Physics in medicine and biology最新文献

{"title":"A systematic characterization of plastic scintillation dosimeters response in magnetic fields: I. Experimental measurements.","authors":"Yunuen Cervantes, Simon Lambert-Girard, Ilias Billas, François Therriault-Proulx, Hugo Bouchard, Louis Archambault, Luc Beaulieu","doi":"10.1088/1361-6560/add1a7","DOIUrl":"https://doi.org/10.1088/1361-6560/add1a7","url":null,"abstract":"<p><p><i>Objective.</i>This study aims to evaluate the performance of five distinct plastic scintillation dosimeters (PSDs) in magnetic fields, as well as to validate the accuracy of the hyperspectral approach for stem-effect correction. The effect of the magnetic field on different base core materials and components within the PSDs was also investigated, as well as the effect of field size and orientation.<i>Approach.</i>Each PSD was placed at 5 cm depth in a water tank inside an electromagnet gap. Magnetic fields, between 0 and 1.5 T, were set to be perpendicular to the 6 MeV photon beam and to the PSD axis. The detector axis was either parallel or perpendicular to the photon beam. Different field sizes were used. The hyperspectral technique was validated and used to determine the scintillation, fluorescence and Cherenkov components at different magnetic fields.<i>Main results.</i>The hyperspectral method accurately removes stem effects in magnetic fields, even when calibration is performed at 0 T. The stem light yield shows good agreement with clear fiber measurements, with relative differences within 2.0%. In the parallel orientation, the corrected PSD response is highly symmetric relative to magnetic field polarity, with a maximum variation of only 0.2% from unity. Scintillation light yield increases with magnetic field by 3.6%-6.25% depending on PSD properties. Cherenkov light yield varies up to 230% and down to 0.30% of the 0 T value, depending on magnetic field polarity. The impact of magnetic fields depends primarily on the properties of the scintillator itself, with polyvinyltoluene-based probes showing greater sensitivity than polystyrene-based probes. The inclusion of a wavelength shifter has minimal on the magnetic field's effect on scintillation light yield. Normalized scintillation light yield decreases with smaller field sizes.<i>Significance.</i>PSDs are well-suited for accurate dosimetry in magnetic fields, provided that accurate stem-effect correction techniques are applied. The scintillator properties play a significant role in determining the PSD's sensitivity to magnetic fields. The hyperspectral method is a robust approach for accurate stem-effect removal in such conditions.</p>","PeriodicalId":20185,"journal":{"name":"Physics in medicine and biology","volume":"70 10","pages":""},"PeriodicalIF":3.3,"publicationDate":"2025-05-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144050146","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"医学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Range uncertainty reductions in proton therapy and resulting improvements in quality-adjusted life expectancy (QALE) for head-and-neck cancer patients.","authors":"Sebastian Tattenberg, Peilin Liu, Anthony Mulhem, Xiaoda Cong, Christopher Thome, Cornelia Hoehr, Xuanfeng Ding","doi":"10.1088/1361-6560/add07d","DOIUrl":"https://doi.org/10.1088/1361-6560/add07d","url":null,"abstract":"<p><p><i>Objective</i>. Due to higher dose conformality to the target, proton radiotherapy for cancer has received rapidly-growing interest. However, uncertainties in the<i>in vivo</i>proton range and methods to reduce them remain active areas of research. Based on 20 patients with head-and-neck cancer, this study aims to quantify the benefits of proton range uncertainty reductions in terms of the resulting improvements in quality-adjusted life expectancy (QALE).<i>Approach</i>. For each patient, two different proton therapy treatment plans were created, which assumed a current clinical range uncertainty of approximately 3.5% (IMPT_3.5%) and a potentially achievable range uncertainty of 1.0% (IMPT_1%). A Markov model considering the probability of tumor control and the development of xerostomia, larynx edema, secondary cancer, and/or metastases as well as death from primary cancer, secondary cancer, metastases, or unrelated causes was constructed, and for every patient and treatment plan, 10 000 simulations of the patient's entire lifetime from the time of treatment until death were performed.<i>Main results.</i>A 3.5%-1% range uncertainty reduction increased QALE by up to 0.4 quality-adjusted life years (QALYs) in the nominal and up to 0.6 QALY in the worst-case scenario, equivalent to 4.8 months and 7.2 months of life in perfect health. This was largely the result of a reduction in healthy tissue toxicity rates, which were reduced by up to 8.5 percentage points (pp) and 10.0 pp in the nominal and worst-case scenario, respectively.<i>Significance</i>. The benefits of a 3.5%-1% range uncertainty reduction in 20 patients with head-and-neck cancer were quantified in terms of the associated improvement in QALE. The highest QALE improvements were observed in patients in the top quartile of youngest patients at the time of treatment, due to the longer potential lifespan over which prevented healthy tissue toxicities would have impacted the patients' quality of life.</p>","PeriodicalId":20185,"journal":{"name":"Physics in medicine and biology","volume":"70 10","pages":""},"PeriodicalIF":3.3,"publicationDate":"2025-05-06","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144015760","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"医学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"A novel transfer learning framework for non-uniform conductivity estimation with limited data in personalized brain stimulation.","authors":"Yoshiki Kubota, Sachiko Kodera, Akimasa Hirata","doi":"10.1088/1361-6560/add105","DOIUrl":"https://doi.org/10.1088/1361-6560/add105","url":null,"abstract":"<p><p><i>Objective</i>. Personalized transcranial magnetic stimulation (TMS) requires individualized head models that incorporate non-uniform conductivity to enable target-specific stimulation. Accurately estimating non-uniform conductivity in individualized head models remains a challenge due to the difficulty of obtaining precise ground truth data. To address this issue, we have developed a novel transfer learning-based approach for automatically estimating non-uniform conductivity in a human head model with limited data.<i>Approach</i>. The proposed method complements the limitations of the previous conductivity network (CondNet) and improves the conductivity estimation accuracy. This method generates a segmentation model from T1- and T2-weighted magnetic resonance images, which is then used for conductivity estimation via transfer learning. To enhance the model's representation capability, a Transformer was incorporated into the segmentation model, while the conductivity estimation model was designed using a combination of Attention Gates and Residual Connections, enabling efficient learning even with a small amount of data.<i>Main results</i>. The proposed method was evaluated using 1494 images, demonstrating a 2.4% improvement in segmentation accuracy and a 29.1% increase in conductivity estimation accuracy compared with CondNet. Furthermore, the proposed method achieved superior conductivity estimation accuracy even with only three training cases, outperforming CondNet, which was trained on an adequate number of cases. The conductivity maps generated by the proposed method yielded better results in brain electrical field simulations than CondNet.<i>Significance</i>. These findings demonstrate the high utility of the proposed method in brain electrical field simulations and suggest its potential applicability to other medical image analysis tasks and simulations.</p>","PeriodicalId":20185,"journal":{"name":"Physics in medicine and biology","volume":"70 10","pages":""},"PeriodicalIF":3.3,"publicationDate":"2025-05-06","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144037064","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"医学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"A Monte Carlo method for the quantitative analysis of triage algorithms in mass casualty events.","authors":"Tobias Schwerdtfeger, Lorenzo Brualla","doi":"10.1088/1361-6560/adcbfc","DOIUrl":"https://doi.org/10.1088/1361-6560/adcbfc","url":null,"abstract":"<p><p><i>Objective.</i>In mass casualty scenarios, efficient triage algorithms are used to prioritize medical care when resources are outnumbered by victims. This research proposes a computational approach to quantitatively analyze and optimize triage algorithms by developing a Monte Carlo code which is subsequently validated against the few quantitative data.<i>Approach</i>. The developed Monte Carlo code is used to simulate several mass casualty events, namely car accidents, burns, shootings, sinking ships and a human stampede. Four triage algorithms- modified simple triage and rapid treatment, primäres Ranking zur initialen Orientierung im Rettungsdienst, CareFlight, and field triage score (FTS)-are evaluated using metrics like mortality, overtriage, undertriage, sensitivity, and specificity.<i>Main results.</i>Results indicate that, on average, the analyzed algorithms achieve about 35% accuracy in classifying critical casualties when compared to a perfect algorithm, with FTS being the less accurate. However, when all casualties are considered, algorithm performance improves to around 63% of a perfect algorithm, except for FTS. The study identifies an increased probability of false positives for red categorization due to comorbidities and a higher tendency for false negatives in casualties with burns or internal trunk injuries.<i>Significance.</i>Despite variations in vital sign measurements, triage classification results do not depend on the measurement uncertainties of the paramedics. The ethically challenging decision, of withholding medical care from low-survival probability victims, leads to a 63% reduction in mortality among critical casualties. This research establishes a quantitative method for triage algorithm studies, highlighting their robustness to measurement uncertainties.</p>","PeriodicalId":20185,"journal":{"name":"Physics in medicine and biology","volume":"70 10","pages":""},"PeriodicalIF":3.3,"publicationDate":"2025-05-06","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144037962","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"医学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"ICRP pregnant-female mesh-type reference computational phantoms part 2: development of maternal phantoms.","authors":"Bangho Shin, Suhyeon Kim, Chansoo Choi, Hyeonil Kim, Yeon Soo Yeom, Beom Sun Chung, Thang Tat Nguyen, Wesley E Bolch, Sungho Moon, Haegin Han, Chan Hyeong Kim","doi":"10.1088/1361-6560/add07a","DOIUrl":"https://doi.org/10.1088/1361-6560/add07a","url":null,"abstract":"<p><p><i>Objective</i>. In the present study, the pregnant-female mesh-type reference computational phantoms (MRCPs) of the International Commission on Radiological Protection (ICRP) were fully developed in the tetrahedral-mesh format by constructing the maternal phantoms for 8-, 10-, 15-, 20-, 25-, 30-, 35-, and 38 week fetal ages.<i>Approach</i>. The reference blood-inclusive organ dataset (masses, elemental compositions, and densities) and the anthropometric data (rib cage dimensions, spinal curvature and pelvic inclination angle, breast dimensions, and anthropometric parameters) were established, which were then used to develop the maternal phantoms. During the development process, the pregnant-female MRCPs were fully developed by installing the mesh-type fetal phantoms in the maternal uterus considering the shape and position of the fetus.<i>Main results</i>. The dosimetric impact of the phantoms, in terms of fetal dose from maternal radionuclide intake, was investigated by calculating the photon specific absorbed fractions (SAFs) for some selected maternal organs as source regions and the entire fetal phantom as a target region. The results showed that the SAFs for the older fetus were larger than those for the younger fetus when the source-target distance is long, and the opposite trend is observed when the distance is short. These results were observed due to the growth of the fetus.<i>Significance</i>. The pregnant-female MRCPs will serve as the only ICRP reference phantoms representing the pregnant women and fetuses. The comprehensive SAFs dataset will be computed to calculate the ICRP reference dose coefficients for fetal members of the public.</p>","PeriodicalId":20185,"journal":{"name":"Physics in medicine and biology","volume":"70 9","pages":""},"PeriodicalIF":3.3,"publicationDate":"2025-05-02","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144037772","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"医学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Diagnosis assistant for liver cancer utilizing a large language model with three types of knowledge.","authors":"Xuzhou Wu, Guangxin Li, Xing Wang, Zeyu Xu, Yingni Wang, Shuge Lei, Jianming Xian, Xueyu Wang, Yibao Zhang, Gong Li, Kehong Yuan","doi":"10.1088/1361-6560/adcb17","DOIUrl":"10.1088/1361-6560/adcb17","url":null,"abstract":"<p><p><i>Objective.</i>Liver cancer has a high incidence rate, but experienced doctors are lacking in primary healthcare settings. The development of large models offers new possibilities for diagnosis. However, in liver cancer diagnosis, large models face certain limitations, such as insufficient understanding of specific medical images, inadequate consideration of liver vessel factors, and inaccuracies in reasoning logic. Therefore, this study proposes a diagnostic assistance tool specific to liver cancer to enhance the diagnostic capabilities of primary care doctors.<i>Approach.</i>A liver cancer diagnosis framework combining large and small models is proposed. A more accurate model for liver tumor segmentation and a more precise model for liver vessel segmentation are developed. The features extracted from the segmentation results of the small models are combined with the patient's medical records and then provided to the large model. The large model employs chain of thought prompts to simulate expert diagnostic reasoning and uses Retrieval-Augmented Generation to provide reliable answers based on trusted medical knowledge and cases.<i>Main results.</i>In the small model part, the proposed liver tumor and liver vessel segmentation methods achieve improved performance. In the large model part, this approach receives higher evaluation scores from doctors when analyzing patient imaging and medical records.<i>Significance.</i>First, a diagnostic framework combining small models and large models is proposed to optimize the liver cancer diagnosis process. Second, two segmentation models are introduced to compensate for the large model's shortcomings in extracting semantic information from images. Third, by simulating doctors' reasoning and integrating trusted knowledge, the framework enhances the reliability and interpretability of the large model's responses while reducing hallucination phenomena.</p>","PeriodicalId":20185,"journal":{"name":"Physics in medicine and biology","volume":"70 9","pages":""},"PeriodicalIF":3.3,"publicationDate":"2025-05-02","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143988627","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"医学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Beam modeling and validation for a 1.5 T MR-linac in an alternative treatment planning system.","authors":"Roel G J Kierkels, Guido C Hilgers, Agnes Angerud, Claes Fälth, André Minken","doi":"10.1088/1361-6560/adcfed","DOIUrl":"https://doi.org/10.1088/1361-6560/adcfed","url":null,"abstract":"<p><p><i>Objective.</i>MR-guided adaptive radiotherapy (MRgART) is ideally suited to adjust the treatment plan for anatomical changes. The online nature of MRgART involves multiple process steps during each treatment fraction, which may greatly benefit from automation. TheRayStationtreatment planning system incorporates automation features by design, but requires dose calculations in the presence of an external magnetic field and the modeling of the MRgART system. This study developed and commissioned a comprehensive model for the 1.5 T MR-guided linear accelerators (MR-linacs) inRayStation.<i>Approach.</i>MR-linac dose profiles and output factors were used to model the Unity MR-linac inRayStation. The MR cryostat was implemented in the Monte Carlo simulation as a multi-layer barrel, adjusted using simulations and in-air output measurements. The cryostat transmission variation with gantry angle was added as a fluence correction. Dose distributions of on-axis square, off-axis square, and 90 IMRT fields of ten prostate MR-linac treatment plans were evaluated with the PTW Octavius 1500MR detector array. The radiofrequency coils and couch were characterized with megavoltage imager transmission measurements. CT scans of the coils were used to model its geometry inRayStationand mass densities were assigned to match the measured attenuation.<i>Results.</i>Differences between measured and calculated depth dose showed a<i>γ</i>< 0.5 beyond<i>d</i>_max. For both the inline and crossline profiles, the<i>γ</i>evaluation exhibited a<i>γ</i>< 1.0 for nearly all evaluated points. The maximum difference between the measured and calculated cryostat scatter was 0.6%. The average<i>γ</i>pass rate for the on-axis, off-axis, and IMRT fields was >98.3% (range: 91.2%-100%). The average coil transmissions were 0.6 (anterior) and 2.2% (posterior).<i>Significance.</i>We successfully modeled and commissioned the 1.5 T MR-linac inRayStationwell within tolerance limits as specified by the American Association of Physicists in Medicine TG-157 report.</p>","PeriodicalId":20185,"journal":{"name":"Physics in medicine and biology","volume":"70 9","pages":""},"PeriodicalIF":3.3,"publicationDate":"2025-05-02","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144049483","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"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 LET in intensity-modulated proton therapy with a miniaturized pixel detector.","authors":"Paulina Stasica-Dudek, Carlos Granja, Renata Kopeć, Dawid Krzempek, Cristina Oancea, Antoni Rucinski, Marzena Rydygier, Mateusz Winiarz, Jan Gajewski","doi":"10.1088/1361-6560/adcaf9","DOIUrl":"https://doi.org/10.1088/1361-6560/adcaf9","url":null,"abstract":"<p><p><i>Objective.</i>Given the increased interest in incorporating linear energy transfer (LET) as an optimization parameter in intensity-modulated proton therapy (IMPT), a solution for experimental validation of simulations and patient-specific quality assurance (PSQA) in terms of proton LET is needed. Here, we present the methodology and results of LET spectra measurements for spread-out Bragg peak (SOBP) and IMPT plans using a miniaturized pixel detector Timepix3.<i>Approach.</i>We used a MiniPIX Timepix3 detector that provides single-particle tracking, type-resolving power, and spectral information while allowing measurement in quasi-continuous mode. We performed measurements for SOBP and IMPT plans in homogeneous RW3 and heterogeneous CIRS head phantoms with reduced beam current. An artificial intelligence-based model was applied for proton identification and a GPU-accelerated FRED Monte Carlo (MC) code was applied for corresponding MC simulations.<i>Main results.</i>We compared the deposited energy and LET spectra obtained in mixed radiation fields from measurements and MC simulations. The peak positions of deposited energy and LET spectra for the SOBP and IMPT plans agree within the error bars. Discrepancies exceeding the error bars are only visible in the logarithmic scale in high-energy deposition and high-LET tails of the distributions. The mean relative difference of dose-averaged LET values between measurements and MC simulations for individual energy layers is about 5.1%.<i>Significance.</i>This study presents a methodology for assessing radiation quality in proton therapy through energy deposition and LET spectra measurements in uniform and clinical IMPT fields. Findings show an agreement between experimental data and MC simulations, validating our approach. The presented results demonstrate the feasibility of a commercially available Timepix3 detector to validate LET computations in IMPT fields and perform PSQA in terms of LET. This will support the implementation of LET in treatment planning, which will ultimately increase the effectiveness of the treatment.</p>","PeriodicalId":20185,"journal":{"name":"Physics in medicine and biology","volume":"70 9","pages":""},"PeriodicalIF":3.3,"publicationDate":"2025-04-29","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144021095","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"医学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"3D multiparametric ultrasound of spontaneous murine tumors for non-invasive tumor characterization.","authors":"Jean-Baptiste Guillaumin, Aymeric Nadjem, Léa Vigouroux, Ana Sibleyras, Mickaël Tanter, Jean-François Aubry, Béatrice Berthon","doi":"10.1088/1361-6560/adc8f4","DOIUrl":"10.1088/1361-6560/adc8f4","url":null,"abstract":"<p><p><i>Objective.</i>Non-invasive tumor diagnosis and characterization is limited today by the cost and availability of state of the art imaging techniques. Thanks to recent developments, ultrasound (US) imaging can now provide quantitative volumetric maps of different tissue characteristics. This study applied the first fully concurrent 3D ultrasound imaging set-up including B-mode imaging, shear wave elastography (SWE), tissue structure imaging with backscatter tensor imaging (BTI), vascular mapping with ultrasensitive Doppler (uDoppler) and ultrasound localization microscopy (ULM)<i>in-vivo</i>. Subsequent analysis aimed to evaluate its benefits for non-invasive tumor diagnosis.<i>Approach.</i>A total of 26 PyMT-MMTV transgenic mice and 6 control mice were imaged weekly during tumor growth. First-order statistics and radiomic features were extracted from the quantitative maps obtained, and used to build predictive models differentiating healthy from cancerous mammary pads. Imaging features were also compared to histology obtained the last week of imaging.<i>Main results.</i>High quality co-registered quantitative maps were obtained, for which SWE speed, BTI tissue organization, ULM blood vessel count and uDoppler blood vessel density were correlated with histopathology. Significant changes in uDoppler sensitivity and BTI tissue structure were measured during tumor evolution. Predictive models inferring the cancerous state from the multiparametric imaging reached 99% accuracy, and focused mainly on radiomics measures of the BTI maps.<i>Significance.</i>This work indicates the relevance of a multiparametric characterization of lesions, and highlights the strong predictive power of BTI-derived parameters for differentiating tumors from healthy tissue, both before and after the tumor can be detected by palpation.</p>","PeriodicalId":20185,"journal":{"name":"Physics in medicine and biology","volume":" ","pages":""},"PeriodicalIF":3.3,"publicationDate":"2025-04-28","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143780886","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"医学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Absorbed and effective dose estimates in HR-pQCT of the distal radius and tibia: virtual dosimetry with a GPU-accelerated Monte Carlo code.","authors":"Laura Antonia Cerbone, Giovanni Mettivier, Youfang Lai, Xun Jia, Steven K Boyd, Paolo Russo","doi":"10.1088/1361-6560/adc9f6","DOIUrl":"10.1088/1361-6560/adc9f6","url":null,"abstract":"<p><p><i>Objective</i>. To obtain maps of absorbed dose and an estimate of the effective dose to an adult patient for a high resolution peripheral quantitative computed tomography (HR-pQCT) (XtremeCT II) examination of the distal tibia and radius, using a graphical processing unit (GPU)-based Monte Carlo (MC) code.<i>Approach</i>. We adapted the validated code gCTD (GPU-based CT Dose calculator), to replicate the HR-pQCT configuration. MC simulations were performed on digital phantoms of the tibia and radius obtained from bilateral scans of the ankle and wrist of a 25 year-old female volunteer. Scans were segmented using an ad hoc algorithm in Fiji. Simulations run on an NVIDIA GeForce RTX 3090 GPU board. MC dose estimates were validated via computed tomography dose index measurements.<i>Main Results.</i>We obtained the absorbed dose distribution in the skin, bone, bone marrow, fat, and muscle tissues. The effective dose for the HR-pQCT examination were 2.05<i>μ</i>Sv and 2.13<i>μ</i>Sv for the right and left tibia, and 1.48<i>μ</i>Sv and 1.49<i>μ</i>Sv for the right and left radius, respectively, with a Type A statistical uncertainty of 0.06% (<i>k</i>= 3) with 4.66 × 10¹¹photon histories. Corresponding effective dose conversion coefficients (<i>k-factors</i>) were 0.185<i>μ</i>Sv ∙ mGy^-1· cm^-1(tibia), and 0.133<i>μ</i>Sv mGy^-1· cm^-1(radius).<i>Significance.</i>We reported the first independent estimate of the effective dose for standard HR-pQCT clinical scans of the distal tibia and radius with the XtremeCT II scanner. Effective dose estimates (considering a total relative uncertainty of less than 40%) were lower than those indicated by the manufacturer and commonly reported for these scans. With 4.66 × 10⁹photon histories, the gCTD MC code can produce 3D dose maps from segmented HR-pQCT images in less than 12 s (GPU time), with 0.9% (<i>k</i>= 3) statistical uncertainty, making real-time personalized dose estimate feasible.</p>","PeriodicalId":20185,"journal":{"name":"Physics in medicine and biology","volume":" ","pages":""},"PeriodicalIF":3.3,"publicationDate":"2025-04-28","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143803990","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"医学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}