31/08/2021
In the UK alone, 367,000 people are diagnosed with cancer every year. Since 1990, incidence rates for cancers have increased by 12%. Yet in the past 40 years, survival rates for cancer have doubled. This is mainly due to the development of technologies more capable of fighting cancer. One such area is radiotherapy; 27% of cancer patients undergo some form of radiotherapy during their treatment. This insight looks at how radiotherapy plans are devised and executed in a clinical setting, and at some of the companies filing patent applications in this area.
What is Radiotherapy?
Cancer cells occur when mutations in the genes of an otherwise normal cell lead to unregulated cell growth. Radiotherapy is the process of using radiation to “sterilise” these cells so that they cannot reproduce. During radiotherapy treatment, as radiation passes through the body, it can interact with an orbital electron in an atom and free it. This freed electron then directly or indirectly interacts with and damages the DNA of a cancer cell, stopping it from reproducing.
Unfortunately, the DNA of normal cells can also be damaged by this process, which may lead to the cell becoming cancerous. The probability of normal cells becoming cancerous scales approximately linearly with radiation dose received. As such, an important part of radiotherapy planning is not only to maximise the radiation dose received by cancerous cells, but also to reduce the dose to normal cells and particularly vulnerable areas.
X-ray and marking out cancerous regions
Designing a radiotherapy plan for a tumour typically begins with a computer tomography (CT) scan of the patient. This is obtained by taking multiple x-ray scans from around the patient’s body and combining them into a detailed, 3D image of the patient. This provides clinical scientists with a high quality image of the patient to analyse and identify cancerous regions. Unfortunately, this provides the first hurdle in cancer treatment: actual identification of cancer within the patient. Approximately 30% of CT scans result in a doctor misdiagnosing a patient as not having cancer when they in fact do (or vice versa).
One particular company seeking to deal with this problem is Kheiron Medical. Kheiron are developing machine learning technologies able to identify potential breast cancer risks in mammography images. Some of their patent applications relate to real-time analysis of x-ray scans to help determine if additional medical tests are required (UK patent application with publication No. GB2574659), a method of finding and measuring tumours in medical images (European patent application with publication No. EP3610456), and a method of converting data obtained from mammographic images (international patent application with publication No. WO2020109781).
When seeking to patent this kind of subject matter, there are some important issues applicants should be aware of.
Firstly, there are issues relating to patenting software. The EPO guidelines for examination state that “Computer programs are excluded from patentability… if claimed as such. However… the exclusion does not apply to computer programs having a technical character”. Any applicant seeking to protect software must ensure that their claims restrict their invention to having a specific technical character or feature. An example of a technical feature could be software that classifies digital images, videos, audio, or speech signals based on low-level features (for example, pixel attributes). Such software clearly solves the technical problem of classifying data.
Secondly, there are issues relating to patenting diagnostic technology and methods of treatment. An important provision in the European Patent Convention (Art. 53(c) EPC) states that European patents may not be granted for “methods for treatment of the human or animal body by surgery or therapy and diagnostic methods practised on the human or animal body; this provision shall not apply to products… for use in any of these methods”. For example, this means that whilst a patent should not be validly granted for a particular method of treating cancer (such as the process of radiotherapy itself) the manufacture of a device capable of performing that method (such as a particular machine to produce the radiation) could be. Patent claims seeking protect diagnostic technologies must therefore be carefully drafted to ensure they comply with European law.
Planning out radiotherapy plans
Once an image set of the patient with cancerous regions marked out is obtained, the next stage is to produce the radiotherapy plans. This typically involves a clinical scientist importing the patient image set into radiotherapy planning software. Within the radiotherapy planning software, the clinical scientist can mark out and designate other areas of the body (for example, marking out bones and lungs).
The clinical scientist then plans out mock radiotherapy plans, and uses the radiotherapy planning software to see how such a plan would affect the patient. Radiotherapy plans are typically designed with a set of clinical goals in mind. These goals might include minimum and maximum radiation limits to a tumour, or maximum radiation limits to nearby organs at risk (for example, the lungs in the case of treating breast cancer). Radiotherapy planning software provides a powerful tool for clinical scientists, by allowing radiotherapy plans to be better optimised to individual patients. Some radiotherapy planning software even allows the user to automate planning. By feeding in the clinical goals and patient image set, the software automatically optimises beam direction and power to achieve these goals.
One such planning software is RayStation developed by RaySearch Laboratories. They have patents and patent applications relating to optimising radiotherapy plans to minimize the dose to organs at risk (US patent No. US9468776), a method of generating radiotherapy plans for ion therapy (European patent application with publication No. EP3669940), and a method for automatically selecting a radiotherapy plan for a patient based on the availability of the resources required for that plan, i.e. the availability of treatment machines (US patent application with publication No. US2016/144198).
Patent protecting simulations in Europe is not always straightforward. Programs for computers, mathematical methods, and mental acts (which cover simulations in their purest form) are not considered inherently technical. To be eligible for a patent, an invention must be shown to provide a technical solution to a technical problem. One common way an applicant might try to show this is by linking their simulation to a physical entity in the real world. For example, using software to control the radiation dose given to a patient could provide this technical aspect. However, the recent European Patent Office Enlarged Board of Appeal decision G1/19 has indicated that a simulation does not need to have a direct link to reality in order to be patentable. This may allow for a broader range of patentable simulations in the coming years.
Performing the plan
The final stage of radiotherapy treatment is to apply the radiotherapy plan to the patient. Radiotherapy plans are delivered by a linear accelerator, or LINAC. Modern LINAC’s are able to produce x-ray and electron beams of different energies and shapes to effectively target cancerous regions whilst sparing healthy regions.
The total dose given to a patient is often divided into “fractions”. For example, rather than applying 40 Gy of radiation in a single session, instead the patient might receive 1 Gy a session for 40 sessions. The benefit in doing this comes from the different ways cancerous and healthy cells react to radiation. When exposed to radiation, healthy cells have a slightly better chance of surviving compared to cancerous cells. By splitting the dose into multiple sessions this effect is amplified, leading to less damage to the surrounding tissues. Ensuring that the radiotherapy plan is delivered to the patient in a safe and efficient manner is just as important as properly planning it.
Reddie & Grose has a wide breadth of experience in drafting and prosecuting patent applications relating to electronics, software, and medical technology related inventions. If you have products in the healthcare space, and are looking to obtain patent protection, or would like to discuss this or any of the content of this blog, please reach out to us.
This article is for general information only. Its content is not a statement of the law on any subject and does not constitute advice. Please contact Reddie & Grose LLP for advice before taking any action in reliance on it.
