Abstract:
:The NSD equation, D = 1850 x T0.11 x N0.24, is a celebrated transmogrification of Cohen's two well-known collations of data on response to clinical irradiations (3 degrees erythema and 0.90 ablation of skin cancer) in which the relation of D and T is fixed by the data selected by Cohen and the additional constraint that N correspond to a schedule of five treatments per week is imposed subsequently by Ellis. The present paper shows that the equation, if correct, would have little clinical significance because the proportion, P, in which the dose, D, elicits the 3 degree erythema is unspecified: D = D(P) = D(?). Since the two Cohen collations each summarize the measurements on a different set of observational units, it is questionable whether the equation can be correct. This paper further shows that the appropriate (Least Squares) estimates of the three-parameter equation derived for the Cohen data under the Ellis constraint (five treatments per week) is in fact: D(1.0) = 1710 x T0.54 x N-0.26. The paper shows that the NSD equation is also incorrect because the ad hoc method by which Ellis estimates the exponents is inconsistent with the constraints imposed by Cohen and Ellis upon the parameters of the multivariate frequency distribution of the data set. The paper shows that the method by which the correct LS estimates of the exponents were obtained from the Cohen-Ellis data is consistent with these constraints and, therefore, this equation is a correct graduation of any other set of treatment regimens which is also consistent with the Cohen and Ellis constraints. The paper further shows that for such data sets there are, in fact, only two independent continuous variables, either D and T or D and N, since the Ellis constraint requires that N and T be collinear. Thus, the best linear graduation has the typical form: D congruent to 1900T0.32. This is "best" in the usual sense: both prediction and confidence intervals are provided for the estimates of the conditional "tolerance dose" D; these are not inflated by the presence of a collinear variable. This equation is biased, however, by the absence of the collinear variable. The TDF and the CRE concepts are derived from the NSD and, therefore, the deficiencies of the latter concept which we discuss may be expected to encumber these progeny as well. The two characteristic features of the Cohen (Ellis)-type data which impede the construction of useful estimates of the putative separate effects of N and T upon the response of tissues to irradiation are that (1) these data do not include specifications of either a tissue defect or its incidence, and (2) the variables N and T are collinear. Appendices I and II describe methods by which the effects of these features may be eliminated (I) or reduced (II).
journal_name
Med Physjournal_title
Medical physicsauthors
Herbert DE Jrdoi
10.1118/1.595034subject
Has Abstractpub_date
1981-11-01 00:00:00pages
813-47issue
6eissn
0094-2405issn
2473-4209journal_volume
8pub_type
杂志文章相关文献
MEDICAL PHYSICS文献大全abstract:PURPOSE:To evaluate two deformable image registration (DIR) algorithms for the purpose of contour mapping to support image guided adaptive radiotherapy (IGART) with 4D cone beam CT (4DCBCT). METHODS:Eleven locally advanced non-small cell lung cancer (NSCLC) patients underwent one planning 4D fan- beam CT (4DFBCT) and ...
journal_title:Medical physics
pub_type: 杂志文章
doi:10.1118/1.4735821
更新日期:2012-06-01 00:00:00
abstract::An indirect flat-panel imager (FPI) with avalanche gain is being investigated for low-dose x-ray imaging. It is made by optically coupling a structured x-ray scintillator CsI(Tl) to an amorphous selenium (a-Se) avalanche photoconductor called HARP (high-gain avalanche rushing photoconductor). The final electronic imag...
journal_title:Medical physics
pub_type: 杂志文章
doi:10.1118/1.2008428
更新日期:2005-09-01 00:00:00
abstract::Ultrasound-induced blood stasis has been observed for more than 30 years. Most of the literature has been focused on the health risks associated with this phenomenon and methods employed to prevent stasis from occurring during ultrasound imaging. To date, experimental observations have been either in vitro or invasive...
journal_title:Medical physics
pub_type: 杂志文章
doi:10.1118/1.2198196
更新日期:2006-06-01 00:00:00
abstract:PURPOSE:An original radionuclide calibrator method for activity determination is presented. The method could be used for intercomparison surveys for short half-life radioactive sources used in Nuclear Medicine, such as(99m)Tc or most positron emission tomography radiopharmaceuticals. METHODS:By evaluation of the resul...
journal_title:Medical physics
pub_type: 杂志文章
doi:10.1118/1.4884035
更新日期:2014-07-01 00:00:00
abstract:PURPOSE:Wide-angle free-air chambers (WAFACs) are used as primary standard measurement devices for establishing the air-kerma strength of low-energy, low-dose rate brachytherapy seeds. The National Research Council of Canada (NRC) is commissioning a primary standard wide-angle free-air chamber (NRC WAFAC) to serve the ...
journal_title:Medical physics
pub_type: 杂志文章
doi:10.1118/1.4951727
更新日期:2016-07-01 00:00:00
abstract:PURPOSE:We investigated the feasibility of proton tomosynthesis as daily positioning of patients and compared the results with photon tomosynthesis as an alternative to conventional portal imaging or on-board cone-beam computed tomography. METHODS:Dedicated photon-like proton beam using the passively scattered proton ...
journal_title:Medical physics
pub_type: 杂志文章
doi:10.1118/1.4734898
更新日期:2012-06-01 00:00:00
abstract::The last 50 years have seen great advances in the accuracy of external beam radiation therapy. Geometrical uncertainties have been reduced from a centimeter or more in presimulation, skin-mark guided days to 1-2 mm in today's image-guided radiation therapy treatments. Medical physicists, with the support and guidance ...
journal_title:Medical physics
pub_type: 杂志文章,评审
doi:10.1118/1.2836420
更新日期:2008-03-01 00:00:00
abstract::Current MRI nonuniformity correction techniques are reviewed and investigated. Many approaches are used to remedy this artifact, but it is not clear which method is the most appropriate in a given situation, as the applications have been with different MRI coils and different clinical applications. In this work four w...
journal_title:Medical physics
pub_type: 杂志文章,评审
doi:10.1118/1.598357
更新日期:1998-09-01 00:00:00
abstract:PURPOSE:With the increased commercial availability of intensity modulated arc therapy (IMAT) comes the need for comprehensive QA programs, covering the different aspects of this newly available technology. This manuscript proposes such a program for the RapidArc (RA) (Varian Medical Systems, Palo Alto) IMAT solution. ...
journal_title:Medical physics
pub_type: 杂志文章
doi:10.1118/1.3622672
更新日期:2011-09-01 00:00:00
abstract:PURPOSE:Magnetic resonance imaging (MRI)-guided percutaneous cryotherapy of abdominal lesions, an established procedure, uses MRI to guide and monitor the cryoablation of lesions. Methods to precisely guide cryotherapy probes with a minimum amount of trial-and-error are yet to be established. To aid physicians in attai...
journal_title:Medical physics
pub_type: 杂志文章
doi:10.1002/mp.14116
更新日期:2020-06-01 00:00:00
abstract::A computer dose model for a low energy gamma-emitting stent in a heterogeneous medium is described. The method is based on the Sievert model which is adapted to the dose-point-kernel (DPK) model to compute the dose distribution about filtered gamma sources (Sievert-DPK model). The new gamma stent model can take into a...
journal_title:Medical physics
pub_type: 杂志文章
doi:10.1118/1.1380214
更新日期:2001-07-01 00:00:00
abstract:PURPOSE:In radiotherapy (RT) based on magnetic resonance imaging (MRI) as the only modality, the information on electron density must be derived from the MRI scan by creating a so-called pseudo computed tomography (pCT). This is a nontrivial task, since the voxel-intensities in an MRI scan are not uniquely related to e...
journal_title:Medical physics
pub_type: 杂志文章
doi:10.1118/1.4914158
更新日期:2015-04-01 00:00:00
abstract::Boron neutron capture therapy (BNCT) is an experimental type of radiotherapy, presently being used to treat glioblastoma and melanoma. To improve patient safety and to determine the radiobiological characteristics of the epithermal neutron beam of Finnish BNCT facility (FiR 1) dose-response studies were carried on the...
journal_title:Medical physics
pub_type: 杂志文章
doi:10.1118/1.1517048
更新日期:2002-11-01 00:00:00
abstract::In a practical classifier design problem, the true population is generally unknown and the available sample is finite-sized. A common approach is to use a resampling technique to estimate the performance of the classifier that will be trained with the available sample. We conducted a Monte Carlo simulation study to co...
journal_title:Medical physics
pub_type: 杂志文章
doi:10.1118/1.2868757
更新日期:2008-04-01 00:00:00
abstract:PURPOSE:The image quality of dedicated cone beam breast CT (CBBCT) is limited by substantial scatter contamination, resulting in cupping artifacts and contrast-loss in reconstructed images. Such effects obscure the visibility of soft-tissue lesions and calcifications, which hinders breast cancer detection and diagnosis...
journal_title:Medical physics
pub_type: 杂志文章
doi:10.1118/1.4955121
更新日期:2016-08-01 00:00:00
abstract::An algorithm, which combines the scanning beam with dynamic collimation to generate any arbitrary intensity profile, is presented. The desired intensity profile is assumed to be piecewise linear. The dynamic collimation method used is the "sliding window." The algorithm can be used either for a given scanning beam pro...
journal_title:Medical physics
pub_type: 杂志文章
doi:10.1118/1.597672
更新日期:1996-01-01 00:00:00
abstract:PURPOSE:Multiple anatomy optimization (MAO) utilizing deformable dose accumulation on entire 4DCT data sets is implemented to overcome ambiguity between optimal dose defined on a single anatomy and optimal accumulated dose resulting from dose delivery to moving and deforming anatomy. METHODS:Six lung cancer patients a...
journal_title:Medical physics
pub_type: 杂志文章
doi:10.1118/1.4735744
更新日期:2012-06-01 00:00:00
abstract::Interstitial brachytherapy for carcinoma of the prostate is achieved through the use of a configuration of radioactive seeds placed in a manner that delivers a customized, reasonably uniform dose to the target volume. Accurate dose delivery depends on both precise seed placement and reliable seed strength in the impla...
journal_title:Medical physics
pub_type: 杂志文章
doi:10.1118/1.598877
更新日期:2000-01-01 00:00:00
abstract::The anti-scatter grid has been widely used to reject scatter and increase the perceptibility of a low-contrast object in chest radiography; however, it also attenuated the primary x-rays, resulting in a substantial loss of information and an increased relative noise level in heavily attenuated regions. A more dose eff...
journal_title:Medical physics
pub_type: 杂志文章
doi:10.1118/1.2739805
更新日期:2007-07-01 00:00:00
abstract::Optical-resolution photoacoustic microscopy (OR-PAM) has been validated as a valuable tool for label-free volumetric microvascular imaging. More importantly, the advantages of noninvasiveness and measurement consistency suggest the use of OR-PAM for chronic imaging of intact microcirculation. Here, such chronic imagin...
journal_title:Medical physics
pub_type: 信件
doi:10.1118/1.3137572
更新日期:2009-06-01 00:00:00
abstract:PURPOSE:In intensity-modulated proton therapy (IMPT), protons are used to deliver highly conformal dose distributions, targeting tumors, and sparing organs-at-risk. However, due to uncertainties in both patient setup and relative stopping power (RSP) calculation, margins are added to the treatment volume during treatme...
journal_title:Medical physics
pub_type: 杂志文章
doi:10.1002/mp.14347
更新日期:2020-09-01 00:00:00
abstract:PURPOSE:This study aims to investigate the prompt secondary gamma spectrum and thedepth-dose distributions of incident 40 MeV protons onto various phantom materials.The goal is to find a relationship between the secondary prompt gamma emissions andthe range of the incident particles. METHODS:An application was constru...
journal_title:Medical physics
pub_type: 杂志文章
doi:10.1118/1.4735388
更新日期:2012-06-01 00:00:00
abstract::A new type of radiographic film, EDR (extended dose range) film, has been recently become available for film dosimetry. It is particularly attractive for composite isodose verification of intensity modulated radiation therapy because of its low sensitivity relative to the more common Kodak XV film. For XV film, the re...
journal_title:Medical physics
pub_type: 杂志文章
doi:10.1118/1.1568979
更新日期:2003-05-01 00:00:00
abstract::A cumulative dose histogram is the graph of an integral function integrated over a domain VCR3 and is dubbed the dose-volume histogram (DVH), the dose-surface histogram (DSH) or the dose-wall histogram (DWH), depending on the dimension and structure of the region V. This paper presents a comparative study of the three...
journal_title:Medical physics
pub_type: 临床试验,杂志文章
doi:10.1118/1.1852811
更新日期:2005-02-01 00:00:00
abstract:PURPOSE:To determine if NSCLC GTV CT textures can be predictive for tumor shrinkage after proton therapy with concurrent chemotherapy. METHODS:Simulation and weekly 4DCTs were obtained from 25 patients with locally advanced NSCLC treated by proton therapy at a 74 Gy dose level with concurrent chemotherapy. In-house de...
journal_title:Medical physics
pub_type: 杂志文章
doi:10.1118/1.4735027
更新日期:2012-06-01 00:00:00
abstract:PURPOSE:Measuring and incorporating a scanner-specific point spread function (PSF) within image reconstruction has been shown to improve spatial resolution in PET. However, due to the short half-life of clinically used isotopes, other long-lived isotopes not used in clinical practice are used to perform the PSF measure...
journal_title:Medical physics
pub_type: 杂志文章
doi:10.1118/1.4870985
更新日期:2014-05-01 00:00:00
abstract:PURPOSE:To develop a probabilistic treatment planning (PTP) method which is robust to systematic patient setup errors and to compare PTP plans with plans generated using a planning target volume (PTV) margin optimized to give the same target coverage probability as the PTP plan. METHODS:Plans adhering to the RTOG-0126...
journal_title:Medical physics
pub_type: 杂志文章
doi:10.1118/1.3679856
更新日期:2012-02-01 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
pub_type: 杂志文章
doi:10.1002/mp.12104
更新日期:2017-03-01 00:00:00
abstract::Computed tomography dose index (CTDI) is a conventional indicator of the patient dose in CT studies. It is measured as the integration of the longitudinal single scan dose profile (SSDP) by using a 100-mm-long pencil ionization chamber and a single axial scan. However, the assumption that most of the SSDP is contained...
journal_title:Medical physics
pub_type: 杂志文章
doi:10.1118/1.1835571
更新日期:2005-01-01 00:00:00
abstract::Due to practical limitations in data acquisition, 3-D computed tomography systems must attempt to provide rapid reconstructions of acceptable quality from a limited number of views. The use of convolution backprojection (CBP) for image reconstruction from an inadequate number of projections, results in view aliasing a...
journal_title:Medical physics
pub_type: 杂志文章
doi:10.1118/1.598606
更新日期:1999-06-01 00:00:00