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Inverse Planning

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https://www.readbyqxmd.com/read/28089602/particle-swarm-optimizer-for-weighting-factor-selection-in-intensity-modulated-radiation-therapy-optimization-algorithms
#1
Jie Yang, Pengcheng Zhang, Liyuan Zhang, Huazhong Shu, Baosheng Li, Zhiguo Gui
In inverse treatment planning of intensity-modulated radiation therapy (IMRT), the objective function is typically the sum of the weighted sub-scores, where the weights indicate the importance of the sub-scores. To obtain a high-quality treatment plan, the planner manually adjusts the objective weights using a trial-and-error procedure until an acceptable plan is reached. In this work, a new particle swarm optimization (PSO) method which can adjust the weighting factors automatically was investigated to overcome the requirement of manual adjustment, thereby reducing the workload of the human planner and contributing to the development of a fully automated planning process...
January 12, 2017: Physica Medica: PM
https://www.readbyqxmd.com/read/28089095/characteristics-of-anatomy-and-function-of-the-left-atrial-appendage-and-their-relationships-in-patients-with-cardioembolic-stroke-a-3-dimensional-transesophageal-echocardiography-study
#2
Yuki Matsumoto, Yoshihiro Morino, Akiko Kumagai, Maiko Hozawa, Motoyuki Nakamura, Yasuo Terayama, Atsushi Tashiro
BACKGROUND: Increasing attention is being paid to the left atrial appendage (LAA) in the context of risk stratification in cardioembolic stroke (CES) and the requirement for meticulous planning of percutaneous closure device implantation. However, detailed systematic assessment of the LAA remains limited. METHODS: This study evaluated the anatomy and function of LAA using 3-dimensional transesophageal echocardiography (3D-TEE) on 194 consecutive patients older than 50 years old hospitalized exclusively for CES...
January 6, 2017: Journal of Stroke and Cerebrovascular Diseases: the Official Journal of National Stroke Association
https://www.readbyqxmd.com/read/28077128/treatment-planning-comparison-of-impt-vmat-and-4%C3%AF-radiotherapy-for-prostate-cases
#3
Angelia Tran, Jingjing Zhang, Kaley Woods, Victoria Yu, Dan Nguyen, Gary Gustafson, Lane Rosen, Ke Sheng
BACKGROUND: Intensity-modulated proton therapy (IMPT), non-coplanar 4π intensity-modulated radiation therapy (IMRT), and volumetric-modulated arc therapy (VMAT) represent the most advanced treatment methods based on heavy ion and X-rays, respectively. Here we compare their performance for prostate cancer treatment. METHODS: Ten prostate patients were planned using IMPT with robustness optimization, VMAT, and 4π to an initial dose of 54 Gy to a clinical target volume (CTV) that encompassed the prostate and seminal vesicles, then a boost prescription dose of 25...
January 11, 2017: Radiation Oncology
https://www.readbyqxmd.com/read/28069303/attributable-risk-of-ambient-pm10-on-daily-mortality-and-years-of-life-lost-in-chengdu-china
#4
Fei Chen, Zibing Deng, Ying Deng, Zhijiao Qiao, Lan Lan, Qiong Meng, Bin Luo, Wei Zhang, Kui Ji, Xue Qiao, Zhiwei Fan, Meixia Zhang, Yan Cui, Xing Zhao, Xiaosong Li
Attributable risk is an important indicator for planning and evaluating public health interventions. However, most current measures of the attributable risk of air pollutants have not considered temporal relationships between exposure and risk. More importantly, limited information is available regarding the attributable risk due to ambient air pollutants in basin regions like the Sichuan Basin, China. To quantify the association between PM10 and deaths in the Basin region, we used a measure proposed recently within the framework of the distributed lag non-linear model to estimate the attributable risk in Chengdu, China...
January 6, 2017: Science of the Total Environment
https://www.readbyqxmd.com/read/28057351/preparatory-co-activation-of-the-ankle-muscles-may-prevent-ankle-inversion-injuries
#5
Matthew S DeMers, Jennifer L Hicks, Scott L Delp
Ankle inversion sprains are the most frequent acute musculoskeletal injuries occurring in physical activity. Interventions that retrain muscle coordination have helped rehabilitate injured ankles, but it is unclear which muscle coordination strategies, if any, can prevent ankle sprains. The purpose of this study was to determine whether coordinated activity of the ankle muscles could prevent excessive ankle inversion during a simulated landing on a 30° incline. We used a set of musculoskeletal simulations to evaluate the efficacy of two strategies for coordinating the ankle evertor and invertor muscles during simulated landing scenarios: planned co-activation and stretch reflex activation with physiologic latency (60-ms delay)...
December 7, 2016: Journal of Biomechanics
https://www.readbyqxmd.com/read/28048925/su-f-t-15-evaluation-of-192ir-60co-and-169yb-sources-for-high-dose-rate-prostate-brachytherapy-inverse-planning-using-an-interior-point-constraint-generation-algorithm
#6
E Mok Tsze Chung, H Safigholi, A Nicolae, M Davidson, A Ravi, D Aleman, W Song
PURPOSE: The effectiveness of using a combination of three sources, (60) Co, (192) Ir and (169) Yb, is analyzed. Different combinations are compared against a single (192) Ir source on prostate cancer cases. A novel inverse planning interior point algorithm is developed in-house to generate the treatment plans. METHODS: Thirteen prostate cancer patients are separated into two groups: Group A includes eight patients with the prostate as target volume, while group B consists of four patients with a boost nodule inside the prostate that is assigned 150% of the prescription dose...
June 2016: Medical Physics
https://www.readbyqxmd.com/read/28048882/su-f-p-25-dosimetric-changes-of-brainstem-caused-by-weight-loss-during-intensity-modulated-radiation-therapy-for-nasopharyngeal-carcinoma
#7
W Hu, C Yu, Y Cai, X Zhou, W Wang, H Yang
PURPOSE: To explore dosimetric effects of brainstem (BS) caused by weight loss during the course of intensity-modulated radiation therapy (IMRT) for nasopharyngeal carcinoma (NPC). METHODS: Seventy-seven patients who were diagnosed with NPC by pathology biopsy have been enrolled. Every patients should receive weight measurement weekly and three times of computed tomography (CT) scans and replanning, at the 15th and 25th fraction during the treatment, respectively...
June 2016: Medical Physics
https://www.readbyqxmd.com/read/28048860/su-f-p-54-guidelines-to-check-image-registration-qa-of-a-clinical-deformation-registration-software-a-single-institution-preliminary-study
#8
G Gill, S Souri, A Rea, Y Chen, J Antone, X Qian, A Riegel, P Taylor, M Marrero, F Diaz, Y Cao, A Jamshidi, S Barley, V Sorell, G Karangelis, T Button, E Klein
PURPOSE: The objective of this study is to verify and analyze the accuracy of a clinical deformable image registration (DIR) software. METHODS: To test clinical DIR software qualitatively and quantitatively, we focused on lung radiotherapy and analyzed a single (Lung) patient CT scan. Artificial anatomical changes were applied to account for daily variations during the course of treatment including the planning target volume (PTV) and organs at risk (OAR). The primary CT (pCT) and the structure set (pST) was deformed with commercial tool (ImSimQA-Oncology Systems Limited) and after artificial deformation (dCT and dST) sent to another commercial tool (VelocityAI-Varian Medical Systems)...
June 2016: Medical Physics
https://www.readbyqxmd.com/read/28048805/su-f-r-42-association-of-radiomic-and-metabolic-tumor-volumes-in-radiation-treatment-of-glioblastoma-multiforme
#9
C Lopez, N Nagornaya, N Parra, D Kwon, F Ishkanian, A Markoe, A Maudsley, R Stoyanova
PURPOSE: High-throughput extraction of imaging and metabolomic quantitative features from MRI and MR Spectroscopy Imaging (MRSI) of Glioblastoma Multiforme (GBM) results in tens of variables per patient. In radiotherapy (RT) of GBM, the relevant metabolic tumor volumes (MTVs) are related to aberrant levels of N-acetyl Aspartate (NAA) and Choline (Cho). Corresponding Clinical Target Volumes (CTVs) for RT planning are based on Contrast Enhancing T1-weighted MRI (CE-T1w) and T2-weighted/Fluid Attenuated Inversion Recovery (FLAIR) MRI...
June 2016: Medical Physics
https://www.readbyqxmd.com/read/28048798/su-f-j-88-comparison-of-two-deformable-image-registration-algorithms-for-ct-to-ct-contour-propagation
#10
A Gopal, H Xu, S Chen
PURPOSE: To compare the contour propagation accuracy of two deformable image registration (DIR) algorithms in the Raystation treatment planning system - the "Hybrid" algorithm based on image intensities and anatomical information; and the "Biomechanical" algorithm based on linear anatomical elasticity and finite element modeling. METHODS: Both DIR algorithms were used for CT-to-CT deformation for 20 lung radiation therapy patients that underwent treatment plan revisions...
June 2016: Medical Physics
https://www.readbyqxmd.com/read/28048742/su-f-t-192-study-of-robustness-analysis-method-of-multiple-field-optimized-impt-plans-for-head-neck-patients
#11
Y Li, X Wang, H Li, J Wang, X Zhu, Y Li, S Frank, X Zhang
PURPOSE: Proton therapy is more sensitive to uncertainties than photon treatments due to protons' finite range depending on the tissue density. Worst case scenario (WCS) method originally proposed by Lomax has been adopted in our institute for robustness analysis of IMPT plans. This work demonstrates that WCS method is sufficient enough to take into account of the uncertainties which could be encountered during daily clinical treatment. METHODS: A fast and approximate dose calculation method is developed to calculate the dose for the IMPT plan under different setup and range uncertainties...
June 2016: Medical Physics
https://www.readbyqxmd.com/read/28048724/su-f-j-84-comparison-of-quantitative-deformable-image-registration-evaluation-tools-application-to-prostate-igart
#12
N Dogan, E Weiss, W Sleeman, G Christensen, J Williamson, J Ford
PURPOSE: Errors in displacement vector fields (DVFs) generated by Deformable Image Registration (DIR) algorithms can give rise to significant uncertainties in contour propagation and dose accumulation in Image-Guided Adaptive Radiotherapy (IGART). The purpose of this work is to assess the accuracy of two DIR algorithms using a variety of quality metrics for prostate IGART. METHODS: Pelvic CT images were selected from an anonymized database of nineteen prostate patients who underwent 8-12 serial scans during radiotherapy...
June 2016: Medical Physics
https://www.readbyqxmd.com/read/28048691/tu-ab-brc-11-moving-a-gpu-opencl-based-monte-carlo-mc-dose-engine-towards-routine-clinical-use-automatic-beam-commissioning-and-efficient-source-sampling
#13
Z Tian, Y Li, M Folkerts, S Jiang, X Jia
PURPOSE: We have previously developed a GPU-OpenCL-based MC dose engine named goMC with built-in analytical linac beam model. To move goMC towards routine clinical use, we have developed an automatic beam-commissioning method, and an efficient source sampling strategy to facilitate dose calculations for real treatment plans. METHODS: Our commissioning method is to automatically adjust the relative weights among the sub-sources, through an optimization process minimizing the discrepancies between calculated dose and measurements...
June 2016: Medical Physics
https://www.readbyqxmd.com/read/28048667/su-f-t-65-automatictreatment-planning-for-high-dose-rate-hdr-brachytherapy-with-a-vaginalcylinder-applicator
#14
Y Zhou, J Tan, S Jiang, K Albuquerque, X Jia
PURPOSE: High dose rate (HDR) brachytherapy treatment planning is conventionally performed in a manual fashion. Yet it is highly desirable to perform computerized automated planning to improve treatment planning efficiency, eliminate human errors, and reduce plan quality variation. The goal of this research is to develop an automatic treatment planning tool for HDR brachytherapy with a cylinder applicator for vaginal cancer. METHODS: After inserting the cylinder applicator into the patient, a CT scan was acquired and was loaded to an in-house developed treatment planning software...
June 2016: Medical Physics
https://www.readbyqxmd.com/read/28048639/tu-h-209-02-quality-assurance-and-qmp-for-brachytherapy-treatment-delivery-and-treatment-planning-system
#15
M Chilukuri
Learnings Objectives: 1. Although brachytherapy is the oldest form of radiation therapy, the rapid advancement of the methods of dose calculation, treatment planning and treatment delivery pushes us to keep updating our knowledge and experience to new procedures all the time. Our purpose is to present the newest applicators used in Accelerated Partial Breast Irradiation (APBI) and the techniques of using them for a maximum effective treatment. Our objective will be to get the user familiar with the Savi, Contura and ML Mammosite from the detailed description and measurements to cavity eval and choice or size, to acceptance tests and use of each...
June 2016: Medical Physics
https://www.readbyqxmd.com/read/28048617/su-f-t-342-dosimetric-constraint-prediction-guided-automatic-mulit-objective-optimization-for-intensity-modulated-radiotherapy
#16
T Song, Y Li, L Zhou
PURPOSE: For intensity modulated radiotherapy, the plan optimization is time consuming with difficulties of selecting objectives and constraints, and their relative weights. A fast and automatic multi-objective optimization algorithm with abilities to predict optimal constraints and manager their trade-offs can help to solve this problem. Our purpose is to develop such a framework and algorithm for a general inverse planning. METHODS: There are three main components contained in this proposed multi-objective optimization framework: prediction of initial dosimetric constraints, further adjustment of constraints and plan optimization...
June 2016: Medical Physics
https://www.readbyqxmd.com/read/28048562/su-f-t-378-evaluation-of-dose-volume-variability-and-parameters-between-prostate-imrt-and-vmat-plans
#17
J Chow, R Jiang, A Kiciak
PURPOSE: This study compared the rectal dose-volume consistency, equivalent uniform dose (EUD) and normal tissue complication probability (NTCP) in prostate intensity modulated radiotherapy (IMRT) and volumetric modulated arc therapy (VMAT). METHODS: For forty prostate IMRT and fifty VMAT patients treated using the same dose prescription (78 Gy/39 fraction) and dose-volume criteria in inverse planning optimization, the rectal EUD and NTCP were calculated for each patient...
June 2016: Medical Physics
https://www.readbyqxmd.com/read/28048455/we-ab-209-02-a-new-inverse-planning-framework-with-principle-based-modeling-of-inter-structural-dosimetric-tradeoffs
#18
H Liu, P Dong, L Xing
PURPOSE: Traditional radiotherapy inverse planning relies on the weighting factors to phenomenologically balance the conflicting criteria for different structures. The resulting manual trial-and-error determination of the weights has long been recognized as the most time-consuming part of treatment planning. The purpose of this work is to develop an inverse planning framework that parameterizes the inter-structural dosimetric tradeoff among with physically more meaningful quantities to simplify the search for a clinically sensible plan...
June 2016: Medical Physics
https://www.readbyqxmd.com/read/28048409/su-d-202-05-evaluation-of-four-dimensional-dose-reconstruction-under-breathing-irregularity
#19
J Yoon, I Yeo, J Jung, B Yi
PURPOSE: A method of four dimensional dose reconstruction (4D-DR) using a cine mode of an EPID to determine the delivered 4D dose distribution has been suggested. This method, however, has not been tested under irregular breathing. This study investigated their effects on 4D-DR. METHODS: The 4D-DR attempts to find the patient's breathing phase associated with each EPID image by comparing it to pre-generated-EPID-quality DRRs of every breathing phases. A lung phantom with a tumor object (3cm diameter cylinder) on a moving platform was used for this test under conditions of amplitude reduction by 1/2 during (1) the entire delivery and (2) the duration when MLC blocked the tumor (hindering the phase determination)...
June 2016: Medical Physics
https://www.readbyqxmd.com/read/28048199/su-g-brc-15-the-potential-clinical-significance-of-dose-mapping-error-for-intra-fraction-dose-mapping-for-lung-cancer-patients
#20
N Sayah, E Weiss, W Watkins, J Siebers
PURPOSE: To evaluate the dose-mapping error (DME) inherent to conventional dose-mapping algorithms as a function of dose-matrix resolution. METHODS: As DME has been reported to be greatest where dose-gradients overlap tissue-density gradients, non-clinical 66 Gy IMRT plans were generated for 11 lung patients with the target edge defined as the maximum 3D density gradient on the 0% (end of inhale) breathing phase. Post-optimization, Beams were copied to 9 breathing phases...
June 2016: Medical Physics
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