Out of the numerous advanced imaging modalities, X-rays are the foremost in medical diagnosis and security. They help visualize an interior of the human body or examine items without opening them up. However, the most commonly used imaging materials known as X-ray scintillators – which perform the task of transforming x-rays to visible light for photography – are inorganic compounds. Although efficient, such materials are also costly, are toxic, and have complex processes of synthesis. But what if we could use organic materials instead? What’s more, this is what scientists are actively trying right now and with encouraging outcomes.
What Are Organic Radical Scintillators?
Organic radical scintillators are other types of the above materials in that they can also convert x-ray radiation to visible light. The only distinction is that these scintillators are made from organic non-metallic molecules and therefore are less cumbersome to manufacture, are environmentally friendly, and are inexpensive. These are also pliable, therefore, creating opportunities in developing large curved flexible x-ray imaging detectors may be possible.
One notable progress in the study is advanced open-shell organic radical scintillators. Unlike pure organic materials, however, these radicals contain an unpaired electron which imparts unique attributes to the materials, including improved light emission. Hence, they are very ideal in the field of x-ray imaging applications.
How Do They Work?
X-ray scintillators can be defined as material which absorbs high energy x-ray radiations and gives off that energy in the form of visible light. As X-rays are directed on to the scintillator, they cause the emission of electrons from its constituent atoms. These electrons are later bound to other atom nuclei generating electron-hole pairs. These pairs of electrons and holes eliminate one another over time and energy is released in the form of light. This light is then collected in order to form an image.
Historically, most organic materials could only achieve poor efficiencies with this process as they do not make full utilization of the energy from the x-rays. This insufficiency, however, has been solved by organic radical scintillators. They have the so-called doublet emission which enables them to extract use 100% of excitons which maximizes light emission enhancing scintillation performances of garnets.
The Role of Halogen Atoms
In the study, researchers produced and tested two types of organic radical scintillators, TTM-1Cz and TTM-1CzBr. The difference in the two is that TTM-1Cz contains no bromine atoms while TTM-1CzBr contains bromine Gilmour. Because bromine is a relatively large atom, TTM-1CzBr absorbs X rays better and is therefore more active in X-ray to light conversion than TTM-1Cz. Both materials were evaluated b y their X-ray-induced light emissivity, and their results were quite remarkable.
TTM-1CzBr scintillator was noted to not just have an improvement in X-ray absorption but also in the stability of the visible light emitted. Even with continuous exposure to X-ray for over 30 minutes, the material was found not to have suffered any performance degradation. Such durability positions it well for practical use in X-ray imaging ranging from medical applications to industrial uses.
Medical and Industrial Imaging Applications
These materials have one very bright application, which is in medical imaging x ray, in particular, micro x-ray computed tomography (micro-CT). The researchers have used the new scintinators to image high resolution objects including fibrous veins within a bamboo, which they were able to image. This suggests that these materials will find their way into next generation imaging devices, where high resolution imaging of tissues and organs will be needed.
Due to the fact that these scintillators are flexible, and therefore can be produced in large areas, will also enable the design of flexible X-ray screens. Such use will certainly see the light in industrial applications, where screens that bend along the profile of the object being imaged will give better performance.
What Comes After This?
This is only the first stage in the advent of the metal-free organic radical scintillators fully developed. The researchers have also set their centers on enhancing the light emission efficiency and new uses. After additional refinement, these materials will transform X-ray imaging within the framework of new approaches and replace expensive, rigid and bulky, traditional scintillators with cheap, light and flexible.
To conclude, organic radical scintillators are likely to be identified as the new generation of X-ray technology. New, efficient, durable and eco-friendly materials perfect for future medical and industrial imaging needs.
