Zeitschrift fur Medizinische Physik最新文献

{"title":"Quantum physics at a historic milestone: How has it shaped medical physics?","authors":"Michael Bock , Jürgen R. Reichenbach","doi":"10.1016/j.zemedi.2025.02.002","DOIUrl":"10.1016/j.zemedi.2025.02.002","url":null,"abstract":"","PeriodicalId":54397,"journal":{"name":"Zeitschrift fur Medizinische Physik","volume":"35 2","pages":"Pages 123-126"},"PeriodicalIF":2.4,"publicationDate":"2025-05-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143574786","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"医学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Impact of log file source and data frequency on accuracy of log file-based patient specific quality assurance","authors":"Akbar Azzi ,&nbsp;Gerd Heilemann ,&nbsp;Dietmar Georg ,&nbsp;Supriyanto Ardjo Pawiro ,&nbsp;Terry Mart ,&nbsp;Wolfgang Lechner","doi":"10.1016/j.zemedi.2023.05.006","DOIUrl":"10.1016/j.zemedi.2023.05.006","url":null,"abstract":"<div><div>Performing phantom measurements for patient-specific quality assurance (PSQA) adds a significant amount of time to the adaptive radiotherapy procedure. Log file based PSQA can be used to increase the efficiency of this process. This study compared the dosimetric accuracy of high-frequency linear accelerator (Linac) log files and low-frequency log data stored in the oncology information system (OIS). Thirty patients were included, that were recently treated in the head and neck (HN), brain, and prostate region with volumetric modulated arc therapy (VMAT) and an additional ten patients treated using stereotactic body radiation therapy (SBRT) with 3D-conformal radiotherapy (3D-CRT) technique. Log data containing a single fraction were used to calculate the dose distributions. The dosimetric differences between Linac log files and OIS logs were evaluated with a gamma analysis with 2%/2 mm criterion and dose threshold of 30%. The original treatment plan was used as a reference. Moreover, DVH parameters of D_98%, D_50%, and D_2% of the planning-target volume (PTV) and dose to several organs at risk (OARs) were reported. Significant differences in dose distributions between the two log types and the original dose were observed for PTV D_98% and D_2% (r &lt; 0.001) for HN cases, PTV D_98% (r = 0.005) for brain cases, and PTV D_50% (<em>r</em> = 0.015) for prostate cases. No significant differences were found between the two log types with respect to D_50%. The root mean square (RMS) error of the leaf positions of the OIS log was approximately twice the RMS error of the Linac log file for VMAT plans, but identical for 3D-CRT plans. The relationship between the gamma pass rate and the RMS error showed a moderate correlation for the Linac log files (<em>r</em> = −0.58, <em>p</em> &lt; 0.001) and strong correlation for OIS logs (<em>r</em> = −0.71, <em>p</em> &lt; 0.001). Furthermore, all doses calculated using Linac log files and OIS log data had a GPR &gt;90% for an RMS error &lt; 3.3 mm. Based on these findings, a tolerance limit of RMS error of 3.3 mm for considering OIS log based PSQA was established. Nevertheless, the OIS log data quality should be improved to achieve adequate PSQA.</div></div>","PeriodicalId":54397,"journal":{"name":"Zeitschrift fur Medizinische Physik","volume":"35 2","pages":"Pages 152-160"},"PeriodicalIF":2.4,"publicationDate":"2025-05-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"9680256","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"医学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Physical wedge as a tool for radiochromic film calibration","authors":"Stevan Pecić ,&nbsp;Miloš Vićić ,&nbsp;Ivan Belča ,&nbsp;Strahinja Stojadinović ,&nbsp;Borko Nidžović ,&nbsp;Ljubomir Kurij ,&nbsp;Slobodan Dević","doi":"10.1016/j.zemedi.2023.05.008","DOIUrl":"10.1016/j.zemedi.2023.05.008","url":null,"abstract":"<div><div>Reliable calibration is one of the major challenges in using radiochromic films (RCF) for radiation dosimetry. In this study the feasibility of using dose gradients produced by a physical wedge (PW) for RCF calibration was investigated. The aim was to establish an efficient and reproducible method for calibrating RCF using a PW. Film strips were used to capture the wedge dose profile for five different exposures and the acquired scans were processed to generate corresponding net optical density wedge profiles. The proposed method was compared to the benchmark calibration, following the guidelines for precise calibration using uniform dose fields. The results of the benchmark comparison presented in this paper showed that using a single film strip for measuring wedge dose profile is sufficient for estimating a reliable calibration curve within the recorded dose range. Furthermore, the PW calibration can be extrapolated or extended by using multiple gradients for the optimal coverage of the desired calibration dose range. The method outlined in this paper can be readily replicated using the equipment and expertise commonly found in a radiotherapy center. Once the dose profile and central axis attenuation coefficient of the PW are determined, they can serve as a reference for a variety of calibrations using different types and batches of film. This investigation demonstrated that the calibration curves obtained with the presented PW calibration method are within the bounds of the measurement uncertainty evaluated for the conventional uniform dose field calibration method.</div></div>","PeriodicalId":54397,"journal":{"name":"Zeitschrift fur Medizinische Physik","volume":"35 2","pages":"Pages 161-168"},"PeriodicalIF":2.4,"publicationDate":"2025-05-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"9726494","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"医学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Comparison of different neurite density metrics with brain asymmetry evaluation","authors":"Ivan I. Maximov ,&nbsp;Lars T. Westlye","doi":"10.1016/j.zemedi.2023.07.003","DOIUrl":"10.1016/j.zemedi.2023.07.003","url":null,"abstract":"<div><div>The standard diffusion MRI model with intra- and extra-axonal water pools offers a set of microstructural parameters describing brain white matter architecture. However, non-linearities in the standard model and diffusion data contamination by noise and imaging artefacts make estimation of diffusion metrics challenging. In order to develop reliable diffusion approaches and to avoid computational model degeneracy, additional theoretical assumptions allowing stable numerical implementations are required. Advanced diffusion approaches allow for estimation of intra-axonal water fraction (AWF), describing a key structural characteristic of brain tissue. AWF can be interpreted as an indirect measure or proxy of neurite density and has a potential as useful clinical biomarker. Established diffusion approaches such as white matter tract integrity, neurite orientation dispersion and density imaging (NODDI), and spherical mean technique provide estimates of AWF within their respective theoretical frameworks. In the present study, we estimated AWF metrics using different diffusion approaches and compared measures of brain asymmetry between the different metrics in a sub-sample of 182 subjects from the UK Biobank. Multivariate decomposition by mean of linked independent component analysis revealed that the various AWF proxies derived from the different diffusion approaches reflect partly non-overlapping variance of independent components, with distinct anatomical distributions and sensitivity to age. Further, voxel-wise analysis revealed age-related differences in AWF-based brain asymmetry, indicating less apparent left-right hemisphere difference with higher age. Finally, we demonstrated that NODDI metrics suffer from a quite strong dependence on used numerical algorithms and post-processing pipeline. The analysis based on AWF metrics strongly depends on the used diffusion approach and leads to poorly reproducible results.</div></div>","PeriodicalId":54397,"journal":{"name":"Zeitschrift fur Medizinische Physik","volume":"35 2","pages":"Pages 177-192"},"PeriodicalIF":2.4,"publicationDate":"2025-05-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"9974632","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"医学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Gamma radiation detector selection for CT scanner","authors":"Kajal Kumari,&nbsp;Mayank Goswami","doi":"10.1016/j.zemedi.2023.07.006","DOIUrl":"10.1016/j.zemedi.2023.07.006","url":null,"abstract":"<div><div>Three types of gamma radiation detectors associated with distributed electronics namely, NaI (Tl), HPGe and <span><math><mrow><msub><mrow><mi>LaBr</mi></mrow><mn>3</mn></msub><mrow><mo>(</mo><mi>C</mi><mi>e</mi><mo>)</mo></mrow></mrow></math></span> are compared primarily focusing on electronic noise and scattering noise. Additionally, detectors of same make, material, size and electronics are also compared. A methodology is proposed to select the most suitable detector for computed tomography (CT) among the available options. Standard deviation parameter is employed to estimate electronic noise without performing CT experiment. Kanpur theorem-1(KT-1) is used to estimate the scattering noise quantitatively after verifying its sensitivity to scattering noise. The impact of scattering noise on CT profiles is evaluated using dice similarity dice coefficient. A good resemblance between KT-1 and dice coefficient is observed. A maximum difference of 56% in scattering noise is observed when five detectors used simultaneously instead of single detector whereas a discrepancy of 85% is observed between different types of radiation detectors. As far as ease of handling, operational and capital cost is concern one has to compromise minimum 12% of accuracy in CT reconstruction if NaI (Tl) detector is used with respect to best alternative available.</div><div>The proposed methodology can be applied to measurement that require minimal scattering interference data other than CT experiments. The manufacturer can add noise level of detector as a characteristic parameter in the data sheet.</div></div>","PeriodicalId":54397,"journal":{"name":"Zeitschrift fur Medizinische Physik","volume":"35 2","pages":"Pages 128-137"},"PeriodicalIF":2.4,"publicationDate":"2025-05-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"10016697","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"医学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Quality assurance and temporal stability of a 1.5 T MRI scanner for MR-guided Photon and Particle Therapy","authors":"Stefan Dorsch ,&nbsp;Katharina Paul ,&nbsp;Cedric Beyer ,&nbsp;Christian P Karger ,&nbsp;Oliver Jäkel ,&nbsp;Jürgen Debus ,&nbsp;Sebastian Klüter","doi":"10.1016/j.zemedi.2023.04.004","DOIUrl":"10.1016/j.zemedi.2023.04.004","url":null,"abstract":"<div><h3>Purpose</h3><div>To describe performance measurements, adaptations and time stability over 20 months of a diagnostic MR scanner for integration into MR-guided photon and particle radiotherapy.</div></div><div><h3>Material and methods</h3><div>For realization of MR-guided photon and particle therapy (MRgRT/MRgPT), a 1.5 T MR scanner was installed at the Heidelberg Ion Beam Therapy Center. To integrate MRI into the treatment process, a flat tabletop and dedicated coil holders for flex coils were used, which prevent deformation of the patient external contour and allow for the use of immobilization tools for reproducible positioning. The signal-to-noise ratio (SNR) was compared for the diagnostic and therapy-specific setup using the flat couch top and flexible coils for the a) head &amp; neck and b) abdominal region as well as for different bandwidths and clinical pulse sequences. Additionally, a quality assurance (QA) protocol with monthly measurements of the ACR phantom and measurement of geometric distortions for a large field-of-view (FOV) was implemented to assess the imaging quality parameters of the device over the course of 20 months.</div></div><div><h3>Results</h3><div>The SNR measurements showed a decreased SNR for the RT-specific as compared to the diagnostic setup of (a) 26% to 34% and (b) 11% to 33%. No significant bandwidth dependency for this ratio was found. The longitudinal assessment of the image quality parameters with the ACR and distortion phantom confirmed the long-term stability of the MRI device.</div></div><div><h3>Conclusion</h3><div>A diagnostic MRI was commissioned for use in MR-guided particle therapy. Using a radiotherapy specific setup, a high geometric accuracy and signal homogeneity was obtained after some adaptions and the measured parameters were shown to be stable over a period of 20 months.</div></div>","PeriodicalId":54397,"journal":{"name":"Zeitschrift fur Medizinische Physik","volume":"35 2","pages":"Pages 204-217"},"PeriodicalIF":2.4,"publicationDate":"2025-05-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"9480351","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"医学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Editorial Board + Consulting Editorial Board","authors":"","doi":"10.1016/S0939-3889(25)00044-3","DOIUrl":"10.1016/S0939-3889(25)00044-3","url":null,"abstract":"","PeriodicalId":54397,"journal":{"name":"Zeitschrift fur Medizinische Physik","volume":"35 2","pages":"Page iii"},"PeriodicalIF":2.4,"publicationDate":"2025-05-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144124767","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"医学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Silicone phantoms fabricated with multi-material extrusion 3D printing technology mimicking imaging properties of soft tissues in CT","authors":"Sepideh Hatamikia ,&nbsp;Laszlo Jaksa ,&nbsp;Gernot Kronreif ,&nbsp;Wolfgang Birkfellner ,&nbsp;Joachim Kettenbach ,&nbsp;Martin Buschmann ,&nbsp;Andrea Lorenz","doi":"10.1016/j.zemedi.2023.05.007","DOIUrl":"10.1016/j.zemedi.2023.05.007","url":null,"abstract":"<div><div>Recently, 3D printing has been widely used to fabricate medical imaging phantoms. So far, various rigid 3D printable materials have been investigated for their radiological properties and efficiency in imaging phantom fabrication. However, flexible, soft tissue materials are also needed for imaging phantoms for simulating several clinical scenarios where anatomical deformations is important. Recently, various additive manufacturing technologies have been used to produce anatomical models based on extrusion techniques that allow the fabrication of soft tissue materials. To date, there is no systematic study in the literature investigating the radiological properties of silicone rubber materials/fluids for imaging phantoms fabricated directly by extrusion using 3D printing techniques. The aim of this study was to investigate the radiological properties of 3D printed phantoms made of silicone in CT imaging. To achieve this goal, the radiodensity as described as Hounsfield Units (HUs) of several samples composed of three different silicone printing materials were evaluated by changing the infill density to adjust their radiological properties. A comparison of HU values with a Gammex Tissue Characterization Phantom was performed. In addition, a reproducibility analysis was performed by creating several replicas for specific infill densities. A scaled down anatomical model derived from an abdominal CT was also fabricated and the resulting HU values were evaluated. For the three different silicone materials, a spectrum ranging from −639 to +780 HU was obtained on CT at a scan setting of 120 kVp. In addition, using different infill densities, the printed materials were able to achieve a similar radiodensity range as obtained in different tissue-equivalent inserts in the Gammex phantom (238 HU to −673 HU). The reproducibility results showed good agreement between the HU values of the replicas compared to the original samples, confirming the reproducibility of the printed materials. A good agreement was observed between the HU target values in abdominal CT and the HU values of the 3D-printed anatomical phantom in all tissues.</div></div>","PeriodicalId":54397,"journal":{"name":"Zeitschrift fur Medizinische Physik","volume":"35 2","pages":"Pages 138-151"},"PeriodicalIF":2.4,"publicationDate":"2025-05-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"9695484","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"医学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"A modular system of flexible receive-only coil arrays for 3 T Magnetic Resonance Imaging","authors":"Lena Nohava,&nbsp;Michael Obermann,&nbsp;Roberta Frass-Kriegl,&nbsp;Onisim Soanca,&nbsp;Elmar Laistler","doi":"10.1016/j.zemedi.2023.05.002","DOIUrl":"10.1016/j.zemedi.2023.05.002","url":null,"abstract":"<div><div>Flexible form-fitting radiofrequency coils provide high signal-to-noise ratio (SNR) for magnetic resonance imaging (MRI), and in array configuration large anatomical areas of interest can be covered. We propose a modular system - “ModFlex”- of flexible lightweight 4-channel coaxial coil arrays for 3 T MRI. We investigated the performance difference between commercial reference coils and 8- and 16-channel ModFlex receive-only array systems. In vivo, six anatomical targets in four regions of interest – the neck, the ankle, the spine and the hip – were imaged with the novel coil array system. The versatility of ModFlex and the robustness of the coil characteristics for different use cases is demonstrated. We measured an SNR gain for 4 out of 6 and similar SNR for 2 out of 6 anatomical target regions as compared to commercial reference coils. Parallel imaging capabilities are comparable to standard coils in hip and neck imaging, but ModFlex outperforms standard coils in ankle and spine imaging. High SNR combined with high acceleration possibilities enables faster imaging workflows and/or high-resolution MR acquisitions. The coil’s versatility is beneficial for use cases with varying subject sizes and could improve patient comfort.</div></div>","PeriodicalId":54397,"journal":{"name":"Zeitschrift fur Medizinische Physik","volume":"35 2","pages":"Pages 193-203"},"PeriodicalIF":2.4,"publicationDate":"2025-05-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"9545731","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"医学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Characterization of a new radiochromic film (LD-V1) using mammographic beam qualities","authors":"Erika Nakajima,&nbsp;Hitoshi Sato","doi":"10.1016/j.zemedi.2023.05.004","DOIUrl":"10.1016/j.zemedi.2023.05.004","url":null,"abstract":"<div><h3>Purpose</h3><div>Radiochromic film (RCF) is a detector that can obtain a two-dimensional dose distribution with high resolution; it is widely used in medical and industrial fields. Several types of RCFs exist based on their application. The type of RCF mainly used for mammography dose assessment has been discontinued; however, a new type of RCF (LD-V1) has been distributed as a successor. Since the medical use of LD-V1 has rarely been studied, we investigated the response characteristics of LD-V1 in mammography.</div></div><div><h3>Methods</h3><div>Measurements were performed using Mo/Mo and Rh/Ag on a Senographe Pristina mammography device (GE, Fairfield, CT, USA). The reference air kerma was measured using a parallel-plate ionization chamber (PPIC) (C-MA, Applied Engineering Inc, Tokyo, Japan). Pieces of LD-V1 film model were irradiated at the same position where the reference air kerma in air was measured by the PPIC. Irradiation was performed using the time scale method based on the load on the equipment. Two methods of irradiation were considered: placing the detector in air and on the phantom. The LD-V1 was scanned five times at 72 dpi in RGB (48 bit) mode using a flatbed scanner (ES-G11000, Seiko Epson Corp, Nagano, Japan) 24 h following irradiation. The response ratio of the reference air kerma and the air kerma obtained from the LD-V1 were compared and examined for each beam quality and air kerma range.</div></div><div><h3>Results and discussion</h3><div>When the beam quality was altered, the response ratio varied from 0.8 to 1.2 with respect to the measurement value of the PPIC; however, some outliers were observed. Response ratios were highly variable in the low-dose range; however, as the air kerma increased, the ratios approached 1. Thus, LD-V1 does not need calibration for each beam quality used in mammography. LD-V1 enables air kerma evaluation by creating air kerma response curves under certain X-ray conditions used in mammography.</div></div><div><h3>Conclusion</h3><div>We suggest that the dose range be limited to 12 mGy or more to keep the response variation with beam qualities below ±20%. If further measurement is required for reducing the response variation, the dose range should be shifted to a higher dose range.</div></div>","PeriodicalId":54397,"journal":{"name":"Zeitschrift fur Medizinische Physik","volume":"35 2","pages":"Pages 169-176"},"PeriodicalIF":2.4,"publicationDate":"2025-05-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"9680258","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"医学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}