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Title: Improvement of the Kei2 source for a new carbon therapy facility

Abstract

A compact electron cyclotron resonance ion source with all permanent magnets has been developed for a new carbon therapy facility at NIRS. Initial tests with the Kei2 source have given a maximum intensity of 530 e {mu}A for C{sup 4+} at an extraction voltage of 40 kV and beam stability of better than 6% for 90 h at 280 e {mu}A at 30 kV. In these beam tests, there was continuously unwanted discharge around the puller at high-voltage extraction (above 40 kV). The start of discharge is caused by the short distance of 5 mm between the end of the plasma chamber and puller. At high-voltage extraction, this discharge will give rise to unwanted vapor from the copper puller. Then, the vacuum pressure in the extraction region will become worse. In order to suppress the discharge, the plasma chamber and puller were modified. Finally, a beam intensity of 380 e {mu}A was obtained with good stability at an extraction voltage of 30 kV. This article describes the modification of the puller for stable beam extraction, measurements of beam emittance, and improvement of C{sup 4+} intensity.

Authors:
; ; ; ; ; ; ; ; ;  [1];  [2];  [2];  [2];  [3]
  1. Graduate School of Mechanical Engineering, Toyo University, 2100 Kujirai, Kawagoe, Saitama 350-0815 (Japan) and National Institute of Radiological Sciences, 4-9-1 Anagawa, Inage, Chiba 263-8555 (Japan)
  2. (Japan)
  3. (Netherlands)
Publication Date:
OSTI Identifier:
20778947
Resource Type:
Journal Article
Resource Relation:
Journal Name: Review of Scientific Instruments; Journal Volume: 77; Journal Issue: 3; Conference: 11. international conference on ion sources, Caen (France), 12-16 Sep 2005; Other Information: DOI: 10.1063/1.2151902; (c) 2006 American Institute of Physics; Country of input: International Atomic Energy Agency (IAEA)
Country of Publication:
United States
Language:
English
Subject:
43 PARTICLE ACCELERATORS; BEAM EMITTANCE; BEAM EXTRACTION; CARBON; CARBON IONS; ECR ION SOURCES; PARTICLE BEAMS; PERMANENT MAGNETS; STABILITY; THERAPY

Citation Formats

Muramatsu, M., Kitagawa, A., Ogawa, Hirotsugu, Iwata, Y., Yamamoto, K., Yamada, S., Ogawa, Hiroyuki, Fujimoto, T., Yoshida, Y., Drentje, A., National Institute of Radiological Sciences, 4-9-1 Anagawa, Inage, Chiba 263-8555, Accelerator Engineering Corporation, Ltd., 2-13-1 Konakadai, Inage, Chiba 263-0043, Department of Mechanical Engineering, Toyo University, 2100 Kujirai, Kawagoe, Saitama 350-0815, and K.V.I., University of Groningen, 9747 AA Groningen. Improvement of the Kei2 source for a new carbon therapy facility. United States: N. p., 2006. Web. doi:10.1063/1.2151902.
Muramatsu, M., Kitagawa, A., Ogawa, Hirotsugu, Iwata, Y., Yamamoto, K., Yamada, S., Ogawa, Hiroyuki, Fujimoto, T., Yoshida, Y., Drentje, A., National Institute of Radiological Sciences, 4-9-1 Anagawa, Inage, Chiba 263-8555, Accelerator Engineering Corporation, Ltd., 2-13-1 Konakadai, Inage, Chiba 263-0043, Department of Mechanical Engineering, Toyo University, 2100 Kujirai, Kawagoe, Saitama 350-0815, & K.V.I., University of Groningen, 9747 AA Groningen. Improvement of the Kei2 source for a new carbon therapy facility. United States. doi:10.1063/1.2151902.
Muramatsu, M., Kitagawa, A., Ogawa, Hirotsugu, Iwata, Y., Yamamoto, K., Yamada, S., Ogawa, Hiroyuki, Fujimoto, T., Yoshida, Y., Drentje, A., National Institute of Radiological Sciences, 4-9-1 Anagawa, Inage, Chiba 263-8555, Accelerator Engineering Corporation, Ltd., 2-13-1 Konakadai, Inage, Chiba 263-0043, Department of Mechanical Engineering, Toyo University, 2100 Kujirai, Kawagoe, Saitama 350-0815, and K.V.I., University of Groningen, 9747 AA Groningen. Wed . "Improvement of the Kei2 source for a new carbon therapy facility". United States. doi:10.1063/1.2151902.
@article{osti_20778947,
title = {Improvement of the Kei2 source for a new carbon therapy facility},
author = {Muramatsu, M. and Kitagawa, A. and Ogawa, Hirotsugu and Iwata, Y. and Yamamoto, K. and Yamada, S. and Ogawa, Hiroyuki and Fujimoto, T. and Yoshida, Y. and Drentje, A. and National Institute of Radiological Sciences, 4-9-1 Anagawa, Inage, Chiba 263-8555 and Accelerator Engineering Corporation, Ltd., 2-13-1 Konakadai, Inage, Chiba 263-0043 and Department of Mechanical Engineering, Toyo University, 2100 Kujirai, Kawagoe, Saitama 350-0815 and K.V.I., University of Groningen, 9747 AA Groningen},
abstractNote = {A compact electron cyclotron resonance ion source with all permanent magnets has been developed for a new carbon therapy facility at NIRS. Initial tests with the Kei2 source have given a maximum intensity of 530 e {mu}A for C{sup 4+} at an extraction voltage of 40 kV and beam stability of better than 6% for 90 h at 280 e {mu}A at 30 kV. In these beam tests, there was continuously unwanted discharge around the puller at high-voltage extraction (above 40 kV). The start of discharge is caused by the short distance of 5 mm between the end of the plasma chamber and puller. At high-voltage extraction, this discharge will give rise to unwanted vapor from the copper puller. Then, the vacuum pressure in the extraction region will become worse. In order to suppress the discharge, the plasma chamber and puller were modified. Finally, a beam intensity of 380 e {mu}A was obtained with good stability at an extraction voltage of 30 kV. This article describes the modification of the puller for stable beam extraction, measurements of beam emittance, and improvement of C{sup 4+} intensity.},
doi = {10.1063/1.2151902},
journal = {Review of Scientific Instruments},
number = 3,
volume = 77,
place = {United States},
year = {Wed Mar 15 00:00:00 EST 2006},
month = {Wed Mar 15 00:00:00 EST 2006}
}
  • A high-energy carbon-ion radiotherapy facility is under construction at Gunma University Heavy Ion Medical Centre (GHMC). Its design was based on a study of the heavy ion radiotherapy at the National Institute of Radiological Sciences (NIRS) in order to reduce the size and construction cost of the facility. A compact electron cyclotron resonance ion source (ECRIS) for Gunma University, called KeiGM, was installed in 2008. It is almost a copy of the prototype ECRIS Kei2 which was developed by NIRS; meanwhile this prototype produced over 1 e mA of C{sup 4+} using C{sub 2}H{sub 2} gas (660 W and 40more » kV). The beam intensity of C{sup 4+} was 600 e {mu}A with CH{sub 4} gas (250 W and 30 kV). The beam intensity satisfies the required value of 300 e {mu}A.« less
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  • Purpose: This study explores the possibility of using lead to cover part of the radiation therapy facility maze walls in order to absorb low energy photons and reduce the total dose at the maze entrance of radiation therapy rooms. Methods: Experiments and Monte Carlo simulations were utilized to establish the possibility of using high-Z materials to cover the concrete walls of the maze in order to reduce the dose of the scattered photons at the maze entrance. The dose of the backscattered photons from a concrete wall was measured for various scattering angles. The dose was also calculated by themore » FLUKA and EGSnrc Monte Carlo codes. The FLUKA code was also used to simulate an existing radiotherapy room to study the effect of multiple scattering when adding lead to cover the concrete walls of the maze. Monoenergetic photons were used to represent the main components of the x ray spectrum up to 10 MV. Results: It was observed that when the concrete wall was covered with just 2 mm of lead, the measured dose rate at all backscattering angles was reduced by 20% for photons of energy comparable to Co-60 emissions and 70% for Cs-137 emissions. The simulations with FLUKA and EGS showed that the reduction in the dose was potentially even higher when lead was added. One explanation for the reduction is the increased absorption of backscattered photons due to the photoelectric interaction in lead. The results also showed that adding 2 mm lead to the concrete walls and floor of the maze reduced the dose at the maze entrance by up to 90%. Conclusions: This novel proposal of covering part or the entire maze walls with a few millimeters of lead would have a direct implication for the design of radiation therapy facilities and would assist in upgrading the design of some mazes, especially those in facilities with limited space where the maze length cannot be extended to sufficiently reduce the dose.« less
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