The spatially and temporary localized energy deposited by pulsed protons and heavier ionsbeams gives rise to the emission of thermoacoustic waves [1], hereafter referred to as ionoacoustics. The initial pressure subsequent to the brief thermal heating of the irradiated volume is proportional to thedose and the medium properties, namely the mass density and the material-specific efficiency of...
Heavy ion particle therapy is a rapidly growing and potentially the most effective and preciseradiotherapy technique. However, the sharp dose gradients and very high doses in the distal ends make it extremely sensitive to range uncertainties, which remain one of its main limitations. In clinical practice, wide margins extending in the normal tissue are commonly used to guarantee the tumor...
The effective use of swift ion beams in cancer treatment (known as hadrontherapy) as well as an appropriate protection in manned space missions rely on the accurate understanding of energy delivery to cells damaging their genetic information [1]. The key ingredient characterizing the response of a medium to the perturbation induced by charged particles is its electronic excitation spectrum. By...
Monte Carlo Simulations of electrons in condensed matter require the knowledge of cross section data [1]. We present a simple procedure, which allows to generate a consistent set of cross sections for Monte Carlo simulations from parameters, which can be obtained from Quantum Chemistry calculations with standard software as for example the program package Gaussian.
We show how the cross...
In radiotherapy treatments, the Radiobiological Effectiveness of Radiation (RBE) is customary assumed to be proportional to the absorbed dose. We have shown in a recent publication [1], that induced damage at the molecular level in water, in terms of induced molecular dissociations, by a 6MV X-ray beam generated by a clinical LINAC accelerator, is always proportional to the induced ionisation...
The mysterious differential effectiveness of ultra-high dose rate (UHDR) irradiations, returning a protective effect on normal tissues for same antitumor efficacy as compared to conventional dose rates, the so-called FLASH effect, observed in numerous preclinical experiments, triggered in the last 3-4 years an exponentially growing number of biophysical modeling works attempting to investigate...
The main rationale for using protons in cancer treatment is based on the highly conformal dose distribution and normal tissue spearing compared to conventional radiotherapy. One of the main limits of proton therapy is the particle range uncertainty due to patient setup, dose calculation and imaging. A mispositioning potentially translates into an under-dosage of the tumor as well as an...
Purpose: An innovative detector based on thin silicon UFSD detectors was developed and characterized by the medical physics group of the University and INFN-Torinofor single ion discrimination and ion counting in a therapeutic particle beam.
Materials and Methods: Thin silicon sensors were developed, characterized and used in a prototype detector aiming at discriminating and counting single...
Boron Neutron Capture Therapy (BNCT) is a radiotherapy that consists in patient irradiation with low energy neutrons after the administration of a tumour-targeting borated drug [1]. The thermal neutron capture in 10B generates two high-LET, short-range charged particles that cause non-reparable damages to the cell where the reaction takes place. Provided a suitable tumour-to-normal tissue...
Alpha emitters hold great promise to improve ligandtherapy or Targeted Alpha Therapy (TAT), where an alpha emitter is attached to a biological tracer. The tracer is injected into the blood stream of a cancer patient and accumulates over time in the cells with the targeted expression, e.g.cancer cells. As alpha particles have a relative high Linear Energy Transfer (LET), it typically causes...
The cyclotron-based production of radionuclides for medicine is one of the research activities carried out in the framework of the SPES (Selective Production of Exotic Species) project at the Legnaro National Laboratories of the National Institute for Nuclear Physics (INFN-LNL). SPES aims at the construction of an advanced ISOL (Isotope Separation On-Line) facility to produce re-accelerated...
Using unconventional radionuclides for cancer treatment has been gaining popularity in recent years thanks to the remarkable results from the clinical studies with 177Lu, 223Ra and 225Ac1–3. TRIUMF launched a campaign to produce 225Ac from 232Th spallation4. Benefiting from this program, several other interesting alpha-emitters are co-produced, including 213Bi, 227Th, and 212Pb, which we have...
The interaction of biomolecules with positron is of special interest apropos to positron emission tomography (PET) scans [1,2]. Using positron emitters in PET scans has aided the early detection of cancer and brain disorders. Furthermore, this technique has also been considered an alternative to ion beam cancer treatments for dosimetry purposes. The cross-section resulting from the interaction...
In this work we present a method for calculating relativistic electron scattering with nuclei, atoms and molecules including the temperature dependence. In particular, we focus on the mean-field approximation of the Dirac equation for many-fermion systems and its self-consistent numerical solutions, which are obtained by using either radial mesh or Gaussian basis sets. The former approach is...
Charged particle radiotherapy (CPT) with helium and deuterium was first used seventy years ago by Lawrence and Tobias [1]. CPT provides a better physical dose distribution than conventional X-ray treatment with a well-defined high dose region known as the Spread-Out Bragg Peak (SOBP) which can be positioned in the tumour with much lower doses to the surrounding tissues. This higher therapeutic...
Microdosimetry provides information about the pattern of energy deposition in biological targets that be correlated with biological effects and may be useful in planning and conducting radiation therapy. The methodology is clearly relevant to charged particle beam therapy but can provide relevant information also to BNCT, targeted internal emitters and conventional photon therapy.
In...
In this talk, I will give an overview of the applications of nanodosimetry in particle therapy treatment planning [1]. My talk will summarize the underlying concepts of nanodosimetry and describe the development and current status of nanodosimetric detector technology. I will also give an overview of Monte Carlo track structure simulations that provide nanodosimetric parameters for proton and...
About 80% of the energy absorbed in cells exposed to high-energy ionizing radiation (IR), produces firstly ions and secondary electrons. These latter posse the largest portion of the deposited energy (E), with an initial energy distribution lying essentially below 30 eV and peaking around 9-10 eV. Although some low-energy (E<20 eV) electrons (LEEs) can further ionize biological tissues, they...
The interaction of low-energy electrons (LEEs) with DNA plays a significant role in the mechanisms leading to biological damage induced by ionizing radiation, particularly in radiotherapy, and its sensitization by chemotherapeutic drugs and nanoparticles [1]. Plasmids constitute the form of DNA found in mitochondria and appear as a suitable model of genomic DNA [2]. In a search for the best...
The interaction of swift charged particles (either ion beams or energetic electrons) with condensed-phase materials underlies many biomedical applications of radiation. Energetic proton or carbon ion beams are used in the advanced radiotherapy technique of hadrontherapy, and their nanometric track-structure is defined by the ejection and propagation of secondary electrons [1]. Energetic...
Proton irradiation of DNA is of utmost importance for many fields, from understanding radiation damage in space and Earth to medical applications for cancer treatment. Computer simulations are highly valuable tools for understanding such process, and among these, ab initio simulations employing Real Time - Time Dependent Density Functional Theory (RT-TDDFT) allow to obtain an extremely...
In this talk I will provide a general overview on the role played by low energy electrons in DNA damage.First, I willbriefly discussexperimental findings and theoretical results hand in hand with the aim of describing thephysics and chemistry that occurs during the process of radiation damage, from the initialstages of electronic excitation, through the inelastic propagation of electrons in...
Despite a vast accumulated basic knowledge in irradiating single cells and tissues, medical radiotherapy of cancer is still based on the application of simple empirical models, with little or no reference to the microscopic complexity of DNA damage and molecular repair pathways. In cell irradiation experiments, the amount of radiation-induced DNA damage is found to be systematically...
Radiation therapy remains a fundamental tool for cancer treatment, but selective dose deposition within a targeted-tumor, while sparing surrounding structures, remains a challenge. This objective can be achieved by loading the tumor with high-Z elements prior delivery of radiation therapy. Synchrotron sources are ideal sources since they provide high-intensity and tunable monochromatic X-rays...
To improve the efficacy of radiotherapy one of the objective is to increase the dose delivered to the tumour while sparing the surrounding healthy tissues. The strategy we have used consists in loading the tumorwith high-Z elements such as metallic nanoparticles in combination with low energy radiations. Indeed, for low energy radiations (keVrange) the absorption coefficient of heavy elements...
Nanostructured materials are widely being studied as radiosensitizers to increase the efficacy of radiation therapy in the treatment of cancer. Here we present recent results for enhanced cell killing for in-vitro irradiation by protons of malignant prostate and breast epithelial cells treated with gold nanoparticles in an energy range approaching the Bragg peak.Theexperiments were conducted...
Monte Carlo (MC) radiation transport codes for charged particles, including electrons, protons, light and heavy ions, provide detailed information about interaction types, spatial and temporal distributions of energy depositions, as well as radical species produced in the early physical and chemical states of radiation action with matter. This information allows to investigate the biological...
The currently established imaging modality used for treatment planning in ion therapy is x-ray computed tomography (CT). Due to the non-bijective relation between the photon attenuation coefficient, reconstructed with x-ray CT, and the relative stopping power (RSP) required for ion therapy treatment planning, RSP errors of about 3% may occur [1]. The use of ion CT promises to yield improved...
Purpose: The dose computation in the proton treatment planning system (TPS) is based on the proton relative stopping power normalized to liquid water (RSP) distribution in the target volume. Presently, the RSP maps are extracted from x-ray computed tomographies (xCT) of the patient. Namely, the photon attenuation coefficients (CT Hounsfield Units – HU), are translated into RSP values using...
Pencil beam scanning (PBS) is the most common delivery techniquein proton therapy nowadays because of its high potential to reach gooddose homogeneity to the target and organs at risk (OAR) sparing. It ispossible to modulate each beam in terms of position, intensity andenergy to reach the best plan quality. In case of static lesions, thequality of the dose distribution can be more easily...