Projetc ID: NdS-II/SP/0292/2024/01
Name of the programme: Science for the Society
Project title: Optimization of irradiation methods and dosimetric characteristics of the FLASH proton beam
Principial Investigator: dr inż. Marzena Rydygier
Project Duration: 29.03.2024 – 28.03.2027
Budget: 1 000 000 PLN
Project description
Cancer is the second most common cause of death in Poland and one of the most common worldwide. Therefore, combating cancer is one of society’s greatest health care challenges. Radiation therapy, along with surgical intervention and chemotherapy, is one of the primary methods of treating cancer. It is a branch of medicine that uses ionizing radiation to treat cancer. Depending on the type of radiation used, we distinguish between photon radiation therapy, which is commonly used, and proton radiation therapy, which is under development. The main advantage of proton therapy over photon radiotherapy is due to the physical properties of the proton beam and the nature of its interactions with matter. In the case of photons, the process of energy deposition in the patient’s body results in a region of dose buildup (so-called build-up), beyond which there is a gentle decrease in dose. A proton beam, on the other hand, penetrating the patient’s body, deposits its energy at the end of its range, creating a characteristic Bragg peak. This allows the radiation to be delivered mainly to the cancerous tumor area, while sparing the healthy tissues surrounding the lesion.
In general, the use of proton beams in radiotherapy is justified by two main factors. The first is the low entrance dose and the dose decreasing to practically zero in the distal region of the depth dose distribution, which allows more effective protection of healthy tissues surrounding the treated volume, located in front of and behind the tumor. Second, much larger lateral and distal dose gradients (smaller beam penumbras), allow conformal dose distributions to be achieved. Clinically, these properties of protons allow up to a triple reduction in absorbed dose in healthy tissues compared to the use of photons in 3D-CRT, although current intensity-modulated rotational techniques used in photon radiotherapy (IMRT, V-MAT) mitigate the difference between these modalities. Reduction of absorbed dose in healthy tissues is also of particular importance in radiotherapy of pediatric patients, often improving patient comfort. In addition, exposure of healthy tissues during radiotherapy for pediatric patients, who are expected to live a long time after irradiation, may increase the likelihood of secondary cancers.
The advantages of proton radiotherapy can be further enhanced by using a beam in the FLASH (FLASH proton therapy) modality, with ultra-high dose rates. Over the past few years, the impact of FLASH radiotherapy has been the subject of preclinical and clinical studies. Preliminary results from in vivo experiments indicate the potential presence of beneficial biological effects, in the form of less radiotherapy toxicity and sparing of healthy tissues surrounding the tumor area when therapeutic doses are deposited in the tumor. Potentially, this property allows for dose escalation in the tumor-affected area, while limiting the impact of radiation on healthy tissues. Clinically, FLASH has the potential to significantly reduce post-treatment complications, improve accessibility of radiation therapy to patients, and reduce treatment costs, due to a significant increase in the number of patients treated. This is due to significantly shorter treatment durations and the ability to administer very few, even single fractions of treatment.
The CCB of the IFJ PAN is equipped with a modern isochronous cyclotron, C-230, allowing the acceleration of protons up to an energy of 230 MeV. The possibility of using a FLASH proton beam at the CCB therapeutic station, i.e. operating in ultra-high dose rate mode, requires the delivery of a beam with an intensity of at least 40 Gy/s. Current operating parameters of the accelerator and proton beam line elements in clinical mode do not allow to achieve the required dose rates. It is necessary to optimize the individual components of the accelerator system and the beamline parameters in order to maximize the transmission from the cyclotron to the therapy room. In tandem, optimization of the beam delivery system parameters must be followed by improvement of dosimetry methods that allow reliable dose measurements for modified system parameters. The ongoing project “Optimization of Irradiation Methods and Dosimetric Characterization of the FLASH Proton Beam” of a medical physics and accelerator physics R&D nature, aims to enhance scientific excellence and support innovation processes in the field of proton radiotherapy. The project develops techniques for delivering FLASH proton beams at high dose rates to therapeutic sites and develops radiation dosimetry methods that require great precision and reliable response of radiation detectors over a wide dynamic range. Proton beam dosimetry in FLASH mode is a complex issue, as it is necessary to operate dosimetry devices often at the limit of their technical capabilities. The result of the project will be a dosimetrically and spatial-time structure characterized scanning proton beam in FLASH technique, which will strengthen the ability to support innovation and broaden the range of offerings to potential customers of the technology for scientific research and development work not only in the field of physics but also radiobiology, animal experiments in the regime of ultra-high dose rates.