Purpose: Treatment planning in proton therapy uses a generic value for the relative biological efficiency (RBE) of 1.1 throughout the spread-out Bragg peak (SOBP) generated. In this article, we report on the variation of the RBE with depth in the SOBP of the 76- and 201-MeV proton beams used for treatment at the Institut Curie Proton Therapy Center in Orsay.
Methods And Materials: The RBE (relative to (137)Cs γ-rays) of the two modulated proton beams at three positions in the SOBP was determined in two human tumor cells using as endpoints clonogenic cell survival and the incidence of DNA double-strand breaks (DSBs) as measured by pulse-field gel electrophoresis without and with enzymatic treatment to reveal clustered lesions.
Results: The RBE for induced cell killing by the 76-MeV beam increased with depth in the SOBP. However for the 201-MeV protons, it was close to that for (137)Cs γ-rays and did not vary significantly. The incidence of DSBs and clustered lesions was higher for protons than for (137)Cs γ-rays, but did not depend on the proton energy or the position in the SOBP.
Conclusions: Until now, little attention has been paid to the variation of RBE with depth in the SOBP as a function of the nominal energy of the primary proton beam and the molecular nature of the DNA damage. The RBE increase in the 76-MeV SOBP implies that the tumor tissues at the distal end receives a higher biologically equivalent dose than at the proximal end, despite a homogeneous physical dose. This is not the case for the 201-MeV energy beam. The precise determination of the effects of incident beam energy, modulation, and depth in tissues on the linear energy transfer-RBE relationship is essential for treatment planning.
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http://dx.doi.org/10.1016/j.ijrobp.2010.09.003 | DOI Listing |
J Appl Clin Med Phys
December 2024
Department of Radiation Oncology, Lynn Cancer Institute, Boca Raton Regional Hospital, Baptist Health South Florida, Boca Raton, Florida, USA.
Purpose: A novel proton beam delivery method known as DynamicARC spot scanning has been introduced. The current study aims to determine whether the partial proton arc technique, in conjunction with DynamicARC pencil beam scanning (PBS), can meet clinical acceptance criteria for bilateral head and neck cancer (HNC) and provide an alternative to full proton arc and traditional intensity-modulated proton therapy (IMPT).
Method: The study retrospectively included anonymized CT datasets from ten patients with bilateral HNC, all of whom had previously received photon treatment.
J Med Signals Sens
November 2024
Department of Medical Physics, School of Medicine, Isfahan University of Medical Sciences, Isfahan, Iran.
Phys Med Biol
December 2024
Medical Physics, EBG MedAustron GmbH, Marie-Curie-Str. 5, Wiener Neustadt, 2700, AUSTRIA.
To investigate the impact of the positioning of plane-parallel ionization chambers in proton beams on the calculation of the chamber-specific factor fand, hence, the beam quality correction factor k. Approach: Monte Carlo simulations were performed to calculate the chamber-specific factor fin monoenergetic proton beams for six different plane-parallel ionization chambers while positioning the chambers with a) their reference point and b) their effective point of measurement accounting for the water equivalent thickness of the entrance window. Main results: For all ionization chamber models investigated in this study, the difference in fbetween both positioning approaches was larger for steeper dose gradients and bigger differences between the geometrical thickness and water-equivalent thickness of the entrance window.
View Article and Find Full Text PDFSci Rep
December 2024
Centro de Láseres Pulsados, Building M5, Science Park, Calle Adaja 8, 37185, Villamayor, Salamanca, Spain.
Laser-Plasma ion acceleration is acquiring importance on a daily basis due to incipient applicability in certain research fields. However, the energy and divergence control of these brilliant sources can be considered a bottleneck in the development of some applications. In this work, we present the commissioning of a compact proton beamline based on a triplet of quadrupoles dedicated to focus and collect short and energetic pulses, open to the user community.
View Article and Find Full Text PDFAppl Radiat Isot
November 2024
Nuclear Physics Division, Bhabha Atomic Research Centre, Mumbai, 400 085, India.
The cumulative yield of the fission products within the mass range of 83-117 and 123-153 have been measured in the 6.61and 10.92 MeV quasi-mono-energetic neutron-induced fission of U by using an off-line γ-ray spectrometric technique.
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