Asymmetric travel‐time prestack migration method

2009 ◽  
Author(s):  
Hong Liu ◽  
Guofeng Liu ◽  
Youming Li
Keyword(s):  
Travel Time ◽  
Prestack Migration ◽  
Migration Method

True‐amplitude seismic migration: A comparison of three approaches

Geophysics ◽  
1997 ◽  
Vol 62 (3) ◽  
pp. 929-936 ◽  
Author(s):  
Samuel H. Gray
Keyword(s):  
Elastic Parameter ◽  
Reflection Point ◽  
Seismic Migration ◽  
Amplitude Variation With Offset ◽  
Prestack Migration ◽  
Fundamental Limitations ◽  
Common Depth Point ◽  
Seismic Records ◽  
Migration Method ◽  
Angle Dependent Reflectivity

Knowledge of elastic parameter (compressional and shear velocities and density) contrasts within the earth can yield knowledge of lithology changes. Elastic parameter contrasts manifest themselves on seismic records as angle‐dependent reflectivity. Interpretation of angle‐dependent reflectivity, or amplitude variation with offset (AVO), on unmigrated records is often hindered by the effects of common‐depth‐point smear, incorrectly specified geometrical spreading loss, source/receiver directivity, as well as other factors. It is possible to correct some of these problems by analyzing common‐reflection‐point gathers after prestack migration, provided that the migration is capable of undoing all the amplitude distortions of wave propagation between the sources and the receivers. A migration method capable of undoing such distortions and thus producing angle‐dependent reflection coefficients at analysis points in a lossless, isotropic, elastic earth is called a “true‐amplitude migration.” The principles of true‐amplitude migration are simple enough to allow several methods to be considered as “true‐amplitude.” I consider three such migration methods in this paper: one associated with Berkhout, Wapenaar, and co‐workers at Delft University; one associated with Bleistein, Cohen, and co‐workers at Colorado School of Mines and, more recently, Hubral and co‐workers at Karlsruhe University; and a third introduced by Tarantola and developed internationally by many workers. These methods differ significantly in their derivations, as well as their implementation and applicability. However, they share some fundamental similarities, including some fundamental limitations. I present and compare summaries of the three methods from a unified perspective. The objective of this comparison is to point out the similarities of these methods, as well as their relative strengths and weaknesses.

Socioeconomic patient benefits of a pediatric neurosurgery telemedicine clinic

2020 ◽  
Vol 25 (2) ◽  
pp. 204-208 ◽  
Author(s):  
Kelsey Hayward ◽  
Sabrina H. Han ◽  
Alexander Simko ◽  
Hector E. James ◽  
Philipp R. Aldana
Keyword(s):  
Travel Time ◽  
Cost Savings ◽  
Transportation Cost ◽  
Pediatric Neurosurgery ◽  
University Of Florida ◽  
Remote Location ◽  
Socioeconomic Data ◽  
The University ◽  
Time Away

OBJECTIVEThe objective of this study was to examine the socioeconomic benefits to the patients and families attending a regional pediatric neurosurgery telemedicine clinic (PNTMC).METHODSA PNTMC was organized by the Division of Pediatric Neurosurgery of the University of Florida College of Medicine–Jacksonville based at Wolfson Children’s Hospital and by the Children’s Medical Services (CMS) to service the Southeast Georgia Health District. Monthly clinics are held with the CMS nursing personnel at the remote location. A retrospective review of the clinic population was performed, socioeconomic data were extracted, and cost savings were calculated.RESULTSClinic visits from August 2011 through January 2017 were reviewed. Fifty-five patients were seen in a total of 268 initial and follow-up PNTMC appointments. The average round-trip distance for a family from home to the University of Florida Pediatric Neurosurgery (Jacksonville) clinic location versus the PNTMC remote location was 190 versus 56 miles, respectively. The families saved an average of 2.5 hours of travel time and 134 miles of travel distance per visit. The average transportation cost savings for all visits per family and for all families was $180 and $9711, respectively. The average lost work cost savings for all visits per family and for all families was $43 and $2337, respectively. The combined transportation and work cost savings for all visits totaled $223 per family and $12,048 for all families. Average savings of $0.68/mile and $48.50/visit in utilizing the PNTMC were calculated.CONCLUSIONSManaging pediatric neurosurgery patients and their families via telemedicine is feasible and saves families substantial travel time, travel cost, and time away from work.

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