4D maximum a posteriori reconstruction in dynamic SPECT using a compartmental model-based prior.

abstract：:Single energy x-ray analysis is explored in the context of computed tomography (CT), whereby Hounsfield numbers (HN) are used to estimate electron density N(e) and parameters that describe composition. We examine measurements with tissue substitute materials and theoretical HN for a broad range of tissues. Results are...

journal_title：Physics in medicine and biology

authors： Midgley SM

更新日期：2012-12-07 00:00:00

abstract：:In digital breast tomosynthesis (DBT), image characteristics of projection views and reconstructed volume are different and both have the advantage of detecting breast masses, e.g. reconstructed volume mitigates a tissue overlap, while projection views have less reconstruction blur artifacts. In this paper, an improve...

journal_title：Physics in medicine and biology

authors： Kim DH,Kim ST,Ro YM

更新日期：2015-11-21 00:00:00

abstract：:Absorbed dose values were determined under the reference conditions in a phantom irradiated by high-energy photon beams with quality varying between 60Co gamma rays and 25 MV X-rays, using four commonly employed types of ionisation chamber. The ionisation chamber readings were converted to absorbed dose values applyin...

journal_title：Physics in medicine and biology

authors： Mijnheer BJ,Wittkämper FW

更新日期：1986-04-01 00:00:00

abstract：:Radiotherapy treatment planning is associated with uncertainties. Examples are uncertainties in the tumour location due to organ movement or the inter/intra observer variability in target definition. Different approaches to incorporate uncertainties into IMRT optimization have been proposed. In this note, we point out...

journal_title：Physics in medicine and biology

authors： Unkelbach J,Oelfke U

更新日期：2006-12-07 00:00:00

abstract：:The amount of silica in the human lung may be estimated by measurement of silicon using in vivo neutron activation analysis. A pulsed, fast neutron beam, produced with a 2 MV Van de Graaff generator using the 2H + 2H reaction, was used to irradiate a Si-doped chest phantom in order to determine minimum detection limit...

journal_title：Physics in medicine and biology

authors： Kacperek A,Ryde SJ,Evans CJ,Dutton J,Morgan WD,Sivyer A

更新日期：1993-06-01 00:00:00

abstract：:Persistence of the video signal between TV frames, an effect also known as image lag, can lead to anomalously good contrast-detail test results for fluoroscopy systems. In this practical paper, a simple method is described which quantifies lag in fluoroscopy systems and corrects for its effect on threshold contrast. A...

journal_title：Physics in medicine and biology

authors： Marshall NW,Kotre CJ

更新日期：2002-03-21 00:00:00

abstract：:Dynamic PET image reconstruction is a challenging issue due to the low SNR and the large quantity of spatio-temporal data. We propose a robust state-space image reconstruction (SSIR) framework for activity reconstruction in dynamic PET. Unlike statistically-based frame-by-frame methods, tracer kinetic modeling is inco...

journal_title：Physics in medicine and biology

authors： Tong S,Alessio AM,Kinahan PE,Liu H,Shi P

更新日期：2011-04-21 00:00:00

abstract：:Using Cherenkov radiation in positron emission tomography (PET) has the potential to improve the time of flight (TOF) resolution and reduce the cost of detectors. In previous studies promising TOF results were achieved when lead fluoride (PbF2) crystals were used instead of a scintillator. In this work, a whole-body P...

journal_title：Physics in medicine and biology

authors： Consuegra D,Korpar S,Križan P,Pestotnik R,Razdevšek G,Dolenec R

更新日期：2020-03-06 00:00:00

abstract：:The function of the placenta is challenging to characterize and as a result is understudied, despite the growing awareness of the impact of the placental environment on human health and development. Medical imaging has the potential to improve our ability to screen for diseases associated with placental insufficiency,...

journal_title：Physics in medicine and biology

authors： Wu C,Bayer CL

更新日期：2018-07-09 00:00:00

abstract：:The inadequate visibility of microcalcifications-small calcium deposits that cue radiologists to early stages of cancer-is a major limitation in current designs of dedicated breast computed tomography (bCT). This limitation has previously been attributed to the constituent components, spatial resolution, and utilized ...

journal_title：Physics in medicine and biology

authors： Ghazi P

更新日期：2020-12-04 00:00:00

abstract：:To calculate photon spectra for a 10 MV x-ray beam emitted by a medical linear accelerator, we performed numerical analysis using the aluminium transmission data obtained along the central axis of the beam under the narrow beam condition corresponding to a 3x3 cm2 field at a 100 cm distance from the source. We used th...

journal_title：Physics in medicine and biology

authors： Shimozato T,Tabushi K,Kitoh S,Shiota Y,Hirayama C,Suzuki S

更新日期：2007-01-21 00:00:00

abstract：:A micro-multileaf collimator (microMLC) for stereotactic radiosurgery is used for determination of the spatial intensity distribution of the photon source of a linear accelerator. The method is based on grid field dose measurements using film dosimetry and is easy to perform. Since the microMLC does not allow 'direct'...

journal_title：Physics in medicine and biology

authors： Treuer H,Hoevels M,Luyken K,Hunsche S,Kocher M,Müller RP,Sturm V

更新日期：2003-08-07 00:00:00

abstract：:The purpose of this work was to study and quantify the differences in dose distributions computed with some of the newest dose calculation algorithms available in commercial planning systems. The study was done for clinical cases originally calculated with pencil beam convolution (PBC) where large density inhomogeneit...

journal_title：Physics in medicine and biology

authors： Hasenbalg F,Neuenschwander H,Mini R,Born EJ

更新日期：2007-07-07 00:00:00

abstract：:Skin toxicity has been reported for IMRT of head and neck cancer. The purpose of this study was to investigate the dose in the build-up region delivered by a 6 MV treatment plan for which important skin toxicity was observed. We also investigated if the different designs of the treatment head of an Elekta and a Varian...

journal_title：Physics in medicine and biology

authors： Paelinck L,De Wagter C,Van Esch A,Duthoy W,Depuydt T,De Neve W

更新日期：2005-02-07 00:00:00

abstract：:For quality assurance of hyperthermia treatment planning systems, quantitative validation of the electromagnetic model of an applicator is essential. The objective of this study was to validate a finite-difference time-domain (FDTD) model implementation of the Lucite cone applicator (LCA) for superficial hyperthermia....

journal_title：Physics in medicine and biology

authors： de Bruijne M,Samaras T,Chavannes N,van Rhoon GC

更新日期：2007-06-07 00:00:00

abstract：:The in vivo electric conductivity (σ) values of tissue are essential for accurate electromagnetic simulations and specific absorption rate (SAR) assessment for applications such as thermal dose computations in hyperthermia. Currently used σ-values are mostly based on ex vivo measurements. In this study the conductivit...

journal_title：Physics in medicine and biology

authors： Balidemaj E,de Boer P,van Lier AL,Remis RF,Stalpers LJ,Westerveld GH,Nederveen AJ,van den Berg CA,Crezee J

更新日期：2016-02-21 00:00:00

abstract：:The advent of real-time ultrasound in the 1970s, together with a growing interest in tissue characterization, led to a number of investigators using the nature of tissue motion to distinguish healthy from diseased tissue. Our group at the (then) Ultrasonics Institute demonstrated the use of phase methods for detecting...

journal_title：Physics in medicine and biology

authors： Wilson LS,Robinson DE,Dadd MJ

更新日期：2000-06-01 00:00:00

abstract：:Micro-CT is widely used in preclinical studies, generating substantial interest in extending its capabilities in functional imaging applications such as blood perfusion and cardiac function. However, imaging cardiac structure and function in mice is challenging due to their small size and rapid heart rate. To overcome...

journal_title：Physics in medicine and biology

authors： Holbrook M,Clark DP,Badea CT

更新日期：2018-01-09 00:00:00

abstract：:Backscatter factors for orthovoltage x-ray beams are fitted with the expression BSF = 1 + ms/(s + n), where s is field size and m and n are adjustable parameters. The accuracy is better than 0.5%. Good results were also obtained for Cs-137 gamma rays at depth 0.12 cm and Co-60 gamma rays at depth 0.5 cm using the same...

journal_title：Physics in medicine and biology

authors： Xiao Y,Bjärngard B

更新日期：1998-05-01 00:00:00

abstract：:To generate large thermal lesions in ultrasound thermal therapy, cooling intermissions are usually introduced during the treatment to prevent near-field heating, which leads to a long treatment time. A possible strategy to shorten the total treatment time is to eliminate the cooling intermissions. In this study, the t...

journal_title：Physics in medicine and biology

authors： Liu HL,Chen YY,Yen JY,Lin WL

更新日期：2003-05-07 00:00:00

abstract：:The performance of a light sharing and recirculation mechanism that allows the extraction of depth of interaction (DOI) are investigated in this paper, with a particular focus on timing. In parallel, a method to optimize the coincidence time resolution (CTR) of PET detectors by use of the DOI information is proposed a...

journal_title：Physics in medicine and biology

authors： Pizzichemi M,Polesel A,Stringhini G,Gundacker S,Lecoq P,Tavernier S,Paganoni M,Auffray E

更新日期：2019-08-07 00:00:00

abstract：:A cost-effective method employing polysulphone, nalidixic acid, 8-methoxypsoralen and phenothiazine as UV dosimeters is presented for evaluating the UV spectrum. The exposure measured by each dosimeter is a function of the source spectrum and the spectral response of the material. Each material has a different spectra...

journal_title：Physics in medicine and biology

authors： Parisi AV,Wong JC,Moore GI

更新日期：1997-01-01 00:00:00

abstract：:In the field of regenerative medicine, there has been a growing interest in studying the combination of bone scaffolds and cells that can maximize newly formed bone. In-line phase-contrast x-ray tomography was used to image porous bone scaffolds (Skelite(©)), seeded with bone forming cells. This technique allows the q...

journal_title：Physics in medicine and biology

authors： Weber L,Langer M,Tavella S,Ruggiu A,Peyrin F

更新日期：2016-05-07 00:00:00

abstract：:Respiratory-correlated 4D-MRI can characterize respiratory-induced motion of tumors and organs-at-risk for radiotherapy treatment planning and is a necessity for image guidance of moving tumors treated on an MRI-linac. Essential for 4D-MRI generation is a robust respiratory surrogate signal. We investigated the feasib...

journal_title：Physics in medicine and biology

authors： Navest RJM,Mandija S,Bruijnen T,Stemkens B,Tijssen RHN,Andreychenko A,Lagendijk JJW,van den Berg CAT

更新日期：2020-01-13 00:00:00

abstract：:The objective of this study was to compare the lesion detection performance of human observers between thin-section computed tomography images of the breast, with thick-section (>40 mm) simulated projection images of the breast. Three radiologists and six physicists each executed a two alterative force choice (2AFC) s...

journal_title：Physics in medicine and biology

authors： Chen L,Boone JM,Abbey CK,Hargreaves J,Bateni C,Lindfors KK,Yang K,Nosratieh A,Hernandez A,Gazi P

更新日期：2015-04-21 00:00:00

abstract：:An acardiac twin is a severely malformed monochorionic twin fetus that lacks most organs, particularly a heart. It grows during pregnancy, because it is perfused by its developmentally normal co-twin (called the pump twin) via a set of placental arterioarterial and venovenous anastomoses. The pump twin dies intrauteri...

journal_title：Physics in medicine and biology

authors： Umur A,van Gemert MJ,van den Wijngaard JP,Ross MG,Nikkels PG

更新日期：2004-07-21 00:00:00

abstract：:Magnetic resonance-guided radiation therapy (MR-GRT) offers great potential to improve radiation treatment outcomes by providing more accurate and patient-tailored therapy. Despite superior soft tissue contrast in MRI, one of the challenges towards MRI-only workflows is that the process often requires some sort of 'MR...

journal_title：Physics in medicine and biology

authors： Nosrati R,Paudel M,Ravi A,Pejovic-Milic A,Morton G,Stanisz GJ

更新日期：2019-07-16 00:00:00

abstract：:This is a proof of principle study on an algorithm for optimizing external beam radiotherapy in terms of both photon beamlet energy and fluence. This simultaneous beamlet energy and fluence optimization is denoted modulated photon radiotherapy (XMRT). XMRT is compared with single-energy intensity modulated radiotherap...

journal_title：Physics in medicine and biology

authors： McGeachy P,Villarreal-Barajas JE,Zinchenko Y,Khan R

更新日期：2016-02-21 00:00:00

abstract：:Recent developments in the technique of constant infusion and in emission computed tomography have provided a new method for quantitative regional flow measurements. This paper re-examines critically the theoretical relationship between flow and radioactivity during constant infusion of short-lived isotopes. Sensitivi...

journal_title：Physics in medicine and biology

authors： Huang SC,Phelps ME,Hoffman EJ,Kuhl DE

更新日期：1979-11-01 00:00:00

abstract：:An efficient registration strategy is described that aims to help solve delicate medical imaging registration problems. It consists of running several registration methods for each dataset and selecting the best one for each specific dataset, according to an evaluation criterion. Finally, the quality of the registrati...

journal_title：Physics in medicine and biology

authors： Tacchella JM,Roullot E,Lefort M,Cohen ME,Guillevin R,Petrirena G,Delattre JY,Habert MO,Yeni N,Kas A,Frouin F

更新日期：2014-11-21 00:00:00