The effects of patient positioning when interpreting CT dose metrics: A phantom study

2017 ◽  
Vol 44 (4) ◽  
pp. 1514-1524 ◽  
Author(s):  
Rebecca M. Marsh ◽  
Michael S. Silosky
Keyword(s):  
Patient Positioning ◽  
Phantom Study ◽  
Ct Dose ◽  
Dose Metrics

scholarly journals Tumor Response Prediction in 90Y Radioembolization with PET-based Radiomics Features and Absorbed Dose Metrics

2020 ◽  
Author(s):  
Lise Wei ◽  
Can Cui ◽  
Jiarui Xu ◽  
Ravi Kaza ◽  
Issam El Naqa ◽  
...  
Keyword(s):  
Cross Validation ◽  
Cox Regression ◽  
Optimal Parameter ◽  
Absorbed Dose ◽  
Phantom Study ◽  
Operating Characteristics ◽  
Liver Malignancies ◽  
Progression Model ◽  
Dose Metrics ◽  
Combined Models

Abstract Purpose Evaluate whether lesion radiomics features and absorbed dose metrics extracted from post-therapy 90 Y PET can be integrated to better predict outcome in microsphere radioembolization of liver malignancies. Methods Given the noisy nature of 90 Y PET, first, a liver phantom study with repeated acquisitions and varying reconstruction parameters was used to identify a subset of robust radiomics features for the patient analysis. In 36 radioembolization procedures, 90 Y PET/CT was performed within a couple of hours to extract 46 radiomics features and estimate absorbed dose in 105 primary and metastatic liver lesions. Robust radiomics modeling was based on bootstrapped multivariate logistic regression with shrinkage regularization (LASSO) and Cox regression with LASSO. Nested cross-validation and bootstrap resampling were used for optimal parameter/feature selection and for guarding against overfitting risks. Spearman rank correlation was used to analyze feature associations. Area under the receiver-operating characteristics curve (AUC) was used for lesion response (at first follow-up) analysis while Kaplan-Meier plots and c-index were used to assess progression model performance. Models with absorbed dose only, radiomics only and combined models were developed to predict lesion outcome. Results The phantom study identified 15/46 reproducible and robust radiomics features that were subsequently used in the patient models. A lesion response model with zone percentage (ZP) and mean absorbed dose achieved an AUC of 0.729 (95%CI: 0.702-0.758) and a progression model with zone size nonuniformity (ZSN) and absorbed dose achieved a c-index of 0.803 (95% CI: 0.790-0.815) on nested cross validation (CV). The combined models outperformed the radiomics only and absorbed dose only models. Conclusion We have developed new lesion-level response and progression models using textural radiomics features, derived from 90 Y PET combined with mean absorbed dose for predicting outcome in radioembolization. These encouraging results may need further validation in independent datasets prior to clinical adoption.

scholarly journals Reducing dose of Cone-Beam CT used for patient positioning in radiooncology

2021 ◽  
Vol 7 (2) ◽  
pp. 227-230
Author(s):  
Verena Gorges ◽  
Waldemar Zylka
Keyword(s):  
Dose Reduction ◽  
Cone Beam Ct ◽  
Patient Positioning ◽  
Cone Beam ◽  
Thoracic Region ◽  
Analysis Software ◽  
Tumor Patients ◽  
Ct Dose ◽  
Full Rotation ◽  
Ct Dose Index

Abstract Cone-Beam computed tomography (CBCT) has become the most important component of modern radiotherapy for positioning tumor patients directly before treatment. In this work we investigate alternations to standard acquisition protocol, called preset, for patients with a tumor in the thoracic region. The effects of the changed acquisition parameters on the image quality are evaluated using the Catphan Phantom and the image analysis software Smári. The weighted CT dose index (CTDIW) is determined in each case and the effects of the different acquisition protocols on the patient dose are classified accordingly. Additionally, the clinical suitability of alternative presets is tested by investigating correctness of image registration using the CIRS thorax phantom. The results show that a significant dose reduction can be achieved. It can be reduced by 51% for a full rotation by adjusting the gantry speed. A more patientspecific uptake protocol for patients with laterally located tumor was created which allows a dose reduction of 54%.

scholarly journals CT dose optimization for the detection of pulmonary arteriovenous malformation (PAVM): A phantom study

2020 ◽  
Vol 101 (5) ◽  
pp. 289-297 ◽  
Author(s):  
J. Greffier ◽  
S. Boccalini ◽  
J.P. Beregi ◽  
A. Vlassenbroek ◽  
A. Vuillod ◽  
...  
Keyword(s):  
Arteriovenous Malformation ◽  
Phantom Study ◽  
Pulmonary Arteriovenous Malformation ◽  
Dose Optimization ◽  
Ct Dose

scholarly journals Tumor Response Prediction in 90Y Radioembolization with PET-based Radiomics Features and Absorbed Dose Metrics

2020 ◽  
Author(s):  
Lise Wei ◽  
Can Cui ◽  
Jiarui Xu ◽  
Ravi Kaza ◽  
Issam El Naqa ◽  
...  
Keyword(s):  
Cross Validation ◽  
Cox Regression ◽  
Optimal Parameter ◽  
Absorbed Dose ◽  
Phantom Study ◽  
Operating Characteristics ◽  
Liver Malignancies ◽  
Progression Model ◽  
Dose Metrics ◽  
Combined Models

Abstract Purpose Evaluate whether lesion radiomics features and absorbed dose metrics extracted from post-therapy 90Y PET can be integrated to better predict outcome in microsphere radioembolization of liver malignancies. Methods Given the noisy nature of 90Y PET, first, a liver phantom study with repeated acquisitions and varying reconstruction parameters was used to identify a subset of robust radiomics features for the patient analysis. In 36 radioembolization procedures, 90Y PET/CT was performed within a couple of hours to extract 46 radiomics features and estimate absorbed dose in 105 primary and metastatic liver lesions. Robust radiomics modeling was based on bootstrapped multivariate logistic regression with shrinkage regularization (LASSO) and Cox regression with LASSO. Nested cross-validation and bootstrap resampling were used for optimal parameter/feature selection and for guarding against overfitting risks. Spearman rank correlation was used to analyze feature associations. Area under the receiver-operating characteristics curve (AUC) was used for lesion response (at first follow-up) analysis while Kaplan-Meier plots and c-index were used to assess progression model performance. Models with absorbed dose only, radiomics only and combined models were developed to predict lesion outcome.Results The phantom study identified 15/46 reproducible and robust radiomics features that were subsequently used in the patient models. A lesion response model with zone percentage (ZP) and mean absorbed dose achieved an AUC of 0.729 (95%CI: 0.702-0.758) and a progression model with zone size nonuniformity (ZSN) and absorbed dose achieved a c-index of 0.803 (95% CI: 0.790-0.815) on nested cross validation (CV). The combined models outperformed the radiomics only and absorbed dose only models.Conclusion We have developed new lesion-level response and progression models using textural radiomics features, derived from 90Y PET combined with mean absorbed dose for predicting outcome in radioembolization. These encouraging results may need further validation in independent datasets prior to clinical adoption.

scholarly journals Tumor Response Prediction in 90Y Radioembolization with PET-based Radiomics Features and Absorbed Dose Metrics

2020 ◽  
Author(s):  
Lise Wei ◽  
Can Cui ◽  
Jiarui Xu ◽  
Ravi Kaza ◽  
Issam El Naqa ◽  
...  
Keyword(s):  
Cross Validation ◽  
Cox Regression ◽  
Statistical Significance ◽  
Absorbed Dose ◽  
Phantom Study ◽  
Operating Characteristics ◽  
Data Set ◽  
Progression Model ◽  
Dose Metrics ◽  
Combined Models

Abstract Purpose Evaluate whether lesion radiomics features and absorbed dose metrics extracted from post-therapy 90Y PET can be integrated to better predict outcome in microsphere radioembolization of liver malignancies. Methods Given the noisy nature of 90Y PET, first, a liver phantom study with repeated acquisitions and varying reconstruction parameters was used to identify a subset of robust radiomics features for the patient analysis. In 36 radioembolization procedures, 90Y PET/CT was performed within a couple of hours to extract 46 radiomics features and estimate absorbed dose in 105 primary and metastatic liver lesions. Robust radiomics modeling was based on bootstrapped multivariate logistic regression with shrinkage regularization (LASSO) and Cox regression with LASSO. Nested cross-validation and bootstrap resampling were used for optimal parameter/feature selection and for guarding against overfitting risks. Spearman rank correlation was used to analyze feature associations. Area under the receiver-operating characteristics curve (AUC) was used for lesion response (at first follow-up) analysis while Kaplan-Meier plots and c-index were used to assess progression model performance. Models with absorbed dose only, radiomics only and combined models were developed to predict lesion outcome.Results The phantom study identified 15/46 reproducible and robust radiomics features that were subsequently used in the patient models. A lesion response model with zone percentage (ZP) and mean absorbed dose achieved an AUC of 0.729 (95%CI: 0.702-0.758) and a progression model with zone size nonuniformity (ZSN) and absorbed dose achieved a c-index of 0.803 (95% CI: 0.790-0.815) on nested cross validation (CV). The combined models outperformed the radiomics only and absorbed dose only models, but statistical significance was not achieved with this limited data set.Conclusion We have developed new lesion-level response and progression models using textural radiomics features, derived from 90Y PET combined with mean absorbed dose for predicting outcome in radioembolization. These encouraging results will need further validation in independent datasets prior to clinical adoption.

PO-1787 The Effect of Reducing CT Dose on Proton Therapy Dose Calculation – Phantom Study

2021 ◽  
Vol 161 ◽  
pp. S1512-S1513
Author(s):  
M. Elhamiasl ◽  
K. Salvo ◽  
E. Sterpin ◽  
J. Nuyts
Keyword(s):  
Proton Therapy ◽  
Dose Calculation ◽  
Phantom Study ◽  
Ct Dose

scholarly journals Quantifying daily variation in volume and dose to the prostate, rectum and bladder using cone-beam computerised tomography

2013 ◽  
Vol 13 (1) ◽  
pp. 79-86 ◽  
Author(s):  
Neil McParland ◽  
Moira Pearson ◽  
Joanna Wong ◽  
Ivana Sigur ◽  
Coral Stenger ◽  
...  
Keyword(s):  
Treatment Plan ◽  
Cone Beam Ct ◽  
Intensity Modulated Radiation Therapy ◽  
Cone Beam ◽  
Rank Test ◽  
Computerised Tomography ◽  
Dose Prediction ◽  
Ct Dose ◽  
Dose Metrics ◽  
Signed Rank Test

AbstractIntroductionIn the era of dose escalation for localised prostate cancer, the dose–volume histogram (DVH) is integral to the assessment of rectum and bladder dose constraints. However, reliance on a single planning computerised tomography-based (P-CT) dose distribution may not account for variations in delivered dose that results from deformation of the prostate, bladder and rectum. This study uses cone-beam CT (CBCT) datasets from five patients to investigate the concordance between the dose prediction from the initial treatment plan and the dose delivered during treatment.MethodsThe intensity-modulated radiation therapy distribution used for treatment was superimposed on alternate day CBCT images for each patient. Dose metrics and absolute volumes for the prostate, rectum and bladder were extracted from the CBCT-based DVH. Differences in dose and volumes were compared with the P-CT values, and significance was tested using the Wilcoxon signed-rank test.ResultsFor all five case studies, the prostate dose coverage on CBCT plans was lower than predicted with an average reduction of 3% in mean dose. Significant differences in rectal volumes and dose were observed in two out of five and four out of five patients, respectively. Reductions in bladder volume and subsequent increases in dose were observed for three out of five patients.ConclusionThe DVH from P-CT was unable to consistently predict the dose delivered to the bladder and rectum. The current bowel and bladder preparation protocols used at our institution did not eliminate variation in bladder and rectum volumes for the five patients included in this study.

scholarly journals Tumor Response Prediction in 90Y Radioembolization with PET-based Radiomics Features and Absorbed Dose Metrics

2020 ◽  
Author(s):  
Lise Wei ◽  
Can Cui ◽  
Jiarui Xu ◽  
Ravi Kaza ◽  
Issam El Naqa ◽  
...  
Keyword(s):  
Cross Validation ◽  
Cox Regression ◽  
Statistical Significance ◽  
Absorbed Dose ◽  
Phantom Study ◽  
Operating Characteristics ◽  
Data Set ◽  
Progression Model ◽  
Dose Metrics ◽  
Combined Models

Abstract Purpose To evaluate whether lesion radiomics features and absorbed dose metrics extracted from post-therapy 90Y PET can be integrated to better predict outcomes in microsphere radioembolization of liver malignancies. Methods Given the noisy nature of 90Y PET, first, a liver phantom study with repeated acquisitions and varying reconstruction parameters was used to identify a subset of robust radiomics features for the patient analysis. In 36 radioembolization procedures, 90Y PET/CT was performed within a couple of hours to extract 46 radiomics features and estimate absorbed dose in 105 primary and metastatic liver lesions. Robust radiomics modeling was based on bootstrapped multivariate logistic regression with shrinkage regularization (LASSO) and Cox regression with LASSO. Nested cross-validation and bootstrap resampling were used for optimal parameter/feature selection and for guarding against overfitting risks. Spearman rank correlation was used to analyze feature associations. Area under the receiver-operating characteristics curve (AUC) was used for lesion response (at first follow-up) analysis while Kaplan-Meier plots and c-index were used to assess progression model performance. Models with absorbed dose only, radiomics only and combined models were developed to predict lesion outcome.Results The phantom study identified 15/46 reproducible and robust radiomics features that were subsequently used in the patient models. A lesion response model with zone percentage (ZP) and mean absorbed dose achieved an AUC of 0.729 (95%CI: 0.702-0.758) and a progression model with zone size nonuniformity (ZSN) and absorbed dose achieved a c-index of 0.803 (95% CI: 0.790-0.815) on nested cross validation (CV). Although the combined models outperformed the radiomics only and absorbed dose only models, statistical significance was not achieved with the current limited data set to establish expected superiority.Conclusion We have developed new lesion-level response and progression models using textural radiomics features, derived from 90Y PET combined with mean absorbed dose for predicting outcome in radioembolization. These encouraging, but limited results, will need further validation in independent and larger datasets prior to any clinical adoption.

scholarly journals Reference phantom selection in pediatric computed tomography using data from a large, multicenter registry

2021 ◽  
Author(s):  
Philip W. Chu ◽  
Sophronia Yu ◽  
Yifei Wang ◽  
J. Anthony Seibert ◽  
Luisa F. Cervantes ◽  
...  
Keyword(s):  
Computed Tomography ◽  
San Francisco ◽  
Body Region ◽  
Dose Length Product ◽  
Actual Usage ◽  
Ct Dose ◽  
Reference Phantom ◽  
Usage Patterns ◽  
Dose Metrics ◽  
Using Data

Abstract Background Radiation dose metrics vary by the calibration reference phantom used to report doses. By convention, 16-cm diameter cylindrical polymethyl-methacyrlate phantoms are used for head imaging and 32-cm diameter phantoms are used for body imaging in adults. Actual usage patterns in children remain under-documented. Objective This study uses the University of California San Francisco International CT Dose Registry to describe phantom selection in children by patient age, body region and scanner manufacturer, and the consequent impact on radiation doses. Materials and methods For 106,837 pediatric computed tomography (CT) exams collected between Jan. 1, 2015, and Nov. 2, 2020, in children up to 17 years of age from 118 hospitals and imaging facilities, we describe reference phantom use patterns by body region, age and manufacturer, and median and 75th-percentile dose–length product (DLP) and volume CT dose index (CTDIvol) doses when using 16-cm vs. 32-cm phantoms. Results There was relatively consistent phantom selection by body region. Overall, 98.0% of brain and skull examinations referenced 16-cm phantoms, and 95.7% of chest, 94.4% of abdomen and 100% of cervical-spine examinations referenced 32-cm phantoms. Only GE deviated from this practice, reporting chest and abdomen scans using 16-cm phantoms with some frequency in children up to 10 years of age. DLP and CTDIvol values from 16-cm phantom-referenced scans were 2–3 times higher than 32-cm phantom-referenced scans. Conclusion Reference phantom selection is highly consistent, with a small but significant number of abdomen and chest scans (~5%) using 16-cm phantoms in younger children, which produces DLP values approximately twice as high as exams referenced to 32-cm phantoms

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