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Inverse Planning

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https://www.readbyqxmd.com/read/28220185/small-bowel-protection-in-imrt-for-rectal-cancer-a%C3%A2-dosimetric-study-on-supine-vs-prone-position
#1
Julia Koeck, Katharina Kromer, Frank Lohr, Tobias Baack, Kerstin Siebenlist, Sabine Mai, Sylvia Büttner, Jens Fleckenstein, Frederik Wenz
BACKGROUND: This treatment planning study analyzes dose coverage and dose to organs at risk (OAR) in intensity-modulated radiotherapy (IMRT) of rectal cancer and compares prone vs. supine positioning as well as the effect of dose optimization for the small bowel (SB) by additional dose constraints in the inverse planning process. PATIENTS AND METHODS: Based on the CT datasets of ten male patients in both prone and supine position, a total of four different IMRT plans were created for each patient...
February 20, 2017: Strahlentherapie und Onkologie: Organ der Deutschen Röntgengesellschaft ... [et Al]
https://www.readbyqxmd.com/read/28211070/use-of-proximal-operator-graph-solver-for-radiation-therapy-inverse-treatment-planning
#2
Xinmin Liu, Charles Pelizzari, Andrew H Belcher, Zachary Grelewicz, Rodney D Wiersma
PURPOSE: Most radiation therapy optimization problems can be formulated as an unconstrained problem and solved efficiently by quasi-Newton methods such as the Limited-memory Broyden-Fletcher-Goldfarb-Shanno (L-BFGS) algorithm. However, several next generation planning techniques such as total variation regularization based optimization and MV+kV optimization, involve constrained or mixed-norm optimization, and cannot be solved by quasi-Newton methods. Using standard optimization algorithms on such problems often leads to prohibitively long optimization times and large memory requirements...
February 17, 2017: Medical Physics
https://www.readbyqxmd.com/read/28185762/biochemical-control-and-toxicity-for-favorable-and-intermediate-risk-patients-using-real-time-intraoperative-inverse-optimization-prostate-seed-implant-less-is-more
#3
G Shukla, A Sarkar, A Hanlon, E Crockett, H C Chen, J Martelli-Raben, A Glick, B Benge, M Lobis, S Terranova, T Desperito, D Cozzolino, E Kemmerer, F Mourtada, A Raben
PURPOSE: To report the biochemical control rate and clinical outcomes with real-time inverse planning (inverse optimization prostate seed implant [IO-PSI]) for favorable-risk (FR) and intermediate-risk (IR) prostate adenocarcinoma in a community practice setting. This analysis is an extended followup of our initial report, with favorable early biochemical control rate (biochemical nonevidence of disease) of 97% at 4 years. METHODS AND MATERIALS: Three hundred fifty-seven evaluable patients with FR and IR prostate cancer underwent real-time IO-PSI (iodine-125/145 Gy or palladium-103/120 Gy) between 2001 and 2013...
February 6, 2017: Brachytherapy
https://www.readbyqxmd.com/read/28168333/conditional-maximum-likelihood-estimation-in-semiparametric-transformation-model-with-ltrc-data
#4
Chyong-Mei Chen, Pao-Sheng Shen
Left-truncated data often arise in epidemiology and individual follow-up studies due to a biased sampling plan since subjects with shorter survival times tend to be excluded from the sample. Moreover, the survival time of recruited subjects are often subject to right censoring. In this article, a general class of semiparametric transformation models that include proportional hazards model and proportional odds model as special cases is studied for the analysis of left-truncated and right-censored data. We propose a conditional likelihood approach and develop the conditional maximum likelihood estimators (cMLE) for the regression parameters and cumulative hazard function of these models...
February 6, 2017: Lifetime Data Analysis
https://www.readbyqxmd.com/read/28164082/semiautomated-3d-spine-reconstruction-from-biplanar-radiographic-images-prediction-of-intervertebral-loading-in-scoliotic-subjects
#5
Tito Bassani, Claudia Ottardi, Francesco Costa, Marco Brayda-Bruno, Hans-Joachim Wilke, Fabio Galbusera
The present study proposes a semiautomatic software approach to reconstruct 3D subject-specific musculoskeletal model of thoracolumbar spine from radiographic digitized images acquired with EOS system. The approach is applied to evaluate the intervertebral loads in 38 standing adolescents with mild idiopathic scoliosis. For each vertebra, a set of landmarks was manually identified on radiographic images. The landmark coordinates were processed to calculate the following vertebral geometrical properties in the 3D space (i) location (ii) dimensions; and (iii) rotations...
2017: Frontiers in Bioengineering and Biotechnology
https://www.readbyqxmd.com/read/28154532/whole-brain-magnetic-resonance-image-atlases-a-systematic-review-of-existing-atlases-and-caveats-for-use-in-population-imaging
#6
REVIEW
David Alexander Dickie, Susan D Shenkin, Devasuda Anblagan, Juyoung Lee, Manuel Blesa Cabez, David Rodriguez, James P Boardman, Adam Waldman, Dominic E Job, Joanna M Wardlaw
Brain MRI atlases may be used to characterize brain structural changes across the life course. Atlases have important applications in research, e.g., as registration and segmentation targets to underpin image analysis in population imaging studies, and potentially in future in clinical practice, e.g., as templates for identifying brain structural changes out with normal limits, and increasingly for use in surgical planning. However, there are several caveats and limitations which must be considered before successfully applying brain MRI atlases to research and clinical problems...
2017: Frontiers in Neuroinformatics
https://www.readbyqxmd.com/read/28133746/development-of-an-autonomous-treatment-planning-strategy-for-radiation-therapy-with-effective-use-of-population-based-prior-data
#7
Huan Wang, Peng Dong, Hongcheng Liu, Lei Xing
PURPOSE: Current treatment planning remains a costly and labor intensive procedure and requires multiple trial-and-error adjustments of system parameters such as the weighting factors and prescriptions. The purpose of this work is to develop an autonomous treatment planning strategy with effective use of prior knowledge and in a clinically realistic treatment planning platform to facilitate radiation therapy workflow. METHOD: Our technique consists of three major components: (i) a clinical treatment planning system (TPS); (ii) a formulation of decision-function constructed using an assemble of prior treatment plans; (iii) a plan evaluator or decision-function and an outer-loop optimization independent of the clinical TPS to assess the TPS-generated plan and to drive the search toward a solution optimizing the decision-function...
December 10, 2016: Medical Physics
https://www.readbyqxmd.com/read/28125362/duration-of-treatment-in-prostate-cancer-patients-treated-with-abiraterone-acetate-or-enzalutamide
#8
Dominic Pilon, Ajay S Behl, Lorie A Ellis, Bruno Emond, Patrick Lefebvre, Nancy A Dawson
BACKGROUND: Abiraterone acetate (AA) and enzalutamide (ENZ) are oral therapies offering survival benefit to metastatic castration-resistant prostate cancer (mCRPC) patients. Despite the availability of multiple treatment options for mCRPC, there is a lack of information on the effect that being initiated on AA or ENZ has on the combined prostate cancer treatment duration. OBJECTIVE: To compare the combined duration of prostate cancer treatments of patients initiated on AA with that of patients initiated on ENZ...
February 2017: Journal of Managed Care & Specialty Pharmacy
https://www.readbyqxmd.com/read/28118401/arbitrary-symmetric-running-gait-generation-for-an-underactuated-biped-model
#9
Behnam Dadashzadeh, Mohammad Esmaeili, Chris Macnab
This paper investigates generating symmetric trajectories for an underactuated biped during the stance phase of running. We use a point mass biped (PMB) model for gait analysis that consists of a prismatic force actuator on a massless leg. The significance of this model is its ability to generate more general and versatile running gaits than the spring-loaded inverted pendulum (SLIP) model, making it more suitable as a template for real robots. The algorithm plans the necessary leg actuator force to cause the robot center of mass to undergo arbitrary trajectories in stance with any arbitrary attack angle and velocity angle...
2017: PloS One
https://www.readbyqxmd.com/read/28115532/marginal-prescription-equivalent-to-the-isocenter-prescription-in-lung-stereotactic-body-radiotherapy-preliminary-study-for-japan-clinical-oncology-group-trial-jcog1408
#10
Daisuke Kawahara, Shuichi Ozawa, Tomoki Kimura, Akito Saito, Teiji Nishio, Takeo Nakashima, Yoshimi Ohno, Yuji Murakami, Yasushi Nagata
A new randomized Phase III trial, the Japan Clinical Oncology Group (JCOG) 1408, which compares two dose fractionations (JCOG 0403 and JCOG 0702) for medically inoperable Stage IA NSCLC or small lung lesions clinically diagnosed as primary lung cancer, involves the introduction of a prescribed dose to the D95% of the planning target volume (PTV) using a superposition/convolution algorithm. Therefore, we must determine the prescribed dose in the D95% prescribing method to begin JCOG1408. JCOG 0702 uses density correction and the D95% prescribing method...
January 2017: Journal of Radiation Research
https://www.readbyqxmd.com/read/28114107/generation-of-synthetic-ct-data-using-patient-specific-daily-mr-image-data-and-image-registration
#11
Kim Melanie Kraus, Oliver Jäkel, Nina I Niebuhr, Asja Pfaffenberger
To fully exploit the advantages of magnetic resonance imaging (MRI) for radiotherapy (RT) treatment planning, a method is required to overcome the problem of lacking electron density information. We aim to establish and evaluate a new method for computed tomography (CT) data generation based on MRI and image registration. The thereby generated CT data is used for dose accumulation. We developed a process flow based on an initial pair of rigidly co-registered CT and T2-weighted MR image representing the same anatomical situation...
February 21, 2017: Physics in Medicine and Biology
https://www.readbyqxmd.com/read/28108827/the-prognostic-impact-of-unplanned-excisions-in-a-cohort-of-728-soft-tissue-sarcoma-patients-a-multicentre-study
#12
Maria Anna Smolle, Per-Ulf Tunn, Elisabeth Goldenitsch, Florian Posch, Joanna Szkandera, Marko Bergovec, Bernadette Liegl-Atzwanger, Andreas Leithner
BACKGROUND: Unplanned excisions (UE) of soft tissue sarcomas (STS) carry a high risk for local recurrence (LR) due to marginal/intralesional resections. However, there are reports about improved prognosis for UE patients who have re-resection compared with patients who undergo planned surgery. The present multicentre study was designed to define characteristics of UE patients and to investigate the impact of UE on subsequent therapy and patient outcomes. METHODS: A total of 728 STS patients (376 males, 352 females; mean age: 58 years) who underwent definite surgery at one of three tumour centres were retrospectively included...
January 20, 2017: Annals of Surgical Oncology
https://www.readbyqxmd.com/read/28102944/a-simple-and-robust-trajectory-based-stereotactic-radiosurgery-treatment
#13
Byron Wilson, Karl Otto, Ermias Gete
INTRODUCTION: We present a Trajectory-based Volumetric Modulated Arc Therapy (TVMAT) technique for Stereotactic Radiosurgery (SRS) that takes advantage of a modern linacs ability to modulate dose rate and move the couch dynamically. In addition, we investigate the quality of the developed TVMAT method and the dosimetric accuracy of the technique. METHODS: The main feature of the TVMAT technique is a standard beam trajectory formed by dynamic motion of the treatment couch and the linac gantry...
January 2017: Medical Physics
https://www.readbyqxmd.com/read/28102309/integration-of-visual-and-joint-information-to-enable-linear-reaching-motions
#14
Henry Eberle, Slawomir J Nasuto, Yoshikatsu Hayashi
A new dynamics-driven control law was developed for a robot arm, based on the feedback control law which uses the linear transformation directly from work space to joint space. This was validated using a simulation of a two-joint planar robot arm and an optimisation algorithm was used to find the optimum matrix to generate straight trajectories of the end-effector in the work space. We found that this linear matrix can be decomposed into the rotation matrix representing the orientation of the goal direction and the joint relation matrix (MJRM) representing the joint response to errors in the Cartesian work space...
January 19, 2017: Scientific Reports
https://www.readbyqxmd.com/read/28100416/a-retrospective-analysis-of-the-clinical-effects-of-neoadjuvant-combination-therapy-with-full-dose-gemcitabine-and-radiation-therapy-in-patients-with-biliary-tract-cancer
#15
S Kobayashi, A Tomokuni, K Gotoh, H Takahashi, H Akita, S Marubashi, T Yamada, T Teshima, K Fukui, Y Fujiwara, M Sakon
PURPOSE: This study aims to evaluate survival and the objective response to neoadjuvant combination therapy with gemcitabine and radiation therapy in patients with biliary tract cancer. METHODS: The chemoradiation therapy regimen consisted of 3 cycles of full-dose gemcitabine (1000 mg/m(2) at days 1, 8, and 15, every 4 weeks) with 50-60 Gy radiation. We compared 27 patients who received neoadjuvant chemoradiation therapy and 79 patients who were treated without neoadjuvant therapy...
January 11, 2017: European Journal of Surgical Oncology
https://www.readbyqxmd.com/read/28089602/particle-swarm-optimizer-for-weighting-factor-selection-in-intensity-modulated-radiation-therapy-optimization-algorithms
#16
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 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
#17
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
#18
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
#19
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
#20
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
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