abstract：:This paper concerns the robustness of discrete wavelet transform (DWT) compression in terahertz pulsed imaging (TPI). TPI datasets consist of terahertz time-domain series which are sampled at each 'pixel' of the image, leading to file sizes which are typically of the order of several megabytes (MB) per image. This mak...

journal_title：Physics in medicine and biology

authors： Handley JW,Fitzgerald AJ,Berry E,Boyle RD

更新日期：2002-11-07 00:00:00

abstract：:We discuss the use of terahertz time domain spectroscopy for studies of conformational flexibility and conformational change in biomolecules. Protein structural dynamics are vital to biological function with protein flexibility affecting enzymatic reaction rates and sensory transduction cycling times. Conformational m...

journal_title：Physics in medicine and biology

authors： Markelz A,Whitmire S,Hillebrecht J,Birge R

更新日期：2002-11-07 00:00:00

abstract：:A near-field probe is described that enables high spatial resolution imaging with terahertz (THz) pulses. The spatial resolution capabilities of the system lie in the range of few microns and we demonstrate a resolution of 7 microm using broad-banded THz pulses with an intensity maximum near 0.5 THz. We present a stud...

journal_title：Physics in medicine and biology

authors： Federici JF,Mitrofanov O,Lee M,Hsu JW,Brener I,Harel R,Wynn JD,Pfeiffer LN,West KW

更新日期：2002-11-07 00:00:00

abstract：:Radiation therapy is an image-guided process whose success critically depends on the imaging modality used for treatment planning and the level of integration of the available imaging information. In this work, we establish a dose optimization framework for incorporating metabolic information from functional imaging m...

journal_title：Physics in medicine and biology

authors： Xing L,Cotrutz C,Hunjan S,Boyer AL,Adalsteinsson E,Spielman D

更新日期：2002-10-21 00:00:00

abstract：:We explore how the radioactive background from naturally occurring 176Lu affects single photon transmission imaging for lutetium orthosilicate (LSO) scintillator-based PET cameras by estimating the transmission noise equivalent count rate (NECR) including this background. Assuming a typical PET camera geometry (80 cm ...

journal_title：Physics in medicine and biology

authors： Huber JS,Moses WW,Jones WF,Watson CC

更新日期：2002-10-07 00:00:00

abstract：:Optical topography is a method for visualization of conical activity. Ways of improving the spatial resolution of the topographical image with three arrangements of optical fibres are discussed. A distribution of sensitivity is obtained from the phantom experiment, and used to reconstruct topographical images of an ac...

journal_title：Physics in medicine and biology

authors： Yamamoto T,Maki A,Kadoya T,Tanikawa Y,Yamad Y,Okada E,Koizumi H

更新日期：2002-09-21 00:00:00

abstract：:Fast heat extraction is critically important to obtain the maximal benefit of cryogen spray cooling (CSC) during laser therapy of shallow skin lesions, such as port wine stain birthmarks. However, a film of liquid cryogen can build up on the skin surface, impairing heat transfer due to the relatively low thermal condu...

journal_title：Physics in medicine and biology

authors： Majaron B,Svaasand LO,Aguilar G,Nelson JS

更新日期：2002-09-21 00:00:00

abstract：:Monte Carlo (MC) algorithms are recognized as the most accurate methodology for patient dose assessment. For intensity-modulated radiation therapy (IMRT) delivered with dynamic multileaf collimators (DMLCs), accurate dose calculation, even with MC, is challenging. Accurate IMRT MC dose calculations require inclusion o...

journal_title：Physics in medicine and biology

authors： Siebers JV,Keall PJ,Kim JO,Mohan R

更新日期：2002-09-07 00:00:00

abstract：:In recent codes of practice for reference dosimetry in clinical proton beams using ionization chambers, it is recommended to perform the measurement in a water phantom. However, in situations where the positioning accuracy is very critical, it could be more convenient to perform the measurement in a plastic phantom. I...

journal_title：Physics in medicine and biology

authors： Palmans H,Symons JE,Denis JM,de Kock EA,Jones DT,Vynckier S

更新日期：2002-09-07 00:00:00

abstract：:Several recent reports agree that the potentially dangerous heating around extended wires or coaxial cables inside the bodycoil of a magnetic resonance imager is related to resonant effects. No quantitative description of this idea has been given so far. We analyse a simplified situation, where a straight metallic wir...

journal_title：Physics in medicine and biology

authors： Pictet J,Meuli R,Wicky S,van der Klink JJ

更新日期：2002-08-21 00:00:00

abstract：:We have measured the bulk optical properties of healthy female breast tissues in vivo in the parallel plate, transmission geometry. Fifty-two volunteers were measured. Blood volume and blood oxygen saturation were derived from the optical property data using a novel method that employed a priori spectral information t...

journal_title：Physics in medicine and biology

authors： Durduran T,Choe R,Culver JP,Zubkov L,Holboke MJ,Giammarco J,Chance B,Yodh AG

更新日期：2002-08-21 00:00:00

abstract：:In this work, we investigate longitudinal sampling and aliasing effects in multi-slice helical CT. We demonstrate that longitudinal aliasing can be a significant, complicated, and potentially detrimental effect in multi-slice helical CT reconstructions. Multi-slice helical CT scans are generally undersampled longitudi...

journal_title：Physics in medicine and biology

authors： La Rivière PJ,Pan X

更新日期：2002-08-07 00:00:00

abstract：:Using iterative three-dimensional (3D) reconstruction techniques for reconstruction of positron emission tomography (PET) is not feasible on most single-processor machines due to the excessive computing time needed, especially so for the large sinogram sizes of our high-resolution research tomograph (HRRT). In our fir...

journal_title：Physics in medicine and biology

authors： Vollmar S,Michel C,Treffert JT,Newport DF,Casey M,Knöss C,Wienhard K,Liu X,Defrise M,Heiss WD

更新日期：2002-08-07 00:00:00

abstract：:Numerical computations are used to evaluate electric field dosimetry for high-resolution anatomically based inhomogeneous models of a human male child, and male and female rats and mice, under exposure to 60 Hz uniform magnetic field sources of three perpendicular orientations. The goal is to compare the child data to...

journal_title：Physics in medicine and biology

authors： Dawson TW,Caputa K,Stuchly MA

更新日期：2002-07-21 00:00:00

abstract：:Photon quality correction factors (kQy) for ionization chamber photon dosimetry in an epithermal neutron beam were determined according to a modified absorbed dose to water formalism which was extended to mixed radiation fields. We have studied two commercially available ionization chambers in the epithermal neutron b...

journal_title：Physics in medicine and biology

authors： Munck af Rosenschöld PM,Ceberg CP,Giusti V,Andreo P

更新日期：2002-07-21 00:00:00

abstract：:An x-ray fluorescence system with a synchrotron radiation source was used to quantify the levels of iron, copper and zinc in breast tissue specimens. Healthy tissue and breast carcinomas were investigated as an aid to understanding the mechanisms of breast cancer and as a possible complementary diagnostic tool. Eighty...

journal_title：Physics in medicine and biology

authors： Geraki K,Farquharson MJ,Bradley DA

更新日期：2002-07-07 00:00:00

abstract：:The dosimetrical characteristics of a new miniature multileaf collimator (ModuLeaf MLC, MRC Systems GmbH, Heidelberg, Germany) attached to the accessory holder of a Siemens accelerator with 6 MV x-rays (PRIMUS, Siemens OCS, Concord, California, USA) have been investigated. In particular, those parameters which are imp...

journal_title：Physics in medicine and biology

authors： Hartmann GH,Föhlisch F

更新日期：2002-06-21 00:00:00

abstract：:In a previous paper the calibration of an isotropic light detector in clear media was described and validated. However, in most applications the detector is used to measure light distribution in turbid (scattering) media, that is, in tissues or tissue equivalent optical phantoms. Despite its small diameter (typically ...

journal_title：Physics in medicine and biology

authors： Marijnissen JP,Star WM

更新日期：2002-06-21 00:00:00

abstract：:A comprehensive set of measurements and calculations has been conducted to investigate the accuracy of the Dose Planning Method (DPM) Monte Carlo code for electron beam dose calculations in heterogeneous media. Measurements were made using 10 MeV and 50 MeV minimally scattered, uncollimated electron beams from a racet...

journal_title：Physics in medicine and biology

authors： Chetty IJ,Moran JM,Nurushev TS,McShan DL,Fraass BA,Wilderman SJ,Bielajew AF

更新日期：2002-06-07 00:00:00

abstract：:It has been reported that the dose effects of metallic guidewires are significant in intravascular brachytherapy (IVBT) using a beta source. The purpose of this work is to investigate the dependence of these dose effects on guidewire position. The EGS4 Monte Carlo codes were used to perform the dose calculations for t...

journal_title：Physics in medicine and biology

authors： Shih R,Hsu WL,Li XA

更新日期：2002-05-21 00:00:00

abstract：:We implemented a hybrid scatter-correction method for 3D PET that combines two scatter-correction methods in a complementary way. The implemented scheme uses a method based on the discrimination of the energy of events (the estimation of trues method (ETM)) and an auxiliary method (the single scatter simulation method...

journal_title：Physics in medicine and biology

authors： Ferreira NC,Trébossen R,Lartizien C,Brulon V,Merceron P,Bendriem B

更新日期：2002-05-07 00:00:00

abstract：:The usefulness of a direct detection scheme of the second harmonic (2h) overmodulated signal from irradiated alanine in EPR dosimetry was studied. For this purpose, a group of DL-alanine/paraffin cylindrical pellets was produced. The dosimeters were irradiated with a 60Co radiotherapy gamma source with doses of 0.05, ...

journal_title：Physics in medicine and biology

authors： Chen F,Graeff CF,Baffa O

更新日期：2002-04-21 00:00:00

abstract：:Segmented attenuation correction is now a widely accepted technique to reduce noise propagation from transmission scanning in positron emission tomography (PET). In this paper, we present a new method for segmenting transmission images in whole-body scanning. This reduces the noise in the correction maps while still c...

journal_title：Physics in medicine and biology

authors： Zaidi H,Diaz-Gomez M,Boudraa A,Slosman DO

更新日期：2002-04-07 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：:We extend the theory of three-dimensional (3D) tomographic intensity modulated radiation therapy (IMRT). The geometry consists of two-dimensional modulated beams on a sphere centred in the tumour. The theory provides an efficient algorithm for computing beam modulation patterns that approximately 'reconstruct' the pre...

journal_title：Physics in medicine and biology

authors： Levine RY,Braunstein M

更新日期：2002-03-07 00:00:00

abstract：:This is a review of the relatively recently developed field of intravascular brachytherapy of coronary arteries. It presents a brief overview of the discipline of coronary angioplasty describing the problem of restenosis and discusses the potential for ionizing radiation to overcome this problem. It examines the vario...

journal_title：Physics in medicine and biology

authors： Fox RA

更新日期：2002-02-21 00:00:00

abstract：:Magnetoencephalography (MEG) is a non-invasive functional imaging modality based on the measurement of the external magnetic field produced by neural current sources within the brain. The reconstruction of the underlying sources is a severely ill-posed inverse problem typically tackled using either low-dimensional par...

journal_title：Physics in medicine and biology

authors： Jerbi K,Mosher JC,Baillet S,Leahy RM

更新日期：2002-02-21 00:00:00

abstract：:The National Physical Laboratory (NPL) provides a high-energy photon calibration service using 4-19 MV x-rays and 60Co gamma-radiation for secondary standard dosemeters in terms of absorbed dose to water. The primary standard used for this service is a graphite calorimeter and so absorbed dose calibrations must be con...

journal_title：Physics in medicine and biology

authors： Nutbrown RF,Duane S,Shipley DR,Thomas RA

更新日期：2002-02-07 00:00:00

abstract：:The design and performance of a dosimetric system for the irradiation of thin biological samples with therapeutic proton beams is reported. Protons with initial energies between 40 MeV and 250 MeV are degraded with polystyrene blocks of variable thickness in order to place the sample, an aqueous layer of 10 microm thi...

journal_title：Physics in medicine and biology

authors： Bashkirov V,Schulte RW

更新日期：2002-02-07 00:00:00

abstract：:This paper presents a computerized method for the selection of an irregular region of interest (ROI) in broadband ultrasound attenuation (BUA) images. A region growing algorithm searches an initial region in the posterior part of the calcaneus until the pixel with the lowest attenuation value is found; this is the sta...

journal_title：Physics in medicine and biology

authors： Damilakis J,Stratakis J,Perisinakis K,Gourtsoyiannis N

更新日期：2002-01-21 00:00:00

abstract：:Voxel phantoms are human models based on computed tomographic or magnetic resonance images obtained from high-resolution scans of a single individual. They consist of a huge number of volume elements (voxels) and are at the moment the most precise representation of the human anatomy. The purpose of this paper is to in...

journal_title：Physics in medicine and biology

authors： Petoussi-Henss N,Zanki M,Fill U,Regulla D

更新日期：2002-01-07 00:00:00

abstract：:We present the results of utilizing aligned anatomical information from CT images to locally adjust image smoothness during the reconstruction of three-dimensional (3D) whole-body positron emission tomography (PET) data. The ability of whole-body PET imaging to detect malignant neoplasms is becoming widely recognized....

journal_title：Physics in medicine and biology

authors： Comtat C,Kinahan PE,Fessler JA,Beyer T,Townsend DW,Defrise M,Michel C

更新日期：2002-01-07 00:00:00

abstract：:Methods based on magnetic resonance imaging for the measurement of three-dimensional distributions of radiation dose are highly developed. However, relatively little work has been done on optical computed tomography (OCT). This paper describes a new OCT scanner based on a broad beam light source and a two-dimensional ...

journal_title：Physics in medicine and biology

authors： Doran SJ,Koerkamp KK,Bero MA,Jenneson P,Morton EJ,Gilboy WB

更新日期：2001-12-01 00:00:00

abstract：:Monte Carlo simulation of beam modifiers such as physical wedges and compensating filters has been performed with a rectilinear voxel geometry module. A modified version of the EGS4/DOSXYZ code has been developed for this purpose. The new implementations have been validated against the BEAM Monte Carlo code using its ...

journal_title：Physics in medicine and biology

authors： Spezi E,Lewis DG,Smith CW

更新日期：2001-11-01 00:00:00

abstract：:The electron pencil-beam redefinition algorithm (PBRA), which is used to calculate electron beam dose distributions, assumes that the virtual source of each pencil beam is identical to that of the broad beam incident on the patient. In the present work, a virtual source specific for each pencil beam is modelled by inc...

journal_title：Physics in medicine and biology

authors： Boyd RA,Hogstrom KR,White RA,Starkschall G

更新日期：2001-11-01 00:00:00

abstract：:This paper presents a description of tests carried out to compare the behaviour of five algorithms in inverse radiation therapy planning: (1) The Dynamically Penalized Likelihood (DPL), an algorithm based on statistical estimation theory; (2) an accelerated version of the same algorithm: (3) a new fast adaptive simula...

journal_title：Physics in medicine and biology

authors： Llacer J,Solberg TD,Promberger C

更新日期：2001-10-01 00:00:00

abstract：:This study verifies the concept of the super-omni wedge by validating its equations for effective wedge orientation and wedge angle and by comparing the dose distributions it produces with those produced by other wedge techniques. To validate the equations, we calculated dose distributions for 20 combinations of wedge...

journal_title：Physics in medicine and biology

authors： Dai J,Zhu Y,Wu X

更新日期：2001-09-01 00:00:00

abstract：:Corrections for room scatter, [ksc(d, H)]RM, were derived using Monte Carlo methods for rooms of various sizes, including the brachytherapy treatment room, in which primary air kerma strength standardization of a remote afterloading microSelectron 192Ir HDR source was carried out, using a 60 cm3 spherical graphite ion...

journal_title：Physics in medicine and biology

authors： Selvam TP,Rajan KN,Nagarajan PS,Sethulakshmi P,Bhatt BC

更新日期：2001-09-01 00:00:00

abstract：:Indocyanine green (ICG) is a near-infrared dye that has the potential to be used as a tracer for the minimally invasive measurement of cerebral blood flow (CBF). In order to examine the technique, the arterial and cerebral concentrations of ICG were measured in newborn piglets during the bolus passage of ICG at normoc...

journal_title：Physics in medicine and biology

authors： Springett R,Sakata Y,Delpy DT

更新日期：2001-08-01 00:00:00

abstract：:We combine two near-infrared diffuse optical techniques to study variations of blood flow, haemoglobin concentration, and blood oxygen saturation in the functioning rat brain. Diffuse correlation spectroscopy (or flowmetry) monitors changes in the cerebral blood flow, without the use of the principles of tracer cleara...

journal_title：Physics in medicine and biology

authors： Cheung C,Culver JP,Takahashi K,Greenberg JH,Yodh AG

更新日期：2001-08-01 00:00:00