Medical physics最新文献

{"title":"Capture-enhanced neutron irradiation to treat Alzheimer's disease: Design of a small animal set-up for future in-vivo experiments","authors":"Valeria Pascali, Davide Tosoni, Saverio Altieri, Nicoletta Protti","doi":"10.1002/mp.18062","DOIUrl":"https://doi.org/10.1002/mp.18062","url":null,"abstract":"<div>\u0000 \u0000 \u0000 <section>\u0000 \u0000 <h3> Background</h3>\u0000 <p>Alzheimer's disease (AD) is characterized by the accumulation of <span></span><math>\u0000 <semantics>\u0000 <mi>β</mi>\u0000 <annotation>$beta$</annotation>\u0000 </semantics></math>-Amyloid and <span></span><math>\u0000 <semantics>\u0000 <mi>τ</mi>\u0000 <annotation>$tau$</annotation>\u0000 </semantics></math> proteins in the brain that causes dementia. To date, there is no cure capable of eradicating AD, so it is necessary to study a performing therapy. The NECTAR project aims to investigate an extension of the conventional Boron Neutron Capture Therapy principles as a possible treatment for AD at different scales (protein, cells, animal).</p>\u0000 </section>\u0000 \u0000 <section>\u0000 \u0000 <h3> Purpose</h3>\u0000 <p>The present study focuses on a macroscopic scale and wants to propose an irradiation set-up for mice in the thermal column (TC) of the Triga Mark II reactor of Pavia University, in view of the forthcoming in vivo irradiation of healthy and transgenic AD mouse models.</p>\u0000 </section>\u0000 \u0000 <section>\u0000 \u0000 <h3> Methods</h3>\u0000 <p>Monte Carlo simulations were carried out with the MCNP6 code to test different irradiation positions and study the least toxic treatment possible by modeling neutron shielding to preserve healthy tissue. A shielding prototype was built and tested by means of neutron activation measurements. A geometrical mouse model was developed with the aim of computing the dose-rates induced in each radiosensitive organ and thus to estimate possible irradiation times for future in vivo experiments.</p>\u0000 </section>\u0000 \u0000 <section>\u0000 \u0000 <h3> Results</h3>\u0000 <p>The computational study showed that the safest irradiation condition involves placing the shielding 20 cm from the TC entrance and that the best performing shielding material is <span></span><math>\u0000 <semantics>\u0000 <mrow>\u0000 <msup>\u0000 <mrow></mrow>\u0000 <mn>6</mn>\u0000 </msup>\u0000 <mi>Li</mi>\u0000 </mrow>\u0000 <annotation>$^{6}{rm Li}$</annotation>\u0000 </semantics></math> enriched lithium carbonate. Furthermore, taking into account the tolerance doses of each organ, the maximum animal irradiation time in an AD context is 45 min. The proposed set-up could also be used for preclinical studies on brain tumors; in this context, the maximum estimated irradiation time is 11 min.</p>\u0000 </section>\u0000 ","PeriodicalId":18384,"journal":{"name":"Medical physics","volume":"52 9","pages":""},"PeriodicalIF":3.2,"publicationDate":"2025-09-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://aapm.onlinelibrary.wiley.com/doi/epdf/10.1002/mp.18062","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144927363","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"医学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"A 3D verification system using dual-energy cone-beam CT with background subtraction and correction for x-ray CT-based polymer gel dosimetry","authors":"Kazuya Seki, Kanta Inoue, Shingo Ohira, Riki Oshika, Rie Tachibana, Ai Nakaoka, Hidenobu Tachibana","doi":"10.1002/mp.18074","DOIUrl":"https://doi.org/10.1002/mp.18074","url":null,"abstract":"<div>\u0000 \u0000 \u0000 <section>\u0000 \u0000 <h3> Background</h3>\u0000 \u0000 <p>Magnetic resonance imaging of polymer gel dosimeters remains the de facto standard to obtain high-quality dose information. However, magnetic resonance imaging scanner access is limited and scan times are long. x-Ray computed tomography-based polymer gel dosimeters (XCT-PGDs) offer convenience owing to easier access to CT scanners, especially cone-beam CT (CBCT) scanners integrated with linear accelerators, although they suffer from low dose resolution and high noise sensitivity. Conventional methods use multiple scans to enhance the contrast-to-noise ratio (CNR), which is time-intensive. Dual-energy CT provides a higher CNR, while dual-energy CBCT (DECBCT) reduces the required scan sets and improves CNR more efficiently, making it a valuable option for accurate XCT-PGD dose verification.</p>\u0000 </section>\u0000 \u0000 <section>\u0000 \u0000 <h3> Purpose</h3>\u0000 \u0000 <p>To investigate the effectiveness of DECBCT and a background correction and subtraction (BCS) method, which was newly developed for minimizing background variations across CBCT scans, in improving the dosimetric accuracy and efficiency of three-dimensional dose distribution verification systems using XCT-PGDs.</p>\u0000 </section>\u0000 \u0000 <section>\u0000 \u0000 <h3> Methods</h3>\u0000 \u0000 <p>Three types of plans were created to compare DECBCT combined with BCS against conventional image averaging: mock C-shape volumetric modulated arc therapy, mock multi-target stereotactic radiosurgery, and clinically delivered single-target stereotactic radiosurgery plans. XCT-PGD readout involved pre- and post-irradiation CBCT scans on a linear accelerator at 80 and 140 kV. First, the acquired image sets were processed using the BCS method to subtract background noise, which involved aligning background levels across pre- and post-irradiation scans to minimize variations. Second, the processed image sets were used to generate virtual monochromatic images (VMIs) with DECBCT by applying variable weighting factors. Simple background subtraction (BS) and averaging were also used for the comparative analysis. Dose difference (DD) and gamma analyses were performed with criteria of 3% and 3%/2 mm, respectively.</p>\u0000 </section>\u0000 \u0000 <section>\u0000 \u0000 <h3> Results</h3>\u0000 \u0000 <p>Compared with conventional BS, the BCS method improved the mean gamma pass rate across image types, with increases of 2.8%, 7.5%, and 10.4% for mock C-shape volumetric modulated arc therapy, mock multi-target stereotactic radiosurgery, and clinically delivered single-target stereotactic radiosurgery plans, respectively. Among the variable weighting factors ranging from −0.5 to 1.5, VMI with the optimal weighting factor of 0.5 provided the highest DD pass rate, althoug","PeriodicalId":18384,"journal":{"name":"Medical physics","volume":"52 9","pages":""},"PeriodicalIF":3.2,"publicationDate":"2025-09-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144927523","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"医学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Experimental validation of coarse ridge filters for FLASH proton therapy","authors":"Lucian Hotoiu,&nbsp;Francois Vander Stappen,&nbsp;Arnaud Pin,&nbsp;Rasmus Nilsson,&nbsp;Justin Ivoc,&nbsp;Michele Kim,&nbsp;Eric Diffenderfer,&nbsp;Boon-Keng Kevin Teo,&nbsp;Rudi Labarbe","doi":"10.1002/mp.18044","DOIUrl":"https://doi.org/10.1002/mp.18044","url":null,"abstract":"<div>\u0000 \u0000 \u0000 <section>\u0000 \u0000 <h3> Background</h3>\u0000 \u0000 <p>To maximize the potential benefit of the FLASH sparing effect during treatment, normal tissue regions would ideally be irradiated only briefly, typically for a couple of hundred milliseconds. Achieving such fast proton irradiation involves a mono-energetic beam at the highest cyclotron energy and the use of 3D-printed conformal energy modulators (CEM). In ConformalFLASH, a dedicated snout is mounted on the nozzle, containing the CEM, a range shifter, and an aperture.</p>\u0000 </section>\u0000 \u0000 <section>\u0000 \u0000 <h3> Purpose</h3>\u0000 \u0000 <p>Demonstrate that ConformalFLASH irradiation using a coarse 3D-printed CEM, defined by a geometry with spike resolution &gt; 0.5 mm in any dimension, is fulfilling existing clinical dose standards. The CEM is robust to printing errors and can be reliably manufactured with unmodified commercially available 3D printers.</p>\u0000 </section>\u0000 \u0000 <section>\u0000 \u0000 <h3> Methods</h3>\u0000 \u0000 <p>Monte-Carlo simulations were conducted to define the 3D-printing specifications of the CEM. A variety of CEMs were then printed according to specifications. CT scans were acquired, and in-beam measurements were performed for each part, using the FLASH beam properties, the FLASH snout, and dosimetry detectors.</p>\u0000 </section>\u0000 \u0000 <section>\u0000 \u0000 <h3> Results</h3>\u0000 \u0000 <p>Considering the proposed ConformaFLASH setup choice, it was possible to design coarse CEM that are both robust and easily printable using commercial technology. Over several measured cases, the 3D-printed CEM yields clinical-grade proton dose distributions. This confirms the irradiation set-up and the CEM manufacturing specifications as predefined through Monte Carlo simulations. CEM CT scans reinforce further the dosimetric results, to provide additional evidence of 3D printing quality.</p>\u0000 </section>\u0000 \u0000 <section>\u0000 \u0000 <h3> Conclusions</h3>\u0000 \u0000 <p>The dose distribution obtained through carefully specified CEM proves robust to production errors typically occurring in commercial 3D printing. The robustness opens the way to simplified manufacturing of relatively complex parts. Owing to the beam configuration, the snout, and the range shifter, the CEM was able to generate clinical-quality dose distributions. The integration of the FLASH snout with its elements on the nozzle of the proton therapy system represents an important step forward in comparison to existing state-of-the-art, facilitating easier preclinical and future clinical trial investigations.</p>\u0000 </section>\u0000 </div>","PeriodicalId":18384,"journal":{"name":"Medical physics","volume":"52 9","pages":""},"PeriodicalIF":3.2,"publicationDate":"2025-09-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144927387","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"医学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Development of dual-ended readout PET detectors achieving high 3D position resolution and high timing resolution using NINO and PICO2023 ASICs","authors":"Pengshuo Gan,&nbsp;Sen Yang,&nbsp;Haonan Li,&nbsp;Samuel Mungai,&nbsp;Zhonghua Kuang,&nbsp;Ning Ren,&nbsp;Yongfeng Yang,&nbsp;Zheng Liu","doi":"10.1002/mp.18072","DOIUrl":"https://doi.org/10.1002/mp.18072","url":null,"abstract":"&lt;div&gt;\u0000 \u0000 \u0000 &lt;section&gt;\u0000 \u0000 &lt;h3&gt; Background&lt;/h3&gt;\u0000 \u0000 &lt;p&gt;Time-of-flight (TOF) measurement in positron emission tomography (PET) scanner can significantly improve the signal-to-noise ratio of images. Despite the significant improvements of the timing resolution of PET detectors in recent years, further development is urgently needed.&lt;/p&gt;\u0000 &lt;/section&gt;\u0000 \u0000 &lt;section&gt;\u0000 \u0000 &lt;h3&gt; Purpose&lt;/h3&gt;\u0000 \u0000 &lt;p&gt;This work aims to develop a PET detector with high 3D position resolution and excellent timing resolution by using two high timing performance ASICs for whole-body and organ-specific TOF PET scanners.&lt;/p&gt;\u0000 &lt;/section&gt;\u0000 \u0000 &lt;section&gt;\u0000 \u0000 &lt;h3&gt; Methods&lt;/h3&gt;\u0000 \u0000 &lt;p&gt;PET detector consisting of an 8 × 8 LYSO crystal array with a crystal size of 1.45 &lt;span&gt;&lt;/span&gt;&lt;math&gt;\u0000 &lt;semantics&gt;\u0000 &lt;mo&gt;×&lt;/mo&gt;\u0000 &lt;annotation&gt;$ times $&lt;/annotation&gt;\u0000 &lt;/semantics&gt;&lt;/math&gt; 1.45 &lt;span&gt;&lt;/span&gt;&lt;math&gt;\u0000 &lt;semantics&gt;\u0000 &lt;mo&gt;×&lt;/mo&gt;\u0000 &lt;annotation&gt;$ times $&lt;/annotation&gt;\u0000 &lt;/semantics&gt;&lt;/math&gt; 20 mm&lt;sup&gt;3&lt;/sup&gt; dual-ended read out by 4 &lt;span&gt;&lt;/span&gt;&lt;math&gt;\u0000 &lt;semantics&gt;\u0000 &lt;mo&gt;×&lt;/mo&gt;\u0000 &lt;annotation&gt;$ times $&lt;/annotation&gt;\u0000 &lt;/semantics&gt;&lt;/math&gt; 4 SiPM arrays with an active pixel area of 3 &lt;span&gt;&lt;/span&gt;&lt;math&gt;\u0000 &lt;semantics&gt;\u0000 &lt;mo&gt;×&lt;/mo&gt;\u0000 &lt;annotation&gt;$ times $&lt;/annotation&gt;\u0000 &lt;/semantics&gt;&lt;/math&gt; 3 mm&lt;sup&gt;2&lt;/sup&gt; are measured in this work. The signals of the SiPM arrays are read out and processed separately for the timing and energy, with the energy signals multiplexed by row or column summing circuits to generate only 2 position encoding energy signals for each SiPM array and the timing signals processed by the NINO and PICO2023 ASICs to obtain a high precision timing information.&lt;/p&gt;\u0000 &lt;/section&gt;\u0000 \u0000 &lt;section&gt;\u0000 \u0000 &lt;h3&gt; Result&lt;/h3&gt;\u0000 \u0000 &lt;p&gt;The detector achieved a flood histogram with all crystals clearly resolved, an average energy resolution of 10.7% and depth of interaction (DOI) resolution of 2.4 mm. The coincidence timing resolutions (CTR) of the detector achieved with the NINO and PICO2023 ASICs were 149 &lt;span&gt;&lt;/span&gt;&lt;math&gt;\u0000 &lt;semantics&gt;\u0000 &lt;mo&gt;±&lt;/mo&gt;\u0000 &lt;annotation&gt;$pm $&lt;/annotation&gt;\u0000 &lt;/semantics&gt;&lt;/math&gt; 3 ps and 142 &lt;span&gt;&lt;/span&gt;&lt;math&gt;\u0000 &lt;semantics&gt;\u0000 &lt;mo&gt;±&lt;/mo&gt;\u0000 &lt;annotation&gt;$pm $&lt;/annotation&gt;\u0000 &lt;/semantics&gt;&lt;/math&gt; 3 ps, respectively, if both SiPM arrays were used to measure the timing and the depth dependence of timing correction","PeriodicalId":18384,"journal":{"name":"Medical physics","volume":"52 9","pages":""},"PeriodicalIF":3.2,"publicationDate":"2025-08-24","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144894329","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"医学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"High scattering sensitivity entropy imaging for breast tumor characterization and classification","authors":"Xinyu Zhang,&nbsp;Yang Gu,&nbsp;Dan Zhao,&nbsp;Yang Jiao,&nbsp;Fenglin Dong,&nbsp;Yaoyao Cui","doi":"10.1002/mp.18063","DOIUrl":"https://doi.org/10.1002/mp.18063","url":null,"abstract":"&lt;div&gt;\u0000 \u0000 \u0000 &lt;section&gt;\u0000 \u0000 &lt;h3&gt; Background&lt;/h3&gt;\u0000 \u0000 &lt;p&gt;Diagnosing and characterizing breast lesions and tumors remains a common challenge in clinical practice. Ultrasound imaging stands out for its safety, real-time capability, and affordability. However, the image quality of conventional ultrasound examination is limited, and the diagnosis of ultrasonographic images depends heavily on the experience of the sonographer. Therefore, improving ultrasound images and extracting tissue information from ultrasound signals to provide auxiliary means is crucial for accurate breast tumor diagnosis.&lt;/p&gt;\u0000 &lt;/section&gt;\u0000 \u0000 &lt;section&gt;\u0000 \u0000 &lt;h3&gt; Purpose&lt;/h3&gt;\u0000 \u0000 &lt;p&gt;Medical ultrasound imaging has been widely used in clinical diagnosis. However, traditional ultrasound has limitations in the diagnosis of breast soft tissue diseases. This study proposed a high scattering sensitivity fuzzy entropy (FE) imaging method to enhance image contrast and improve detectability for breast tumors. Moreover, this imaging method can make a preliminary classification and characterization of benign and malignant breast lesions through quantitative analysis of ultrasound radio frequency data and the calculation of the entropy value without biopsy examination.&lt;/p&gt;\u0000 &lt;/section&gt;\u0000 \u0000 &lt;section&gt;\u0000 \u0000 &lt;h3&gt; Methods&lt;/h3&gt;\u0000 \u0000 &lt;p&gt;To achieve the fuzzy entropy imaging, a sliding window is selected to traverse across the image with a step of one sampling point while the entropy value within the sliding window is calculated. This entropy value is assigned to the center pixel of the window. The parametric image was obtained after the entropy values of all pixels were calculated. During the clinical experiments, the breast lesions were classified as benign or malignant by biopsy examination. After entropy imaging, the average entropy value of the lesion area was calculated. The entropy values of all cases of benign and malignant tumors were averaged, respectively, to verify whether the fuzzy entropy can characterize the breast lesions. All the statistical analysis was conducted by one-sample t-test to obtain the mean value and standard deviation. The Tukey test was performed, and the effect size of Cohen's d was calculated to verify whether there was a significant difference between the entropy value of benign lesions and malignant lesions.&lt;/p&gt;\u0000 &lt;/section&gt;\u0000 \u0000 &lt;section&gt;\u0000 \u0000 &lt;h3&gt; Results&lt;/h3&gt;\u0000 \u0000 &lt;p&gt;In the clinical breast imaging experiment, the FE method obtained the highest Matthews correlation coefficient (MCC) of 0.875 ± 0.047 (&lt;i&gt;p&lt;/i&gt; &lt; 0.0001) and F1 score of 0.876 ± 0.049 (&lt;i&gt;p&lt;/i&gt; &lt; 0.0001). The MCC and F1 scores of FE imaging were significantly different from those of other entropy imaging methods in the Tukey test (&lt;i&gt;p&lt;/i&gt; &","PeriodicalId":18384,"journal":{"name":"Medical physics","volume":"52 9","pages":""},"PeriodicalIF":3.2,"publicationDate":"2025-08-24","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144894335","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"医学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Operational efficiency and clinical safety of laser positioning-assisted CT-guided lung nodule biopsy: A single-center retrospective cohort study","authors":"Guoqiang Liu,&nbsp;Shulin Chen,&nbsp;Qingfeng Deng,&nbsp;Jianhua Wang,&nbsp;Guoqing Qiao","doi":"10.1002/mp.18066","DOIUrl":"https://doi.org/10.1002/mp.18066","url":null,"abstract":"<div>\u0000 \u0000 \u0000 <section>\u0000 \u0000 <h3> Background</h3>\u0000 \u0000 <p>CT-guided percutaneous lung nodule biopsy (CLNB) is a critical diagnostic tool for pulmonary lesions, yet traditional methods are limited by operator-dependent variability and higher complication risks. The dual-laser beam design of the laser positioning (LP) device, utilizing real-time trajectory correction, holds potential to improve puncture accuracy and reduce human error, but its clinical value in CLNB remains to be systematically validated.</p>\u0000 </section>\u0000 \u0000 <section>\u0000 \u0000 <h3> Background</h3>\u0000 \u0000 <p>The purpose of this study was to retrospectively assess the advanced puncture efficacy and clinical safety of the LP device during CLNB.</p>\u0000 </section>\u0000 \u0000 <section>\u0000 \u0000 <h3> Methods</h3>\u0000 \u0000 <p>A total of 115 patients (61±12 [SD]years; 83 women) were included in this study. All patients were allocated into two groups: one group underwent CLNB without an LP device, while the other group used an LP device during the procedure. The efficacy of the procedures was assessed based on the success rate, the adjustments number and the puncture time. Additionally, safety evaluations focused on complications associated with the percutaneous surgery.</p>\u0000 </section>\u0000 \u0000 <section>\u0000 \u0000 <h3> Results</h3>\u0000 \u0000 <p>The success rate of the first puncture in the LP group was significantly higher than in the CLNB group [88.70%(55/62) vs. 52.80%(28/53), <i>p</i> &lt; 0.001]. The puncture time was significantly lower in the LP group (9.71±4.20 vs. 18.21±6.53 min, <i>p</i> &lt; 0.001). When analyzing the skin-to-lesion distance, categorized into two ranges of 20–60 mm and &gt; 60 mm, the LP group consistently required less time for the procedure (9.66±5.20 vs. 16.86±5.16 min, <i>p</i> &lt; 0.001), (9.93±3.97 vs. 19.31±7.39 min, <i>p</i> &lt; 0.001). Furthermore, the incidence of complications in the LP group was significantly lower than in the CLNB group [6.45% (4/62) vs. 50.94% (27/53), <i>p</i> &lt; 0.001].</p>\u0000 </section>\u0000 \u0000 <section>\u0000 \u0000 <h3> Conclusions</h3>\u0000 \u0000 <p>The LP device improved the puncture accuracy of CLNB, shortened the operation time, and reduced the incidence of complications.</p>\u0000 </section>\u0000 </div>","PeriodicalId":18384,"journal":{"name":"Medical physics","volume":"52 9","pages":""},"PeriodicalIF":3.2,"publicationDate":"2025-08-24","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144894337","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"医学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Complexity-based unsupervised machine learning for patient-specific VMAT quality assurance","authors":"Savino Cilla,&nbsp;Carmela Romano,&nbsp;Pietro Viola,&nbsp;Maurizio Craus,&nbsp;Gabriella Macchia,&nbsp;Francesco Deodato,&nbsp;Alessio G. Morganti","doi":"10.1002/mp.18013","DOIUrl":"https://doi.org/10.1002/mp.18013","url":null,"abstract":"&lt;div&gt;\u0000 \u0000 \u0000 &lt;section&gt;\u0000 \u0000 &lt;h3&gt; Background&lt;/h3&gt;\u0000 \u0000 &lt;p&gt;Patient-specific quality assurance (PSQA) is essential to guarantee the requested accuracy and safety of high-precision radiotherapy treatments. With the widespread adoption of modulated-intensity techniques, there is a growing need for increased operational efficiency. The potential of machine learning (ML) to accurately predict PSQA results has been investigated in recent years. In particular, plan complexity metrics have been used as model input features to be related to the PSQA outcome results in a number of supervised ML models. However, an unsupervised cluster analysis, able to uncover hidden patterns or groupings in data, has not been yet performed.&lt;/p&gt;\u0000 &lt;/section&gt;\u0000 \u0000 &lt;section&gt;\u0000 \u0000 &lt;h3&gt; Purpose&lt;/h3&gt;\u0000 \u0000 &lt;p&gt;The primary aim of this research was to investigate the potential of different unsupervised ML methods to unravel hidden patterns and groupings in PSQA data based on a clustering analysis of plan complexity.&lt;/p&gt;\u0000 &lt;/section&gt;\u0000 \u0000 &lt;section&gt;\u0000 \u0000 &lt;h3&gt; Methods and materials&lt;/h3&gt;\u0000 \u0000 &lt;p&gt;A total of 1329 pretreatment verification data from 660 consecutive patients with different tumour sites treated using volumetric modulated arc therapy (VMAT) were analyzed using the modulation complexity score (MCS) and the dynamic log-files generated by the linac. Predicted and measured fluences were compared using γ-analysis in terms of mean γ-values (γ&lt;sub&gt;mean&lt;/sub&gt;) and γ-pass rate (γ&lt;sub&gt;%&lt;/sub&gt;) at the 2%(local)/2 mm criterion. Three unsupervised clustering algorithms, including agglomerative hierarchical clustering (AHC), K-means (KM) and Gaussian mixture models (GMM), were implemented to investigate the existence of natural groupings or clusters based on plan complexity. In addition, we subsequently trained several supervised models to validate cluster assignments on an external cohort of 202 VMAT arcs.&lt;/p&gt;\u0000 &lt;/section&gt;\u0000 \u0000 &lt;section&gt;\u0000 \u0000 &lt;h3&gt; Results&lt;/h3&gt;\u0000 \u0000 &lt;p&gt;For each clustering algorithms, the silhouette scores and the dendrogram analysis indicate the optimal number of clusters is three. The GMM clustered 65 arcs (4.9% of total arcs) into cluster 1 with mean values of γ&lt;sub&gt;%&lt;/sub&gt;, γ&lt;sub&gt;mean&lt;/sub&gt; and MCS of 76.7%, 0.85 and 0.112, respectively. 916 arcs (68.9% of total arcs) were grouped into cluster 2 with mean values of γ&lt;sub&gt;%&lt;/sub&gt;, γ&lt;sub&gt;mean&lt;/sub&gt; and MCS of 86.5%, 0.58 and 0.209, respectively. Lastly, 348 arcs (26.2% of total arcs) were grouped into cluster 3 with mean values of γ&lt;sub&gt;%&lt;/sub&gt;, γ&lt;sub&gt;mean&lt;/sub&gt; and MCS of 92.9%, 0.40 and 0.359, respectively. Cluster 1 was associated with overmodulated plans, providing a warning MCS cutoff value of 0.145 for prompt replanning. Similarly, cluster 3 was associated with PSQA o","PeriodicalId":18384,"journal":{"name":"Medical physics","volume":"52 9","pages":""},"PeriodicalIF":3.2,"publicationDate":"2025-08-24","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144894349","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"医学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"A dual-domain regularization method for ring artifact removal of X-ray CT","authors":"Xin Lu,&nbsp;Hongyang Zhu,&nbsp;Yanwei Qin,&nbsp;Xinran Yu,&nbsp;Tianjiao Sun,&nbsp;Yunsong Zhao","doi":"10.1002/mp.18065","DOIUrl":"https://doi.org/10.1002/mp.18065","url":null,"abstract":"<div>\u0000 \u0000 \u0000 <section>\u0000 \u0000 <h3> Background</h3>\u0000 \u0000 <p>Photon-counting detectors (PCDs) offer improved spatial resolution and dose efficiency. However, as a new X-ray detection device, PCD faces technical challenges, particularly the non-uniformity among detector units, which can lead to ring artifacts in reconstructed CT images.</p>\u0000 </section>\u0000 \u0000 <section>\u0000 \u0000 <h3> Purpose</h3>\u0000 \u0000 <p>To address this challenge, we propose a dual-domain regularization model to effectively remove ring artifacts while maintaining the integrity of the original CT image.</p>\u0000 </section>\u0000 \u0000 <section>\u0000 \u0000 <h3> Methods</h3>\u0000 \u0000 <p>The proposed model corrects the vertical stripe artifacts on the sinogram by innovatively updating the response inconsistency compensation coefficients of detector units, which is achieved by employing the group sparse constraint and the projection-view direction sparse constraint on the stripe artifacts. Simultaneously, we apply the sparse constraint on the reconstructed image to further rectify ring artifacts in the image domain. The key advantage of the proposed method lies in considering the relationship between the response inconsistency compensation coefficients of the detector units and the projection views, which enables a more accurate correction of the response of the detector units. An alternating minimization method is designed to solve the model.</p>\u0000 </section>\u0000 \u0000 <section>\u0000 \u0000 <h3> Results</h3>\u0000 \u0000 <p>Comparative experiments on simulated data and real PCD data demonstrate that the proposed method outperforms existing correction methods in artifact suppression while better preserving structural details.</p>\u0000 </section>\u0000 \u0000 <section>\u0000 \u0000 <h3> Conclusions</h3>\u0000 \u0000 <p>The proposed method can effectively mitigate ring artifacts in PCD-reconstructed CT images while preserving details, thereby enhancing image quality and improving the reliability of clinical diagnosis.</p>\u0000 </section>\u0000 </div>","PeriodicalId":18384,"journal":{"name":"Medical physics","volume":"52 9","pages":""},"PeriodicalIF":3.2,"publicationDate":"2025-08-24","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144894334","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"医学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"An innovative process for efficient automated optimizing IMRT knowledge-based planning (KBP)","authors":"Ali Yousefi,&nbsp;Saeedeh Ketabi,&nbsp;Amy C. Moreno,&nbsp;Iraj Abedi,&nbsp;Yusung Kim,&nbsp;Somayeh Gholami","doi":"10.1002/mp.18055","DOIUrl":"https://doi.org/10.1002/mp.18055","url":null,"abstract":"&lt;div&gt;\u0000 \u0000 \u0000 &lt;section&gt;\u0000 \u0000 &lt;h3&gt; Background&lt;/h3&gt;\u0000 \u0000 &lt;p&gt;Radiotherapy treatment planning is a time-consuming task that requires expert and skilled manpower, particularly for weight adjustment. Valuable attempts have been made to automate the treatment planning process as well as decrease computation time in recent years. Artificial intelligence tools and a knowledge-based planning (KBP) approach have played considerable roles in this regard. However, this area also requires more precise and smart approaches.&lt;/p&gt;\u0000 &lt;/section&gt;\u0000 \u0000 &lt;section&gt;\u0000 \u0000 &lt;h3&gt; Purpose&lt;/h3&gt;\u0000 \u0000 &lt;p&gt;The current study aims to advance KBP in two practical and impactful areas. First, it presents a novel approach to automate IMRT treatment planning using a mathematical optimization framework. Second, it proposes two innovative downsizing techniques designed to enhance computational efficiency and significantly reduce solving time, while evaluating their performance in terms of both treatment plan quality and time savings in an integrated manner.&lt;/p&gt;\u0000 &lt;/section&gt;\u0000 \u0000 &lt;section&gt;\u0000 \u0000 &lt;h3&gt; Methods&lt;/h3&gt;\u0000 \u0000 &lt;p&gt;Two mathematical models were applied: QuadLin for treatment plan optimization and its revised model for automatically adjusting the weights of the QuadLin objective function. The study emphasizes improving computational efficiency and reducing solving time by introducing an innovative algorithm, called SVSIDB, which clusters voxels based on the dominant beamlet concept. Additionally, the hybrid ultra-heuristic ABC-K-Means technique was developed for voxel clustering. All models and techniques have been run on the data of 30 patients with head and neck cancer from a recently published real dataset, Open-KBP. Problems were solved in the CVX framework, with commercial solver Mosek, as well as programming in MATLAB. The results have been evaluated by both plan quality approach, satisfied clinical criteria, and computational efficiency, solving time reduction.&lt;/p&gt;\u0000 &lt;/section&gt;\u0000 \u0000 &lt;section&gt;\u0000 \u0000 &lt;h3&gt; Results&lt;/h3&gt;\u0000 \u0000 &lt;p&gt;The weights of the QuadLin objective function were automatically adjusted using the mathematical framework. Although the Auto-Imputed weights differed significantly from the manually assigned ones, the resulting plans showed no substantial differences in terms of plan quality. Automatic treatment plans improved satisfied clinical criteria by an average of over 21%, 15%, and at least 13% compared to the predicted dose, the reference plan, and previous research, respectively. Additionally, SVSIDB presented a systematic voxel clustering method that reduces solving time by approximately 50% compared to full-data models, while maintaining treatment plan quality. SVSIDB achieved an 81.3% clinical criteria satisfaction in","PeriodicalId":18384,"journal":{"name":"Medical physics","volume":"52 9","pages":""},"PeriodicalIF":3.2,"publicationDate":"2025-08-24","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144894336","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"医学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Development and demonstration of end-to-end testing for intra-fraction motion-managed workflows","authors":"Stijn Oolbekkink,&nbsp;Jochem W. H. Wolthaus,&nbsp;Bram van Asselen,&nbsp;Peter R. S. Stijnman,&nbsp;Bas W. Raaymakers","doi":"10.1002/mp.18042","DOIUrl":"https://doi.org/10.1002/mp.18042","url":null,"abstract":"&lt;div&gt;\u0000 \u0000 \u0000 &lt;section&gt;\u0000 \u0000 &lt;h3&gt; Background&lt;/h3&gt;\u0000 \u0000 &lt;p&gt;Intra-fraction motion management techniques, including beam gating and intra-fraction drift correction (IDC), have recently been introduced on the Unity MR-linac (Elekta AB, Stockholm, Sweden) to mitigate the dosimetric impact of motion during treatment. However, residual motion (e.g., within the gating window) still affects the delivered dose, causing deviations from the statically planned dose. Conventional end-to-end (E2E) testing does not incorporate such (known) motion, hampering evaluation of motion managed workflows.&lt;/p&gt;\u0000 &lt;/section&gt;\u0000 \u0000 &lt;section&gt;\u0000 \u0000 &lt;h3&gt; Purpose&lt;/h3&gt;\u0000 \u0000 &lt;p&gt;This study develops and demonstrates novel methods that incorporate known motion before treatment delivery. Using such a reference dose distribution allows for E2E testing of intra-fraction motion-managed workflows.&lt;/p&gt;\u0000 &lt;/section&gt;\u0000 \u0000 &lt;section&gt;\u0000 \u0000 &lt;h3&gt; Methods&lt;/h3&gt;\u0000 \u0000 &lt;p&gt;A novel approach was developed to assess the E2E accuracy for motion-managed delivery techniques by comparing the measured dose distribution to a reference dose distribution that incorporates the applied motion during the delivery. Two motion-included reference dose distributions were generated and evaluated: (1) A Priori Motion-Included (APriMI) dose distribution which uses the known (periodic) motion to estimate the influence of anatomical motion on the dose distribution, and incorporates this into a new dose distribution; and (2) the Posteriori Motion-Included (PostMI) dose distribution, which adds an external trigger to relate the beam-on/off time to the motion of the setup. This allows for evaluation of non-periodic motion, or a drift motion during IDC workflows. In addition to these, the conventionally used static treatment planning system (TPS) dose distribution was used as a reference dose distribution.&lt;/p&gt;\u0000 \u0000 &lt;p&gt;Several scenarios were evaluated: static (no phantom motion), two unmanaged, and two motion-managed scenarios using the Comprehensive Motion Management (CMM) software (Elekta AB, Stockholm, Sweden) for gated and IDC workflows, with &lt;span&gt;&lt;/span&gt;&lt;math&gt;\u0000 &lt;semantics&gt;\u0000 &lt;msup&gt;\u0000 &lt;mi&gt;cos&lt;/mi&gt;\u0000 &lt;mn&gt;4&lt;/mn&gt;\u0000 &lt;/msup&gt;\u0000 &lt;annotation&gt;$mathrm{cos^4}$&lt;/annotation&gt;\u0000 &lt;/semantics&gt;&lt;/math&gt; and linear drift motion patterns. All measurements were performed on a clinical Unity MR-linac equipped with CMM software, using film dosimeters for high spatial resolution dose distribution assessment. The geometric and dosimetric E2E accuracy of the workflow were evaluated for all scenarios.&lt;/p&gt;\u0000 &lt;/section","PeriodicalId":18384,"journal":{"name":"Medical physics","volume":"52 9","pages":""},"PeriodicalIF":3.2,"publicationDate":"2025-08-24","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://aapm.onlinelibrary.wiley.com/doi/epdf/10.1002/mp.18042","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144894338","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"医学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}