Search

The RF-knockout (RF-KO) slow-extraction method with frequency modulation (FM) and amplitude modulation (AM) has brought high-accuracy irradiation to the treatment of a cancer tumor moving with respiration, because of a quick response to beam start/stop. However, a beam spill extracted from a synchrotron ring through RF-KO slow-extraction has a huge ripple with a frequency of around 1 kHz related to the FM. The spill ripple will disturb the lateral dose distribution in the beam scanning methods. Thus, the source of the spill ripple has been investigated through experiments and simulations. There are two tune regions for the extraction process through the RF-KO method: the extraction region and the diffusion region. The particles in the extraction region can be extracted due to amplitude growth through the transverse RF field, only when its frequency matches with the tune in the extraction region. For a large chromaticity, however, the particles in the extraction region can be extracted through the synchrotron oscillation, even when the frequency does not match with the tune in the extraction region. Thus, the spill structure during one period of the FM strongly depends on the horizontal chromaticity. They are repeated with the repetition frequency of the FM, which is the very source of the spill ripple in the RF-KO method.

The magnetic moment of the short-lived β emitter 35Ar ( I π =3/2 + , T 1/2 =1.77 s) has been remeasured by means of the combined technique of polarized nuclear beams and β-NMR. The obtained magnetic moment is 0.6322(2) μN. This value is consistent with the old data, but is one order of more magnitude precise. The value is well reproduced by the shell model calculation.

In cancer treatment with heavy ions, verification of the ion range in the patient's body is important. For this purpose, a positron emitter beam provides the possibility of range verification. To use the positron emitter beam, we have constructed a secondary beam course and its irradiation system. In this paper the constructed system is presented together with some results of beam experiments.

The magnetic dipole (μ) and electric quadrupole (Q) moments of short-lived nucleus 22F ( I π = 4 + , T 1 / 2 = 4.2 s ) have been measured for the first time by means of the β-NMR technique. A spin polarized 22F beam was produced through the charge exchange reaction of 22Ne and was implanted into single crysltals of NaF and MgF2 for μ and Q measurements, respectively. As a result, | μ ( F 22 ) | = ( 2.69443 ± 0.00039 ) μ N and | Q ( F 22 ) | = ( 3 ± 2 ) mb was obtained. These values are well reproduced by the shell model calculations.

The spin lattice-relaxation rates of short-lived unstable nuclei Al 25 and P 28 in Pt has been measured by means of the β-NMR technique, in order to study the electronic structure of dilute impurities in Pt. From the obtained spin-lattice relaxation rates, Knight shifts K c were estimated to be K c [ Al in Pt ] = ( 0.45 ± 0.09 ) × 10 − 3 and K c [ P in Pt ] = ( 4 − 4 + 2 ) × 10 − 3 using the Korringa relation. These values were evaluated by comparing to the first principle calculations.

Nuclear structure of proton-rich unstable nucleus 28P has been studied by measuring its g-factor for the first time. The g-factor of 28P (Iπ = 3+, T1/2 = 270.3 ms) was measured by means of β-NMR technique combined with the new polarization technique for charge exchange reaction product in the intermediate energy heavy ion collisions. The obtained g-factor of g = 0.1028(27) is very much quenched from the Schmidt value, but is well reproduced by the shell model (+0.102). In connection with the magnetic moment of the mirror partner and the β-ray transition probability, the orbital angular momenta and intrinsic spins of protons and neutrons have been determined as 〈lp〉 = 0.43(29), 〈ln〉 = 1.85(29), 〈Sp) = 0.28(4), and 〈Sn〉 = 0.44(4).

Heavy-Ion Medical Accelerator in Chiba (HIMAC) provides ion beams for radiotherapy of cancers and for other basic researches. High-energy beam transport lines deliver the beams to three treatment rooms and two experiment rooms with the aid of 41 beam monitor units. Each monitor unit consists of a wire grid as a profile monitor, or a combined unit in which the wire grid and a parallel plate ionization chamber are united for an additional measurement of a beam intensity. They are operated in a mixed gas of 80% Ar and 20% CO2. The gas gain of the wire grid achieves about 8000 at an applied voltage of −2700 V. Dynamic ranges of the wire gird and the parallel plate ionization chamber were measured to be 8×105 and 1×106 in test using ion beams, respectively. A control system of these monitor units offers easy operation, so that operators are almost free from miss-operations. The monitor units are interlocked with a system which protects patients from the undesired irradiation. Five wire grids are used for continuously monitoring the beam during treatments, which play a role in keeping qualities of the treatments. The monitor system has been designed to meet requirements for medical uses, and works in a stable and reliable manner and satisfies the requirements.

ions has been observed through measurements of the surviving charge state of Arions planar channeled in a Si crystal. We experimentally demonstrate trajectory-dependent, i.e., impactparameter dependent resonant-coherent-excitation phenomena by measuring the energy deposition incoincidence with the charge state of emerging ions. The resonant-coherent-excitation transition energyreflects spin-orbit

Resonant coherent excitation of the 1s electron to na 2 states in a hydrogen-like ion was studied through measurements of the survived fraction of 390 MeV/u Ar 17a planar channeled in a Si crystal. Adopting a totally depleted Si surface barrier detector as a target crystal, the charge state of the individual emerged ion was measured in coincidence with the energy deposition in the target. By changing the incident direction along theO2 20 U ,O 004 U, andO1 11 Uplanes, a series of clear resonances were observed as the decrease in the survived charge fraction due to higher electron loss probability for the excited state. Each resonance profile reflects energy splitting of the na 2 manifold originated from l‐ s interaction and Stark eAect due to the crystal field. From the correlation between the energy loss and survived charge fraction, transition energy as a function of the ion trajectory amplitude is deduced which is in good agreement with calculated results. ” 1998 Elsevier Science B.V. All rights reserved.

We have succeeded in observing the channeling of 290 MeV/u C 6+ ions in a Si crystal. Under 〈1 1 0〉 axial, and (0 0 4), (2 2 0) and (1 1 1) planar channeling conditions, energy loss of the channeled ion in the Si crystal was observed. We also calculated the trajectory dependent stopping power for planar channeling ions, which employs mean and local electron densities evaluated adopting the Moliere potential. Calculated energy loss spectra were found to reproduce the experimental results quite well.

We observed resonant coherent excitation (RCE) of 1s electron to n=2 states in Ar17+ through measurements of the survived fraction of 390 MeV/u hydrogen-like Ar17+ channeled in a Si crystal. We adopted a totally depleted Si surface barrier detector as a target crystal as well as a probe of the energy deposition. The charge state of emerged ions was measured by a combination of a charge separation magnet and a 2D-position sensitive detector. We observed the RCE for planar channeled ions by tilting the target Si crystal from the direction of [1 1 0] axis in the (2 2 0) , (0 0 4) , and (1 1 1) planes. Prominent resonances at tilt angles under the resonance condition were observed. Moreover, each resonance profile is split into several lines due to the l·s interaction and the Stark effect originating in the static crystal field. The energy deposition in the crystal gives the information of the amplitude of the ion trajectory. The resonance peak position, intensity and width in the survived fraction of Ar17+ reflect the position dependent strength of the crystal field, the RCE and the electron loss probabilities. They are in good accord with our calculation of the transition energy and probability.

Researchers explore the use of Bragg Ionization Peak in radiotherapy for tumors. Considerations for the production of a high quality radioactive beam include secondary beam production efficiency, primary beam survival, and multiple scattering. A Positron Emitting Beam Analyzing camera was developed and tested at BEVALAC using a neon-19 beam stopping point. Results indicate that in homogeneous brain tissues, CT measurements and radioactive beam measurements are between 1-2 mm; there can be substantial difference between CT measurements and radioactive beam estimates if the beam stopping point crosses the fossae; random coincidences due to detector activation also appear as diffused images in the image plane of the beam stopping point; and further enhancements are necessary to make reliable measurements in the human trunk and complex brain regions.

A beam extraction method using a transverse rf electric field with amplitude and frequency modulation has been studied in order to develop an irradiation method which is synchronized with the breathing of a patient for high-quality charged particle therapy. The dependence of the extracted beam intensity on the voltage, the frequency band width and the center frequency of the transverse rf electric field has been investigated. The extracted beam intensity was slightly increased from that of the ordinary slow extraction method with a third order resonance. The response of the extracted beam intensity to the applied transverse rf electric field was as prompt as within 1 ms. The horizontal emittance of beams extracted by the present method was reduced by about 70% compared with that by the ordinary one due to utilizing a constant separatrix. Amplitude modulation can control the global beam spill structure. The frequency modulation reduced the effect of the current ripple of the main quadrupole magnets.

The NIRS heavy-ion two-synchrotron medical facility, HIMAC, was approved in the 1987 fiscal year and clinical trials were started in late June 1994 as previously arranged. The operation experiences show that the entire HIMAC facility can work well with high stability and excellent reproducibility. For example, the intensity of beam extracted slowly from the rings can be reduced as low as 500 particles per pulse because stable and reproducible acceleration can be achieved in the rings in spite of no beam feedback. This performance enables direct counting of the beam and its fragments in the preparatory experiments toward clinical treatments and provides a promising basis for acceleration and storage of radioactive beams toward simultaneous treatment and diagnosis in future.

Information on electron density is important for radiotherapy treatment planning in order to optimize the dose distribution in the target volume of a patient. At present, the electron density is derived from a computed tomography (CT) number measured in x-ray CT scanning; however, there are uncertainties due to the beam hardening effect and the method by which the electron density is converted from the CT number. In order to measure the electron density with an accuracy of +/-1%, the authors have developed dual-energy x ray CT using monochromatic x rays. They experimentally proved that the measured linear attenuation coefficients were only a few percent lower than the theoretical ones, which led to an accuracy within 2% for the electron density. There were three factors causing inaccuracy in the linear attenuation coefficient and the electron density: the influence of scattered radiation, the nonlinearity in the detector response function, and a theoretical process to derive the electron density from the linear attenuation coefficients. The linear attenuation coefficients of water were experimentally proved to differ by 1%-2% from the theoretical one even when the scattering effect was negligible. The nonlinearity of the response function played an important role in correcting the difference in the linear attenuation coefficient. Furthermore, the theoretical process used for deriving the electron density from the linear attenuation coefficients introduces about 0.6% deviation from the theoretical value into the resultant electron density. This deviation occurs systematically so that it can be corrected. The authors measured the electron densities for seven samples equivalent to soft tissue in dual-energy x-ray CT, and finally obtained them with an accuracy of around +/-1%.

A model for beam customization with collimators and a range-compensating filter based on the phase-space theory for beam transport is presented for dose distribution calculation in treatment planning of radiotherapy with protons and heavier ions. Independent handling of pencil beams in conventional pencil-beam algorithms causes unphysical collimator-height dependence in the middle of large fields, which is resolved by the framework comprised of generation, transport, collimation, regeneration, range-compensation, and edge-sharpening processes with a matrix of pencil beams. The model was verified to be consistent with measurement and analytic estimation at a submillimeter level in penumbra of individual collimators with a combinational-collimated carbon-ion beam. The model computation is fast, accurate, and readily applicable to pencil-beam algorithms in treatment planning with capability of combinational collimation to make best use of the beam-customization devices., 16 pages, 5 figures

We measured the polarization of the β‐emitting 23Ne (Iπ = 5/2+, T1/2 = 37.24 s) and 25Al(Iπ = 5/2+, T1/2 = 7.18 s), produced through the one nucleon pickup reactions in the intermediate energy heavy ion collisions, and was compared with those from the projectile fragmentation process. The larger polarization which seems to persistently be positive throughout the momentum distribution, and sharper momentum distributions suggest nuclear friction mechanism to be responsible for the polarization phenomena. Using such a large polarization, magnetic moment of 23Ne and the quadrupole moment of 25Al were measured. The obtained values are |μ(23Ne)| = 1.0817(9) μN and |Q(25Al)| = (240 ± 20) mb.

The commissioning of conformal radiotherapy system using heavy-ion beams at the Heavy Ion Medical Accelerator in Chiba (HIMAC) is described in detail. The system at HIMAC was upgraded for a clinical trial using a new technique: large spot uniform scanning with conformal layer stacking. The system was developed to localize the irradiation dose to the target volume more effectively than with the old system. With the present passive irradiation method using a ridge filter, a scatterer, a pair of wobbler magnets, and a multileaf collimator, the width of the spread-out Bragg peak (SOBP) in the radiation field could not be changed. With dynamic control of the beam-modifying devices during irradiation, a more conformal radiotherapy could be achieved. In order to safely perform treatments with this conformal therapy, the moving devices should be watched during irradiation and the synchronousness among the devices should be verified. This system, which has to be safe for patient irradiations, was constructed and tested for safety and for the quality of the dose localization realized. Through these commissioning tests, we were successfully able to prepare the conformal technique using layer stacking for patients. Subsequent to commissioning the technique has been applied to patients in clinical trials.

Numerical studies on the effect of a superconducting wiggler (SCW), which was developed at National Institute of Radiological Sciences (NIRS), to Saga light source (SAGA-LS) have been performed. The three dimensional magnetic field of the SCW was calculated to evaluate the effect on beam optics. It was found that the tune correction was needed to reduce a deformation of the vertical beta function. The dynamic aperture shrank to about 70 % on horizontal plane. However these effects are considered to be tolerable at the SAGA-LS.

β‐NMR spectra have been observed for 33Cl, 23Al and 23Ne. As a result, the magnetic moment of 33Cl was determined as |μ(33Cl)| = 0.7549(3) μN. Combined with the known magnetic moment of 33S and the ft‐value of the 33Cl β decay, the orbital angular momenta and the intrinsic spins for proton and neutron groups, are deduced separately as 〈lp〉 = 1.3, 〈n〉 = 0.3, 〈Sp〉 = −0.12 and 〈Sn〉 = −0.02. The magnetic moment of 23Al, and that of 23Ne were determined as |μ(23Al)| = 3.89(22) μN and |μ(23Ne)| = 1.0817(9) μN, respectively. As a result, the orbital angular momentum 〈lz〉 and the intrinsic spin 〈Sz〉 were deduced to be 2.09(29) and 0.41(29), respectively. Combined with the ft‐value of the β transition from the ground state of 23Al to the excited state of 23Mg, proton and neutron contributions are separated. The obtained expectation values 〈lp〉, 〈ln〉, 〈Sp〉 and 〈Sn〉 are compared with the shell model predictions.

Monochromatic x-ray CT at two different energies provides information about electron density without ambiguity due to the beam hardening effect. This information makes the treatment planning for heavy-ion radiotherapy more precise. We have started a feasibility study on the dual-energy x-ray CT by using synchrotron radiation. We developed a linear scanning CT system(1D-CT) in order to evaluate what precision in the measurement was achieved. Comparison fo measured electron densities with the theoretical values proved that these values were in afreement in 0.9 % on average. We haave developed a 2D-CT system with a two-dimensional scintillator array to take images in a short time. At present, it has been proved that the electron density is measured in the precision of about 1 %. Effectove atomic numbers are obtained as well from the dual-energy x-ray CT. They present a different feature of an object, and the contrasts in the images differ from that in a conventional CT image. The feature of the images may help distinguish more clearly tissues or organs with aid of difference contrast from the conventional CT images., International Symposium on Portable Synchrotron Light Sources and Advanced Applications

The electron density is one of the most important elements for the treatment planning in the radiotherapy, because this information is used for the range estimation of the heavy‐ion beam. In order to measure more precise electron density, we have developed the dual‐energy x‐ray CT system using synchrotron radiation. The x‐ray detector consists of 256 × 96 scintillator‐array. It can take more than a hundred projection images per second. The response of the detector to x‐rays was proved to be linear up to at least 1013 photon/pixel. The experiments were carried out using two monochromatic x‐rays of 40 keV and 70 keV at the beam‐line BL20B2 of SPring‐8. As the results from samples of water, ethanol and solutions of dipotassium hydrogenphosphate with five concentrations, the electron densities measured in the dual‐energy x‐ray CT method were in agreement with the theoretical values by about ± 1%. This is almost the same level as that achieved by the one‐dimensional CT system we developed previously. In addition, a sample of kidney of a pig fixed by formalin neutral buffer solution was used to distinguish the tissues in the CT images based on the electron density and the effective atomic number that was additionally obtained in the dual‐energy x‐ray CT. It suggested that renal pelvis was enriched with adipose tissue, and it was difficult to distinguish renal cortex and renal medulla.

The relationship between resolution of human vessels and radiation dose in micro‐angiography was evaluated. The radiation dose required to visualize vessels increased as a function of the −4th power of the resolution of vessel images. Since vessels are overlapped in angiograms, resolution of the target vessel is poor. We discuss resolution of 1 mm vessels in selective angiography.

A synchrotron light source dedicated to medical applica- tions has been designed at National Institute of Radiological Sciences. The storage ring, with circumference of 80 m, is designed for accel- eration of 2.3 GeV and a stored current of 420 mA. It is equipped with two multipole wigglers to produce sufficient photon flux in a hard x-ray region required for medical applications. The purposes of the synchrotron light source are clinical performance of medical diag- noses clinically and research and development relating with medical applications. One of the most interesting applications for us is dual- energy x-ray computed tomography (CT). It gives the information about electron density of human tissue. The information plays an im- portant role in advancing heavy-ion radiotherapy of cancers. Electron density can be derived from attenuation coefficients measured by dif- ferent energy x rays. In this paper, a practical method of the dual- energy x-ray CT with synchrotron radiation is proposed with the theoretical consideration. The primitive experiment using monochro- matic x rays emitted from radioisotopes proved the procedure of analysis mentioned here effective to derive electron densities from linear attenuation coefficients for two x rays of a different energy. The beamline dedicated to dual-energy x-ray CT is also proposed. It has a multipole wiggler as a light source and it mainly consists of a dual crystal monochromator and a rotating filter for attenuating photon flux of x rays and two-dimensional detector. © 2001 Society of Photo-Optical In

A synchrotron light source dedicated to medical applications is designed at NIRS. The synchrotron ring accelerates electrons up to 1.8 GeV and stores them with about 400 mA, and is equipped with two superconducting multipole wigglers to generate sufficient photon flux for medical diagnoses. One of the most interesting applications for us is monochromatic x-ray computed tomography (CT). It plays an important role in advancing heavy ion radiotherapy of cancers which is being performed at NIRS. The radiotherapy is carried out based on a treatment planning which is a protocol for irradiation of the heavy ion beam on a target to maximize dose distribution and a biological advantage. The treatment planning converts CT-number of tissues along paths of the heavy ion beam to electron densities in order to calculated end-of-range of the heavy ion beam. The conventional x-ray CT introduces uncertainty into the CT- numbers due to beam hardening effect. While the monochromatic x-ray makes the CT-scan free from the beam hardening effect. Furthermore, dual energy x-ray CT-scans give the electron density directly without conversion from the CT-number. We focus on the x-ray CT using two monochromatic x-rays, and outline its beamline and the compact ring.

A synchrotron light source dedicated to medical applications is required to be compact for installation in limited spaces at hospitals. The NIRS storage ring, with a circumference of 44.8 m, is designed to accelerate electrons up to 1.8 GeV and to store a beam of 400 mA. The ring is composed of superconducting bending magnets for downsizing. A beam of 300 MeV is injected into the ring from a microtron operated at an L-band RF frequency. There are two superconducting multipole wigglers with nine poles and a maximum field of 8 T, which can produce a photon flux of about 1.4 × 1013 photons s−1 mrad−1 (0.1% bandwidth)−1 at 33 keV used for coronary angiography.

The electric quadrupole coupling constant eqQ/h of 25Na (Iπ = 5/2+, T1/2 = 59.6 s), implanted in a TiO2 single crystal, has been measured by use of the β-NMR technique, to determine the electric quadrupole moment Q. As a result, |eqQ/h| = (44 ± 16) kHz and |Q(25Na)| = (1.0 ± 0.4) mb were determined. From the NMR on 25Na in NaCl, the magnetic moment was determined as |µ| = (3.6832 ± 0.0003) µN

The branching ratio of the isomeric γ decay of 24mAl has been measured to be 69.6(7)% which is much smaller than the previously accepted value of 82.5(30)%. As a result, the branching ratio to the 24Mg ground state increases up to 24.1(7)% assuming that the other β-decay branching ratios are the previously accepted values. The half-life of 24mAl was also precisely determined to be 130.9(13) ms. The B(GT) value from the ground state of 24Mg to the 24mAl of 0.0577(16) deduced from the β decay is now in good agreement with that deduced from charge-exchange reactions.

Purpose: This work is aimed to improve the computational model of the beam‐customization devices for treatment planning of radiotherapy with heavy charged particles, where only a single collimator and a compensator have been commonly handled with inaccuracy of unphysical collimator dependence in the middle of large fields. Method and Materials: The phase‐space theory is applied to the beam transport through the beam‐customization devices to enable handling of multiple collimators and a compensator in any order. The theoretical model was experimentally tested with a carbon‐ion beam, where two jaw and a multileaf collimators, a 3‐cm PMMA half plate for a range compensator, and an 8‐cm square aperture for a patient collimator were concurrently used. In the model, a matrix of pencil beams was transported through the devices and a two‐dimensional in‐air dose distribution on the isocenter plane was computed within ten seconds. For comparison, the penumbra sizes at the field edges formed by the effective collimators were analytically estimated and the dose profiles along four axes on the isocenter plane were experimentally measured. Results: The model computation agreed with the measurement and analytic estimation at a submillimeter level in penumbra size and reproduced the measured dose fluctuation in the middle of the field due to the range‐compensator scatter. Conclusion: The model computation is fast, accurate, and readily applicable to pencil‐beam algorithms in treatment planning to enable combinational collimation for the best use of beam‐customization devices.

For medical irradiation, beams with a uniform distribution have been required. We have proposed a method to control the beam profile using an octupole magnet. We have installed an octupole magnet and confirmed its effectiveness at the Heavy Ion Medical Accelerator in Chiba (HIMAC) beam-transport line. A beam efficiency of 91% can be realized with a flatness of ±4% over the range of ±15 mm. The beam offset at the position of the octupole magnet is required to be within ±0.2 mm to realize this condition. This method is expected to have a beam efficiency higher than that of the ordinary method using wobbler magnets and a scatterer system.

Interactions of relativistic clothed heavy ions with solid targets have been studied for 390 MeV/u Ar17+ ions traversing carbon foils of various thicknesses through measurements of the convoy electrons. The electron energy spectra at 0° were obtained by a magnetic analyzer combined with a Si surface barrier detector with a depletion layer of 5 mm. The peak widths of the convoy electrons in the laboratory frame have been found to decrease as the target thickness is increased from 25 to about 500 µg/cm2, and broaden for thicker targets due to multiple scattering.

We measured the energy loss of charge-frozen clothed ions (i.e., partially stripped ions which maintain their charge states throughout the passage) in a Si solid employing a totally depleted silicon detector with 4.1 µm thickness as a target, to measure the energy deposition of 390 MeV/u Ar17+ directly. Under the present conditions, the probability of the electron loss is not so large, and that of the electron capture is negligibly small. Accordingly, the energy loss of charge-frozen Ar17+ ions in a rather thick target can be measured. Charge states of ions transmitted through the target were observed by a 2D-position sensitive detector in coincidence with the energy deposition. We have obtained an effective charge of Ar17+ ions for the stopping power, as Zeff = 17.36 (±0.03).

The energy distribution of pions produced from 16 O bombarded with 200 MeV electron was measured. The angular distribution of 16 O(γ,π + ) 16 N was deduced for the pions leading to the sum of the four lowest lying residual levels. The cross section integrated over angles is compared with the previous data deduced from the photopion yield curve. Experimental cross sections are compared with the shell model and Helm model predictions. The shell model results with configuration mixing approximately reproduce the present experimental results. The Helm model results are also similar to the experimental angular distribution pertterns.

The information on the electron densities of bodies is important for the treatment planning of radiotherapy. In order to obtain the electron densities directly, we have developed dual-energy X-ray computed tomography (CT) using synchrotron radiation. It was experimentally proved that the electron density was deduced with about 1% accuracy from two linear attenuation coefficient. However, the linear attenuation coefficient were measured by a few percent lower than the theoretical ones. We assumed that the less accurate linear attenuation coefficients were caused by the influence of scattered radiation and the non-linearity in the response of the detector. In comparison of the scattered radiation to the simulation results, the scattered radiation contributed at the most 0.5% to the linear attenuation coefficients. Correcting the non-linearity in the detector response functions, the values of linear attenuation coefficient were improved drastically.

We have developed a parallel beam suitable for channeling experiments with relativistic heavy ions at HIMAC (Heavy Ion Medical Accelerator in Chiba). To observe channeling phenomena, we used a silicon surface barrier detector (SSD) as a sample crystal and as a detector for the energy loss in itself. Further, we measured the angular spread of the beam transmitted through the SSD by a position sensitive detector (PSD) placed downstream of the SSD. Under axial and (111), (220) and (004) planar channeling conditions, we observed that the energy loss of the channeled ions in the SSD became almost a half and their angular spread was also reduced.

The momentum distributions of projectile-like fragments produced in the 40 Ar+ 9 Be reaction at E / A =90 MeV and the 16 O+ 12 C reaction at E / A =290 MeV were observed. A correlation between the width of the transverse momentum distribution and the velocity was found at E / A =90 MeV. Coulomb final-state interaction and AMD calculation cannot explain this correlation. A good agreement between EPAX2 and the production cross sections derived from observed momentum distribution of the fragments was found.

Over 3000 cancer patients have already been treated with 140- to 400-MeV/n carbon beams produced by the heavy ion medical accelerator in Chiba (HIMAC) at the National Institute of Radiological Sciences (NIRS) since 1994. These clinical results have clearly verified the advantages of carbon ions. Based on our experience at HIMAC, a hospital-specific facility optimized for carbon-ion therapy has been designed. The prototype developments of an electron cyclotron resonance (ECR) ion source, a radio frequency quadruple (RFQ) linac, an inter digital H (IH) linac, an acceleration system of synchrotron, a beam-delivery system and other key-technology parts have been successfully finished. Thus, in co-operation with NIRS, Gunma University has been constructing a carbon-therapy facility since April, 2006. If the present clinical results are to be improved, it is necessary to create a more accurate dose distribution on tumors without an undesired dose being deposited in normal tissue. Beam-scanning methods with respiration-gated irradiation are especially important to treat a cancer tumor located in the trunk of a patient.