To investigate magnetic field effects on the dose distribution and ionization chambers response in carbon ion reference fields and determine magnetic field correction factors for chambers of different volumes.The response of six Farmer-type chambers with varying radii (1-6 mm, termed as R1-R6) was measured in magnetic fields up to 1 T in 0.1 T increments using an experimental electromagnet and compared with Monte Carlo simulations.
View Article and Find Full Text PDFInt J Comput Assist Radiol Surg
February 2025
Purpose: Complicated type B Aortic dissection is a severe aortic pathology that requires treatment through thoracic endovascular aortic repair (TEVAR). During TEVAR a stentgraft is deployed in the aortic lumen in order to restore blood flow. Due to the complicated pathology including an entry, a resulting dissection wall with potentially several re-entries, replicating this structure artificially has proven to be challenging thus far.
View Article and Find Full Text PDFBackground: Particle mini-beam therapy exhibits promise in sparing healthy tissue through spatial fractionation, particularly notable for heavy ions, further enhancing the already favorable differential biological effectiveness at both target and entrance regions. However, breathing-induced organ motion affects particle mini-beam irradiation schemes since the organ displacements exceed the mini-beam structure dimensions, decreasing the advantages of spatial fractionation.
Purpose: In this study, the impact of breathing-induced organ motion on the dose distribution was examined at the target and organs at risk(OARs) during carbon ion mini-beam irradiation for pancreatic cancer.
Int J Radiat Oncol Biol Phys
September 2024
Purpose: Our objective was to develop a methodology for assessing the linear energy transfer (LET) and relative biological effectiveness (RBE) in clinical proton and helium ion beams using fluorescent nuclear track detectors (FNTDs).
Methods And Materials: FNTDs were exposed behind solid water to proton and helium (He) ion spread-out Bragg peaks. Detectors were imaged with a confocal microscope, and the LET spectra were derived from the fluorescence intensity.
. Carbon ion radiotherapy is a promising radiation technique for malignancies like pancreatic cancer. However, organs' motion imposes challenges for achieving homogeneous dose delivery.
View Article and Find Full Text PDFBackground: Magnetic resonance-guided proton therapy is promising, as it combines high-contrast imaging of soft tissue with highly conformal dose delivery. However, proton dosimetry in magnetic fields using ionization chambers is challenging since the dose distribution as well as the detector response are perturbed.
Purpose: This work investigates the effect of the magnetic field on the ionization chamber response, and on the polarity and ion recombination correction factors, which are essential for the implementation of a proton beam dosimetry protocol in the presence of magnetic fields.
. Improvements in image-guided radiotherapy (IGRT) enable accurate and precise treatment of moving tumors in the abdomen while simultaneously sparing healthy tissue. However, the lack of validation tools for newly developed MR-guided radiotherapy hybrid devices such as the MR-Linac is an open issue.
View Article and Find Full Text PDFPurpose: Measurements comparing relative stopping power (RSP) accuracy of state-of-the-art systems representing single-energy and dual-energy computed tomography (SECT/DECT) with proton CT (pCT) and helium CT (HeCT) in biological tissue samples.
Methods: We used 16 porcine and bovine samples of various tissue types and water, covering an RSP range from 0.90 0.
This work provides a quantitative assessment of helium ion CT (HeCT) for particle therapy treatment planning. For the first time, HeCT based range prediction accuracy in a heterogeneous tissue phantom is presented and compared to single-energy x-ray CT (SECT), dual-energy x-ray CT (DECT) and proton CT (pCT). HeCT and pCT scans were acquired using the US pCT collaboration prototype particle CT scanner at the Heidelberg Ion-Beam Therapy Center.
View Article and Find Full Text PDFBiomed Phys Eng Express
July 2021
Polymer gel (PG) dosimetry is a valuable tool to measure complex dose distributions in 3D with a high spatial resolution. However, due to complex protocols that need to be followed for in-house produced PGs and the high costs of commercially available gels, PG gels are only rarely applied in quality assurance procedures worldwide. In this work, we provide an introduction to perform highly standardized dosimetric PG experiments using PAGAT (PolyAcrylamide Gelatine gel fabricated at ATmospheric conditions) dosimetry gel.
View Article and Find Full Text PDFAnn Chir Plast Esthet
August 2021
Introduction: Multiple surgical revisions (exeresis and directed healing) of recurrent pilonidal cysts are sources of unstable scars. Chronic ulcerations often appear with or without authentic recidivism. A local fasciocutaneous perforating flap based on the parasacral arteries would bring healthy tissue and avoid the disadvantages of conventional techniques (musculo-cutaneous or random).
View Article and Find Full Text PDFQuality assurance in magnetic resonance (MR)-guided radiotherapy lacks anthropomorphic phantoms that represent tissue-equivalent imaging contrast in both computed tomography (CT) and MR imaging. In this study, we developed phantom materials with individually adjustable CT value as well as [Formula: see text]- and [Formula: see text]-relaxation times in MR imaging at three different magnetic field strengths. Additionally, their experimental stopping power ratio (SPR) for carbon ions was compared with predictions based on single- and dual-energy CT.
View Article and Find Full Text PDFMR-integrated radiotherapy requires suitable dosimetry detectors to be used in magnetic fields. This study investigates the feasibility of using dedicated MR-compatible ionization chambers at MR-integrated radiotherapy devices. MR-compatible ionization chambers (Exradin A19MR, A1SLMR, A26MR, A28MR) were precisely modeled and their relative response in a 6MV treatment beam in the presence of a magnetic field was simulated using EGSnrc.
View Article and Find Full Text PDFObjective: To develop an anthropomorphic, deformable and multimodal pelvis phantom with positron emission tomography extension for radiotherapy (ADAM PETer).
Methods: The design of ADAM PETer was based on our previous pelvis phantom (ADAM) and extended for compatibility with PET and use in 3T magnetic resonance imaging (MRI). The formerly manually manufactured silicon organ surrogates were replaced by three-dimensional (3D) printed organ shells.
Introduction: The objective of this study is to highlight the factors that influence drain productivity in reduction mastoplasty.
Materials And Methods: We have retrospectively referenced from November 2015 to November 2017 all breast reduction performed in the plastic surgery, reconstructive and esthetic surgery department of the University Hospital of Nancy. A total of 222 breasts were analyzed by listing age, weight, height, Body Mass Index (BMI), smoking status, surgeon, technical used, hospitalization stay, breast volume removed, type and size of drain and their productivity.
Although improvements in medical treatment lead to a steadily rising survival rate of breast cancer patients (BCP), it is associated with a decrease in cognitive and affective function. The hippocampus, a brain region with a high influence on both cognitive and affective function, is increasingly becoming the focus of current research because of its high vulnerability to adverse direct (chemotherapeutic agents, endocrine therapeutic agents, and radiation) or indirect (stress and other psycho-social factors) treatment-related effects. This systematic review analyses current data from literature combining hippocampus-related brain changes due to breast cancer treatment with associated cancer-related cognitive and affective impairments (CRCI/CRAI).
View Article and Find Full Text PDFOnline adaptive treatment procedures in magnetic resonance (MR)-guided radiotherapy (MRgRT) allow compensating for inter-fractional anatomical variations in the patient. Clinical implementation of these procedures, however, requires specific end-to-end tests to validate the treatment chain including imaging, treatment planning, positioning, treatment plan adaption and accurate dose delivery. For this purpose, a new phantom with reproducibly adjustable anthropomorphic structures has been developed.
View Article and Find Full Text PDFFor hybrid devices combining magnetic resonance (MR) imaging and a linac for radiation treatment, the isocenter accuracy as well as image distortions have to be checked. This study presents a new phantom to investigate MR-Linacs in a single measurement in terms of (i) isocentricity of the irradiation and (ii) alignment of the irradiation and imaging isocenter relative to each other using polymer dosimetry gel as well as (iii) 3-dimensional (3D) geometric MR image distortions. The evaluation of the irradiated gel was performed immediately after irradiation with the imaging component of the 0.
View Article and Find Full Text PDFSubject: The objective of this study is to report our experience in the management of septic complications arising from pulmonary resection surgery by placing a pedicled upper back muscle flap associated with dressings by therapy. Negative pressure in all patients supported in our center from November 2015 to March 2018.
Material And Methods: Characteristics of fourteen patients with a pedicled dorsal muscle flap in the context of chronic empyema associated with bronchopulmonary fistula were identified.
Polymer gel (PG) dosimetry enables three dimensional (3D) measurement of complex dose distributions. However, PGs are strongly reactive with oxygen and other contaminations, limiting their applicability by the need to use specific container materials. We investigate different 3D printing materials and printing techniques for their compatibility with PG.
View Article and Find Full Text PDFPhys Med Biol
February 2019
Applicability and accuracy of the rapidly developing tools and workflows for image-guided radiotherapy need to be validated under realistic treatment-like conditions. We present the construction of the ADAM-pelvis phantom, an anthropomorphic, deformable and multimodal (CT and MRI) phantom of the male pelvis. The phantom covers patient-like uncertainties in image-guided radiotherapy workflows including imaging artifacts for the special case of the human anatomy as well as organ motion.
View Article and Find Full Text PDFFor conventional irradiation devices, the radiation isocenter accuracy is determined by star shot measurements on films. In magnetic resonance (MR)-guided radiotherapy devices, the results of this test may be altered by the magnetic field and the need to align the radiation and imaging isocenter may require a modification of measurement procedures. Polymer dosimetry gels (PG) may offer a way to perform both, the radiation and imaging isocenter test, however, first it has to be shown that PG reveal results comparable to the conventionally applied films.
View Article and Find Full Text PDFDebridement is a crucial component of wound management. Recent technologies such as hydrosurgery (Versajet), ultrasound therapy (the MIST therapy device), or plasma-mediated bipolar radio-frequency ablation therapy (Coblation) seem to represent interesting alternatives for wound debridement. The purpose of this systematic review was to describe, evaluate, and compare these three recently developed methods for the management of chronic wounds.
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