abstract：PURPOSE:To introduce a pair of accelerated non-Cartesian acquisition principles that when combined, exploit the periodicity of k-space acquisition, and thereby enable acquisition of high-temporal cine Cardiac Magnetic Resonance (CMR). METHODS:The mathematical formulation of a noniterative, undersampled non-Cartesian c...

journal_title：Medical physics

authors： Kawaji K,Patel MB,Cantrell CG,Tanaka A,Marino M,Tamura S,Wang H,Wang Y,Carroll TJ,Ota T,Patel AR

更新日期：2017-07-01 00:00:00

abstract：PURPOSE:The use of X-ray imaging in radiation therapy can give a substantial dose to the patient. A Cobalt machine combined with an magnetic resonance imaging (MRI) was recently introduced to clinical work. One positive aspect of using non-ionizing imaging devices is the reduction of the patient exposure. The purpose o...

journal_title：Medical physics

authors： Hauri P,Hälg RA,Schneider U

更新日期：2017-07-01 00:00:00

abstract：PURPOSE:In CT-guided liver tumor ablation interventions, registration of a preoperative contrast-enhanced CT image to the intraoperative CT image is hypothesized to improve guidance. This is a highly challenging registration task due to differences in patient poses and large deformations, and therefore high registratio...

journal_title：Medical physics

authors： Gunay G,Luu MH,Moelker A,van Walsum T,Klein S

更新日期：2017-07-01 00:00:00

abstract：PURPOSE:Coronary x-ray computed tomography angiography (CCTA) is used to non-invasively assess coronary artery geometry and has, combined with computational modeling, demonstrated the potential to identify physiologically significant lesions. These measurements require robust and accurate coronary imaging and delineati...

journal_title：Medical physics

authors： Contijoch F,Stayman JW,McVeigh ER

更新日期：2017-07-01 00:00:00

abstract：PURPOSE:In 3D gradient echo magnetic resonance imaging (MRI), strong field gradients B0macro are visually observed at air/tissue interfaces. At low spatial resolution in particular, the respective field gradients lead to an apparent increase in intravoxel dephasing, and subsequently, to signal loss or inaccurate R2* es...

journal_title：Medical physics

authors： Fatnassi C,Boucenna R,Zaidi H

更新日期：2017-07-01 00:00:00

abstract：PURPOSE:To examine the response properties of cylindrical cavity ionization chambers (ICs) in the depth-ionization buildup region so as to obtain a robust chamber-signal - based method for definitive water surface identification, hence absolute ionization chamber depth localization. METHOD & MATERIALS:An analytical mo...

journal_title：Medical physics

authors： Siebers JV,Ververs JD,Tessier F

更新日期：2017-07-01 00:00:00

abstract：PURPOSE:Avoiding measurement variability from 18 F phantom preparation by using 68 Ge/68 Ga phantoms for the determination of 18 F recovery curves (RC) in clinical quality assurance measurements and for PET/CT site qualification in multicentre clinical trials. METHODS:RCs were obtained from PET/CT measurements of seve...

journal_title：Medical physics

authors： Prenosil GA,Hentschel M,Fürstner M,Krause T,Weitzel T,Klaeser B

更新日期：2017-07-01 00:00:00

abstract：BACKGROUND AND PURPOSE:Differential baseline shifts between primary tumor and involved lymph nodes in locally advanced lung cancer patients compromise the accuracy of radiotherapy. The purpose of this study was to evaluate the performance of an average anatomy model (AAM) derived from repeat imaging and deformable regi...

journal_title：Medical physics

authors： Abdoli M,Van Kranen SR,Stankovic U,Rossi MMG,Belderbos JSA,Sonke JJ

更新日期：2017-07-01 00:00:00

abstract：PURPOSE:To investigate the acoustic radiation due to eddy current-cryostat interactions and perform a qualitative analysis on noise reduction methods. METHODS:In order to evaluate the sound pressure level (SPL) of the eddy current induced warm bore wall vibration, a Finite Element (FE) model was created to simulate th...

journal_title：Medical physics

authors： Wang Y,Liu F,Zhou X,Li Y,Crozier S

更新日期：2017-06-01 00:00:00

abstract：PURPOSE:Respiratory motion compensation in PET/CT and PET/MRI is essential as motion is a source of image degradation (motion blur, attenuation artifacts). In previous work, we developed a direct method for joint image reconstruction/motion estimation (JRM) for attenuation-corrected (AC) respiratory-gated PET, which us...

journal_title：Medical physics

authors： Bousse A,Manber R,Holman BF,Atkinson D,Arridge S,Ourselin S,Hutton BF,Thielemans K

更新日期：2017-06-01 00:00:00

abstract：PURPOSE:Modern CT systems adjust X-ray flux accommodating for patient size to achieve certain image noise values. The effectiveness of this adaptation is an important aspect of CT performance and should ideally be characterized in the context of real patient cases. The objective of this study was to characterize CT per...

journal_title：Medical physics

authors： Ria F,Wilson JM,Zhang Y,Samei E

更新日期：2017-06-01 00:00:00

abstract：PURPOSE:We report on the development of the open-source cross-platform radiation treatment planning toolkit matRad and its comparison against validated treatment planning systems. The toolkit enables three-dimensional intensity-modulated radiation therapy treatment planning for photons, scanned protons and scanned carb...

journal_title：Medical physics

authors： Wieser HP,Cisternas E,Wahl N,Ulrich S,Stadler A,Mescher H,Müller LR,Klinge T,Gabrys H,Burigo L,Mairani A,Ecker S,Ackermann B,Ellerbrock M,Parodi K,Jäkel O,Bangert M

更新日期：2017-06-01 00:00:00

abstract：PURPOSE:The aim of this study was to evaluate a surrogate-driven motion model based on four-dimensional computed tomography that is able to predict CT volumes corresponding to arbitrary respiratory phases. Furthermore, the comparison of three different driving surrogates is examined and the feasibility of using the mod...

journal_title：Medical physics

authors： Wölfelschneider J,Seregni M,Fassi A,Ziegler M,Baroni G,Fietkau R,Riboldi M,Bert C

更新日期：2017-06-01 00:00:00

abstract：PURPOSE:To formulate convex planning objectives of treatment plan multicriteria optimization with explicit relationships to the dose-volume histogram (DVH) statistics used in plan quality evaluation. METHODS:Conventional planning objectives are designed to minimize the violation of DVH statistics thresholds using pena...

journal_title：Medical physics

authors： Engberg L,Forsgren A,Eriksson K,Hårdemark B

更新日期：2017-06-01 00:00:00

abstract：PURPOSE:It is very important for calculation of clinical indices and diagnosis to detect thyroid nodules from ultrasound images. However, this task is a challenge mainly due to heterogeneous thyroid nodules with distinct components are similar to background in ultrasound images. In this study, we employ cascade deep co...

journal_title：Medical physics

authors： Ma J,Wu F,Jiang T,Zhu J,Kong D

更新日期：2017-05-01 00:00:00

abstract：PURPOSE:A high resolution, water equivalent, optical and passive x-ray dosimeter has been constructed using plastic scintillator and optical fiber. This dosimeter has a peak edge-on spatial resolution of 100 μm in one dimension, with a 10 μm resolution dosimeter under investigation. The dosimeter design has a potential...

journal_title：Medical physics

authors： Archer J,Li E,Petasecca M,Lerch M,Rosenfeld A,Carolan M

更新日期：2017-05-01 00:00:00

abstract：PURPOSE:We investigated the feasibility of using simpler methods than manual whole-organ volume-of-interest (VOI) definition to estimate the organ activity concentration in single photon emission computed tomography (SPECT) in cases where the activity in the organ can be assumed to be uniformly distributed on the scale...

journal_title：Medical physics

authors： Vicente EM,Lodge MA,Rowe SP,Wahl RL,Frey EC

更新日期：2017-05-01 00:00:00

abstract：PURPOSE:Bilateral filters have been substantially exploited in numerous magnetic resonance (MR) image restoration applications for decades. Due to the deficiency of theoretical basis on the filter parameter setting, empirical manipulation with fixed values and noise variance-related adjustments has generally been emplo...

journal_title：Medical physics

authors： Chang HH,Chang YN

更新日期：2017-04-01 00:00:00

abstract：PURPOSE:Most radiation therapy optimization problems can be formulated as an unconstrained problem and solved efficiently by quasi-Newton methods such as the Limited-memory Broyden-Fletcher-Goldfarb-Shanno (L-BFGS) algorithm. However, several next generation planning techniques such as total variation regularization- b...

journal_title：Medical physics

authors： Liu X,Pelizzari C,Belcher AH,Grelewicz Z,Wiersma RD

更新日期：2017-04-01 00:00:00

abstract：:In a recent paper of Miller et al. (Med. Phys. 43(5), 2141-2152 (2016), the voltage dependence polarity effect of microionization chambers was studied. It was identified that polarity effect arises from the difference in electric potential between the collecting electrode and the guard electrode, which in turn deforms...

journal_title：Medical physics

authors： Brivio D,Sajo E,Zygmanski P

更新日期：2017-03-01 00:00:00

abstract：PURPOSE/OBJECTIVE:Couch and MLC tracking are two novel techniques to mitigate intrafractional tumor motion on a conventional linear accelerator, but both techniques still have residual dosimetric errors. Here, we first propose and experimentally validate a software tool to simulate couch and MLC tracking, and then use ...

journal_title：Medical physics

authors： Toftegaard J,Hansen R,Ravkilde T,Macek K,Poulsen PR

更新日期：2017-03-01 00:00:00

abstract：PURPOSE:This study introduces a new hybrid ZTE/Dixon MR-based attenuation correction (MRAC) method including bone density estimation for PET/MRI and quantifies the effects of bone attenuation on metastatic lesion uptake in the pelvis. METHODS:Six patients with pelvic lesions were scanned using fluorodeoxyglucose (18F-...

journal_title：Medical physics

authors： Leynes AP,Yang J,Shanbhag DD,Kaushik SS,Seo Y,Hope TA,Wiesinger F,Larson PE

更新日期：2017-03-01 00:00:00

abstract：PURPOSE:It is estimated that 7% of women in the western world will develop palpable breast cysts in their lifetime. Even though cysts have been correlated with risk of developing breast cancer, many of them are benign and do not require follow-up. We develop a method to discriminate benign solitary cysts from malignant...

journal_title：Medical physics

authors： Kooi T,van Ginneken B,Karssemeijer N,den Heeten A

更新日期：2017-03-01 00:00:00

abstract：PURPOSE:The aim of this study was to assess the suitability of Gafchromic EBT3 films for reference dose measurements in the beam of a prototype high dose-per-pulse linear accelerator (linac), capable of delivering electron beams with a mean dose-rate (Ḋm ) ranging from 0.07 to 3000 Gy/s and a dose-rate in pulse (Ḋp ) o...

journal_title：Medical physics

authors： Jaccard M,Petersson K,Buchillier T,Germond JF,Durán MT,Vozenin MC,Bourhis J,Bochud FO,Bailat C

更新日期：2017-02-01 00:00:00

abstract：PURPOSE:To investigate the accuracy of output factor measurements using a commercial (Exradin W1, SI) and a prototype, "in-house" developed, plastic scintillation dosimeter (PSD) in small photon fields. METHODS:Repetitive detector-specific output factor OFdet measurements were performed in water (parallel to the CAX) ...

journal_title：Medical physics

authors： Papaconstadopoulos P,Archambault L,Seuntjens J

更新日期：2017-02-01 00:00:00

abstract：PURPOSE:Couch-mounted cone-beam computed tomography (CBCT) imaging devices with independently rotatable x-ray source and flat-panel detector arms for acquisitions of arbitrary regions of interest (ROI) have recently been introduced in image-guided radiotherapy (IGRT). This work analyzes mechanical limitations and gravi...

journal_title：Medical physics

authors： Keuschnigg P,Kellner D,Fritscher K,Zechner A,Mayer U,Huber P,Sedlmayer F,Deutschmann H,Steininger P

更新日期：2017-01-01 00:00:00

abstract：PURPOSE:The hematopoietically active tissues of skeletal bone marrow are a prime target for computational dosimetry given potential risks of leukemia and, at higher dose levels, acute marrow toxicity. The complex three-dimensional geometry of trabecular spongiosa, however, complicates schema for dose assessment in such...

journal_title：Medical physics

authors： Geyer AM,Schwarz BC,Hobbs RF,Sgouros G,Bolch WE

更新日期：2017-01-01 00:00:00

abstract：PURPOSE:In the nuclear medicine department, the activity of radiopharmaceuticals is measured using dose calibrators (DCs) prior to patient injection. The DC consists of an ionization chamber that measures current generated by ionizing radiation (emitted from the radiotracer). In order to obtain an activity reading, the...

journal_title：Medical physics

authors： Esquinas PL,Tanguay J,Gonzalez M,Vuckovic M,Rodríguez-Rodríguez C,Häfeli UO,Celler A

更新日期：2016-12-01 00:00:00

abstract：PURPOSE:Stringent quality assurance is required in MRI breast screening to ensure that different scanners and imaging protocols reach similar diagnostic performance. The authors propose a methodology, based on power spectrum analysis (PSA), to evaluate spatial resolution in clinical images. To demonstrate this approach...

journal_title：Medical physics

authors： Borri M,Scurr ED,Richardson C,Usher M,Leach MO,Schmidt MA

更新日期：2016-12-01 00:00:00

abstract：PURPOSE:The first main aim of this study was to illustrate the absorbed dose rate distribution from 177Lu in sections of xenografted prostate cancer (PCa) tumors using high resolution digital autoradiography (DAR) and compare it with hypothetical identical radioactivity distributions of 90Y or 7 MeV alpha-particles. Th...

journal_title：Medical physics

authors： Timmermand OV,Nilsson J,Strand SE,Elgqvist J

更新日期：2016-12-01 00:00:00

abstract：PURPOSE:The previously described 2D standardized vessel-wall-plus-plaque thickness (VWT) maps constructed from 3D ultrasound vessel wall measurements using an arc-length (AL) scaling approach adjusted the geometric variability of carotid arteries and has allowed for the comparisons of VWT distributions in longitudinal ...

journal_title：Medical physics

authors： Chen Y,Chiu B

更新日期：2016-12-01 00:00:00

abstract：PURPOSE:A detailed analysis of 2728 intensity modulated proton therapy (IMPT) fields that were clinically delivered to patients between 2007 and 2013 at Paul Scherrer Institute (PSI) was performed. The aim of this study was to analyze the results of patient specific dosimetric verifications and to assess possible corre...

journal_title：Medical physics

authors： Trnková P,Bolsi A,Albertini F,Weber DC,Lomax AJ

更新日期：2016-11-01 00:00:00

abstract：PURPOSE:The aim of this work is to search for new metrics that could give more reliable acceptance/rejection criteria on the IMRT verification process and to offer solutions to the discrepancies found among different conventional metrics. Therefore, besides conventional metrics, new ones are proposed and evaluated with...

journal_title：Medical physics

authors： Garcia-Romero A,Hernandez-Vitoria A,Millan-Cebrian E,Alba-Escorihuela V,Serrano-Zabaleta S,Ortega-Pardina P

更新日期：2016-11-01 00:00:00

abstract：PURPOSE:Having been overlooked for many years, research is now starting to take into account the directional distribution of neutron workplace fields. Existing neutron dosimetry instrumentation does not account for this directional distribution, resulting in conservative estimates of dose in neutron workplace fields (b...

journal_title：Medical physics

authors： Balmer MJ,Gamage KA,Taylor GC

更新日期：2016-11-01 00:00:00

abstract：PURPOSE:The primary objective of this work is to measure the secondary neutron field produced by an uncollimated proton pencil beam impinging on different tissue-equivalent phantom materials using organic scintillation detectors. Additionally, the Monte Carlo code mcnpx-PoliMi was used to simulate the detector response...

journal_title：Medical physics

authors： Clarke SD,Pryser E,Wieger BM,Pozzi SA,Haelg RA,Bashkirov VA,Schulte RW

更新日期：2016-11-01 00:00:00

abstract：PURPOSE:To present a system for robotic 4D ultrasound (US) imaging concurrent with radiotherapy beam delivery and estimate the proportion of liver stereotactic ablative body radiotherapy (SABR) cases in which robotic US image guidance can be deployed without interfering with clinically used VMAT beam configurations. M...

journal_title：Medical physics

authors： Schlosser J,Gong RH,Bruder R,Schweikard A,Jang S,Henrie J,Kamaya A,Koong A,Chang DT,Hristov D

更新日期：2016-11-01 00:00:00

abstract：PURPOSE:Radioembolization with yttrium-90 microspheres may be optimized with patient-specific pretherapy treatment planning. Dose verification and validation of treatment planning methods require quantitative imaging of the post-therapy distribution of yttrium-90 (Y-90). Methods for quantitative imaging of Y-90 using b...

journal_title：Medical physics

authors： Yue J,Mauxion T,Reyes DK,Lodge MA,Hobbs RF,Rong X,Dong Y,Herman JM,Wahl RL,Geschwind JH,Frey EC

更新日期：2016-10-01 00:00:00

abstract：PURPOSE:Dosimetry with ionization chambers in clinical ion beams for radiation therapy requires correction for recombination effects. However, common radiation protocols discriminate between initial and general recombination and provide no universal correction method for the presence of both recombination types in ion ...

journal_title：Medical physics

authors： Christensen JB,Tölli H,Bassler N

更新日期：2016-10-01 00:00:00

abstract：PURPOSE:To develop an individually optimized contrast-enhanced (CE) 4D-computed tomography (CT) for radiotherapy simulation in pancreatic ductal adenocarcinomas (PDA). METHODS:Ten PDA patients were enrolled. Each underwent three CT scans: a 4D-CT immediately following a CE 3D-CT and an individually optimized CE 4D-CT ...

journal_title：Medical physics

authors： Choi W,Xue M,Lane BF,Kang MK,Patel K,Regine WF,Klahr P,Wang J,Chen S,D'Souza W,Lu W

更新日期：2016-10-01 00:00:00

abstract：PURPOSE:The recent development of multifocal stereotactic radiosurgery (SRS) using a single isocenter volumetric modulated arc theory (VMAT) technique warrants a re-examination of the quality assurance (QA) tolerances for routine mechanical QA recommended by the American Association of Physicists in Medicine Task Group...

journal_title：Medical physics

authors： Faught AM,Trager M,Yin FF,Kirkpatrick J,Adamson J

更新日期：2016-10-01 00:00:00