The Digital Twin may well be the leading technology concept for the 21st century. Radiation oncology is well positioned to be a leader in healthcare adoption of this technology.
Radiotherapy has always been an area of rapid technological advancement in medicine. The basic device, the linear accelerator is essentially a particle accelerator that functions using the same physical principles of advanced research accelerators but is configured to work in the very limiting environment of healthcare. Including all the computer use and automation, radiotherapy is about as technologically advanced as any area of our world.
A recent area of technology development is an area called the Digital Twin. This is a relatively new concept, with its origins going back to the 1990s. It wasn’t until more recently, however, that the phrase Digital Twin was coined by John Vickers at NASA. A Digital Twin is a digital representation of a real-world object, system, or process. It is meant to be an identical digital representation of a device that will exist throughout the lifecycle of the real-world device. Its value is in the insights about building, operating, and decision making about the real-world device that are lacking without a digital representation. With the digital Twin, the device can be probed and investigated much more easily than the real device. This results in knowledge that would otherwise be difficult to obtain without the digital representation, and it is from this that the Digital Twin derives its value.
Digital twins are used in many industries, including heavy industries such as power generation and large buildings. It is related to the concept of Building Information Modelling (BIM) used in architecture and the construction industry. A Digital twin is also closely related to simple simulations, however Digital twins aim to study an entire environment, as opposed to a single process. In this way, valuable understanding about the complex system can be obtained and used in many useful ways. A key feature of the Digital Twin is that it must have a two-way information flow, meaning that to be a digital twin should be a living data system that truly represents the objects and system that we are interested in.
Healthcare is a rich environment for Digital Twins and there are numerous efforts in place to apply this technology to medicine. Some of the ideas involve using wearable devices to provide better models of diseases, predicting illness, and understanding treatment outcomes. Other applications are in the area of medical device manufacturing and drug risks, personalized medicine as well as many other areas.
For radiation oncology, computer simulations have long been an essential part of the process. Treatment planning systems, at their core, are computer simulations of the radiation treatment that the patient will undergo. Importantly, we do this before the treatment so that we can experiment with different beam configuration and orientations without harming the patient and gaining insights as to how to configure the linear accelerator optimally. Is it a Digital Twin? No. There are several reasons why.
First, we do not effectively feed data about the outcome of the treatment planning process back into the treatment planning system, meaning that the outcome of the simulation, other than producing a set of instructions for treating the patient, is lost information for the operator. Second, the treatment planning process is just a small part of the procedures used in the radiotherapy clinic. The entire process starts at the patient consult (or before) and ends when the patient finishes treatment and can no longer be followed, either because it is not needed, or the patient passes away. Lastly, there is much information about the clinic operation that affects the patient’s treatment, but it is not available to the treatment planning system: wait times, machine status, staff availability, and much more.
Radiotherapy has often been at the forefront of medical advancements; building useful digital representations of health care processes can and should be an integral part of our health system. Many have started building these systems, but it is still very early going. Can the radiotherapy community be a leader in this area? All the elements needed are in place; it is up to the community to take the lead.