The irradiation station on the Bronowice Cyclotron Middle. Ph.D. scholar Paulina Stasica-Dudek from the Institute of Nuclear Physics of the Polish Academy of Sciences presents the detector used to measure the standard of the proton beam. Credit score: IFJ PAN
Fashionable strategies of radiotherapy would combat most cancers extra successfully and safely if remedies could possibly be deliberate, considering the radiation high quality of the therapeutic proton beams. An achievement by physicists from the Institute of Nuclear Physics of the Polish Academy of Sciences in Cracow brings us nearer to this aim. The analysis is printed within the journal Physics in Medication & Biology.
In at this time’s medication, the connection is straightforward: if we would like most cancers therapy to be simpler and safer for the affected person, we normally must put money into higher irradiation tools, which, within the case of recent proton beams, means prices operating into tens of tens of millions of euros.
It seems, nonetheless, that an enchancment in therapy is achievable at a comparatively low value utilizing the tools already in operation, because of an answer introduced by a crew of physicists from the Cyclotron Middle Bronowice (CCB) of the Institute of Nuclear Physics of the Polish Academy of Sciences (IFJ PAN) in Cracow. The innovation, which might be utilized with the tools already in use, permits medical physicists, on the remedy starting stage, to confirm a parameter not beforehand exploited in scientific apply: the standard of the proton beam.
“Once we take the standard of the radiation beam under consideration, we’re in a position to decide the organic impact of radiation extra exactly and destroy most cancers cells extra successfully, whereas decreasing harm to wholesome tissues. Fashionable proton remedy planning software program permits this parameter to be taken under consideration.
“In practice, nobody does it, and one of the reasons for this is that until now, there has been no quick and simple method for experimental verification of radiation quality. We have shown that there is a practical solution to this problem that is cheap and easy to implement,” says Dr. Jan Gajewski (IFJ PAN).
Within the combat in opposition to most cancers cells, docs presently use irradiation primarily with photons, whereas solely a small variety of sufferers present process radiotherapy can profit from proton remedy. Two details are key right here. Firstly, when a beam of high-energy particles interacts with the mobile DNA molecules, it damages them, finally inflicting cell demise. Secondly, most cancers cells are typically extra delicate to radiation than wholesome, regular tissue cells that may effectively restore DNA harm.
How the therapeutic beam is run turns into essential. To keep away from later issues, resembling necrosis of wholesome tissue, the beam ought to work together with cells inside the tumor solely. That is, nonetheless, not doable, as a result of radiation should sometimes cross regular tissue to achieve the tumor.
On the similar time, all the quantity of the tumor with some surrounding wholesome tissue should be irradiated safely. It is because, in apply, if among the most cancers cells survive the therapy, the recurrence is usually extra harmful than the first tumor.
All radiotherapy remedies are fastidiously deliberate. The doctor first determines the extent of the cancerous lesion after which, utilizing specialised software program, plans a collection of therapy fractions sometimes spanning over weeks.
Physicians and physicists collectively exactly decide the instructions from which the tumor will probably be irradiated, the energies of the particles for use, the depth of the beam, in addition to irradiation length. Applicable therapy planning later makes it doable to ship a deadly dose of radiation to the tumor quantity whereas minimizing harm to wholesome tissue.
Nonetheless, planning alone isn’t sufficient. To be able to verify that the therapeutic dose conforms with the developed therapy plan, earlier than every therapy the medical physicist should measure the distribution of radiation doses the affected person will obtain.
(a) The MiniPIX Timepix3 detector with 300 µm-thick silicon sensor in Flex configuration (Advacam, Prague). Tailored from Stasica-Dudek et al (2025). CC BY 4.0. (b) A scheme (left) and a photograph (proper) of the experimental setup for the SOBP and IMPT subject measurements behind a strong RW3 phantom. (c) IMPT therapy plan ready for the CIRS head phantom (left), one of many fields recalculated for half of the pinnacle with indicated sensor place (center), and a photograph of the experimental setup for the measurements behind a heterogeneous phantom (proper). The sensor thickness within the center panel is to not scale. Credit score: Physics in Medication & Biology (2025). DOI: 10.1088/1361-6560/adcaf9
If the therapeutic beam consists of photons, all of them work together equally with the cells encountered within the affected person physique. Relating to the organic results of irradiation, physicists discuss in regards to the high quality of the radiation, which for photons would be the similar at every irradiated level. Protons behave otherwise when slowing down: initially, they lose little vitality, however the slower they’re, the extra quickly they lose vitality.
Consequently, the proton beam deposits most of its vitality on the finish of its path, at a well-defined depth contained in the affected person’s physique. The standard of such a proton beam is considerably totally different from that of a photon beam generally utilized in radiation remedy.
A bodily parameter known as linear vitality switch (LET) is used to explain the standard of radiation that influences the organic impact. It carries details about how a lot vitality a particle deposits over a set distance alongside its path and the way this loss varies with the vitality of the particle.
Making ready therapy plans considering the LET parameter isn’t an issue at this time. Sadly, present scientific apply lacks devices and measurement strategies to confirm the distribution of linear vitality switch immediately within the scientific atmosphere of radiotherapy.
Throughout analysis carried out at CCB utilizing a proton beam from the Proteus C-235 cyclotron, scientists from IFJ PAN used a commercially accessible Timepix3 detector to characterize the LET parameter. This small and comparatively easy-to-use detector is a results of the work of the Medipix3 Collaboration, fashioned in 2005 on the European Group for Nuclear Analysis (CERN) with a view to broad functions of technical options developed for particle monitoring in high-energy physics experiments.
The quite a few functions of the Timepix detectors are an exemplary demonstration of how pioneering physics analysis, seemingly disconnected from on a regular basis actuality, interprets into enhancements within the high quality of human life.
“The Timepix3 detector is provided with a 300 micrometer thick silicon sensor. Its readout electronics is a 256 by 256 pixel matrix, which permits the acquisition of single particle tracks. The response of every pixel will depend on the vitality it registers.
“This information, together with the track parameters, allows—using artificial intelligence methods—the identification of a single proton and the estimation of its LET parameter. The proposed methodology makes it possible to characterize LET under irradiation conditions compatible with therapeutic plans, which was a key challenge for us,” explains doctoral scholar Paulina Stasica-Dudek (IFJ PAN), first creator of the article.
Earlier than the strategy for measuring the standard of proton beams proposed by the Cracow physicists turns into on a regular basis apply, a technical hurdle must be overcome. Fashionable medical cyclotrons produce beams for scientific use, i.e., of excessive depth.
In the meantime, measurements carried out with Timepix detectors require low-intensity beams. It’s recognized, nonetheless, that this drawback might be solved by cyclotron producers with an acceptable replace to the software program controlling the depth of the beam produced by a cyclotron.
“For the first time, we can speak of a practically ready-to-implement method of measuring the quality of the radiation beam directly in proton therapy facilities. Its dissemination is a way to improve the efficiency and safety of modern proton therapy and more advanced irradiation methods using helium, carbon or oxygen ion beams,” says Dr. Antoni Ruciński, professor at IFJ PAN, summarizing the work of the crew.
Analysis on the methodology for measuring the standard of radiation beams was carried out beneath the LIDER XII grant from the Nationwide Centre for Analysis and Improvement (Poland).
Extra info:
Paulina Stasica-Dudek et al, Experimental validation of LET in intensity-modulated proton remedy with a miniaturized pixel detector, Physics in Medication & Biology (2025). DOI: 10.1088/1361-6560/adcaf9
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