tajiama and yan Review

C-Ions 250 MeV/u
C-Ions 300 MeV/u
Rev. Accl. Sci. Tech. 2009.02:201-228. Downloaded from by PEKING UNIVERSITY on 09/26/13. For personal use only.
1. Introduction Advancement in the treatment of cancer is one of the major challenges in contemporary medicine and science at large. The number of deaths from cancer is increasing and this disease is the number-one cause of deaths in many countries. In Europe and America radiation treatment for cancer therapy is now applied in most cases (to more than 50% of patients) and in other countries it is increasing. For example, in Japan the percentage is currently around 20%. With the advent of superior diagnosis and early detection of cancer in the future, it is anticipated that this
201
trend toward increase in radiation therapy will continue [1]. What is the drive behind this trend? We would like to present here one possible school of thought for this based on an oncological consideration. This idea is based on the following observation [2–6]. Dr. Molls argues: “In chemotherapy the tumor cell kill depends on the transport of the substance to the clonogenic cells and molecular targets, DNA repair capacity, repopulation, pO2 , pH, MDR, etc. In macroscopic tumors not all the subvolumes of the tumor, clonogenic cells and relevant molecular targets are reached by those doses of the medical substance which are needed for cell kill. In other
Toshiki Tajima Fakult¨ at f¨ ur Physik, Ludwig-Maximilians-Universit¨ at M¨ unchen, Am Coulombwall 1, 85748 Garching, Germany and Photo-Medical Research Center, JAEA, Kyoto, 619-0215, Japan toshiki.tajima@physik.uni-muenchen.de Dietrich Habs Fakult¨ at f¨ ur Physik, Ludwig-Maximilians-Universit¨ at M¨ unchen, Am Coulombwall 1, 85748 Garching, Germany and Max-Planck-Institut f¨ ur Quantenoptik, Hans-Kopfermann-Str. 1, 85748 Garching, Germany Dietrich.Habs@physik.uni-muenchen.de Xueqing Yan Max-Planck-Institut f¨ ur Quantenoptik, Hans-Kopfermann-Str. 1, 85748 Garching, Germany and SKL of Nuclear Physics and Technology, Peking University, 100871, Beijing, China xyan@mpq.mpg.de Ion beam therapy for cancer has proven to be a successful clinical approach, affording as good a cure as surgery and a higher quality of life. However, the ion beam therapy installation is large and expensive, limiting its availability for public benefit. One of the hurdles is to make the accelerator more compact on the basis of conventional technology. Laser acceleration of ions represents a rapidly developing young field. The prevailing acceleration mechanism (known as target normal sheath acceleration, TNSA), however, shows severe limitations in some key elements. We now witness that a new regime of coherent acceleration of ions by laser (CAIL) has been studied to overcome many of these problems and accelerate protons and carbon ions to high energies with higher efficiencies. Emerging scaling laws indicate possible realization of an ion therapy facility with compact, cost-efficient lasers. Furthermore, dense particle bunches may allow the use of much higher collective fields, reducing the size of beam transport and dump systems. Though ultimate realization of a laser-driven medical facility may take many years, the field is developing fast with many conceptual innovations and technical progress. Keywords : Coherent acceleration of ions by laser (CAIL); target normal sheath acceleration (TNSA); radiation pressure acceleration (RPA); adiabatic acceleration; phase stable acceleration; ion beams; cancer therapy.
202
T. Tajima, D. Habs & X. Q. Yan
Rev. Accl. Sci. Tech. 2009.02:201-228. Downloaded from by PEKING UNIVERSITY on 09/26/13. For personal uon, “the chemotherapy dose distribution is intrinsically inhomogeneous.” On the other hand, Prof. Molls points out: “In radiation therapy the tumor cell kill depends on intrinsic radiation sensitivity, DNA repair capacity, repopulation, oxygenation status, etc. However, the entire tumor can be irradiated matched with the dose, which is necessary to kill all clonogenic tumor cells, even the most resistant ones.” In other words, “it delivers a matched dose distribution,” citing the superior feature of radiation therapy. Most (typically more than 90%) of current radiation therapy is based on photon therapy (using x-rays driven by accelerated electrons). This choice arose because of the technology available with the electron accelerator at an affordable cost and with a sufficiently compact setup. However, as is well known, most ionizing radiations, including x-rays, deposit a larger dose upon their entry or early propagation in the body than in their later propagation and at the all-important tumor site in the patient’s body. Such a dose is exponentially diminishing with penetration depth (see Fig. 1). Because of this property, in most