Luminescence imaging during carbon-ion irradiation of water is not only possible but also a promising method for range estimation in carbon-ion therapy.
An overview of the electromagnetic (EM) physics of the Geant4 toolkit is presented. Two sets of EM models are available: the "Standard" initially focused on high energy physics (HEP) while the "Low-energy" was developed for medical, space and other applications. The "Standard" models provide a faster computation but are less accurate for keV energies, the "Low-energy" models are more CPU time consuming. A common interface to EM physics models has been developed allowing a natural combination of ultra-relativistic, relativistic and low-energy models for the same run providing both precision and CPU performance. Due to this migration additional capabilities become available. The new developments include relativistic models for bremsstrahlung and e+e-pair production, models of multiple and single scattering, hadron/ion ionization, microdosimetry for very low energies and also improvements in existing Geant4 models. In parallel, validation suites and benchmarks have been intensively developed.
Single-crystal particles of mesoporous niobium-tantalum mixed oxide with a wormholelike structure were successfully prepared and characterized. The mixed oxide was prepared by a neutral templating method, and the samples provided have thick walls and an unordered pore structure. Neutral block copolymer, HO(CH 2 CH 2 O) 20 (CH 2 CH(CH 3 )O) 70 (CH 2 CH 2 O) 20 H, and metal chlorides were used as the template and inorganic source in propanol. The crystallized mesoporous single-crystal structures were obtained by a two-step calcination process; the first calcination process removes the template, forming a mesoporous structure with amorphous wall material, and the second calcination process crystallizes the pore walls while maintaining the mesoporosity. The submicrometer mesoporous particles forming the walls were confirmed by transmission electron microscopy to be single crystals. The pore diameter was found to increase upon crystallization, while retaining the open-pore system. N 2 -gas adsorption-desorption analysis indicated that the pore volume of the crystallized sample remained the same as that of the amorphous precursor. The fabricated niobiumtantalum mixed oxide exhibits high thermal, hydrothermal, and mechanical stability.
PurposeSurgical spacer placement (SSP) is useful in particle therapy (PT) for patients with abdominal or pelvic tumors located adjacent to normal organs. We developed a nonwoven fabric bioabsorbable spacer made of polyglycolic acid (PGA) sutures that degrades via hydrolysis. We then conducted this first-in-human phase 1 study of the combination of SSP and PT using the PGA spacer, which we termed space-making PT (SMPT). This study aimed to evaluate the safety and efficacy of SMPT in patients with unresectable malignant tumor located adjacent to normal organs.Methods and MaterialsThe eligibility criteria included histologically proven malignant abdominal or pelvic tumor adjacent to the intestines, no metastasis, and no previous radiation therapy. Periodic computed tomography (CT) images were obtained before SSP and before, during, and after PT until the spacer disappeared. Treatment planning was performed for each CT image set until the end of PT, and doses for the planning target volume and organs at risk were analyzed. The thickness and volume of the PGA spacer were measured in each CT image set. Adverse events were evaluated according to the Common Terminology Criteria for Adverse Events version 4.0.ResultsFive patients were enrolled in this study. All patients received 70.4 Gy (relative biological effectiveness) of irradiation. V95% of the planning target volume before SSP, at the beginning of PT, and at the end of PT was 82.1% ± 11.3%, 98.1% ± 1.1%, and 97.1% ± 0.8%, respectively. The PGA spacers maintained enough thickness (≥1 cm) until the end of PT and disappeared within 8 months after SSP in all patients. No grade ≥3 acute adverse events were observed.ConclusionsThe SMPT is feasible and useful for abdominal or pelvic tumors adjacent to the intestines. This method may be applicable to unresectable tumors located adjacent to normal organs and may expand the indications of PT.
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