Seismic risk mitigation at Campi Flegrei in volcanic unrest.

Campi Flegrei is a densely populated volcanic area in Italy. Its inner caldera periodically experiences uplift and subsidence, known as bradyseism, also accompanied by seismic activity. In the last decade, with uplift rates up to 2 cm/month, about nine-thousand earthquakes were recorded.

Inter- and intrafractional 4D dose accumulation for evaluating ΔNTCP robustness in lung cancer.

Background And Purpose: Model-based selection of proton therapy patients relies on a predefined reduction in normal tissue complication probability (NTCP) with respect to photon therapy. The decision is necessarily made based on the treatment plan, but NTCP can be affected when the delivered treatment deviates from the plan due to delivery inaccuracies. Especially for proton therapy of lung cancer, this can be important because of tissue density changes and, with pencil beam scanning, the interplay effect between the proton beam and breathing motion.

Commissioning of a clinical pencil beam scanning proton therapy unit for ultra-high dose rates (FLASH).

Purpose: The purpose of this work was to provide a flexible platform for FLASH research with protons by adapting a former clinical pencil beam scanning gantry to irradiations with ultra-high dose rates.

Methods: PSI Gantry 1 treated patients until December 2018. We optimized the beamline parameters to transport the 250 MeV beam extracted from the PSI COMET accelerator to the treatment room, maximizing the transmission of beam intensity to the sample.

Clinical outcomes of head and neck adenoid cystic carcinoma patients treated with pencil beam-scanning proton therapy.

Objective: The aim of this study was to evaluate the outcome of patients with head and neck adenoid cystic carcinoma (ACC) treated using pencil beam scanning proton therapy (PBS PT) at our institution.

Materials And Methods: Thirty-five patients who underwent treatment with PBS PT for ACC between 2001 and 2017 were included. Local control (LC), distant control (DC), progression-free survival (PFS), overall survival (OS) and their prognostic factors were evaluated.

Can Technological Improvements Reduce the Cost of Proton Radiation Therapy?

In recent years there has been increasing interest in the more extensive application of proton therapy in a clinical and preferably hospital-based environment. However, broader adoption of proton therapy has been hindered by the costs of treatment, which are still much higher than those in advanced photon therapy. This article presents an overview of on-going technical developments, which have a reduction of the capital investment or operational costs either as a major goal or as a potential outcome.

Long-Term Clinical Safety of High-Dose Proton Radiation Therapy Delivered With Pencil Beam Scanning Technique for Extracranial Chordomas and Chondrosarcomas in Adult Patients: Clinical Evidence of Spinal Cord Tolerance.

Purpose: To assess the radiation dose tolerance of the spinal cord by reviewing our institutional experience regarding the incidence of radiation-induced spinal cord toxicity after high-dose pencil beam scanning proton therapy (PBSPT).

Methods And Materials: Seventy-six patients (median age 53 years; range, 23-79 years) treated for spinal chordoma (n=55) or chondrosarcoma (n=21) met the following criteria and were retrospectively analyzed: PBSPT only, no reirradiation or concomitant chemotherapy, maximum dose (Dmax) to the spinal cord of ≥45 Gy(relative biological effectiveness [RBE]), ≥18 years of age, and follow-up of ≥12 months. The delivered dose was 59.

An Analysis of Plan Robustness for Esophageal Tumors: Comparing Volumetric Modulated Arc Therapy Plans and Spot Scanning Proton Planning.

Purpose: Planning studies to compare x-ray and proton techniques and to select the most suitable technique for each patient have been hampered by the nonequivalence of several aspects of treatment planning and delivery. A fair comparison should compare similarly advanced delivery techniques from current clinical practice and also assess the robustness of each technique. The present study therefore compared volumetric modulated arc therapy (VMAT) and single-field optimization (SFO) spot scanning proton therapy plans created using a simultaneous integrated boost (SIB) for dose escalation in midesophageal cancer and analyzed the effect of setup and range uncertainties on these plans.

Differential DNA repair pathway choice in cancer cells after proton- and photon-irradiation.

Background And Purpose: Non-homologous end-joining (NHEJ) and homologous recombination (HR) contribute to the repair of irradiation-induced DNA double-strand breaks (DSBs). We investigated the impact of the two major DSB repair machineries for cellular survival of human tumor cells in response to proton- and photon-irradiation.

Materials And Methods: DNA damage repair and cell survival were analyzed in wildtype, HR- and NHEJ-repair-compromised and pharmacologically DNA-PKcs-inhibited human tumor cells in response to clinically relevant, low-linear energy transfer proton- and 200-keV photon-irradiation.

Characterizing a proton beam scanning system for Monte Carlo dose calculation in patients.

The presented work has two goals. First, to demonstrate the feasibility of accurately characterizing a proton radiation field at treatment head exit for Monte Carlo dose calculation of active scanning patient treatments. Second, to show that this characterization can be done based on measured depth dose curves and spot size alone, without consideration of the exact treatment head delivery system.

Variations in linear energy transfer within clinical proton therapy fields and the potential for biological treatment planning.

Purpose: To calculate the linear energy transfer (LET) distributions in patients undergoing proton therapy. These distributions can be used to identify areas of elevated or diminished biological effect. The location of such areas might be influenced in intensity-modulated proton therapy (IMPT) optimization.

Proton therapy for malignant pleural mesothelioma after extrapleural pleuropneumonectomy.

Purpose: To perform comparative planning for intensity-modulated radiotherapy (IMRT) and proton therapy (PT) for malignant pleural mesothelioma after radical surgery.

Methods And Materials: Eight patients treated with IMRT after extrapleural pleuropneumonectomy (EPP) were replanned for PT, comparing dose homogeneity, target volume coverage, and mean and maximal dose to organs at risk. Feasibility of PT was evaluated regarding the dose distribution with respect to air cavities after EPP.

Proton spot scanning radiotherapy of spontaneous canine tumors.

Thirty dogs with spontaneous tumors were irradiated with proton therapy using a novel spot scanning technique to evaluate the safety and efficacy of the system, and to study the acute and late radiation reactions. Nasal tumors, soft tissue sarcomas, and miscellaneous tumors of the head were treated with a median total dose of 52.5 Gy given in 3.

["Spot-scanning" proton therapy for rhabdomyosarcomas of early childhood. First experiences at PSI].

Purpose: To evaluate the feasibility and acute toxicity of spot-scanning proton therapy under deep sedation in young children with rhabdomyosarcomas (RMS).

Patients And Methods: Since 2004, children requiring sedation can be admitted for proton therapy at Paul Scherrer Institute (PSI), Villigen, Switzerland. Children under 5 years of age with RMS of the head and the trunk were analyzed.

Is the risk for secondary cancers after proton therapy enhanced distal to the Planning Target Volume? A two-case report with possible explanations.

It is often assumed that radiation-induced secondary cancer after proton therapy forms preferentially close to the distal fall-off of the spread-out Bragg peak because of an increased relative biological effectiveness (RBE) with regard to cancer induction of low-energy protons. In this study we analyze to what extent dose gradients distal to the Planning Target Volume (PTV) may, independently from the RBE, contribute to enhanced radiation carcinogenesis. The study is based on two dogs which, out of 30 dogs treated with proton therapy at the Paul Scherrer Institute (PSI), developed a secondary cancer.

Intensity modulation in radiotherapy: photons versus protons in the paranasal sinus.

Purpose: The purpose of this study is to investigate whether successive tightening of normal tissue constraints on an intensity modulated X-ray therapy plan might be able to improve it to the point of clinical comparability with the corresponding intensity modulated proton therapy plan.

Materials And Methods: Photon and proton intensity modulated plans were calculated for a paranasal sinus case using nominal dose constraints. Additional photon plans were then calculated in an effort to match the dose-volume histograms of the critical structures to those of the proton plan.