Quantcast Figure 2-24. Spinning-top test. - Fundamentals of X-Ray Physics

Share on Google+Share on FacebookShare on LinkedInShare on TwitterShare on DiggShare on Stumble Upon
Custom Search
 
  
 
Figure 2-24. Spinning-top test.
a. The "top" is a flat metal disk with a small hole drilled near one edge (figure
2-24A); it is placed above an x-ray film or cassette and made to spin while a short
exposure is made. In fully rectified current of 60 cycles, there are 120 pulsations a
second (with a half-wave rectifier there are 60): x-rays are produced by each of these
pulsations. The developed film will show a dot for each pulsation occurring during the
given exposure time. If all four rectifiers are operating properly, there will be one dot for
each 1/120 second of exposure used (60-cycle AC).
b. For example, for an exposure obtained in 1/10 second, 12 dark dots should
show on the film (figure 2-24B); if only 6 dots show (figure 2-24C) there were only 6
pulsations in 1/10 second, indicating that only half of the transformer output is reaching
the x-ray tube because one or more of the rectifiers requires replacement. The
spinning-top method may also be used to establish the accuracy of the timer.
2-35. THREE-PHASE
One and two-pulse voltage patterns are produced by x-ray generators designed
to operate on single-phase AC. Generators that operate on three- phase AC produce
6-pulse and 12-pulse tube voltage patterns. Figure 2-25 shows some characteristics of
the four patterns as well as the alternating current form. Also shown is the voltage
ripple, which is the difference between the peak and minimum voltage. Two-pulse tube
voltage, for example, drops to zero value after each peak. Consequently, two-pulse
ripple is 100 percent. On the other hand, 6-pulse and 12-pulse voltages do not drop to
zero value. In 6-pulse systems, the voltage only drops a small amount before the next
pulse has reached the same amplitude, so 6-pulse ripple is 13.5 percent. For 12-pulse,
the voltage ripple is a mere 3.4 percent.
MD0950
2-33



Medical News
Flu winds down as FDA aims for better vaccine next winter
The miserable flu season is winding down, but it's lasted...
medicalxpress.com
Atrial fibrillation patients on digoxin face increased risk of death
Patients taking digoxin to control atrial fibrillation face a 27...
medicalxpress.com
Scientists quantify healthy years gained by avoiding risk factors
Obesity, hypertension and diabetes are known risk factors for heart...
medicalxpress.com
New studies fail to find cardiovascular risk with testosterone therapy
Two studies scheduled for presentation at the American College of...
medicalxpress.com
Personalized health coaching helps reverse progression to diabetes
People with prediabetes who took part in a comprehensive health...
medicalxpress.com
Air pollution connected with narrowing of the arteries
People living in areas with more air pollution face a...
medicalxpress.com
How much sugar is in that? Seven foods with added sugar
Health officials say people should eat less sugar. But that's...
medicalxpress.com
Chinese researchers report successful hepatitis E vaccine
(HealthDay)—A new vaccine for hepatitis E provides protection from the...
medicalxpress.com
Opdivo approval expanded to include lung cancer
(HealthDay)—U.S. Food and Drug Administration approval of Opdivo (nivolumab) has...
medicalxpress.com
Common drug for irregular heartbeat tied to worse outcomes
(HealthDay)—Patients who take the heart rhythm drug digoxin may face...
medicalxpress.com
Second Los Angeles hospital reports 'superbug' infections
A second hospital in Los Angeles says several patients have...
medicalxpress.com
Novel approach helps prevent early menopause in breast cancer patients, study finds
Early menopause can be prevented and fertility may be preserved...
medicalxpress.com
Mediterranean diet cuts heart disease risk by nearly half
Adults who closely followed the Mediterranean diet were 47 percent...
medicalxpress.com
LA story: Cleaner air, healthier kids
A 20-year study finds that millennial children in Southern California...
medicalxpress.com
Omega-3 fatty acids appear to protect damaged heart after heart attack
Taking omega-3 fatty acids appeared to lower inflammation and guard...
medicalxpress.com
New protein booster may lead to better DNA vaccines and gene therapy
Scientists have discovered a new way to manipulate how cells...
medicalxpress.com
Scientists find link between flame retardants and obesity
Could your electronics be making you fat? According to University...
medicalxpress.com
Better midlife fitness may slow brain aging
People with poor physical fitness in their 40s may have...
medicalxpress.com
Engaging with art to improve clinical skills
The scene: A group of medical students huddled around the...
scopeblog.stanford.edu
Strong genetic risk factor for MS discovered in family of five affected siblings
Researchers at the University of Illinois at Chicago have identified...
medicalxpress.com
 


Privacy Statement - Copyright Information. - Contact Us

comments powered by Disqus

Integrated Publishing, Inc.
9438 US Hwy 19N #311 Port Richey, FL 34668

Phone For Parts Inquiries: (727) 755-3260
Google +