherapy.
Figure 2 shows the radiation sensors taped onto the phantom to measure radiation dose.
Authors and Researchers featured:
Assoc. Prof. Dr Jeannie Wong is a medical physics lecturer at the Department of Biomedical Imaging, Faculty of Medicine, Universiti Malaya. Her interest is in radiation dosimetry, medical imaging and radiomics.
Assoc. Prof. Dr Ngie Min Ung is a medical physics lecturer at the Clinical Oncology Unit, Faculty of Medicine, Universiti Malaya. He obtained B. Biomed. Eng. and M. Med. Phys from UM, and received his PhD from the University of Western Australia. His interest is in radiotherapy physics, image-guided radiotherapy and radiation dosimetry.
Janatul Madinah Wahabi is a postgraduate student from the Department of Biomedical Imaging, Faculty of Medicine, Universiti Malaya. Her interest is in radiation dosimetry and quality assurance. She is also a radiotherapy medical physicist, working with the Ministry of Health, Malaysia.
Dr Ghafour Amouzad Mahdiraji is the Director of Flexilicate, a spin-off company from Universiti Malaya. He received his Ph.D. degree from the Universiti Putra Malaysia (UPM) in the field of Communications and Networks Engineering in 2009. His research interest is in specialty optical fibers and photonic sensors.
Copyedit: Michael Hoe Guang Jian (email@example.com)