http://scitation.aip.org/ Medical Physics, the international journal of medical physics research and practice, is the scientific journal of the American Association of Physicists in Medicine. http://link.aip.org/link/?MPH/39/1079/1&agg=rss Wei Liu, Xiaodong Zhang, Yupeng Li, and Radhe Mohan<br/> Purpose: Intensity modulated proton therapy (IMPT) is highly sensitive to range uncertainties and uncertainties caused by setup variation. The conventional inverse treatment planning of IMPT optimized based on the planning target volume (PTV) is not often sufficient to ensure robustness of treatmen ... [Med. Phys. 39, 1079 (2012)] published Fri Feb 3, 2012. http://link.aip.org/link/?MPH/39/1069/1&agg=rss Adam Richard Blais, Ernst Lederer, Michael Oliver, and Konrad Leszczynski<br/> Purpose: For certain clinical applications, rotational intensity modulated radiation therapy (R-IMRT) techniques such as volumetric modulated arc therapy (VMAT) are capable of improved target dose coverage and shorter delivery time when compared to static, step-and-shoot IMRT. The authors performed ... [Med. Phys. 39, 1069 (2012)] published Fri Feb 3, 2012. http://link.aip.org/link/?MPH/39/1046/1&agg=rss Jaewon Yang, Tokihiro Yamamoto, Byungchul Cho, Youngho Seo, and Paul J. Keall<br/> Purpose: Irregular breathing causes motion blurring artifacts in 4D PET images. Audiovisual (AV) biofeedback has been demonstrated to improve breathing regularity. To investigate the hypothesis that, compared with free breathing, motion blurring artifacts are reduced with AV biofeedback, the author ... [Med. Phys. 39, 1046 (2012)] published Fri Feb 3, 2012. http://link.aip.org/link/?MPH/39/1058/1&agg=rss Andrew Sampson, Yi Le, and Jeffrey F. Williamson<br/> Purpose: To demonstrate potential of correlated sampling Monte Carlo (CMC) simulation to improve the calculation efficiency for permanent seed brachytherapy (PSB) implants without loss of accuracy. Methods: CMC was implemented within an in-house MC code family (PTRAN) and used to compute 3D dose d ... [Med. Phys. 39, 1058 (2012)] published Fri Feb 3, 2012. http://link.aip.org/link/?MPH/39/1042/1&agg=rss Xiao Qiu-Jin, Wang Zhen, Kuang Ming-Xing, Wen Ping, Liu Pei et al.<br/> Purpose: The aim of the present study is to investigate an impedance change equation suited with the measurement of the impedance cardiograph (ICG). Methods: Based on a parallel impedance model and Ohm's law, an impedance change equation differed from Nyboer's equation is deduced. It is verified w ... [Med. Phys. 39, 1042 (2012)] published Fri Feb 3, 2012. http://link.aip.org/link/?MPH/39/1021/1&agg=rss Asa Holm, Torbjorn Larsson, and Asa Carlsson Tedgren<br/> Purpose: Dose plans generated with optimization models hitherto used in high-dose-rate (HDR) brachytherapy have shown a tendency to yield longer dwell times than manually optimized plans. Concern has been raised for the corresponding undesired hot spots, and various methods to mitigate these have b ... [Med. Phys. 39, 1021 (2012)] published Fri Feb 3, 2012. http://link.aip.org/link/?MPH/39/1029/1&agg=rss Ju-Chieh (Kevin) Cheng, Kooresh Shoghi, and Richard Laforest<br/> Purpose: Iterative reconstruction algorithms are becoming more commonly employed in positron emission tomography (PET) imaging; however, the quantitative accuracy of the reconstructed images still requires validation for various levels of contrast and counting statistics. Methods: The authors pres ... [Med. Phys. 39, 1029 (2012)] published Fri Feb 3, 2012. http://link.aip.org/link/?MPH/39/1016/1&agg=rss Nobuyuki Kanematsu, Taku Inaniwa, and Yusuke Koba<br/> Purpose: In treatment planning of charged-particle radiotherapy, patient heterogeneity is conventionally modeled as variable-density water converted from CT images to best reproduce the stopping power, which may lead to inaccuracies in the handling of multiple scattering and nuclear interactions. A ... [Med. Phys. 39, 1016 (2012)] published Thu Feb 2, 2012. http://link.aip.org/link/?MPH/39/1001/1&agg=rss Chan Hyeong Kim, Jin Hyung Park, Hee Seo, and Han Rim Lee<br/> Purpose: This paper describes a new gamma-ray imaging method, gamma electron vertex imaging (GEVI), which can be used for precise beam range verification in proton therapy. Methods: In GEVI imaging, the high-energy gammas from a source or nuclear interactions are first converted, by Compton scatte ... [Med. Phys. 39, 1001 (2012)] published Thu Feb 2, 2012. http://link.aip.org/link/?MPH/39/1006/1&agg=rss Jef Vandemeulebroucke, Olivier Bernard, Simon Rit, Jan Kybic, Patrick Clarysse et al.<br/> Purpose: Deformable registration generally relies on the assumption that the sought spatial transformation is smooth. Yet, breathing motion involves sliding of the lung with respect to the chest wall, causing a discontinuity in the motion field, and the smoothness assumption can lead to poor matchi ... [Med. Phys. 39, 1006 (2012)] published Thu Feb 2, 2012. http://link.aip.org/link/?MPH/39/988/1&agg=rss Yoshiki Kawata, Noboru Niki, Hironobu Ohmatsu, Masahiko Kusumoto, Takaaki Tsuchida et al.<br/> Purpose: Quantification of the CT appearance of non-small cell lung cancer (NSCLC) is of interest in a number of clinical and investigational applications. The purpose of this work is to present a quantitative five-category (alpha, beta, gamma, delta, and [eh]) classification method based on CT his ... [Med. Phys. 39, 988 (2012)] published Wed Feb 1, 2012. http://link.aip.org/link/?MPH/39/984/1&agg=rss B. Downton and S. Walker<br/> Purpose: To eliminate variation in electrometer calibration results caused by high humidity and suboptimal connectors on the standard capacitors and to implement hardware that prevents overloading of the input stage of electrometers during calibration. Methods: A humidity-controlled cabinet was in ... [Med. Phys. 39, 984 (2012)] published Wed Feb 1, 2012. http://link.aip.org/link/?MPH/39/976/1&agg=rss Nolan L. Gagne, Kara L. Leonard, Kathryn E. Huber, John E. Mignano, Jay S. Duker et al.<br/> Purpose: A method is introduced to examine the influence of implant duration T, radionuclide, and radiobiological parameters on the biologically effective dose (BED) throughout the entire volume of regions of interest for episcleral brachytherapy using available radionuclides. This method is employ ... [Med. Phys. 39, 976 (2012)] published Wed Feb 1, 2012. http://link.aip.org/link/?MPH/39/933/1&agg=rss Alison M. Pouch, Paul A. Yushkevich, Benjamin M. Jackson, Arminder S. Jassar, Mathieu Vergnat et al.<br/> Purpose: Precise 3D modeling of the mitral valve has the potential to improve our understanding of valve morphology, particularly in the setting of mitral regurgitation (MR). Toward this goal, the authors have developed a user-initialized algorithm for reconstructing valve geometry from transesopha ... [Med. Phys. 39, 933 (2012)] published Tue Jan 31, 2012. http://link.aip.org/link/?MPH/39/964/1&agg=rss Zhuoshi Wei, Jianhua Yao, Shijun Wang, Jiamin Liu, and Ronald M. Summers<br/> Purpose: Computed tomographic colonography (CTC) is a minimally invasive technique for colonic polyps and cancer screening. Teniae coli are three bands of longitudinal smooth muscle on the colon surface. Teniae coli are important anatomically meaningful landmarks on human colon. In this paper, the ... [Med. Phys. 39, 964 (2012)] published Tue Jan 31, 2012. http://link.aip.org/link/?MPH/39/951/1&agg=rss Sebastiaan Breedveld, Pascal R. M. Storchi, Peter W. J. Voet, and Ben J. M. Heijmen<br/> Purpose: To introduce iCycle, a novel algorithm for integrated, multicriterial optimization of beam angles, and intensity modulated radiotherapy (IMRT) profiles. Methods: A multicriterial plan optimization with iCycle is based on a prescription called wish-list, containing hard constraints and obj ... [Med. Phys. 39, 951 (2012)] published Tue Jan 31, 2012. http://link.aip.org/link/?MPH/39/922/1&agg=rss Hua Li, Camille Noel, Jose Garcia-Ramirez, Daniel Low, Jeffrey Bradley et al.<br/> Purpose: Phase-binning algorithms are commonly utilized in 4DCT image reconstruction for characterization of tumor or organ shape and respiration motion, but breathing irregularities occurring during 4DCT acquisition can cause considerable image distortions. Recently, amplitude-binning algorithms h ... [Med. Phys. 39, 922 (2012)] published Fri Jan 27, 2012. http://link.aip.org/link/?MPH/39/912/1&agg=rss Bijan Arjomandy, Ramesh Tailor, Li Zhao, and Slobodan Devic<br/> Purpose: One of the fundamental parameters used for dose calculation is percentage depth-dose, generally measured employing ionization chambers. There are situations where use of ion chambers for measuring depth-doses is difficult or problematic. In such cases, radiochromic film might be an alterna ... [Med. Phys. 39, 912 (2012)] published Thu Jan 26, 2012. http://link.aip.org/link/?MPH/39/906/1&agg=rss Adam M. Zysk, Jovan G. Brankov, Miles N. Wernick, and Mark A. Anastasio<br/> Purpose: Since the introduction of clinical x-ray phase-contrast mammography (PCM), a technique that exploits refractive-index variations to create edge enhancement at tissue boundaries, a number of optimization studies employing physical image-quality metrics have been performed. Ideally, task-bas ... [Med. Phys. 39, 906 (2012)] published Thu Jan 26, 2012. http://link.aip.org/link/?MPH/39/901/1&agg=rss Xinhua Li, Da Zhang, and Bob Liu<br/> Purpose: The aim of this study was to examine the variations of CT dose index (CTDI) efficiencies, epsilon(CTDI)=CTDI/CTDI, with bowtie filters and CT scanner types. Methods: This was an extension of our previous study [Li, Zhang, and Liu, Phys. Med. Biol. 56, 57895803 (2011)]. A validated Monte C ... [Med. Phys. 39, 901 (2012)] published Wed Jan 25, 2012. http://link.aip.org/link/?MPH/39/891/1&agg=rss Aman Anand, Narayan Sahoo, X. Ronald Zhu, Gabriel O. Sawakuchi, Falk Poenisch et al.<br/> Purpose: Planar integral spot dose (PISD) of proton pencil beam spots (PPBSs) is a required input parameter for beam modeling in some treatment planning systems used in proton therapy clinics. The measurement of PISD by using commercially available large area ionization chambers, like the PTW Bragg ... [Med. Phys. 39, 891 (2012)] published Wed Jan 25, 2012. http://link.aip.org/link/?MPH/39/874/1&agg=rss B. M. Oborn, P. E. Metcalfe, M. J. Butson, A. B. Rosenfeld, and P. J. Keall<br/> Purpose: In recent times, longitudinal field MRI-linac systems have been proposed for 6 MV MRI-guided radiotherapy (MRIgRT). The magnetic field is parallel with the beam axis and so will alter the transport properties of any electron contamination particles. The purpose of this work is to provide a ... [Med. Phys. 39, 874 (2012)] published Wed Jan 25, 2012. http://link.aip.org/link/?MPH/39/866/1&agg=rss I. Reiser, R. M. Nishikawa, M. L. Giger, J. M. Boone, K. K. Lindfors et al.<br/> Purpose: To develop an automated method to detect breast masses on dedicated breast CT (BCT) volumes and to conduct a preliminary evaluation of its performance. This method can be used in a computer-aided detection (CADe) system for noncontrast enhanced BCT. Methods: The database included patient ... [Med. Phys. 39, 866 (2012)] published Tue Jan 24, 2012. http://link.aip.org/link/?MPH/39/851/1&agg=rss Joseph Awad, Amir Owrangi, Lauren Villemaire, Elaine O'Riordan, Grace Parraga et al.<br/> Purpose: Manual segmentation of lung tumors is observer dependent and time-consuming but an important component of radiology and radiation oncology workflow. The objective of this study was to generate an automated lung tumor measurement tool for segmentation of pulmonary metastatic tumors from x-r ... [Med. Phys. 39, 851 (2012)] published Tue Jan 24, 2012. http://link.aip.org/link/?MPH/39/842/1&agg=rss Tawfik Giaddui, Yunfeng Cui, James Galvin, Wenzhou Chen, Yan Yu et al.<br/> Purpose: In this study, the relevant characteristics of the new Gafchromic XRQA2 film for its application in measuring kV cone beam computed tomography (CBCT) image doses were thoroughly investigated. Methods: The film was calibrated free in air to air kerma levels between 0 and 9 cGy using 120 kV ... [Med. Phys. 39, 842 (2012)] published Tue Jan 24, 2012. http://link.aip.org/link/?MPH/39/832/1&agg=rss C. M. Heirwegh, D. R. Chettle, and A. Pejovic-Milic<br/> Purpose: Energy dispersive x-ray fluorescence spectroscopy (XRS) measurements were performed on human cadaver index fingers to measure bone strontium content in the presence of intact overlying soft-tissue. This work assesses the feasibility of applying a normalization procedure including soft-tiss ... [Med. Phys. 39, 832 (2012)] published Tue Jan 24, 2012. http://link.aip.org/link/?MPH/39/825/1&agg=rss Rainer Grimmer, Rebecca Fahrig, Waldo Hinshaw, Hewei Gao, and Marc Kachelriess<br/> Purpose: X-ray CT measures the attenuation of polychromatic x-rays through an object. The rawdata acquired, which are the negative logarithm of the relative x-ray intensity behind the patient, must undergo water precorrection to linearize the measurement and to convert them into line integrals that ... [Med. Phys. 39, 825 (2012)] published Mon Jan 23, 2012. http://link.aip.org/link/?MPH/39/811/1&agg=rss Nicholas W. Marshall, Kim Lemmens, and Hilde Bosmans<br/> Purpose: Needle phosphor based computed radiography (CR) systems promise improved image quality compared to powder phosphor based CR units for x-ray screening mammography. This paper compares the imaging performance of needle CR cassettes, powder based CR cassettes and a well established amorphous ... [Med. Phys. 39, 811 (2012)] published Mon Jan 23, 2012. http://link.aip.org/link/?MPH/39/801/1&agg=rss Gang Wu, James G. Mainprize, and Martin J. Yaffe<br/> Purpose: Power spectral analysis in radiographic images is conventionally performed using a windowed overlapping averaging periodogram. This study describes an alternative approach using a multitaper technique and compares its performance with that of the standard method. This tool will be valuable ... [Med. Phys. 39, 801 (2012)] published Wed Jan 18, 2012. http://link.aip.org/link/?MPH/39/798/1&agg=rss Uwe Schneider, Jurgen Besserer, and Matthias Hartmann<br/> Purpose: Proton radiography and tomography were investigated since the early 1970s because of its low radiation dose, high density resolution, and ability to image directly proton stopping power. However, spatial resolution is still a limiting factor. In this note, preliminary results of the impact ... [Med. Phys. 39, 798 (2012)] published Wed Jan 18, 2012. http://link.aip.org/link/?MPH/39/788/1&agg=rss D. M. Santos, J. St. Aubin, B. G. Fallone, and S. Steciw<br/> Purpose: In our current linac-magnetic resonance (MR) design, a 6 MV in-line linac is placed along the central axis of the MR's magnet where the MR's fringe magnetic fields are parallel to the overall electron trajectories in the linac waveguide. Our previous study of this configuration comprising ... [Med. Phys. 39, 788 (2012)] published Wed Jan 18, 2012. http://link.aip.org/link/?MPH/39/742/1&agg=rss Qi Sun, Alexandra Groth, and Til Aach<br/> Purpose: Recently, image-based computational fluid dynamic (CFD) simulations have been proposed to investigate the local hemodynamics inside human cerebral aneurysms. It was suggested that the knowledge of the computed three-dimensional flow fields can be used to assist clinical risk assessment and ... [Med. Phys. 39, 742 (2012)] published Wed Jan 18, 2012. http://link.aip.org/link/?MPH/39/755/1&agg=rss Hidenobu Tachibana, Yukihiro Uchida, and Hisao Shiizuka<br/> Purpose: In this work, the authors determine the optimal template matching method and selection of pixel data for use in a system for monitoring patient intrafraction motion. Methods: The motion monitoring system is based on optical tracking of a marker block placed on the patient. The temporal re ... [Med. Phys. 39, 755 (2012)] published Wed Jan 18, 2012. http://link.aip.org/link/?MPH/39/777/1&agg=rss Chad Bircher and Yiping Shao<br/> Purpose: Positron emission tomography (PET) detectors that use a dual-ended-scintillator readout to measure depth-of-interaction (DOI) must have an accurate DOI function to provide the relationship between DOI and signal ratios to be used for detector calibration and recalibration. In a previous st ... [Med. Phys. 39, 777 (2012)] published Wed Jan 18, 2012. http://link.aip.org/link/?MPH/39/765/1&agg=rss Carolyn J. Niu, Warren D. Foltz, Michael Velec, Joanne L. Moseley, Adil Al-Mayah et al.<br/> Purpose: To propose a novel technique to experimentally validate deformable dose algorithms by measuring 3D dose distributions under the condition of deformation using deformable gel dosimeters produced by a novel gel fabrication method. Method: Five gel dosimeters, two rigid control gels and thre ... [Med. Phys. 39, 765 (2012)] published Wed Jan 18, 2012. http://link.aip.org/link/?MPH/39/721/1&agg=rss Nicholas Chng, Ingrid Spadinger, Rosey Rasoda, W. James Morris, and Septimiu Salcudean<br/> Purpose: In postimplant dosimetry for prostate brachytherapy, dose is commonly calculated using the TG-43 1D formalism, because seed orientations are difficult to determine from CT images, the current standard for the procedure. However, the orientation of stranded seeds soon after implantation is ... [Med. Phys. 39, 721 (2012)] published Thu Jan 12, 2012. http://link.aip.org/link/?MPH/39/706/1&agg=rss Stefania Pallotta, Livia Marrazzo, Marco Ceroti, Pierfrancesco Silli, and Marta Bucciolini<br/> Purpose: The aim of this study is to investigate the performance of Sentinel, a patient setup verification device based on a laser/camera system, when used on rigid-body phantoms. Methods: The Sentinel system consists of a scanner unit, containing the laser and the camera, and surface-matching reg ... [Med. Phys. 39, 706 (2012)] published Thu Jan 12, 2012. http://link.aip.org/link/?MPH/39/686/1&agg=rss David Craft, Dualta McQuaid, Jeremiah Wala, Wei Chen, Ehsan Salari et al.<br/> Purpose: To make the planning of volumetric modulated arc therapy (VMAT) faster and to explore the tradeoffs between planning objectives and delivery efficiency. Methods: A convex multicriteria dose optimization problem is solved for an angular grid of 180 equi-spaced beams. This allows the planne ... [Med. Phys. 39, 686 (2012)] published Thu Jan 12, 2012. http://link.aip.org/link/?MPH/39/697/1&agg=rss G. Asuni, D. W. Rickey, and B. M. C. McCurdy<br/> Purpose: The aim of this work is to characterize a new online dose verification device, COMPASS transmission detector array (IBA Dosimetry, Schwarzenbruck, Germany). The array is composed of 1600 cylindrical ionization chambers of 3.8 mm diameter, separated by 6.5 mm center-to-center spacing, in a ... [Med. Phys. 39, 697 (2012)] published Thu Jan 12, 2012. http://link.aip.org/link/?MPH/39/713/1&agg=rss Klaus Bratengeier, Markus Oechsner, and Mark Gainey<br/> Purpose: For fast adaptation of step and shoot intensity modulated radiotherapy (IMRT) plans, monitor units (MU)-preserving methods which modify only the segment shapes have been proposed in the literature. In this work, two such adaptation methods are applied to intensity modulated arc therapy (IM ... [Med. Phys. 39, 713 (2012)] published Thu Jan 12, 2012. http://link.aip.org/link/?MPH/39/658/1&agg=rss Martin Hupfer, Daniel Kolditz, Tristan Nowak, Fabian Eisa, Robert Brauweiler et al.<br/> Purpose: At present, no established methods exist for dosimetry in micro computed tomography (micro-CT). The purpose of this study was therefore to investigate practical concepts for both dosimetric scanner quality assurance and tissue dose assessment for micro-CT. Methods: The computed tomography ... [Med. Phys. 39, 658 (2012)] published Thu Jan 12, 2012. http://link.aip.org/link/?MPH/39/671/1&agg=rss Minoru Tajiri, Yuji Tokiya, and Kazuhiro Watanabe<br/> Purpose: The in-air output ratio (S) for a rectangular field is usually obtained using an equivalent square field formula. However, it is well-known that S obtained using an equivalent square field formula differs slightly from the measured S. Though several correction methods have been suggested f ... [Med. Phys. 39, 671 (2012)] published Thu Jan 12, 2012. http://link.aip.org/link/?MPH/39/676/1&agg=rss Hao Jing, Yongyi Yang, and Robert M. Nishikawa<br/> Purpose: The authors propose an image-retrieval based approach for case-adaptive classifier design in computer-aided diagnosis (CADx). The conventional approach in CADx is to first train a pattern-classifier based on a set of existing training samples and then apply this classifier to subsequent ne ... [Med. Phys. 39, 676 (2012)] published Thu Jan 12, 2012. http://link.aip.org/link/?MPH/39/643/1&agg=rss F. Sanchez, L. Moliner, C. Correcher, A. Gonzalez, A. Orero et al.<br/> Purpose: The authors have developed a small animal Positron emission tomography (PET) scanner based on monolithic LYSO crystals coupled to multi-anode photomultiplier tubes (MA-PMTs). In this study, the authors report on the design, calibration procedure, and performance evaluation of a PET system ... [Med. Phys. 39, 643 (2012)] published Thu Jan 12, 2012. http://link.aip.org/link/?MPH/39/654/1&agg=rss Hans Bornefalk<br/> Purpose: To determine the intrinsic dimensionality of linear attenuation coefficients (LACs) from XCOM for elements with low atomic number (Z = 120) at diagnostic x-ray energies (25120 keV). H, the hypothesis that the space of LACs is spanned by q bases, is tested for various q-values. Methods: Pr ... [Med. Phys. 39, 654 (2012)] published Thu Jan 12, 2012. http://link.aip.org/link/?MPH/39/732/1&agg=rss Jiahui Wang, James T. Dobbins, III, and Qiang Li<br/> Purpose: The purpose of this study was to develop an automated lung segmentation method for computerized detection of lung nodules in digital chest tomosynthesis. Methods: The authors collected 45 digital tomosynthesis scans and manually segmented reference lung regions in each scan to assess the ... [Med. Phys. 39, 732 (2012)] published Thu Jan 12, 2012. http://link.aip.org/link/?MPH/39/573/1&agg=rss Martin J. Murphy, Francisco J. Salguero, Jeffrey V. Siebers, David Staub, and Constantin Vaman<br/> Purpose: To develop a statistical sampling procedure for spatially-correlated uncertainties in deformable image registration and then use it to demonstrate their effect on daily dose mapping. Methods: Sequential daily CT studies are acquired to map anatomical variations prior to fractionated exter ... [Med. Phys. 39, 573 (2012)] published Wed Jan 11, 2012. http://link.aip.org/link/?MPH/39/569/1&agg=rss Indra J. Das, Christopher F. Njeh, and Colin G. Orton<br/> Abstract not available. [Med. Phys. 39, 569 (2012)] published Wed Jan 11, 2012. http://link.aip.org/link/?MPH/39/603/1&agg=rss Gengsheng L. Zeng<br/> Purpose: In order to eventually develop an analytical algorithm with noise characteristics of an iterative algorithm, this technical note develops a window function for the filtered backprojection (FBP) algorithm in tomography that behaves as an iterative Landweber algorithm. Methods: Based on the ... [Med. Phys. 39, 603 (2012)] published Wed Jan 11, 2012. http://link.aip.org/link/?MPH/39/636/1&agg=rss Thomas S. Pheiffer, Amber L. Simpson, Brian Lennon, Reid C. Thompson, and Michael I. Miga<br/> Purpose: Acquisition of laser range scans of an organ surface has the potential to efficiently provide measurements of geometric changes to soft tissue during a surgical procedure. A laser range scanner design is reported here which has been developed to drive intraoperative updates to conventional ... [Med. Phys. 39, 636 (2012)] published Wed Jan 11, 2012.