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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
J Kranz, G Maurer, U Maurer, O Deserno, S Schulte, J Steffens
BACKGROUND: A urethral stricture is a scar of the urethral epithelium which can cause obstructive voiding dysfunction with consequential damage of the upper urinary tract. Almost 45% of all strictures are iatrogenic; they develop in 2-9% of patients after radical prostatectomy, but can also occur after prostate cancer radiotherapy. This study provides 5‑year data of a certified prostate cancer center (PKZ) in terms of urethral strictures. MATERIALS AND METHODS: Between 01/2008 and 12/2012 a total of 519 men were irradiated for prostate cancer (LDR and HDR brachytherapy as well as external beam radiation)...
January 19, 2017: Der Urologe. Ausg. A
Michail Zaboikin, Tatiana Zaboikina, Carl Freter, Narasimhachar Srinivasakumar
Genome editing using transcription-activator like effector nucleases or RNA guided nucleases allows one to precisely engineer desired changes within a given target sequence. The genome editing reagents introduce double stranded breaks (DSBs) at the target site which can then undergo DNA repair by non-homologous end joining (NHEJ) or homology directed recombination (HDR) when a template DNA molecule is available. NHEJ repair results in indel mutations at the target site. As PCR amplified products from mutant target regions are likely to exhibit different melting profiles than PCR products amplified from wild type target region, we designed a high resolution melting analysis (HRMA) for rapid identification of efficient genome editing reagents...
2017: PloS One
Zhengguo Li, Zhe Wei, Changyun Wen, Jinghong Zheng
Multi-scale exposure fusion is an effective image enhancement technique for a high dynamic range (HDR) scene. In this paper, a new multi-scale exposure fusion algorithm is proposed to merge differently exposed low dynamic range (LDR) images by using the weighted guided image filter (WGIF) to smooth the Gaussian pyramids of weight maps for all the LDR images. Details in the brightest and darkest regions of the HDR scene are preserved better by the proposed algorithm without relative brightness change in the fused image...
January 16, 2017: IEEE Transactions on Image Processing: a Publication of the IEEE Signal Processing Society
Renan B Sper, Sehwon Koh, Xia Zhang, Sean Simpson, Bruce Collins, Jeff Sommer, Robert M Petters, Ignacio Caballero, Jeff L Platt, Jorge A Piedrahita
Transgenic pigs have become an attractive research model in the field of translational research, regenerative medicine, and stem cell therapy due to their anatomic, genetic and physiological similarities with humans. The development of fluorescent proteins as molecular tags has allowed investigators to track cell migration and engraftment levels after transplantation. Here we describe the development of two transgenic pig models via SCNT expressing a fusion protein composed of eGFP and porcine Histone 2B (pH2B)...
2017: PloS One
Grace Gwe-Ya Kim
: Failure Mode and Effects Analysis (FMEA) originated as an industrial engineering technique used for risk management and safety improvement of complex processes. In the context of radiotherapy, the AAPM Task Group 100 advocates FMEA as the framework of choice for establishing clinical quality management protocols. However, there is concern that widespread adoption of FMEA in radiation oncology will be hampered by the perception that implementation of the tool will have a steep learning curve, be extremely time consuming and labor intensive, and require additional resources...
June 2016: Medical Physics
K Harpool, T De La Fuente Herman, S Ahmad, I Ali
PURPOSE: To evaluate the performance of a two-dimensional (2D) array-diode- detector for geometric and dosimetric quality assurance (QA) tests of high-dose-rate (HDR) brachytherapy with an Ir-192-source. METHODS: A phantom setup was designed that encapsulated a two-dimensional (2D) array-diode-detector (MapCheck2) and a catheter for the HDR brachytherapy Ir-192 source. This setup was used to perform both geometric and dosimetric quality assurance for the HDR-Ir192 source...
June 2016: Medical Physics
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
C Chatzipapas, P Papadimitroulas, G Loudos, N Papanikolaou, G Kagadis
PURPOSE: Pediatric tumors are generally treated with multi-modal procedures. Brachytherapy can be used with pediatric tumors, especially given that in this patient population low toxicity on normal tissues is critical as is the suppression of the probability for late malignancies. Our goal is to validate the GATE toolkit on realistic brachytherapy applications, and evaluate brachytherapy plans on pediatrics for accurate dosimetry on sensitive and critical organs of interest. METHODS: The GATE Monte Carlo (MC) toolkit was used...
June 2016: Medical Physics
G Jozsef
PURPOSE: To build a test device for HDR afterloaders capable of checking source positions, times at positions and estimate the activity of the source. METHODS: A catheter is taped on a plastic scintillation sheet. When a source travels through the catheter, the scintillator sheet lights up around the source. The sheet is monitored with a video camera, and records the movement of the light spot. The center of the spot on each image on the video provides the source location, and the time stamps of the images can provide the dwell time the source spend in each location...
June 2016: Medical Physics
J Prisciandaro
: Brachytherapy has proven to be an effective treatment option for prostate cancer. Initially, prostate brachytherapy was delivered through permanently implanted low dose rate (LDR) radioactive sources; however, high dose rate (HDR) temporary brachytherapy for prostate cancer is gaining popularity. Needle insertion during prostate brachytherapy is most commonly performed under ultrasound (U/S) guidance; however, treatment planning may be performed utilizing several imaging modalities either in an intra- or post-operative setting...
June 2016: Medical Physics
A Babier, C Joshi
PURPOSE: In prostate HDR brachytherapy dose distributions are highly sensitive to changes in prostate volume and catheter displacements. We investigate the maximum deformations in implant geometry before planning objectives are violated. METHODS: A typical prostate Ir-192 HDR brachytherapy reference plan was calculated on the Oncentra planning system, which used CT images from a tissue equivalent prostate phantom (CIRS Model 053S) embedded inside a pelvis wax phantom...
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
M Shojaei, N Dumitru, S Pella
PURPOSE: High dose rate brachytherapy is a highly localized radiation therapy that has a very high dose gradient. Thus one of the most important parts of the treatment is the immobilization. The smallest movement of the patient or applicator can result in dose variation to the surrounding tissues as well as to the tumor to be treated. We will revise the ML Cylinder treatments and their localization challenges. METHODS: A retrospective study of 25 patients with 5 treatments each looking into the applicator's placement in regard to the organs at risk...
June 2016: Medical Physics
I Veltchev, R Price, P Anderson, C Ma
PURPOSE: The dwell positions in the VariSourceIX HDR ring applicator are known to be somewhat inaccurate with observed deviations from the planned position of up to 5mm. The details of how to correct this issue are suggested by the vendor and the dosimetric impact on volumetric HDR plans varies from patient to patient. In this study we present our experience with correcting this issue, and discuss the impact on plan quality if the planned dwell positions were left unchanged. METHODS: A 60 degree ring was characterized using gafchromic film with the applicator in treatment orientation...
June 2016: Medical Physics
S Laoui, S Dietrich, V Sehgal, M Al-Ghazi
PURPOSE: Radiation dose delivery for endometrial cancer using HDR techniques is limited by dose to bladder and rectum. A dosimetric study was performed using Varian Capri vaginal brachytherapy applicator to determine the optimal channel configuration which minimizes dose to bladder and rectum, while providing good target coverage. METHODS: A total of 17 patients, 63 plans clinically delivered, and 252 simulated plans using Varian BrachyVision planning system were generated to investigate optimal channel configuration which results in minimum dose to bladder and rectum while providing adequate target coverage...
June 2016: Medical Physics
Y Zhou, J Tan, S Jiang, K Albuquerque, X Jia
PURPOSE: High dose rate (HDR) brachytherapy treatment planning is conventionally performed in a manual fashion. Yet it is highly desirable to perform computerized automated planning to improve treatment planning efficiency, eliminate human errors, and reduce plan quality variation. The goal of this research is to develop an automatic treatment planning tool for HDR brachytherapy with a cylinder applicator for vaginal cancer. METHODS: After inserting the cylinder applicator into the patient, a CT scan was acquired and was loaded to an in-house developed treatment planning software...
June 2016: Medical Physics
H Ji, V Lorio, G Cernica, J Han, M Nurhussien, N Nasr, R Hong
PURPOSE: Since 2008, over 700 patients received high dose rate (HDR) APBI treatment at Virginia Hospital Center. The complexity involved in the planning process demonstrated a broad variation between patient geometry across all applicators, in relation to anatomical regions of interest. A quality management program instituting various metrics was implemented in March 2013 with the goal of ensuring an optimal plan is achieved for each patient. METHODS: For each plan, an in-house complexity index, geometric conformity index, and plan quality index were defined...
June 2016: Medical Physics
M Borot de Battisti, B Denis de Senneville, M Maenhout, G Hautvast, D Binnekamp, J J W Lagendijk, M Van Vulpen, M A Moerland
PURPOSE: This study assesses the potential of Fiber Bragg Grating (FBG)-based sensing for real-time needle (including catheter or tube) tracking during MR-guided HDR brachytherapy. METHODS: The proposed FBG-based sensing tracking approach involves a MR-compatible stylet composed of three optic fibers with nine sets of embedded FBG sensors each. When the stylet is inserted inside the lumen of the needle, the FBG sensing system can measure the needle's deflection...
June 2016: Medical Physics
S Seltzer
: The ICRU is currently finalizing a report on key data for radiation dosimetry. This multi-year review has resulted in a number of recommendations regarding "fundamental" data that are used in dosimetry related to radiation therapy. This educational session will explain the background for the ICRU committee's work, the content and conclusions of the report and the impact on outputs, including NIST primary standards, ADCL calibration coefficients and clinical reference dosimetry. Parameters and beam modalities potentially affected by this report include: The mean excitation energy, I, for graphite, air, and water, The average energy required to create an ion pair in dry air (commonly referred to as W/e), The uncertainty in the determination of air kerma in kV x-rays The absolute value of Co-60 and Cs-137 primary standards and the dissemination of calibration coefficients, The determination of air kerma strength for Ir-192 HDR brachytherapy sources Ion chamber kQ factors for linac MV beams Ion chamber kQ factors for proton beams...
June 2016: Medical Physics
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