A geometrical model for the Monte Carlo simulation of the TrueBeam linac

Monte Carlo (MC) simulation of linacs depends on the accurate geometrical description of the head. The geometry of the Varian TrueBeam (TB) linac is not available to researchers. Instead, the company distributes phase-space files (PSFs) of the flattening-filter-free (FFF) beams tallied upstream the jaws. Yet, MC simulations based on third party tallied PSFs are subject to limitations. We present an experimentally-based geometry developed for the simulation of the FFF beams of the TB linac. The upper part of the TB linac was modeled modifying the Clinac 2100 geometry. The most important modification is the replacement of the standard flattening filters by ad hoc thin filters which were modeled by comparing dose measurements and simulations. The experimental dose profiles for the 6MV and 10MV FFF beams were obtained from the Varian Golden Data Set and from in-house measurements for radiation fields ranging from 3X3 to 40X40 cm2. Indicators of agreement between the experimental data and the simulation results obtained with the proposed geometrical model were the dose differences, the root-mean-square error and the gamma index. The same comparisons were done for dose profiles obtained from MC simulations using the second generation of PSFs distributed by Varian for the TB linac. Results of comparisons show a good agreement of the dose for the ansatz geometry similar to that obtained for the simulations with the TB PSFs for all fields considered, except for the 40X40 cm2 field where the ansatz geometry was able to reproduce the measured dose more accurately. Our approach makes possible to: (i) adapt the initial beam parameters to match measured dose profiles; (ii) reduce the statistical uncertainty to arbitrarily low values; and (iii) assess systematic uncertainties by employing different MC codes

Monte Carlo simulation of the treatment of eye tumors with 106 Ru plaques: A study on maximum tumor height and eccentric placement

Background/Aims: Ruthenium plaques are used for the treatment of ocular tumors. There is, however, a controversy regarding the maximum treatable tumor height. Some advocate eccentric plaque placement, without a posterior safety margin, to avoid collateral damage to the fovea and optic disc, but this has raised concerns about marginal tumor recurrence. There is a need for quantitative information on the spatial absorbed dose distribution in the tumor and adjacent tissues. We have overcome this obstacle using an approach based on Monte Carlo simulation of radiation transport. Methods: CCA and CCB 106Ru plaques were modeled and their geometry embedded in a computerized tomography scan of the eye of a patient. Different tumor sizes and locations were simulated with the general-purpose Monte Carlo code PENELOPE. Results: Cumulative dose-volume histograms were obtained for the tumors and the tissues at risk considered. Plots of isodose lines for both plaques were obtained in a computerized tomography study. Conclusions: Ruthenium eye plaques are an adequate treatment option for tumors up to around 5 mm in height. According to our results, assuming a correct placement of the plaque, a tumor of 6.5 mm apical height is about the maximum size that can be treated safely with the large CCB plaque.Postprint (published version

Advances in Superconductivity as a road to meet Energy and Health SDGs: joint Japanese and European research teams may take the lead

Based on a statistical analysis of R&D activities in the field of superconductivity (SC) in a broad sense, the paper reports that Japan's leadership is strong over the past 20 years, in terms of researchers publications and patents. It also essentially shows that among the main world players, the Japanese normalized contribution is significantly dominating, although some trend towards a diminished leadership is observed in the data over the period 2005 -present time. Finally, the paper highlights that by taking advantage of their internationally recognized expertise in the field, joint Japanese and European research teams may advance superconductivity as a reliable road to meet Energy and Health SDGs (Sustainable Development Goals -UNESCO 2015)

Theranostics in Boron Neutron Capture Therapy

Boron neutron capture therapy (BNCT) has the potential to specifically destroy tumor cells without damaging the tissues infiltrated by the tumor. BNCT is a binary treatment method based on the combination of two agents that have no effect when applied individually: B-10 and thermal neutrons. Exclusively, the combination of both produces an effect, whose extent depends on the amount of B-10 in the tumor but also on the organs at risk. It is not yet possible to determine the B-10 concentration in a specific tissue using non-invasive methods. At present, it is only possible to measure the B-10 concentration in blood and to estimate the boron concentration in tissues based on the assumption that there is a fixed uptake of B-10 from the blood into tissues. On this imprecise assumption, BNCT can hardly be developed further. A therapeutic approach, combining the boron carrier for therapeutic purposes with an imaging tool, might allow us to determine the B-10 concentration in a specific tissue using a non-invasive method. This review provides an overview of the current clinical protocols and preclinical experiments and results on how innovative drug development for boron delivery systems can also incorporate concurrent imaging. The last section focuses on the importance of proteomics for further optimization of BNCT, a highly precise and personalized therapeutic approach

Theranostics in Boron Neutron Capture Therapy

Boron neutron capture therapy (BNCT) has the potential to specifically destroy tumor cells without damaging the tissues infiltrated by the tumor. BNCT is a binary treatment method based on the combination of two agents that have no effect when applied individually: 10B and thermal neutrons. Exclusively, the combination of both produces an effect, whose extent depends on the amount of 10B in the tumor but also on the organs at risk. It is not yet possible to determine the 10B concentration in a specific tissue using non-invasive methods. At present, it is only possible to measure the 10B concentration in blood and to estimate the boron concentration in tissues based on the assumption that there is a fixed uptake of 10B from the blood into tissues. On this imprecise assumption, BNCT can hardly be developed further. A therapeutic approach, combining the boron carrier for therapeutic purposes with an imaging tool, might allow us to determine the 10B concentration in a specific tissue using a non-invasive method. This review provides an overview of the current clinical protocols and preclinical experiments and results on how innovative drug development for boron delivery systems can also incorporate concurrent imaging. The last section focuses on the importance of proteomics for further optimization of BNCT, a highly precise and personalized therapeutic approach

Theranostics in Boron neutron capture therapy

Boron neutron capture therapy (BNCT) has the potential to specifically destroy tumor cells without damaging the tissues infiltrated by the tumor. BNCT is a binary treatment method based on the combination of two agents that have no effect when applied individually:B and thermal neutrons. Exclusively, the combination of both produces an effect, whose extent depends on the amount ofB in the tumor but also on the organs at risk. It is not yet possible to determine theB concentration in a specific tissue using non-invasive methods. At present, it is only possible to measure theB concentration in blood and to estimate the boron concentration in tissues based on the assumption that there is a fixed uptake ofB from the blood into tissues. On this imprecise assumption, BNCT can hardly be developed further. A therapeutic approach, combining the boron carrier for therapeutic purposes with an imaging tool, might allow us to determine theB concentration in a specific tissue using a non-invasive method. This review provides an overview of the current clinical protocols and preclinical experiments and results on how innovative drug development for boron delivery systems can also incorporate concurrent imaging. The last section focuses on the importance of proteomics for further optimization of BNCT, a highly precise and personalized therapeutic approach.E.H.-H. and M.K. gratefully acknowledge support from the DFG (HE 1376/38-1); L.S. received funding from GEFLUC Grenoble Dauphiné Savoie

Endoluminal beta-radiation therapy for the prevention of coronary restenosis after balloon angioplasty.

BACKGROUND: Beta radiation is effective in reducing vascular neointimal proliferation in animals after injury caused by balloon angioplasty. However, the lowest dose that can prevent restenosis after coronary angioplasty has yet to be determined. METHODS: After successful balloon angioplasty of a previously untreated coronary stenosis, 181 patients were randomly assigned to receive 9, 12, 15, or 18 Gy of radiation delivered by a centered yttrium-90 source. Adjunctive stenting was required in 28 percent of the patients. The primary end point was the minimal luminal diameter six months after treatment, as a function of the delivered dose of radiation. RESULTS: At the time of follow-up coronary angiography, the mean minimal luminal diameter was 1.67 mm in the 9-Gy group, 1.76 mm in the 12-Gy group, 1.83 mm in the 15-Gy group, and 1.97 mm in the 18-Gy group (P=0.06 for the comparison of 9 Gy with 18 Gy), resulting in restenosis rates of 29 percent, 21 percent, 16 percent, and 15 percent, respectively (P=0.14 for the comparison of 9 Gy with 18 Gy). At that time, 86 percent of the patients had had no serious cardiac events. In 130 patients treated with balloon angioplasty alone, restenosis rates were 28 percent, 17 percent, 16 percent, and 4 percent, respectively (P=0.02 for the comparison of 9 Gy with 18 Gy). Among these patients, there was a dose-dependent enlargement of the lumen in 28 percent, 50 percent, 45 percent, and 74 percent of patients, respectively (P<0.001 for the comparison of 9 Gy with 18 Gy). The rate of repeated revascularization was 18 percent with 9 Gy and 6 percent with 18 Gy (P=0.26). CONCLUSIONS: Intracoronary beta radiation therapy produces a significant dose-dependent decrease in the rate of restenosis after angioplasty. An 18-Gy dose not only prevents the renarrowing of the lumen typically observed after successful balloon angioplasty, but actually induces luminal enlargement

Use of Linear Programming to Obtain an Optimum, Multi-Beam Treatment Plan in BNCT

For BNCT of melanoma metastases in the brain, it has been necessary to calculate the dose distributions in the patient for dozens of possible neutron beams and then to combine manually the different beams by individually weighting and adding them. This time consuming approach eventually gave the required treatment plan, which satisfied the prescription dose. However, by linear optimisation with the Simplex method, the optimum weights for a set of beams can be determined mathematically. The objective function to maximise is the minimum averaged physical boron dose in one certain lesion for every set of beams. The maximisation of this objective function is performed under the constraints of certain maximum and minimum dose limits in the organs at risk and lesions respectively and restricting the set of weighted beams to deliver an average total weighted dose of 7 Gy in the brain. After iteration, by using the constraint set for the minimum dose in the lesions as a variable and performed for all combinations of the neutron beams, the optimum beams and weights are found for each treatment. As a preliminary result, the total irradiation time decreased by more than 30%, which is advantageous regarding both the pharmacokinetics of the boron in the patient and patient comfort.JRC.F.3-High Flux and Future Reactor