bluuebunny/crossref_metadata_2025_split huggingface dataset:
TH‐AB‐304‐05: Predicting Distant Failure in Lung SBRT Using Clinical Parameters
Authors: Zhou Z , Cannon N , Folkerts M , Iyengar P , Choy H , Timmerman R , Jiang S , Wang J 
Published: June 2015

Purpose:To predict distant failure in lung Stereotactic Body Radiation Therapy (SBRT) using clinical parameters by machine learning algorithms with a new optimal parameter selection strategy.Methods:Support Vector Machine (SVM) based method is used to construct the model to predict distant failure using 143 lung cancer patients underwent SBRT at our institute. Meanwhile, Artificial Neural Network (ANN) and Logistic Regression (LR) based methods are applied for comparisons. The clinical parameters for each patient include demographic parameters (4), tumor characteristics (6), treatment faction schemes (2) and pretreatment medicines (6). The total number of clinical parameters is 18. The model construction method consists of two steps: (1) selecting optimal parameter set by a new Clonal Selection Algorithm (CSA); and (2) constructing SVM, ANN and LR based models for predicting distant failure in lung SBRT. Selecting optimal parameter set is considered as a combinatorial optimization problem. The proposed CSA method is one of the evolutionary algorithms that can obtain global optimal solutions, overcoming the limitation of the ranking based selection method that lead to local optimization. In addition, to overcome the effect of imbalanced data in training process, a Synthetic Minority Over‐sampling Technique (SMOTE) is applied. Sensitivity, specificity and accuracy are used to evaluate the performance of the constructed models.Results:The accuracies for ANN, LR and SVM are 70.59%, 72.04%, 75.47%, respectively. The sensitivities for ANN, LR and SVM are 76%, 60.47% and 82%, while the specificities for the three models are 58.14%, 69.77% and 60.47%.Conclusion:A new CSA based parameter selection method is proposed. The SVM with the proposed CSA optimal parameter set selection strategy can achieve better performance than ANN and LR for predicting distant failure in lung SBRT patients based on clinical parameters.
TH‐AB‐304‐11: The Influence of Radiotherapy Treatment Method On Dose Distribution and Its Relation to Patient Outcome in the SCOPE 1 Oesophageal Cancer Trial Using Type B Algorithms
Authors: Carrington R , Spezi E , Gwynne S , Dutton P , Hurt C , Crosby T , Staffurth J 
Published: June 2015

By applying the Mean Distance to Conformity (MDC) index to the dose distribution of a radiotherapy plan, the conformity of the 95% isodose line to the Planning Treatment Volume (PTV) can be measured, allowing both overdosing of normal tissue and underdosing of the target volume to be measured by OverMDC and UnderMDC respectively. The aim of this study was to analyse this aspect of treatment planning, in addition to volume of PTV and the treatment delivery method (3D conformal or Intensity‐Modulated Radiotherapy), and relate to patient outcome within the context of clinical trial.The OverMDC and UnderMDC of the 95% isodose line (50Gy prescribed dose) to the PTV was calculated for 97 patients from the UK SCOPE 1 trial on definitive chemoradiotherapy in oesophageal cancer. Data preparation was performed in CERR, Kaplan‐Meier and multivariate analysis undertaken in EUCLID and further tests in Excel and SPSS. A statistically significant breakpoint in the overall survival data, independent of cetuximab, was found with OverMDC (0.44cm, p<0.05). This was not the case with UnderMDC. There was a statistically significant difference in PTV volume either side of the OverMDC breakpoint (Mann Whitney p<0.001) and in OverMDC value dependent on the treatment delivery method (mean IMRT=0.21cm, mean 3D‐CRT=0.41cm Mann Whitney p<0.001). Re‐planning the worst performing patients according to OverMDC from 3D‐CRT to VMAT resulted in a mean reduction in OverMDC of 0.28cm (0.16–0.40cm). OverMDC was not significant in multivariate analysis that included age, sex, staging, tumour type, and position.We have shown in univariate analysis that a patient's OverMDC is correlated with overall survival. OverMDC is strongly related to IMRT and to a lesser extent with PTV volume. We recommend that VMAT planning should be used for oesophageal planning when available and that attention should be paid to the conformity of the 95% to the PTV.Rhys Carrington's PhD is funded by Cancer Research Wales (Grant Number: 2445)
TH‐AB‐BRB‐03: Automated Complexity Analysis of Volumetric Modulated Arc Therapy Plans
Authors: Younge K C , Matuszak M M , Janes L A , Anderson C J R , Moran J M , Roberts D A 
Published: June 2015

Purpose:Volumetric modulated arc therapy (VMAT) plans can become excessively complex with little additional dosimetric benefit due to the degenerative nature of inverse planning. Our goal is to improve the efficiency and quality of the VMAT planning process through the use of an automated complexity metric script.Methods:A metric that quantifies the complexity of VMAT plans by evaluating individual segment modulation was developed at our institution. This metric finds the ratio of the MLC leaf side length over aperture area for each control point, and calculates an MU‐weighted average of all controls points in the plan. A plug‐in script was created to enable use of the metric within our commercial treatment planning system. The script calculates the complexity metric and then compares it to metrics from previous clinical VMAT plans, all of which have passed patient specific pre‐treatment quality assurance. To set a threshold complexity value, we used the complexity metric script to analyze 517 clinical VMAT plans created in 2013–14 that passed QA (composite analysis, 95% of points passing 4%/1mm) and 57 that failed QA. This threshold was optimized based on the resulting true and false positive rates.Results:With the clinically set threshold, the complexity metric has a true positive rate of 44% for identifying plans that failed QA with a corresponding false positive rate of 6%. The false positives correspond to highly modulated plans, which may benefit from being reoptimized even though they initially passed patient specific QA.Conclusion:Our in‐house complexity metric script has the ability to streamline the VMAT planning and treatment process by alerting the planner when overly complex plans are generated. Those plans can be reoptimized before pre‐treatment QA is performed to attempt to reduce the plan complexity and therefore improve the plan delivery accuracy.This project was supported in part by P01CA059827.
TH‐AB‐BRB‐07: A Feasibility Study for Personalized Fractionation Schedule for Lung Cancer
Authors: Kim M , Stewart R , Phillips M 
Published: June 2015

Purpose:Investigate the feasibility of using spatio‐temporal optimization, i.e., fractionation schedule optimization combined with IMRT to select the patient‐specific fractionation schedule that best maximizes the tumor biologically equivalent dose (BED).Methods and materials:The optimal fractionation schedule for a patient depends on the tumor and organ at‐risk (OAR) sensitivity to fraction size (i.e., α/β), the effective tumor doubling time, and the size and location of tumor target relative to one or more OAR. We used a novel spatio‐temporal optimization method to identify the number of fractions N that maximizes the tumor BED using 3D BED distribution for sixteen lung phantom cases. The selection of the optimal fractionation schedule used equivalent 30‐fraction OAR constraints for the heart (Dmean < 45 Gy), lungs (Dmean < 20 Gy), cord (Dmax < 45 Gy), esophagus (Dmax < 63 Gy), and unspecified tissues (D05 < 63 Gy). To asses plan quality, we considered the min, mean, max and D95 tumor BED and the equivalent uniform dose (EUD) for optimized plans to the corresponding BED values for a conventional IMRT plan (60 Gy in 30 fractions). A sensitivity analysis was performed to assess the effects on optimal fractionation schedule of the effective tumor doubling time (Td = 3–100 days) and lag‐time for accelerated repopulation (Tk = 0 to 10 days)Results:For a tumor α/β = 10Gy, tumor max, min, mean, and D95 BED were about 20% larger than the BED for the conventional prescription. The EUD for the optimized fractionation schedule was up to 17% larger than conventional prescription. For fast proliferating tumor (Td < 10 days), there was no significant increase in tumor dose but the treatment course could be shortened, offering convenience for patients and efficient allocation of resources.
TH‐AB‐BRB‐09: Effect of Hydrogel Spacer On Achievable Rectal DVH for IMRT in Prostate Cancer
Authors: Bosch W , Olsen L , Straube W , DeWees T , Mariados N , Sylvester J , Shah D , Kurtzman S , Zimberg S , Michalski J 
Published: June 2015

Purpose:Implanted tissue spacers show great promise in reducing radiation dose to organs at risk (OAR) and/or permitting dose escalation to target volumes in IMRT plans. Dosimetric benefits have been demonstrated in a randomized study of such a device despite variations in plan optimization. The purpose of this analysis was to quantify the dosimetric effect of a tissue spacer using a validated prostate DVH prediction model trained with previous high‐quality clinical prostate plans.Methods:Imaging and treatment planning for men undergoing IMRT for localized stage T1‐T2 prostate cancer was performed before and after hydrogel spacer implantation between the prostate and anterior rectum. Pre‐ and post‐implant plans were independently optimized to satisfy dose‐volume criteria for rectum, bladder, and penile bulb. Image segmentation data were used to predict DVHs achievable using IMRT for rectum and bladder with institutionally‐validated model parameters [Medical Physics 39, 7446 (2012); doi: 10.1118/1.4761864]. Predicted and actual clinical DVHs (cDVH) for rectum were used to compare pre‐ and post‐implant plans.Results:101 pairs of plans from 5 clinical sites treating at least 14 spacer subjects each were analyzed. An average ± s.d. absolute reduction of 9.4 ± 6.5 % in V60 and 7.0 ± 4.6 % in V70 was seen for pDVH. Corresponding reductions in cDVH were 10.3 ± 6.2 % and 8.0 ± 4.3, respectively. Standard deviations of corresponding pDVH and cDVH values were similar. Correlation coefficients between predicted and actual Vx values were computed for pre‐implant, post‐implant, and pre‐post Vx differences. Correlations between pDVH and cDVH were significantly positive, but not uniform among clinical sites, suggesting differences in plan optimization.Conclusion:Predicted DVHs showed an absolute difference of nearly 10% in rectal volume receiving ≥ 60 Gy (50.4% relative reduction in V60) with use of peri‐rectal spacer, consistent with analysis of clincal pre‐ and post‐implant plans.This work was supported by a research grant from Augmenix, Inc.
TH‐AB‐BRB‐10: How Many Lesions Can Be Treated with Radiosurgery? Whole Brain Dose From Radiosurgery of Multiple Targets
Authors: Becker S , Jozsef G , Presser J , Kondziolka D 
Published: June 2015

Purpose:Multiple brain metastases are a frequent indication for stereotactic radiosurgery (SRS). There is concern that as radiation doses to normal brain increase, neurocognitive toxicity increases too. In this report, we estimate how many lesions and what total volume of tumor(s) can be irradiated before a whole brain dose of 8 Gy is reached.Methods:Multiple tumor SRS was simulated in Matlab (Mathworks, Inc) using pre‐calculated dose distributions (kernels) created from single isocenter shots for 4mm, 8mm and 16mm targets, and composite shots for 24mm and 36mm targets in GammaPlan (Elekta, Inc Sweden). Tumors of varying size from 1–36mm were randomly placed throughout the brain and covered with dose until the mean normal brain dose reached 8Gy. Selection of tumor size, dose coverage, selectivity, normalization, and maximum dose were based off NYU Gamma Knife clinical metastases database. Scenarios were run both for mixed tumor sizes and a select few fixed tumors sizes.Results:The mean number of tumors treated, V12, and total tumor volume treated using mixed tumor size distribution were 40.1±8.6, 180.2±28.8cc, and 41.1±12.7cc. For the simulation runs utilizing tumor size fixed ranges of 0–4mm, 4–8mm, 8–16mm, 16–24mm, 24–36mm, the average contribution per tumor to a whole brain dose was 0.045Gy, 0.097Gy, 0.359Gy, 0.635Gy, and 1.203Gy, respectively.Conclusion:GK SRS would require an average of 6.7 24–36mm tumors, 177.3 0–4mm tumors, or 40.1 tumors of mixed sizes to be treated to reach 8 Gy whole normal brain dose for a single session. Therefore, this study alleviates the concern that radiosurgery for a large number of tumors or treating additional newly formed metastases after previous SRS can lead to high whole brain doses. The ability to safely retreat enables the physician to consider new SRS instead of whole brain radiotherapy when additional metastases appear.
TH‐AB‐BRA‐01: Biologically Based Prostate Cancer Treatment Planning with Combined Brachytherapy and External Beam Radiotherapy
Authors: Qiu X , Voros L , Cohen G , Mageras G , Yang J , Zaider M 
Published: June 2015

Purpose:Currently, when external beam radiotherapy (EBRT) is combined with brachytherapy, they are planned independently of one another. Standard EBRT strives to deliver homogeneous physical dose to target, ignoring the non‐homogeneous nature of brachytherapy. Here, we take advantage of the difference in dose distribution and the resulting biologic effects from both modalities, and examine an alternative approach to deliver homogeneous biological effect. Specifically, we implement the new methodology to the combination of permanent seed brachytherapy and IMRT for the treatment of prostate cancer.Methods:Prostate cancer treatments consisting of 125I (or 103Pd) implants (110 Gy or 100 Gy, respectively) followed by 45 Gy in 25 IMRT fractions are considered. A biological iso‐effective dose (IED) is calculated from clinically‐derived biologic parameters to determine the desired dose for each voxel within the target and dose constraints for normal tissue. Steep dose gradients are avoided by replacing the voxel doses required by IED with iso‐dosimetric optimization structures for IMRT planning. For sub‐volumes receiving large brachytherapy doses less than 45 Gy physical dose constraints are imposed; similarly, for cool sub‐volumes, more than 45 Gy physical dose constraints are imposed.Results:Retrospective evaluation of patient cases shows that improvement in therapeutic ratio is obtained with the new IED‐based treatment plan optimization. Dose distribution, IED‐volume histograms, and IED‐equivalent DVH for a 45‐fraction IMRT treatment are presented.Conclusion:We describe a new biological optimization‐based treatment planning implementation. IED is calculated (rather than physical dose) while respecting practical aspects of the EBRT plan. The resulting plans predict reduced toxicity to urethra, bladder and rectum. The results require further clinical verification in a larger number of cases. This new methodology can be generalized to any treatment combination.Funding Support: Research grant from Varian Medical Systems. Conflict of Interest: Xinjie Qiu, Gig Mageras, Marco Zaider: Varian Medical Systems; Laszlo Voros, Gilad Cohen, Jie Yang: None.
TH‐CD‐210‐01: Recent Advances in SPECT/CT and PET/CT for Oncology
Authors: Kappadath S. 
Published: June 2015

There have been significant recent advances in SPECT/CT and PET/CT for Oncology and Cardiology. In oncologic imaging, some commercial SPECT/CT systems now output quantitative uptake values; calibration and calculation of these quantitative uptake values will be discussed. Advances in PET detector design and PET data acquisition modes that have implemented in commercial PET/CT systems will be presented. Innovations in iterative reconstruction of SPECT/CT and PET/CT will also be described.In cardiac imaging, novel collimator designs, such as multi‐pinhole and locally focusing collimators arranged in geometries that are optimized for cardiac imaging have been implemented to reduce imaging time and radiation dose. These new collimators have been coupled with solid‐state photon detectors. The new SPECT scanners demonstrate up to a 7‐fold increase in photon sensitivity and up to 2 times improvement in image resolution. Although PET scanners are used primarily for oncological imaging, cardiac imaging can benefit from the improved PET sensitivity of 3D systems without inter‐plane septa and implementation of the time‐of‐flight reconstruction. Additionally, all major PET vendors now implement resolution recovery techniques. These new methods improve image contrast, image resolution, and reduce image noise for cardiac imaging. New quantification techniques have been proposed for analysis of cardiac SPECT and PET images. These include direct change analysis, motion‐frozen analysis, hybrid quantification of SPECT and anatomical CT angiography data, and integration of several quantitative parameters in composite scores.Learning Objectives:

To discuss clinical implementation of commercial quantitative SPECT/CT systems
To describe advances in PET detector design and data acquisition
To report on innovations in iterative reconstruction of SPECT/CT and PET/CT
4 Describe novel hardware designed for cardiac SPECT
Understand how recent hardware advances in PET/CT are relevant to cardiology
Describe new software techniques for quantification of cardiac SPECT and PET
TH‐E‐304‐00: Reference Dosimetry for Beam Modalities Other Than MV Photons
Authors: McEwen Malcolm 
Published: June 2015

It is fair to say that the clinical determination of absorbed dose in a high‐energy photon beam is the only situation where there is currently a direct chain of traceability from the standards laboratory to the end‐user and the protocol requires only ‘simple’ conversion/ correction factors. For all other modalities the primary standard is in a different quantity (e.g., air kerma) or in the right quantity but a different radiation beam (e.g., for proton dosimetry) from what is required for the clinical dose delivery. Complex conversion factors are often then required in applying protocols to give the desired final quantity. Such conversion factors can be from kerma to dose (in the case of kilovoltage x‐rays or brachytherapy) or from one type of radiation beam to another (in the case of electron or proton beams). Even non‐standard MV photon beams (e.g. non‐standard geometry, presence of a magnetic field) can have a significant impact on the procedure that must be followed compared to what is found in TG‐51. While national and international bodies, such as the AAPM and the IAEA, primarily address the end‐user's needs with protocols and guidelines, calibration laboratories are developing new measurement standards and approaches that should simplify the calibration chain and therefore lead to simpler, more robust procedures to yield absorbed dose in the beam of interest in the radiation therapy clinic.This session will provide a broad overview of the worldwide developments currently in progress, and also planned for the near future, of absorbed dose standards for a range of beam modalities including: Proton beamsHDR and LDR brachytherapyNon‐standard photon fields (small fields, impact of magnetic fields, etc)Learning Objectives:

Understand the present traceability chain for all beam modalities in regular use in the radiation therapy clinic.
Understand the current and planned development of absorbed dose standards for modalities other than linac photon beams.
Understand the physical basis of these standards and the potential impact on end‐user dosimetry.
Understand the likely impact of these standards developments on dosimetry protocols in the coming 5–10 years.
TH‐E‐304‐01: Overview of Primary Standards for Reference Dosimetry
Authors: McEwen M. 
Published: June 2015

It is fair to say that the clinical determination of absorbed dose in a high‐energy photon beam is the only situation where there is currently a direct chain of traceability from the standards laboratory to the end‐user and the protocol requires only ‘simple’ conversion/ correction factors. For all other modalities the primary standard is in a different quantity (e.g., air kerma) or in the right quantity but a different radiation beam (e.g., for proton dosimetry) from what is required for the clinical dose delivery. Complex conversion factors are often then required in applying protocols to give the desired final quantity. Such conversion factors can be from kerma to dose (in the case of kilovoltage x‐rays or brachytherapy) or from one type of radiation beam to another (in the case of electron or proton beams). Even non‐standard MV photon beams (e.g. non‐standard geometry, presence of a magnetic field) can have a significant impact on the procedure that must be followed compared to what is found in TG‐51. While national and international bodies, such as the AAPM and the IAEA, primarily address the end‐user's needs with protocols and guidelines, calibration laboratories are developing new measurement standards and approaches that should simplify the calibration chain and therefore lead to simpler, more robust procedures to yield absorbed dose in the beam of interest in the radiation therapy clinic.This session will provide a broad overview of the worldwide developments currently in progress, and also planned for the near future, of absorbed dose standards for a range of beam modalities including: Proton beamsHDR and LDR brachytherapyNon‐standard photon fields (small fields, impact of magnetic fields, etc)Learning Objectives:

Understand the present traceability chain for all beam modalities in regular use in the radiation therapy clinic.
Understand the current and planned development of absorbed dose standards for modalities other than linac photon beams.
Understand the physical basis of these standards and the potential impact on end‐user dosimetry.
Understand the likely impact of these standards developments on dosimetry protocols in the coming 5–10 years.
TH‐E‐304‐02: Standards for Proton and Heavy Ion Beams
Authors: Tosh R. 
Published: June 2015

It is fair to say that the clinical determination of absorbed dose in a high‐energy photon beam is the only situation where there is currently a direct chain of traceability from the standards laboratory to the end‐user and the protocol requires only ‘simple’ conversion/ correction factors. For all other modalities the primary standard is in a different quantity (e.g., air kerma) or in the right quantity but a different radiation beam (e.g., for proton dosimetry) from what is required for the clinical dose delivery. Complex conversion factors are often then required in applying protocols to give the desired final quantity. Such conversion factors can be from kerma to dose (in the case of kilovoltage x‐rays or brachytherapy) or from one type of radiation beam to another (in the case of electron or proton beams). Even non‐standard MV photon beams (e.g. non‐standard geometry, presence of a magnetic field) can have a significant impact on the procedure that must be followed compared to what is found in TG‐51. While national and international bodies, such as the AAPM and the IAEA, primarily address the end‐user's needs with protocols and guidelines, calibration laboratories are developing new measurement standards and approaches that should simplify the calibration chain and therefore lead to simpler, more robust procedures to yield absorbed dose in the beam of interest in the radiation therapy clinic.This session will provide a broad overview of the worldwide developments currently in progress, and also planned for the near future, of absorbed dose standards for a range of beam modalities including: Proton beamsHDR and LDR brachytherapyNon‐standard photon fields (small fields, impact of magnetic fields, etc)Learning Objectives:

Understand the present traceability chain for all beam modalities in regular use in the radiation therapy clinic.
Understand the current and planned development of absorbed dose standards for modalities other than linac photon beams.
Understand the physical basis of these standards and the potential impact on end‐user dosimetry.
Understand the likely impact of these standards developments on dosimetry protocols in the coming 5–10 years.