S. Lo Nigro

A 62 MeV proton beam for the treatment of ocular melanoma at Laboratori Nazionali del Sud-INFN (CATANIA)

At the INFN Laboratori Nazionali del Sud in Catania (Italy) the first Italian protontherapy facility, named CATANA (Centre di AdroTerapia e Applicazioni Nucleari Avanzate) has been realized in collaboration with the University of Catania. It is based on the use of the 62 MeV proton beam delivered by the K = 800 superconducting cyclotron installed and working at LNS since 1995. The facility is mainly devoted to the treatment of ocular diseases like uveal melanoma. A beam treatment line in air has been realized together with a dedicated positioning patient system. The facility is in operation since the beginning of 2002 and 52 patients have been successfully treated up to now. The main features of CATANA together with the clinical and dosimetric features will be extensively reported; particularly, will be described the proton beam line, that has been entirely realized at LNS, with all its elements, the experimental transversal and depth dose distributions of the 62 MeV proton beam obtained for a final collimator of 25 mm diameter and the experimental depth dose distributions of a modulated proton beam obtained for the same final collimator. Finally, the clinical results over one year of treatments, describing the features of the treated diseases will be reported.

Cellular and molecular effects of protons: Apoptosis induction and potential implications for cancer therapy

Due to their ballistic precision, apoptosis induction by protons could be a strategy to specifically eliminate neoplastic cells. To characterize the cellular and molecular effects of these hadrons, we performed dose-response and time-course experiments by exposing different cell lines (PC3, Ca301D, MCF7) to increasing doses of protons and examining them with FACS, RT-PCR, and electron spin resonance (ESR). Irradiation with a dose of 10 Gy of a 26,7 Mev proton beam altered cell structures such as membranes, caused DNA double strand breaks, and significantly increased intracellular levels of hydroxyl ions, are active oxygen species (ROS). This modified the transcriptome of irradiated cells, activated the mitochondrial (intrinsic) pathway of apoptosis, and resulted in cycle arrest at the G2/M boundary. The number of necrotic cells within the irradiated cell population did not significantly increase with respect to the controls. The effects of irradiation with 20 Gy were qualitatively as well as quantitatively similar, but exposure to 40 Gy caused massive necrosis. Similar experiments with photons demonstrated that they induce apoptosis in a significantly lower number of cells and in a temporally delayed manner. These data advance our knowledge on the cellular and molecular effects of proton irradiation and could be useful for improving current hadrontherapy protocols.

Mass and charge identification of fragments detected with the Chimera Silicon-CsI(Tl) telescopes

Abstract Mass and charge identification of charged products detected with Silicon–CsI(Tl) telescopes of the Chimera apparatus are presented. An identification function, based on the Bethe–Bloch formula, is used to fit empirical correlations between Δ E and E ADC readings, in order to determine, event by event, the atomic and mass numbers of the detected charged reaction products prior to energy calibration.

Dosimetric characterization of silicon and diamond detectors in low-energy proton beams.

The dosimetric behaviour of a Scanditronix p-type silicon diode and a PTW natural diamond detector was studied in low-energy proton beams in the 8.3-21.5 MeV range. The properties investigated were linearity, reproducibility, dose rate dependence, energy and linear energy transfer (LET) dependence. The influence of detector thickness on the results of depth dose measurements was also demonstrated. A Markus parallel plate ionization chamber was used for reference dosimetry. Silicon diode and diamond detectors showed linearity at therapeutic dose level, reproducibility better than 1% (1sigma) and sensitivity variation with dose rate and proton energy.

Monte Carlo Studies of a Proton Computed Tomography System

Proton therapy is a precise forms of radiation therapy that makes use of high energy proton compared to the conventional, more commonly used and less precise x-ray and electron beams. On the other hand, to fully exploit the proton therapy advantages, very accurate quality controls of the treatments are required. These are mainly related to the dose calculations and treatment planning. Actually dose calculations are routinely performed on the basis of X-ray computed tomography while a big improvement could be obtained with the direct use of protons as the imaging system. In this work we report the results of Monte Carlo simulations for the study of an imaging system based on the use of high energy protons: the proton computed tomography (pCT). The main limitation of the pCT and the current adopted technical solutions, based on the use of the most likely path (MLP) approximation are illustrated. Simulation results are compared with experimental data obtained with a first prototype of pCT system tested with 200 MeV proton beams available at the Loma Linda University Medical Center (LLUMC) (CA).

Light response and particle identification with large CsI(TI) crystals coupled to photodiodes

The light response of large CsI(TI) crystals supplied by various companies and coupled to photodiodes has been investigated. Energy resolution measurements and Z = 1 isotopic identification using the two gates method have been performed with in-beam experiments.

Decay constant for spontaneous fission of 238U and 232Th

Abstract A measurement of the decay constant λ f for spontaneous fission of 238 U has been carried out with the glass sandwich technique by using a thin layer of UF 4 . Both the fragments of the spontaneous fission events have been made visible. From the fission track density registered after five different times of exposure from 8 to 17 months, the value λ f = (7.2±0.2) × 10 −17 y −1 has been obtained. Measurements performed on 232 Th allowed to deduce the value λ f −20 y −1 .

Excitation energy dependence of photofissility in preactinide nuclei

SummaryThe dependence on excitation energyE* of photofissilityPf of preactinide nuclei is examined. An accurate evaluation ofE*, and of mass and charge configurations of the compound nucleus for (100÷300) MeV photons is calculated by means of an intranuclear-cascade model. It is found that, at high excitation energy, is no longer a correct variable to describe the excitation energy dependence ofPf.RiassuntoViene esaminata la dipendenza dall’energia di eccitazioneE* della foto-fissionabilitàPf di nuclei preactinidi. Per mezzo di un modello di cascata intranucleare, sono accuratamente valutatiE*, e le configurazioni di massa e carica dei nuclei composti formati nell’interazione di fotoni d’energia (100÷300) MeV con Au e Bi. Come risultato viene trovato che, ad alte energie di eccitazione, non è più una variabile corretta per descrivere la dipendenza diPf dall’energia di eccitazione.РезюмеИсследуется зависимость фотоделимостиPf от энергии возбужденияE* в ядрах предактинидов. С помощью модели внутриядерного каскада аккуратно вычисляютсяE*, и конфигурации массы и заряда составных ядер, образованных при взаимодействии фотонов с энергиями (100÷300) МэВ с Au и Bi. Получено, что при высоких энергиях возбуждение величина больше не является корректной переменной для опиоания завиоимости фотоделимостиPf от энергии возбуждения.

GRAAL: a polarized γ-ray beam at ESRF☆

The GRAAL facility produces a highly polarized gamma-ray beam by Compton scattering of laser photons on the electrons of the European Synchrotron Radiation Facility (ESRF) at Grenoble. Preliminary results have been obtained with the LAGRANGE detector showing its excellent performances.

Fission yields of 28 elements by bremsstrahlung photons of 1000 MeV maximum energy

Abstract The photofission cross section per equivalent quantum of 28 elements from Bi to Fe has been measured at 1000 MeV bremsstrahlung maximum energy. The fission fragments have been detected by means of the glass sandwich technique. Information is deduced on the dependence of the nuclear fissility on Z2/A.