Development and characterization of optical readout well-type glass gas electron multiplier for dose imaging in clinical carbon beams

The use of carbon ion beams in cancer therapy (also known as hadron therapy) is steadily growing worldwide; therefore, the demand for more efficient dosimetry systems is also increasing because daily quality assurance (QA) measurements of hadron radiotherapy is one of the most complex and time consuming tasks. The aim of this study is to develop a two-dimensional dosimetry system that offers high spatial resolution, a large field of view, quick data response, and a linear dose–response relationship.We demonstrate the dose imaging performance of a novel digital dose imager using carbon ion beams for hadron therapy. The dose imager is based on a newly-developed gaseous detector, a well-type glass gas electron multiplier. The imager is successfully operated in a hadron therapy facility with clinical intensity beams for radiotherapy. It features a high spatial resolution of less than 1 mm and an almost linear dose–response relationship with no saturation and very low linear-energy-transfer dependence. Experimental results show that the dose imager has the potential to improve dosimetry accuracy for daily QA.     

Clinical implications of different calculation algorithms in breast radiotherapy: A comparison between pencil beam and collapsed cone convolution

BackgroundThis investigation focused on the clinical implications of the use of the Collapsed Cone Convolution algorithm (CCC) in breast radiotherapy and investigated the dosimetric differences as respect to Pencil Beam Convolution algorithm (PBC).Material and methods15 breast treatment plans produced using the PBC algorithm were re-calculated using the CCC algorithm with the same MUs. In a second step, plans were re-optimized using CCC algorithm with modification of wedges and beam weightings to achieve optimal coverage (CCCr plans). For each patient, dosimetric comparison was performed using the standard tangential technique (SWT) and a forward-planned IMRT technique (f-IMRT).ResultsThe CCC algorithm showed significant increased dose inhomogeneity. Mean and minimum PTV doses decreased by 1.4% and 2.8% (both techniques). Mean V95% decreased to 83.7% and 90.3%, respectively for the SWT and f-IMRT. V95% was correlated to the ratio of PTV and lung volumes into the treatment field. The re-optimized CCCr plans achieved similar target coverage, but high-dose volume was significantly larger (V107%: 7.6% vs 2.3% (SWT), 7.1% vs 2.1% (f-IMRT). There was a significantly increase in the ipsilateral lung volume receiving low doses (V5 Gy: 31.3% vs 26.2% in SWT, 27.0% vs 23.0% in f-IMRT). MUs needed for PTV coverage in CCCr plans were higher by 3%.ConclusionsThe PBC algorithm overestimated PTV coverage in terms of all important dosimetric metrics. If previous clinical experience are based on the use of PBC model, especially needed is discussion between medical physicists and radiation oncologists to fully understand the dosimetric changes.     

An approach for vat color printing on cotton and polyester fabrics with electron beam irradiation curable formulations

Accelerated electrons delivered by electron beam accelerator were used to fix vat colors, incorporated in curable formulations containing diluting monomer and an oligomer, to cellulosic fabric, cotton and polyester fabric. Tetrahydrofurfuryl acrylate, hexane dioldiacrylate, monomers and trifunctional urethane methacrylate, oligomer were used as curable base beside ethylene glycol. The fabrics were printed with these formulations and exposed to various doses of electron beam irradiation generated from the 1.5 MeV (25 kW) electron beam accelerator machine. Critical factors included the irradiation dose, formulation composition, and vat color concentration were studied. The fabrics printed with the vat colors by electron beam irradiation displayed higher color yield than those fabrics printed by the conventional curing at equal vat color ratios. The durable properties of fabrics printed by electron beam irradiation except the roughness properties are extremely better than those printed by conventional fixation method.     

Proton beam and prostate cancer: An evolving debate

This paper evaluates the reasons behind the rise in the use of proton beam for prostate cancer, the economics drivers behind it, and the evidence that exists to support it. It concludes that clinical outcome data underlying the notion that this is a superior treatment remains sparse and discusses what is needed to fill in the gaps.     

Optimization of synchrotron based ion beam therapy facilities for treatment time reduction,options and the MedAustron development roadmap

A faster treatment reduces the risk of intra-fraction movement of organs, offers a more comfortable treatment to the patient, allows to treat lesion of larger volumes in a reasonable time and most of all expands the capacity of the facility.This work presents possible machine upgrades for synchrotron based ion beam therapy centers to shorten the irradiation time. The expected delivery times for each scenario are simulated for the study case of proton beams of MedAustron.The second part of the work focuses on the MedAustron development roadmap, where recently increase of ring fillings and delivered intensities were implemented for proton treatments achieving an average irradiation time of ~50% since start of operation.