The only method for in vivo dose delivery verification in proton beam radiotherapy in clinical use today is positron emission tomography (PET) of the positron emitters produced in the patient during ...irradiation. PET imaging while the beam is on (so called beam-on PET) is an attractive option, providing the largest number of counts, the least biological washout and the fastest feedback. In this implementation, all nuclides, independent of their half-life, will contribute. As a first step towards assessing the relevance of short-lived nuclides (half-life shorter than that of 10C, T1/2 = 19 s) for in vivo dose delivery verification using beam-on PET, we measured their production in the stopping of 55 MeV protons in water, carbon, phosphorus and calcium The most copiously produced short-lived nuclides and their production rates relative to the relevant long-lived nuclides are: 12N (T1/2 = 11 ms) on carbon (9% of 11C), 29P (T1/2 = 4.1 s) on phosphorus (20% of 30P) and 38mK (T1/2 = 0.92 s) on calcium (113% of 38gK). No short-lived nuclides are produced on oxygen. The number of decays integrated from the start of an irradiation as a function of time during the irradiation of PMMA and 4 tissue materials has been determined. For (carbon-rich) adipose tissue, 12N dominates up to 70 s. On bone tissue, 12N dominates over 15O during the first 8-15 s (depending on carbon-to-oxygen ratio). The short-lived nuclides created on phosphorus and calcium provide 2.5 times more beam-on PET counts than the long-lived ones produced on these elements during a 70 s irradiation. From the estimated number of 12N PET counts, we conclude that, for any tissue, 12N PET imaging potentially provides equal to superior proton range information compared to prompt gamma imaging with an optimized knife-edge slit camera. The practical implementation of 12N PET imaging is discussed.
Precision data are presented for the break-up reaction, H2(p→,pp)n, within the framework of nuclear-force studies. The experiment was carried out at KVI using a polarized-proton beam of 190 MeV ...impinging on a liquid-deuterium target and by exploiting the detector, BINA. Some of the vector-analyzing powers are presented and compared with state-of-the-art Faddeev calculations including three-nucleon forces effect. Significant discrepancies between the data and theoretical predictions were observed for kinematical configurations which correspond to the H2(p→,He2)n channel. These results are compared to the H2(p→,d)p reaction to test the isospin sensitivity of the present three-nucleon force models. The current modeling of two and three-nucleon forces is not sufficient to describe consistently polarization data for both isospin states.
High precision cross-section data of the deuteron–proton breakup reaction at 130 MeV deuteron energy are compared with the theoretical predictions obtained with a coupled-channel extension of the CD ...Bonn potential with virtual Δ-isobar excitation, without and with inclusion of the long-range Coulomb force. The Coulomb effect is studied on the basis of the cross-section data set, extended in this work to about 1500 data points by including breakup geometries characterized by small polar angles of the two protons. The experimental data clearly prefer predictions obtained with the Coulomb interaction included. The strongest effects are observed in regions in which the relative energy of the two protons is the smallest.
Highlights ► We review immunogenicity and safety data of Quinvaxem® . ► We present data from four clinical trials and a post-marketing surveillance study. ► The key role of Quinvaxem® in EPI ...vaccination programs is discussed. ► We present Uniject® , a simplified, prefilled injection system. ► Quinvaxem® in Uniject® presentation should aid vaccination programs achieve more.
•A Multiple Coulomb scattering of a proton causing image blurring is studied.•A phantom with several tissue surrogates is irradiated.•A proton scattering angle is calculated using direction and ...position information.•Clinically relevant proton beam energies were studied.•Using proton direction gives factor 2 less statistics than proton position.
Proton radiography is a novel imaging modality that allows direct measurement of the proton energy loss in various tissues. Currently, due to the conversion of so-called Hounsfield units from X-ray Computed Tomography (CT) into relative proton stopping powers (RPSP), the uncertainties of RPSP are 3–5% or higher, which need to be minimized down to 1% to make the proton treatment plans more accurate.
In this work, we simulated a proton radiography system, with position-sensitive detectors (PSDs) and a residual energy detector (RED). The simulations were built using Geant4, a Monte Carlo simulation toolkit. A phantom, consisting of several materials was placed between the PSDs of various Water Equivalent Thicknesses (WET), corresponding to an ideal detector, a gaseous detector, silicon and plastic scintillator detectors. The energy loss radiograph and the scattering angle distributions of the protons were studied for proton beam energies of 150MeV, 190MeV and 230MeV. To improve the image quality deteriorated by the multiple Coulomb scattering (MCS), protons with small angles were selected. Two ways of calculating a scattering angle were considered using the proton’s direction and position.
A scattering angle cut of 8.7mrad was applied giving an optimal balance between quality and efficiency of the radiographic image. For the three proton beam energies, the number of protons used in image reconstruction with the direction method was half the number of protons kept using the position method.
The quality of cancer treatment with protons critically depends on an accurate prediction of the proton stopping powers for the tissues traversed by the protons. Today, treatment planning in proton ...radiotherapy is based on stopping power calculations from densities of X-ray Computed Tomography (CT) images. This causes systematic uncertainties in the calculated proton range in a patient of typically 3-4%, but can become even 10% in bone regions 1,2,3,4,5,6,7,8. This may lead to no dose in parts of the tumor and too high dose in healthy tissues 1. A direct measurement of proton stopping powers with high-energy protons will allow reducing these uncertainties and will improve the quality of the treatment. Several studies have shown that a sufficiently accurate radiograph can be obtained by tracking individual protons traversing a phantom (patient) 4,6,10. Our studies benefit from the gas-filled time projection chambers based on GridPix technology 2, developed at Nikhef, capable of tracking a single proton. A BaF sub(2) crystal measuring the residual energy of protons was used. Proton radiographs of phantom consisting of different tissue-like materials were measured with a 30x30 mm super(2) 150 MeV proton beam. Measurements were simulated with the Geant4 toolkit.First experimental and simulated energy radiographs are in very good agreement 3. In this paper we focus on simulation studies of the proton scattering angle as it affects the position resolution of the proton energy loss radiograph. By selecting protons with a small scattering angle, the image quality can be improved significantly.
A set of differential cross-section data of the
1
H
(
d
, pp)n breakup reaction at 130 MeV deuteron beam energy has been measured in the domain of very forward polar angles with the use of the ...Germanium Wall detector at the Forschungszentrum Jülich. The data obtained for over 1000 kinematical points (112 geometries) are compared with the theoretical predictions based on various models of the three-nucleon (3N) dynamics. They comprise: the realistic nucleon-nucleon potentials alone or combined with the three-nucleon force (3NF), the coupled-channel calculations with the explicit treatment of the
Δ
-isobar excitation and finally, the potentials derived from chiral perturbation theory. In the part of the phase space studied, the Coulomb interaction between protons has a strong impact on the differential cross section of the breakup reaction. The strongest Coulomb effects are found in regions where the relative energy of the two protons is the smallest. In these regions the data are well reproduced exclusively by calculations which include the electromagnetic repulsion between protons. In spite of the dominance of the Coulomb force in the phase space studied, the contribution of 3NF effects is also observed.
Introduction The quality of cancer treatment with protons critically depends on the accurate determination of proton stopping powers (PSPs) of traversed tissues. Nowadays, proton treatment planning ...is based on stopping powers derived from X-ray Computed Tomography (CT) images leading to systematic uncertainties in the proton range in a patient of 3–4% and even up to 10% in regions containing bone. This may cause no dose in parts of the tumor and overdose in healthy tissues. Purpose In order to reduce the uncertainty in the translation of the X-ray CT image into a map of PSPs, we study proton radiography imaging as it delivers PSPs directly, without using a model. Materials and methods Using the Geant4 toolkit we simulate the proton radiography system with two position sensitive detectors and an energy detector. The imaged object is placed between the position detectors. The energy loss radiographs of the phantom with various, including tissue-like, materials are obtained. The multiple Coulomb scattering of a proton passing through various materials blurs the energy loss radiography image, but selecting protons travelling along almost straight paths decreases the blurring. Results Our simulations show that considering protons with small scattering angles increases sharpness between the material boundaries in the energy loss radiographs, and materials with small density differences are distinguished. Conclusion Proton radiography provides a direct information on PSPs of tissues inside the human body improving the accuracy of the calculation of the dose deposition by protons in a patient. Disclosure Authors have no relevant financial or nonfinancial relationships to disclose.
High-precision tensor analyzing power T
20
data of the
1
H (
d
,pp)n reaction at 130MeV beam energy have been determined for 81 kinematical configurations. They are compared to theoretical ...predictions based on various approaches to describe the dynamics of the three-nucleon (3N) system. The calculations are performed using modern realistic nucleon-nucleon potentials combined with three-nucleon force (3NF) models or with an effective 3NF resulting from the explicit treatment of the
-isobar in coupled-channels (CC) calculations. Alternatively, the framework of chiral perturbation theory is used to generate consistent two-nucleon and three-nucleon potentials at the currently numerically attainable order. Results of the CC calculations with the
degrees of freedom and including long-range Coulomb force are also shown. In general all predictions are consistent with each other and describe the experimental T
20
results quite well. In a few configurations small inconsistencies between the data and the results of all approaches are observed. Predicted effects of the 3NF are not big and in most cases do not lead to an improved description of the data. The Coulomb force effects are also small in size and often opposite to the effects of TM99 3NF.
PDF
