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https://www.readbyqxmd.com/read/30536528/epid-based-in-vivo-dosimetry-using-dosimetry-check%C3%A2-overview-and-clinical-experience-in-a-5-yr-study-including-breast-lung-prostate-and-head-and-neck-cancer-patients
#1
William H Nailon, Daniel Welsh, Kim McDonald, Donna Burns, Julie Forsyth, Gillian Cooke, Francisco Cutanda, Linda J Carruthers, Duncan B McLaren, Josep Puxeu Vaqué, Terence Kehoe, Sankar Andiappa
BACKGROUND: Independent verification of the dose delivered by complex radiotherapy can be performed by electronic portal imaging device (EPID) dosimetry. This paper presents 5-yr EPID in vivo dosimetry (IVD) data obtained using the Dosimetry Check (DC) software on a large cohort including breast, lung, prostate, and head and neck (H&N) cancer patients. MATERIAL AND METHODS: The difference between in vivo dose measurements obtained by DC and point doses calculated by the Eclipse treatment planning system was obtained on 3795 radiotherapy patients treated with volumetric modulated arc therapy (VMAT) (n = 842) and three-dimensional conformal radiotherapy (3DCRT) (n = 2953) at 6, 10, and 15 MV...
December 7, 2018: Journal of Applied Clinical Medical Physics
https://www.readbyqxmd.com/read/30532658/dosimetric-and-monte-carlo-verification-of-jaws-only-imrt-plans-calculated-by-the-collapsed-cone-convolution-algorithm-for-head-and-neck-cancers
#2
Duong Thanh Tai, Luong Thi Oanh, Nguyen Dong Son, Truong Thi Hong Loan, James C L Chow
Aim: The aim of this study is to verify the Prowess Panther jaws-only intensity modulated radiation therapy (JO-IMRT) treatment planning (TP) by comparing the TP dose distributions for head-and-neck (H&N) cancer with the ones simulated by Monte Carlo (MC). Background: To date, dose distributions planned using JO-IMRT for H&N patients were found superior to the corresponding three-dimensional conformal radiotherapy (3D-CRT) plans. Dosimetry of the JO-IMRT plans were also experimentally verified using an ionization chamber, MapCHECK 2, and Octavius 4D and good agreements were shown...
January 2019: Reports of Practical Oncology and Radiotherapy
https://www.readbyqxmd.com/read/30527087/estimation-of-electron-density-effective-atomic-number-and-stopping-power-ratio-using-dual-layer-computed-tomography-for-radiotherapy-treatment-planning
#3
Shingo Ohira, Hayate Washio, Masashi Yagi, Tsukasa Karino, Kenji Nakamura, Yoshihiro Ueda, Masayoshi Miyazaki, Masahiko Koizumi, Teruki Teshima
PURPOSE: Assess the accuracy for quantitative measurements of electron density relative to water (ρe /ρe,w ), effective atomic number (Zeff ) and stopping power ratio relative to water (SPRw ) using a dual-layer computed tomography (DLCT) system. METHODS AND MATERIALS: A tissue characterization phantom was scanned using DLCT with varying scanning parameters (i.e., tube voltage, rotation time, CTDIvol , and scanning mode) and different reference materials. Then, electron density ρe /ρe,w and atomic number Zeff images were reconstructed, and their values were determined for each reference materials...
December 2018: Physica Medica: PM
https://www.readbyqxmd.com/read/30523998/comparing-unet-training-with-three-different-datasets-to-correct-cbct-images-for-prostate-radiotherapy-dose-calculations
#4
Guillaume Landry, David Hansen, Florian Kamp, Minglun Li, Ben Hoyle, Jochen Weller, Katia Parodi, Claus Belka, Christopher Kurz
Image intensity correction is crucial to enable cone beam computed tomography (CBCT) based radiotherapy dose calculations. This study evaluated three different deep learning based correction methods using a U-shaped convolutional neural network architecture (Unet) in terms of their photon and proton dose calculation accuracy.
 
 CT and CBCT imaging data of 42 prostate cancer patients were included. For target ground truth data generation, a CBCT correction method based on CT to CBCT deformable image registration (DIR) was used...
November 28, 2018: Physics in Medicine and Biology
https://www.readbyqxmd.com/read/30523967/deep-learning-based-surface-region-selection-for-deep-inspiration-breath-hold-dibh-monitoring-in-left-breast-cancer-radiotherapy
#5
Haibin Chen, Mingli Chen, Weiguo Lu, Bo Zhao, Steve B Jiang, Linghong Zhou, Nathan Kim, Ann Spangler, Asal Rahimi, Xin Zhen, Xuejun Gu
Deep inspiration breath hold (DIBH) with surface supervising is a common technique for cardiac dose reduction in left breast cancer radiotherapy. Surface supervision accuracy relies on the characteristics of surface region. In this study, a convolutional neural network (CNN) based automatic region-of-interest (ROI) selection method was proposed to select an optimal surface ROI for DIBH surface monitoring. The curvature entropy and the normal of each vertex on the breast cancer patient surface were calculated and formed as representative maps for ROI selection learning...
November 14, 2018: Physics in Medicine and Biology
https://www.readbyqxmd.com/read/30505721/assessment-of-positional-reproducibility-in-the-head-and-neck-on-a-1-5-t-mr-simulator-for-an-offline-mr-guided-radiotherapy-solution
#6
Yihang Zhou, Jing Yuan, Oi Lei Wong, Winky Wing Ki Fung, Ka Fai Cheng, Kin Yin Cheung, Siu Ki Yu
Background: Recently, a shuttle-based offline magnetic resonance-guided radiotherapy (MRgRT) approach was proposed. This study aims to evaluate the positional reproducibility in the immobilized head and neck using a 1.5-T MR-simulator (MR-sim) on healthy volunteers. Methods: A total of 159 scans of 14 healthy volunteers were conducted on a 1.5-T MR-sim with thermoplastic mask immobilization. MR images with isotropic 1.053 mm3 voxel size were rigidly registered to the first scan based on fiducial, anatomical and gross positions...
October 2018: Quantitative Imaging in Medicine and Surgery
https://www.readbyqxmd.com/read/30500286/murine-vs-human-tissue-compositions-implications-of-using-human-tissue-compositions-for-photon-energy-absorption-in-mice
#7
Lotte Ejr Schyns, Daniëlle Bp Eekers, Brent van der Heyden, Isabel P Almeida, Ana Vaniqui, Frank Verhaegen
METHODS: Dual energy CT (DECT) images of 9 female mice were used to extract the effective atomic number Zeff and the relative electron density ρe for each voxel in the images. To investigate the influence of the tissue compositions on the absorbed radiation dose for a typical kilovoltage photon beam, mass energy-absorption coefficients μen /ρ were calculated for 10 different tissues in each mouse. RESULTS: Differences between human and murine tissue compositions can lead to errors around 7...
November 30, 2018: British Journal of Radiology
https://www.readbyqxmd.com/read/30496879/dosimetric-impact-of-mri-distortions-a-study-on-head-and-neck-cancers
#8
Mary Adjeiwaah, Mikael Bylund, Josef A Lundman, Karin Söderström, Björn Zackrisson, Joakim H Jonsson, Anders Garpebring, Tufve Nyholm
PURPOSE: To evaluate the effect of magnetic resonance imaging (MRI) geometric distortions on head and neck radiotherapy treatment planning (RTP) in for an MRI-only RTP. We also assessed the potential benefits of patient-specific shimming to reduce the magnitude of MR distortions for a 3 T scanner. MATERIALS AND METHODS: Using an in-house Matlab algorithm, shimming within entire imaging volumes and user-defined region of interest (ROI) were simulated. We deformed 21 patient CTs (CT) with MR distortion fields (gradient nonlinearity and patient-induced susceptibility effects) to create distorted CT (dCT) images using bandwidths of 122 and 488 Hz/mm at 3 T...
November 26, 2018: International Journal of Radiation Oncology, Biology, Physics
https://www.readbyqxmd.com/read/30483477/evaluation-of-proton-therapy-accuracy-using-a-pmma-phantom-and-pet-prediction-module
#9
Junyu Zhang, Yan Lu, Wenchien Hsi, Jiangang Zhang, Yinxiangzi Sheng, Leijun Shi, Weiwei Wang, Jiade Lu, Rong Zhou, Jingyi Cheng
Purpose: Positron emission tomography (PET) scanning is a widely used method of proton therapy verification. In this study, a proton radiotherapy accuracy verification process was developed by comparing predicted and measured PET data to verify the correctness of PET prediction and was tested at the Shanghai Proton and Heavy Ion Center. Method: Irradiation was performed on a polymethyl methacrylate (PMMA) phantom. There were two dose groups, to which 2 and 4 Gy doses were delivered, and each dose group had different designed dose depths ranging from 5 to 20 cm...
2018: Frontiers in Oncology
https://www.readbyqxmd.com/read/30479293/the-utility-of-penile-bulb-contouring-to-localise-the-prostate-apex-as-compared-to-urethrography
#10
Michael I Lock, Alicia Heinrichs, Gaurav Bhattacharya, Ellen Cusano, Robert Ash, David D'Souza, George Rodrigues, Robert Dinniwell, Varagur Venkatesan, Glenn Bauman, Eugene Wong
PURPOSE: High-precision radiotherapy relies on accurate anatomic localisation. Urethrography is often used to localise the prostatic apex. However, urethrography is an invasive localisation procedure and may introduce a systemic error. The penile bulb (PB) is contoured to minimise the risk of erectile dysfunction. The purpose of this study is to assess the value of using the PB, as an alternative to urethrography, to localise the prostate. METHODS AND MATERIALS: The PB was localised on 10 patients treated with simplified intensity-modulated arc radiotherapy at computed tomography simulation during treatment weeks 1 and 7...
March 2018: Journal of Medical Imaging and Radiation Sciences
https://www.readbyqxmd.com/read/30474353/dosimetric-evaluation-of-an-atlas-based-synthetic-ct-generation-approach-for-mr-only-radiotherapy-of-pelvis-anatomy
#11
Reza Farjam, Neelam Tyagi, Joseph O Deasy, Margie A Hunt
PURPOSE: To investigate the potential of an atlas-based approach in generation of synthetic CT for pelvis anatomy. METHODS: Twenty-three matched pairs of computed tomography (CT) and magnetic resonance imaging (MRI) scans were selected from a pool of prostate cancer patients. All MR scans were preprocessed to reduce scanner- and patient-induced intensity inhomogeneities and to standardize their intensity histograms. Ten (training dataset) of 23 pairs were then utilized to construct the coregistered CT-MR atlas...
November 26, 2018: Journal of Applied Clinical Medical Physics
https://www.readbyqxmd.com/read/30471129/learning-based-cbct-correction-using-alternating-random-forest-based-on-auto-context-model
#12
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
https://www.readbyqxmd.com/read/30459454/evaluation-of-dynamic-tumor-tracking-intensity-modulated-radiotherapy-for-locally-advanced-pancreatic-cancer
#13
Akira Nakamura, Masahiro Hiraoka, Satoshi Itasaka, Mitsuhiro Nakamura, Mami Akimoto, Yoshitomo Ishihara, Nobutaka Mukumoto, Yoko Goto, Takahiro Kishi, Michio Yoshimura, Yukinori Matsuo, Shinsuke Yano, Takashi Mizowaki
Intensity-modulated radiotherapy (IMRT) is now regarded as an important treatment option for patients with locally advanced pancreatic cancer (LAPC). To reduce the underlying tumor motions and dosimetric errors during IMRT as well as the burden of respiratory management for patients, we started to apply a new treatment platform of the dynamic tumor dynamic tumor-tracking intensity-modulated radiotherapy (DTT-IMRT) using the gimbaled linac, which can swing IMRT toward the real-time tumor position under patients' voluntary breathing...
November 20, 2018: Scientific Reports
https://www.readbyqxmd.com/read/30457119/validation-of-fast-motion-including-dose-reconstruction-for-proton-scanning-therapy-in-the-liver
#14
Emma Colvill, Jørgen B B Petersen, Rune Hansen, Esben Worm, Simon Skouboe, Morten Høyer, Per R Poulsen
This study validates a method of fast motion-including dose reconstruction for proton pencil beam scanning in the liver. The method utilizes a commercial treatment planning system (TPS) and calculates the delivered dose for any translational 3D target motion. Data from ten liver patients previously treated with photon radiotherapy with intrafraction tumour motion monitoring were used. The dose reconstruction method utilises an in-house developed program to incorporate beam's-eye-view tumour motion by shifting each spot in the opposite direction of the tumour and in-depth motion as beam energy changes for each spot...
November 20, 2018: Physics in Medicine and Biology
https://www.readbyqxmd.com/read/30444161/mri-based-tumor-inter-fraction-motion-statistics-for-rectal-cancer-boost-radiotherapy
#15
Jean-Paul J E Kleijnen, Bram van Asselen, Robbe Van den Begin, Martijn Intven, Johannes P M Burbach, Onne Reerink, Marielle E P Philippens, Mark de Ridder, Jan J W Lagendijk, Bas W Raaymakers
BACKGROUND: In patients diagnosed with rectal cancer, dose escalation is currently being investigated in a large number of studies. Since there is little known on gross tumor volume (GTV) inter-fraction motion for rectal cancer, a wide variety in margins is used. Purpose of this study is to quantify GTV inter-fraction motion statistics on different timescales and to give estimates of planning target volume (PTV) margins. MATERIAL AND METHODS: Thirty-two patients, diagnosed with rectal cancer, were included...
November 16, 2018: Acta Oncologica
https://www.readbyqxmd.com/read/30440532/a-visual-probe-positioning-tool-for-4d-ultrasound-guided-radiotherapy
#16
Svenja Ipsen, Ralf Bruder, Ivo Kuhlemann, Philipp Jauer, Laura Motisi, Florian Cremers, Floris Ernst, Achim Schweikard
Ultrasound (US) guidance is a rapidly growing area in image-guided radiotherapy. For motion compensation, the therapy target needs to be visualized with the US probe to continuously determine its position and adapt for shifts. While US has obvious benefits such as real-time capability and proven safety, one of the main drawbacks to date is its user dependency - high quality results require long years of clinical experience. To provide positioning assistance for the setup of US equipment by non-experts, we developed a visual guidance tool combining real-time US volume and CT visualization in a geometrically calibrated setup...
July 2018: Conference Proceedings: Annual International Conference of the IEEE Engineering in Medicine and Biology Society
https://www.readbyqxmd.com/read/30418942/robust-radiotherapy-planning
#17
Jan Unkelbach, Markus Alber, Mark Bangert, Rasmus Bokrantz, Timothy C Y Chan, Joseph O Deasy, Albin Fredriksson, Bram L Gorissen, Marcel van Herk, Wei Liu, Houra Mahmoudzadeh, Omid Nohadani, Jeffrey V Siebers, Marnix Witte, Huijun Xu
Motion and uncertainty in radiotherapy is traditionally handled via margins. The clinical target volume (CTV) is expanded to a larger planning target volume (PTV), which is irradiated to the prescribed dose. However, the PTV concept has several limitations, especially in proton therapy. Therefore, robust and probabilistic optimization methods have been developed that directly incorporate motion and uncertainty into treatment plan optimization for intensity modulated radiotherapy (IMRT) and intensity modulated proton therapy (IMPT)...
November 12, 2018: Physics in Medicine and Biology
https://www.readbyqxmd.com/read/30405837/how-much-margin-do-we-need-for-pelvic-lymph-nodes-irradiation-in-the-era-of-igrt
#18
Zhikai Liu, Xia Liu, Fuquan Zhang, Ke Hu
Background and purpose: Image guided radiotherapy (IGRT) without 6 degree of freedom couch can only correct the translational setup errors of pelvic radiotherapy. But errors introduced by rotation and deformation of CTV can't be adjusted in most of IGRT systems. This article is to evaluate these errors and to provide recommendations on the margin needed in the era of IGRT. Material and methods: 218 patients who received pelvic radiotherapy in PUMC Hospital from 2012 to 2014 were included. A simulation CT and a CBCT were acquired for every patient...
2018: Journal of Cancer
https://www.readbyqxmd.com/read/30387364/development-and-validation-of-a-decision-support-tool-to-select-imrt-as-radiotherapy-treatment-planning-modality-for-patients-with-locoregionally-advanced-non-small-cell-lung-cancers-nsclc
#19
Raj Kumar Shrimali, Santam Chakraborty, Tapesh Bhattacharyya, Indranil Mallick, Rimpa Basu Achari, Sriram Prasath, B Arun, Anurupa Mahata, M Vidhya Shree, E Vishnupriya, Sanjoy Chatterjee
OBJECTIVE: Radiation planning for locally-advanced non-small cell lung cancer (NSCLC) can be time-consuming and iterative. Many cases cannot be planned satisfactorily using multisegment three-dimensional conformal radiotherapy (3DCRT). We sought to develop and validate a predictive model which could estimate the probability that acceptable target volume coverage would need intensity modulated radiotherapy (IMRT). METHODS: Variables related to the planning target volume (PTV) and topography were identified heuristically...
November 9, 2018: British Journal of Radiology
https://www.readbyqxmd.com/read/30385173/community-approach-for-reducing-small-field-measurement-errors-experience-over-24-centres
#20
Cinzia Talamonti, Serenella Russo, Maria Pimpinella, Maria Daniela Falco, Elisabetta Cagni, Stefania Pallotta, Michele Stasi, Pietro Mancosu
PURPOSE: The complexity of the modern Stereotactic Body Radiation Therapy (SBRT) techniques requires comprehensive quality assurance programs, to ensure the right treatment to the patient. Dosimetry of small radiation fields is a challenge especially for radiotherapy centres starting to work on this issue. The matter to be discussed here concerns the need of detailed measurement procedures and cross checks to be paired to the usual recommendations on detectors and correction factors. MATERIALS AND METHODS: The presented work involved 24 Italian radiotheraphy centres, with the specific purpose to minimize systematic errors in output factor measurements over different radiotherapy centres...
October 29, 2018: Radiotherapy and Oncology: Journal of the European Society for Therapeutic Radiology and Oncology
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