Medical physics最新文献

{"title":"Technical performance of dual-contrast-agent K-edge imaging with four energy thresholds on a commercial photon counting detector CT.","authors":"Kevin J Treb, Jeffrey F Marsh, Elisabeth R Shanblatt, Tristan Nowak, Chelsea A S Dunning, George S K Fung, Bernhard T Schmidt, Cynthia H McCollough, Shuai Leng","doi":"10.1002/mp.70063","DOIUrl":"https://doi.org/10.1002/mp.70063","url":null,"abstract":"<p><strong>Background: </strong>Photon counting detector CT (PCD-CT) has the potential to sort detected x-ray photons into more than two energy bins to perform multi-material decomposition using K-edge materials without additional mathematical constraints/assumptions. The availability of multiple energy thresholds in PCD-CT opens the possibility for unique clinical applications such as simultaneous multi-contrast-agent imaging.</p><p><strong>Purpose: </strong>To evaluate the technical performance of a PCD-CT system with four energy thresholds for conducting multi-material decomposition of iodine, gadolinium, and water after a comprehensive system calibration procedure.</p><p><strong>Methods: </strong>Experiments were performed on a commercial PCD-CT scanner (NAEOTOM Alpha, Siemens Healthineers) using a research mode with four energy thresholds. Material calibration was performed by scanning contrast materials with known concentration placed in various sizes of cylindrical water-equivalent phantoms at various tube currents and positions. From these data, per-voxel contrast models were derived for each material by multiple linear regressions up to second order, where the predictor variables were combinations of tube current, phantom diameter, and distance to isocenter. After calibration, small (20 cm diameter) and large (30 cm × 40 cm) uniform multi-energy CT phantoms and an anthropomorphic thorax phantom (31 cm × 39 cm), each containing bone, soft tissue, and several quantitative inserts of iodine (0.2-5.0 mg/ml), gadolinium (0.3-5.0 mg/ml), and a mixture of both (5.0 mg/ml each) were scanned using the four-energy threshold mode at 140 kV with energy thresholds set at 20, 52, 75, and 82 keV. Images for each energy threshold were reconstructed with a filtered back-projection algorithm and a quantitative kernel (Qr44). Subsequent image-based material decomposition was performed on individual voxels of the energy threshold images using the models derived from the calibration process to generate water, iodine, and gadolinium basis images. Quantitative material concentrations and image noise magnitudes, and noise power spectra (NPS) were measured.</p><p><strong>Results: </strong>Iodine and gadolinium concentrations above 1.25 mg/ml were visible in the material basis images in all phantoms. Averaged quantitative accuracy for iodine and gadolinium in the small, large, and thorax phantoms were 0.39 ± 0.30 mg/ml, 0.96 ± 0.53 mg/ml, and 0.53 ± 0.35 mg/ml, respectively. In the water basis images, accuracy was within 24 HU in all phantoms. Noise magnitudes in iodine and gadolinium basis images were 2.91 and 3.52 times that of the lowest energy threshold image for the small phantom, and were 6.92 and 7.17 times that of the lowest threshold image for the large phantom. Noise texture did not change between the energy threshold and material basis images for either size phantom as measured by the NPS.</p><p><strong>Conclusions: </strong>After a comprehensive syste","PeriodicalId":94136,"journal":{"name":"Medical physics","volume":"52 10","pages":"e70063"},"PeriodicalIF":3.2,"publicationDate":"2025-10-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145245850","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Next-generation nonstop gated CBCT for respiratory gating lung radiotherapy: Scan time and imaging dose.","authors":"Xiuxiu He, Mitchell Yu, Sean Berry, Yiming Gao, Yabo Fu, Wendy Harris, Weixing Cai, Yusuf Erdi, Kevin Stiles, Dustin Lynch, Seng Boh Lim, Laura Cervino, Tianfang Li, Xiang Li, Jean Moran, Hao Zhang","doi":"10.1002/mp.70065","DOIUrl":"https://doi.org/10.1002/mp.70065","url":null,"abstract":"<p><strong>Background: </strong>Free-breathing gated CBCT (gCBCT) is commonly prescribed for lung cancer patients undergoing respiratory gating radiotherapy. Recently, the nonstop gated CBCT (ngCBCT) has been proposed to significantly reduce scanning time and imaging dose while preserving high image quality.</p><p><strong>Purpose: </strong>To implement the novel ngCBCT imaging technique on a C-arm linear accelerator (LINAC) and quantitatively compare its scan time and imaging dose with those of the current clinical gCBCT.</p><p><strong>Methods: </strong>ngCBCT was implemented via a customized XML file in the developer mode of a C-arm LINAC, while gCBCT was acquired in the clinical mode. Both techniques employed the same thorax imaging protocol (half fan, full trajectory). Scan times were calculated from the timestamps of acquired projection data. Imaging dose was characterized using the weighted Cone-Beam Dose Index (CBDI_w), measured with a standard CTDI body phantom and two pencil chambers placed centrally and peripherally. Respiratory motion was simulated using a CIRS motion platform with both Cos4 waveforms (3-6 s cycles) and seven clinical patient breathing traces. Gating duty cycles of 30%-60% were tested for Cos4 motion, while the same gating window was reproduced for each patient's breathing trace.</p><p><strong>Results: </strong>Scan times for gCBCT ranged from 1.8 to 5 min, influenced by the gating duty cycle, breathing period, and waveform periodicity. In contrast, ngCBCT consistently achieved scan times of approximately 1 min. The imaging dose (CBDIw) for ngCBCT was reduced to 26.7%-60.1% of that for gCBCT, closely matching the respective gating duty cycles.</p><p><strong>Conclusion: </strong>This study demonstrates that ngCBCT acquisition is feasible on C-arm LINAC and offers substantial improvements in scan time and dose reduction compared to current clinical gCBCT. This novel technique has the potential to enhance patient comfort and broaden access to respiratory gating radiotherapy.</p>","PeriodicalId":94136,"journal":{"name":"Medical physics","volume":"52 10","pages":"e70065"},"PeriodicalIF":3.2,"publicationDate":"2025-10-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145246151","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Correction to \"Impact of bowtie filter and detector collimation on multislice CT scatter profiles: A simulation study\".","authors":"","doi":"10.1002/mp.17978","DOIUrl":"https://doi.org/10.1002/mp.17978","url":null,"abstract":"","PeriodicalId":94136,"journal":{"name":"Medical physics","volume":"52 10","pages":"e17978"},"PeriodicalIF":3.2,"publicationDate":"2025-10-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145240661","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Three-dimensional noise characteristics of clinical photon counting detector CT.","authors":"Humberto Monsivais, Xinming Liu, Frank Dong, Megan C Jacobsen, John Rong, Corey T Jensen, Ke Li","doi":"10.1002/mp.70067","DOIUrl":"https://doi.org/10.1002/mp.70067","url":null,"abstract":"&lt;p&gt;&lt;strong&gt;Background: &lt;/strong&gt;Since the introduction of whole-body photon-counting detector CT (PCD-CT) into clinical practice, extensive physics assessments have been conducted to elucidate its image quality advantages over energy-integrating detector CT (EID-CT) and to support its clinical adoption. However, evaluations of its three-dimensional (3D) noise power spectrum (NPS), which simultaneously quantifies in-plane and through-plane noise texture and magnitude, remain limited.&lt;/p&gt;&lt;p&gt;&lt;strong&gt;Purpose: &lt;/strong&gt;To experimentally evaluate the 3D NPS of an NAEOTOM Alpha PCD-CT system and its dependence on scan mode, reconstruction image type, quantum iterative reconstruction (QIR) strength, mono-energy (keV) level, spiral pitch, and radiation dose.&lt;/p&gt;&lt;p&gt;&lt;strong&gt;Methods: &lt;/strong&gt;Repeated scans of a 20 cm water phantom and a 30 cm PMMA phantom were conducted under the clinical Standard mode, clinical Ultra-High-Resolution (UHR) mode, and an Expert Service mode. Reconstructed image types include T3D, virtual monoenergetic image (VMI), and T1 (a linear reconstruction of total-energy bin available via the Expert Service mode). Data were collected at seven dose levels (0.4-24 mGy) and four spiral pitch levels (0.35-1.5). T3D and VMI images were reconstructed with varying QIR strengths, and VMIs were reconstructed at energies ranging from 40 to 190 keV. The 3D NPS, &lt;math&gt; &lt;semantics&gt;&lt;mrow&gt;&lt;mi&gt;NP&lt;/mi&gt; &lt;msub&gt;&lt;mi&gt;S&lt;/mi&gt; &lt;mrow&gt;&lt;mn&gt;3&lt;/mn&gt; &lt;mi&gt;D&lt;/mi&gt;&lt;/mrow&gt; &lt;/msub&gt; &lt;mrow&gt;&lt;mo&gt;(&lt;/mo&gt; &lt;mrow&gt;&lt;msub&gt;&lt;mi&gt;k&lt;/mi&gt; &lt;mi&gt;x&lt;/mi&gt;&lt;/msub&gt; &lt;mo&gt;,&lt;/mo&gt; &lt;msub&gt;&lt;mi&gt;k&lt;/mi&gt; &lt;mi&gt;y&lt;/mi&gt;&lt;/msub&gt; &lt;mo&gt;,&lt;/mo&gt; &lt;msub&gt;&lt;mi&gt;k&lt;/mi&gt; &lt;mi&gt;z&lt;/mi&gt;&lt;/msub&gt; &lt;/mrow&gt; &lt;mo&gt;)&lt;/mo&gt;&lt;/mrow&gt; &lt;/mrow&gt; &lt;annotation&gt;${mathrm{NP}}{{mathrm{S}}_{3{mathrm{D}}}}( {{k_x},{k_y},{k_z}} )$&lt;/annotation&gt;&lt;/semantics&gt; &lt;/math&gt; , was calculated from each ensemble of 3D image volumes. Axial &lt;math&gt; &lt;semantics&gt;&lt;mrow&gt;&lt;mi&gt;NP&lt;/mi&gt; &lt;msub&gt;&lt;mi&gt;S&lt;/mi&gt; &lt;mrow&gt;&lt;mn&gt;2&lt;/mn&gt; &lt;mi&gt;D&lt;/mi&gt;&lt;/mrow&gt; &lt;/msub&gt; &lt;mrow&gt;&lt;mo&gt;(&lt;/mo&gt; &lt;msub&gt;&lt;mi&gt;k&lt;/mi&gt; &lt;mrow&gt;&lt;mi&gt;x&lt;/mi&gt; &lt;mi&gt;y&lt;/mi&gt;&lt;/mrow&gt; &lt;/msub&gt; &lt;mo&gt;)&lt;/mo&gt;&lt;/mrow&gt; &lt;/mrow&gt; &lt;annotation&gt;${mathrm{NP}}{{mathrm{S}}_{2{mathrm{D}}}}( {{k_{xy}}} )$&lt;/annotation&gt;&lt;/semantics&gt; &lt;/math&gt; ​ was obtained by integrating NPS&lt;sub&gt;3D&lt;/sub&gt; along &lt;math&gt; &lt;semantics&gt;&lt;msub&gt;&lt;mi&gt;k&lt;/mi&gt; &lt;mi&gt;z&lt;/mi&gt;&lt;/msub&gt; &lt;annotation&gt;${k_z}$&lt;/annotation&gt;&lt;/semantics&gt; &lt;/math&gt; , while &lt;math&gt; &lt;semantics&gt;&lt;mrow&gt;&lt;mi&gt;NP&lt;/mi&gt; &lt;msub&gt;&lt;mi&gt;S&lt;/mi&gt; &lt;mrow&gt;&lt;mn&gt;1&lt;/mn&gt; &lt;mi&gt;D&lt;/mi&gt;&lt;/mrow&gt; &lt;/msub&gt; &lt;mrow&gt;&lt;mo&gt;(&lt;/mo&gt; &lt;msub&gt;&lt;mi&gt;k&lt;/mi&gt; &lt;mi&gt;z&lt;/mi&gt;&lt;/msub&gt; &lt;mo&gt;)&lt;/mo&gt;&lt;/mrow&gt; &lt;/mrow&gt; &lt;annotation&gt;${mathrm{NP}}{{mathrm{S}}_{1{mathrm{D}}}}( {{k_z}} )$&lt;/annotation&gt;&lt;/semantics&gt; &lt;/math&gt; ​ was obtained by integrating NPS&lt;sub&gt;3D&lt;/sub&gt; over &lt;math&gt; &lt;semantics&gt;&lt;msub&gt;&lt;mi&gt;k&lt;/mi&gt; &lt;mi&gt;x&lt;/mi&gt;&lt;/msub&gt; &lt;annotation&gt;${k_x}$&lt;/annotation&gt;&lt;/semantics&gt; &lt;/math&gt; and &lt;math&gt; &lt;semantics&gt;&lt;msub&gt;&lt;mi&gt;k&lt;/mi&gt; &lt;mi&gt;y&lt;/mi&gt;&lt;/msub&gt; &lt;annotation&gt;${k_y}$&lt;/annotation&gt;&lt;/semantics&gt; &lt;/math&gt; .&lt;/p&gt;&lt;p&gt;&lt;strong&gt;Results: &lt;/strong&gt;&lt;math&gt; &lt;semantics&gt;&lt;mrow&gt;&lt;mi&gt;NP&lt;/mi&gt; &lt;msub&gt;&lt;mi&gt;S&lt;/mi&gt; &lt;mrow&gt;&lt;mn&gt;1&lt;/mn&gt; &lt;mi&gt;D&lt;/mi&gt;&lt;/mrow&gt; &lt;/msub&gt; &lt;mrow&gt;&lt;mo&gt;(&lt;/mo&gt; &lt;msub&gt;","PeriodicalId":94136,"journal":{"name":"Medical physics","volume":"52 10","pages":"e70067"},"PeriodicalIF":3.2,"publicationDate":"2025-10-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145245949","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Interpretable wavelet transformer-enhanced framework for unsupervised deformable image registration.","authors":"Xinhao Bai, Hongpeng Wang, Yanding Qin, Jianda Han, Ningbo Yu","doi":"10.1002/mp.70056","DOIUrl":"https://doi.org/10.1002/mp.70056","url":null,"abstract":"<p><strong>Background: </strong>Deformable image registration (DIR) underpins quantitative analysis in clinical image-based diagnosis and intervention. Nevertheless, prevailing techniques falter due to their inadequate capacity to encapsulate high-frequency multi-scale data. Additionally, they lack explicit constraints on the deformation learning process, leading to poor interpretability.</p><p><strong>Purpose: </strong>To address these challenges, we propose WaveMorph, a DIR framework enhanced by discrete wavelet Transformers.</p><p><strong>Methods: </strong>The WaveMorph framework is composed of wavelet-based modules, characterized by their explicitly interpretable mathematical formulations. Specifically, we designed the Discrete Wavelet Transformer (DWFormer) module for the encoder, which helps capture high-frequency multi-scale details and enables information-preserving feature encoding. We also devised the Inverse Wavelet Transform Up-sampling (IWTU) enhanced decoder, which accumulates high-frequency multi-scale information from the encoder for precise reconstruction of the displacement vector field using a coarse-to-fine approach.</p><p><strong>Results: </strong>Comparative and ablation experiments were conducted on publicly available datasets, including OASIS, IXI, LPBA40, and MMWHS. Compared to state-of-the-art (SOTA) methods such as TransMorph, TransMatch, and UTSRMorph, our proposed method demonstrated superior performance.</p><p><strong>Conclusions: </strong>The experimental results show that the wavelet transformer-based network is effective in deformable MRI registration due to its ability to capture multi-scale features and its strong interpretability.</p>","PeriodicalId":94136,"journal":{"name":"Medical physics","volume":"52 10","pages":"e70056"},"PeriodicalIF":3.2,"publicationDate":"2025-10-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145246092","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"User evaluation of detector performance in clinical photon-counting and energy-integrating CT scanners using DICOM images.","authors":"Ke Li, Xinming Liu, Megan C Jacobsen, John Rong, Corey T Jensen, Eric P Tamm, Frank Dong","doi":"10.1002/mp.70045","DOIUrl":"10.1002/mp.70045","url":null,"abstract":"<p><strong>Background: </strong>Clinical users have a critical need to routinely assess the performance of photon-counting detectors (PCDs) in PCD-CT scanners. Such assessments provide insights into detector characteristics, support protocol optimization, and inform decisions on future scanner acquisitions. Historically, this has been challenging due to limited access to raw detector data, which restricts direct evaluation of PCD performance.</p><p><strong>Purpose: </strong>To evaluate the zero-frequency detective quantum efficiency ( <math> <semantics><msub><mi>DQE</mi> <mn>0</mn></msub> <annotation>${rm DQE}_0$</annotation></semantics> </math> ) and detector deadtime of PCDs from an end-user perspective using reconstructed DICOM images.</p><p><strong>Methods: </strong>Detector performance was evaluated on two Siemens NAEOTOM Alpha PCD-CT scanners and one Siemens SOMATOM Force energy-integrating detector CT (EID-CT) scanner. Air-only scans were performed in service mode across a range of tube potentials (70-140 kV) and tube currents (4-1200 mA). DICOM images were reconstructed on the scanner using a linear algorithm with a soft-tissue kernel (Br44). The noise power spectrum (NPS) of the images was used to estimate the mean detector output counts. Mean input photon numbers were estimated based on beam quality and exposure measurements. For the PCD-CT systems, tube current-sweep experiments were used to generate image variance-mA curves, from which detector deadtime was estimated using a previously validated parametric model.</p><p><strong>Results: </strong>The EID and PCD demonstrated comparable <math> <semantics><msub><mi>DQE</mi> <mn>0</mn></msub> <annotation>${rm DQE}_0$</annotation></semantics> </math> values (EID: 72%-74%; PCD: 72%-77%). <math> <semantics><msub><mi>DQE</mi> <mn>0</mn></msub> <annotation>${rm DQE}_0$</annotation></semantics> </math> showed no significant dependence on tube potential. The estimated PCD deadtime ranged from 5.3 to 7.0 ns. Detector performance was consistent across both PCD-CT systems. Additionally, the ultra-high-resolution (UHR) and standard acquisition modes exhibited equivalent deadtime.</p><p><strong>Conclusions: </strong>The <math> <semantics><msub><mi>DQE</mi> <mn>0</mn></msub> <annotation>${rm DQE}_0$</annotation></semantics> </math> of the PCD-CT and EID-CT detectors are comparable, with performance primarily limited by geometric efficiency rather than sensor absorption efficiency. Under clinically relevant conditions, pileup-induced count losses in the evaluated PCD-CT scanners are minimal and appear to be effectively corrected by the manufacturer.</p>","PeriodicalId":94136,"journal":{"name":"Medical physics","volume":"52 10","pages":"e70045"},"PeriodicalIF":3.2,"publicationDate":"2025-10-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.ncbi.nlm.nih.gov/pmc/articles/PMC12497395/pdf/","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145234787","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Evaluation of a CdTe semiconductor-based gamma camera for real-time dose dosimetry in boron neutron capture therapy.","authors":"I-Huan Chiu, Takahito Osawa, Takehiro Sumita, Kazuhiko Ninomiya, Shin'ichiro Takeda, Tadayuki Takahashi","doi":"10.1002/mp.70062","DOIUrl":"https://doi.org/10.1002/mp.70062","url":null,"abstract":"&lt;p&gt;&lt;strong&gt;Background: &lt;/strong&gt;Boron neutron capture therapy (BNCT) is a cancer treatment that leverages the nuclear reaction between boron-10 ( &lt;math&gt; &lt;semantics&gt; &lt;mrow&gt;&lt;msup&gt;&lt;mrow&gt;&lt;/mrow&gt; &lt;mn&gt;10&lt;/mn&gt;&lt;/msup&gt; &lt;mi&gt;B&lt;/mi&gt;&lt;/mrow&gt; &lt;annotation&gt;$^{10}{rm B}$&lt;/annotation&gt;&lt;/semantics&gt; &lt;/math&gt; ) and thermal neutrons to generate high-energy &lt;math&gt;&lt;semantics&gt;&lt;mi&gt;α&lt;/mi&gt; &lt;annotation&gt;$alpha$&lt;/annotation&gt;&lt;/semantics&gt; &lt;/math&gt; particles and &lt;math&gt; &lt;semantics&gt; &lt;mrow&gt;&lt;msup&gt;&lt;mrow&gt;&lt;/mrow&gt; &lt;mn&gt;7&lt;/mn&gt;&lt;/msup&gt; &lt;mi&gt;Li&lt;/mi&gt;&lt;/mrow&gt; &lt;annotation&gt;$^{7}{rm Li}$&lt;/annotation&gt;&lt;/semantics&gt; &lt;/math&gt; nuclei that selectively destroy cancer cells while sparing healthy tissues. However, BNCT is limited by current dosimetry methods that are incapable of monitoring boron distribution during therapy. An imaging system capable of real-time dosimetry is essential for optimizing treatment efficacy and minimizing collateral damage.&lt;/p&gt;&lt;p&gt;&lt;strong&gt;Purpose: &lt;/strong&gt;This study aimed to develop a high-resolution real-time boron dosimetry system for BNCT by employing a cadmium telluride double-sided strip detector (CdTe-DSD). The CdTe-DSD enables precise mapping of &lt;math&gt; &lt;semantics&gt; &lt;mrow&gt;&lt;msup&gt;&lt;mrow&gt;&lt;/mrow&gt; &lt;mn&gt;10&lt;/mn&gt;&lt;/msup&gt; &lt;mi&gt;B&lt;/mi&gt;&lt;/mrow&gt; &lt;annotation&gt;$^{10}{rm B}$&lt;/annotation&gt;&lt;/semantics&gt; &lt;/math&gt; distribution by detecting the 478 keV prompt &lt;math&gt;&lt;semantics&gt;&lt;mi&gt;γ&lt;/mi&gt; &lt;annotation&gt;$gamma$&lt;/annotation&gt;&lt;/semantics&gt; &lt;/math&gt; -rays emitted during the &lt;math&gt; &lt;semantics&gt; &lt;mrow&gt;&lt;msup&gt;&lt;mrow&gt;&lt;/mrow&gt; &lt;mn&gt;10&lt;/mn&gt;&lt;/msup&gt; &lt;mi&gt;B&lt;/mi&gt; &lt;msup&gt;&lt;mrow&gt;&lt;mo&gt;(&lt;/mo&gt; &lt;mi&gt;n&lt;/mi&gt; &lt;mo&gt;,&lt;/mo&gt; &lt;mi&gt;α&lt;/mi&gt; &lt;mo&gt;)&lt;/mo&gt;&lt;/mrow&gt; &lt;mn&gt;7&lt;/mn&gt;&lt;/msup&gt; &lt;mi&gt;Li&lt;/mi&gt;&lt;/mrow&gt; &lt;annotation&gt;$^{10}{rm B} ({rm n},alpha)^{7}{rm Li}$&lt;/annotation&gt;&lt;/semantics&gt; &lt;/math&gt;  reaction.&lt;/p&gt;&lt;p&gt;&lt;strong&gt;Methods: &lt;/strong&gt;The imaging system was constructed by integrating a CdTe-DSD with a 2-mm diameter pinhole collimator. The CdTe-DSD, comprising a 2-mm-thick CdTe semiconductor, has a sensitive area of 32 &lt;math&gt; &lt;semantics&gt;&lt;mrow&gt;&lt;mspace&gt;&lt;/mspace&gt; &lt;mo&gt;×&lt;/mo&gt; &lt;mspace&gt;&lt;/mspace&gt;&lt;/mrow&gt; &lt;annotation&gt;$,times ,$&lt;/annotation&gt;&lt;/semantics&gt; &lt;/math&gt; 32  &lt;math&gt; &lt;semantics&gt;&lt;msup&gt;&lt;mi&gt;mm&lt;/mi&gt; &lt;mn&gt;2&lt;/mn&gt;&lt;/msup&gt; &lt;annotation&gt;${rm mm}^2$&lt;/annotation&gt;&lt;/semantics&gt; &lt;/math&gt; . Neutron irradiation experiments were performed at Japan Research Reactor No. 3 using various boron-containing samples, including boric acid solutions, powders, and granular boron, with boron masses ranging from 0.02 to 2.00 mg. We implemented the neutron shields using a 5-mm-thick &lt;math&gt; &lt;semantics&gt; &lt;mrow&gt;&lt;msup&gt;&lt;mrow&gt;&lt;/mrow&gt; &lt;mn&gt;6&lt;/mn&gt;&lt;/msup&gt; &lt;msub&gt;&lt;mi&gt;Li&lt;/mi&gt; &lt;mn&gt;2&lt;/mn&gt;&lt;/msub&gt; &lt;msub&gt;&lt;mi&gt;CO&lt;/mi&gt; &lt;mn&gt;3&lt;/mn&gt;&lt;/msub&gt; &lt;/mrow&gt; &lt;annotation&gt;$^6{rm Li}_2{rm CO}_3$&lt;/annotation&gt;&lt;/semantics&gt; &lt;/math&gt; plate and LiF tiles to reduce the background from scattered neutrons during the measurement.&lt;/p&gt;&lt;p&gt;&lt;strong&gt;Results: &lt;/strong&gt;The imaging system successfully detected the 478 keV &lt;math&gt;&lt;semantics&gt;&lt;mi&gt;γ&lt;/mi&gt; &lt;annotation&gt;$gamma$&lt;/annotation&gt;&lt;/semantics&gt; &lt;/math&gt; -ray signal with an energy resolution of 7.3 keV at 511 keV. The reconstr","PeriodicalId":94136,"journal":{"name":"Medical physics","volume":"52 10","pages":"e70062"},"PeriodicalIF":3.2,"publicationDate":"2025-10-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145246077","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"A hybrid training database and evaluation benchmark for assessing metal artifact reduction methods for X-ray CT imaging.","authors":"Nils Peters, Eri Haneda, Jiayong Zhang, Grigorios Karageorgos, Wenjun Xia, Joost Verburg, Ge Wang, Harald Paganetti, Bruno De Man","doi":"10.1002/mp.70020","DOIUrl":"https://doi.org/10.1002/mp.70020","url":null,"abstract":"<p><strong>Background: </strong>Metal artifacts significantly degrade the image quality in computed tomography (CT) imaging, obscuring or even feigning pathology. While many different algorithms for metal artifact reduction (MAR) have been proposed, no comprehensive, clinically relevant evaluation benchmark exists. A major contributing factor to this is the lack of artifact-free ground truth data in clinical cases. Similarly, deep-learning based algorithms are hindered by the lack of paired training datasets with and without artifacts.</p><p><strong>Purpose: </strong>We propose the simulation of a large training database for deep-learning based MAR algorithms as well as the definition of a comprehensive evaluation benchmark for MAR. For this we utilize and validate a framework for the realistic simulation of metal artifacts on clinical CT data.</p><p><strong>Methods: </strong>A clinical and a generic CT scanner geometry is modelled in the CatSim CT simulator within the open-access toolkit XCIST. Since most MAR research is performed in 2D, all datasets are simulated in 2D. The metal artifact simulation capability is experimentally validated in CT phantom scans containing various metal types and -geometries. The tool is then used to simulate metal artifact scenarios as training data for deep-learning algorithms utilizing two public CT databases. Lastly, a benchmark is defined for clinically realistic metal artifact scenarios and applied to a numerical and a deep-learning based MAR algorithm, respectively.</p><p><strong>Results: </strong>Within specified regions of interest, the mean CT number deviation between simulation and real data was less than 2%, making the simulation tool suitable for the aspired tasks. In total, 14,000 metal scenarios in the head, thorax and pelvis regions were simulated. For the clinical benchmark, a set of metrics covering CT number accuracy, noise, image sharpness, streak amplitude, structural integrity, and the effect on range in proton therapy, were defined for a range of clinical scenarios. Metal scenarios covered the most relevant clinical use cases, covering small metal implants such as fiducial markers up to large metal implants such as hip replacements. Both the simulation tools and the benchmark with the test cases were made publicly available.</p><p><strong>Conclusions: </strong>We developed and distributed tools and datasets for the development and evaluation of MAR algorithms. This is the first comprehensive evaluation benchmark covering a large number of clinically realistic metal artifact scenarios.</p>","PeriodicalId":94136,"journal":{"name":"Medical physics","volume":"52 10","pages":"e70020"},"PeriodicalIF":3.2,"publicationDate":"2025-10-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145246087","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"An end-to-end CT simulation framework with graphical user interface and sample scanner models.","authors":"Amar Kavuri, Milo Fryling, Nicholas Felice, Lior Malvin, Darin P Clark, Ehsan Samei, Ehsan Abadi","doi":"10.1002/mp.70066","DOIUrl":"https://doi.org/10.1002/mp.70066","url":null,"abstract":"<p><strong>Background: </strong>Virtual imaging trials (VIT) facilitate medical imaging experimentation through computational models of patients and scanning equipment. For broad adoption across the medical imaging community, VIT tools should not only be accurate but also robust and user-friendly.</p><p><strong>Purpose: </strong>To develop a validated, end-to-end CT simulation framework with script-based and graphical user interfaces (GUIs), packaged for simple installation and robust performance across diverse computing environments.</p><p><strong>Methods: </strong>A previously-validated CT simulator (DukeSim) was packaged into an end-to-end framework with four major components: (1) a web-based GUI inspired by clinical scanner consoles, (2) a Python wrapper script serving as a flexible entry point, (3) a physics-based CT projector utilizing ray-tracing and Monte Carlo methods, and (4) a vendor-neutral reconstruction module (MCR Toolkit) supporting both filtered back-projection and iterative techniques. The web-based GUI was developed based on NodeJS and Express server configuration to select the protocol and scanner configurations and to initiate the CT simulations. The integrated DukeSim software was built in three types of packages, with rigorous version control, testing, bug tracking, and release processes. Further, the software's capabilities and potential utilities were demonstrated by developing sample scanner models mimicking the attributes of legacy CT scanners.</p><p><strong>Results: </strong>The integrated CT simulation framework was successfully developed, enabling seamless adoption and broad applicability in virtual imaging trials. Additionally, the modeling and validation of legacy scanners demonstrated the framework's capability to accurately represent a variety of clinically relevant scanners.</p><p><strong>Conclusions: </strong>This work represents a major advancement in CT simulation tools, providing an end-to-end, validated, and robust solution for virtual imaging trials. The software's flexibility to model various CT technologies, combined with its user-friendly interface and validated accuracy, positions it as a valuable tool for advancing research in CT technology development, assessment, and optimization.</p>","PeriodicalId":94136,"journal":{"name":"Medical physics","volume":"52 10","pages":"e70066"},"PeriodicalIF":3.2,"publicationDate":"2025-10-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145246099","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Development and dosimetric verification of static SHArc: Step-and-shoot carbon ion arc therapy for LET_d escalation in pancreatic tumors.","authors":"Filipa Baltazar, Thomas Tessonnier, Stewart Mein, Jakob Liermann, Abdallah Qubala, Jürgen Debus, Andrea Mairani","doi":"10.1002/mp.70055","DOIUrl":"https://doi.org/10.1002/mp.70055","url":null,"abstract":"<p><strong>Background: </strong>Carbon ion radiotherapy (CIRT) offers higher linear energy transfer (LET) and superior relative biological effectiveness, making it a promising option for treating hypoxic, radioresistant tumors. Spot-scanning Hadron Arc (SHArc) therapy enables dose-averaged LET (LET_d) escalation in the tumor but increases planning and setup complexity. Dynamic delivery remains impractical for gantry-based carbon ion arc therapy due to the system's large size and complex control requirements. Step-and-shoot delivery, while less efficient, provides a feasible alternative and represents a key step towards clinical SHArc implementation.</p><p><strong>Purpose: </strong>This work establishes the first step-and-shoot planning and delivery technique for carbon ion arc therapy (static SHArc) at the Heidelberg Ion-beam Therapy Center using the gantry system. Static SHArc therapy is evaluated in terms of plan quality and delivery feasibility for pancreatic cancer.</p><p><strong>Methods: </strong>Static SHArc plans were optimized for seven pancreatic cancer cases, considering 20 gantry angles. Two distinct energy layer (EL) selection techniques were investigated: (1) Central EL, selecting the seven central ELs per beam, and (2) MU-Based EL, prioritizing ELs contributing the highest monitor units (MU). LET_d optimization was performed to escalate the minimum LET_d to ∼50-80 keV/µm within the gross tumor volume. Static SHArc plans were compared against conventional IMPT using two single-field optimized posterior oblique beams (2-SFO), in terms of dose conformality, LET_d, and robustness against setup (5 mm) and range (1.5%) uncertainties. Inter-fractional robustness was assessed via forward dose calculation on daily control CT scans. Dosimetric validation and delivery time verification for static SHArc using the heavy ion gantry system were conducted via end-to-end testing with ion chamber and film measurements in a cylindrical PMMA phantom.</p><p><strong>Results: </strong>Static SHArc plans improved LET_d distributions in the tumor without compromising target coverage and clinical OAR constraints. The MU-based EL method increased minimum target dose, whereas Central EL enabled higher LET_d concentration in the tumor center. Both energy selection methods for static SHArc exhibited reduced inter-fractional robustness compared to the two-SFO. Dosimetric verification showed deviations < 3% and total delivery time was ∼27 min.</p><p><strong>Conclusions: </strong>This study investigates static SHArc, a step-and-shoot approach for delivering carbon ion arc therapy. While static SHArc can provide dosimetric advantages, particularly in terms of LET_d distribution, EL selection plays a key role. Improving inter-fraction robustness remains crucial for clinical implementation.</p>","PeriodicalId":94136,"journal":{"name":"Medical physics","volume":"52 10","pages":"e70055"},"PeriodicalIF":3.2,"publicationDate":"2025-10-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145246085","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}