Physica Medica-European Journal of Medical Physics最新文献

Exploring biochemical considerations for diffusive alpha radiation therapy (DaRT) models

IF 3.3 3区医学 Q1 RADIOLOGY, NUCLEAR MEDICINE & MEDICAL IMAGING

Physica Medica-European Journal of Medical Physics

Pub Date : 2025-03-01 DOI: 10.1016/j.ejmp.2025.104947

Peter Dukakis , Jesús J. Bosque , Alejandro Bertolet

Diffusing alpha-emitting Radiation Therapy (DaRT) is a cancer treatment currently undergoing clinical trials. DaRT utilizes localized 224-Radium (²²⁴Ra) seeds to deliver high linear energy transfer (LET) alpha radiation. Its main advantage over other alpha radiation treatments is that the diffusion of ²²⁴Ra decay chain products allows for a more spatially distributed dose. In silico models are used to simulate the physical dynamics of DaRT and the diffusion of DaRT progeny radionuclides into cancer tissue. These models mostly rely on physical principles, often neglecting biochemical interactions with the tumor microenvironment (TME), which affect DaRT dosimetry in human cancer tissue. Here, we address this gap by reviewing how the daughter isotope 212-Lead (²¹²Pb) interacts with chemically heterogeneous TMEs during DaRT treatments. ²¹²Pb is given special attention due to its high physiological activity and long half-life compared to other DaRT radionuclides. By investigating Pb-binding molecules in the TME and their molecular dynamics, we aim to highlight key biochemical processes to be considered by computational models. We identify several species with prevalent roles in cancer tissue as possible binding partners with ²¹²Pb. These species include Glutathione (GSH), Metallothioneins (MTs), Calmodulin (CaM), and Human Serum Albumin (HSA). GSH, MTs, CaM, and HSA were selected based on their known ability to bind to Pb and their concentration in cancer tissue and were examined for their variability in diverse TMEs. Ultimately, this article seeks to guide future research by providing a basic framework of molecular species important for the accurate simulation of DaRT within the TME.

{"title":"Exploring biochemical considerations for diffusive alpha radiation therapy (DaRT) models","authors":"Peter Dukakis , Jesús J. Bosque , Alejandro Bertolet","doi":"10.1016/j.ejmp.2025.104947","DOIUrl":"10.1016/j.ejmp.2025.104947","url":null,"abstract":"<div><div>Diffusing alpha-emitting Radiation Therapy (DaRT) is a cancer treatment currently undergoing clinical trials. DaRT utilizes localized 224-Radium (<sup>224</sup>Ra) seeds to deliver high linear energy transfer (LET) alpha radiation. Its main advantage over other alpha radiation treatments is that the diffusion of <sup>224</sup>Ra decay chain products allows for a more spatially distributed dose. In silico models are used to simulate the physical dynamics of DaRT and the diffusion of DaRT progeny radionuclides into cancer tissue. These models mostly rely on physical principles, often neglecting biochemical interactions with the tumor microenvironment (TME), which affect DaRT dosimetry in human cancer tissue. Here, we address this gap by reviewing how the daughter isotope 212-Lead (<sup>212</sup>Pb) interacts with chemically heterogeneous TMEs during DaRT treatments. <sup>212</sup>Pb is given special attention due to its high physiological activity and long half-life compared to other DaRT radionuclides. By investigating Pb-binding molecules in the TME and their molecular dynamics, we aim to highlight key biochemical processes to be considered by computational models. We identify several species with prevalent roles in cancer tissue as possible binding partners with <sup>212</sup>Pb. These species include Glutathione (GSH), Metallothioneins (MTs), Calmodulin (CaM), and Human Serum Albumin (HSA). GSH, MTs, CaM, and HSA were selected based on their known ability to bind to Pb and their concentration in cancer tissue and were examined for their variability in diverse TMEs. Ultimately, this article seeks to guide future research by providing a basic framework of molecular species important for the accurate simulation of DaRT within the TME.</div></div>","PeriodicalId":56092,"journal":{"name":"Physica Medica-European Journal of Medical Physics","volume":"131 ","pages":"Article 104947"},"PeriodicalIF":3.3,"publicationDate":"2025-03-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143512694","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}

引用次数: 0

Experience and uncertainty analysis of CT-based adaptive radiotherapy for abdominal treatments

IF 3.3 3区医学 Q1 RADIOLOGY, NUCLEAR MEDICINE & MEDICAL IMAGING

Physica Medica-European Journal of Medical Physics

Pub Date : 2025-03-01 DOI: 10.1016/j.ejmp.2025.104946

J.V. Panetta, A. Eldib, J.E. Meyer, T.J. Galloway, E.M. Horwitz, C.M.C. Ma

Background

Online adaptive radiotherapy (ART) allows for daily replanning of treatment plans with adjustments according to current day anatomy. The purpose of this work is to present our methodology for using CT-based ART applied to abdominal cases along with our experience with this treatment. We additionally aim to estimate some of the uncertainties associated with the adaptive process.

Methods and Materials

Analysis was performed on patients with abdominal targets (N = 41, 205 fractions), treated on a CT-based adaptive treatment unit; treatment sites were divided into 3 categories: pancreas, liver, and other (e.g., lymph nodes). Statistics regarding contouring time, planning target volume (PTV) coverage, and organ-at-risk (OAR) sparing are presented. Contouring uncertainty was estimated by expanding critical OARs and recalculating dose, and auto-registration uncertainty was estimated by adjusting the registration between the cone beam computed tomography scan and the dose cloud and recalculating dose.

Results

Coverage for the planning optimization PTV (PTV_Opt) for adaptive plans was on average 94.7 ± 0.4 %, while for scheduled plans it was on average 92.0 ± 0.6 %. The average decrease in OAR maximum dose by using the adaptive plans was 11.6 ± 1.0 %. Contouring time was on average 23 ± 0 min. Uncertainty estimates for PTV V100% were on average 0.6 ± 0.4 %; combined uncertainties for maximum OAR dose were on average 4.6 ± 0.4 %.

Conclusion

Adaptive therapy on average led to plans with improved PTV coverage or OAR sparing, and our workflow allowed for treatment to be completed within a reasonable timeframe. The benefit of adaptive therapy largely outweighed estimates of uncertainty.

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引用次数: 0

Monte Carlo calculated beam quality correction factors for high energy photon and electron fields

IF 3.3 3区医学 Q1 RADIOLOGY, NUCLEAR MEDICINE & MEDICAL IMAGING

Physica Medica-European Journal of Medical Physics

Pub Date : 2025-03-01 DOI: 10.1016/j.ejmp.2025.104939

Damian Czarnecki , Klemens Zink

Purpose:

Although several studies provide data on reference dosimetry, ionization chambers are in clinical use worldwide, for which no or only a few correction factors for beam quality are available. The aim of this study was to calculate beam quality correction factors in electron and photon fields for four cylindrical ionization chamber, i.e. CC08, CC04, Razor™ Chamber and Razor™ Nano Chamber (all IBA, Dosimetry, Schwarzenbruck, Germany).

Method:

Monte Carlo simulations were performed with the EGSnrc code system to calculate the beam quality correction factor

k_{Q}

. Therefore, a detailed Monte Carlo based model of the four ionization chambers were created to calculate the dose in the sensitive volume. Electron and photon spectra of clinical linear accelerators within the entire energy range of therapeutic linear accelerators were used as radiation source.

Results:

k_{Q}

values as a function of the beam quality specifiers TPR

_{20, 10}

and

R_{50}

were calculated for high energy photon and electron fields, respectively. The data was fitted against recommended equations for photon and electron dosimetry with a

χ^{2}

between 6.4e−7 and 4.2e−6.

Conclusion:

Electron and photon beam quality correction factors

k_{Q}

were calculated by Monte Carlo simulations for the cylindrical ionization chambers CC08, CC04, Razor™ Chamber and Razor™ Nano Chamber to provide

k_{Q}

values for absolute dosimetry according to the TRS 398 dosimetry protocol.

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引用次数: 0

All-Ireland evaluation of ultrasound systems for prostate brachytherapy: Application specific quality control protocol and quality assurance phantoms

IF 3.3 3区医学 Q1 RADIOLOGY, NUCLEAR MEDICINE & MEDICAL IMAGING

Physica Medica-European Journal of Medical Physics

Pub Date : 2025-02-26 DOI: 10.1016/j.ejmp.2025.104934

Andrea J. Doyle , Deidre M. King , Dervil Cody , Aoife M. Ivory , Jacinta E. Browne

Context

The goal of quality assurance (QA) for transrectal ultrasound (TRUS) prostate brachytherapy is to ensure optimum patient outcomes by providing a high-quality service using equipment that is operating at optimum performance levels. There are specific recommendations from professional organisations that outline the QA parameters that need to be considered specifically for ultrasound guided prostate brachytherapy. However, these recommendations are heavily based on the guidance made for the general application of ultrasound to all relevant clinical applications.

Additionally, there is a lack of consensus on the optimum QA test device to conduct the schedule of testing for this specific application of TRUS image guided interventional procedures.

Procedures

In this study, we describe a task-specific testing schedule for TRUS QA, detailing the QA test protocol, and the recommended equipment set-up, and scan parameters to evaluate these systems. Also described are the commercially available test devices, as well as custom made devices including the design and acoustic characteristics of the materials used to design the custom devices. This QA test protocol was used to evaluate nine TRUS systems used on the island of Ireland in prostate brachytherapy treatment.

Main Findings

The evaluation revealed significant differences among the nine TRUS scanners, highlighting variations in manufacturer pre-sets and their potential limitations in effectively guiding prostate brachytherapy.

Conclusion

This study highlights the urgent need for application specific QA test devices for TRUS systems used to guide prostate brachytherapy, and the need for the optimization of scanning parameters during these procedures.

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引用次数: 0

Erratum to "Stability of radiomic features in magnetic resonance imaging of the female pelvis: A multicentre phantom study" [Phys. Medica 130 (2025) 104895].

IF 3.3 3区医学 Q1 RADIOLOGY, NUCLEAR MEDICINE & MEDICAL IMAGING

Physica Medica-European Journal of Medical Physics

Pub Date : 2025-02-25 DOI: 10.1016/j.ejmp.2025.104948

Roberto Sghedoni, Daniela Origgi, Noemi Cucurachi, Giuseppe Castiglioni Minischetti, Davide Alio, Giovanni Savini, Francesca Botta, Simona Marzi, Marco Aiello, Tiziana Rancati, Davide Cusumano, Letterio Salvatore Politi, Vittorio Didonna, Raffaella Massafra, Antonella Petrillo, Antonio Esposito, Sara Imparato, Luca Anemoni, Chandra Bortolotto, Lorenzo Preda, Luca Boldrini

引用次数: 0

Breast density prediction model in digital versus synthetic mammograms from a radiomic point of view: A retrospective study 从放射线学角度看数字与合成乳房 X 光照片的乳房密度预测模型：回顾性研究

IF 3.3 3区医学 Q1 RADIOLOGY, NUCLEAR MEDICINE & MEDICAL IMAGING

Physica Medica-European Journal of Medical Physics

Pub Date : 2025-02-24 DOI: 10.1016/j.ejmp.2025.104942

E. Loi , G. Feliciani , M. Amadori , A. Bettinelli , F. Marturano , I. Azzali , E. Mezzenga , P.A. Sanna , D. Severi , S. Rivetti , M. Paiusco , G. Martinelli , A. Sarnelli , F. Falcini

Purpose

In this retrospective study, we develop radiomics prediction models from synthetic mammograms(SM) and digital mammograms(DM) images to identify which imaging modality has the most predictive power when employed for prediction of breast density.

Methods

Patients aged between 45 and 74 years, were included in the study. For each, a SM in standard resolution (ST) and High Resolution (HR) were obtained, and a 150 x 150 pixels square area was defined on the images to be used for texture analysis of the breast parenchyma. A semi-automated placing strategy was used to reduce user reliance on the segmentation location. S-IBEX software was employed to extract radiomics features. Feature robustness analysis was also done to ensure model reproducibility. The Least Absolute Shrinkage and Selection Operator(LASSO) logistic regression model was trained to predict dichotomized breast density according to BIRADS classification model performance was assessed through receiver operating curves (ROC) for DM, HR, and ST.

Results

We extracted 123 features from the 10 ROIs of 96 patient. After robustness analysis, the most predictive features were employed to build logistic regression-based models.

The average performance of the models were 0.74, 0.67, and 0.64 on DM, HR, and ST, respectively, suggesting that DM maintains the highest informative content on breast density.

Conclusions

This study investigated how well radiomics models trained on various imaging modalities predicted breast density. Our results may be pertinent to the debate over screening mammography technique optimization using quantitative measures based on radiomics features.

{"title":"Breast density prediction model in digital versus synthetic mammograms from a radiomic point of view: A retrospective study","authors":"E. Loi , G. Feliciani , M. Amadori , A. Bettinelli , F. Marturano , I. Azzali , E. Mezzenga , P.A. Sanna , D. Severi , S. Rivetti , M. Paiusco , G. Martinelli , A. Sarnelli , F. Falcini","doi":"10.1016/j.ejmp.2025.104942","DOIUrl":"10.1016/j.ejmp.2025.104942","url":null,"abstract":"<div><h3>Purpose</h3><div>In this retrospective study, we develop radiomics prediction models from synthetic mammograms(SM) and digital mammograms(DM) images to identify which imaging modality has the most predictive power when employed for prediction of breast density.</div></div><div><h3>Methods</h3><div>Patients aged between 45 and 74 years, were included in the study. For each, a SM in standard resolution (ST) and High Resolution (HR) were obtained, and a 150 x 150 pixels square area was defined on the images to be used for texture analysis of the breast parenchyma. A semi-automated placing strategy was used to reduce user reliance on the segmentation location. S-IBEX software was employed to extract radiomics features. Feature robustness analysis was also done to ensure model reproducibility. The Least Absolute Shrinkage and Selection Operator(LASSO) logistic regression model was trained to predict dichotomized breast density according to BIRADS classification model performance was assessed through receiver operating curves (ROC) for DM, HR, and ST.</div></div><div><h3>Results</h3><div>We extracted 123 features from the 10 ROIs of 96 patient. After robustness analysis, the most predictive features were employed to build logistic regression-based models.</div><div>The average performance of the models were 0.74, 0.67, and 0.64 on DM, HR, and ST, respectively, suggesting that DM maintains the highest informative content on breast density.</div></div><div><h3>Conclusions</h3><div>This study investigated how well radiomics models trained on various imaging modalities predicted breast density. Our results may be pertinent to the debate over screening mammography technique optimization using quantitative measures based on radiomics features.</div></div>","PeriodicalId":56092,"journal":{"name":"Physica Medica-European Journal of Medical Physics","volume":"131 ","pages":"Article 104942"},"PeriodicalIF":3.3,"publicationDate":"2025-02-24","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143474470","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"医学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 0

Development of a cerebral CT perfusion phantom: A structured approach

IF 3.3 3区医学 Q1 RADIOLOGY, NUCLEAR MEDICINE & MEDICAL IMAGING

Physica Medica-European Journal of Medical Physics

Pub Date : 2025-02-21 DOI: 10.1016/j.ejmp.2025.104944

Liselot C. Goris , Abdallah H.A. Zaid Al-Kaylani , Richte C.L. Schuurmann , Marcel J.W. Greuter , Reinoud P.H. Bokkers , Srirang Manohar

Introduction

Computed tomography perfusion (CTP) imaging is crucial in diagnosing and managing vascular diseases, e.g, stroke. Differences in scanners and protocols may lead to different results, affecting clinical decision-making. Objective validation and evaluation of CTP imaging are therefore important. Perfusion phantoms are essential test objects to facilitate the validation and evaluation of perfusion imaging. Therefore, this study aimed to develop, validate and evaluate a brain perfusion phantom for the evaluation of cerebral CTP.

Methods

A cerebral perfusion phantom was developed to evaluate CTP imaging of the brain using a workflow based on the Design Science Research Methodology. The reliability and repeatability of the phantom’s perfusion parameters derived from the time-density curves (TDCs) in CTP were evaluated.

Results

A 3D-printed modular perfusion phantom was developed, filled with sodium alginate beads, and connected to a pumping system to mimic microvasculature and flow dynamics. The phantom consisted of three compartments that simulated different states of perfusion. The phantom showed reliable TDCs, with a relative standard deviation of <6.6 % for peak intensity and time-to-peak (TTP) over two sets of five repeated experiments for all compartments, and repeatable TTP and mean transit time values with a repeatability coefficient of <2.3 s compared to the mean.

Conclusions

The developed perfusion phantom demonstrated high reliability and could be employed for investigating CTP imaging under various flow speeds. The presented workflow promotes transparency in the development, validation, and application of CTP phantoms, and facilitates cross-study comparisons through structured iterative development and unified evaluation metrics.

{"title":"Development of a cerebral CT perfusion phantom: A structured approach","authors":"Liselot C. Goris , Abdallah H.A. Zaid Al-Kaylani , Richte C.L. Schuurmann , Marcel J.W. Greuter , Reinoud P.H. Bokkers , Srirang Manohar","doi":"10.1016/j.ejmp.2025.104944","DOIUrl":"10.1016/j.ejmp.2025.104944","url":null,"abstract":"<div><h3>Introduction</h3><div>Computed tomography perfusion (CTP) imaging is crucial in diagnosing and managing vascular diseases, e.g, stroke. Differences in scanners and protocols may lead to different results, affecting clinical decision-making. Objective validation and evaluation of CTP imaging are therefore important. Perfusion phantoms are essential test objects to facilitate the validation and evaluation of perfusion imaging. Therefore, this study aimed to develop, validate and evaluate a brain perfusion phantom for the evaluation of cerebral CTP.</div></div><div><h3>Methods</h3><div>A cerebral perfusion phantom was developed to evaluate CTP imaging of the brain using a workflow based on the Design Science Research Methodology. The reliability and repeatability of the phantom’s perfusion parameters derived from the time-density curves (TDCs) in CTP were evaluated.</div></div><div><h3>Results</h3><div>A 3D-printed modular perfusion phantom was developed, filled with sodium alginate beads, and connected to a pumping system to mimic microvasculature and flow dynamics. The phantom consisted of three compartments that simulated different states of perfusion. The phantom showed reliable TDCs, with a relative standard deviation of <6.6 % for peak intensity and time-to-peak (TTP) over two sets of five repeated experiments for all compartments, and repeatable TTP and mean transit time values with a repeatability coefficient of <2.3 s compared to the mean.</div></div><div><h3>Conclusions</h3><div>The developed perfusion phantom demonstrated high reliability and could be employed for investigating CTP imaging under various flow speeds. The presented workflow promotes transparency in the development, validation, and application of CTP phantoms, and facilitates cross-study comparisons through structured iterative development and unified evaluation metrics.</div></div>","PeriodicalId":56092,"journal":{"name":"Physica Medica-European Journal of Medical Physics","volume":"131 ","pages":"Article 104944"},"PeriodicalIF":3.3,"publicationDate":"2025-02-21","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143454468","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"医学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 0

Accuracy and consistency of effective atomic number over object size using deep silicon photon-counting detector CT

IF 3.3 3区医学 Q1 RADIOLOGY, NUCLEAR MEDICINE & MEDICAL IMAGING

Physica Medica-European Journal of Medical Physics

Pub Date : 2025-02-21 DOI: 10.1016/j.ejmp.2025.104945

Teva N. Shapiro , Aria M. Salyapongse , Meghan G. Lubner , Giuseppe V. Toia , Zhye Yin , Scott Slavic , Timothy P. Szczykutowicz

Purpose

Photon-counting detector (PCD) CT is the newest generation of CT detector technology. It is critical to characterize its performance in measuring important biomarkers used in quantitative CT including effective atomic number (Z_eff). More accurate Z_eff measurements could be beneficial in tissue classification and proton therapy tasks.

Methods

A phantom of varying water-equivalent diameter (WED) containing clinically relevant inserts was scanned using a prototype deep silicon PCD CT and a dual-energy (DE) energy integrating detector (EID) CT. Z_eff maps were generated. Measured Z_eff values were compared across WEDs and to theoretical values.

Results

The measured Z_eff of the polystyrene, solid water, iodine, and bone (50% CaCO3) inserts differed from the theoretical value by a maximum of −14.0%, 4.6%, 8.4% and 13.0% respectively on EID vs 4.5%, 5.2%, 2.3% and 7.2% on PCD. The maximum variation in Z_eff over the WED range on EID was 0.71, 0.27, 0.66, and 1.22 vs 0.47, 0.64, 0.1 and 0.22 on PCD for polystyrene, solid water, iodine, and bone (50% CaCO3) respectively.

Conclusion

This is the first study to evaluate Z_eff measurements made using a prototype whole body PCD CT system. We found that PCD CT outperformed the EID CT in terms of Z_eff accuracy and consistency over the WED range on most of the insert materials. Similarly, PCD CT outperformed most previous study’s findings using EID CT. The high consistency and accuracy of measured Z_eff using deep silicon PCD CT could make quantitative CT increasingly possible over a large range of patient sizes.

{"title":"Accuracy and consistency of effective atomic number over object size using deep silicon photon-counting detector CT","authors":"Teva N. Shapiro , Aria M. Salyapongse , Meghan G. Lubner , Giuseppe V. Toia , Zhye Yin , Scott Slavic , Timothy P. Szczykutowicz","doi":"10.1016/j.ejmp.2025.104945","DOIUrl":"10.1016/j.ejmp.2025.104945","url":null,"abstract":"<div><h3>Purpose</h3><div>Photon-counting detector (PCD) CT is the newest generation of CT detector technology. It is critical to characterize its performance in measuring important biomarkers used in quantitative CT including effective atomic number (Z<sub>eff</sub>). More accurate Z<sub>eff</sub> measurements could be beneficial in tissue classification and proton therapy tasks.</div></div><div><h3>Methods</h3><div>A phantom of varying water-equivalent diameter (WED) containing clinically relevant inserts was scanned using a prototype deep silicon PCD CT and a dual-energy (DE) energy integrating detector (EID) CT. Z<sub>eff</sub> maps were generated. Measured Z<sub>eff</sub> values were compared across WEDs and to theoretical values.</div></div><div><h3>Results</h3><div>The measured Z<sub>eff</sub> of the polystyrene, solid water, iodine, and bone (50% CaCO3) inserts differed from the theoretical value by a maximum of −14.0%, 4.6%, 8.4% and 13.0% respectively on EID vs 4.5%, 5.2%, 2.3% and 7.2% on PCD. The maximum variation in Z<sub>eff</sub> over the WED range on EID was 0.71, 0.27, 0.66, and 1.22 vs 0.47, 0.64, 0.1 and 0.22 on PCD for polystyrene, solid water, iodine, and bone (50% CaCO3) respectively.</div></div><div><h3>Conclusion</h3><div>This is the first study to evaluate Z<sub>eff</sub> measurements made using a prototype whole body PCD CT system. We found that PCD CT outperformed the EID CT in terms of Z<sub>eff</sub> accuracy and consistency over the WED range on most of the insert materials. Similarly, PCD CT outperformed most previous study’s findings using EID CT. The high consistency and accuracy of measured Z<sub>eff</sub> using deep silicon PCD CT could make quantitative CT increasingly possible over a large range of patient sizes.</div></div>","PeriodicalId":56092,"journal":{"name":"Physica Medica-European Journal of Medical Physics","volume":"131 ","pages":"Article 104945"},"PeriodicalIF":3.3,"publicationDate":"2025-02-21","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143464173","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"医学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 0

Cone beam CT (CBCT) in radiotherapy: Assessment of doses using a pragmatic setup in an international setting

IF 3.3 3区医学 Q1 RADIOLOGY, NUCLEAR MEDICINE & MEDICAL IMAGING

Physica Medica-European Journal of Medical Physics

Pub Date : 2025-02-21 DOI: 10.1016/j.ejmp.2025.104937

Mario Djukelic , Colin John Martin , Abdullah Abuhaimed , Tomas Kron , Sebastien Gros , Tim Wood , Piotr Pankowski , Ngie Min Ung , Jenia Vassileva , María Cristina Plazas , Snezana Vostinic , Anja Lazovic , Ana Cravo Sá , Isabelle Nilsson , Marianna Koutrouli , Lavanya Murugan , Hein Fourie , Aliaksandr Miadzvetski , Buthaina Al Ameri , Mirta Dumancic , William Small Jr.

Introduction

The imaging modality kV CBCT on linear accelerators (linacs) is utilised to verify positioning and anatomy in cancer patients undergoing radiotherapy treatment. There is a need for optimisation of radiological protection in kV CBCT imaging protocols to avoid unnecessarily high exposures to normal tissues surrounding the target.

Methods

A network of ICRP mentees from 23 countries were surveyed for available dosimetry equipment. Standardised measurements on CBCT linac imaging systems were conducted using a cone beam dose index (CBDI) devised as a straightforward measurement for wide beam doses. Measurements were made with (a) 100 mm ionisation chambers or (b) 0.6 cc Farmer ionisation chambers and cylindrical CT PMMA phantoms, and (c) an alternative setup of Farmer chambers and cubical phantoms comprised of slabs of water equivalent material readily available in radiotherapy centres. The measurements were compared with Monte Carlo (MC) simulations.

Results

The survey showed limited availability for the reference setup using 100 mm chambers and CT phantoms. Correction factors were derived to convert normalised CBDI from alternative setups to the reference setup and are on average within 2% of MC simulations.

Conclusion

The slab phantom in combination with a Farmer chamber provides an alternative to quantify CBCT radiation dose indices from linac-based image-guided radiotherapy using materials accessible in most centres worldwide. A method is presented to use correction factors for Varian Truebeam linacs if traditional 100 mm chambers and cylindrical CT phantoms are not available. This will enable most radiotherapy centres across the world to engage in meaningful imaging dose measurement and optimisation.

{"title":"Cone beam CT (CBCT) in radiotherapy: Assessment of doses using a pragmatic setup in an international setting","authors":"Mario Djukelic , Colin John Martin , Abdullah Abuhaimed , Tomas Kron , Sebastien Gros , Tim Wood , Piotr Pankowski , Ngie Min Ung , Jenia Vassileva , María Cristina Plazas , Snezana Vostinic , Anja Lazovic , Ana Cravo Sá , Isabelle Nilsson , Marianna Koutrouli , Lavanya Murugan , Hein Fourie , Aliaksandr Miadzvetski , Buthaina Al Ameri , Mirta Dumancic , William Small Jr.","doi":"10.1016/j.ejmp.2025.104937","DOIUrl":"10.1016/j.ejmp.2025.104937","url":null,"abstract":"<div><h3>Introduction</h3><div>The imaging modality kV CBCT on linear accelerators (linacs) is utilised to verify positioning and anatomy in cancer patients undergoing radiotherapy treatment. There is a need for optimisation of radiological protection in kV CBCT imaging protocols to avoid unnecessarily high exposures to normal tissues surrounding the target.</div></div><div><h3>Methods</h3><div>A network of ICRP mentees from 23 countries were surveyed for available dosimetry equipment. Standardised measurements on CBCT linac imaging systems were conducted using a cone beam dose index (CBDI) devised as a straightforward measurement for wide beam doses. Measurements were made with (a) 100 mm ionisation chambers or (b) 0.6 cc Farmer ionisation chambers and cylindrical CT PMMA phantoms, and (c) an alternative setup of Farmer chambers and cubical phantoms comprised of slabs of water equivalent material readily available in radiotherapy centres. The measurements were compared with Monte Carlo (MC) simulations.</div></div><div><h3>Results</h3><div>The survey showed limited availability for the reference setup using 100 mm chambers and CT phantoms. Correction factors were derived to convert normalised CBDI from alternative setups to the reference setup and are on average within 2% of MC simulations.</div></div><div><h3>Conclusion</h3><div>The slab phantom in combination with a Farmer chamber provides an alternative to quantify CBCT radiation dose indices from linac-based image-guided radiotherapy using materials accessible in most centres worldwide. A method is presented to use correction factors for Varian Truebeam linacs if traditional 100 mm chambers and cylindrical CT phantoms are not available. This will enable most radiotherapy centres across the world to engage in meaningful imaging dose measurement and optimisation.</div></div>","PeriodicalId":56092,"journal":{"name":"Physica Medica-European Journal of Medical Physics","volume":"131 ","pages":"Article 104937"},"PeriodicalIF":3.3,"publicationDate":"2025-02-21","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143464172","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}

引用次数: 0

Implementation of Linac-based VMAT total body irradiation technique on Elekta platform using surface-guided radiation therapy

IF 3.3 3区医学 Q1 RADIOLOGY, NUCLEAR MEDICINE & MEDICAL IMAGING

Physica Medica-European Journal of Medical Physics

Pub Date : 2025-02-20 DOI: 10.1016/j.ejmp.2025.104940

Magali Sandt , Stéphanie Marcet , Nathalie Guesnel , Line Claude , Isabelle Martel , Marie-Claude Biston

Background/introduction

To present an optimal workflow using a rotatable tabletop and a surface guided radiation therapy (SGRT) system for volumetric modulated arc therapy (VMAT) based total-body irradiation (TBI).

Methods

Twenty patients having received either 2 Gy, 8 Gy, or 12 Gy in 2 Gy per fraction were included. They were immobilized using a vacuum cushion and a three-points mask and positioned on a rotatable tabletop. VMAT treatment plans were performed on Monaco 6.1 (Elekta LTD, Stockholm) treatment planning system and then perturbed by applying shifts of 5mm on the isocenters coordinates to evaluate the robustness. Patients were treated on a Synergy or a VersaHD (Elekta LTD, Stockholm) Linac. Pretreatment positioning was performed either with cone-beam CT images combined with surface guided radiation therapy (SGRT) or with SGRT only. During treatment, intra-fraction motion was controlled with SGRT. Dosimetric data, robustness results and sessions duration were collected.

Results

In terms of PTV coverage and lung-sparing, all plans met the requirements of the most recent recommendations. The use of 20–30 cm distances between isocenters, and a 90° collimator rotation, enabled to obtain a linear dose gradient between two consecutive beams, which ensured sufficient robustness against 5 mm shifts in isocenter coordinates in all directions. With an average duration of 1 h ± 12 min between the first and last beams, the first sessions were comparable in length to the extended source-to-skin distance technique.

Conclusion

Thanks to the rotatable tabletop and to the SGRT system, accurate and secured VMAT-based TBI treatments were performed within a reasonable timeframe, while ensuring patient comfort.

{"title":"Implementation of Linac-based VMAT total body irradiation technique on Elekta platform using surface-guided radiation therapy","authors":"Magali Sandt , Stéphanie Marcet , Nathalie Guesnel , Line Claude , Isabelle Martel , Marie-Claude Biston","doi":"10.1016/j.ejmp.2025.104940","DOIUrl":"10.1016/j.ejmp.2025.104940","url":null,"abstract":"<div><h3>Background/introduction</h3><div>To present an optimal workflow using a rotatable tabletop and a surface guided radiation therapy (SGRT) system for volumetric modulated arc therapy (VMAT) based total-body irradiation (TBI).</div></div><div><h3>Methods</h3><div>Twenty patients having received either 2 Gy, 8 Gy, or 12 Gy in 2 Gy per fraction were included. They were immobilized using a vacuum cushion and a three-points mask and positioned on a rotatable tabletop. VMAT treatment plans were performed on Monaco 6.1 (Elekta LTD, Stockholm) treatment planning system and then perturbed by applying shifts of 5mm on the isocenters coordinates to evaluate the robustness. Patients were treated on a Synergy or a VersaHD (Elekta LTD, Stockholm) Linac. Pretreatment positioning was performed either with cone-beam CT images combined with surface guided radiation therapy (SGRT) or with SGRT only. During treatment, intra-fraction motion was controlled with SGRT. Dosimetric data, robustness results and sessions duration were collected.</div></div><div><h3>Results</h3><div>In terms of PTV coverage and lung-sparing, all plans met the requirements of the most recent recommendations. The use of 20–30 cm distances between isocenters, and a 90° collimator rotation, enabled to obtain a linear dose gradient between two consecutive beams, which ensured sufficient robustness against 5 mm shifts in isocenter coordinates in all directions. With an average duration of 1 h ± 12 min between the first and last beams, the first sessions were comparable in length to the extended source-to-skin distance technique.</div></div><div><h3>Conclusion</h3><div>Thanks to the rotatable tabletop and to the SGRT system, accurate and secured VMAT-based TBI treatments were performed within a reasonable timeframe, while ensuring patient comfort.</div></div>","PeriodicalId":56092,"journal":{"name":"Physica Medica-European Journal of Medical Physics","volume":"131 ","pages":"Article 104940"},"PeriodicalIF":3.3,"publicationDate":"2025-02-20","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143444655","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"医学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 0