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https://www.readbyqxmd.com/read/28076291/individual-construction-of-freeform-fabricated-polycaprolactone-scaffolds-for-osteogenesis
#1
Lu Liu, Guixin Shi, Ying Cui, Hui Li, Zhengchao Li, Qiangcheng Zeng, Yong Guo
The construction of engineered bone mostly focuses on simulating the extracellular matrix (ECM) for proper biological activity. However, the complexity of architecture and the variability of the mechanical properties of natural bones are related to individual differences in age, nutritional state, mechanical loading and disease status. Defect substitutions should be normed with the host natural bone, balancing architectural and mechanical adaption, as well as biological activity. Using a freeform fabrication (FFF) method, we prepared polycaprolactone (PCL) scaffolds with different architectures...
January 11, 2017: Biomedizinische Technik. Biomedical Engineering
https://www.readbyqxmd.com/read/28048885/mo-d-brb-03-quality-assurance-of-sbrt
#2
J Roper
: Increased use of SBRT and hypofractionation in radiation oncology practice has posted a number of challenges to medical physicist, ranging from planning, image-guided patient setup and on-treatment monitoring, to quality assurance (QA) and dose delivery. This symposium is designed to provide current knowledge necessary for the safe and efficient implementation of SBRT in various linac platforms, including the emerging digital linacs equipped with high dose rate FFF beams. Issues related to 4D CT, PET and MRI simulations, 3D/4D CBCT guided patient setup, real-time image guidance during SBRT dose delivery using gated/un-gated VMAT/IMRT, and technical advancements in QA of SBRT (in particular, strategies dealing with high dose rate FFF beams) will be addressed...
June 2016: Medical Physics
https://www.readbyqxmd.com/read/28048645/su-f-t-404-dosimetric-advantages-of-flattening-free-beams-to-prone-accelerated-partial-breast-irradiation
#3
P Galavis, D Barbee, G Jozsef
PURPOSE: Prone accelerated partial breast irradiation (APBI) results in dose reduction to the heart and lung. Flattening filter free beams (FFF) reduce out of field dose due to the reduced scatter from the removal of the flattening filter and reduce the buildup region. The aim of this work is to evaluate the dosimetric advantages of FFF beams to prone APBI target coverage and reduction in dose to organs at risk. METHODS: Fifteen clinical prone APBI cases using flattened photon beams were retrospectively re-planned in Eclipse-TPS using FFF beams...
June 2016: Medical Physics
https://www.readbyqxmd.com/read/28048558/su-f-t-338-flattening-filter-free-photon-beams-can-achieve-the-same-plan-quality-as-conventional-flattened-beams-for-prostate-radiotherapy
#4
M Kolar, R Szwedowski, J Greskovich, P Xia
PURPOSE: Some modern linear accelerators are equipped with one low energy flat beam and two flattening filter free (FFF) beams at high and low energies. The purpose of this study is to investigate whether the high energy FFF beam can produce the same plan quality as the conventional low energy flat beam, using a volumetric modulated arc (VMAT) technique for prostate patients. METHODS: Ten prostate cancer patients were selected with a prescription of 78Gy. For each patient, three plans were created: (a) double arc flat 6MV plan used clinically; (b) double arc 10MV FFF plan; (c) single arc 10MV FFF plan...
June 2016: Medical Physics
https://www.readbyqxmd.com/read/28048513/su-c-202-07-protocol-and-hardware-for-improved-flood-field-calibration-of-truebeam-fff-cine-imaging
#5
J Adamson, A Faught, F Yin
PURPOSE: Flattening filter free photon energies are commonly used for high dose treatments such as SBRT, where localization accuracy is essential. Often, MV cine imaging may be employed to verify correct localization. TrueBeam Electronic Portal Imaging Devices (EPIDs) equipped with the 40×30cm(2) Image Detection Unit (IDU) are prone to image saturation at the image center especially for higher dose rates. While saturation often does not occur for cine imaging during treatment because the beam is attenuated by the patient, the flood field calibration is affected when the standard calibration procedure is followed...
June 2016: Medical Physics
https://www.readbyqxmd.com/read/28048483/su-f-t-488-comparison-of-the-tg-51-and-tg-51-addendum-calibration-protocols
#6
T McCaw, M Hwang, S Jang, M Huq
PURPOSE: To quantify differences between the TG51 and TG51 addendum calibration protocols. METHODS: Beam energies of 6X, 6XSRS, 10X, 15X, 23X, 6XFFF, and 10XFFF were calibrated following both the TG51 and TG51 addendum protocols using both a Farmer and a scanning ionization chamber with traceable absorbed dose-to-water calibrations. For the TG51 addendum procedure, the collimating jaws were positioned to define a 10×10cm(2) radiation field, a lead foil was only used for kQ measurements of FFF energies, and a volume-averaging correction was applied based on crossline and inline dose profiles...
June 2016: Medical Physics
https://www.readbyqxmd.com/read/28048475/su-f-t-522-dosimetric-study-of-junction-dose-in-double-isocenter-flatten-and-flatten-filter-free-imrt-and-vmat-plan-delivery
#7
K Samuvel, G Yadav, M Bhushan, S Tamilarasu, L Kumar, M Suhail
PURPOSE: To quantify the dosimetric accuracy of junction dose in double isocenter flattened and flatten filter free(FFF) intensity modulated radiation therapy(IMRT) and volumetric modulated arc therapy(VMAT) plan delivery using pelvis phantom. METHODS: Five large field pelvis patients were selected for this study. Double isocenter IMRT and VMAT treatment plans were generated in Eclipse Treatment planning System (V.11.0) using 6MV FB and FFF beams. For all the plans same distance 17...
June 2016: Medical Physics
https://www.readbyqxmd.com/read/28048457/su-f-t-551-beam-hardening-and-attenuation-of-photon-beams-using-integral-quality-monitor-in-radiotherapy
#8
B Casar, I Mendez Carot, P Peterlin
PURPOSE: Aim of the multi-centre study was to analyse beam hardening effect of the Integral Quality Monitor (IQM) for high energy photon beams used in radiotherapy with linear accelerators. Generic values for attenuation coefficient k(IQM) of IQM system were additionally investigated. METHODS: Beam hardening effect of the IQM system was studied for a set of standard nominal photon energies (6 MV-18 MV) and two flattening filter free (FFF) energies (6 MV FFF and 10 MV FFF)...
June 2016: Medical Physics
https://www.readbyqxmd.com/read/28048441/su-f-t-506-development-and-commissioning-of-the-effective-and-efficient-grid-therapy-using-high-dose-rate-flattening-filter-free-beam-and-multileaf-collimator
#9
M Liu, N Wen, C Beyer, F Siddiqui, I Chetty, B Zhao
PURPOSE: Treating bulky tumors with grid therapy (GT) has demonstrated high response rates. Long delivery time (∼15min), with consequent increased risk of intrafraction motion, is a major disadvantage of conventional MLC-based GT (MLC-GT). The goal of this study was to develop and commission a MLC-GT technique with similar dosimetric characteristics, but more efficient delivery. METHODS: Grid plan was designed with 10X-FFF (2400MU/min) beam and MLC in a commercial treatment planning system (TPS)...
June 2016: Medical Physics
https://www.readbyqxmd.com/read/28048436/su-c-201-02-dosimetric-verification-of-sbrt-with-fff-vmat-using-a-3-d-radiochromic-optical-ct-dosimetry-system
#10
Y Na, P Black, J Adamovics, C Wuu
PURPOSE: With an increasing use of small field size and high dose rate irradiation in the advances of radiotherapy techniques, such as stereotactic body radiotherapy (SBRT) and stereotactic radiosurgery (SRS), an in-depth quality assurance (QA) system is required. The purpose of this study is to investigate a high resolution optical CT-based 3D radiochromic dosimetry system for SBRT with intensity modulated radiotherapy (IMRT) and flattening filter free (FFF) volumetric modulated arc therapy (VMAT)...
June 2016: Medical Physics
https://www.readbyqxmd.com/read/28048363/su-f-t-518-development-and-characterization-of-a-gated-treatment-system-implemented-with-an-in-house-optical-tracking-system-and-the-elekta-response-interface
#11
B Barraclough, J Park, F Li, B Lu, J Li, C Liu, G Yan
PURPOSE: To report the development and characterization of the first in-house gating system implemented with an optical tracking system (OTS) and the Elekta Response™ interface. METHODS: The Response™ connects a patient tracking system with a linac, enabling the tracking system to control radiation delivery. The developed system uses an in-house OTS to monitor patient breathing. The OTS consists of two infrared-based cameras, tracking markers affixed on patient...
June 2016: Medical Physics
https://www.readbyqxmd.com/read/28048339/su-f-t-621-impact-of-vacuum-and-treatment-couch-on-surface-dose-in-stereotactic-body-radiation-therapy-with-and-without-a-flattening-filter
#12
H T Lan, S H Lu, S H Kuo, Y C Tsai, L H Chen, S Y Wen, C W Wang
PURPOSE: When treating lung cancer patients with stereotactic body radiation therapy (SBRT), better immobilization is needed for accurate delivery of high-dose radiation. However, using a treatment couch (TrueBeamTM) and vacuum bag (BlueBAGTM) may increase the surface dose and skin toxicity. This study investigated the influence of couch and vacuum bag on the surface dose. METHODS: The relative surface dose (D0 /DMAX) was measured in an ion-chamber (Markus-type PTW, 0...
June 2016: Medical Physics
https://www.readbyqxmd.com/read/28048309/su-f-j-179-commissioning-dosimetric-data-of-a-new-2-5-megavoltage-imaging-beam-from-a-truebeam-linear
#13
G Ding
PURPOSE: Recently a new 2.5 megavoltage imaging beam has become available in a TrueBeam linear accelerator for image guidance. There is limited information available related to the beam characteristics. Commissioning dosimetric data of the new imaging is necessary for configuration of the beam in a treatment planning system in order to calculate imaging doses to patients resulting from this new imaging beam. The purpose of this study is to provide measured commissioning data recommended for a beam configuration in a treatment planning system...
June 2016: Medical Physics
https://www.readbyqxmd.com/read/28048298/su-f-j-99-dose-accumulation-and-evaluation-in-lung-sbrt-among-all-phases-of-respiration
#14
J D Azcona, J Burguete, B Barbes, J Aristu, M Moreno, A Zubiria, P Arce, J I Lagares
PURPOSE: To calculate the total planning dose on lung tumors (GTV) by accumulating the dose received in all respiration phases. METHODS: A patient 4D planning CT (phase-binned, from a Siemens Somatom CT) was used to locate the GTV of a lung tumor in all respiratory phases with Pinnacle (v9.10). GTV contours defined in all phases were projected to the reference phase, where the ITV was defined. Centroids were calculated for all the GTV projections. No deformation or rotation was taken into account...
June 2016: Medical Physics
https://www.readbyqxmd.com/read/28048128/mo-d-brb-00-sbrt-workflow-overview
#15
Lei Xing
: Increased use of SBRT and hypofractionation in radiation oncology practice has posted a number of challenges to medical physicist, ranging from planning, image-guided patient setup and on-treatment monitoring, to quality assurance (QA) and dose delivery. This symposium is designed to provide current knowledge necessary for the safe and efficient implementation of SBRT in various linac platforms, including the emerging digital linacs equipped with high dose rate FFF beams. Issues related to 4D CT, PET and MRI simulations, 3D/4D CBCT guided patient setup, real-time image guidance during SBRT dose delivery using gated/un-gated VMAT/IMRT, and technical advancements in QA of SBRT (in particular, strategies dealing with high dose rate FFF beams) will be addressed...
June 2016: Medical Physics
https://www.readbyqxmd.com/read/28048124/su-g-brb-05-automation-of-the-photon-dosimetric-quality-assurance-program-of-a-linear-accelerator
#16
S Lebron, B Lu, G Yan, J Li, C Liu
PURPOSE: To develop an automated method to calculate a linear accelerator (LINAC) photon radiation field size, flatness, symmetry, output and beam quality in a single delivery for flattened (FF) and flattening-filter-free (FFF) beams using an ionization chamber array. METHODS: The proposed method consists of three control points that deliver 30×30, 10×10 and 5×5cm(2) fields (FF or FFF) in a step-and-shoot sequence where the number of monitor units is weighted for each field size...
June 2016: Medical Physics
https://www.readbyqxmd.com/read/28048033/su-f-t-87-comparison-of-advanced-radiotherapy-techniques-for-post-mastectomy-breast-cancer-patients
#17
D Heins, R Zhang, K Hogstrom, M Sanders
PURPOSE: To determine if bolus electron conformal therapy (Bolus-ECT) combined with intensity modulated x-ray therapy (IMXT) and flattening filter free volumetric modulated arc therapy (FFF-VMAT (6x and 10x)) can maintain equal or better dose coverage than standard volumetric modulated arc therapy (Std-VMAT) while reducing doses to organs at risk (OARs). METHODS: Bolus-ECT with IMXT, FFF-VMAT, and Std-VMAT treatment plans were produced for ten post-mastectomy radiotherapy (PMRT) patients previously treated at our clinic...
June 2016: Medical Physics
https://www.readbyqxmd.com/read/28048021/mo-fg-campus-tep2-03-multi-criteria-optimization-using-taguchi-method-for-srs-of-multiple-lesions-by-single-isocenter
#18
S Alani, N Honig, A Schlocker, B Corn
PURPOSE: This study utilizes the Taguchi Method to evaluate the VMAT planning parameters of single isocenter treatment plans for multiple brain metastases. An optimization model based on Taguchi and utility concept is employed to optimize the planning parameters including: arc arrangement, calculation grid size, calculation model, and beam energy on multiple performance characteristics namely conformity index and dose to normal brain. METHODS: Treatment plans, each with 4 metastatic brain lesions were planned using single isocenter technique...
June 2016: Medical Physics
https://www.readbyqxmd.com/read/28047941/su-f-t-372-surface-and-peripheral-dose-in-compensator-based-fff-beam-imrt
#19
D Zhang, V Feygelman, E Moros, K Latifi, S Hoffe, J Frakes, G Zhang
PURPOSE: Flattening filter free (FFF) beams produce higher dose rates. Combined with compensator IMRT techniques, the dose delivery for each beam can be much shorter compared to the flattened beam MLC-based or compensator-based IMRT. This 'snap shot' IMRT delivery is beneficial to patients for tumor motion management. Due to softer energy, surface doses in FFF beam treatment are usually higher than those from flattened beams. Because of less scattering due to no flattening filter, peripheral doses are usually lower in FFF beam treatment...
June 2016: Medical Physics
https://www.readbyqxmd.com/read/28047904/su-f-t-305-clinical-effects-of-dosimetric-leaf-gap-dlg-values-between-matched-varian-truebeam-tb-linacs
#20
D Mihailidis, J Mallah, D Zhu
PURPOSE: The dosimetric leaf gap (DLG) is an important parameter to be measured for dynamic beam delivery of modern linacs, like the Varian Truebeam (TB). The clinical effects of DLG-values on IMRT and/or VMAT commissioning of two "matched" TB linacs will be presented. METHODS AND MATERIALS: The DLG values on two TB linacs were measured for all energy modalities (filtered and FFF-modes) as part of the dynamic delivery mode commissioning (IMRT and/or VMAT. After the standard beam data was modeled in eclipse treatment planning system (TPS) and validated, IMRT validation was performed based on TG1191 benchmark, IROC Head-Neck (H&N) phantom and sample of clinical cases, all measured on both linacs...
June 2016: Medical Physics
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