Journal of Applied Clinical Medical Physics最新文献

{"title":"Characterizing geometrical distortions in MRI for radiotherapy: Evaluating MR-SIM protocols and dose accuracy in stereotactic radiosurgery using AAPM TG-284 criteria","authors":"Mojtaba Barzegar,&nbsp;Aram Rostami,&nbsp;Abbass Yousef Mkanna,&nbsp;Tarraf Torfeh,&nbsp;Satheesh Prasad Paloor,&nbsp;Ahamed Basith,&nbsp;Souha Aouadi,&nbsp;Rabih Hammoud,&nbsp;Noora Al Hammadi","doi":"10.1002/acm2.70199","DOIUrl":"10.1002/acm2.70199","url":null,"abstract":"<div>\u0000 \u0000 \u0000 <section>\u0000 \u0000 <h3> Objective</h3>\u0000 \u0000 <p>Magnetic resonance imaging (MRI) is crucial for diagnostic imaging and radiotherapy (RT) planning due to its superior soft tissue contrast. However, geometric distortions can affect treatment accuracy. This study evaluates the geometric accuracy of MRI protocols using a 1.5T MR-Sim scanner for RT and their dosimetric impacts.</p>\u0000 </section>\u0000 \u0000 <section>\u0000 \u0000 <h3> Materials and Methods</h3>\u0000 \u0000 <p>Geometric distortion was assessed using the CIRS 604-GS MR Image Distortion Phantom with 2152 control points across various MRI sequences. A central cubic structure and surrounding regions were analyzed, totaling 27 structures. Rigid registration in Eclipse V18.1 aligned MRI images to CT images, with verified accuracy and visual inspection. An evaluation of the overlap and surface distance metrics was performed through MIM Mastro. Geometric distortion was quantified using 3D distortion analysis software, comparing marker coordinates to reference CT scans. Twenty-seven VMAT full arc plans were done in Eclipse on 27 paired structures, irradiated with 16 Gy in a single fraction at 6 MV energy using the Acuros XB algorithm</p>\u0000 </section>\u0000 \u0000 <section>\u0000 \u0000 <h3> Results</h3>\u0000 \u0000 <p>All 3D sequences demonstrated mean distortions of 0.4–0.5 mm, with maximum distortions of up to 3.3 mm in the TOF (time of flight) Angiography sequence. In contrast, the T2 TSE 2D sequence showed larger distortions (mean 1.4 mm, max. 9.7 mm). The center structure showed stable dosimetric performance (D_mean: 1601.6 cGy for CT, 1600.3 cGy for MR). Peripheral regions showed higher variability, with MR_normalized D_95% values ranging from 83.9% to 88.1%.</p>\u0000 </section>\u0000 \u0000 <section>\u0000 \u0000 <h3> Conclusion</h3>\u0000 \u0000 <p>Precise MR protocols are essential for accurate tumor delineation and RT planning. While all sequences showed acceptable accuracy, 3D sequences are superior for high-precision RT.</p>\u0000 </section>\u0000 </div>","PeriodicalId":14989,"journal":{"name":"Journal of Applied Clinical Medical Physics","volume":"26 10","pages":""},"PeriodicalIF":2.2,"publicationDate":"2025-09-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.ncbi.nlm.nih.gov/pmc/articles/PMC12481828/pdf/","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145199378","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"医学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Monte Carlo analysis of energy deposition and X-ray fluence in cylindrical anode systems","authors":"M. K. M. Alharbi,&nbsp;Abel Zhou,&nbsp;Rob Davidson,&nbsp;Mark Naunton,&nbsp;Chandra Makanjee","doi":"10.1002/acm2.70262","DOIUrl":"10.1002/acm2.70262","url":null,"abstract":"<div>\u0000 \u0000 \u0000 <section>\u0000 \u0000 <h3> Background</h3>\u0000 \u0000 <p>Cylindrical anode X-ray systems are increasingly used in multisource imaging; however, electron beam interactions with the curved anodes cause geometric distortions that alter energy deposition and X-ray emission. Understanding these effects is key to optimizing system performance.</p>\u0000 </section>\u0000 \u0000 <section>\u0000 \u0000 <h3> Purpose</h3>\u0000 \u0000 <p>This study uses Monte Carlo (MC) simulations to examine how electron beam size, anode radius, and polar angle influence energy deposition and X-ray fluence in cylindrical anode setups, and to quantify the distortions and energy redistribution for improved X-ray generation efficiency and beam stability.</p>\u0000 </section>\u0000 \u0000 <section>\u0000 \u0000 <h3> Methods</h3>\u0000 \u0000 <p>MC simulations were performed with electron beams (0.5 × 0.5 mm and 2 × 2 mm, 120 keV) on cylindrical tungsten anodes with radii from 1 to 5 cm and polar angles from 20.5° to 71.8°. Energy deposition profiles, dimensions, and photon fluence distributions were analyzed using the FLUKA MC package, with mapping in cylindrical coordinates (<i>r</i>-<i>ϕ</i>-<i>z</i>).</p>\u0000 </section>\u0000 \u0000 <section>\u0000 \u0000 <h3> Results</h3>\u0000 \u0000 <p>Energy deposition profiles varied with beam position and anode curvature. The axial full width at half maximum (FWHM) increased by up to 650% at larger polar angles, while the azimuthal FWHM decreased up to 50%. Larger anode radii reduced the azimuthal FWHM by up to 78%, with minimal changes in axial and radial components. Narrower beams (0.5 × 0.5 mm²) produced smaller, more symmetric energy deposition profiles on anode surface. Overshoot occurred at small radii and large polar angles, leading to incomplete energy deposition.</p>\u0000 </section>\u0000 \u0000 <section>\u0000 \u0000 <h3> Conclusions</h3>\u0000 \u0000 <p>Larger anode radii and moderate polar angles minimized energy deposition profiles distortion and improved X-ray fluence uniformity and production efficiency. Overshooting at small radii and large angles caused deformation, emphasizing the need for precise beam positioning to balance distortion, uniformity, and efficiency. These results define the geometric limits for effective energy deposition profile formation in cylindrical anode systems.</p>\u0000 </section>\u0000 </div>","PeriodicalId":14989,"journal":{"name":"Journal of Applied Clinical Medical Physics","volume":"26 10","pages":""},"PeriodicalIF":2.2,"publicationDate":"2025-09-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.ncbi.nlm.nih.gov/pmc/articles/PMC12483768/pdf/","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145199462","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"医学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Quality assurance of single isocentre multiple target stereotactic radiosurgery: Findings from long-term off-axis Winston-Lutz testing and machine performance checks","authors":"Joel Poder,&nbsp;Robert Chambers,&nbsp;Harry Porter,&nbsp;Ryan Brown,&nbsp;Dylan Koprivec,&nbsp;Johnson Yuen,&nbsp;Rebecca Quezeda,&nbsp;Lisa Nourbehesht,&nbsp;Andrew Howie","doi":"10.1002/acm2.70275","DOIUrl":"10.1002/acm2.70275","url":null,"abstract":"<div>\u0000 \u0000 \u0000 <section>\u0000 \u0000 <h3> Background</h3>\u0000 \u0000 <p>Single-isocenter multiple-target stereotactic radiosurgery (SIMT SRS) has emerged as an efficient treatment for multiple brain metastases. However, this technique demands exceptional geometric accuracy, particularly off-axis, to ensure optimal dose delivery while sparing healthy tissue. Traditional quality assurance (QA) methods require adaptation for SIMT SRS, highlighting the need for robust testing protocols.</p>\u0000 </section>\u0000 \u0000 <section>\u0000 \u0000 <h3> Purpose</h3>\u0000 \u0000 <p>This study aimed to evaluate the long-term off-axis targeting accuracy of three Varian TrueBeam linear accelerators using a dedicated off-axis Winston–Lutz test (OAWLT) and to investigate correlations with routine varian machine performance check (MPC) results.</p>\u0000 </section>\u0000 \u0000 <section>\u0000 \u0000 <h3> Materials &amp; Methods</h3>\u0000 \u0000 <p>Weekly OAWLT measurements were performed over a 6-month period on three TrueBeam linacs using the Sun Nuclear StereoPHAN phantom and MultiMet-WL cube. The test delivered 6 MV flattening filter-free beams to multiple off-axis targets via eight beam orientations, simulating clinical SIMT SRS workflows. Concurrently, daily MPC assessments evaluated geometric parameters including isocenter size, kV isocenter offset, beam center, and couch radiation-induced offset.</p>\u0000 </section>\u0000 \u0000 <section>\u0000 \u0000 <h3> Results</h3>\u0000 \u0000 <p>Median OAWLT errors were 0.38, 0.44, and 0.59 mm for the three linacs included in this study, with maximum errors of 1.12, 1.08, and 1.54 mm. Notably, off-axis errors increased with target off-axis distance, with the worst performance observed at 7 cm off-axis.</p>\u0000 </section>\u0000 \u0000 <section>\u0000 \u0000 <h3> Conclusion</h3>\u0000 \u0000 <p>Routine OAWLT is an effective and sensitive QA tool for monitoring off-axis targeting accuracy in SIMT SRS. Despite the convenience of daily MPC, it cannot substitute for a dedicated OAWLT. The study supports implementing weekly OAWLT in clinical practice to ensure high-quality, consistent treatment delivery for SIMT SRS treatments.</p>\u0000 </section>\u0000 </div>","PeriodicalId":14989,"journal":{"name":"Journal of Applied Clinical Medical Physics","volume":"26 10","pages":""},"PeriodicalIF":2.2,"publicationDate":"2025-09-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.ncbi.nlm.nih.gov/pmc/articles/PMC12483765/pdf/","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145199379","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"医学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Comparison of liver stereotactic body radiotherapy plans based on free breathing and averaged CTs after trans-arterial chemoembolization using lipiodol","authors":"Sei-Kwon Kang,&nbsp;Jai-Woong Yoon,&nbsp;Me Young Kim,&nbsp;Soah Park,&nbsp;Kwang-Ho Cheong,&nbsp;Taeryool Koo,&nbsp;Tae Jin Han","doi":"10.1002/acm2.70271","DOIUrl":"10.1002/acm2.70271","url":null,"abstract":"<div>\u0000 \u0000 \u0000 <section>\u0000 \u0000 <h3> Purpose</h3>\u0000 \u0000 <p>To identify which CT set is more suitable for predicting the four-dimensional (4D) cumulative dose distribution in liver stereotactic body radiotherapy (SBRT) with lipiodol retention.</p>\u0000 </section>\u0000 \u0000 <section>\u0000 \u0000 <h3> Methods</h3>\u0000 \u0000 <p>For 15 patients, who underwent liver SBRT after trans-arterial chemoembolization (TACE), volumetric modulated arc therapy (VMAT) plans were retrospectively generated on free breathing (FB) and average intensity projection (AVG) CT sets using the x-ray Voxel Monte Carlo (XVMC) algorithm. The three-dimensional (3D) FB and AVG plans were compared with corresponding 4D plans, which were created by deformable registration using 10-phase plans. For both internal target volume (ITV) and planning target volume (PTV), the volume covered by the prescription dose of 36 Gy (V36) and the dose covering 95% of the volume (D95) were evaluated. The relative (3D/4D) normal liver volume &gt;19.2 Gy and rib volume 28.8 Gy were also compared for FB and AVG plans.</p>\u0000 </section>\u0000 \u0000 <section>\u0000 \u0000 <h3> Results</h3>\u0000 \u0000 <p>The mean values of the relative electron densities inside the PTV for FB and AVG were slightly different (1.050 for FB vs. 1.039 for AVG). For both ITV and PTV, V36 and D95 showed no statistically significant difference between FB and AVG. Also, the relative rib volumes &gt;28.8 Gy and the normal liver volumes &gt;19.2 Gy were not statistically different between FB and AVG plans.</p>\u0000 </section>\u0000 \u0000 <section>\u0000 \u0000 <h3> Conclusion</h3>\u0000 \u0000 <p>For liver SBRT with lipiodol retention, 3D plans based on FB and AVG images were virtually equivalent in producing the 4D cumulative doses under the accuracy of the XVMC algorithm.</p>\u0000 </section>\u0000 </div>","PeriodicalId":14989,"journal":{"name":"Journal of Applied Clinical Medical Physics","volume":"26 10","pages":""},"PeriodicalIF":2.2,"publicationDate":"2025-09-29","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.ncbi.nlm.nih.gov/pmc/articles/PMC12479210/pdf/","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145191627","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"医学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Pre-irradiation dose requirements for reference-class ionization chambers: Quantifying measurement stability","authors":"Takumi Yamada,&nbsp;Kazuki Mayumi,&nbsp;Satoshi Tanabe,&nbsp;Takayuki Nishikata,&nbsp;Naoki Kinoshita,&nbsp;Tatsuya Sakai,&nbsp;Hironori Sakai,&nbsp;Tetsuya Oka,&nbsp;Hiroyuki Ishikawa,&nbsp;Tsutomu Kanazawa","doi":"10.1002/acm2.70273","DOIUrl":"10.1002/acm2.70273","url":null,"abstract":"<div>\u0000 \u0000 \u0000 <section>\u0000 \u0000 <h3> Background</h3>\u0000 \u0000 <p>Pre-irradiation of ionization chambers is widely recommended to stabilize output readings for reference dosimetry in radiation therapy. However, the specific pre-irradiation requirements for different chamber models, particularly under strictly controlled conditions that isolate chamber performance, remain unclear.</p>\u0000 </section>\u0000 \u0000 <section>\u0000 \u0000 <h3> Purpose</h3>\u0000 \u0000 <p>This study aimed to quantitatively evaluate the pre-irradiation dose required to stabilize the output of various reference-class ionization chambers, while minimizing the influence of environmental and system-level uncertainties.</p>\u0000 </section>\u0000 \u0000 <section>\u0000 \u0000 <h3> Methods</h3>\u0000 \u0000 <p>Twelve reference-class ionization chambers (Exradin A12, A1SL; IBA CC13, FC65G; PTW 30013, 31021) were evaluated under strictly controlled conditions (room temperature: 25 ± 1°C, water temperature: 25.00 ± 0.01°C, relative humidity: approximately 50%). Output stability was assessed using a 10 MV photon beam from a TrueBeam linac. Chamber readings were measured using an RT521R2 electrometer and normalized to an adjacent external monitor chamber. Readings are defined as stable if the reading variation is &lt;0.1% and does not exhibit any trending. The optimal number of pre-irradiation exposures and corresponding doses were determined for each chamber.</p>\u0000 </section>\u0000 \u0000 <section>\u0000 \u0000 <h3> Results</h3>\u0000 \u0000 <p>For the large-volume chambers (Exradin A12, IBA FC65G, PTW 30013), output variation was within ±0.05% from the first irradiation, suggesting that pre-irradiation may be unnecessary. In contrast, the middle-volume class ionization chambers (Exradin A1SL, IBA CC13, PTW 31021) exhibited variations of up to ±0.25%, and required up to 100 MU × 25 (approximately 21.25 Gy) of pre-irradiation to achieve stability under the controlled experimental conditions of this study.</p>\u0000 </section>\u0000 \u0000 <section>\u0000 \u0000 <h3> Conclusions</h3>\u0000 \u0000 <p>This study demonstrated that the required pre-irradiation dose varies depending on the type of ionization chamber, and that the output variation is significantly lower than the previously reported 1%. These results may help streamline clinical reference dosimetry by tailoring procedures to each chamber.</p>\u0000 </section>\u0000 </div>","PeriodicalId":14989,"journal":{"name":"Journal of Applied Clinical Medical Physics","volume":"26 10","pages":""},"PeriodicalIF":2.2,"publicationDate":"2025-09-29","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.ncbi.nlm.nih.gov/pmc/articles/PMC12479200/pdf/","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145191632","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"医学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Breath-holding treatments in tomotherapy with active breathing coordinator: A first case report","authors":"April Meikwan Chow,&nbsp;Ashley Chi Kin Cheng,&nbsp;Louis Kit Yee Lee","doi":"10.1002/acm2.70270","DOIUrl":"10.1002/acm2.70270","url":null,"abstract":"<div>\u0000 \u0000 \u0000 <section>\u0000 \u0000 <h3> Purpose</h3>\u0000 \u0000 <p>Respiratory motion poses a significant challenge in radiation therapy for thoracic and abdominal malignancies. For tomotherapy machines, it is even more challenging due to the 10-s warm-up time before initiating the treatment beams. A recent tomotherapy system upgrade has reduced this warm-up time to 0.5 s for the TomoDirect delivery mode, enabling the feasibility of performing breath-holding treatments. In this study, we investigated the feasibility of performing breath-holding treatments on a tomotherapy machine with spirometry technique.</p>\u0000 </section>\u0000 \u0000 <section>\u0000 \u0000 <h3> Methods</h3>\u0000 \u0000 <p>A patient with gastric mucosa-assisted lymphoid tissue lymphoma was treated with deep inspiration breath holding (30 Gy in 20 fractions) on a tomotherapy machine with Active Breathing Coordinator™. An in-house visual system, featuring a compact 7″ LCD monitor, was implemented to provide visual feedback, allowing the patient to self-monitor their breathings and adhere to the prescribed pattern.</p>\u0000 </section>\u0000 \u0000 <section>\u0000 \u0000 <h3> Results</h3>\u0000 \u0000 <p>The patient tolerated the breath-hold well for the entire treatment. The number of breath-holds for treatment was 9. The beam-on time for each field ranged from 12.4 to 19.7 s, average 15.2 s.</p>\u0000 </section>\u0000 \u0000 <section>\u0000 \u0000 <h3> Conclusions</h3>\u0000 \u0000 <p>We have shown that BH treatment is feasible using an upgraded tomotherapy machine (Radixact v3.5) with Active Breathing Coordinator. Our proposed workflow includes an in-house visual system that allows patients to visualize their breathing patterns on-screen. This technique provides a practical solution for patients with thoracic and abdominal malignancies, addressing respiratory motion while minimizing radiation exposure for certain diseases.</p>\u0000 </section>\u0000 </div>","PeriodicalId":14989,"journal":{"name":"Journal of Applied Clinical Medical Physics","volume":"26 10","pages":""},"PeriodicalIF":2.2,"publicationDate":"2025-09-29","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.ncbi.nlm.nih.gov/pmc/articles/PMC12479219/pdf/","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145191618","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"医学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"The suitability of radiomics extracted from 4DCT motion-compensated reconstruction","authors":"Chelsea A. H. Sargeant,&nbsp;Angela Davey,&nbsp;Alan McWilliam","doi":"10.1002/acm2.70254","DOIUrl":"10.1002/acm2.70254","url":null,"abstract":"<div>\u0000 \u0000 \u0000 <section>\u0000 \u0000 <h3> Purpose</h3>\u0000 \u0000 <p>The most appropriate 4DCT image for radiomics analysis remains uncertain, with options including individual respiratory phases and motion-compensated (MC) reconstructions. This study compares radiomic features derived from MC reconstructions and patient-specific, 4D phases, evaluating their influence on feature selection, robustness to registration algorithms and implications for radiomics analysis.</p>\u0000 </section>\u0000 \u0000 <section>\u0000 \u0000 <h3> Methods</h3>\u0000 \u0000 <p>This study included 223 NSCLC patients. MC reconstructions (MC_mean and MC_median) were generated using three different registration algorithms and compared to a patient-specific optimal 4D phase (TOp), defined as the phase where radiomic feature values exhibited the smallest variability. Ninety-three features, extracted from the tumor region, underwent unsupervised selection to assess how image type influenced feature selection and redundancy. The impact of image type on distant failure prediction was evaluated using bootstrapped univariable Cox regression (<i>p</i> &lt; 0.05) and multivariable modeling. Model performance was assessed across 500 bootstrap resamples, with feature selection frequency, concordance index (CI), and Akaike Information Criterion (AIC) recorded.</p>\u0000 </section>\u0000 \u0000 <section>\u0000 \u0000 <h3> Results</h3>\u0000 \u0000 <p>Over 60% of selected features differed between 4D phases and MC reconstructions, indicating image type influences feature selection. The proportion of remaining features varied: 11.8% (TOp), 15.1% (MC_mean), and 12.9% (MC_median). The single-phase model, TOp, achieved a CI of 0.72 [0.64–0.77] and an AIC of 267.53, but did not demonstrate clear superiority over MC-based models. Both MC_median and TOp showed modest improvements over the clinical model, suggesting both image types offer comparable prognostic potential. MC reconstructions were largely robust across registration algorithms, but MC_mean and MC_median reconstructions should not be used interchangeably.</p>\u0000 </section>\u0000 \u0000 <section>\u0000 \u0000 <h3> Conclusion</h3>\u0000 \u0000 <p>This study highlights differences in radiomic feature selection and predictive performance between MC reconstructions and individual 4DCT phases. MC reconstructions were a viable alternative, demonstrating robustness across registration algorithms. Both approaches can be integrated into radiomics pipelines, but image type selection should be carefully considered.</p>\u0000 </section>\u0000 </div>","PeriodicalId":14989,"journal":{"name":"Journal of Applied Clinical Medical Physics","volume":"26 10","pages":""},"PeriodicalIF":2.2,"publicationDate":"2025-09-29","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.ncbi.nlm.nih.gov/pmc/articles/PMC12479209/pdf/","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145191665","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"医学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Evaluation of image quality in mobile cone-beam CT with dose modulation using automatic exposure control: A phantom study","authors":"Keita Okazaki,&nbsp;Wenchao Cao,&nbsp;Reza Taleei,&nbsp;Firas Mourtada,&nbsp;Jun Li,&nbsp;Karen Mooney,&nbsp;Pramila Rani Anne,&nbsp;Yingxuan Chen","doi":"10.1002/acm2.70248","DOIUrl":"10.1002/acm2.70248","url":null,"abstract":"<div>\u0000 \u0000 \u0000 <section>\u0000 \u0000 <h3> Background</h3>\u0000 \u0000 <p>The integration of mobile cone-beam computed tomography (CBCT) into brachytherapy workflows offers clinical advantages such as immediate verification of applicator placement and adaptive treatment planning. These benefits require sufficient image quality to delineate applicators, target volumes, and organs at risk. A systematic evaluation of automatic exposure control (AEC) settings, radiation dose, and image quality is essential to ensure clinically acceptable imaging while minimizing patient exposure.</p>\u0000 </section>\u0000 \u0000 <section>\u0000 \u0000 <h3> Purpose</h3>\u0000 \u0000 <p>This study evaluates the characteristics of AEC and its impact on image quality and radiation dose in a mobile CBCT system used for brachytherapy.</p>\u0000 </section>\u0000 \u0000 <section>\u0000 \u0000 <h3> Methods</h3>\u0000 \u0000 <p>The Elekta ImagingRing CBCT system was used to scan a CatPhan phantom under two imaging protocols: Medium Dose Limit (MDL) and Ultra-High Dose Limit (UHDL). This system employs a two-layer mAs modulation process, consisting of preset mA values based on body mass index (BMI) and adjusted mA based on real-time AEC. A bolus was used to simulate larger patient sizes. Real-time x-ray tube current at 10 degrees intervals was recorded. Image quality was evaluated using image noise, noise power spectrum (NPS), modulation transfer function (MTF), Hounsfield Unit (HU) linearity, uniformity index (UI), and contrast-to-noise ratio (CNR) across different protocols.</p>\u0000 </section>\u0000 \u0000 <section>\u0000 \u0000 <h3> Results</h3>\u0000 \u0000 <p>AEC effectively modulated x-ray tube current in the MDL protocol after x-ray attenuation through the scanned phantom was measured. The UHDL protocol demonstrated greater noise reduction than the MDL. MTF values were comparable between protocols, indicating preserved spatial resolution in the MDL protocol. HU linearity was consistent across all protocols, with <i>R</i>² &gt; 0.993.</p>\u0000 </section>\u0000 \u0000 <section>\u0000 \u0000 <h3> Conclusion</h3>\u0000 \u0000 <p>AEC in mobile CBCT optimized radiation dose and image quality by adjusting tube current based on attenuation. The MDL protocol reduced radiation exposure while maintaining image quality, making it a viable option for verifying applicator placement and treatment planning in brachytherapy. The UHDL protocol achieved noise reduction with the maximum available tube current.</p>\u0000 </section>\u0000 </div>","PeriodicalId":14989,"journal":{"name":"Journal of Applied Clinical Medical Physics","volume":"26 10","pages":""},"PeriodicalIF":2.2,"publicationDate":"2025-09-28","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.ncbi.nlm.nih.gov/pmc/articles/PMC12476867/pdf/","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145185630","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"医学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"First experience with third-party validations: A robust calibration and QA procedure for proton FLASH delivery","authors":"Chih-Chiang Chang,&nbsp;Balaji Selvaraj,&nbsp;Xingyi Zhao,&nbsp;Jacob Rembish,&nbsp;Paige A. Taylor,&nbsp;Alexander Bookbinder,&nbsp;Chingyun Cheng,&nbsp;J. Isabelle Choi,&nbsp;Charles B. Simone II,&nbsp;Haibo Lin,&nbsp;Minglei Kang","doi":"10.1002/acm2.70269","DOIUrl":"https://doi.org/10.1002/acm2.70269","url":null,"abstract":"<div>\u0000 \u0000 \u0000 <section>\u0000 \u0000 <h3> Background</h3>\u0000 \u0000 <p>Proton FLASH radiotherapy, delivering ultra-high dose rates, shows promise in reducing normal tissue toxicity while maintaining tumor control. However, accurate dosimetry and quality assurance (QA) for FLASH remain challenging due to the extreme dose rates involved. Developing reliable calibration and QA procedures is crucial for advancing FLASH towards clinical implementation.</p>\u0000 </section>\u0000 \u0000 <section>\u0000 \u0000 <h3> Purpose</h3>\u0000 \u0000 <p>To present an effective routine calibration and QA procedure for proton FLASH delivery to ensure high-quality dosimetry performance for preclinical and clinical delivery.</p>\u0000 </section>\u0000 \u0000 <section>\u0000 \u0000 <h3> Methods</h3>\u0000 \u0000 <p>A high temporospatial resolution strip ionization chamber array (SICA) detector was mounted to the treatment nozzle, which was calibrated using an Advanced Markus ion chamber (IC) under variable dose and ultra-high dose rates. The calibration curve was used to monitor the delivery in real-time. The maximum beam current was 215 nA at the isocenter at the highest energy of the cyclotron (250 MeV). Third-party IROC (Imaging and Radiation Oncology Core) thermoluminescent dosimeters (TLDs) were requested to verify the accuracy and effectiveness of the calibration and validation procedure. A transmission field with a field size of 3 × 3 cm² was designed to deliver 2000 cGy doses with a field-averaged dose rate varying from 36 to 76.5 Gy/s.</p>\u0000 </section>\u0000 \u0000 <section>\u0000 \u0000 <h3> Results</h3>\u0000 \u0000 <p>The entire calibration process took less than 10 minutes as part of routine daily QA. The calibration curve between the SICA detector and IC demonstrated an <i>R</i>-value of almost 1.00. The SICA detector measured each delivery, providing critical data for FLASH analysis, including field size, dose, delivery time, and dose rate. Based on real-time dose and dose rate monitoring, the planned and delivered doses were within 1% accuracy according to third-party TLD measurements.</p>\u0000 </section>\u0000 \u0000 <section>\u0000 \u0000 <h3> Conclusion</h3>\u0000 \u0000 <p>As demonstrated by IROC measurements, effective calibration and QA using a SICA detector for proton FLASH delivery can ensure high accuracy in real-time dose and dose rate monitoring, paving the way for future clinical applications.</p>\u0000 </section>\u0000 </div>","PeriodicalId":14989,"journal":{"name":"Journal of Applied Clinical Medical Physics","volume":"26 10","pages":""},"PeriodicalIF":2.2,"publicationDate":"2025-09-27","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://aapm.onlinelibrary.wiley.com/doi/epdf/10.1002/acm2.70269","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145146998","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"医学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Human visual perception-based grayscale contrast enhancement with adaptive window settings in computed tomography images","authors":"Wei Zhou,&nbsp;Yi Tian","doi":"10.1002/acm2.70212","DOIUrl":"10.1002/acm2.70212","url":null,"abstract":"<div>\u0000 \u0000 \u0000 <section>\u0000 \u0000 <h3> Background</h3>\u0000 \u0000 <p>Grayscale contrast plays a significant role in medical imaging. This is due to the fact that visual examination, where images are represented with different gray shades on display devices, is essential in current medical applications.</p>\u0000 </section>\u0000 \u0000 <section>\u0000 \u0000 <h3> Purpose</h3>\u0000 \u0000 <p>The effective contrast enhancement should have the ability to provide sufficient grayscale contrast and natural image appearance in line with human visual perception (HVP). To achieve the goal, the paper proposes a novel method for grayscale contrast improvement in computed tomography (CT) diagnostics.</p>\u0000 </section>\u0000 \u0000 <section>\u0000 \u0000 <h3> Methods</h3>\u0000 \u0000 <p>A new quantitative physical metric incorporating certain human visual characteristics, termed as contrast-perceived to spatial frequency ratio (CPSFR), is presented to assess the perceptual quality of grayscale-based images. The window settings achieved by maximizing CPSFR, <i>Window Settings Automatic</i>, was evaluated and compared with <i>Window Settings Preset</i> and <i>Window Settings Manual</i> both of which are most used in CT diagnostics in terms of target detectability and diagnostic satisfaction. Experiments were carried out with 720 phantom images and 80 patient images. In phantom study, images were acquired with the routine body protocol at varying dose levels and assessed by four CT physicists for identifying signal-present or signal-absent. In clinical study, images with liver lesions were evaluated and rated by three radiologists with a 4-point diagnostic quality score.</p>\u0000 </section>\u0000 \u0000 <section>\u0000 \u0000 <h3> Results</h3>\u0000 \u0000 <p>The phantom study indicated a statistically significant improvement with <i>Window Settings Automatic</i>, as compared to <i>Window Settings Preset</i> and <i>Window Settings Manual</i> (all <i>p &lt;</i> 0.01) in accuracy and sensitivity for consensus readings. And the clinical study demonstrated <i>Window Settings Automatic</i> had the distinct advantage over other candidates (highest mean score 3.0; <i>&gt;</i> 40% of all top-scoring votes).</p>\u0000 </section>\u0000 \u0000 <section>\u0000 \u0000 <h3> Conclusions</h3>\u0000 \u0000 <p>The proposed method is capable of enhancing grayscale contrast in the region that really interests observers and yielding natural image appearance well suited to human visual perception to improve target detectability and diagnostic performance.</p>\u0000 </section>\u0000 </div>","PeriodicalId":14989,"journal":{"name":"Journal of Applied Clinical Medical Physics","volume":"26 10","pages":""},"PeriodicalIF":2.2,"publicationDate":"2025-09-25","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://aapm.onlinelibrary.wiley.com/doi/epdf/10.1002/acm2.70212","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145137529","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"医学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}