Medipix3 proton and carbon ion measurements across full energy ranges and at clinical flux rates in MedAustron IR1

The Medipix3, a hybrid pixel detector with a silicon sensor, has been evaluated as a beam instrumentation device with proton and carbon ion measurements in the non-clinical research room (IR1) of MedAustron Ion Therapy Center. Protons energies are varied from 62.4 to 800 MeV with 104 to 108 protons per second impinging on the detector surface. For carbon ions, energies are varied from 120 to 400 MeV/amu with 107 to 108 carbon ions per second. Measurements include simultaneous high resolution, beam profile and beam intensity with various beam parameters at up to 1000 FPS (frames per second), count rate linearity and an assessment of radiation damage after the measurement day using an x-ray tube to provide a homogeneous radiation measurement. The count rate linearity is found to be linear within the uncertainties (dominated by accelerator related sources due to special setup) for the measurements without degraders. Various frequency components are identified within the beam intensity over time firstly including 49.98 Hz with standard deviation, σ = 0.29, secondly 30.55 Hz σ = 0.55 and thirdly 252.51 Hz σ = 0.83. A direct correlation between the number of zero counting and noisy pixels is observed in the measurements with the highest flux. No conclusive evidence of long term radiation damage was found as a result of these measurements over one day.

Intra- and inter-fraction relative range verification in heavy-ion therapy using filtered interaction vertex imaging

Heavy-ion therapy, particularly using scanned (active) beam delivery, provides a precise and highly conformal dose distribution, with maximum dose deposition for each pencil beam at its endpoint (Bragg peak), and low entrance and exit dose. To take full advantage of this precision, robust range verification methods are required; these methods ensure that the Bragg peak is positioned correctly in the patient and the dose is delivered as prescribed. Relative range verification allows intra-fraction monitoring of Bragg peak spacing to ensure full coverage with each fraction, as well as inter-fraction monitoring to ensure all fractions are delivered consistently. To validate the proposed filtered Interaction Vertex Imaging method for relative range verification, a 16O beam was used to deliver 12 Bragg peak positions in a 40 mm poly-(methyl methacrylate) phantom. Secondary particles produced in the phantom were monitored using position-sensitive silicon detectors. Events recorded on these detectors, along with a measurement of the treatment beam axis, were used to reconstruct the sites of origin of these secondary particles in the phantom. The distal edge of the depth distribution of these reconstructed points was determined with logistic fits, and the translation in depth required to minimize the χ2 statistic between these fits was used to compute the range shift between any two Bragg peak positions. In all cases, the range shift was determined with sub-millimeter precision, to a standard deviation of the mean of 220(10) μm. This result validates filtered Interaction Vertex Imaging as a reliable relative range verification method, which should be capable of monitoring each energy step in each fraction of a scanned heavy-ion treatment plan.

Evidence Mapping of Proton Therapy, Heavy Ion Therapy, and Helical Tomotherapy for Gastric Cancer

<b><i>Purpose:</i></b> This study aimed to systematically present application situation and therapeutic effect of proton therapy (PT), heavy ion therapy, and helical tomotherapy (TOMO) for gastric cancer (GC), and to find gaps of existing studies. <b><i>Methods:</i></b> PubMed, EMBASE, the Cochrane Library, Web of Science, and Chinese Biological Medical Database were searched. Tables, bubble plot, and heat map were conducted to display results. <b><i>Results:</i></b> Fourteen studies were included. About PT, 7 single-arm studies showed median overall survival (OS) within 2–66 months and 1 study reported 40% of patients happened moderate degree of radiation gastritis. About TOMO, 1 study reported longer median OS and progression-free survival, lower occurrence of Grade III toxicity, and late toxicity compared to 3D-CRT, while another study remained neutral. About heavy ion therapy, there was no clinical study was found. <b><i>Conclusions:</i></b> Existing studies presented good clinic treatment effect about PT and TOMO for GC, and furthermore clinical studies are needed.

Hadrontherapy for Thymic Epithelial Tumors: Implementation in Clinical Practice

Radiation therapy is part of recommendations in the adjuvant settings for advanced stage or as exclusive treatment in unresectable thymic epithelial tumors (TETs). However, first-generation techniques delivered substantial radiation doses to critical organs at risk (OARs), such as the heart or the lungs, resulting in noticeable radiation-induced toxicity. Treatment techniques have significantly evolved for TET irradiation, and modern techniques efficiently spare normal surrounding tissues without negative impact on tumor coverage and consequently local control or patient survival. Considering its dosimetric advantages, hadrontherapy (which includes proton therapy and carbon ion therapy) has proved to be worthwhile for TET irradiation in particular for challenging clinical situations such as cardiac tumoral involvement. However, clinical experience for hadrontherapy is still limited and mainly relies on small-size proton therapy studies. This critical review aims to analyze the current status of hadrontherapy for TET irradiation to implement it at a larger scale.

Patient Attitudes About Light Therapy and Negative Ion Therapy for Nonseasonal Depression: An Online Survey Study

ABSTRACTObjectiveNo studies have yet evaluated whether light therapy or negative ion therapy can be used as maintenance treatment after acute treatment with antidepressants in patients with major depressive disorder. To address the importance of this question, we surveyed participants with depression to determine their knowledge and attitudes about light therapy and negative ion therapy, and their willingness to participate in a randomized clinical trial with these therapies substituting for antidepressants for maintenance treatment.MethodsParticipants with a self-reported diagnosis of depression were recruited by email, newsletters, and social media to complete an online survey with questions about awareness and effectiveness of light therapy and negative ion therapy for depression. Vignettes describing the use of these therapies for maintenance treatment were presented with follow up questions about the ease of use and reasons for wanting (and not wanting) to use the therapies instead of antidepressants. Another vignette described a randomized study with these therapies followed by questions on whether participants would likely volunteer for the study. Chi-square tests were used to examine differences in responses between therapies.ResultsA total of 221 participants completed the survey. Most of them were aware of both therapies, but more participants had heard of light therapy (95% compared to 62% for negative ion therapy, p<0.0001), had used light therapy (28% versus 16%, p<0.003), and regarded light therapy as effective (54% versus 37%, p<0.001). Both therapies were considered easy to use. The majority of participants (78%) thought that it was important to find non-medication therapies for maintenance treatment, and 77% responded that they would likely volunteer for a randomized study to determine efficacy of the two therapies for maintenance treatment.ConclusionPeople with depression are generally aware of light therapy and negative ion therapy and believe they would be good therapies to substitute for antidepressants in maintenance treatment. These findings support the importance and feasibility for a randomized relapse prevention trial with light therapy and negative ion therapy in patients with depression.