IBIC2012 - List of Authors (Takeshita, E.)

Paper	Title	Page
MOPB58	Beam Quality Ensuring Instruments at the Gunma University Heavy-ion Medical Center	209
	E. Takeshita, T. Kanai, M. Kawashima, Y. Kubota, A. Matsumura, A. Saito, H. Shimada, M. Tashiro, K. Torikai, S. Yamada, K. Yusa Gunma University, Heavy-Ion Medical Research Center, Maebashi-Gunma, Japan
	Since the carbon beam based cancer therapy started at the Gunma University Heavy-ion Medical Center in the year 2010, the total number of treated patients increased to 306 by the end of fiscal 2011. This year, already 82 patients have been treated. In order to control the medical beam qualities, i.e., position, size and intensity of the beam, monitoring devices were mounted on the high-energy beam transport line. The beam position and size can be measured and tuned with a screen monitor, which consists of a fluorescent screen and a CCD camera. Just before starting the treatment, the operators check for a proper beam position by strip-line monitor measurements placed close to the iso center. The irradiation dose is controlled using two secondary electron emission monitors placed before the wobbling magnets. This dose monitor is helpful for high fluence of the beam because it's less affected by the recombination effect. In the conference, we would like to report on details of each monitoring device.

MOPB51	Beam Monitors of NIRS Fast Scanning System for Particle Therapy	182
	T. Furukawa, Y. Hara, T. Inaniwa, K. Katagiri, K. Mizushima, K. Noda, S. Sato, T. Shirai, E. Takeshita NIRS, Chiba-shi, Japan
	At National Institute of Radiological Sciences, more than 6500 patients have been successfully treated by carbon beams since 1994. The successful results of treatments have led us to construct a new treatment facility equipped with three-dimensional pencil beam scanning irradiation system. The commissioning of NIRS fast scanning system installed into the new facility was started in September 2010, and the treatment with scanned ion beam was started in May 2011. In the scanning delivery system, beam monitors are some of the most important components. In order to measure and control the dose of each spot, the main and the sub ionization chambers are placed separately as flux monitors. For monitoring of the scanned beam position, a beam position monitor, which is multi-wire proportional chamber, is installed just downstream from the flux monitors. This monitor can output not only the beam position but also the 2D fluence distribution using dynamic fast convolution algorithm. In this paper, the design and the commissioning of these monitors are described.

MOPB76	Evaluation of a Fluorescent Screen with a CCD System for Quality Assurance in Heavy-Ion Beam Scanning Irradiation System	249
	Y. Hara, T. Furukawa, T. Inaniwa, K. Mizushima, K. Noda, S. Sato, T. Shirai, E. Takeshita NIRS, Chiba-shi, Japan
	The precise heavy-ion therapy such as the scanning irradiation system necessitates the precise quality assurance (QA) procedures to verify the performance of therapeutic scanned ion beams. To evaluate the uniformity of the 2D field, radiographic film is used due to its high spatial resolution and suit for the measurements of the integral dose. However, this technique is time consuming. Thus, we developed the QA tool with high spatial resolution to verify accuracy of the lateral size, position and uniformity of scanned ion beams in clinical application at the HIMAC, which we called the QA-SCN. The QA-SCN consists of a fluorescent screen, a CCD camera, a mirror, camera controllers and a dark box to protect against surrounding light. In this paper, to evaluate the performance of the QA-SCN, we compared the results obtained by using it with the measurements by radiographic film performed in the same experimental conditions. Also, we verified several types of corrections about errors, e.g. background, vignetting, to distort the measurement results. As a result, we confirmed that the QA-SCN can be used as the system for QA procedures of therapeutic scanned ion beams.

MOPB78	Beam Spot Measurement using a Phosphor Screen for Carbon-Ion Therapy at NIRS	256
	K. Mizushima, T. Furukawa, Y. Hara, K. Katagiri, K. Noda, T. Shirai, E. Takeshita NIRS, Chiba-shi, Japan
	A two-dimensional beam imaging system with a terbium-doped gadolinium oxysulfide (Gd2O2S:Tb) phosphor screen and high-speed charge coupled device (CCD) camera has been used to measure the beam spot for scanned carbon-ion therapy at National Institute of Radiological Sciences (NIRS). The system enables us to obtain one image of the beam spot every 20 milliseconds. The fluctuation of the unscanned-beam spot size and position was observed in the isocenter to verify the time stability of the delivered beam for scanning irradiation. The beam imaging system also functions as a beam alignment adjustment system by setting a steel sphere at the isocenter. For quality assurance, the beam alignment is routinely checked by observing a shadow of the steel sphere on the beam spot image, and it is confirmed that the misalignment of the beam is smaller than the tolerance of 0.5 mm.

Paper

Title

Page

Beam Quality Ensuring Instruments at the Gunma University Heavy-ion Medical Center

209

E. Takeshita, T. Kanai, M. Kawashima, Y. Kubota, A. Matsumura, A. Saito, H. Shimada, M. Tashiro, K. Torikai, S. Yamada, K. Yusa
Gunma University, Heavy-Ion Medical Research Center, Maebashi-Gunma, Japan

Since the carbon beam based cancer therapy started at the Gunma University Heavy-ion Medical Center in the year 2010, the total number of treated patients increased to 306 by the end of fiscal 2011. This year, already 82 patients have been treated. In order to control the medical beam qualities, i.e., position, size and intensity of the beam, monitoring devices were mounted on the high-energy beam transport line. The beam position and size can be measured and tuned with a screen monitor, which consists of a fluorescent screen and a CCD camera. Just before starting the treatment, the operators check for a proper beam position by strip-line monitor measurements placed close to the iso center. The irradiation dose is controlled using two secondary electron emission monitors placed before the wobbling magnets. This dose monitor is helpful for high fluence of the beam because it's less affected by the recombination effect. In the conference, we would like to report on details of each monitoring device.

MOPB51

Beam Monitors of NIRS Fast Scanning System for Particle Therapy

182

T. Furukawa, Y. Hara, T. Inaniwa, K. Katagiri, K. Mizushima, K. Noda, S. Sato, T. Shirai, E. Takeshita
NIRS, Chiba-shi, Japan

At National Institute of Radiological Sciences, more than 6500 patients have been successfully treated by carbon beams since 1994. The successful results of treatments have led us to construct a new treatment facility equipped with three-dimensional pencil beam scanning irradiation system. The commissioning of NIRS fast scanning system installed into the new facility was started in September 2010, and the treatment with scanned ion beam was started in May 2011. In the scanning delivery system, beam monitors are some of the most important components. In order to measure and control the dose of each spot, the main and the sub ionization chambers are placed separately as flux monitors. For monitoring of the scanned beam position, a beam position monitor, which is multi-wire proportional chamber, is installed just downstream from the flux monitors. This monitor can output not only the beam position but also the 2D fluence distribution using dynamic fast convolution algorithm. In this paper, the design and the commissioning of these monitors are described.

MOPB76

Evaluation of a Fluorescent Screen with a CCD System for Quality Assurance in Heavy-Ion Beam Scanning Irradiation System

249

Y. Hara, T. Furukawa, T. Inaniwa, K. Mizushima, K. Noda, S. Sato, T. Shirai, E. Takeshita
NIRS, Chiba-shi, Japan

The precise heavy-ion therapy such as the scanning irradiation system necessitates the precise quality assurance (QA) procedures to verify the performance of therapeutic scanned ion beams. To evaluate the uniformity of the 2D field, radiographic film is used due to its high spatial resolution and suit for the measurements of the integral dose. However, this technique is time consuming. Thus, we developed the QA tool with high spatial resolution to verify accuracy of the lateral size, position and uniformity of scanned ion beams in clinical application at the HIMAC, which we called the QA-SCN. The QA-SCN consists of a fluorescent screen, a CCD camera, a mirror, camera controllers and a dark box to protect against surrounding light. In this paper, to evaluate the performance of the QA-SCN, we compared the results obtained by using it with the measurements by radiographic film performed in the same experimental conditions. Also, we verified several types of corrections about errors, e.g. background, vignetting, to distort the measurement results. As a result, we confirmed that the QA-SCN can be used as the system for QA procedures of therapeutic scanned ion beams.

MOPB78

Beam Spot Measurement using a Phosphor Screen for Carbon-Ion Therapy at NIRS

256

K. Mizushima, T. Furukawa, Y. Hara, K. Katagiri, K. Noda, T. Shirai, E. Takeshita
NIRS, Chiba-shi, Japan

A two-dimensional beam imaging system with a terbium-doped gadolinium oxysulfide (Gd2O2S:Tb) phosphor screen and high-speed charge coupled device (CCD) camera has been used to measure the beam spot for scanned carbon-ion therapy at National Institute of Radiological Sciences (NIRS). The system enables us to obtain one image of the beam spot every 20 milliseconds. The fluctuation of the unscanned-beam spot size and position was observed in the isocenter to verify the time stability of the delivered beam for scanning irradiation. The beam imaging system also functions as a beam alignment adjustment system by setting a steel sphere at the isocenter. For quality assurance, the beam alignment is routinely checked by observing a shadow of the steel sphere on the beam spot image, and it is confirmed that the misalignment of the beam is smaller than the tolerance of 0.5 mm.