Abstract:
:An in vivo probe was compared with a gamma camera for the task of detecting radiolabelled tumour models in a water phantom. The probe, which contained a 1 cm diameter NaI(T1) detector, was designed and used by us for surgical staging studies of gynaecological patients. Tumours were spherical sources of different sizes and activities per unit volume of cobalt-57. The phantom was a tank of water (451) containing dissolved radioactivity to simulate background activity. Detector-to-source separations and tank depths were also varied. Camera images of 10 min duration were compared with probe counts of 15 s. For each configuration a large number of source and background runs were analysed using an ideal-observer ROC technique. Area under the ROC curve was used as the figure of merit. Results show that for approximately uniform background the probe should perform substantially better than the gamma camera in detecting small, deep tumours provided that the probe can be manoeuvred to within a few centimetres of the tumour. Mathematical modelling of our results indicates that this conclusion is not dependent on radiopharmaceutical dose, tumour uptake or camera type.
journal_name
Phys Med Bioljournal_title
Physics in medicine and biologyauthors
Barber HB,Barrett HH,Woolfenden JM,Myers KJ,Hickernell TSdoi
10.1088/0031-9155/34/6/008subject
Has Abstractpub_date
1989-06-01 00:00:00pages
727-39issue
6eissn
0031-9155issn
1361-6560journal_volume
34pub_type
杂志文章abstract::The biological mechanisms of platelet destruction must be correctly identified before platelet survival curves can be interpreted. This report develops a theory of platelet destruction which is compared with experiments performed on platelets labelled with the radioactive isotope 51Cr. Platelet destruction rate is a c...
journal_title:Physics in medicine and biology
pub_type: 杂志文章
doi:10.1088/0031-9155/28/12/001
更新日期:1983-12-01 00:00:00
abstract::Physical properties of a position-sensitive camera for the analysis of biodistributions of gamma- and beta-emitting radiopharmaceuticals in small animals have been studied, in order to achieve optimal operating conditions. The camera consisted of a highly segmented yttrium-aluminate perovskite (YAP) scintillator, coup...
journal_title:Physics in medicine and biology
pub_type: 杂志文章
doi:10.1088/0031-9155/50/3/n01
更新日期:2005-02-07 00:00:00
abstract::The purpose of this work is to develop and test a method to estimate the relative and absolute absorbed radiation dose from axial and spiral CT scans using a Monte Carlo approach. Initial testing was done in phantoms and preliminary results were obtained from a standard mathematical anthropomorphic model (MIRD V) and ...
journal_title:Physics in medicine and biology
pub_type: 杂志文章
doi:10.1088/0031-9155/48/16/306
更新日期:2003-08-21 00:00:00
abstract::In some medical procedures, it is difficult or impossible to maintain a line of sight for a guidance system. For such applications, people have begun to use electromagnetic trackers. Before a localizer can be effectively used for an image-guided procedure, a characterization of the localizer is required. The purpose o...
journal_title:Physics in medicine and biology
pub_type: 杂志文章
doi:10.1088/0031-9155/53/16/009
更新日期:2008-08-21 00:00:00
abstract::A bright flash of light is emitted by the plasma formed at the focus of an ophthalmic Nd: YAG laser. The purpose of this investigation is to determine whether the plasma flash constitutes a hazard to the operator. The intensity of the flash at the slit lamp eyepiece was measured and the experimentally derived value wa...
journal_title:Physics in medicine and biology
pub_type: 杂志文章
doi:10.1088/0031-9155/32/9/009
更新日期:1987-09-01 00:00:00
abstract::Motion-adaptive radiotherapy aims to deliver a conformal dose to the target tumour with minimal normal tissue exposure by compensating for tumour motion in real time. The prediction as well as the gating of respiratory motion have received much attention over the last two decades for reducing the targeting error of th...
journal_title:Physics in medicine and biology
pub_type: 杂志文章
doi:10.1088/0031-9155/60/1/233
更新日期:2015-01-07 00:00:00
abstract::EEG interictal epileptiform discharges in temporal lobe epilepsy are associated with magnetic fields. The maxima of magnetic spikes recorded over the spherical portions of the head appear fairly symmetric, whereas those over the lower temporal region often have irregular shapes. Furthermore, their magnitude is often u...
journal_title:Physics in medicine and biology
pub_type: 杂志文章
doi:10.1088/0031-9155/32/1/009
更新日期:1987-01-01 00:00:00
abstract::In modern radiotherapy the verification of complex treatments plans is often performed in inhomogeneous or even anthropomorphic phantoms. For dose verification small detectors are necessary and therefore alanine detectors are most suitable. Though the response of alanine for a wide range of clinical photon energies in...
journal_title:Physics in medicine and biology
pub_type: 杂志文章
doi:10.1088/0031-9155/61/3/N70
更新日期:2016-02-07 00:00:00
abstract::The purpose of this research is to develop a 4DCBCT-based dose assessment method for calculating actual delivered dose for patients with significant respiratory motion or anatomical changes during the course of SBRT. To address the limitation of 4DCT-based dose assessment, we propose to calculate the delivered dose us...
journal_title:Physics in medicine and biology
pub_type: 杂志文章
doi:10.1088/0031-9155/61/2/554
更新日期:2016-01-21 00:00:00
abstract::A leaf-setting algorithm is developed for generating arbitrary beam intensity profiles in discrete levels using dynamic multileaf collimators (DMLCs). The algorithm starts with the algebraic expression for the area under the beam profile. It is shown that the coefficients in this expression can be transformed into the...
journal_title:Physics in medicine and biology
pub_type: 杂志文章
doi:10.1088/0031-9155/43/6/019
更新日期:1998-06-01 00:00:00
abstract::Most solid-state detectors, including 3D dosimeters, show lower signal in the Bragg peak than expected, a process termed quenching. The purpose of this study was to investigate how variation in chemical composition of a recently developed radiochromic, silicone-based 3D dosimeter influences the observed quenching in p...
journal_title:Physics in medicine and biology
pub_type: 杂志文章
doi:10.1088/1361-6560/aa512a
更新日期:2017-02-21 00:00:00
abstract::The treatment planning process for patients with head and neck (H&N) cancer is regarded as one of the most complicated due to large target volume, multiple prescription dose levels, and many radiation-sensitive critical structures near the target. Treatment planning for this site requires a high level of human experti...
journal_title:Physics in medicine and biology
pub_type: 杂志文章
doi:10.1088/1361-6560/ab039b
更新日期:2019-03-18 00:00:00
abstract::The origin of photons emitted in optical fibres under proton irradiation has been attributed to either entirely Čerenkov radiation or light consisting of fluorescence with a substantial amount of Čerenkov radiation. The source of the light emission is assessed in order to understand why the signal from optical fibres ...
journal_title:Physics in medicine and biology
pub_type: 杂志文章
doi:10.1088/1361-6560/aaafad
更新日期:2018-03-09 00:00:00
abstract::We have shown that irradiation changes the dielectric properties of human skin at radiofrequencies. Both the dielectric constant and the conductivity of the irradiated skin decrease, especially at low frequencies. The experimental data were analysed using two bioelectric models. Relevant dielectric parameters were det...
journal_title:Physics in medicine and biology
pub_type: 杂志文章
doi:10.1088/0031-9155/39/6/001
更新日期:1994-06-01 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
pub_type: 杂志文章
doi:10.1088/0031-9155/46/10/309
更新日期:2001-10-01 00:00:00
abstract::A new system has been designed and built to validate the concept of 3D computerized angiography (CA). This system can acquire a set of 2D digital subtracted angiography images while rotating around a patient and then, using these images, reconstruct a 3D representation of the opacified vasculature. The design principl...
journal_title:Physics in medicine and biology
pub_type: 杂志文章
doi:10.1088/0031-9155/39/3/020
更新日期:1994-03-01 00:00:00
abstract::The variety of treatment options for cancer patients has increased significantly in recent years. Not only do we combine radiation with surgery and chemotherapy, new therapeutic approaches such as immunotherapy and targeted therapies are starting to play a bigger role. Physics has made significant contributions to rad...
journal_title:Physics in medicine and biology
pub_type: 杂志文章
doi:10.1088/0031-9155/61/21/R344
更新日期:2016-11-07 00:00:00
abstract::This work presents a Monte Carlo model of Leksell Gamma Knife Perfexion as well as the main parameters of the dose distribution in the standard phantom obtained using this model. The model is developed in the Geant4 simulation toolkit in a modular way which enables its reuse in other Perfexion studies. Large phase spa...
journal_title:Physics in medicine and biology
pub_type: 杂志文章
doi:10.1088/0031-9155/59/24/7609
更新日期:2014-12-21 00:00:00
abstract::Reference dosimetry in the presence of a strong magnetic field is challenging. Ionisation chambers have shown to be strongly affected by magnetic fields. There is a need for robust and stable detectors in MRI-guided radiotherapy (MRIgRT). This study investigates the behaviour of the alanine dosimeter in magnetic field...
journal_title:Physics in medicine and biology
pub_type: 杂志文章
doi:10.1088/1361-6560/ab8148
更新日期:2020-06-03 00:00:00
abstract::Despite the early recognition of the potential of proton imaging to assist proton therapy (Cormack 1963 J. Appl. Phys. 34 2722), the modality is still removed from clinical practice, with various approaches in development. For proton-counting radiography applications such as computed tomography (CT), the water-equival...
journal_title:Physics in medicine and biology
pub_type: 杂志文章
doi:10.1088/0031-9155/59/11/2569
更新日期:2014-06-07 00:00:00
abstract::Factors influencing the precision of measuring changes in the calcium content of sections of bone, including vertebrae, using reactor neutrons for partial body in vivo activation analysis have been examined and quantified. These factors include (a) the choice of incidient neutron spectrum, (b) the uniformity of activa...
journal_title:Physics in medicine and biology
pub_type: 杂志文章
doi:10.1088/0031-9155/20/1/007
更新日期:1975-01-01 00:00:00
abstract::Conversion factors, which relate the kerma-area product to effective dose, have been estimated for paediatric cardiac x-ray angiography. Monte Carlo techniques have been used to calculate the conversion factors for a wide range of projection angles for children of five ages and for adults. Correction factors are provi...
journal_title:Physics in medicine and biology
pub_type: 杂志文章
doi:10.1088/0031-9155/45/10/323
更新日期:2000-10-01 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
pub_type: 杂志文章
doi:10.1088/0031-9155/47/21/318
更新日期:2002-11-07 00:00:00
abstract::Projection and backprojection are operations that arise frequently in tomographic imaging. Recently, we proposed a new method for projection and backprojection, which we call distance-driven, and that offers low arithmetic cost and a highly sequential memory access pattern. Furthermore, distance-driven projection and ...
journal_title:Physics in medicine and biology
pub_type: 杂志文章
doi:10.1088/0031-9155/49/11/024
更新日期:2004-06-07 00:00:00
abstract::In elastography we have previously developed a tracking and correction method that estimates the axial and lateral strain components along and perpendicular to the compressor/scanning axis following an externally applied compression. However, the resulting motion is a three-dimensional problem. Therefore, in order to ...
journal_title:Physics in medicine and biology
pub_type: 杂志文章
doi:10.1088/0031-9155/45/6/311
更新日期:2000-06-01 00:00:00
abstract::'Patlak analysis' is a common approach used in Fdopa PET studies to calculate the uptake constant (Ki) of the tracer. It is assumed in the Patlak analysis that the reversible compartment of tissue radioactivity used is in effective equilibrium with the tracer in plasma. Therefore, using the data prior to equilibrium i...
journal_title:Physics in medicine and biology
pub_type: 杂志文章
doi:10.1088/0031-9155/40/7/007
更新日期:1995-07-01 00:00:00
abstract::A quantitative comparison of two full three-dimensional (3D) gel dosimetry techniques was assessed in a clinical setting: radiochromic gel dosimetry with an in-house developed optical laser CT scanner and polymer gel dosimetry with magnetic resonance imaging (MRI). To benchmark both gel dosimeters, they were exposed t...
journal_title:Physics in medicine and biology
pub_type: 杂志文章
doi:10.1088/0031-9155/58/18/6241
更新日期:2013-09-21 00:00:00
abstract::Intensity modulated proton radiotherapy (IMPT) can reduce the dose to critical structures by optimizing the distribution and intensity of individual pencil beams. The IMPT can be delivered by dynamically scanning a pencil beam with variable intensity and energy across the tumor target volume. The lateral penumbra of a...
journal_title:Physics in medicine and biology
pub_type: 杂志文章
doi:10.1088/0031-9155/53/6/016
更新日期:2008-03-21 00:00:00
abstract::Three-dimensional reconstruction of cardiac vasculature from angiographic C-arm CT (rotational angiography) data is a major challenge. Motion artefacts corrupt image quality, reducing usability for diagnosis and guidance. Many state-of-the-art approaches depend on retrospective ECG-gating of projection data for image ...
journal_title:Physics in medicine and biology
pub_type: 杂志文章
doi:10.1088/0031-9155/58/11/3717
更新日期:2013-06-07 00:00:00
abstract::The analysis of (x-ray) mammograms remains qualitative, relying on the judgement of clinicians. We present a novel method to compute a quantitative, normalized measure of tissue radiodensity traversed by the primary beam incident on each pixel of a mammogram, a measure we term the standard attenuation rate (SAR). SAR ...
journal_title:Physics in medicine and biology
pub_type: 杂志文章
doi:10.1088/0031-9155/57/20/6519
更新日期:2012-10-21 00:00:00