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Daisuke Kawahara, Shuichi Ozawa, Akito Saito, Teiji Nishio, Tomoki Kimura, Tatsuhiko Suzuki, Kazunari Hioki, Takeo Nakashima, Yoshimi Ohno, Yuji Murakami, Yasushi Nagata
PURPOSE: Stereotactic body radiation therapy (SBRT) combining trans-arterial chemoembolization (TACE) with Lipiodol is expected to improve local control. This study is aimed to estimate the dose enhancement in Lipiodol's proximity and to evaluate the dose calculation accuracy of the Acuros XB (AXB) algorithm and anisotropic analytical algorithm (AAA) in the Eclipse treatment planning system (TPS) (ver. 11, Varian Medical Systems, Palo Alto, USA), compared with that of the Monte Carlo (MC) calculation (using BEAMnrc/DOSXYZnrc code) for a virtual phantom and a treatment plan for liver SBRT after TACE...
January 2017: Medical Physics
Sanne Elsen, Evelyne Lerut, Frank Van Der Aa, Ben Van Cleynenbreugel, Hendrik Van Poppel, Peter De Witte
Photodynamic diagnosis (PDD) improves the detection of non-muscle-invasive bladder cancer (NMIBC). However, white-light (WL) cystoscopy remains the technique routinely used in urological clinics. A more cost-effective but equally performant alternative to PDD may encompass the use of an intense tumoritropic dye in combination with WL cystoscopy. Using a preclinical setting, we investigated the practical aspects of the use of Evans blue (EB) dye for the possible future detection of NMIBC using WL cystoscopy...
December 2016: Molecular and Clinical Oncology
Anthony Lemaire, Viktor Dombrovskiy, Siavash Saadat, George Batsides, Aziz Ghaly, Alan Spotnitz, Leonard Y Lee
BACKGROUND: Patients with infective endocarditis (IE) are at high risk for post-operative morbidity and death, which might be associated with drug abuse. The purpose of this study is to evaluate the impact of drug dependence on outcomes in patients who have IE and undergo valvular surgery (VS). PATIENTS AND METHODS: The Nationwide/National Inpatient Sample 2001-2012 was queried to select patients with IE who had elective VS using International Classification of Diseases, Ninth Revision, Clinical Modification diagnosis and procedure codes...
January 18, 2017: Surgical Infections
Kevin A Wunderle, Andrew R Godley, Zhilei Liu Shen, Joseph T Rakowski, Frank F Dong
PURPOSE: In this investigation, we sought to characterize X-ray beam qualities and quantify percent depth dose (PDD) curves for fluoroscopic X-ray beams incorporating added copper (Cu) filtration, such as those commonly used in fluoroscopically guided interventions (FGI). The intended application of this research is for dosimetry in soft tissue from FGI procedures using these data. METHODS: All measurements in this study were acquired on a Siemens (Erlangen, Germany) Artis zeego fluoroscope...
January 17, 2017: Medical Physics
Brian Spencer, Elvira Valera, Edward Rockenstein, Cassia Overk, Michael Mante, Anthony Adame, Wagner Zago, Peter Seubert, Robin Barbour, Dale Schenk, Dora Games, Robert A Rissman, Eliezer Masliah
Neurodegenerative disorders such as Parkinson's Disease (PD), PD dementia (PDD) and Dementia with Lewy bodies (DLB) are characterized by progressive accumulation of α-synuclein (α-syn) in neurons. Recent studies have proposed that neuron-to-neuron propagation of α-syn plays a role in the pathogenesis of these disorders. We have previously shown that antibodies against the C-terminus of α-syn reduce the intra-neuronal accumulation of α-syn and related deficits in transgenic models of synucleinopathy, probably by abrogating the axonal transport and accumulation of α-syn in in vivo models...
January 13, 2017: Acta Neuropathologica Communications
Xin Ming, Yuanming Feng, Ransheng Liu, Chengwen Yang, Li Zhou, Hezheng Zhai, Jun Deng
The goal of this study is to present a generalized source model (GSM) for accurate Monte Carlo dose simulations of CT scans based solely on the measurement data without a priori knowledge of scanner specifications. The proposed generalized source model consists of an extended circular source located at x-ray target level with its energy spectrum, source distribution and fluence distribution derived from a set of measurement data conveniently available in the clinic. Specifically, the central axis percent depth dose (PDD) curves measured in water and the cone output factors measured in air were used to derive the energy spectrum and the source distribution respectively with a Levenberg-Marquardt algorithm...
January 12, 2017: Physics in Medicine and Biology
S Koren, J Kindler, A Guemnie Tafo, G Cohen, E Reich
PURPOSE: We propose the use of a HDR X-ray source collimator to apply a conformal, relatively small, radiation suitable for a single fraction with short delivery time. In addition, this technique can be applied using a radioactive source. METHODS: We have built a stainless steel 1.5 mm thick applicator, to accommodate the needle applicator of the Intra-Beam X-ray source. Additional cavity is created in the applicator to allow the hosting/nesting/positioning of a LED diode...
June 2016: Medical Physics
H Saleh, T Howlin, V Massey
PURPOSE: We were presented with a 9 month old boy with Relapsed Acute Myeloid Leukemia (AML) involving the skin. The plan was to treat the entire skin using 6 MeV electrons with the infant under complete anesthesia. The purpose of this work is to commission the 6 MeV electron beam and to develop a technique that can be used to deliver total skin dose to infants with minimal patient immobilization. METHODS: A baby mannequin phantom that mimics the child's length was used to determine the best technique to treat the infant...
June 2016: Medical Physics
H Safigholi, A S Meigooni, D Han, A Soliman, W Y Song
PURPOSE: To evaluate the possibility of utilizing the BEBIG HDR 60Co remote after-loading system for malignant skin surface treatment using Monte Carlo (MC) simulation technique. METHODS: First TG-43 parameters of BEBIG-Co-60 and Nucletron Ir-192-mHDR-V2 brachytherapy sources were simulated using MCNP6 code to benchmark the sources against the literature. Second a conical tungsten-alloy with 3-cm diameter of Planning-Target-Volume (PTV) at surface for use with a single stepping HDR source is designed...
June 2016: Medical Physics
C Lin, T Chao, C Lin, H Nien, P Tu, C Yueh, C Wu
PURPOSE: The current standard equipment for proton PDD measurement is multilayer-parallel-ion-chamber. Disadvantage of multilayer-parallel-ion-chamber is expensive and complexity manipulation. NIPAM-gel and Presage are options for PDD measurement. Due to different stopping power, the result of NIPAM-gel and Presage need to be corrected. This study aims to create a correction model for NIPAM-gel and Presage PDD measurement. METHODS: Standard water based PDD profiles of electron 6MeV, 12MeV, and proton 90MeV were acquired...
June 2016: Medical Physics
Z Grelewicz, B Lee, D Cutright, Z Kang, M Gopalakrishnan, V Sathiaseelan, H Zhang
PURPOSE: Superficial lesions in the conjunctiva are frequently treated with en face electrons, using a hanging block to spare dose to the lens of the eye. Dose to the tumor and lens depend on the design and setup of the block and supporting apparatus. We performed in phantom measurements in order to characterize the dose sparing effects of the block as well as the under-dosing effect under the supporting apparatus for 6 MeV treatment. METHODS: The commercial hanging block studied uses a 1...
June 2016: Medical Physics
S Prajapati, Y Yan, K Gifford
PURPOSE: To generate and validate a linac Monte Carlo (MC) model for surface dose prediction. METHODS: BEAMnrc V4-2.4.0 was used to model 6 and 18 MV photon beams for a commercially available linac. DOSXYZnrc V4-2.4.0 calculated 3D dose distributions in water. Percent depth dose (PDD) and beam profiles were extracted for comparison to measured data. Surface dose and at depths in the buildup region was measured with radiochromic film at 100 cm SSD for 4 × 4 cm(2) and 10 × 10 cm(2) collimator settings for open and MLC collimated fields...
June 2016: Medical Physics
S Mein, R Gunasingha, M Nolan, M Oldham, J Adamson
PURPOSE: X-PACT is an experimental cancer therapy where kV x-rays are used to photo-activate anti-cancer therapeutics through phosphor intermediaries (phosphors that absorb x-rays and re-radiate as UV light). Clinical trials in pet dogs are currently underway (NC State College of Veterinary Medicine) and an essential component is the ability to model the kV dose in these dogs. Here we report the commissioning and characterization of a Monte Carlo (MC) treatment planning simulation tool to calculate X-PACT radiation doses in canine trials...
June 2016: Medical Physics
A Tyagi, S Kaushik, R Punia, M Singh
PURPOSE: To study the dosimetric properties of cadmium free alloy which is used in compensator based IMRT. METHODS: A mixture of 30% of lead,52% of bismuth and 18% of tin was used to prepare alloy. We prepared slabs of different thicknesses ranging from 0.71 cm to 6.14 cm. Density of alloy was measured by Archimedes' principle using SI-234 Denver instrument and water as buoyant liquid. Transmission, linear attenuation coefficient (µ), tissue phantom ration (TPR), beam hardening, surface dose (Ds), percentage depth dose (PDD) and effect of scatter were measured and analyze for different field size and different thickness of compensator for 6 MV photon beam...
June 2016: Medical Physics
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
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
K Wunderle, A Godley, Z Shen, J Rakowski, F Dong
PURPOSE: The purpose of this investigation was to quantify percent depth dose (PDD) curves for fluoroscopic x-ray beam qualities incorporating added copper filtration. METHODS: A PTW (Freiburg, Germany) MP3 water tank was used with a Standard Imaging (Middleton, WI) Exradin Model 11 Spokas Chamber to measure PDD curves for 60, 80, 100 and 120 kVp x-ray beams with copper filtration ranging from 0.0-0.9 mm at 22cm and 42cm fields of view from 0 to 150 mm of water...
June 2016: Medical Physics
A Almonte, G Polanco, E Sanchez
PURPOSE: The aim of the present contribution was to measure the main dosimetric quantities of small fields produced by UNIQUE and evaluate its matching with the corresponding dosimetric data of one 21EX conventional linear accelerator (Varian) in operation at the same center. The second step was to evaluate comparative performance of the EDGE diode detector and the PinPoint micro-ionization chamber for dosimetry of small fields. METHODS: UNIQUE is configured with MLC (120 leaves with 0...
June 2016: Medical Physics
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
A Ghila, S Steciw, B Fallone, S Rathee
PURPOSE: Integrated linac-MR systems are uniquely suited for real time tumor tracking during radiation treatment. Understanding the magnetic field dose effects and incorporating them in treatment planning is paramount for linac-MR clinical implementation. We experimentally validated the EGSnrc dose calculations in the presence of a magnetic field parallel to the radiation beam travel. METHODS: Two cylindrical bore electromagnets produced a 0.21 T magnetic field parallel to the central axis of a 6 MV photon beam...
June 2016: Medical Physics
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