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Physica Medica: PM

Han-Back Shin, Heesoon Sheen, Ho-Young Lee, Jihoon Kang, Do-Kun Yoon, Tae Suk Suh
PURPOSE: In nuclear medicine, the standardized uptake value (SUV) obtained using positron emission tomography with 2-deoxy-2-fluoro-D-glucose (FDG-PET) is widely used as a semi-quantitative diagnosis factor. We found that the header file of the Philips Allegro PET scanner using the Digital Imaging and Communications in Medicine (DICOM) standard was stored differently than with other scanners. Thus, the purpose of this study was to develop a DICOM header information conversion program to ensure compatibility between Allegro and other equipment...
May 24, 2017: Physica Medica: PM
C Boydev, B Demol, D Pasquier, H Saint-Jalmes, G Delpon, N Reynaert
Using magnetic resonance imaging (MRI) as the sole imaging modality for patient modeling in radiation therapy (RT) is a challenging task due to the need to derive electron density information from MRI and construct a so-called pseudo-computed tomography (pCT) image. We have previously published a new method to derive pCT images from head T1-weighted (T1-w) MR images using a single-atlas propagation scheme followed by a post hoc correction of the mapped CT numbers using local intensity information. The purpose of this study was to investigate the performance of our method with head zero echo time (ZTE) MR images...
May 16, 2017: Physica Medica: PM
Camilla Hanquist Stokkevåg, Uwe Schneider, Ludvig Paul Muren, Wayne Newhauser
No abstract text is available yet for this article.
May 13, 2017: Physica Medica: PM
Sandeep Hedgire, Brian Ghoshhajra, Mannudeep Kalra
Rapid progress in the field of Cardiac CT is fostered by the advances in CT scanner technology as well as multiple clinical trials demonstrating its role in coronary artery disease and other indications like congenital heart disease, pulmonary vein assessment and pre transcatheter aortic valve replacement. The cardiovascular imager today is responsible for delivering diagnostic image quality while striking a balance with optimized radiation dose. Radiation dose is the result of multiple scanner and patient related factors...
May 12, 2017: Physica Medica: PM
Anna Subiel, Vadim Moskvin, Gregor H Welsh, Silvia Cipiccia, David Reboredo, Colleen DesRosiers, Dino A Jaroszynski
Very high energy electrons (VHEE) in the range from 100 to 250MeV have the potential of becoming an alternative modality in radiotherapy because of their improved dosimetric properties compared with 6-20MV photons generated by clinical linear accelerators (LINACs). VHEE beams have characteristics unlike any other beams currently used for radiotherapy: femtosecond to picosecond duration electron bunches, which leads to very high dose per pulse, and energies that exceed that currently used in clinical applications...
May 11, 2017: Physica Medica: PM
Paolo Zanotti-Fregonara, Elif Hindie
The number of nuclear medicine examinations performed worldwide has been steadily increasing over the last few years. By consequence, an ever increasing number of pregnant women are likely to be exposed to radioisotopes. The range of doses encountered in nuclear medicine practice is well below the threshold for deterministic effects, such as embryonic death, birth defects or mental retardation. According to the linear no-threshold hypothesis, however, stochastic effects (e.g. an increased risk of cancer) remain possible even at this dose range...
May 11, 2017: Physica Medica: PM
J Cortes-Rodicio, G Sanchez-Merino, M A Garcia-Fidalgo, I Tobalina-Larrea
PURPOSE: To design, build and test a stereotactic device that allows PET image-guided biopsies to be performed. METHODS: An initial prototype consisting of four main pieces, one of which contains radioactive markers to make it visible in the PET images, was built using a 3D printer. Once the device is mounted, a spherical coordinate system is built with the entrance needle point in the skin as the origin of coordinates. Two in-house software programs, namely getCoord...
May 10, 2017: Physica Medica: PM
M Carrara, A Romanyukha, C Tenconi, D Mazzeo, A Cerrotta, M Borroni, D Cutajar, M Petasecca, M Lerch, J Bucci, A Richetti, S Presilla, C Fallai, G Gambarini, E Pignoli, A Rosenfeld
PURPOSE: Three MOSkins dosimeters were assembled over a rectal probe and used to perform in vivo dosimetry during HDR brachytherapy treatments of vaginal cancer. The purpose of this study was to verify the applicability of the developed tool to evaluate discrepancies between planned and measured doses to the rectal wall. MATERIALS AND METHODS: MOSkin dosimeters from the Centre for Medical Radiation Physics are particularly suitable for brachytherapy procedures for their ability to be easily incorporated into treatment instrumentation...
May 9, 2017: Physica Medica: PM
Jorge Isidoro, Paulo Gil, Gracinda Costa, João Pedroso de Lima, Caseiro Alves, Nuno C Ferreira
PURPOSE: The aim of this study is to compare two routine protocols at our institution, CTPA and V/P-SPECT, in terms of radiation dose to the most exposed organs (lungs and breast) and to the embryo/fetus in the case of pregnant patients. METHODS: At our institution, the CTPA protocol includes a contrast enhanced CT (scan parameters: 100kVp, 700mA, 0.5s/rot, pitch 0.984) and in some cases a non-contrast enhanced CT acquisition (120kVp, 400mA, 0.5s/rot, pitch 1.375)...
May 6, 2017: Physica Medica: PM
Yanka Baneva, Kristina Bliznakova, Lesley Cockmartin, Stoyko Marinov, Ivan Buliev, Giovanni Mettivier, Hilde Bosmans, Paolo Russo, Nicholas Marshall, Zhivko Bliznakov
INTRODUCTION: In X-ray imaging, test objects reproducing breast anatomy characteristics are realized to optimize issues such as image processing or reconstruction, lesion detection performance, image quality and radiation induced detriment. Recently, a physical phantom with a structured background has been introduced for both 2D mammography and breast tomosynthesis. A software version of this phantom and a few related versions are now available and a comparison between these 3D software phantoms and the physical phantom will be presented...
May 5, 2017: Physica Medica: PM
F Simeonov, N Palov, D Ivanova, D Kostova-Lefterova, E Georgiev, A Zagorska, R Madzharova, J Vassileva
In the period 2013-2016 the National Centre of Radiobiology and Radiation Protection (NCRRP) at the Ministry of Health of Bulgaria has developed a web based platform for performing national patient dose surveys and establishing Diagnostic Reference Levels (DRLs). It is accessible via internet browser, allowing the users to submit data remotely. Electronic questionnaires, specific for radiography, fluoroscopy, image guided interventional procedures, mammography and CT, were provided. Short and clear manuals were added to guide users and minimise human errors...
May 4, 2017: Physica Medica: PM
Bae Chu, Daniel Miodownik, Matthew J Williamson, Yiming Gao, Jean St Germain, Lawrence T Dauer
PURPOSE: Most radiation protection programs, regulations and guidance apply specific restrictions to the occupational exposure of pregnant workers. The aim of this study was to compile data from the declared pregnant woman (DPW) radiation protection program over more than 5years at a large, high-volume, comprehensive oncology academic/medical institution and to evaluate for effectiveness against existing regulations and guidance. METHODS: A retrospective review was performed of the data collected as part of the DPW radiation protection program from January 2010 through May 2016, including the number of declared pregnancies, worker category, personal and fetal dosimetry monitoring measurements, workplace modifications, as well as the monthly and total recorded badge results during the entire pregnancy...
April 27, 2017: Physica Medica: PM
Vasiliki Peppa, Eleftherios P Pappas, Pantelis Karaiskos, Panagiotis Papagiannis
PURPOSE: To investigate the biological significance of introducing time-resolved dose rate distributions (TR-DRD) in brachytherapy. MATERIALS AND METHODS: The treatment plan of a head and neck patient treated with pulsed-dose-rate (PDR) brachytherapy was considered. The TR-DRD was calculated on the basis of a Monte Carlo generated single source dose rate matrix taking into account the dose rate per source dwell position. Biologically Effective Dose (BED) was obtained considering either the mean dose rate per pulse (analytical method) or the TR-DRD (numerical method)...
April 27, 2017: Physica Medica: PM
Massimiliano Pacilio, Bartolomeo Cassano, Rosanna Pellegrini, Elisabetta Di Castro, Alessandra Zorz, Giuseppe De Vincentis, Guido Ventroni, Lucio Mango, Stefano Giancola, Mahila Ferrari, Marta Cremonesi, Claudia Bianchi, Giorgio Virotta, Claudia Carbonini, Patrizia Cesana, Cristian Fulcheri, Valentina Reggioli, Alessandra Ricci, Edoardo Trevisiol, Silvia Anglesio, Roberto Pani
PURPOSE: The aim was to calibrate gamma cameras in the framework of the Italian multicentre study for lesion dosimetry in (223)Ra therapy of bone metastases. Equipments of several manufacturers and different models were used. METHODS: Eleven gamma cameras (3/8- and 5/8-inch crystal) were used, acquiring planar static images with double-peak (82 and 154keV, 20% wide) and MEGP collimator. The sensitivity was measured in air, varying source-detector distance and source size...
April 27, 2017: Physica Medica: PM
Michael G Stabin
This article discusses issues regarding administration of radiopharmaceuticals to pregnant women. Standardized dose estimates and possible biological effects on the unborn child are presented. Current and future mathematical models (phantoms) are discussed. Standardized dose estimates for pregnant women at several stages of gestation based on the current generation of phantoms are given. Issues related to administration of radioiodines, particularly (131)I-NaI, are presented. Iodine concentrates in the fetal thyroid and therefore can give very high doses, even resulting in complete destruction of the fetal thyroid...
April 25, 2017: Physica Medica: PM
S Beilla, T Younes, L Vieillevigne, M Bardies, X Franceries, L Simon
PURPOSE: Commercial algorithms used in Radiotherapy include approximations that are generally acceptable. However their limits can be seen when confronted with small fields and low-density media. These conditions exist during the treatment of lung cancers with Stereotactic Body Radiation Therapy (SBRT) achieved with the "Deep Inspiration Breath Hold" (DIBH) technique. A Monte Carlo (MC) model of a linear accelerator was used to assess the performance of two algorithms (Varian Acuros and AAA) in these conditions...
April 24, 2017: Physica Medica: PM
F De Rose, D Franceschini, G Reggiori, A Stravato, P Navarria, A M Ascolese, S Tomatis, P Mancosu, M Scorsetti
Lung stereotactic body radiotherapy (SBRT) is an accurate and precise technique to treat lung tumors with high 'ablative' doses. Given the encouraging data in terms of local control and toxicity profile, SBRT has currently become a treatment option for both early stage lung cancer and lung oligometastatic disease in patients who are medically inoperable or refuse surgical resection. Dose-adapted fractionation schedules and ongoing prospective trials should provide further evidence of SBRT safety trying to reduce toxicities and complications...
April 19, 2017: Physica Medica: PM
E Jiménez-Ortega, A Ureba, A Vargas, J A Baeza, A Wals-Zurita, F J García-Gómez, A R Barbeiro, A Leal
PURPOSE: To develop a new optimization algorithm to carry out true dose painting by numbers (DPBN) planning based on full Monte Carlo (MC) calculation. METHODS: Four configurations with different clustering of the voxel values from PET data were proposed. An optimization method at the voxel level under Lineal Programming (LP) formulation was used for an inverse planning and implemented in CARMEN, an in-house Monte Carlo treatment planning system. RESULTS: Beamlet solutions fulfilled the objectives and did not show significant differences between the different configurations...
April 12, 2017: Physica Medica: PM
H Delis, K Christaki, B Healy, G Loreti, G L Poli, P Toroi, A Meghzifene
Quality control (QC), according to ISO definitions, represents the most basic level of quality. It is considered to be the snapshot of the performance or the characteristics of a product or service, in order to verify that it complies with the requirements. Although it is usually believed that "the role of medical physicists in Diagnostic Radiology is QC", this, not only limits the contribution of medical physicists, but is also no longer adequate to meet the needs of Diagnostic Radiology in terms of Quality...
April 12, 2017: Physica Medica: PM
Á Perales, M A Cortés-Giraldo, H Miras, R Arráns, M I Gallardo
PURPOSE: We have developed an inhouse algorithm for the multileaf collimator (MLC) geometry model construction with an appropriate accuracy for dosimetric tests. Our purpose is to build a complex type of MLC and analyze the influence of the modeling parameters on the dose calculation. METHODS: Using radiochromic films as detector the following tests were done: (I) Density test field: to compare measured and calculated dose distributions in order to determine the tungsten alloy physical density value...
April 7, 2017: Physica Medica: PM
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