Systematizing the risk management process in clinical radiotherapy practice: Recommendations of the working group on risk management of the DGMP
The Deutsche Gesellschaft für Medizinische Physik [German Society of Medical Physics] has recently published two coherent reports, No. 25 and No. 28, detailing the design and implementation of a risk management (RM) process for German radiotherapy (RT) departments. This study offers an overview and background of the efforts behind these reports.
Monte Carlo calculations of target fragments from helium and carbon ion interactions with water
When high energetic heavy ions interact with any target, short range, high linear energy transfer (LET) target fragments are produced. These target fragments (TFs) can give a significant dose to the healthy tissue during heavy ion cancer therapy, and when cosmic radiation interacts with astronauts. This paper presents Monte Carlo simulations, using the Particle and Heavy Ion Transport code System (PHITS), to characterize target fragments from reactions of helium and carbon ions with water. The calculated ranges, LET, doses, and production cross sections are presented. It is shown that protons, deuterons, tritons, alpha particles, He, He, nitrogen, oxygen, and fluorine ions are the most probable target fragments when carbon and helium ions collide with water. Among the produced target fragments, alpha particles and nitrogen ions give the highest dose to the targets, since the combination of fluence and LETs of these TFs are highest among the produced fragments. The production cross sections of proton and oxygen are the highest among the target fragments cross sections when helium and carbon ions imping on water, because these TFs can be produced through more reaction channels compared to other fragments. These findings are helpful for accurate dose measurement during heavy ion cancer therapy and for shielding of space radiation.
Large-field irradiation techniques in Germany: A DGMP Working Group survey on the current clinical implementation of total body irradiation, total skin irradiation and craniospinal irradiation
In 2023, a Germany-wide survey on the current clinical practice of three different large field irradiation techniques (LFIT), namely total body irradiation (TBI), total skin irradiation (TSI) and craniospinal irradiation (CSI), was conducted covering different aspects of the irradiation process, e.g., the irradiation unit and technique, dosimetrical aspects and treatment planning as well as quality assurance. The responses provided a deep insight into the applied approaches showing a high heterogeneity between participating centers for all three large field irradiation techniques. The highest heterogeneity was found for TBI. Here, differences between centers were found in almost every aspect of the irradiation process, e.g., the irradiation technique, the prescription dose, the spared organs at risk and the applied treatment planning method. For TBI, the only agreement was found in the fractionation scheme (2 Gy/fraction, 2 fractions/day) and the dose reduction to the lung. TSI was the rarest of the three LFITs. For TSI, the only agreement was found in the use of 6 MeV when irradiating with electrons. The reported approaches of CSI were closest to standard radiotherapy, using no CSI-specific irradiation techniques or treatment planning methods. For CSI, the only agreement was found in the prescribed dose to the brain (50 - 60 Gy). When asking for future requirements, participating centers considered the lack of standardization as the most important future challenge and suggested to perform (retrospective) patient studies. The results of such studies can then serve as a basis for new and improved guidelines.
Erratum to "Can Generative Adversarial Networks help to overcome the limited data problem in segmentation?" [Z Med Phys 32 (2022) 361-368]
Erratum to "Investigation of biases in convolutional neural networks for semantic segmentation using performance sensitivity analysis" [Z Med Phys 32 (2022) 346-360]
Erratum to "The role of Monte Carlo simulation in understanding the performance of proton computed tomography" [Z Med Phys 32 (2022) 23-38]
Erratum to "Automated parameter selection for accelerated MRI reconstruction via low-rank modeling of local k-space neighborhoods" [Z Med. Phys. 33 (2023) 203-219]
Erratum to "Commissioning and quality assurance of a novel solution for respiratory-gated PBS proton therapy based on optical tracking of surface markers" [Z Med Phys 32 (2022) 52-62]
Erratum to "Volumetric Na single and triple-quantum imaging at 7T: 3D-CRISTINA" [Z Med Phys 32 (2022) 199-208]
Erratum to "Free-breathing half-radial dual-echo balanced steady-state free precession thoracic imaging with wobbling Archimedean spiral pole trajectories" [Z Med. Phys. 33 (2023) 220-229]
Erratum to "Evaluation of an anthropomorphic ion chamber and 3D gel dosimetry head phantom at a 0.35 T MR-linac using separate 1.5 T MR-scanners for gel readout" [Z Med. Phys. 32 (2022) 312-325]
Influence of skin flap thickness on the transmission characteristics of middle ear implant audio processors
To measure signal transmission characteristics for audio processors of an active middle ear implant as a function of skin flap thickness, i.e., distance between audio processor and the implant's receiver coil.
An automated pipeline for computation and analysis of functional ventilation and perfusion lung MRI with matrix pencil decomposition: TrueLung
To introduce and evaluate TrueLung, an automated pipeline for computation and analysis of free-breathing and contrast-agent free pulmonary functional magnetic resonance imaging.
Erratum to "Multiple direction needle-path planning and inverse dose optimization for robotic low-dose rate brachytherapy" [Z Med Phys 32 (2022) 173-187]
Erratum to "A novel multipurpose device for guided knee motion and loading during dynamic magnetic resonance imaging" [Z Med Phys 32 (2022) 500-513]
Re-evaluation of the prospective risk analysis for artificial-intelligence driven cone beam computed tomography-based online adaptive radiotherapy after one year of clinical experience
Cone-beam computed tomography (CBCT)-based online adaptation is increasingly being introduced into many clinics. Upon implementation of a new treatment technique, a prospective risk analysis is required and enhances workflow safety. We conducted a risk analysis using Failure Mode and Effects Analysis (FMEA) upon the introduction of an online adaptive treatment programme (Wegener et al., Z Med Phys. 2022). A prospective risk analysis, lacking in-depth clinical experience with a treatment modality or treatment machine, relies on imagination and estimates of the occurrence of different failure modes. Therefore, we systematically documented all irregularities during the first year of online adaptation, namely all cases in which quality assurance detected undesired states potentially leading to negative consequences. Additionally, the quality of automatic contouring was evaluated. Based on those quantitative data, the risk analysis was updated by an interprofessional team. Furthermore, a hypothetical radiation therapist-only workflow during adaptive sessions was included in the prospective analysis, as opposed to the involvement of an interprofessional team performing each adaptive treatment. A total of 126 irregularities were recorded during the first year. During that time period, many of the previously anticipated failure modes (almost) occurred, indicating that the initial prospective risk analysis captured relevant failure modes. However, some scenarios were not anticipated, emphasizing the limits of a prospective risk analysis. This underscores the need for regular updates to the risk analysis. The most critical failure modes are presented together with possible mitigation strategies. It was further noted that almost half of the reported irregularities applied to the non-adaptive treatments on this treatment machine, primarily due to a manual plan import step implemented in the institution's workflow.
Reducing electromagnetic interference in MR thermometry: A comparison of setup configurations for MR-guided microwave ablations
Magnetic Resonance (MR) thermometry is used for the monitoring of MR-guided microwave ablations (MWA), and for the intraoperative evaluation of ablation regions. Nevertheless, the accuracy of temperature mapping may be compromised by electromagnetic interference emanating from the microwave (MW) generator. This study evaluated different setups for improving magnetic resonance imaging (MRI) during MWA with a modified MW generator. MWA was performed in 15 gel phantoms comparing three setups: The MW generator was placed outside the MR scanner room, either connected to the MW applicator using a penetration panel with a radiofrequency (RF) filter and a 7 m coaxial cable (Setup 1), or through a waveguide using a 5 m coaxial cable (Setup 2). Setup 3 employed the MW generator within the MR scan room, connected by a 5 m coaxial cable. The coaxial cables in setups 2 and 3 were modified with custom shielding to reduce interference. The setups during ablation (active setup) were compared to a reference setup without the presence of the MW system. Thermometry and thermal dose maps (CEM43 model) were compared for the three configurations. Primary endpoints for assessment were signal-to-noise ratio (SNR), temperature precision, Sørensen-Dice-Coefficient (DSC), and RF-noise spectra. Setup 3 showed highly significant electromagnetic interference during ablation with a SNR decrease by -60.4%±13.5% (p<0.001) compared to reference imaging. For setup 1 and setup 2 no significant decrease in SNR was measured with differences of -2.9%±9.8% (p=0.6) and -1.5%±12.8% (p=0.8), respectively. SNR differences were significant between active setups 1 and 3 with -51.2%±16.1% (p<0.001) and between active setups 2 and 3 with -59.0%±15.5% (p<0.001) but not significant between active setups 1 and 2 with 19.0%±13.7% (p=0.09). Furthermore, no significant differences were seen in temperature precision or DSCs between all setups, ranging from 0.33 °C ± 0.04 °C (Setup 1) to 0.38 °C ± 0.06 °C (Setup 3) (p=0.6) and from 87.0%±1.6% (Setup 3) to 88.1%±1.6% (Setup 2) (p=0.58), respectively. Both setups (1 and 2) with the MW generator outside the MR scanner room were beneficial to reduce electromagnetic interference during MWA. Moreover, provided that a shielded cable is utilized in setups 2 and 3, all configurations displayed negligible differences in temperature precision and DSCs, indicating that the location of the MW generator does not significantly impact the accuracy of thermometry during MWA.
Erratum to "Tumour volume distribution can yield information on tumour growth and tumour control" [Z Med Phys 32 (2022) 143-148]
Non-contrast free-breathing liver perfusion imaging using velocity selective ASL combined with prospective motion compensation
To apply velocity selective arterial spin labeling (VSASL) combined with a navigator-based (NAV) prospective motion compensation method for a free-breathing liver perfusion measurement without contrast agent.