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Physica Medica: PM

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https://www.readbyqxmd.com/read/28625473/effect-of-dir-uncertainty-on-prostate-passive-scattering-proton-therapy-dose-accumulation
#1
Yoshitomo Abe, Noriyuki Kadoya, Kazuhiro Arai, Yoshiki Takayama, Takahiro Kato, Kanako Kimura, Takashi Ono, Tatsuya Nakamura, Hitoshi Wada, Yasuhiro Kikuchi, Keiichi Jingu
Deformable image registration (DIR) is important in dose accumulation. Currently, the impact of DIR-algorithm-associated uncertainties in proton therapy is unclear. Here, we quantify the effect of DIR uncertainties on prostate passive-scattering proton therapy (PSPT) dose accumulation. Ten patients with an intermediate risk for prostate cancer formerly treated by PSPT (PTV D95=78GyE) were studied. Dose distributions from all verification CT images (five images per patient) were warped and accumulated in the planning CT geometries with DIR...
June 15, 2017: Physica Medica: PM
https://www.readbyqxmd.com/read/28625472/3d-catheter-reconstruction-in-hdr-prostate-brachytherapy-for-pre-treatment-verification-using-a-flat-panel-detector
#2
Ryan L Smith, Annette Haworth, Vanessa Panettieri, Jeremy L Millar, Rick D Franich
PURPOSE: High dose rate prostate brachytherapy is a widely-practiced treatment, delivering large conformal doses in relatively few treatment fractions. Inter- and intra-fraction catheter displacements have been reported. Unrecognized displacement can have a significant impact on dosimetry. Knowledge of the implant geometry at the time of treatment is important for ensuring safe and effective treatment. In this work we demonstrate a method to reconstruct the catheter positions pre-treatment, using a 'shift' imaging technique, and perform registration with the treatment plan for verification relative to the prostate...
June 15, 2017: Physica Medica: PM
https://www.readbyqxmd.com/read/28624290/feasibility-of-reducing-differences-in-estimated-doses-in-nuclear-medicine-between-a-patient-specific-and-a-reference-phantom
#3
Alexandra Zvereva, Helmut Schlattl, Maria Zankl, Janine Becker, Nina Petoussi-Henss, Yeon Soo Yeom, Chan Hyeong Kim, Christoph Hoeschen, Katia Parodi
The feasibility of reducing the differences between patient-specific internal doses and doses estimated using reference phantoms was evaluated. Relatively simple adjustments to a polygon-surface ICRP adult male reference phantom were applied to fit selected individual dimensions using the software Rhinoceros®4.0. We tested this approach on two patient-specific phantoms: the biggest and the smallest phantoms from the Helmholtz Zentrum München library. These phantoms have unrelated anatomy and large differences in body-mass-index...
June 14, 2017: Physica Medica: PM
https://www.readbyqxmd.com/read/28623025/identification-of-elemental-weight-fraction-and-mass-density-of-humanoid-tissue-equivalent-materials-using-dual-energy-computed-tomography
#4
Kohei Shimomura, Fujio Araki, Yuki Kono, Yoshiyuki Asai, Takamichi Murakami, Tomoko Hyodo, Masahiko Okumura, Kenji Matsumoto, Hajime Monzen, Yasumasa Nishimura
The purpose of this study was to obtain the fraction by weight of the elemental composition and mass density of a humanoid tissue phantom that includes lung tissue, soft tissue, and bone tissue, by using dual energy computed tomography (DECT). The fraction by weight and the mass density for tissue-equivalent materials were calculated by means of a least-squares method with a linear attenuation coefficient, using monochromatic photon energies of 10-140keV, as obtained from DECT. The accuracy of calculated values for the fractions by weight of H (hydrogen), C (carbon), N (nitrogen), and O (oxygen) as verified by comparing the values with those that were analyzed using the combustion technique...
June 13, 2017: Physica Medica: PM
https://www.readbyqxmd.com/read/28619290/sparing-dysphagia-aspiration-related-structures-using-novel-hybrid-volumetric-modulated-arc-therapy
#5
Sitaraman BalajiSubramanian, Karunakaran Balaji, Moorthi Thirunavukarasu, Sumana Premkumar
PURPOSE: Studies using split field IMRT to spare dysphagia/aspiration related structures (DARS) have raised concern regarding dose uncertainty at matchline. This study explores the utility of hybrid VMAT in sparing the DARS and assesses matchline dose uncertainty in postoperative oral cavity cancer patients and compares it with VMAT. METHODS & MATERIALS: Ten postoperative oral cavity cancer patients were planned with h-VMAT and VMAT using the same planning CT dataset...
June 12, 2017: Physica Medica: PM
https://www.readbyqxmd.com/read/28619289/validation-of-a-method-for-dose-of-the-day-calculation-in-head-neck-tomotherapy-by-using-planning-ct-to-mvct-deformable-image-registration
#6
M Branchini, C Fiorino, I Dell'Oca, M L Belli, L Perna, N Di Muzio, R Calandrino, S Broggi
PURPOSE: The aim of this study was to test the feasibility and dosimetric accuracy of a method that employs planning CT-to-MVCT deformable image registration (DIR) for calculation of the daily dose for head and neck (HN) patients treated with Helical Tomotherapy (HT). METHODS: For each patient, the planning kVCT (CTplan) was deformably registered to the MVCT acquired at the 15th therapy session (MV15) with a B-Spline Free Form algorithm using Mattes mutual information (open-source software 3D Slicer), resulting in a deformed CT (CTdef)...
June 12, 2017: Physica Medica: PM
https://www.readbyqxmd.com/read/28606833/impact-of-physiological-breathing-motion-for-breast-cancer-radiotherapy-with-proton-beam-scanning-an-in-silico-study
#7
Anna M Flejmer, Behnaz Chehrazi, Dan Josefsson, Iuliana Toma-Dasu, Alexandru Dasu
This study investigates the impact of breathing motion on proton breast treatment plans. Twelve patients with CT datasets acquired during breath-hold-at-inhalation (BHI), breath-hold-at-exhalation (BHE) and in free-breathing (FB) were included in the study. Proton plans were designed for the left breast for BHI and subsequently recalculated for BHE or designed for FB and recalculated for the extreme breath-hold phases. The plans were compared from the point of view of their target coverage and doses to organs-at-risk...
June 9, 2017: Physica Medica: PM
https://www.readbyqxmd.com/read/28602688/quality-control-in-cone-beam-computed-tomography-cbct-efomp-estro-iaea-protocol-summary-report
#8
Hugo de Las Heras Gala, Alberto Torresin, Alexandru Dasu, Osvaldo Rampado, Harry Delis, Irene Hernández Girón, Chrysoula Theodorakou, Jonas Andersson, John Holroyd, Mats Nilsson, Sue Edyvean, Vesna Gershan, Lama Hadid-Beurrier, Christopher Hoog, Gregory Delpon, Ismael Sancho Kolster, Primož Peterlin, Julia Garayoa Roca, Paola Caprile, Costas Zervides
The aim of the guideline presented in this article is to unify the test parameters for image quality evaluation and radiation output in all types of cone-beam computed tomography (CBCT) systems. The applications of CBCT spread over dental and interventional radiology, guided surgery and radiotherapy. The chosen tests provide the means to objectively evaluate the performance and monitor the constancy of the imaging chain. Experience from all involved associations has been collected to achieve a consensus that is rigorous and helpful for the practice...
June 8, 2017: Physica Medica: PM
https://www.readbyqxmd.com/read/28601381/optimal-reconstruction-matrix-and-pet-image-filtration-for-point-spread-function-and-time-of-flight-reconstruction-a-phantom-study
#9
Jaroslav Ptáček, Pavel Karhan, Petr Fiala
INTRODUCTION: The aim of this study was to determine the optimal image matrix and half-width of the Gaussian filter after iterative reconstruction of the PET image with point-spread function (PSF) and time-of-flight (TOF) correction, based on measuring the recovery coefficient (RC) curves. The measured RC curves were compared to those from an older system which does not use PSF and TOF corrections. MATERIALS AND METHODS: The measurements were carried out on a NEMA IEC Body Phantom...
June 7, 2017: Physica Medica: PM
https://www.readbyqxmd.com/read/28599991/clinical-perspective-on-diagnostic-x-ray-examinations-of-pregnant-patients-what-to-take-into-account
#10
REVIEW
Peter Vock
Imaging during pregnancy has increased in frequency. Radiation protection is extremely important although tissue reactions of the conceptus, requiring a threshold dose of around 100mGy, are unlikely in the diagnostic use of X-rays and stochastic effects of cancerogenesis have a rather low risk (around 10(-4)/mGy for childhood cancer due to in utero exposure). This article will review the risk depending on dose and phase of pregnancy and the exposure by frequent examinations; it will then concentrate on the duties of an imaging department: screening for pregnancy, examination justification, planning and optimization, patient information, counseling, involving the patient in the decisions, and managing the situation of pregnant staff members...
June 6, 2017: Physica Medica: PM
https://www.readbyqxmd.com/read/28583292/design-of-experiments-in-medical-physics-application-to-the-aaa-beam-model-validation
#11
S Dufreneix, C Legrand, C Di Bartolo, M Bremaud, J Mesgouez, T Tiplica, D Autret
PURPOSE: The purpose of this study is to evaluate the usefulness of the design of experiments in the analysis of multiparametric problems related to the quality assurance in radiotherapy. The main motivation is to use this statistical method to optimize the quality assurance processes in the validation of beam models. METHOD: Considering the Varian Eclipse system, eight parameters with several levels were selected: energy, MLC, depth, X, Y1 and Y2 jaw dimensions, wedge and wedge jaw...
June 2, 2017: Physica Medica: PM
https://www.readbyqxmd.com/read/28583291/evaluation-of-a-commercial-model-based-iterative-reconstruction-algorithm-in-computed-tomography
#12
Nicoletta Paruccini, Raffaele Villa, Claudia Pasquali, Chiara Spadavecchia, Antonia Baglivi, Andrea Crespi
INTRODUCTION: Iterative reconstruction algorithms have been introduced in clinical practice to obtain dose reduction without compromising the diagnostic performance. PURPOSE: To investigate the commercial Model Based IMR algorithm by means of patient dose and image quality, with standard Fourier and alternative metrics. MATERIALS AND METHODS: A Catphan phantom, a commercial density phantom and a cylindrical water filled phantom were scanned both varying CTDIvol and reconstruction thickness...
June 2, 2017: Physica Medica: PM
https://www.readbyqxmd.com/read/28576582/visualization-of-air-and-metal-inhomogeneities-in-phantoms-irradiated-by-carbon-ion-beams-using-prompt-secondary-ions
#13
T Gaa, M Reinhart, B Hartmann, J Jakubek, P Soukup, O Jäkel, M Martišíková
PURPOSE: Non-invasive methods for monitoring of the therapeutic ion beam extension in the patient are desired in order to handle deteriorations of the dose distribution related to changes of the patient geometry. In carbon ion radiotherapy, secondary light ions represent one of potential sources of information about the dose distribution in the irradiated target. The capability to detect range-changing inhomogeneities inside of an otherwise homogeneous phantom, based on single track measurements, is addressed in this paper...
May 30, 2017: Physica Medica: PM
https://www.readbyqxmd.com/read/28576581/in-vivo-dosimetry-for-lung-radiotherapy-including-sbrt
#14
REVIEW
Boyd M C McCurdy, Peter M McCowan
SBRT for lung cancer is being rapidly adopted as a treatment option in modern radiotherapy centres. This treatment is one of the most complex in common clinical use, requiring significant expertise and resources. It delivers a high dose per fraction (typically ∼6-30Gy/fraction) over few fractions. The complexity and high dose delivered in only a few fractions make powerful arguments for the application of in vivo dosimetry methods for these treatments to enhance patient safety. In vivo dosimetry is a group of techniques with a common objective - to estimate the dose delivered to the patient through a direct measurement of the treatment beam(s)...
May 30, 2017: Physica Medica: PM
https://www.readbyqxmd.com/read/28566240/frontiers-in-planning-optimization-for-lung-sbrt
#15
Francesca Romana Giglioli, Stefania Clemente, Marco Esposito, Christian Fiandra, Carmelo Marino, Serenella Russo, Lidia Strigari, Elena Villaggi, Michele Stasi, Pietro Mancosu
Emerging data are showing the safety and the efficacy of Stereotactic Body Radiation therapy (SBRT) in lung cancer management. In this context, the very high doses delivered to the Planning Target Volume, make the planning phase essential for achieving high dose levels conformed to the shape of the target in order to have a good prognosis for tumor control and to avoid an overdose in relevant healthy adjacent tissue. In this non-systematic review we analyzed the technological and the physics aspects of SBRT planning for lung cancer...
May 26, 2017: Physica Medica: PM
https://www.readbyqxmd.com/read/28551298/digital-imaging-and-communications-in-medicine-dicom-information-conversion-procedure-for-suv-calculation-of-pet-scanners-with-different-dicom-header-information
#16
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
https://www.readbyqxmd.com/read/28526235/zero-echo-time-mri-only-treatment-planning-for-radiation-therapy-of-brain-tumors-after-resection
#17
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
https://www.readbyqxmd.com/read/28511776/radiation-induced-cancer-risk-predictions-in-proton-and-heavy-ion-radiotherapy
#18
REVIEW
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
https://www.readbyqxmd.com/read/28506649/dose-optimization-in-cardiac-ct
#19
REVIEW
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
https://www.readbyqxmd.com/read/28506453/challenges-of-dosimetry-of-ultra-short-pulsed-very-high-energy-electron-beams
#20
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
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