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Radiochromic film

Borowicz Dorota Maria, Malicki Julian, Mytsin Gennady, Shipulin Konstantin
AIM: To evaluate the impact of radiochromic film positioning relative to the central beam axis (CAX) in proton beam therapy. Secondarily, to compare the dosimetric measurements obtained by RTQA and EBT film and to compare these to the doses calculated by the treatment planning system (TPS). METHODS: EBT and RTQA dosimetric radiochromic films were immersed in a water phantom and irradiated with a proton beam. The films were placed parallel to the CAX and at a 5º angle on the horizontal plane to assess the effect of film inclination on Bragg peak profiles...
February 14, 2017: Medical Physics
Tatsuhiro Gotanda, Toshizo Katsuda, Rumi Gotanda, Tadao Kuwano, Takuya Akagawa, Nobuyoshi Tanki, Akihiko Tabuchi, Tetsunori Shimono, Yasuyuki Kawaji
Radiochromic film dosimeters have a disadvantage in comparison with an ionization chamber in that the dosimetry process is time-consuming for creating a density-absorbed dose calibration curve. The purpose of this study was the development of a simplified method of creating a density-absorbed dose calibration curve from radiochromic film within a short time. This simplified method was performed using Gafchromic EBT3 film with a low energy dependence and step-shaped Al filter. The simplified method was compared with the standard method...
October 2016: Journal of Medical Physics
Michele Zeverino, Maud Jaccard, David Patin, Nick Ryckx, Maud Marguet, Constantin Tuleasca, Luis Schiappacasse, Jean Bourhis, Marc Levivier, Francois O Bochud, Raphaël Moeckli
PURPOSE: The Leksell Gamma Knife (LGK) Icon has been recently introduced to provide Gamma Knife technology with frameless stereotactic treatments which use an additional cone-beam CT (CBCT) imaging system and a motion tracking system (IFMM, Intra-Fraction Motion Management). The system was commissioned for the treatment unit itself as well as the imaging system. METHODS: The LGK Icon was calibrated using an A1SL ionization chamber. EBT3 radiochromic films were employed to independently check the machine calibration, to measure the relative output factors (ROFs) and to collect dose distributions...
December 10, 2016: Medical Physics
Blake R Smith, John A Micka, Manik Aima, Larry A DeWerd, Wesley S Culberson
PURPOSE: To perform an in-air air-kerma strength (SK) calibration of the Bebig model Ir2.A85-2 192Ir high-dose rate (HDR) brachytherapy source manufactured by Mallinckrodt Medical (Westerduinweg, Germany) with the NIST-traceable seven-distance technique established by the University of Wisconsin. A comparison was made between the reference air-kerma rate (RAKR) reported on a certificate from the Physikalisch-Technische Bundesanstalt (Berlin, Germany) (PTB) primary laboratory and the SK determined at the University of Wisconsin Madison Radiation Research Center (UWMRRC)...
January 2017: Medical Physics
I Brezovich, X Wu, R Popple, S Shen, R Cardan, M Bolding, J Fiveash, J Kraus, S Spencer
PURPOSE: To test spatial and dosimetric accuracy of small cranial target irradiation based on 1.5 T MRI scans using static arcs with MLC-defined fields METHODS: A plastic (PMMA) phantom simulating a small brain lesion was mounted on a GammaKnife headframe equipped with MRI localizer. The lesion was a 3 mm long, 3.175 mm diameter cylindrical cavity filled with MRI contrast. Radiochromic film passing through the cavity was marked with pin pricks at the cavity center. The cavity was contoured on an MRI image and fused with CT to simulate treatment of a lesion not visible on CT...
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
M Chan, C Chen, J Li, X Tang, X Li, G Tang, D Mah
PURPOSE: Radiochromic film for spot-scanning QA provides high spatial resolution and efficiency gains from one-shot irradiation for multiple depths. However, calibration can be a tedious procedure which may limit widespread use. Moreover, since there may be an energy dependence, which manifests as a depth dependence, this may require additional measurements for each patient. We present a one-scan protocol to simplify the procedure. METHODS: We performed the calibration using an EBT3 film at depths of 18, 20, 24cm of Plastic Water exposed by a 6-level step-wedge plan on a Proteus Plus proton system (IBA, Belgium)...
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
C Ng, V Lee, S Chan, F Lee, R Ngan
PURPOSE: Accuracy of radiotherapy dose calculation in patients with surgical implants is complicated by two factors. First is the accuracy of CT number, second is the dose calculation accuracy. We compared measured dose with dose calculated on CT images reconstructed with FBP and an artifact reduction algorithm (OMAR, Philips) for a phantom with high density inserts. Dose calculation were done with Varian AAA and AcurosXB. METHODS: A phantom was constructed with solid water in which 2 titanium or stainless steel rods could be inserted...
June 2016: Medical Physics
J Maurer, B Sintay, M Manning, D Wiant, H Liu
PURPOSE: This study evaluates a novel algorithm that can be used with any treatment planning system for simple and rapid generation of stereotactic radiosurgery (SRS) plans for treating multiple brain metastases using a single isocenter dynamic conformal arc (DCA) approach. This technique is compared with a single isocenter volumetric modulated arc therapy (VMAT) technique in terms of delivery time, conformity, low dose spread and delivery accuracy. METHODS: Five patients, with a total of 37 (5 - 11) targets were planned using a previously published method for generating optimal VMAT plans and using the proposed DCA algorithm...
June 2016: Medical Physics
J Aubry, K Zerouali
PURPOSE: To evaluate the accuracy and precision of radiochromic films EBT-XD for quality control of stereotaxic body radiation therapy (SBRT) and stereotactic radiosurgery (SRS) plan delivery. METHODS: A film cut in 3×10 cm2 strips was irradiated from 0 to 20 Gy in increments of 1 to 1.5 Gy using a 15 MeV electron beam. Triple-channel film calibration was completed 24 hours later by scanning the film strips on an Epson 10000XL scanner using a well-defined protocol...
June 2016: Medical Physics
O Chibani, F Tahanout, C Ma
PURPOSE: To commission a new MLC model for the GEPTS Monte Carlo system. The model is based on the concept of leaves and interleaves effective densities METHODS: GEPTS is a Monte Carlo system to be used for external beam planning verification. GEPTS incorporates detailed photon and electron transport algorithms (Med.Phys. 29, 2002, 835). A new GEPTS model for the Varian Millennium MLC is presented. The model accounts for: 1) thick (1 cm) and thin (0.5 cm) leaves, 2) tongue-and-groove design, 3) High-Transmission (HT) and Low-Transmission (LT) interleaves, and 4) rounded leaf end...
June 2016: Medical Physics
J Rosenfield, X Yang, X Dong, E Elder, K Higgins, A Dhabaan
PURPOSE: To investigate potential dosimetrical differences between the Acuros XB (AXB) and AAA dose calculation algorithms, with a specific focus on lung SBRT treatments involving inherently high degrees of anatomical heterogeneity, small field sizes, and varying tumor locations relative to critical structures. METHODS: A cohort of 20 SBRT patients treated in our clinic was selected to include varying lung tumor locations. For each patient, the Eclipse treatment planning system was employed to generate a lung SBRT plan using the AXB dose calculation algorithm, in addition to the AAA plan previously calculated for clinical use...
June 2016: Medical Physics
H Jin, S Ahmad, Y Chen, V Keeling, A Lau, M Islam, C Ferreira, S Ferguson
PURPOSE: To report the detailed commissioning experience for a compact double-scattering Mevion S250 proton therapy system at a University Cancer Center site. METHODS: The commissioning of the proton therapy system mainly consisted of ensuring integrity of mechanical and imaging system, beam data collection, and commissioning of a treatment planning system (TPS). First, mechanical alignment and imaging were tested including safety, interlocks, positional accuracy of couch and gantry, image quality, mechanical and imaging isocenter and so on...
June 2016: Medical Physics
G Cui, J Ha, S Zhou, J Cui, A Shiu
PURPOSE: To examine and validate the absolute dose for total skin electron therapy (TSET) through an end-to-end test with a Rando phantom using optically stimulated luminescent dosimeters (OSLDs) and EBT3 radiochromic films. METHODS: A Varian Trilogy linear accelerator equipped with the special procedure 6 MeV HDTSe- was used to perform TSET irradiations using a modified Stanford 6-dual-field technique. The absolute dose was calibrated using a Markus ion chamber at a reference depth of 1...
June 2016: Medical Physics
D Granero, C Candela-Juan, J Vijande, F Ballester, J Perez-Calatayud, D Jacob, F Mourtada
PURPOSE: Utilization of HDR brachytherapy treatment of skin lesions using collimated applicators, such as the Valencia or Leipzig is increasing. These applicators are made of cup-shaped tungsten material in order to focalize the radiation into the lesion and to protect nearby tissues. These applicators have an attachable plastic cap that removes secondary electrons generated in the applicator and flattens the treatment surface. The purpose of this study is to examine the dosimetric impact of this cap, and the effect if the cap is not placed during the HDR fraction delivery...
June 2016: Medical Physics
A Jones, A Pasciak
PURPOSE: The purpose of this study was to determine if a relationship between indirect dose metrics and PSD could be established for fluoroscopically-guided interventional cardiology procedures. METHODS: PSD were measured directly using XR-RV3 radiochromic film for 94 consecutive fluoroscopically guided interventional cardiology procedures performed at two sites. Procedures were both diagnostic and therapeutic in nature. Radiation dose structured reports (RDSR) were collected for each procedure and used to calculate indirect estimates of PSD which were compared to the measured PSD...
June 2016: Medical Physics
T McCaw, S Jang, M Huq
PURPOSE: This work investigated the development of EBT3 film as a function of dose rate, and also the accuracy of a commercial calibrationrescaling analysis method, to determine potential application to patientspecific QA of CyberKnife MLC treatments. METHODS: EBT3 films were exposed to 300cGy at dose rates ranging from 5-300cGy/min, and scanned repeatedly from 2-5760min after exposure using a flatbed scanner. All other films were scanned 1 and 24hr after exposure...
June 2016: Medical Physics
E Johnson, F Misgina
PURPOSE: To study the effect of the Varian carbon fiber couch top on surface dose for patients being treated using single PA beams in the supine position and to identify simple methods for surface dose reduction. METHODS: Measurements of surface dose were obtained in Solid Water phantoms using both a parallel plate ionization chamber (PTW Advanced Markus) and EBT2 Radiochromic films for both 6 and 10MV photons. All measurements were referenced to a depth considered a typical for PA Spine fields...
June 2016: Medical Physics
R Underwood
PURPOSE: To determine the feasibility of using radiochromic and radiographic film with Pipspro software for quality assurance of linear accelerators with no on-board imaging. METHODS: The linear accelerator being used is a Varian Clinac 21EX. All IGRT is performed using the BrainLab ExacTrac system. Because of the lack of on board imaging, certain monthly and annual TG-142 quality assurance tests are more difficult to perform and analyze to a high degree of accuracy...
June 2016: Medical Physics
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