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Title: Dose contributions from large-angle scattered particles in therapeutic carbon beams

Abstract

In carbon therapy, doses at center of spread-out Bragg peaks depend on field size. For a small field of 5x5 cm{sup 2}, the central dose reduces to 96% of the central dose for the open field in case of 400 MeV/n carbon beam. Assuming the broad beam injected to the water phantom is made up of many pencil beams, the transverse dose distribution can be reconstructed by summing the dose distribution of the pencil beams. We estimated dose profiles of this pencil beam through measurements of dose distributions of broad uniform beams blocked half of the irradiation fields. The dose at a distance of a few cm from the edge of the irradiation field reaches up to a few percent of the central dose. From radiation quality measurements of this penumbra, the large-angle scattered particles were found to be secondary fragments which have lower LET than primary carbon beams. Carbon ions break up in beam modifying devices or in water phantom through nuclear interaction with target nuclei. The angular distributions of these fragmented nuclei are much broader than those of primary carbon particles. The transverse dose distribution of the pencil beam can be approximated by a function of the three-Gaussianmore » form. For a simplest case of mono-energetic beam, contributions of the Gaussian components which have large mean deviations become larger as the depth in the water phantom increases.« less

Authors:
; ; ; ; ; ; ;  [1];  [2];  [2];  [2];  [2]
  1. Tokai University Unified Graduate School, Graduate School of Science and Technology, 1117 Kitakaname, Hiratsuka, Kanagawa, 259-1292, Japan and Accelerator Engineering Co., 2-13-1 Konakadai, Inage-ku, Chiba 263-0043 (Japan)
  2. (Japan)
Publication Date:
OSTI Identifier:
20853909
Resource Type:
Journal Article
Resource Relation:
Journal Name: Medical Physics; Journal Volume: 34; Journal Issue: 1; Other Information: DOI: 10.1118/1.2402328; (c) 2007 American Association of Physicists in Medicine; Country of input: International Atomic Energy Agency (IAEA)
Country of Publication:
United States
Language:
English
Subject:
62 RADIOLOGY AND NUCLEAR MEDICINE; ANGULAR DISTRIBUTION; BEAMS; BRAGG CURVE; CARBON IONS; DOSIMETRY; GAUSS FUNCTION; IRRADIATION; LET; PHANTOMS; RADIATION DOSE DISTRIBUTIONS; RADIATION DOSES; RADIATION QUALITY; RADIOTHERAPY

Citation Formats

Kusano, Yohsuke, Kanai, Tatsuaki, Kase, Yuki, Matsufuji, Naruhiro, Komori, Masataka, Kanematsu, Nobuyuki, Ito, Atsushi, Uchida, Hirohisa, Department of Accelerator and Medical Physics, Research Center for Charged Particle Therapy, National Institute of Radiological Sciences, 4-9-1 Anagawa, Inage-ku, Chiba 263-8555, Japan, and Tokyo Institute of Technology, Interdisciplinary Graduate School of Science and Engineering, 4259 Nagatsuta-cho, Midori-ku, Yokohama-shi, Kanagawa 226-8503, Tokyo Institute of Technology, Interdisciplinary Graduate School of Science and Engineering, 4259 Nagatsuta-cho, Midori-ku, Yokohama-shi, Kanagawa 226-8503, Department of Accelerator and Medical Physics, Research Center for Charged Particle Therapy, National Institute of Radiological Sciences, 4-9-1 Anagawa, Inage-ku, Chiba 263-8555, and Department of Energy Science and Engineering, School of Engineering, Tokai University, 1117 Kitakaname, Hiratsuka, Kanagawa 259-1292. Dose contributions from large-angle scattered particles in therapeutic carbon beams. United States: N. p., 2007. Web. doi:10.1118/1.2402328.
Kusano, Yohsuke, Kanai, Tatsuaki, Kase, Yuki, Matsufuji, Naruhiro, Komori, Masataka, Kanematsu, Nobuyuki, Ito, Atsushi, Uchida, Hirohisa, Department of Accelerator and Medical Physics, Research Center for Charged Particle Therapy, National Institute of Radiological Sciences, 4-9-1 Anagawa, Inage-ku, Chiba 263-8555, Japan, and Tokyo Institute of Technology, Interdisciplinary Graduate School of Science and Engineering, 4259 Nagatsuta-cho, Midori-ku, Yokohama-shi, Kanagawa 226-8503, Tokyo Institute of Technology, Interdisciplinary Graduate School of Science and Engineering, 4259 Nagatsuta-cho, Midori-ku, Yokohama-shi, Kanagawa 226-8503, Department of Accelerator and Medical Physics, Research Center for Charged Particle Therapy, National Institute of Radiological Sciences, 4-9-1 Anagawa, Inage-ku, Chiba 263-8555, & Department of Energy Science and Engineering, School of Engineering, Tokai University, 1117 Kitakaname, Hiratsuka, Kanagawa 259-1292. Dose contributions from large-angle scattered particles in therapeutic carbon beams. United States. doi:10.1118/1.2402328.
Kusano, Yohsuke, Kanai, Tatsuaki, Kase, Yuki, Matsufuji, Naruhiro, Komori, Masataka, Kanematsu, Nobuyuki, Ito, Atsushi, Uchida, Hirohisa, Department of Accelerator and Medical Physics, Research Center for Charged Particle Therapy, National Institute of Radiological Sciences, 4-9-1 Anagawa, Inage-ku, Chiba 263-8555, Japan, and Tokyo Institute of Technology, Interdisciplinary Graduate School of Science and Engineering, 4259 Nagatsuta-cho, Midori-ku, Yokohama-shi, Kanagawa 226-8503, Tokyo Institute of Technology, Interdisciplinary Graduate School of Science and Engineering, 4259 Nagatsuta-cho, Midori-ku, Yokohama-shi, Kanagawa 226-8503, Department of Accelerator and Medical Physics, Research Center for Charged Particle Therapy, National Institute of Radiological Sciences, 4-9-1 Anagawa, Inage-ku, Chiba 263-8555, and Department of Energy Science and Engineering, School of Engineering, Tokai University, 1117 Kitakaname, Hiratsuka, Kanagawa 259-1292. Mon . "Dose contributions from large-angle scattered particles in therapeutic carbon beams". United States. doi:10.1118/1.2402328.
@article{osti_20853909,
title = {Dose contributions from large-angle scattered particles in therapeutic carbon beams},
author = {Kusano, Yohsuke and Kanai, Tatsuaki and Kase, Yuki and Matsufuji, Naruhiro and Komori, Masataka and Kanematsu, Nobuyuki and Ito, Atsushi and Uchida, Hirohisa and Department of Accelerator and Medical Physics, Research Center for Charged Particle Therapy, National Institute of Radiological Sciences, 4-9-1 Anagawa, Inage-ku, Chiba 263-8555, Japan, and Tokyo Institute of Technology, Interdisciplinary Graduate School of Science and Engineering, 4259 Nagatsuta-cho, Midori-ku, Yokohama-shi, Kanagawa 226-8503 and Tokyo Institute of Technology, Interdisciplinary Graduate School of Science and Engineering, 4259 Nagatsuta-cho, Midori-ku, Yokohama-shi, Kanagawa 226-8503 and Department of Accelerator and Medical Physics, Research Center for Charged Particle Therapy, National Institute of Radiological Sciences, 4-9-1 Anagawa, Inage-ku, Chiba 263-8555 and Department of Energy Science and Engineering, School of Engineering, Tokai University, 1117 Kitakaname, Hiratsuka, Kanagawa 259-1292},
abstractNote = {In carbon therapy, doses at center of spread-out Bragg peaks depend on field size. For a small field of 5x5 cm{sup 2}, the central dose reduces to 96% of the central dose for the open field in case of 400 MeV/n carbon beam. Assuming the broad beam injected to the water phantom is made up of many pencil beams, the transverse dose distribution can be reconstructed by summing the dose distribution of the pencil beams. We estimated dose profiles of this pencil beam through measurements of dose distributions of broad uniform beams blocked half of the irradiation fields. The dose at a distance of a few cm from the edge of the irradiation field reaches up to a few percent of the central dose. From radiation quality measurements of this penumbra, the large-angle scattered particles were found to be secondary fragments which have lower LET than primary carbon beams. Carbon ions break up in beam modifying devices or in water phantom through nuclear interaction with target nuclei. The angular distributions of these fragmented nuclei are much broader than those of primary carbon particles. The transverse dose distribution of the pencil beam can be approximated by a function of the three-Gaussian form. For a simplest case of mono-energetic beam, contributions of the Gaussian components which have large mean deviations become larger as the depth in the water phantom increases.},
doi = {10.1118/1.2402328},
journal = {Medical Physics},
number = 1,
volume = 34,
place = {United States},
year = {Mon Jan 15 00:00:00 EST 2007},
month = {Mon Jan 15 00:00:00 EST 2007}
}
  • Purpose: It is essential to consider large-angle scattered particles in dose calculation models for therapeutic carbon-ion beams. However, it is difficult to measure the small dose contribution from large-angle scattered particles. In this paper, the authors present a novel method to derive the parameters describing large-angle scattered particles from the measured results. Methods: The authors developed a new parallel-plate ionization chamber consisting of concentric electrodes. Since the sensitive volume of each channel is increased linearly with this type, it is possible to efficiently and easily detect small contributions from the large-angle scattered particles. The parameters describing the large-angle scattered particlesmore » were derived from pencil beam dose distribution in water measured with the new ionization chamber. To evaluate the validity of this method, the correction for the field-size dependence of the doses, “predicted-dose scaling factor,” was calculated with the new parameters. Results: The predicted-dose scaling factor calculated with the new parameters was compared with the existing one. The difference between the new correction factor and the existing one was 1.3%. For target volumes of different sizes, the calculated dose distribution with the new parameters was in good agreement with the measured one. Conclusions: Parameters describing the large-angle scattered particles can be efficiently and rapidly determined using the new ionization chamber. The authors confirmed that the field-size dependence of the doses could be compensated for by the new parameters. This method makes it possible to easily derive the parameters describing the large-angle scattered particles, while maintaining the dose calculation accuracy.« less
  • Purpose: It is essential to consider large-angle scattered particles in dose calculation models for therapeutic carbon-ion beams. However, it is difficult to measure the small dose contribution from large-angle scattered particles. In this paper, the authors present a novel method to derive the parameters describing large-angle scattered particles from the measured results. Methods: The authors developed a new parallel-plate ionization chamber consisting of concentric electrodes. Since the sensitive volume of each channel is increased linearly with this type, it is possible to efficiently and easily detect small contributions from the large-angle scattered particles. The parameters describing the large-angle scattered particlesmore » were derived from pencil beam dose distribution in water measured with the new ionization chamber. To evaluate the validity of this method, the correction for the field-size dependence of the doses, “predicted-dose scaling factor,” was calculated with the new parameters. Results: The predicted-dose scaling factor calculated with the new parameters was compared with the existing one. The difference between the new correction factor and the existing one was 1.3%. For target volumes of different sizes, the calculated dose distribution with the new parameters was in good agreement with the measured one. Conclusions: Parameters describing the large-angle scattered particles can be efficiently and rapidly determined using the new ionization chamber. The authors confirmed that the field-size dependence of the doses could be compensated for by the new parameters. This method makes it possible to easily derive the parameters describing the large-angle scattered particles, while maintaining the dose calculation accuracy.« less
  • Purpose: Microdosimetric measurements were performed at Massachusetts General Hospital, Boston, MA, to assess the dose equivalent external to passively delivered proton fields for various clinical treatment scenarios. Methods and Materials: Treatment fields evaluated included a prostate cancer field, cranial and spinal medulloblastoma fields, ocular melanoma field, and a field for an intracranial stereotactic treatment. Measurements were completed with patient-specific configurations of clinically relevant treatment settings using a silicon-on-insulator microdosimeter placed on the surface of and at various depths within a homogeneous Lucite phantom. The dose equivalent and average quality factor were assessed as a function of both lateral displacement frommore » the treatment field edge and distance downstream of the beam's distal edge. Results: Dose-equivalent value range was 8.3-0.3 mSv/Gy (2.5-60-cm lateral displacement) for a typical prostate cancer field, 10.8-0.58 mSv/Gy (2.5-40-cm lateral displacement) for the cranial medulloblastoma field, 2.5-0.58 mSv/Gy (5-20-cm lateral displacement) for the spinal medulloblastoma field, and 0.5-0.08 mSv/Gy (2.5-10-cm lateral displacement) for the ocular melanoma field. Measurements of external field dose equivalent for the stereotactic field case showed differences as high as 50% depending on the modality of beam collimation. Average quality factors derived from this work ranged from 2-7, with the value dependent on the position within the phantom in relation to the primary beam. Conclusions: This work provides a valuable and clinically relevant comparison of the external field dose equivalents for various passively scattered proton treatment fields.« less
  • Many new techniques for delivering radiation therapy are being developed for the treatment of cancer. One of these, proton therapy, is becoming increasingly popular because of the precise way in which protons deliver dose to the tumor volume. In order to achieve this level of precision, extensive treatment planning needs to be carried out to determine the optimum beam energies, energy spread (which determines the width of the spread-out Bragg peak), and angles for each patient's treatment. Due to the level of precision required and advancements in computer technology, there is increasing interest in the use of Monte Carlo calculationsmore » for treatment planning in proton therapy. However, in order to achieve optimum simulation times, nonelastic nuclear interactions between protons and the target nucleus within the patient's internal structure are often not accounted for or are simulated using less accurate models such as analytical or ray tracing. These interactions produce high LET particles such as neutrons, alpha particles, and recoil protons, which affect the dose distribution and biological effectiveness of the beam. This situation has prompted an investigation of the importance of nonelastic products on depth dose distributions within various materials including water, A-150 tissue equivalent plastic, ICRP (International Commission on Radiological Protection) muscle, ICRP bone, and ICRP adipose. This investigation was conducted utilizing the GEANT4.5.2 Monte Carlo hadron transport toolkit.« less
  • Excitation functions for ..cap alpha.. + /sup 40/,/sup 44/Ca elastic scattering have been measured with bombarding energies in the range of 20--27 MeV in 50-keV steps at several angles between 150 and 175degree. For /sup 40/Ca excitation functions were also taken in 10-keV steps over a limited interval. Statistical fluctuations were observed in all the excitation functions and were found to be generally stronger for /sup 44/Ca than for /sup 40/Ca. An analysis of the fluctuations yields a relative compound contribution of about 2% for /sup 40/Ca and greater than about 5% for /sup 44/Ca. The backward enhancement in ..capmore » alpha.. + /sup 40/Ca scattering, observed by many previous workers, is shown to arise primarily from a direct contribution and not from a fluctuating compound one. (AIP)« less