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Bussière, Marc R., i Judith A. Adams. "Treatment Planning for Conformal Proton Radiation Therapy". Technology in Cancer Research & Treatment 2, nr 5 (październik 2003): 389–99. http://dx.doi.org/10.1177/153303460300200504.
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Clinical results from various trials have demonstrated the viability of protons in radiation therapy and radiosurgery. This has motivated a few large medical centers to design and build expensive hospital based proton facilities based proton facilities (current cost estimates for a proton facility is around $100 million). Until this development proton therapy was done using retrofitted equipment originally designed for nuclear experiments. There are presently only three active proton therapy centers in the United States, 22 worldwide. However, more centers are under construction and being proposed in the US and abroad. The important difference between proton and x-ray therapy is in the dose distribution. X-rays deposit most of their dose at shallow depths of a few centimeters with a gradual decay with depth in the patient. Protons deliver most of their dose in the Bragg peak, which can be delivered at most clinically required depths followed by a sharp fall-off. This sharp falloff makes protons sensitive to variations in treatment depths within patients. Treatment planning incorporates all the knowledge of protons into a process, which allows patients to be treated accurately and reliably. This process includes patient immobilization, imaging, targeting, and modeling of planned dose distributions. Although the principles are similar to x-ray therapy some significant differences exist in the planning process, which described in this paper. Target dose conformality has recently taken on much momentum with the advent of intensity modulated radiation therapy (IMRT) with photon beams. Proton treatments provide a viable alternative to IMRT because they are inherently conformal avoiding normal tissue while irradiating the intended targets. Proton therapy will soon bring conformality to a new high with the development of intensity modulated proton therapy (IMPT). Future challenges include keeping the cost down, increasing access to conventional proton therapy as well as the clinical implementation of IMPT. Computing advances are making Monte Carlo techniques more accessible to treatment planning for all modalities including proton therapy. This technique will allow complex delivery configurations to be properly modeled in a clinical setting.
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Vanderwaeren, Laura, Rüveyda Dok, Kevin Verstrepen i Sandra Nuyts. "Clinical Progress in Proton Radiotherapy: Biological Unknowns". Cancers 13, nr 4 (3.02.2021): 604. http://dx.doi.org/10.3390/cancers13040604.
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Clinical use of proton radiation has massively increased over the past years. The main reason for this is the beneficial depth-dose distribution of protons that allows to reduce toxicity to normal tissues surrounding the tumor. Despite the experience in the clinical use of protons, the radiobiology after proton irradiation compared to photon irradiation remains to be completely elucidated. Proton radiation may lead to differential damages and activation of biological processes. Here, we will review the current knowledge of proton radiobiology in terms of induction of reactive oxygen species, hypoxia, DNA damage response, as well as cell death after proton irradiation and radioresistance.
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Graber, Jerome, Reed Ritterbusch i Lia Halasz. "NIMG-64. DISTINCT IMAGING PATTERNS OF PSEUDOPROGRESSION IN GLIOMA PATIENTS FOLLOWING PROTON VERSUS PHOTON RADIATION THERAPY". Neuro-Oncology 22, Supplement_2 (listopad 2020): ii162. http://dx.doi.org/10.1093/neuonc/noaa215.677.
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Abstract PURPOSE Radiologic Assessment in Neuro-Oncology (RANO) criteria define pseudoprogression (Ps) after photon radiation for gliomas, as occurring less than twelve weeks from radiation, within the high dose radiation field. However, some patients receiving proton manifest lesions that appear subjectively different from photon Ps based on timing and location (more than six months from radiation and deeper to the prior tumor), which would be called tumor progression by RANO. We retrospectively reviewed MRI changes after proton or photon radiation for gliomas. We propose criteria to characterize proton pseudoprogression (ProPs) distinct from photon pseudoprogression or tumor progression. METHODS Post-treatment MRIs of patients with gliomas were reviewed, along with clinical and pathological data. 77 proton patients were reviewed for the presence of ProPs, and 64 photon patients were reviewed for imaging changes. Data collected included the location, timing, and morphology of the lesions, tumor type, chemotherapy, and clinical symptoms. RESULTS 16 (21%) of the patients who received protons had imaging changes unique to protons, at a mean of 14.6 months after radiation. We established the following criteria to characterize ProPs: not immediately in or adjacent to the resection cavity; ~ 2cm opposite from target beam entry; can resolve without treatment; subjectively multifocal, patchy, small (< 1cm). None of the photon patients had lesions that met our criteria for ProPs (p< 0.001). CONCLUSION Patients who receive protons can have a unique subtype of pseudoprogression (Ps), which we refer to as proton pseudoprogression (or ProPs). These lesions could be mistaken for tumor progression, but typically resolve spontaneously. ProPs can possibly be explained by the increased relative biological effectiveness of protons and beam angle selection which may deposit at ~2cm deep to the target. Recognizing these lesions can prevent unnecessary treatment for mistaken tumor progression, especially in the context of clinical trials that include proton.
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Slater, Jerry D. "Clinical Applications of Proton Radiation Treatment at Loma Linda University: Review of a Fifteen-year Experience". Technology in Cancer Research & Treatment 5, nr 2 (kwiecień 2006): 81–89. http://dx.doi.org/10.1177/153303460600500202.
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Proton radiation therapy has been used at Loma Linda University Medical Center for 15 years, sometimes in combination with photon irradiation, surgery, and chemotherapy, but often as the sole modality. Our initial experience was based on established studies showing the utility of protons for certain management problems, but since then we have engaged in a planned program to exploit the capabilities of proton radiation and expand its applications in accordance with progressively accumulating clinical data. Our cumulative experience has confirmed that protons are a superb tool for delivering conformal radiation treatments, enabling delivery of effective doses of radiation and sparing normal tissues from radiation exposure.
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Beketov, Yevgeniy, Olga Lepilina, Vyacheslav Saburov, Aleksandr Chernukha, Liliya Ulyanenko, Olga Golovanova, Yegor Malakhov, Nadezhda Arguchinskaya, Yelena Isaeva i Stepan Ulyanenko. "BIOLOGICAL EFFICIENCY OF THE PROTON SCANNING BEAM OF THE THERAPEUTIC COMPLEX "PROMETHEUS" OF THE A.F. TSYB MEDICAL RADIOLOGICAL RESEARCH CENTER IN STUDIES ON CELL CULTURE OF MURINE MELANOMA B-16". Problems in oncology 64, nr 5 (1.05.2018): 678–82. http://dx.doi.org/10.37469/0507-3758-2018-64-5-678-682.
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The basis for the use of protons for radiation therapy tasks is a fixed conventional value of their relative biological efficiency equal to 1,1. Numerous studies have showed that RBE of proton radiation is not a constant value and depends on a number of factors. The purpose of this study was to determine RBE of a thin scanning proton beam at the center of the distributed Bragg peak in experiments on the culture of murine B-16 melanoma cells. The cell suspension was irradiated in an aqueous phantom by a horizontal proton beam from three directions (0,90 and 180°) in doses from 2 to 8 Gy. Modulation of the energy of proton radiation was 47,5÷92,0 MeV. RBE protons were determined from the clonogenic activity of the cells compared with 60Co gamma quanta. A linear-quadratic model was used to construct the dose dependencies. Obtained RBE values of proton radiation (LET 3÷8 keV/μm) differed in the big party from the generally accepted value and was at the level of 10% survival rate of 1.5. The results obtained generally coincided with data of foreign authors performed on different facilities.
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Pae, K. H., I. W. Choi i J. Lee. "Effect of target composition on proton acceleration by intense laser pulses in the radiation pressure acceleration regime". Laser and Particle Beams 29, nr 1 (5.01.2011): 11–16. http://dx.doi.org/10.1017/s0263034610000674.
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AbstractThe characteristics of high energy protons generated from thin carbon-proton mixture targets via circularly polarized intense laser pulses are investigated using two-dimensional particle-in-cell simulations. It is found that the density ratio n between protons and carbon ions plays a key role in determining the acceleration dynamics. For low n values, the protons are mainly accelerated by the radiation pressure acceleration mechanism, resulting in a quasi-monoenergetic energy spectrum. The radiation pressure acceleration mechanism is enhanced by the directed-Coulomb-explosion of carbon ions which gives a high proton maximum energy, though a large energy spread, for high n values. From a proton acceleration point of view, the role of heavy ions is very important. The fact that the proton energy spectrum is controllable based on the target composition is especially useful in real experimental environments.
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Rich, Tyvin, Dongfeng Pan, Mahendra Chordia, Cynthia Keppel, David Beylin, Pavel Stepanov, Mira Jung, Dalong Pang, Scott Grindrod i Anatoly Dritschilo. "18Oxygen Substituted Nucleosides Combined with Proton Beam Therapy: Therapeutic Transmutation In Vitro". International Journal of Particle Therapy 7, nr 4 (1.03.2021): 11–18. http://dx.doi.org/10.14338/ijpt-d-20-00036.1.
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Abstract Purpose Proton therapy precisely delivers radiation to cancers to cause damaging strand breaks to cellular DNA, kill malignant cells, and stop tumor growth. Therapeutic protons also generate short-lived activated nuclei of carbon, oxygen, and nitrogen atoms in patients as a result of atomic transmutations that are imaged by positron emission tomography (PET). We hypothesized that the transition of 18O to 18F in an 18O-substituted nucleoside irradiated with therapeutic protons may result in the potential for combined diagnosis and treatment for cancer with proton therapy. Materials and Methods Reported here is a feasibility study with a therapeutic proton beam used to irradiate H218O to a dose of 10 Gy produced by an 85 MeV pristine Bragg peak. PET imaging initiated >45 minutes later showed an 18F decay signal with T1/2 of ∼111 minutes. Results The 18O to 18F transmutation effect on cell survival was tested by exposing SQ20B squamous carcinoma cells to physiologic 18O-thymidine concentrations of 5 μM for 48 hours followed by 1- to 9-Gy graded doses of proton radiation given 24 hours later. Survival analyses show radiation sensitization with a dose modification factor (DMF) of 1.2. Conclusions These data support the idea of therapeutic transmutation in vitro as a biochemical consequence of proton activation of 18O to 18F in substituted thymidine enabling proton radiation enhancement in a cancer cell. 18O-substituted molecules that incorporate into cancer targets may hold promise for improving the therapeutic window of protons and can be evaluated further for postproton therapy PET imaging.
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Dzhuzha, Dmitry. "Charged particles therapy in radiation oncology". Radiation Diagnostics, Radiation Therapy, nr 1 (2020): 39–49. http://dx.doi.org/10.37336/2707-0700-2020-1-4.
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The physical and biological features of using protons and heavy ions in the treatment of malignant tumours were reviewed. It is showed that proton therapy is an effective method for treatment of malignant tumours, which has certain benefits comparing photon therapy. This modality may be recommended to 10-15 % of oncological patients. Carbon ion radiation therapy is especially perspective as it has local relative biological effectiveness till 2,0-3,5. The clinical efficacy of charged particles therapy at most expansive tumours was revealed. The cost efficacy of this type of radiation therapy was given. Key words: proton therapy, ion therapy, charged particles therapy, clinical efficacy of charged particles therapy.
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Romero, Gustavo E. "The non-thermal broadband spectral energy distribution of radio galaxies". Proceedings of the International Astronomical Union 7, S284 (wrzesień 2011): 407–10. http://dx.doi.org/10.1017/s1743921312009520.
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AbstractI present a model for the non-thermal production of electromagnetic radiation in the jets of radio galaxies. The model goes far beyond the simple one-zone models usually applied to these sources. The transport equation is solved in the co-moving frame of the jet, taken into account the inhomogeneous structure of the outflow. Energy distributions for all types of particles are then obtained in a self-consistent way, including protons, electrons, and secondaries. The spectral energy distribution resulting from all relevant radiative processes is computed, including synchrotron radiation, relativistic Bremsstrahlung, proton-proton collisions and subsequent decays, photo-meson production, radiation from pairs formed by photon absorption and injection from decays, as well as direct pair production. Absorbing fields in the host galaxy are considered when computing the final SED. The model is applied to Centaurus A and compared with the available multi-wavelength data.
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Solodky, V. A., T. R. Izmailov i P. V. Polushkin. "COMPARISON OF THE EFFECTIVENESS OF PROTON AND PHOTON THERAPY IN PATIENTS WITH BRAIN TUMORS". Siberian journal of oncology 20, nr 2 (2.05.2021): 127–35. http://dx.doi.org/10.21294/1814-4861-2021-20-2-127-135.
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Owing to the development of molecular genetics, the role of radiation therapy and chemotherapy in treatment of patients with glioma (WHO Grade I–IV) has become more understandable. The overall survival among glioma patients has increased. As overall survival increases, oncologists are more likely to detect manifestations of late radiation toxicity that has a huge impact on Quality of Life in patients who have undergone radiation therapy in the past. In this regard, the question of finding more adequate radiation therapy techniques remains relevant. photon radiation therapy is the standard method; however, considering dosimetric advantages of proton therapy over photon therapy, its widespread use can potentially lead to the increased overall survival, decreased number of late radiation-induced complications and improved quality of life in the post-radiation period. This article presents some comparative characteristics of proton and photon radiation therapy in patients with gliomas (WHO Grade I–IV). dosimetry characteristics of protons in tissues were compared, data showing differences in survival of patients treated with photons versus patients treated with protons were presented, and general information on early and late radiation-induced toxicity arising from the treatment by these methods was disclosed.
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YEVSEYEV, V. "RADIATION EFFECTS ON OPTICAL CHARACTERISTICS OF PbWO4". International Journal of Modern Physics B 22, nr 21 (20.08.2008): 3695–707. http://dx.doi.org/10.1142/s0217979208048541.
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The results of a study on the effect of γ- Co 60, fast (1 MeV) reactor neutron and 1 GeV proton irradiation on optical properties of lead tungstate ( PbWO 4) are presented. The peculiarities of optical absorption in PbWO 4 under these three types of irradiation are revealed. It is shown that in the case of irradiation of PbWO 4 with high energy particles 1 GeV protons, an essential role is played by large-scale radiation defects — disordered regions — and, related to it, fluctuating electrostatic potential. It is established that the efficiency of defect formation increases at the transition from gamma to neutron and further to proton irradiation.
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Choi, Changhoon, Chansu Lee, Sung-Won Shin, Shin-Yeong Kim, Sung Noh Hong i Hee Chul Park. "Comparison of Proton and Photon Beam Irradiation in Radiation-Induced Intestinal Injury Using a Mouse Model". International Journal of Molecular Sciences 20, nr 8 (17.04.2019): 1894. http://dx.doi.org/10.3390/ijms20081894.
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When radiotherapy is applied to the abdomen or pelvis, normal tissue toxicity in the gastrointestinal (GI) tract is considered a major dose-limiting factor. Proton beam therapy has a specific advantage in terms of reduced doses to normal tissues. This study investigated the fundamental differences between proton- and X-ray-induced intestinal injuries in mouse models. C57BL/6J mice were irradiated with 6-MV X-rays or 230-MeV protons and were sacrificed after 84 h. The number of surviving crypts per circumference of the jejunum was identified using Hematoxylin and Eosin staining. Diverse intestinal stem cell (ISC) populations and apoptotic cells were analyzed using immunohistochemistry (IHC) and a terminal deoxynucleotidyl transferase-mediated dUTP nick-end labelling (TUNEL) assay, respectively. The crypt microcolony assay revealed a radiation-dose-dependent decrease in the number of regenerative crypts in the mouse jejunum; proton irradiation was more effective than X-ray irradiation with a relative biological effectiveness of 1.14. The jejunum is the most sensitive to radiations, followed by the ileum and the colon. Both types of radiation therapy decreased the number of radiosensitive, active cycling ISC populations. However, a higher number of radioresistant, reserve ISC populations and Paneth cells were eradicated by proton irradiation than X-ray irradiation, as shown in the IHC analyses. The TUNEL assay revealed that proton irradiation was more effective in enhancing apoptotic cell death than X-ray irradiation. This study conducted a detailed analysis on the effects of proton irradiation versus X-ray irradiation on intestinal crypt regeneration in mouse models. Our findings revealed that proton irradiation has a direct effect on ISC populations, which may result in an increase in the risk of GI toxicity during proton beam therapy.
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Schulz-Ertner, Daniela, i Hirohiko Tsujii. "Particle Radiation Therapy Using Proton and Heavier Ion Beams". Journal of Clinical Oncology 25, nr 8 (10.03.2007): 953–64. http://dx.doi.org/10.1200/jco.2006.09.7816.
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Particle beams like protons and heavier ions offer improved dose distributions compared with photon (also called x-ray) beams and thus enable dose escalation within the tumor while sparing normal tissues. Although protons have a biologic effectiveness comparable to photons, ions, because they are heavier than protons, provide a higher biologic effectiveness. Recent technologic developments in the fields of accelerator engineering, treatment planning, beam delivery, and tumor visualization have stimulated the process of transferring particle radiation therapy (RT) from physics laboratories to the clinic. This review describes the physical, biologic, and technologic aspects of particle beam therapy. Clinical trials investigating proton and carbon ion RT will be summarized and discussed in the context of their relevance to recent concepts of treatment with RT.
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Wickstrand, Cecilia, Przemyslaw Nogly, Eriko Nango, So Iwata, Jörg Standfuss i Richard Neutze. "Bacteriorhodopsin: Structural Insights Revealed Using X-Ray Lasers and Synchrotron Radiation". Annual Review of Biochemistry 88, nr 1 (20.06.2019): 59–83. http://dx.doi.org/10.1146/annurev-biochem-013118-111327.
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Directional transport of protons across an energy transducing membrane—proton pumping—is ubiquitous in biology. Bacteriorhodopsin (bR) is a light-driven proton pump that is activated by a buried all- trans retinal chromophore being photoisomerized to a 13- cis conformation. The mechanism by which photoisomerization initiates directional proton transport against a proton concentration gradient has been studied by a myriad of biochemical, biophysical, and structural techniques. X-ray free electron lasers (XFELs) have created new opportunities to probe the structural dynamics of bR at room temperature on timescales from femtoseconds to milliseconds using time-resolved serial femtosecond crystallography (TR-SFX). Wereview these recent developments and highlight where XFEL studies reveal new details concerning the structural mechanism of retinal photoisomerization and proton pumping. We also discuss the extent to which these insights were anticipated by earlier intermediate trapping studies using synchrotron radiation. TR-SFX will open up the field for dynamical studies of other proteins that are not naturally light-sensitive.
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MacDonald, Shannon M., Thomas F. DeLaney i Jay S. Loeffler. "Proton Beam Radiation Therapy". Cancer Investigation 24, nr 2 (styczeń 2006): 199–208. http://dx.doi.org/10.1080/07357900500524751.
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Willison, John R. "Sonoluminescence: Proton-Tunneling Radiation". Physical Review Letters 81, nr 24 (14.12.1998): 5430–33. http://dx.doi.org/10.1103/physrevlett.81.5430.
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Paganetti, Harald. "Advancing (Proton) Radiation Therapy". International Journal of Radiation Oncology*Biology*Physics 87, nr 5 (grudzień 2013): 871–73. http://dx.doi.org/10.1016/j.ijrobp.2013.08.030.
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DeLaney, Thomas F. "Clinical Proton Radiation Therapy Research at the Francis H. Burr Proton Therapy Center". Technology in Cancer Research & Treatment 6, nr 4_suppl (sierpień 2007): 61–66. http://dx.doi.org/10.1177/15330346070060s410.
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The Francis H. Burr Proton Therapy Center has a 230 MeV cyclotron from which proton beams are directed to two isocentric gantries, a stereotactic intracranial beam line, and an eye line. Because of improved physical dose distribution, proton radiotherapy allows dose escalation to improve local tumor control in anatomic sites and histologies where local control is suboptimal with photons. The improved dose localization also reduces normal-tissue doses with an anticipated reduction in acute and late toxicity. Clinical treatment protocols, developed to exploit the dosimetric advantages of protons over photons, have been grouped into two broad categories. In the first, dose is escalated for anatomic sites where local control with conventional radiation doses has been suboptimal. In the second, normal-tissue sparing with protons is designed to minimize acute and late toxicity. Treatment of patients on clinical research protocols has been encouraged. Patient treatments began on the first gantry in November 2001; on the eye line in April 2002; on the second gantry in May 2002; and on the stereotactic intracranial line in August 2006. The facility currently treats 60 patients per day, including up to six children daily under anesthesia. Dose-escalation studies have been completed for early stage prostate cancer (in conjunction with Loma Linda University) and sarcomas of the cervical spine/base of skull and thoracolumbosacral spine. Protocols are in progress or development for carcinoma of the nasopharynx, paranasal sinus carcinoma, non-small-cell lung carcinoma, locally advanced carcinoma of the prostate, hepatocellular carcinoma, and pancreatic cancer. Studies evaluating the use of protons for morbidity reduction include protocols for craniospinal irradiation in conjunction with systemic chemotherapy for medulloblastoma, retinoblastoma, pediatric rhabdomyosarcoma, other pediatric sarcomas, and accelerated, hypofractionated partial breast irradiation for T1N0 breast carcinomas. For pediatric patients, protons have also been accepted as an alternative to photons for children enrolled in Children's Oncology Group (COG) protocols. Treatment of patients on these studies has often required the development of new treatment techniques ( i.e., matching abutting fields for craniospinal irradiation), respiratory gating, and development of appropriate clinical infrastructure support ( i.e., increase in availability of pediatric anesthesia) to allow appropriate treatment. In addition, a clinical research infrastructure for protocol development and data management is required. Results to date indicate that proton radiation therapy offers several potential treatment advantages to patients that can be studied in the setting of clinical trials. Patients' willingness to enter these clinical trials seems to be quite high; accrual to selected studies has been favorable.
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Chen, Clark C., Paul Chapman, Joshua Petit i Jay Loeffler. "Proton radiosurgery in neurosurgery". Neurosurgical Focus 23, nr 6 (grudzień 2007): E4. http://dx.doi.org/10.3171/foc-07/12/e5.
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Object Photon energy deposition from gamma or photon sources follows the law of exponential decay. Consequently, energy is deposited over the entire path of the radiation beam, resulting in dose distribution before and after the target is reached. In contrast, the physical properties of protons are such that energy deposition occurs with no exit dose beyond the target volume. Therefore, relative to photons, proton beams represent a superior platform for the administration of radiosurgery. Methods In this review, the authors will discuss the fundamental principles underlying photon- and proton-based stereotactic radiosurgery (SRS). The clinical efficacy of proton-based SRS in the treatment of arteriovenous malformations, vestibular schwannomas, and pituitary adenomas is reviewed. Results Direct comparisons of clinical results attained using photon- and proton-based SRS are confounded by a bias toward reserving proton beams for the treatment of larger and more complex lesions. Despite this bias, the clinical outcomes for proton-based SRS have been excellent and have been at least comparable to those for photon-based treatments. Conclusions The physical properties of proton radiation offer superior conformality in dose distribution relative to photon irradiation. This advantage becomes more apparent as the lesion size increases and will probably be magnified with the development of intensity-modulated proton techniques.
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Florentin, Matthieu, Mihaela Alexandru, Aurore Constant, Bernd Schmidt, José Millan i Philippe Godignon. "Low Energy Proton Radiation Impact on 4H-SiC nMOSFET Gate Oxide Stability". Materials Science Forum 778-780 (luty 2014): 525–28. http://dx.doi.org/10.4028/www.scientific.net/msf.778-780.525.
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The 4H-SiC MOSFET electrical response to 180 keV proton radiations at three different fluences has been evaluated. For a certain dose, the devices show an apparent improvement of their electrical characteristics likely due to the N and/or H atoms diffusion inside the oxide layer. This work complete our previous studies on high energy proton irradiation, showing that the 4H-SiC MOSFET is also robust to the low energy proton radiation, when the proton implanted range is located near the MOS interface.
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Katsoulakis, Evangelia, Natalya Chernichenko i David Schreiber. "Proton Therapy in the Treatment of Head and Neck Cancer". International Journal of Head and Neck Surgery 8, nr 2 (2017): 45–48. http://dx.doi.org/10.5005/jp-journals-10001-1305.
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ABSTRACT Aim To examine the value of proton therapy in relation to other treatment modalities in head and neck cancer. Review Proton therapy has evolved into more sophisticated and costly intensity-modulated proton therapy and has resulted in even greater dose reduction to normal critical structures at risk as compared with photon therapy. Early clinical studies in head and neck cancers, especially for tumors of the skull base and paranasal sinuses, suggest that proton therapy is excellent in terms of local control and is comparable to intensity-modulated radiation therapy photons but with lower rates of morbidity. Results There are many potential advantages to radiation therapy with protons. While there are many single institution studies examining the added value of protons to photon therapy, the value of proton therapy must be examined in prospective randomized clinical studies and across many subsites of head and neck cancer. Additional evidence is necessary to guide efficient clinical practice, patient selection, and tumors that are most likely to benefit from this treatment modality and justify proton therapy use given its significant cost. How to cite this article Katsoulakis E, Chernichenko N, Schreiber D. Proton Therapy in the Treatment of Head and Neck Cancer. Int J Head Neck Surg 2017;8(2):45-48.
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Woodward, Wendy A., i Richard A. Amos. "Proton Radiation Biology Considerations for Radiation Oncologists". International Journal of Radiation Oncology*Biology*Physics 95, nr 1 (maj 2016): 59–61. http://dx.doi.org/10.1016/j.ijrobp.2015.10.022.
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Thomas, Heike, i Beate Timmermann. "Paediatric proton therapy". British Journal of Radiology 93, nr 1107 (marzec 2020): 20190601. http://dx.doi.org/10.1259/bjr.20190601.
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Proton beam therapy is a highly conformal form of radiation therapy, which currently represents an important therapeutic component in multidisciplinary management in paediatric oncology. The precise adjustability of protons results in a reduction of radiation-related long-term side-effects and secondary malignancy induction, which is of particular importance for the quality of life. Proton irradiation has been shown to offer significant advantages over conventional photon-based radiotherapy, although the biological effectiveness of both irradiation modalities is comparable. This review evaluates current data from clinical and dosimetric studies on the treatment of tumours of the central nervous system, soft tissue and bone sarcomas of the head and neck region, paraspinal or pelvic region, and retinoblastoma. To date, the clinical results of irradiating childhood tumours with high-precision proton therapy are promising both with regard to tumour cure and the reduction of adverse events. Modern proton therapy techniques such as pencil beam scanning and intensity modulation are increasingly established modern facilities. However, further investigations with larger patient cohorts and longer follow-up periods are required, in order to be able to have clear evidence on clinical benefits.
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Hazdra, Pavel, i Stanislav Popelka. "Lifetime Control in SiC PiN Diodes Using Radiation Defects". Materials Science Forum 897 (maj 2017): 463–66. http://dx.doi.org/10.4028/www.scientific.net/msf.897.463.
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Application of radiation defects for lifetime control in contemporary SiC PiN diodes was investigated using the calibrated device simulator ATLAS from Silvaco, Inc. Recombination models accounting for the effect of deep levels introduced by the irradiation were set according to experimental results obtained by C-V and DLTS measurements performed on low-doped n-type SiC epilayers irradiated with 4.5 MeV electrons and 670 keV protons. Global (4.5 MeV electron irradiation) and local (700 keV proton irradiation) lifetime reduction was then applied on the 2A/10kV SiC PiN diode and the ON-state and reverse recovery characteristics were simulated and compared. Results show that the proton irradiation can substantially improve the trade‑off between the diode ON‑state and turn‑OFF losses. Compared to the electron irradiation, the local lifetime killing by protons allows achieving better trade-off and softer recovery curves.
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Olusoji, Olugbenga J., Crystal Penner, Camille Bélanger-Champagne, Wern Kam, Michael Martyn, Peter Woulfe, Cornelia Hoehr i Sinead O’Keeffe. "Dosimetric Application of Phosphorus Doped Fibre for X-ray and Proton Therapy". Sensors 21, nr 15 (30.07.2021): 5157. http://dx.doi.org/10.3390/s21155157.
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Phosphorous-doped silica optical fibres with a core diameter of 4 µm were tested in X-ray and proton fields for application in cancer therapy dosimetry. Specifically, the radiation-induced attenuation was investigated in terms of linearity in deposited dose in 15 MV and 6 MV photons and 74 MeV protons, as well as Bragg-peak detection along the proton track. Fibres were found to demonstrate linear relative dose response in both radiation modalities, but possible saturation did occur at the high linear energy transfer of the Bragg peak. This demonstrates the possibility to use these fibres as a relative dosimeter for radiation therapy applications.
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Mastichiadis, Apostolos, Ioulia Florou, Elina Kefala, Stella S. Boula i Maria Petropoulou. "A roadmap to hadronic supercriticalities: a comprehensive study of the parameter space for high-energy astrophysical sources". Monthly Notices of the Royal Astronomical Society 495, nr 2 (11.05.2020): 2458–74. http://dx.doi.org/10.1093/mnras/staa1308.
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ABSTRACT Hadronic supercriticalities are radiative instabilities that appear when large amounts of energy are stored in relativistic protons. When the proton energy density exceeds some critical value, a runaway process is initiated resulting in the explosive transfer of the proton energy into electron–positron pairs and radiation. The runaway also leads to an increase of the radiative efficiency, namely the ratio of the photon luminosity to the injected proton luminosity. We perform a comprehensive study of the parameter space by investigating the onset of hadronic supercriticalities for a wide range of source parameters (i.e. magnetic field strengths of 1 G−100 kG and radii of 1011−1016 cm) and maximum proton Lorentz factors (103−109). We show that supercriticalities are possible for the whole range of source parameters related to compact astrophysical sources, like gamma-ray bursts and cores and jets of active galactic nuclei. We also provide an in-depth look at the physical mechanisms of hadronic supercriticalities and show that magnetized relativistic plasmas are excellent examples of non-linear dynamical systems in high-energy astrophysics.
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Funtikov, Yurii V., Leonid Yu Dubov, Yurii V. Shtotsky i Sergey V. Stepanov. "Radiation-Induced Defects in Si after High Dose Proton Irradiation". Defect and Diffusion Forum 373 (marzec 2017): 209–12. http://dx.doi.org/10.4028/www.scientific.net/ddf.373.209.
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Experiments on investigation of the radiation defects produced as a result of high energy proton irradiation of single crystal Si wafers are carried out. Parameters of the proton irradiation facility are presented. It is shown that the most efficient radiation defect formation correlates with the position of the Bragg peak of ionization losses. LT spectra were measured just after irradiation and then after keeping Si samples during 3 months of at room T. We did not observe any variation of the number density of the defects, except for the 7th wafer, where most part of protons was stopped. An efficient annealing of the vacancy-type defects starts at temperatures slightly lower than 100 °C (during 10 min). Annealing at about 700 °C leads to recovering of the monoexponrntial shape of the LT spectra.
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Sikora, Marek, Bronisław Rudak i Mitchell Begelman. "Relativistic Neutrons in Active Galactic Nuclei". Symposium - International Astronomical Union 134 (1989): 215–16. http://dx.doi.org/10.1017/s0074180900140902.
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A substantial fraction of the radiation from an active galactic nucleus (AGN) is apparently nonthermal in origin, and is probably produced by ultrarelativistic electrons. How much energy goes into relativistic protons is uncertain, but it is likely to be comparable to the electron energy or larger. Indeed, several authors (Sikora et al. 1987; Kazanas and Ellison 1986; Zdziarski 1986) have shown that proton-photon and proton-proton collisions can be efficient sources of relativistic pairs in the central engine of an AGN. Thus it is not necessary for electrons to be accelerated directly in AGNs, provided that protons are accelerated with high enough efficiency.
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Zhu, Bin, Yi Sheng Zhang, Jian Gong Hu, Hong Guang Yang i Qin Zhan. "Simulation of Radiation Damage for the Typical Tritium Permeation Barrier Coating Materials". Advanced Materials Research 308-310 (sierpień 2011): 1226–29. http://dx.doi.org/10.4028/www.scientific.net/amr.308-310.1226.
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The study of tritium permeation barrier (TPB) coating is one of the most important subjects in the development of liquid lithium blankets in International Thermonuclear Experiment Reactor (ITER). Radiation-shielding property is one of the most important assessment indicators of TPB coating materials. Radiation damage experiment is difficult to perform, so with the Monte Carlo code TRIM(Transport of Ions in Matter), simulations of proton irradiation have been done for three kinds of candidate materials-Al2O3, Er2O3, Y2O3.This study focuses on the energy transfer, energy loss, and vacancies of the protons, as well as the stopping power of coating materials. According to the calculation results, Al2O3 has the strongest resistance against tritium permeation while more vacancies are produced after proton radiation.
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Slater, Jerry D. "Development and Operation of the Loma Linda University Medical Center Proton Facility". Technology in Cancer Research & Treatment 6, nr 4_suppl (sierpień 2007): 67–72. http://dx.doi.org/10.1177/15330346070060s411.
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The Proton Treatment Center at Loma Linda University Medical Center, the world's first hospital-based proton facility, opened in 1990 after two decades of development. Its early years were marked by a deliberately cautious approach in clinical utilization of protons, with intent to establish hospital-based proton therapy on a scientific basis. The facility was designed to be upgradeable, and development since 1990 has proceeded in three distinct phases of upgrades, both in technology and clinical applications. Upgrades continue, all of them based on an underlying program of basic and clinical research; future new applications of proton radiation therapy are expected to follow.
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Bavle, Abhishek, Michael Confer, Hilarie Simpson, Theresa Gavula, Naina Gross, Maria Lim, Rene McNall-Knapp i Janine Collinge. "NCOG-64. INCIDENCE OF EARLY OCULAR COMPLICATIONS AFTER PROTON RADIATION FOR CHILDHOOD BRAIN TUMORS". Neuro-Oncology 22, Supplement_2 (listopad 2020): ii143—ii144. http://dx.doi.org/10.1093/neuonc/noaa215.602.
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Abstract OBJECTIVES To determine the incidence, timing and risk factors of ocular complications after proton radiation (RT) in childhood brain tumor patients, to better inform screening for these complications. METHODS We performed a single-institution retrospective review of children treated with proton RT for brain tumors, with ophthalmology data available. Data abstracted included demographics, radiation details and ocular complications (cataract, dry eyes, retinal changes). RESULTS We treated 81 children with brain tumors, with protons, from 2010-18. Forty three patients with ophthalmology data available, were included in the study, with a median age of 8.3 years (y) (0.8 – 20.6y) (13 craniospinal irradiation/CSI, 27 involved-field radiation/IFRT, 3 whole ventricle). Median follow-up from end of radiation to last eye exam was 2.1y (0.2 – 7.2y). The incidence of ocular complications was 21% (9/43 patients) overall, and 62% (8/13) after CSI. Bilateral cataracts were detected at a median of 3.2y post-radiation, with incidence of 14% (6/43) overall and 38% (5/13) after CSI. Three patients underwent lens replacement. Dry eyes developed in 23% (3/13) of patients during or soon after CSI (0.04 and 0.7y post-RT). One patient with craniopharyngioma developed retinal scarring and cataracts, 2.2y and 3.5y, after IFRT. The median radiation dose to the lenses, for patients with cataract, was 26.02 Gy RBE (4 patients: 19.41 – 31.54). For 3 patients with dry eyes, the median dose (Gy RBE) was 27.93 (11.98 – 28.71) to lenses, 36.96 (25.12 – 47.49) to lacrimal glands and 30.78 (25.08 – 36.49) to corneas (mean doses to bilateral ocular structures). CONCLUSIONS Children are at risk for cataract and dry eyes after cranial protons, especially CSI, and need ophthalmology follow-up. Larger studies are needed to validate these findings and identify risk-mitigation strategies, with longer follow-up to determine the incidence of ocular complications, and functional outcomes, after cranial proton radiation.
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Luitel, Krishna, Ronald Bozeman, Aadil Kaisani, Sang Bum Kim, Summer Barron, James A. Richardson i Jerry W. Shay. "Proton radiation-induced cancer progression". Life Sciences in Space Research 19 (listopad 2018): 31–42. http://dx.doi.org/10.1016/j.lssr.2018.08.002.
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Schreuder, Niek. "Proton Therapy. Radiation Medicine Rounds". Medical Physics 38, nr 10 (28.09.2011): 5831–32. http://dx.doi.org/10.1118/1.3639118.
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Suit, H., i M. Urie. "Proton Beams in Radiation Therapy". JNCI Journal of the National Cancer Institute 84, nr 3 (5.02.1992): 155–64. http://dx.doi.org/10.1093/jnci/84.3.155.
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Klein, E. E., C. Block, B. Pierburg i J. Bradley. "Single Room Proton Radiation Therapy". International Journal of Radiation Oncology*Biology*Physics 84, nr 3 (listopad 2012): S835—S836. http://dx.doi.org/10.1016/j.ijrobp.2012.07.2237.
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Kovtyukh, Alexander S. "Distribution of Earth's radiation belts' protons over the drift frequency of particles". Annales Geophysicae 39, nr 1 (23.02.2021): 171–79. http://dx.doi.org/10.5194/angeo-39-171-2021.
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Abstract. Using data on the proton fluxes of the Earth's radiation belts (ERBs) with energy ranging from 0.2 to 100 MeV on the drift L shells ranging from 1 to 8, the quasi-stationary distributions over the drift frequency fd of protons around the Earth are constructed. For this purpose, direct measurements of proton fluxes of the ERBs during the period from 1961 to 2017 near the geomagnetic equator were employed. The main physical processes in the ERB manifested more clearly in these distributions, and for protons with fd>0.5 mHz at L>3, their distributions in the {fd,L} space have a more regular shape than in the {E,L} space. It has also been found that the quantity of the ERB protons with fd ∼ 1–10 mHz at L∼2 does not decrease, as it does for protons with E > 10–20 MeV (with fd>10 mHz), but increases with an increase in solar activity. This means that the balance of radial transport and loss of ERB low-energy protons at L∼2 is disrupted in favor of transport of these protons: the effect of an increase in the radial diffusion rates with increasing solar activity overpowers the effect of an increase in the density of the dissipative medium.
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Sicard, Angélica, Daniel Boscher, Sébastien Bourdarie, Didier Lazaro, Denis Standarovski i Robert Ecoffet. "GREEN: the new Global Radiation Earth ENvironment model (beta version)". Annales Geophysicae 36, nr 4 (4.07.2018): 953–67. http://dx.doi.org/10.5194/angeo-36-953-2018.
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Abstract. GREEN (Global Radiation Earth ENvironment) is a new model (in beta version) providing fluxes at any location between L∗= 1 and L∗= 8, all along the magnetic field lines, for all local times and for any energy between 1 keV and 10 MeV for electrons and between 1 keV and 800 MeV for protons. This model is composed of global models (AE8 and AP8, and SPM for low energies) and local models (SLOT model, OZONE and IGE-2006 for electrons, and OPAL and IGP for protons). GREEN is not just a collection of various models; it calculates the electron and proton fluxes from the most relevant existing model for a given energy and location. Moreover, some existing models can be updated or corrected in GREEN. For examples, a new version of the SLOT model is presented here and has been integrated in GREEN. Moreover, a new model of proton flux in geostationary orbit (IGP) developed a few years ago is also detailed here and integrated in GREEN. Finally a correction of the AE8 model at high energy for L∗ < 2.5 has also been implemented. The inputs of the GREEN model are the coordinates of the points and the date (year, month, day, UTC) along an orbit, the particle species (electron or proton) and the energies. Then GREEN provides fluxes all along the given orbit, depending on the solar cycle and other magnetic parameters such as L∗, Bmirror and Beq.
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Austin-Seymour, Mary, John Munzenrider, Michael Goitein, Lynn Verhey, Marcia Urie, Richard Gentry, Steven Birnbaum i in. "Fractionated proton radiation therapy of chordoma and low-grade chondrosarcoma of the base of the skull". Journal of Neurosurgery 70, nr 1 (styczeń 1989): 13–17. http://dx.doi.org/10.3171/jns.1989.70.1.0013.
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✓ Sixty-eight patients with chordoma or low-grade chondrosarcoma at the base of the skull received fractionated high-dose postoperative radiation delivered with a 160-MeV proton beam. Protons have favorable physical characteristics which allow the delivery of high doses of radiation to these critically located tumors. The methods employed for these treatments are described. These patients have been followed for at least 17 months and for a median of 34 months. The median tumor dose was 69 CGE (cobalt Gy equivalent): CGE is the dose in proton Gy multiplied by 1.1, which is the relative biological effectiveness for protons compared to cobalt-60. The daily dose was 1.8 to 2.1 CGE. For this group the 5-year actuarial local control rate is 82% and disease-free survival rate is 76%. The incidence of treatment-related morbidity has been acceptable.
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Lee, Harold O., Muhammed Hasib i Sam-Shajing Sun. "Proton Radiation Studies on Conjugated Polymer Thin Films". MRS Advances 2, nr 51 (2017): 2967–72. http://dx.doi.org/10.1557/adv.2017.389.
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ABSTRACTPolymeric thin film based electronic and optoelectronic materials and devices are attractive for potential space and certain radiation related applications due to their inherent features such as being light weight, flexible, biocompatible and environmental friendly, etc. Proton radiation is a major form of ionizing radiation in space, yet very few literature and data are available on proton radiation effects on conjugated polymer systems. In this study, UV-Vis absorption spectra of several conjugated polymers and/or their composite thin films were measured and compared right before and after a 200 MeV proton beam irradiation at different dosages, and the results revealed that proton radiation has very little or negligible impact up to 800 Rads on the optoelectronic properties of several polymers and their composite thin films.
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Coutrakon, George B. "Accelerators for Heavy-charged-particle Radiation Therapy". Technology in Cancer Research & Treatment 6, nr 4_suppl (sierpień 2007): 49–54. http://dx.doi.org/10.1177/15330346070060s408.
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This paper focuses on current and future designs of medical hadron accelerators for treating cancers and other diseases. Presently, five vendors and several national laboratories have produced heavy-particle medical accelerators for accelerating nuclei from hydrogen (protons) up through carbon and oxygen. Particle energies are varied to control the beam penetration depth in the patient. As of the end of 2006, four hospitals and one clinic in the United States offer proton treatments; there are five more such facilities in Japan. In most cases, these facilities use accelerators designed explicitly for cancer treatments. The accelerator types are a combination of synchrotrons, cyclotrons, and linear accelerators; some carry advanced features such as respiration gating, intensity modulation, and rapid energy changes, which contribute to better dose conformity on the tumor when using heavy charged particles. Recent interest in carbon nuclei for cancer treatment has led some vendors to offer carbon-ion and proton capability in their accelerator systems, so that either ion can be used. These features are now being incorporated for medical accelerators in new facilities.
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Jin, Michael C., Siyu Shi, Adela Wu, Navjot Sandhu, Michael Xiang, Scott G. Soltys, Susan Hiniker, Gordon Li i Erqi L. Pollom. "Impact of proton radiotherapy on treatment timing in pediatric and adult patients with CNS tumors". Neuro-Oncology Practice 7, nr 6 (18.06.2020): 626–35. http://dx.doi.org/10.1093/nop/npaa034.
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Abstract Background Despite putative benefits associated with proton radiotherapy in the setting of CNS tumors, numerous barriers limit treatment accessibility. Given these challenges, we explored the association of proton use with variations in treatment timing. Methods Pediatric and adult patients with histologically confirmed CNS tumors were identified from the National Cancer Database (2004-2015). Univariable and multivariable regression models were constructed to assess factors impacting radiation timing. Multivariable Cox regression was used to evaluate the effect of treatment delay on survival. Results A total of 76 157 patients received photon or proton radiotherapy. Compared to photons, time to proton administration was longer in multiple pediatric (embryonal, ependymal, nonependymal glial, and other) and adult (ependymal, nonependymal glial, meningeal, other) tumor histologies. On adjusted analysis, proton radiotherapy was associated with longer delays in radiotherapy administration in pediatric embryonal tumors (+3.00 weeks, P = .024) and in all adult tumors (embryonal [+1.36 weeks, P = .018], ependymal [+3.15 weeks, P < .001], germ cell [+2.65 weeks, P = .024], glial [+2.15 weeks, P < .001], meningeal [+5.05 weeks, P < .001], and other [+3.06 weeks, P < .001]). In patients with high-risk tumors receiving protons, delays in adjuvant radiotherapy were independently associated with poorer survival (continuous [weeks], adjusted hazard ratio = 1.09, 95% CI = 1.02-1.16). Conclusions Proton radiotherapy is associated with later radiation initiation in pediatric and adult patients with CNS tumors. In patients with high-risk CNS malignancies receiving protons, delayed adjuvant radiotherapy is associated with poorer survival. Further studies are needed to understand this discrepancy to maximize the potential of proton radiotherapy for CNS malignancies.
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Bravatà, Valentina, Francesco P. Cammarata, Luigi Minafra, Pietro Pisciotta, Concetta Scazzone, Lorenzo Manti, Gaetano Savoca i in. "Proton-irradiated breast cells: molecular points of view". Journal of Radiation Research 60, nr 4 (28.05.2019): 451–65. http://dx.doi.org/10.1093/jrr/rrz032.
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Abstract Breast cancer (BC) is the most common cancer in women, highly heterogeneous at both the clinical and molecular level. Radiation therapy (RT) represents an efficient modality to treat localized tumor in BC care, although the choice of a unique treatment plan for all BC patients, including RT, may not be the best option. Technological advances in RT are evolving with the use of charged particle beams (i.e. protons) which, due to a more localized delivery of the radiation dose, reduce the dose administered to the heart compared with conventional RT. However, few data regarding proton-induced molecular changes are currently available. The aim of this study was to investigate and describe the production of immunological molecules and gene expression profiles induced by proton irradiation. We performed Luminex assay and cDNA microarray analyses to study the biological processes activated following irradiation with proton beams, both in the non-tumorigenic MCF10A cell line and in two tumorigenic BC cell lines, MCF7 and MDA-MB-231. The immunological signatures were dose dependent in MCF10A and MCF7 cell lines, whereas MDA-MB-231 cells show a strong pro-inflammatory profile regardless of the dose delivered. Clonogenic assay revealed different surviving fractions according to the breast cell lines analyzed. We found the involvement of genes related to cell response to proton irradiation and reported specific cell line- and dose-dependent gene signatures, able to drive cell fate after radiation exposure. Our data could represent a useful tool to better understand the molecular mechanisms elicited by proton irradiation and to predict treatment outcome
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Hazdra, Pavel, Rupendra Kumar Sharma i Stanislav Popelka. "The Effect of Proton and Carbon Irradiation on 4H-SiC 1700V MPS Diode Characteristics". Materials Science Forum 821-823 (czerwiec 2015): 612–15. http://dx.doi.org/10.4028/www.scientific.net/msf.821-823.612.
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Electronic properties of radiation damage produced in 1700 V 4H-SiC MPS diodes by proton and carbon irradiation were investigated and compared. 4H-SiC epilayers, which formed the lowdoped N-base of MPS power diodes, were irradiated to identical depth with 670 keV protons and 9.6 MeV C4+ ions. Results show that irradiation with both projectiles produces strongly localized damage (deep levels) peaking at ion’s projected range. Compared to protons, heavier carbon ions introduce more defects with deeper levels in the SiC bandgap and more stable damage. Radiation damage act as electron traps and compensates donor doping of the epilayer and decreases electron mobility. Forward voltage drop of irradiated diodes then sharply increases when the peak concentration of introduced acceptor levels donor doping. The effect of both the proton and carbon irradiation can be simulated using a simple model accounting only for one dominant electron trap.
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Görte, Josephine, Elke Beyreuther, Erik H. J. Danen i Nils Cordes. "Comparative Proton and Photon Irradiation Combined with Pharmacological Inhibitors in 3D Pancreatic Cancer Cultures". Cancers 12, nr 11 (31.10.2020): 3216. http://dx.doi.org/10.3390/cancers12113216.
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Pancreatic ductal adenocarcinoma (PDAC) is a highly therapy-resistant tumor entity of unmet needs. Over the last decades, radiotherapy has been considered as an additional treatment modality to surgery and chemotherapy. Owing to radiosensitive abdominal organs, high-precision proton beam radiotherapy has been regarded as superior to photon radiotherapy. To further elucidate the potential of combination therapies, we employed a more physiological 3D, matrix-based cell culture model to assess tumoroid formation capacity after photon and proton irradiation. Additionally, we investigated proton- and photon-irradiation-induced phosphoproteomic changes for identifying clinically exploitable targets. Here, we show that proton irradiation elicits a higher efficacy to reduce 3D PDAC tumoroid formation and a greater extent of phosphoproteome alterations compared with photon irradiation. The targeting of proteins identified in the phosphoproteome that were uniquely altered by protons or photons failed to cause radiation-type-specific radiosensitization. Targeting DNA repair proteins associated with non-homologous endjoining, however, revealed a strong radiosensitizing potential independent of the radiation type. In conclusion, our findings suggest proton irradiation to be potentially more effective in PDAC than photons without additional efficacy when combined with DNA repair inhibitors.
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Lee, Anna, Julie Kang, Yao Yu, Sean McBride, Nadeem Riaz, Marc Cohen, Eric Sherman, Loren Michel, Nancy Lee i C. Jillian Tsai. "Trends and Disparities of Proton Therapy Use among Patients with Head and Neck Cancer: Analysis from the National Cancer Database (2005-14)". International Journal of Particle Therapy 5, nr 4 (1.03.2019): 1–10. http://dx.doi.org/10.14338/ijpt-19-00051.1.
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Abstract Purpose: The purpose of this study was to analyze national trends and disparities in proton therapy use among patients with head and neck cancer receiving radiotherapy to primary disease sites. Patients and Methods: Using the National Cancer Database, we identified patients diagnosed with any nonmetastatic head and neck primary malignancy between 2005 and 2014 who were treated with radiation therapy or proton therapy directed specifically at the primary disease site. Distributions of patient and clinical factors between the two groups were evaluated. Multivariable logistic regression was used to correlate factors associated with proton therapy use compared with other modalities of radiation therapy. Results: There were 220 491 patients who received any radiation therapy as part of their initial treatment course, only 417 (0.2%) of whom received proton therapy. The use of protons underwent a small increase from 0.13% in 2005-06 to 0.41% by 2013-14 (P < .001). The most common primary sites treated with proton therapy were the nasal cavity/nasopharynx (n = 151, 36.2%) and the oral cavity (n = 98, 23.5%). Most patients had T4 disease (n = 94, 31.0%). On multivariable logistic regression, all primary sites compared with hypopharynx/larynx sites (odds ratio [OR], 2.53-10.53; P < .001), treatment at an academic facility (OR, 2.54; P < .001), ≥ 13-mile distance from the treating facility (OR, 1.94; P < .001), and highest median household income quartile (> $63 000; OR, 2.52; P = .002) were associated with an increased likelihood of receiving proton therapy. Conclusion: Proton use has undergone an incremental increase in the United States but remains an uncommon modality for the treatment of primary head and neck cancer.
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Beebe-Wang, Joanne, Avraham Dilmanian, Stephen Peggs, David Schlyer i Paul Vaska. "Pet imaging of dose distribution in proton-beam cancer therapy". Nuclear Technology and Radiation Protection 20, nr 1 (2005): 23–26. http://dx.doi.org/10.2298/ntrp0501023b.
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Proton therapy is a treatment modality of increasing utility in clinical radiation oncology mostly because its dose distribution conforms more tightly to the target volume than X-ray radiation therapy. One important feature of proton therapy is that it produces a small amount of positron-emitting isotopes along the beam-path through the non-elastic nuclear interaction of protons with target nuclei such as 12C, 14N, and 16O. These radio isotopes, mainly 11C, 13N, and 15O, al low imaging the therapy dose distribution using positron emission tomography. The resulting positron emission tomography images provide a powerful tool for quality assurance of the treatment, especially when treating inhomogeneous organs such as the lungs or the head-and-neck, where the calculation of the dose distribution for treatment planning is more difficult. This pa per uses Monte Carlo simulations to predict the yield of positron emitters produced by a 250 MeV proton beam, and to simulate the productions of the image in a clinical PET scanner.
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McNamara, Aimee, Henning Willers i Harald Paganetti. "Modelling variable proton relative biological effectiveness for treatment planning". British Journal of Radiology 93, nr 1107 (marzec 2020): 20190334. http://dx.doi.org/10.1259/bjr.20190334.
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Dose in proton radiotherapy is generally prescribed by scaling the physical proton dose by a constant value of 1.1. Relative biological effectiveness (RBE) is defined as the ratio of doses required by two radiation modalities to cause the same level of biological effect. The adoption of an RBE of 1.1. assumes that the biological efficacy of protons is similar to photons, allowing decades of clinical dose prescriptions from photon treatments and protocols to be utilized in proton therapy. There is, however, emerging experimental evidence that indicates that proton RBE varies based on technical, tissue and patient factors. The notion that a single scaling factor may be used to equate the effects of photons and protons across all biological endpoints and doses is too simplistic and raises concern for treatment planning decisions. Here, we review the models that have been developed to better predict RBE variations in tissue based on experimental data as well as using a mechanistic approach.
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Lu, D., E. Xanthopoulos, N. Dixit, P. James, N. Mitra, W. Levin, R. Rengan, S. M. Hahn, S. Both i C. B. Simone. "Comparison of Intensity Modulated Radiation Therapy, Adaptive Radiation Therapy, Proton Radiation Therapy, and Adaptive Proton Radiation Therapy for Small Cell Lung Cancer". International Journal of Radiation Oncology*Biology*Physics 87, nr 2 (październik 2013): S510. http://dx.doi.org/10.1016/j.ijrobp.2013.06.1349.
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Talman, Richard. "Scaling behavior of circular colliders dominated by synchrotron radiation". International Journal of Modern Physics A 30, nr 23 (19.08.2015): 1544003. http://dx.doi.org/10.1142/s0217751x15440030.
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The scaling formulas in this paper — many of which involve approximation — apply primarily to electron colliders like CEPC or FCC-ee. The more abstract “radiation dominated” phrase in the title is intended to encourage use of the formulas — though admittedly less precisely — to proton colliders like SPPC, for which synchrotron radiation begins to dominate the design in spite of the large proton mass. Optimizing a facility having an electron–positron Higgs factory, followed decades later by a p, p collider in the same tunnel, is a formidable task. The CEPC design study constitutes an initial “constrained parameter” collider design. Here the constrained parameters include tunnel circumference, cell lengths, phase advance per cell, etc. This approach is valuable, if the constrained parameters are self-consistent and close to optimal. Jumping directly to detailed design makes it possible to develop reliable, objective cost estimates on a rapid time scale. A scaling law formulation is intended to contribute to a “ground-up” stage in the design of future circular colliders. In this more abstract approach, scaling formulas can be used to investigate ways in which the design can be better optimized. Equally important, by solving the lattice matching equations in closed form, as contrasted with running computer programs such as MAD, one can obtain better intuition concerning the fundamental parametric dependencies. The ground-up approach is made especially appropriate by the seemingly impossible task of simultaneous optimization of tunnel circumference for both electrons and protons. The fact that both colliders will be radiation dominated actually simplifies the simultaneous optimization task. All GeV scale electron accelerators are “synchrotron radiation dominated”, meaning that all beam distributions evolve within a fraction of a second to an equilibrium state in which “heating” due to radiation fluctuations is canceled by the “cooling” in RF cavities that restore the lost energy. To the contrary, until now, the large proton to electron mass ratio has caused synchrotron radiation to be negligible in proton accelerators. The LHC beam energy has still been low enough that synchrotron radiation has little effect on beam dynamics; but the thermodynamic penalty in cooling the superconducting magnets has still made it essential for the radiated power not to be dissipated at liquid helium temperatures. Achieving this has been a significant challenge. For the next generation p, p collider this will be even more true. Furthermore, the radiation will effect beam distributions on time scales measured in minutes, for example causing the beams to be flattened, wider than they are high. In this regime scaling relations previously valid only for electrons will be applicable also to protons.
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Condruz, Mihaela Raluca, Cristian Puscasu, Lucia Raluca Voicu, Ionut Sebastian Vintila, Alexandru Paraschiv i Dragos Alexandru Mirea. "Fiber Reinforced Composite Materials for Proton Radiation Shielding". Materiale Plastice 55, nr 1 (30.03.2018): 5–8. http://dx.doi.org/10.37358/mp.18.1.4952.
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Nowadays scientific researchers aim to develop new material designs for space structures that can withstand the harsh conditions in space environment. Another goal is to reduce the weight and the launching cost of the structures. A solution to those needs is to integrate fiber reinforced polymers in spacecraft structural components. Radiation shielding is a requirement that has to be met by the materials used to manufacture space structures. Protons are one of the many charged particles that can influence the integrity of materials in space. In the present study three material designs were developed and their ability to shield proton beam irradiation was evaluated. The material designs consist in advanced composite materials (carbon fiber reinforced polymers - CFRPs) that integrate the concept Low Z - High Z - Low Z (tantalum foil) and metallic coatings. Simulations were performed to determine the penetration depth of an ion beam (energy 15 MeV) in the proposed material designs. It was observed that the beam�s penetration depth through a CFRP sample with Ta foil (sample�s thickness 2.08 mm) was about 75% of the sample�s thickness, 58% for CFRP sample with Babbitt coating (sample�s thickness 2.28 mm), 56% for the CFRP sample with Zn coating (sample�s thickness 2.28 mm) and 55% for the CFRP sample with Zn/Monel coating (sample�s thickness 2.28 mm). It seems that the proposed material designs provide ion beam protection similar with an aluminum sample of 2 mm thickness. The experimental procedure confirmed the results obtained from the simulations, all the material designs providing protection in case of proton beam irradiation with an energy of 15.8 MeV.