Pub Date : 2026-02-01DOI: 10.1016/j.zemedi.2024.09.003
Quazi Muhammad Rashed Nizam , Asif Ahmed , Iftekhar Ahmed , Lembit Sihver
When high energetic heavy ions interact with any target, short range, high linear energy transfer (LET) target fragments are produced. These target fragments (TFs) can give a significant dose to the healthy tissue during heavy ion cancer therapy, and when cosmic radiation interacts with astronauts. This paper presents Monte Carlo simulations, using the Particle and Heavy Ion Transport code System (PHITS), to characterize target fragments from reactions of helium and carbon ions with water. The calculated ranges, LET, doses, and production cross sections are presented. It is shown that protons, deuterons, tritons, alpha particles, 3He, 6He, nitrogen, oxygen, and fluorine ions are the most probable target fragments when carbon and helium ions collide with water. Among the produced target fragments, alpha particles and nitrogen ions give the highest dose to the targets, since the combination of fluence and LETs of these TFs are highest among the produced fragments. The production cross sections of proton and oxygen are the highest among the target fragments cross sections when helium and carbon ions imping on water, because these TFs can be produced through more reaction channels compared to other fragments. These findings are helpful for accurate dose measurement during heavy ion cancer therapy and for shielding of space radiation.
{"title":"Monte Carlo calculations of target fragments from helium and carbon ion interactions with water","authors":"Quazi Muhammad Rashed Nizam , Asif Ahmed , Iftekhar Ahmed , Lembit Sihver","doi":"10.1016/j.zemedi.2024.09.003","DOIUrl":"10.1016/j.zemedi.2024.09.003","url":null,"abstract":"<div><div>When high energetic heavy ions interact with any target, short range, high linear energy transfer (LET) target fragments are produced. These target fragments (TFs) can give a significant dose to the healthy tissue during heavy ion cancer therapy, and when cosmic radiation interacts with astronauts. This paper presents Monte Carlo simulations, using the Particle and Heavy Ion Transport code System (PHITS), to characterize target fragments from reactions of helium and carbon ions with water. The calculated ranges, LET, doses, and production cross sections are presented. It is shown that protons, deuterons, tritons, alpha particles, <sup>3</sup>He, <sup>6</sup>He, nitrogen, oxygen, and fluorine ions are the most probable target fragments when carbon and helium ions collide with water. Among the produced target fragments, alpha particles and nitrogen ions give the highest dose to the targets, since the combination of fluence and LETs of these TFs are highest among the produced fragments. The production cross sections of proton and oxygen are the highest among the target fragments cross sections when helium and carbon ions imping on water, because these TFs can be produced through more reaction channels compared to other fragments. These findings are helpful for accurate dose measurement during heavy ion cancer therapy and for shielding of space radiation.</div></div>","PeriodicalId":54397,"journal":{"name":"Zeitschrift fur Medizinische Physik","volume":"36 1","pages":"Pages 26-35"},"PeriodicalIF":4.2,"publicationDate":"2026-02-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142407375","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"医学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2026-02-01DOI: 10.1016/j.zemedi.2025.03.003
Alberto Villagran Asiares , Teresa Vitadello , Osvaldo M. Velarde , Sylvia Schachoff , Tareq Ibrahim , Stephan G. Nekolla
Purpose
To comprehensively evaluate the effectiveness of FDG-PET/MRI multiparametric analysis in predicting myocardial wall motion recovery following revascularization of chronic coronary total occlusions (CTO), incorporating both traditional and machine learning approaches.
Methods
This retrospective study assessed fluorine-18 fluorodeoxyglucose uptake (FDG), late gadolinium enhanced MR imaging (LGE), and MR wall motion abnormalities (WMA) of the left ventricle walls of a clinical cohort with 21 CTO patients (62 ± 9 years, 20 men). All patients were examined using a PET/MRI prior to revascularization and a follow-up cardiac MRI six months later. Prediction models for wall motion recovery after perfusion restoration were developed using linear and nonlinear algorithms as well as multiparametric variables. Performance and prediction explainability were evaluated in a 5x2 cross-validation framework, using ROC AUC and McNemar’s test modified for clustered matched-pair data, and Shapley values.
Results
Based on 79 CTO-subtended myocardial wall segments with wall motion abnormalities at baseline, the reference logistic regression model LGE + FDG obtained 0.55(SE = 0.07) in the clustered ROC AUC (cROC AUC) and 0.17(0.05) in the Global Absolute Shapley value. The reference outperformed FDG standalone in cROC AUC (-35(17) %, p < 0.0001), but not LGE standalone (11(12) %, p > 0.05). There were no statistically significant differences between the marginal probabilities of success of these three models. Moreover, no significant improvements (differences < 10 % in cROC AUC, and < 20 % in Global Absolute Shapley, p > 0.05) were found when using mixed effects logistic regression, decision tree, k-nearest neighbor, Naive Bayes, random forest, and support vector machine, with multiparametric combinations of FDG, LGE, and/or WMA.
Conclusion
In this clinical cohort, adding more complex interactions between PET/MRI imaging of cardiac function, infarct extension, and/or metabolism did not enhance the prediction of wall motion recovery after perfusion restoration. This finding raises the question whether multiparametric FDG-PET/MRI analysis has demonstrable benefits in risk stratification for CTO revascularization. Further studies with larger cohorts and external validation datasets are crucial to clarify this question and refine the role of multiparametric imaging in this context.
{"title":"Can multiparametric FDG-PET/MRI analysis really enhance the prediction of myocardial recovery after CTO revascularization? A machine learning study","authors":"Alberto Villagran Asiares , Teresa Vitadello , Osvaldo M. Velarde , Sylvia Schachoff , Tareq Ibrahim , Stephan G. Nekolla","doi":"10.1016/j.zemedi.2025.03.003","DOIUrl":"10.1016/j.zemedi.2025.03.003","url":null,"abstract":"<div><h3>Purpose</h3><div>To comprehensively evaluate the effectiveness of FDG-PET/MRI multiparametric analysis in predicting myocardial wall motion recovery following revascularization of chronic coronary total occlusions (CTO), incorporating both traditional and machine learning approaches.</div></div><div><h3>Methods</h3><div>This retrospective study assessed fluorine-18 fluorodeoxyglucose uptake (FDG), late gadolinium enhanced MR imaging (LGE), and MR wall motion abnormalities (WMA) of the left ventricle walls of a clinical cohort with 21 CTO patients (62 ± 9 years, 20 men). All patients were examined using a PET/MRI prior to revascularization and a follow-up cardiac MRI six months later. Prediction models for wall motion recovery after perfusion restoration were developed using linear and nonlinear algorithms as well as multiparametric variables. Performance and prediction explainability were evaluated in a 5x2 cross-validation framework, using ROC AUC and McNemar’s test modified for clustered matched-pair data, and Shapley values.</div></div><div><h3>Results</h3><div>Based on 79 CTO-subtended myocardial wall segments with wall motion abnormalities at baseline, the reference logistic regression model LGE + FDG obtained 0.55(SE = 0.07) in the clustered ROC AUC (cROC AUC) and 0.17(0.05) in the Global Absolute Shapley value. The reference outperformed FDG standalone in cROC AUC (-35(17) %, p < 0.0001), but not LGE standalone (11(12) %, p > 0.05). There were no statistically significant differences between the marginal probabilities of success of these three models. Moreover, no significant improvements (differences < 10 % in cROC AUC, and < 20 % in Global Absolute Shapley, p > 0.05) were found when using mixed effects logistic regression, decision tree, k-nearest neighbor, Naive Bayes, random forest, and support vector machine, with multiparametric combinations of FDG, LGE, and/or WMA.</div></div><div><h3>Conclusion</h3><div>In this clinical cohort, adding more complex interactions between PET/MRI imaging of cardiac function, infarct extension, and/or metabolism did not enhance the prediction of wall motion recovery after perfusion restoration. This finding raises the question whether multiparametric FDG-PET/MRI analysis has demonstrable benefits in risk stratification for CTO revascularization. Further studies with larger cohorts and external validation datasets are crucial to clarify this question and refine the role of multiparametric imaging in this context.</div></div>","PeriodicalId":54397,"journal":{"name":"Zeitschrift fur Medizinische Physik","volume":"36 1","pages":"Pages 84-98"},"PeriodicalIF":4.2,"publicationDate":"2026-02-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144047745","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"医学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2026-02-01DOI: 10.1016/j.zemedi.2025.02.005
Tobias Haueise , Fritz Schick , Norbert Stefan , Elena Grune , Marc-Nicolas von Itter , Hans-Ulrich Kauczor , Johanna Nattenmüller , Tobias Norajitra , Tobias Nonnenmacher , Susanne Rospleszcz , Klaus H. Maier-Hein , Christopher L. Schlett , Jakob B. Weiss , Beate Fischer , Karl-Heinz Jöckel , Lilian Krist , Thoralf Niendorf , Annette Peters , Anja M. Sedlmeier , Stefan N. Willich , Jürgen Machann
Objectives
High prevalence of visceral obesity and its associated complications underscore the importance of accurately quantifying visceral adipose tissue (VAT) depots. While whole-body MRI offers comprehensive insights into adipose tissue distribution, it is resource-intensive. Alternatively, evaluation of defined single slices provides an efficient approach for estimation of total VAT volume. This study investigates the influence of sex-, age-, and BMI on VAT distribution along the craniocaudal axis and total VAT volume obtained from single slice versus volumetric assessment in 3D MRI and aims to identify age-independent locations for accurate estimation of VAT volume from single slice assessment.
Materials and methods
This secondary analysis of the prospective population-based German National Cohort (NAKO) included 3D VIBE Dixon MRI from 11,191 participants (screened between May 2014 and December 2016). VAT and spine segmentations were automatically generated using fat-selective images. Standardized craniocaudal VAT profiles were generated. Axial percentage of total VAT was used for identification of reference locations for volume estimation of VAT from a single slice.
Results
Data from 11,036 participants (mean age, 52 ± 11 years, 5681 men) were analyzed. Craniocaudal VAT distribution differed qualitatively between men/women and with respect to age/BMI. Age-independent single slice VAT estimates demonstrated strong correlations with reference VAT volumes. Anatomical locations for accurate VAT estimation varied with sex/BMI.
Conclusions
The selection of reference locations should be different depending on BMI groups, with a preference for caudal shifts in location with increasing BMI. For women with obesity (BMI >30 kg/m2), the L1 level emerges as the optimal reference location.
{"title":"Refining visceral adipose tissue quantification: Influence of sex, age, and BMI on single slice estimation in 3D MRI of the German National Cohort","authors":"Tobias Haueise , Fritz Schick , Norbert Stefan , Elena Grune , Marc-Nicolas von Itter , Hans-Ulrich Kauczor , Johanna Nattenmüller , Tobias Norajitra , Tobias Nonnenmacher , Susanne Rospleszcz , Klaus H. Maier-Hein , Christopher L. Schlett , Jakob B. Weiss , Beate Fischer , Karl-Heinz Jöckel , Lilian Krist , Thoralf Niendorf , Annette Peters , Anja M. Sedlmeier , Stefan N. Willich , Jürgen Machann","doi":"10.1016/j.zemedi.2025.02.005","DOIUrl":"10.1016/j.zemedi.2025.02.005","url":null,"abstract":"<div><h3>Objectives</h3><div>High prevalence of visceral obesity and its associated complications underscore the importance of accurately quantifying visceral adipose tissue (VAT) depots. While whole-body MRI offers comprehensive insights into adipose tissue distribution, it is resource-intensive. Alternatively, evaluation of defined single slices provides an efficient approach for estimation of total VAT volume. This study investigates the influence of sex-, age-, and BMI on VAT distribution along the craniocaudal axis and total VAT volume obtained from single slice versus volumetric assessment in 3D MRI and aims to identify age-independent locations for accurate estimation of VAT volume from single slice assessment.</div></div><div><h3>Materials and methods</h3><div>This secondary analysis of the prospective population-based German National Cohort (NAKO) included 3D VIBE Dixon MRI from 11,191 participants (screened between May 2014 and December 2016). VAT and spine segmentations were automatically generated using fat-selective images. Standardized craniocaudal VAT profiles were generated. Axial percentage of total VAT was used for identification of reference locations for volume estimation of VAT from a single slice.</div></div><div><h3>Results</h3><div>Data from 11,036 participants (mean age, 52 ± 11 years, 5681 men) were analyzed. Craniocaudal VAT distribution differed qualitatively between men/women and with respect to age/BMI. Age-independent single slice VAT estimates demonstrated strong correlations with reference VAT volumes. Anatomical locations for accurate VAT estimation varied with sex/BMI.</div></div><div><h3>Conclusions</h3><div>The selection of reference locations should be different depending on BMI groups, with a preference for caudal shifts in location with increasing BMI. For women with obesity (BMI >30 kg/m<sup>2</sup>), the L1 level emerges as the optimal reference location.</div></div>","PeriodicalId":54397,"journal":{"name":"Zeitschrift fur Medizinische Physik","volume":"36 1","pages":"Pages 114-124"},"PeriodicalIF":4.2,"publicationDate":"2026-02-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143695009","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"医学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2026-02-01DOI: 10.1016/j.zemedi.2024.09.002
Lena Heuchel , Stephan Garbe , Armin Lühr , Maya Shariff
In 2023, a Germany-wide survey on the current clinical practice of three different large field irradiation techniques (LFIT), namely total body irradiation (TBI), total skin irradiation (TSI) and craniospinal irradiation (CSI), was conducted covering different aspects of the irradiation process, e.g., the irradiation unit and technique, dosimetrical aspects and treatment planning as well as quality assurance. The responses provided a deep insight into the applied approaches showing a high heterogeneity between participating centers for all three large field irradiation techniques. The highest heterogeneity was found for TBI. Here, differences between centers were found in almost every aspect of the irradiation process, e.g., the irradiation technique, the prescription dose, the spared organs at risk and the applied treatment planning method. For TBI, the only agreement was found in the fractionation scheme (2 Gy/fraction, 2 fractions/day) and the dose reduction to the lung. TSI was the rarest of the three LFITs. For TSI, the only agreement was found in the use of 6 MeV when irradiating with electrons. The reported approaches of CSI were closest to standard radiotherapy, using no CSI-specific irradiation techniques or treatment planning methods. For CSI, the only agreement was found in the prescribed dose to the brain (50 – 60 Gy). When asking for future requirements, participating centers considered the lack of standardization as the most important future challenge and suggested to perform (retrospective) patient studies. The results of such studies can then serve as a basis for new and improved guidelines.
{"title":"Large-field irradiation techniques in Germany: A DGMP Working Group survey on the current clinical implementation of total body irradiation, total skin irradiation and craniospinal irradiation","authors":"Lena Heuchel , Stephan Garbe , Armin Lühr , Maya Shariff","doi":"10.1016/j.zemedi.2024.09.002","DOIUrl":"10.1016/j.zemedi.2024.09.002","url":null,"abstract":"<div><div>In 2023, a Germany-wide survey on the current clinical practice of three different large field irradiation techniques (LFIT), namely total body irradiation (TBI), total skin irradiation (TSI) and craniospinal irradiation (CSI), was conducted covering different aspects of the irradiation process, e.g., the irradiation unit and technique, dosimetrical aspects and treatment planning as well as quality assurance. The responses provided a deep insight into the applied approaches showing a high heterogeneity between participating centers for all three large field irradiation techniques. The highest heterogeneity was found for TBI. Here, differences between centers were found in almost every aspect of the irradiation process, e.g., the irradiation technique, the prescription dose, the spared organs at risk and the applied treatment planning method. For TBI, the only agreement was found in the fractionation scheme (2 Gy/fraction, 2 fractions/day) and the dose reduction to the lung. TSI was the rarest of the three LFITs. For TSI, the only agreement was found in the use of 6 MeV when irradiating with electrons. The reported approaches of CSI were closest to standard radiotherapy, using no CSI-specific irradiation techniques or treatment planning methods. For CSI, the only agreement was found in the prescribed dose to the brain (50 – 60 Gy). When asking for future requirements, participating centers considered the lack of standardization as the most important future challenge and suggested to perform (retrospective) patient studies. The results of such studies can then serve as a basis for new and improved guidelines.</div></div>","PeriodicalId":54397,"journal":{"name":"Zeitschrift fur Medizinische Physik","volume":"36 1","pages":"Pages 16-25"},"PeriodicalIF":4.2,"publicationDate":"2026-02-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142485130","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"医学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2026-02-01DOI: 10.1016/j.zemedi.2025.02.001
Tobias Rader , Lisa Lippl , Joachim Müller
Objective
In recent years, there has been a trend toward more individualization in the fitting of cochlear implants (CI). Here, a new individualized approach to frequency band allocation was used. This approach is based on binaural perceptual pitch matching.
Patient
The patient had congenital bilateral progressive sensorineural hearing loss due to Usher Syndrome. He had used hearing aids in both ears since the age of 4 years. In his mid-40s, he received a CI on his right ear and, ten months later, a second CI on the left ear.
Intervention
Adjustments to the frequency band allocations were made, guided by the binaural perceptual pitch matching of piano notes. For the first CI, pitch matching was performed using the contralateral ear as the reference, which had preserved low-frequency residual hearing (bimodal pitch matching). For the second CI, pitch matching was performed using the first implanted side as the reference (bilateral electrical pitch matching).
Results
The final frequency band allocation adjustments were always shifted toward lower frequencies relative to the default band allocations. The adjustments were larger in magnitude for the second CI compared to the first CI. Speech perception scores generally increased over the course of rehabilitation and were higher with the individualized fitting compared to the default fitting. The subjective sound quality was reportedly greatly improved with the individualized fitting.
Conclusions
Individualized psychoacoustic frequency-based fitting can yield improvements in the perceived sound quality with a CI. However, this method requires significant residual hearing in at least one ear, and the patient must have relatively fine pitch discrimination abilities.
{"title":"Improvement of perceived cochlear implant sound quality through individualized psychoacoustic-based frequency fitting","authors":"Tobias Rader , Lisa Lippl , Joachim Müller","doi":"10.1016/j.zemedi.2025.02.001","DOIUrl":"10.1016/j.zemedi.2025.02.001","url":null,"abstract":"<div><h3>Objective</h3><div>In recent years, there has been a trend toward more individualization in the fitting of cochlear implants (CI). Here, a new individualized approach to frequency band allocation was used. This approach is based on binaural perceptual pitch matching.</div></div><div><h3>Patient</h3><div>The patient had congenital bilateral progressive sensorineural hearing loss due to Usher Syndrome. He had used hearing aids in both ears since the age of 4 years. In his mid-40s, he received a CI on his right ear and, ten months later, a second CI on the left ear.</div></div><div><h3>Intervention</h3><div>Adjustments to the frequency band allocations were made, guided by the binaural perceptual pitch matching of piano notes. For the first CI, pitch matching was performed using the contralateral ear as the reference, which had preserved low-frequency residual hearing (bimodal pitch matching). For the second CI, pitch matching was performed using the first implanted side as the reference (bilateral electrical pitch matching).</div></div><div><h3>Results</h3><div>The final frequency band allocation adjustments were always shifted toward lower frequencies relative to the default band allocations. The adjustments were larger in magnitude for the second CI compared to the first CI. Speech perception scores generally increased over the course of rehabilitation and were higher with the individualized fitting compared to the default fitting. The subjective sound quality was reportedly greatly improved with the individualized fitting.</div></div><div><h3>Conclusions</h3><div>Individualized psychoacoustic frequency-based fitting can yield improvements in the perceived sound quality with a CI. However, this method requires significant residual hearing in at least one ear, and the patient must have relatively fine pitch discrimination abilities.</div></div>","PeriodicalId":54397,"journal":{"name":"Zeitschrift fur Medizinische Physik","volume":"36 1","pages":"Pages 125-130"},"PeriodicalIF":4.2,"publicationDate":"2026-02-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143532032","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"医学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2026-02-01DOI: 10.1016/j.zemedi.2025.03.002
Hannes A. Loebner, Jenny Bertholet, Paul-Henry Mackeprang, Werner Volken, Michael K. Fix, Peter Manser
<div><h3>Purpose</h3><div>Robustness assessment is an essential part of radiotherapy plan quality assessment. However, it is often not evaluated in photon-based radiotherapy. This study aims to conduct a robustness audit to establish a baseline for the role of plan robustness in Switzerland by assessing and comparing robustness across plans from and clinical workflows in multiple institutions.</div></div><div><h3>Materials and methods</h3><div>A multi-institutional study involving 11 Swiss institutions was conducted. Each institution provided treatment plans for three cases and completed a questionnaire on treatment planning and assessment of robustness in their clinical practice.</div><div>The plans were planned using the Eclipse treatment planning system and utilized intensity-modulated techniques using a 6 MV flattened photon beam for one brain case, and one unilateral and one bilateral head and neck cases, prescribed 60.0 Gy (one phase), 70.0 Gy (two phases) and 70.0 Gy (three phases) to 95% of the target volume, respectively. Institutions used their standard institutional protocols for the provided CT, structures and prescription. Dose distributions were subsequently recalculated in an in-house Monte Carlo (MC) framework incorporating clinically motivated uncertainties associated to patient setup and multi-leaf collimator (MLC) positions. The uncertainties’ impact on the dosimetric plan quality was assessed by evaluating representative target and organ-at-risk (OAR) dose-volume endpoints (e.g. D98% and D2% of the target, mean dose of parallel OARs and near max dose of serial OARs).</div></div><div><h3>Results</h3><div>Differences in target and OAR dose-volume endpoints in the presence of random patient setup uncertainties (Gaussian distributed with σ = 0.2 cm in the three translational and σ = 0.5° in the three rotational axes) were smaller than ±0.5 Gy. Exceptions were the near max dose-volume endpoints of structures near the target with differences up to ±2.2 Gy for the optic nerve in the brain case. Systematic rotational patient setup uncertainties of ≤3° in either pitch, yaw or roll had similar impact as translational uncertainties ≤0.3 cm in either left-right, superior inferior or anterior-posterior direction with maximal differences in most investigated dose-volume endpoints of 9.0 Gy. Systematic MLC uncertainties of +0.5 mm of all leaves led to an average increase of up to 3.0 Gy in the dose-volume endpoints.</div><div>The questionnaire revealed diverse practices in terms of planning and assessment for robustness: all institutions use target and OAR margins, 2/11 use robust optimization and 5/11 regularly perform robustness assessments of treatment plans by recalculating the dose distribution including uncertainties. The importance of robustness in treatment planning was rated ≥8 out of 10 (10 as most important) by 6/11 institutions. The need for better commercial tools to assess or integrate robustness into treatment planning was exp
{"title":"Robustness assessment of radiotherapy treatment plans in Switzerland","authors":"Hannes A. Loebner, Jenny Bertholet, Paul-Henry Mackeprang, Werner Volken, Michael K. Fix, Peter Manser","doi":"10.1016/j.zemedi.2025.03.002","DOIUrl":"10.1016/j.zemedi.2025.03.002","url":null,"abstract":"<div><h3>Purpose</h3><div>Robustness assessment is an essential part of radiotherapy plan quality assessment. However, it is often not evaluated in photon-based radiotherapy. This study aims to conduct a robustness audit to establish a baseline for the role of plan robustness in Switzerland by assessing and comparing robustness across plans from and clinical workflows in multiple institutions.</div></div><div><h3>Materials and methods</h3><div>A multi-institutional study involving 11 Swiss institutions was conducted. Each institution provided treatment plans for three cases and completed a questionnaire on treatment planning and assessment of robustness in their clinical practice.</div><div>The plans were planned using the Eclipse treatment planning system and utilized intensity-modulated techniques using a 6 MV flattened photon beam for one brain case, and one unilateral and one bilateral head and neck cases, prescribed 60.0 Gy (one phase), 70.0 Gy (two phases) and 70.0 Gy (three phases) to 95% of the target volume, respectively. Institutions used their standard institutional protocols for the provided CT, structures and prescription. Dose distributions were subsequently recalculated in an in-house Monte Carlo (MC) framework incorporating clinically motivated uncertainties associated to patient setup and multi-leaf collimator (MLC) positions. The uncertainties’ impact on the dosimetric plan quality was assessed by evaluating representative target and organ-at-risk (OAR) dose-volume endpoints (e.g. D98% and D2% of the target, mean dose of parallel OARs and near max dose of serial OARs).</div></div><div><h3>Results</h3><div>Differences in target and OAR dose-volume endpoints in the presence of random patient setup uncertainties (Gaussian distributed with σ = 0.2 cm in the three translational and σ = 0.5° in the three rotational axes) were smaller than ±0.5 Gy. Exceptions were the near max dose-volume endpoints of structures near the target with differences up to ±2.2 Gy for the optic nerve in the brain case. Systematic rotational patient setup uncertainties of ≤3° in either pitch, yaw or roll had similar impact as translational uncertainties ≤0.3 cm in either left-right, superior inferior or anterior-posterior direction with maximal differences in most investigated dose-volume endpoints of 9.0 Gy. Systematic MLC uncertainties of +0.5 mm of all leaves led to an average increase of up to 3.0 Gy in the dose-volume endpoints.</div><div>The questionnaire revealed diverse practices in terms of planning and assessment for robustness: all institutions use target and OAR margins, 2/11 use robust optimization and 5/11 regularly perform robustness assessments of treatment plans by recalculating the dose distribution including uncertainties. The importance of robustness in treatment planning was rated ≥8 out of 10 (10 as most important) by 6/11 institutions. The need for better commercial tools to assess or integrate robustness into treatment planning was exp","PeriodicalId":54397,"journal":{"name":"Zeitschrift fur Medizinische Physik","volume":"36 1","pages":"Pages 47-59"},"PeriodicalIF":4.2,"publicationDate":"2026-02-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144016576","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"医学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2026-02-01DOI: 10.1016/j.zemedi.2024.12.003
Eric D. Ehler, Parham Alaei
The purpose of this work was to evaluate the imaging dose for the Accuray Radixact ClearRT system. Low-contrast resolution and CT number consistency was evaluated as well. CTDI measurements were compared to vendor supplied values, and similar measurements were done on a Varian TrueBeam kV cone-beam CT (CBCT) and a Philips Big Bore CT scanner. In-field imaging doses were measured using various protocols in an anthropomorphic phantom, while out-of-field doses were measured 10 cm from the imaging field edge. Comparison of the CTDI and the in-field doses showed considerable disagreement when the patient anatomy size was not congruent with the size of the CTDI phantom. While that is an expected outcome, this work provides an estimate of the differences for a variety of ClearRT protocols when this situation arises. The CNR was measured for all combinations of ClearRT settings for comparisons within the system, as well as for a comparison with a CBCT and fan-beam CT system. The CNR and dose information provided in this work can be used to aid in selecting a ClearRT imaging protocol. The CT number stability was tracked over 27 months; two instances where the CT number constancy exceeded tolerance were observed after service.
{"title":"Imaging dose and image quality of kilovoltage imaging implemented on a helical tomotherapy unit","authors":"Eric D. Ehler, Parham Alaei","doi":"10.1016/j.zemedi.2024.12.003","DOIUrl":"10.1016/j.zemedi.2024.12.003","url":null,"abstract":"<div><div>The purpose of this work was to evaluate the imaging dose for the Accuray Radixact ClearRT system. Low-contrast resolution and CT number consistency was evaluated as well. CTDI measurements were compared to vendor supplied values, and similar measurements were done on a Varian TrueBeam kV cone-beam CT (CBCT) and a Philips Big Bore CT scanner. In-field imaging doses were measured using various protocols in an anthropomorphic phantom, while out-of-field doses were measured 10 cm from the imaging field edge. Comparison of the CTDI and the in-field doses showed considerable disagreement when the patient anatomy size was not congruent with the size of the CTDI phantom. While that is an expected outcome, this work provides an estimate of the differences for a variety of ClearRT protocols when this situation arises. The CNR was measured for all combinations of ClearRT settings for comparisons within the system, as well as for a comparison with a CBCT and fan-beam CT system. The CNR and dose information provided in this work can be used to aid in selecting a ClearRT imaging protocol. The CT number stability was tracked over 27 months; two instances where the CT number constancy exceeded tolerance were observed after service.</div></div>","PeriodicalId":54397,"journal":{"name":"Zeitschrift fur Medizinische Physik","volume":"36 1","pages":"Pages 60-70"},"PeriodicalIF":4.2,"publicationDate":"2026-02-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143026273","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"医学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2026-02-01DOI: 10.1016/j.zemedi.2025.03.001
Eveline van den Bergh, Iwan Dobbe, Geert J. Streekstra
Four dimensional computed tomography (4D CT) has shown to be of value in the diagnosis of motion related wrist joint pathologies. 4D CT can be performed with a variety of acquisition methods. However, the usability of 4D CT is affected by motion and image artifacts associated with the specific acquisition method used. In this literature review we inventorize which acquisition methods exist for 4D-CT imaging at different positions of the human body and what the advantages and disadvantages of each method are. Based on this assessment we formulate recommendations for the 4D CT imaging approach for diagnosing motion related wrist pathologies. We also address future perspectives of image acquisition in 4D CT of the wrist joint. We found that scanning in volumetric mode eliminates irregularity artifacts, while reducing acquisition time per frame reduces blurring artifacts. A reduced acquisition time can be achieved with short gantry rotation times, dual source CT and Reconstruction based on Partial Gantry Rotation (RPGR). However, the effect of RPGR on RPGR-specific artifacts and the effect of different acquisition times on apparent object displacements may be investigated in future research.
{"title":"4D CT acquisition methods and their anticipated effects on image quality in dynamic CT-scanning of the wrist","authors":"Eveline van den Bergh, Iwan Dobbe, Geert J. Streekstra","doi":"10.1016/j.zemedi.2025.03.001","DOIUrl":"10.1016/j.zemedi.2025.03.001","url":null,"abstract":"<div><div>Four dimensional computed tomography (4D CT) has shown to be of value in the diagnosis of motion related wrist joint pathologies. 4D CT can be performed with a variety of acquisition methods. However, the usability of 4D CT is affected by motion and image artifacts associated with the specific acquisition method used. In this literature review we inventorize which acquisition methods exist for 4D-CT imaging at different positions of the human body and what the advantages and disadvantages of each method are. Based on this assessment we formulate recommendations for the 4D CT imaging approach for diagnosing motion related wrist pathologies. We also address future perspectives of image acquisition in 4D CT of the wrist joint. We found that scanning in volumetric mode eliminates irregularity artifacts, while reducing acquisition time per frame reduces blurring artifacts. A reduced acquisition time can be achieved with short gantry rotation times, dual source CT and Reconstruction based on Partial Gantry Rotation (RPGR). However, the effect of RPGR on RPGR-specific artifacts and the effect of different acquisition times on apparent object displacements may be investigated in future research.</div></div>","PeriodicalId":54397,"journal":{"name":"Zeitschrift fur Medizinische Physik","volume":"36 1","pages":"Pages 5-15"},"PeriodicalIF":4.2,"publicationDate":"2026-02-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144053842","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"医学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2026-02-01DOI: 10.1016/j.zemedi.2024.11.002
Eva Peschke , Mariya S. Pravdivtseva , Olav Jansen , Naomi Larsen , Jan-Bernd Hövener
Vessel walls play a crucial role in many inflammatory vascular diseases. Vessel wall imaging (VWI) using mangnetic resonance imaging (MRI) is one of the few methods by which vessel walls and inflammation can be visualized noninvasively, in vivo, and without ionizing radiation. VWI is based on black-blood (BB) MRI, where the signal from flowing blood is suppressed and contrast agent accumulation in the (inflamed) vessel wall is highlighted. Here, high resolution, T1 weighting, suppression of fat and flowing spins is essential. Whereas VWI is often applied in humans, only very few reports describe its use in small animals.
Here, we investigated whether BB MRI for rodents can be implemented using a state-of-the-art, but commercially available, preclinical MRI system and imaging sequence. We identified 2D spin-echo (RARE)-based BB-MRI as a promising sequence that is widely available and not vendor dependent. First, we investigated the properties of the sequence in vitro with respect to image contrast, resolution, the suppression of signal of flowing spins and fat using a newly developed, 3D-printed model setup (cylindrical model with exchangeable nuclear magnetic resonance tubes and flow tube in agarose, printed with stereolithography). For example, good signal-to-noise ratio, BB and T1 contrast were obtained for TE = 5 ms for slice thickness equal or below 0.352 mm or slice thickness = 0.8 mm with TE at least 25 ms. In vivo, we obtained a pronounced BB effect for both intracranial and abdominal vessels of healthy rats down to a 0.25 mm diameter in no more than 1:36 min with TE = 12 ms, TR = 750 ms, voxel 156 × 156 × 800 µm3, and 11 slices. Compared to in vitro, we were able to reduce TE without apparent artifacts likely because the flow was faster in vivo than in vitro. Additionally, we needed to increase the resolution to image small vessels.
Thus, we found that BB-MRI with 2D spin-echo sequences is feasible on rodents with state-of-the-art, commercially available preclinical MRI systems. We believe that these results will facilitate the development and application of rodent VWI in longitudinal studies, which, in comparison to histology, may reduce the number of needed animals and intersubject variability at the same time.
{"title":"Black-blood MRI at 7T using 2D RARE MRI: In vitro testing and in vivo demonstration","authors":"Eva Peschke , Mariya S. Pravdivtseva , Olav Jansen , Naomi Larsen , Jan-Bernd Hövener","doi":"10.1016/j.zemedi.2024.11.002","DOIUrl":"10.1016/j.zemedi.2024.11.002","url":null,"abstract":"<div><div>Vessel walls play a crucial role in many inflammatory vascular diseases. Vessel wall imaging (VWI) using mangnetic resonance imaging (MRI) is one of the few methods by which vessel walls and inflammation can be visualized noninvasively, in vivo, and without ionizing radiation. VWI is based on black-blood (BB) MRI, where the signal from flowing blood is suppressed and contrast agent accumulation in the (inflamed) vessel wall is highlighted. Here, high resolution, T1 weighting, suppression of fat and flowing spins is essential. Whereas VWI is often applied in humans, only very few reports describe its use in small animals.</div><div>Here, we investigated whether BB MRI for rodents can be implemented using a state-of-the-art, but commercially available, preclinical MRI system and imaging sequence. We identified 2D spin-echo (RARE)-based BB-MRI as a promising sequence that is widely available and not vendor dependent. First, we investigated the properties of the sequence in vitro with respect to image contrast, resolution, the suppression of signal of flowing spins and fat using a newly developed, 3D-printed model setup (cylindrical model with exchangeable nuclear magnetic resonance tubes and flow tube in agarose, printed with stereolithography). For example, good signal-to-noise ratio, BB and T1 contrast were obtained for TE = 5 ms for slice thickness equal or below 0.352 mm or slice thickness = 0.8 mm with TE at least 25 ms. In vivo, we obtained a pronounced BB effect for both intracranial and abdominal vessels of healthy rats down to a 0.25 mm diameter in no more than 1:36 min with TE = 12 ms, TR = 750 ms, voxel 156 × 156 × 800 <em>µ</em>m<sup>3</sup>, and 11 slices. Compared to in vitro, we were able to reduce TE without apparent artifacts likely because the flow was faster in vivo than in vitro. Additionally, we needed to increase the resolution to image small vessels.</div><div>Thus, we found that BB-MRI with 2D spin-echo sequences is feasible on rodents with state-of-the-art, commercially available preclinical MRI systems. We believe that these results will facilitate the development and application of rodent VWI in longitudinal studies, which, in comparison to histology, may reduce the number of needed animals and intersubject variability at the same time.</div></div>","PeriodicalId":54397,"journal":{"name":"Zeitschrift fur Medizinische Physik","volume":"36 1","pages":"Pages 99-113"},"PeriodicalIF":4.2,"publicationDate":"2026-02-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142776194","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"医学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
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