IBIC2014 - List of Authors (Saraya, Y.)

Paper	Title	Page
WEPF10	Range Verification System Using Scintillator and CCD Camera System	558
	N. S. Saotome, T. Furukawa, Y. Hara, K. Mizushima, K. Noda, T. Shirai, R. Tansho NIRS, Chiba-shi, Japan Y. Saraya National Institute of Radiological Sciences, Chiba, Japan
	At National Institute of Radiological Sciences (NIRS), three-dimensional irradiation with carbon-ion pencil-beam scanning has been performed from 2011. We have been commissioning the irradiation method that employs more than 200 multiple beam energies supplied by synchrotron instead of the energy degraders. The accuracy of the beam energy/range is required for heavy ion treatment especially for using scanning method. ICRU78 recommend checking the range constancy for daily QA. Few-points depth dose measurement using ion chamber is employed for range verification of current daily QA procedure in NIRS. The measurement time for one energy is about 1 minute. Therefore easy and simple range verification system is required. The purpose of this work is to develop range verification system using scintillator and CCD (charge-coupled device) camera and to estimate the accuracy of the range verification using the system. Using proposed system, projected depth dose distribution could be provided by one measurement. This system has potential to be employed for relative range check and range constancy check as comparing with reference data. A NE10² plastic scintillator block was selected for obtained pure tranceparent block. The scintillator was mounted in the black box in order to shade a light in the room. The CCD camera (Type BU-41L, 1360x1024 pixels, Bitran Corp., Japan) was installed perpendicular to the beam axis. Therefore two-dimensional image projected depth dose distribution is provided by measurement. Total 101 mono-energy carbon beams that are in the range from 56 to 430 MeV/n at 6 mm range-in-water interval were tested. The measurement was performed energy by energy sequentially. The range resolution test was performed using thin PMMA plate placed upstream of the system. Measured images were compared with reference images to calculate the relative range deviation using least square method. Short and long time reproducibility and fluence dependence were verified. Measurement time was about 2 minutes for 101 energy beams. Peak-entrance ratio was small due to quenching effect and absorption of the light within the scintillator block. The 6 mm range difference was clearly divided. Reproducibility was well. The difference of fluence with normal treatment operation didn’t effect the range verification. From the results it was concluded that the range check system using scintillator and CCD have nice characteristics for range verification with short time.
Export •	reference for this paper to ※ LaTeX, ※ Text, ※ IS/RefMan, ※ EndNote (xml)

WEPF23	Dosimetric Verification of Lateral Profile with a Unique Ionization Chamber in Therapeutic Ion Beams	597
	Y. Hara, T. Furukawa, K. Mizushima, K. Noda, N. S. Saotome, T. Shirai, R. Tansho NIRS, Chiba-shi, Japan Y. Saraya National Institute of Radiological Sciences, Chiba, Japan
	It is essential to consider large-angle scattered particles in dose calculation models for therapeutic ion beams. However, it is difﬁcult to measure the small dose contribution from large-angle scattered particles. Therefore, we developed a parallel-plate ionization chamber consisting of concentric electrodes (ICCE) to efﬁciently and easily detect small contributions. The ICCE consists of two successive ICs with a common HV plate. The former is a large plane-parallel IC to measure dose distribution integrated over the whole plane, the latter is a 24-channel parallel-plate IC with concentric electrodes to derive the characteristic parameters describing the lateral beam spread. The aim of this study is to evaluate the performance of the ICCE. By taking advantage of the characteristic of ICCE, we studied the recombination associated with lateral beam profile. Also, we measured carbon pencil beam in several different media by using ICCE. As a result, we confirmed the ICCE could be used as a useful tool to determine the characterization of the therapeutic ion beams.
Export •	reference for this paper to ※ LaTeX, ※ Text, ※ IS/RefMan, ※ EndNote (xml)

WEPF24	Development of Three-Dimensional Dose Verification System using a Fluorescent Screen in Ion Beam Therapy	601
	Y. Hara, T. Furukawa, K. Mizushima, K. Noda, N. S. Saotome, T. Shirai, E. Takeshita, R. Tansho NIRS, Chiba-shi, Japan Y. Saraya National Institute of Radiological Sciences, Chiba, Japan
	For quality assurance (QA) of therapeutic ion beams, QA tool having high spatial resolution and quick verification is required. The imaging system with a fluorescent screen is suitable for QA procedure. We developed a quick veriﬁcation system (NQA-SCN) using a ﬂuorescent screen with a charge-coupled device (CCD) camera for the sake of two dimensional dosimetry. In carbon-ion therapy, the ﬂuorescent light is decreased by suffering from quenching effect due to the increased linear energy transfer (LET) in the Bragg peak. For the use of three-dimensional dose verification, we performed a simple correction for quenching effect and several types of corrections for the optical artifact. In addition, NQA-SCN is attached with an accordion-type water phantom which makes it possible to easily change measurement depth. To evaluate the performance of NQA-SCN, we carried out experiments concerning QA procedures. In my presentation, we provide correction methods and detailed analysis of measured results.
Export •	reference for this paper to ※ LaTeX, ※ Text, ※ IS/RefMan, ※ EndNote (xml)

WEPF30	Study of General Ion Recombination for Beam Monitor used in Particle Radiotherapy	620
	R. Tansho, T. Furukawa, Y. Hara, K. Mizushima, K. Noda, N. S. Saotome, T. Shirai NIRS, Chiba-shi, Japan Y. Saraya National Institute of Radiological Sciences, Chiba, Japan
	Heavy ion particles such as carbon ion beams are effective tools for cancer radiotherapy because of the higher dose localization and biological effectiveness by using the characteristic dose distribution with the Bragg peak. In the particle radiotherapy, it is important to conform a dose distribution and deliver prescribed dose to a tumor. An ionization chamber is usually used as a beam monitor to control the prescribed dose to the target. Then new treatment research facility at National Institute of Radiological Science (NIRS) uses beam scanning irradiation system that make uniform dose distribution in the target volume by superposing dose deposit of an individual pencil beam. In order to increase dose concentration to the target and also decrease irradiation time, it is necessary to minimize the pencil beam size and to increase the beam intensity. As the result, the localization of the pencil beam with high intensity increases the number of general ion recombination in the beam monitor. Therefore, we need to predict the ion recombination rate in the beam monitor for accurate control of the dose. For our purpose, we developed calculation code to predict the ion recombination rate when the pencil beam scanning is used. The calculation code can divide a pencil beam into a sub region and calculate ion recombination rate in each sub region by using Boag theory. We present the calculation results compared with measurements for verification of our calculation code.
Export •	reference for this paper to ※ LaTeX, ※ Text, ※ IS/RefMan, ※ EndNote (xml)

Paper

Title

Page

Range Verification System Using Scintillator and CCD Camera System

558

N. S. Saotome, T. Furukawa, Y. Hara, K. Mizushima, K. Noda, T. Shirai, R. Tansho
NIRS, Chiba-shi, Japan
Y. Saraya
National Institute of Radiological Sciences, Chiba, Japan

At National Institute of Radiological Sciences (NIRS), three-dimensional irradiation with carbon-ion pencil-beam scanning has been performed from 2011. We have been commissioning the irradiation method that employs more than 200 multiple beam energies supplied by synchrotron instead of the energy degraders. The accuracy of the beam energy/range is required for heavy ion treatment especially for using scanning method. ICRU78 recommend checking the range constancy for daily QA. Few-points depth dose measurement using ion chamber is employed for range verification of current daily QA procedure in NIRS. The measurement time for one energy is about 1 minute. Therefore easy and simple range verification system is required. The purpose of this work is to develop range verification system using scintillator and CCD (charge-coupled device) camera and to estimate the accuracy of the range verification using the system. Using proposed system, projected depth dose distribution could be provided by one measurement. This system has potential to be employed for relative range check and range constancy check as comparing with reference data. A NE10² plastic scintillator block was selected for obtained pure tranceparent block. The scintillator was mounted in the black box in order to shade a light in the room. The CCD camera (Type BU-41L, 1360x1024 pixels, Bitran Corp., Japan) was installed perpendicular to the beam axis. Therefore two-dimensional image projected depth dose distribution is provided by measurement. Total 101 mono-energy carbon beams that are in the range from 56 to 430 MeV/n at 6 mm range-in-water interval were tested. The measurement was performed energy by energy sequentially. The range resolution test was performed using thin PMMA plate placed upstream of the system. Measured images were compared with reference images to calculate the relative range deviation using least square method. Short and long time reproducibility and fluence dependence were verified. Measurement time was about 2 minutes for 101 energy beams. Peak-entrance ratio was small due to quenching effect and absorption of the light within the scintillator block. The 6 mm range difference was clearly divided. Reproducibility was well. The difference of fluence with normal treatment operation didn’t effect the range verification. From the results it was concluded that the range check system using scintillator and CCD have nice characteristics for range verification with short time.

Export •

reference for this paper to ※ LaTeX, ※ Text, ※ IS/RefMan, ※ EndNote (xml)

WEPF23

Dosimetric Verification of Lateral Profile with a Unique Ionization Chamber in Therapeutic Ion Beams

597

Y. Hara, T. Furukawa, K. Mizushima, K. Noda, N. S. Saotome, T. Shirai, R. Tansho
NIRS, Chiba-shi, Japan
Y. Saraya
National Institute of Radiological Sciences, Chiba, Japan

It is essential to consider large-angle scattered particles in dose calculation models for therapeutic ion beams. However, it is difﬁcult to measure the small dose contribution from large-angle scattered particles. Therefore, we developed a parallel-plate ionization chamber consisting of concentric electrodes (ICCE) to efﬁciently and easily detect small contributions. The ICCE consists of two successive ICs with a common HV plate. The former is a large plane-parallel IC to measure dose distribution integrated over the whole plane, the latter is a 24-channel parallel-plate IC with concentric electrodes to derive the characteristic parameters describing the lateral beam spread. The aim of this study is to evaluate the performance of the ICCE. By taking advantage of the characteristic of ICCE, we studied the recombination associated with lateral beam profile. Also, we measured carbon pencil beam in several different media by using ICCE. As a result, we confirmed the ICCE could be used as a useful tool to determine the characterization of the therapeutic ion beams.

Export •

reference for this paper to ※ LaTeX, ※ Text, ※ IS/RefMan, ※ EndNote (xml)

WEPF24

Development of Three-Dimensional Dose Verification System using a Fluorescent Screen in Ion Beam Therapy

601

Y. Hara, T. Furukawa, K. Mizushima, K. Noda, N. S. Saotome, T. Shirai, E. Takeshita, R. Tansho
NIRS, Chiba-shi, Japan
Y. Saraya
National Institute of Radiological Sciences, Chiba, Japan

For quality assurance (QA) of therapeutic ion beams, QA tool having high spatial resolution and quick verification is required. The imaging system with a fluorescent screen is suitable for QA procedure. We developed a quick veriﬁcation system (NQA-SCN) using a ﬂuorescent screen with a charge-coupled device (CCD) camera for the sake of two dimensional dosimetry. In carbon-ion therapy, the ﬂuorescent light is decreased by suffering from quenching effect due to the increased linear energy transfer (LET) in the Bragg peak. For the use of three-dimensional dose verification, we performed a simple correction for quenching effect and several types of corrections for the optical artifact. In addition, NQA-SCN is attached with an accordion-type water phantom which makes it possible to easily change measurement depth. To evaluate the performance of NQA-SCN, we carried out experiments concerning QA procedures. In my presentation, we provide correction methods and detailed analysis of measured results.

Export •

reference for this paper to ※ LaTeX, ※ Text, ※ IS/RefMan, ※ EndNote (xml)

WEPF30

Study of General Ion Recombination for Beam Monitor used in Particle Radiotherapy

620

R. Tansho, T. Furukawa, Y. Hara, K. Mizushima, K. Noda, N. S. Saotome, T. Shirai
NIRS, Chiba-shi, Japan
Y. Saraya
National Institute of Radiological Sciences, Chiba, Japan

Heavy ion particles such as carbon ion beams are effective tools for cancer radiotherapy because of the higher dose localization and biological effectiveness by using the characteristic dose distribution with the Bragg peak. In the particle radiotherapy, it is important to conform a dose distribution and deliver prescribed dose to a tumor. An ionization chamber is usually used as a beam monitor to control the prescribed dose to the target. Then new treatment research facility at National Institute of Radiological Science (NIRS) uses beam scanning irradiation system that make uniform dose distribution in the target volume by superposing dose deposit of an individual pencil beam. In order to increase dose concentration to the target and also decrease irradiation time, it is necessary to minimize the pencil beam size and to increase the beam intensity. As the result, the localization of the pencil beam with high intensity increases the number of general ion recombination in the beam monitor. Therefore, we need to predict the ion recombination rate in the beam monitor for accurate control of the dose. For our purpose, we developed calculation code to predict the ion recombination rate when the pencil beam scanning is used. The calculation code can divide a pencil beam into a sub region and calculate ion recombination rate in each sub region by using Boag theory. We present the calculation results compared with measurements for verification of our calculation code.

Export •

reference for this paper to ※ LaTeX, ※ Text, ※ IS/RefMan, ※ EndNote (xml)