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Dose calculation algorithms

Yongxia Zhao, Yize Xu, Yunfeng Bao, Xue Geng, Tianle Zhang, Dongxue Li
OBJECTIVE: To assess the difference in absorbed organ dose and image quality for head-neck CT angiography using organ dose modulation compared with 3D smart mA modulation in different body mass indices (BMIs) using an adaptive statistical iterative reconstruction (ASiR-V) algorithm. METHODS: Three hundred patients underwent head-neck CTA were equally divided into three groups: A (18.5 kg/m2≦BMI <  24.9 kg/m2), B (24.9 kg/m2≦BMI <  29.9 kg/m2) and C (29...
November 29, 2018: Journal of X-ray Science and Technology
Syu-Jyun Peng, Cheng-Chia Lee, Hsiu-Mei Wu, Chung-Jung Lin, Cheng-Ying Shiau, Wan-Yuo Guo, David Hung-Chi Pan, Kang-Du Liu, Wen-Yuh Chung, Huai-Che Yang
BACKGROUND: Gamma knife radiosurgery (GKRS) is a common treatment for cerebral arterio-venous malformations (AVMs), particularly in cases where the malformation is deep-seated, large, or in eloquent areas of the brain. Unfortunately, these procedures can result in radiation injury to brain parenchyma. The fact that every AVM is unique in its vascular morphology makes it nearly impossible to exclude brain parenchyma from isodose radiation exposure during the formulation of a GKRS plan...
November 19, 2018: NeuroImage: Clinical
Gopa Ghosh, Gaurav Gupta, Anupam Malviya, Dinesh Saroj
Background: About 74% of head and neck cancer (HNC) patients need to undergo either definitive or postoperative radiation therapy because of aggressive nature of disease. The transition from two-dimensional conventional radiotherapy to three-dimensional conformal radiotherapy (3D-CRT) and further technological evolutions led to the successful clinical implementation of intensity modulated radiation therapy (IMRT), which constitutes an evolution of 3D-CRT. The IMRT technique gives the ability to create treatment fields with varying beam intensity using inverse planning and optimization algorithms to treat irregularly shaped target volumes with high precision...
October 2018: Journal of Cancer Research and Therapeutics
Bing-Yu Sun, Yoshihiko Hayakawa
OBJECTIVES: To examine the effect of incomplete, or total elimination of, projection data on computed tomography (CT) images subjected to statistical reconstruction and/or compressed sensing algorithms. METHODS: Multidetector row CT images were used. The algebraic reconstruction technique (ART) and the maximum likelihood-expectation maximization (ML-EM) method were compared with filtered back-projection (FBP). Effects on reconstructed images were studied when the projection data of 360° (360 projections) were decreased to 180 or 90 projections by reducing the collection angle or thinning the image data...
September 2018: Oral Radiology
Xia Huang, Jian Wang, Fan Tang, Tao Zhong, Yu Zhang
BACKGROUND: Cervical cancer is the fifth most common cancer among women, which is the third leading cause of cancer death in women worldwide. Brachytherapy is the most effective treatment for cervical cancer. For brachytherapy, computed tomography (CT) imaging is necessary since it conveys tissue density information which can be used for dose planning. However, the metal artifacts caused by brachytherapy applicators remain a challenge for the automatic processing of image data for image-guided procedures or accurate dose calculations...
November 27, 2018: Biomedical Engineering Online
Ezra Fishman, John Barron, Jade Dinh, W Schuyler Jones, Amanda Marshall, Rebecca Merkh, Holly Robertson, Kevin Haynes
Objective: Validate an algorithm that uses administrative claims data to identify eligible study subjects for the ADAPTABLE (Aspirin Dosing: A Patient-centric Trial Assessing Benefits and Long-Term Effectiveness) pragmatic clinical trial (PCT). Materials and methods: This study used medical records from a random sample of patients identified as eligible for the ADAPTABLE trial. The inclusion criteria for ADAPTABLE were a history of acute myocardial infarction (AMI) or percutaneous coronary intervention (PCI) or coronary artery bypass grafting (CABG), or other coronary artery disease (CAD), plus at least one of several risk-enrichment factors...
December 2018: Contemporary Clinical Trials Communications
Mark Kh Chan, Venus Wy Lee, Noriyuki Kadoya, Chi-Leung Chiang, Matthew Yp Wong, Ronnie Wk Leung, Steven Cheung, Oliver Blanck
Purpose: To provide a pilot dosimetric study of computed tomography (CT)-guided high-dose-rate (HDR) brachytherapy (BRT) and stereotactic body radiotherapy (SBRT) for primary and metastatic lung lesions. Material and methods: For nine lung primary and metastasis patients, 3D image-based BRT plan using a single virtual catheter was planned for 34 Gy in single fraction to the gross tumor volume (GTV) + 3 mm margin to account for tumor deformation. These plans were compared to margin-based (MB-) and robustness optimized (RO-) SBRT, assuming the same tumor deformation under real-time tumor tracking...
October 2018: Journal of Contemporary Brachytherapy
Eeva Boman, Jarkko Ojala, Maija Rossi, Mika Kapanen
OBJECTIVES: To investigate the dosimetric effect of air gaps under bolus on skin dose for left-sided post-mastectomy radiotherapy with loco regional involvement. METHODS: Eight patients were planned retrospectively with volume modulated arc therapy (VMAT) and conventional static Field-in-Field (FinF) methods. Three different setups were applied for the 5-mm bolus over the chest wall having 0, 5 or 10 mm air gap under the bolus. The dose calculation was performed using Monte Carlo (MC) simulation...
November 2018: Physica Medica: PM
Sarah-Charlotta Heidorn, Warren Kilby, Christoph Fürweger
PURPOSE: At introduction in 2014, dose calculation for the first MLC on a robotic SRS/SBRT platform was limited to a correction-based Finite-Size Pencil Beam (FSPB) algorithm. We report on the dosimetric accuracy of a novel Monte Carlo (MC) dose calculation algorithm for this MLC, included in the Precision™ treatment planning system. METHODS: A phantom was built of one slab (5.0 cm) of lung-equivalent material (0.09…0.29 g/cc) enclosed by 3.5 cm (above) and 5 cm (below) slabs of solid water (1...
November 2018: Physica Medica: PM
Hui Zhang, Zhongying Dai, Xinguo Liu, Weiqiang Chen, Yuanyuan Ma, Pengbo He, Tianyuan Dai, Guosheng Shen, Ping Yuan, Qiang Li
An accurate kernel model is of vital importance for pencil-beam dose algorithm in charged particle therapy using precise spot-scanning beam delivery, in which an accurate depiction of the low dose envelope is especially crucial. Based on the Monte Carlo method, we investigated the dose contribution of secondary particles to the total dose and proposed a novel beam model to depict the lateral dose distribution of carbon-ion pencil beam in water. We demonstrated that the low dose envelope in single-spot profiles in water could be adequately modelled with the addition of a logistic distribution to a double Gaussian one, which was verified in both single carbon-ion pencil beam and superposed fields of different sizes with multiple pencil beams...
November 2018: Physica Medica: PM
Carles Muñoz-Montplet, Jordi Marruecos, Maria Buxó, Diego Jurado-Bruggeman, Ingrid Romera-Martínez, Marta Bueno, Joan C Vilanova
PURPOSE: To assess the dosimetric impact of switching from the Analytical Anisotropic Algorithm (AAA) to Acuros XB (AXB) for both dose-to-medium (Dm) and dose-to-water (Dw) in VMAT for H&N patients. To study whether it should be linked to a change in the dose prescriptions to the PTVs and in the constraints to the OARs. METHODS: 110H&N patients treated with VMAT were included. Calculations were performed with AAA and AXB. PTV54, PTV60, PTV70, spinal cord, brainstem, brain, larynx, oral cavity, cochleas, parotid glands and mandible were delineated...
November 2018: Physica Medica: PM
Yang Lei, Xiangyang Tang, Kristin Higgins, Jolinta Lin, Jiwoong Jeong, Tian Liu, Anees Dhabaan, Tonghe Wang, Xue Dong, Robert Press, Walter J Curran, Xiaofeng Yang
PURPOSE: Quantitative Cone Beam CT (CBCT) imaging is increasing in demand for precise image-guided radiotherapy because it provides a foundation for advanced image-guided techniques, including accurate treatment setup, online tumor delineation and patient dose calculation. However, CBCT is currently limited to patient setup only in the clinic because of the severe issues in its image quality. In this study, we develop a learning-based approach to improve CBCT's image quality for extended clinical applications...
November 24, 2018: Medical Physics
L Lafitte, C Zachiu, L G W Kerkmeijer, M Ries, B Denis de Senneville
For the successful completion of medical interventional procedures, several concepts, such as daily positioning compensation, dose accumulation or delineation propagation, rely on establishing a spatial coherence between planning images and images acquired at different time instants over the course of the therapy. To meet this need, image-based motion estimation and compensation relies on fast, automatic, accurate and precise registration algorithms. However, image registration quickly becomes a challenging and computationally intensive task, especially when multiple imaging modalities are involved...
November 23, 2018: Physics in Medicine and Biology
Nasir Idkaidek, Ahmad Al-Ghazawi
Pharmacokinetics of paracetamol (APAP) was studied on-board during an air flight and compared to those on ground after 500 mg oral dose in 20 healthy human volunteer in parallel design study. Saliva samples were obtained every 15 min up to 2 h after dosing. Pharmacokinetic parameters were calculated by non compartmental analysis and one compartment models using Winnonlin program V5.2. Results have showed that on-board to ground ratios for area under curves AUC0→1 , AUC0→2 , time to reach maximum saliva concentration Tmax , absorption rate constant Ka and maximum saliva concentration Cmax were 0...
November 21, 2018: Drug Research
Leif Bungum, Julia Tagevi, Ligita Jokubkiene, Mona Bungum, Aleksander Giwercman, Nick Macklon, Claus Yding Andersen, Tobias Wirenfeldt Klausen, Niels Tørring, Ajay Kumar, Sven Olaf Skouby
This study examined longitudinal, age-related and intra-individual variation in Anti-Müllerian Hormone (AMH) in regular menstruating women and correlated the hormonal levels to the antral follicle count (AFC). The impact of variations on an algorithm for calculation of follitropin-dose for ovarian stimulation were also tested. The study was carried out at a fertility clinic of a tertiary university hospital and had a prospective trial design. Twenty-six healthy women not receiving infertility treatment aged 22 to 50 years participated...
2018: Frontiers in Endocrinology
Joey P Cheung, Erin Shugard, Nilesh Mistry, Jean Pouliot, Josephine Chen
PURPOSE: Wide bore CT scanners use extended field-of-view (FOV) reconstruction algorithms to attempt to recreate tissue truncated due to large patient habitus. Radiation therapy planning systems rely on accurate CT numbers in order to correctly plan and calculate radiation dose. This study looks at the impact of extended FOV reconstructions on CT numbers and radiation dose calculations in real patient geometries. METHODS: A large modular phantom based on real patient geometries was created to surround a CIRS Model 062M phantom...
November 20, 2018: Medical Physics
Takanori Matsuoka, Fujio Araki, Takeshi Ohno, Junichi Sakata, Hirofumi Tominaga
The purpose of this study was to investigate the dependence of volume dose indices on dose calculation algorithms for volumetric modulated arc therapy (VMAT) for stereotactic body radiotherapy (SBRT) plans to treat peripheral lung tumors by comparing them with those of Monte Carlo (MC) calculations. VMAT-SBRT plans for peripheral lung tumors were created using the Eclipse treatment planning system (TPS) for 24 patients with nonsmall cell lung cancer. VMAT dose distributions for gross tumor volume (GTV), internal target volume (ITV), and planning target volume (PTV) were calculated using the analytical anisotropic algorithm (AAA), the Acuros XB (AXB) algorithm, and a MC algorithm...
November 16, 2018: Medical Dosimetry: Official Journal of the American Association of Medical Dosimetrists
K Niepel, F Kamp, C Kurz, D Hansen, S Rit, S Neppl, J Hofmaier, D Bondesson, C Thieke, J Dinkel, C Belka, K Parodi, G Landry
Inter-fractional variations of breathing pattern and patient anatomy introduce dose uncertainties in proton therapy. One approach to monitor these variations is to utilize the cone-beam computed tomography (CT, CBCT) scans routinely taken for patient positioning, reconstruct them as 4DCBCTs, and generate 'virtual CTs' (vCTs), combining the accurate CT numbers of the diagnostic 4DCT and the geometry of the daily 4DCBCT by using deformable image registration (DIR). In this study different algorithms for 4DCBCT reconstruction and DIR were evaluated...
November 14, 2018: Zeitschrift Für Medizinische Physik
S Morato, B Juste, S Peris, R Miro, G Verdu, F Ballester, J Vijande
Radiation Therapy Planning Systems (RTPS) currently used in hospitals contain algorithms based on deterministic simplifications that do not properly consider electrons lateral transport in the areas where there are changes of density, and as a result, erroneous dose predictions could be produced. According to this, the present work proposes the use of Monte Carlo method in brachytherapy planning systems, which could affect positively on the radiotherapy treatment planning, since it provides results that are more accurate and takes into account the in homogeneities density variations...
July 2018: Conference Proceedings: Annual International Conference of the IEEE Engineering in Medicine and Biology Society
Kyeong-Hyeon Kim, Jin-Beom Chung, Tae Suk Suh, Sang-Won Kang, Seong-Hee Kang, Keun-Yong Eom, Changhoon Song, In-Ah Kim, Jae-Sung Kim
To investigate feasible treatment planning parameters, we aimed to evaluate the dosimetric and radiobiological impact of the dose calculation algorithm and grid size in the volumetric modulated arc therapy (VMAT) plan for prostate cancer. Twenty patients were selected, and the treatment plans were initially generated with anisotropic analytical algorithm (AAA) and recalculated with Acuros XB (AXB) algorithm. Various dose grids were used for AXB (1, 2, and 3 mm) and AAA (1, 3, and 5 mm) plan. Dosimetric parameters such as homogeneity index (HI) and conformity index (CI), and radiobiological parameters such as tumor control probability (TCP) and normal tissue complication probability (NTCP) were calculated...
2018: PloS One
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