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I am writing paper on liver transplantation.

And one of the term I came across is operator-dependent. Can someone help me understand it please?

I got the definition below from this site. I still need better definition so I understand it better.

adj. a characteristic of esoteric forms of faith healing that cannot be verified scientifically because the healing process depends largely on the special skills of the practitioner that preclude systemic investigation.

In sentence.

The measurement of portal vein flow has typically been accomplished with a Doppler effect-based ultrasound [2-3]. But, with this technique a precise flow measurement at the portal vein is considered as one of the difficult tasks due to its operator-dependent nature

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Oy vey! This is such typically bloated, pretentious, hippo-in-a-tutu-&-dancing-Swan Lake academic prose it makes me retch! I deal with this kind of syntactic garbage every day. Measuring portal vein flow is typically done using Doppler ultrasound. However, the results may not be correct, because their accuracy is operator dependent. IOW, the more skilled the person using the ultrasound machine, the more accurate (not "precise") the measurement. – user21497 Apr 29 '13 at 0:36
The sample text you give contains a construction ("is considered as") which is often seen in texts by people who do not primarily speak or write in English. I think you cannot depend on the author to have used the term "operator-dependent" correctly. – MετάEd Apr 29 '13 at 3:03
@BillFranke It isn't so straightforward. Skill is relevant, but there are nuances. – Ellie Kesselman May 1 '13 at 2:43
@Feral: Nuance examples? Here's an example of "operator-dependent" that refers to reading X-rays. I fractured my left shoulder in a fall on Jan 3. Since then, I've had 10 X-rays read by 3 orthopedic surgeons & 1 physical therapist. Only 1--the most skilled surgeon & reader of X-rays--noticed that I had both a horizontal & a vertical fracture in the same part of the bone. The horizontal fracture was hard to spot. All the papers I've edited that use this phrase define it as "experienced & skilled": different operators may mean different results. Where are the nuances? Hangover? Distraction? – user21497 May 1 '13 at 3:05
@FeralOink Actually my doubt was about "operator-dependent". I don't feel competent to judge "Doppler effect-based ultrasound". – MετάEd May 1 '13 at 14:09
up vote 1 down vote accepted

I do not believe that the definition for operator dependent that you provided is correct, not in a modern medical context.

Operator dependent refers to variation in results due to medical technologists use of diagnostic equipment. It is important for the clinician to be aware of such "operator dependent" variation. It helps ascertain whether deviation from an expected ("normal" or baseline) result may be etiological (and thus due to a disease process), versus deviation that is caused by the technique used by the diagnostic technician.

Medical imaging, EEG's and EKG's are subject to operator dependent results. The abstract of this paper describes operator dependent variability in diagnostic imagery of the heart:

The purpose of this study was to evaluate variability in the quantification of myocardial perfusion images obtained by a group of experienced operators using two widely used programs... The large variability... may influence the clinical interpretation and cause false conclusions.

In the prior example, the operator was a skilled technician. The operators may be physicians. In this example, the operators are radiologists (all are M.D.'s):

We sought to assess the reproducibility of size measurements of small lung nodules examined with [tomography]... Three radiologists measured volume and diameter of 20 phantom nodules and 37 lung nodules... Operator-dependent variability of size measurements of small nodules is not negligible and should be considered in lung cancer-screening studies.

Connotation of improper technique or lack of skill is not necessarily associated with operator-dependent results. Sometimes it is, as well as the usability design of the testing device itself. This study compared the effectiveness of mammography versus ultrasound and MRI, and found that ultrasound had the same rate of false negatives due to operator-dependent error as the other two methods.

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Thanks a lot for excellent explanation. I understand it now. – user206168 Apr 28 '13 at 22:38
@user206168 You are most welcome! I am surprised that the definition for operator-dependent that you found was so non-standard. The source that you used is usually quite decent. I use it too! It has always been reliable. Also, welcome to EL&U StackExchange! Come visit us again soon. – Ellie Kesselman Apr 29 '13 at 7:58
Sure :) Your explanation was better compare to that site Thanks again. – user206168 Apr 30 '13 at 14:12

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