Shot of science: X-rays in our daily lives and at Lonza Drug Product Services
X-rays are a form of electromagnetic radiation, which uses are not limited to hospitals. Let’s explore their implementation in characterizing pharmaceutical products and packaging.
Light is electromagnetic radiation consisting of waves of different energies and frequencies. At some wavelengths, light appears visible to our eyes, whereas other wavelengths, such as the infrared, ultraviolet and X-rays, remain undetected by our vision.
X-rays, first discovered by Wilhelm Conrad Röntgen in 1985, have relatively short wavelength ranging from one hundredth of a nanometer to ten nanometers. Thanks to their short wavelength, X-rays are able to pass through various materials including human tissues. This is where familiarity with X-rays originates; most people have encountered them in hospitals, emergency rooms or at the dentist’s office.
Shadow play
Imagine that you place your hand in front of a flashlight — your hand will cast a shadow on the wall behind it. Creating an image with X-rays can be compared to this process. X-rays can pass through many materials. However, if the material or tissue contains a dense atom such as iodine or calcium, the rays are absorbed and thereby create a shadow on the X-ray film or a detector.
The resulting images of contrast therefore depend on the X-ray density and reveal crucial information about the structure of the material or tissue. This is also the reason, why are patients often injected with a contrasting agent prior to a CT scan — to increase the contrast of the shadow images.
Going 3D
The 2D images of human body are of great use in medicine; doctors can easily recognize details with millimeter resolution and distinguish between bones and softer tissues such as tendons and muscles.
To obtain three-dimensional information, X-ray images from various angles need to be taken at the same time. This technique, called computerized tomography (CT), creates cross-sectional images of the imaged material.
Dr. Pascal Chalus is a senior principal scientist in forensic chemistry at Lonza Drug Product Services with over 10 years of experience in various spectroscopy and imaging techniques. His focus also lies on the use of a micro-CT, a technique allowing for observing small samples in 3D with the aid of X-rays.
“CT in hospitals and our micro-CT instrument work on the same principle. The instrument takes classical X-ray shadow images all around the sample. Afterwards, with the aid of a computer, we make a triangulation of each point of the sample. We can trace the movement of each spot on the detector and create the exact 3D position,” explains Chalus.
Clinical CTs and the micro-CT used in Lonza are fairly similar in parameters. Both allow for creating a 3D image of the sample (or a patient), they use similar copper-based X-ray source of 60–100 kV, the intensity is 100–190 mA.
The only differences between these two techniques are the distance of the sample and the detector (these techniques will have different magnifications and resolution), and the instrument set-up. Since patients cannot stay still while being rotated, the X-ray source and the detector has to rotate around them while they lie still. Micro-CT instrument has the detector and the source fixed, while the sample rotates inside.
CT at Lonza
“In hospitals, patients are injected with a contrast agent to improve imaging. We often also use contrast agents for our technical samples, for instance if we want to observe a liquid in the needle of the syringe. By adding iodine into the solution, we raise the contrast and are able to see the liquid inside of the needle even through the metal or through the glass of the syringe,” explains Chalus.
Syringes often come with in pens or auto-injector devices. Micro-CT also allows for characterizing these, e.g., checking proper needle position in the needle shield or the conus of the glass.
Other potential uses of X-ray in technical development imaging include the characterization of tablets. Tables are powders pressed into a compact form. If we compress too little, the tablets might be too fragile to transport. Compress too hard and your tablets might develop micro cracks, which could cause them to split after moisture gets inside after a longer storage. Micro-CT can detect these cracks easily and even help to check the regularity and thickness of the tablet’s coating, or homogeneous distribution of the active pharmaceutical ingredient.
Another application is the assessment and investigation of potential packaging defects, for instance the closure of vials and stoppers, or even structure of lyophilized contents, the so called lyophilisation cake, inside of the vials.
Unexpected uses of CT
X-ray imaging is not limited to clinical or pharmaceutical use. This versatile technique can help in discovering the origins of jewelry, for instance pearls or gemstones. Moreover, geologists use it to determine structure of rocks, workers can control for micro-cracks in concrete-based buildings.
CT scans can help to guide workers on cutting trees into planks, check for the fat migration within chocolate bars stored at too high or too low temperatures, control proper layering of caramel and chocolate and air bubble distribution in ice cream bars, or even ensure that the lyophilized coffee powder will dissolve well and create a nice creamy foam.
CT can even help in cooking and determine the correct temperature and cooking time for the perfect French fry.
