Medical physics最新文献

{"title":"List of Advertisers","authors":"","doi":"10.1002/mp.17208","DOIUrl":"https://doi.org/10.1002/mp.17208","url":null,"abstract":"","PeriodicalId":18384,"journal":{"name":"Medical physics","volume":"52 5","pages":"3498"},"PeriodicalIF":3.2,"publicationDate":"2025-05-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://onlinelibrary.wiley.com/doi/epdf/10.1002/mp.17208","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143919467","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":"Cover","authors":"","doi":"10.1002/mp.17207","DOIUrl":"https://doi.org/10.1002/mp.17207","url":null,"abstract":"","PeriodicalId":18384,"journal":{"name":"Medical physics","volume":"52 5","pages":"C1"},"PeriodicalIF":3.2,"publicationDate":"2025-05-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://onlinelibrary.wiley.com/doi/epdf/10.1002/mp.17207","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143919823","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":"Cover","authors":"","doi":"10.1002/mp.17204","DOIUrl":"https://doi.org/10.1002/mp.17204","url":null,"abstract":"","PeriodicalId":18384,"journal":{"name":"Medical physics","volume":"52 4","pages":"C1"},"PeriodicalIF":3.2,"publicationDate":"2025-04-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://onlinelibrary.wiley.com/doi/epdf/10.1002/mp.17204","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143784282","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":"List of Advertisers","authors":"","doi":"10.1002/mp.17205","DOIUrl":"https://doi.org/10.1002/mp.17205","url":null,"abstract":"","PeriodicalId":18384,"journal":{"name":"Medical physics","volume":"52 4","pages":"2697"},"PeriodicalIF":3.2,"publicationDate":"2025-04-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://onlinelibrary.wiley.com/doi/epdf/10.1002/mp.17205","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143784305","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 novel skeletal muscle quantitative method and deep learning-based sarcopenia diagnosis for cervical cancer patients treated with radiotherapy","authors":"Zhe Wu,&nbsp;Lihua Deng,&nbsp;Wanyang Wu,&nbsp;Bin Zeng,&nbsp;Cheng Xu,&nbsp;Li Liu,&nbsp;Mujun Liu,&nbsp;Yi Wu","doi":"10.1002/mp.17791","DOIUrl":"10.1002/mp.17791","url":null,"abstract":"<div>\u0000 \u0000 \u0000 <section>\u0000 \u0000 <h3> Background</h3>\u0000 \u0000 <p>Sarcopenia is associated with decreased survival in cervical cancer patients treated with radiotherapy. Cone-beam computed tomography (CBCT) was widely used in image-guided radiotherapy. Sarcopenia is assessed by the skeletal muscle index (SMI) of third lumbar vertebra (L3). Whereas, L3 is usually not included on the cervical cancer radiotherapy CBCT images.</p>\u0000 </section>\u0000 \u0000 <section>\u0000 \u0000 <h3> Purpose</h3>\u0000 \u0000 <p>We aimed to explore the usefulness of CBCT for evaluating SMI and deep learning (DL)-based automatic segmentation and sarcopenia diagnosis for cervical cancer radiotherapy patients. We evaluated the SMI through fifth lumbar vertebra (L5).</p>\u0000 </section>\u0000 \u0000 <section>\u0000 \u0000 <h3> Methods</h3>\u0000 \u0000 <p>First, L3, L5 skeletal muscle area (SMA) were measured on CT and CBCT. The agreement of L5 skeletal muscle segmentation on CBCT was evaluated using the intraclass correlation coefficient (ICC). The relationships between L5-SMI_CT and L3-SMI_CT, L5-SMI_CBCT were established and assessed by Pearson analysis, Bland-Altman plots. Second, the consequent CBCT images of 248 cervical cancer radiotherapy patients with whole L5 were collected as DL-based automatic segmentation. An independent external validation dataset was used. We proposed an end-to-end anatomical distance-guided dual branch feature fusion network to segment L5 skeletal muscle on CBCT images. The automatic segmentation results were used for sarcopenia diagnosis evaluation.</p>\u0000 </section>\u0000 \u0000 <section>\u0000 \u0000 <h3> Results</h3>\u0000 \u0000 <p>The ICC values were greater than 0.95. The Pearson correlation coefficients (PCC) between L5-SMI_CT and L3-SMI_CT is 0.894. The PCC between L5-SMI_CT and L5-SMI_CBCT is 0.917. The L3-SMI_CT could be estimated through L5-SMI_CBCT by a linear regression equation. The adjusted <i>R</i>² values were greater than 0.7. The dice similarity coefficient of automatic segmentation is 87.09%. Our proposed DL network predicted sarcopenia with 84.38% accuracy and 85.71% F1-score. In external validation dataset, the sarcopenia diagnosis accuracy and F1-score are 80% and 82.61%, respectively.</p>\u0000 </section>\u0000 \u0000 <section>\u0000 \u0000 <h3> Conclusion</h3>\u0000 \u0000 <p>The SMI quantitative measurement using CBCT for cervical cancer patients is feasible. And the DL network has the potential to assist in the sarcopenia diagnosis using CBCT images.</p>\u0000 </section>\u0000 </div>","PeriodicalId":18384,"journal":{"name":"Medical physics","volume":"52 5","pages":"2887-2897"},"PeriodicalIF":3.2,"publicationDate":"2025-04-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143766251","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":"Robust Fourier-based slanted-edge method to measure scatter ratio","authors":"Lisa M. Garland,&nbsp;Ian A. Cunningham","doi":"10.1002/mp.17765","DOIUrl":"10.1002/mp.17765","url":null,"abstract":"<div>\u0000 \u0000 \u0000 <section>\u0000 \u0000 <h3> Background</h3>\u0000 \u0000 <p>Patient scatter incident on an x-ray detector reduces radiographic contrast and adds quantum noise, and minimizing scatter is critical in some specialized techniques such as dual-energy and energy-subtraction methods. Existing methods to measure scatter are either labor-intensive (multiple disks) or not appropriate to use in radiography where scatter often exceeds the width of the x-ray beam.</p>\u0000 </section>\u0000 \u0000 <section>\u0000 \u0000 <h3> Purpose</h3>\u0000 \u0000 <p>Develop a method to measure the scatter-to-primary ratio (SPR) that can be used for a wide range of radiographic and mammographic conditions, both with scatter equilibrium (scatter function does not exceed primary-beam width) and without.</p>\u0000 </section>\u0000 \u0000 <section>\u0000 \u0000 <h3> Methods</h3>\u0000 \u0000 <p>Fourier theory is used to show the SPR can be measured from the low-frequency drop (LFD) of the Fourier transform of the derivative of a normalized edge profile. The method was validated both experimentally and by simulation for radiography and mammography under scatter equilibrium and nonequilibrium conditions.</p>\u0000 </section>\u0000 \u0000 <section>\u0000 \u0000 <h3> Results</h3>\u0000 \u0000 <p>The theoretical derivation showed that by normalizing an edge profile with a profile without the edge, scatter equilibrium is not required and the method accommodates a nonuniform primary beam from beam divergence and Heel effect. The method was validated by a simulation study for a range of scatter-LSF widths, primary-beam widths, and image regions of interest used in the analysis. Experimental scatter measurements agreed with a similar edge-method published by Cooper when scatter equilibrium is achieved.</p>\u0000 </section>\u0000 \u0000 <section>\u0000 \u0000 <h3> Conclusions</h3>\u0000 \u0000 <p>A simple and direct method of measuring the SPR obtained with both uniform and nonuniform test phantoms is described. Validated both experimentally and theoretically, it uses the Fourier LFD obtained from a normalized slanted-edge profile and works for a wide range of practical mammographic and radiographic conditions.</p>\u0000 </section>\u0000 </div>","PeriodicalId":18384,"journal":{"name":"Medical physics","volume":"52 5","pages":"2810-2823"},"PeriodicalIF":3.2,"publicationDate":"2025-03-24","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://onlinelibrary.wiley.com/doi/epdf/10.1002/mp.17765","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143701415","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":"Benchmarking of a new integrated 3D dosimetry system against Monte Carlo calculations and an established optical CT scanner","authors":"Kawtar Lakrad,&nbsp;Mark Oldham,&nbsp;Benjamin Quinn,&nbsp;Justus Adamson","doi":"10.1002/mp.17773","DOIUrl":"10.1002/mp.17773","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;Advanced radiation therapy techniques, including intensity-modulated radiation therapy (IMRT), stereotactic radiosurgery (SRS), adaptive therapy, and proton therapy, offer high precision in delivering radiation doses to tumors while minimizing exposure to surrounding healthy tissues. These sophisticated methods necessitate stringent quality assurance (QA) measures to ensure their accuracy and safety. Three-dimensional (3D) dosimetry systems have the potential to play an important role in this context for verifying dose distributions in a comprehensive manner but have not been widely implemented partially due to a lack of streamlined systems that include dosimeter, readout, and analysis.&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 ClearView radiochromic dosimeter, the Vista 16 Optical CT scanner, and the VistaAce analysis software have the potential as a fully integrated 3D dosimetry tool for commissioning and verifying complex radiotherapy treatment plans. We aim to benchmark this integrated 3D dosimetry system and investigate its clinical utility.&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;The performance of this system was benchmarked against an independent Monte Carlo dose calculation software, the Duke Large Field of View Optical CT Scanner (DLOS), and an open-source analysis software (3D Slicer v4.13). We measured two simple radiotherapy plans and a selection from the AAPM (American Association of Physicists in Medicine) Task Group 119 IMRT commissioning tests. Treatment plans were prepared within the Eclipse planning system (AAA v15.6.03) after which a Varian Truebeam linac was used to deliver the treatment plans. Vista 16 was used to reconstruct the measured 3D dose distribution which was compared to the dose distribution obtained from an independent Monte Carlo-based dose calculation algorithm, as well as the 3D dose distribution reconstructed using the well-established DLOS. Image registration, conversion from optical density to dose, and comparative analysis were done using the VistaAce software and validated against results obtained using 3D Slicer for a subset of tests.&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;ClearView dosimeters exhibited a linear dose–response up to 60 Gy. For the 3-field benchmarking irradiation, the agreement (2%/2 mm 3D global gamma Index, 10% threshold) between ClearView/VistaAce versus the TPS and Monte Carlo was 97.8% and 98.8%, respectively. For the AAPM TG119 mock head and neck plan, the agreement (2%/2 mm) with the treatment planning system and Monte Carlo was 99.1% and 95.1%, respectively. For the TG119 mock prostate, the agreement was ","PeriodicalId":18384,"journal":{"name":"Medical physics","volume":"52 5","pages":"3377-3390"},"PeriodicalIF":3.2,"publicationDate":"2025-03-23","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143694972","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":"Remote sensing of high energy particle current generated by megavoltage x-rays","authors":"Arith Rajapakse,&nbsp;Coral Outwater,&nbsp;Davide Brivio,&nbsp;Erno Sajo,&nbsp;Piotr Zygmanski","doi":"10.1002/mp.17756","DOIUrl":"10.1002/mp.17756","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;In x-ray radiography and computed tomography (CT), absorbed dose is deposited in a radiation detector array in the form of charge carriers and collected. While these modalities are the standard for clinical imaging during the radiation therapy process, they require the use of bulk materials and adequate operating voltages. These constraints leave space for an imaging/dosimetry niche favoring low profile, low power, and non-invasive modalities.&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 conversion of therapeutic radiation to absorbed dose begins with the generation of high energy electrons. If utilized correctly, the high energy particle currents (HEC) offer a unique prospect for a novel form of imaging and dosimetry. In this paper, we establish the theoretical and experimental framework behind the sensing of HEC by measuring currents in various homogeneous and heterogeneous phantoms and comparing the measured signals to both one-dimensional particle transport and Monte Carlo (MC) based simulations.&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;The experimental setup for HEC sensing consists of pairs of complementary electrodes placed upstream and downstream of the object or phantom in question. When irradiated with 6MV x-rays, two signals, &lt;i&gt;s&lt;sub&gt;1&lt;/sub&gt;&lt;/i&gt;, and &lt;i&gt;s&lt;sub&gt;2&lt;/sub&gt;&lt;/i&gt;, were collected with zero external bias. These signals are coupled to each other due to the distribution of HEC inside the phantom. Both homogeneous (water) and heterogeneous (water and bone) phantoms were irradiated, and the measured signals were reviewed against simulations (MCNP6, CEPXS).&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 measured signals &lt;i&gt;s&lt;sub&gt;1&lt;/sub&gt;&lt;/i&gt; and &lt;i&gt;s&lt;sub&gt;2&lt;/sub&gt;&lt;/i&gt; (as a function of water equivalent thickness [WET]) for homogeneous phantoms matched the trends established by the corresponding radiation transport simulations; indicating that these signals convey information about the distribution of HEC inside the phantoms. Based on these findings, new signal metrics, &lt;i&gt;α&lt;/i&gt; and &lt;i&gt;β&lt;/i&gt;, were formalized and used to quantify the scanning of heterogeneous phantoms.&lt;/p&gt;\u0000 &lt;/section&gt;\u0000 \u0000 &lt;section&gt;\u0000 \u0000 &lt;h3&gt; Conclusion&lt;/h3&gt;\u0000 \u0000 &lt;p&gt;In this work, we demonstrated that information about the internal composition of an object can be obtained through HEC sensing. Specifically, the distribution of HEC inside of an object resulting from x-ray irradiation was measured using a simple system of planar electrodes and agreed well with radiation transport simulations. HEC sensing has the potential to be a disruptive met","PeriodicalId":18384,"journal":{"name":"Medical physics","volume":"52 5","pages":"3258-3269"},"PeriodicalIF":3.2,"publicationDate":"2025-03-19","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143660160","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":"Study of linear energy transfer effect on rib fracture in breast cancer patients receiving pencil-beam-scanning proton therapy","authors":"Yunze Yang,&nbsp;Kimberly R. Gergelis,&nbsp;Jiajian Shen,&nbsp;Arslan Afzal,&nbsp;Trey C. Mullikin,&nbsp;Robert W. Gao,&nbsp;Khaled Aziz,&nbsp;Dean A. Shumway,&nbsp;Kimberly S. Corbin,&nbsp;Wei Liu,&nbsp;Robert W. Mutter","doi":"10.1002/mp.17745","DOIUrl":"10.1002/mp.17745","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;In breast cancer patients treated with pencil-beam scanning proton therapy (PBS), the increased linear energy transfer (LET) near the end of the proton range can affect nearby ribs. This may associate with a higher risk of rib fractures.&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;To study the effect of LET on rib fracture in breast cancer patients treated with PBS using a novel tool of dose-LET volume histogram (DLVH).&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;From a prospective registry of patients treated with post-mastectomy proton therapy to the chest wall and regional lymph nodes for breast cancer between 2015 and 2020, we retrospectively identified rib fracture cases detected after completing treatment. Contemporaneously treated control patients who did not develop rib fracture were matched to patients 2:1 considering prescription dose, boost location, reconstruction status, laterality, chest wall thickness, and treatment year. The DLVH index, &lt;i&gt;V&lt;/i&gt;(d, l), defined as volume(&lt;i&gt;V&lt;/i&gt;) of the structure with at least dose(d) and dose-averaged LET (l) (LETd), was calculated. DLVH plots between the fracture and control group were compared. Conditional logistic regression (CLR) model was used to establish the relation of &lt;i&gt;V&lt;/i&gt;(d, l) and the observed fracture at each combination of &lt;i&gt;d&lt;/i&gt; and &lt;i&gt;l&lt;/i&gt;. The &lt;i&gt;p&lt;/i&gt;-value derived from CLR model shows the statistical difference between fracture patients and the matched control group. Using the 2D &lt;i&gt;p&lt;/i&gt;-value map derived from CLR model, the DLVH features associated with the patient outcomes were extracted.&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;Seven rib fracture patients were identified, and fourteen matched patients were selected for the control group. The median time from the completion of proton therapy to rib fracture diagnosis was 12 months (range 5–14 months). Two patients had grade 2 symptomatic rib fracture while the remaining 5 were grade 1 incidentally detected on imaging. The derived &lt;i&gt;p&lt;/i&gt;-value map demonstrated larger &lt;i&gt;V&lt;/i&gt;(0–36 Gy[RBE], 4.0–5.0 keV/µm) in patients experiencing fracture (&lt;i&gt;p &lt;/i&gt;&lt; 0.1). For example, the &lt;i&gt;p&lt;/i&gt;-value for &lt;i&gt;V&lt;/i&gt;(30 Gy[RBE], 4.0 keV/um) was 0.069.&lt;/p&gt;\u0000 &lt;/section&gt;\u0000 \u0000 &lt;section&gt;\u0000 \u0000 &lt;h3&gt; Conclusion&lt;/h3&gt;\u0000 \u0000 &lt;p&gt;In breast cancer patients receiving PBS, a larger volume of chest wall receiving moderate dose and high LETd may result in an increased risk of rib fracture.&lt;/p&gt;\u0000 &lt;/section&gt;\u0000 ","PeriodicalId":18384,"journal":{"name":"Medical physics","volume":"52 5","pages":"3428-3438"},"PeriodicalIF":3.2,"publicationDate":"2025-03-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://onlinelibrary.wiley.com/doi/epdf/10.1002/mp.17745","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143660164","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":"Impact of nuclear fragmentation and irradiation scenarios on the dose-averaged LET, the RBE, and their relationship for H, He, C, O, and Ne ions","authors":"Alessio Parisi,&nbsp;Keith M. Furutani,&nbsp;Chris J. Beltran","doi":"10.1002/mp.17755","DOIUrl":"10.1002/mp.17755","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;Projectile and target fragmentation are nuclear phenomena that can influence the computation of the linear energy transfer (LET) and the relative biological effectiveness (RBE) in external radiotherapy with accelerated ions. Correlations between these two quantities are routinely established during radiobiological experiments to interpret the results and to develop and calibrate RBE models.&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 systematically evaluates the impact of secondary fragments and irradiation scenarios on the dose-averaged LET, the RBE, and their correlation in the case of exposures to clinically relevant ion beams.&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;57 600 microdosimetric lineal energy spectra and corresponding LET distributions were simulated with the Monte Carlo code PHITS across different scenarios, including track segment calculations, pristine, and spread-out Bragg peaks of &lt;sup&gt;1&lt;/sup&gt;H, &lt;sup&gt;4&lt;/sup&gt;He, &lt;sup&gt;12&lt;/sup&gt;C, &lt;sup&gt;16&lt;/sup&gt;O, and &lt;sup&gt;20&lt;/sup&gt;Ne ions within water phantoms. The LET distributions were analyzed to calculate the dose-average LET, both including or excluding the contribution of secondary ions of an element different from the primary beam. Similarly, the lineal energy distributions were processed in conjunction with the Mayo Clinic Florida microdosimetric kinetic model to compute the RBE for two theoretical cell lines (&lt;i&gt;α&lt;/i&gt;/&lt;i&gt;β&lt;/i&gt; = 2 and 10 Gy in the case of 6 MV x-rays). Correlations between the RBE and dose-averaged LET were established by analyzing the simulation results within water phantoms and then compared to the corresponding trends from the track segment calculations.&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;Excluding secondary fragments had a pronounced impact on the dose-averaged LET and the RBE, particularly in the entrance regions of proton beams and close to the distal edge of heavier ions. The correlations between the RBE and the dose-averaged LET were not universal, but highly dependent on the irradiation scenario. For proton beams only, the dose-averaged LET of hydrogen ions served as a practical first-order descriptor of the RBE. Track segment simulations, commonly used for calibrating and benchmarking RBE models, provided a reasonable approximation for low-energy beams but failed to fully capture the complexity of polyenergetic radiation fields.&lt;/p&gt;\u0000 &lt;/section&gt;\u0000 \u0000 &lt;section&gt;\u0000 \u0000 &lt;h3&gt; Conclusions&lt;/h3&gt;\u0000 \u0000 &lt;p&gt;Secondary fragments can substantially affect the dose-averaged LET and the RBE, even in proton beams. The dose-averaged LET,","PeriodicalId":18384,"journal":{"name":"Medical physics","volume":"52 5","pages":"3450-3460"},"PeriodicalIF":3.2,"publicationDate":"2025-03-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143660146","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}