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15:44
Exposure of children to ionizing radiation most commonly is from the environment, chiefly through cosmic rays and radon, or from medical technology. Medical radiation exposure occurs during diagnosis, therapy, and dental radiography. More is known about the biological effects of exposure to ionizing radiation than to nonionizing radiation from microwaves, radiowaves, and the electrical fields of other electrical appliances. This review applies only to sources of ionizing radiation and does not include the potential risks of indoor radon. The effects on children of ionizing radiation have been studied from war activities and environmental accidents. Protections are mode from that data to help pediatricians evaluate risk from radiation when ordering radiographs.
28 Jun 2017
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15:44
Radiation includes High-energy electromagnetic waves (x-rays, gamma rays) Particles (alpha particles, beta particles, neutrons) Alpha particles are energetic helium nuclei emitted by some radionuclides with high atomic numbers (eg, plutonium, radium, uranium); they cannot penetrate skin beyond a shallow depth (< 0.1 mm). Beta particles are high-energy electrons that are emitted from the nuclei of unstable atoms (eg, cesium-137, iodine-131). These particles can penetrate more deeply into skin (1 to 2 cm) and cause both epithelial and subepithelial damage. Neutrons are electrically neutral particles emitted by a few radionuclides (eg, californium-252) and produced in nuclear fission reactions (eg, in nuclear reactors); their depth of tissue penetration varies from a few millimeters to several tens of centimeters, depending on their energy. They collide with the nuclei of stable atoms, resulting in emission of energetic protons, alpha and beta particles, and gamma radiation. Gamma radiation and x-rays are electromagnetic radiation (ie, photons) of very short wavelength that can penetrate deeply into tissue (many centimeters). While some photons deposit all their energy in the body, other photons of the same energy may only deposit a fraction of their energy and others may pass completely through the body without interacting. Because of these characteristics, alpha and beta particles cause the most damage when the radioactive atoms that emit them are within the body (internal contamination) or, in the case of beta-emitters, directly on the body; only tissue in close proximity to the radionuclide is affected. Gamma rays and x-rays can cause damage distant from their source and are typically responsible for acute radiation syndromes (ARS—see Radiation Exposure and Contamination : Acute radiation syndromes (ARS)).
21 Jul 2017
6
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2:08
To celebrate the release of Harry Potter and The Deathly Hallows Part 1 on Blu-Ray and DVD we talk to the stars at the Apollo Theatre and the fans themselves at HMV Oxford Street.
14 Apr 2011
2180
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3:35
The explosive action movie is out now on Blu-ray and DVD.
4 Jul 2011
6291
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4:15
With the visually stunning Sucker Punch coming to Blu-ray and DVD, we talk to director Zack Snyder and stars Emily Browning, Abbie Cornish, Vanessa Hudgens, Jena Malone, Jamie Chung, Oscar Isaac and Carla Gugino.
5 Aug 2011
316
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2:29
A host of familiar and similar faces head to a screening of Blitz, out on Blu-ray and DVD.
28 Sep 2011
262
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4:29
We talk to the stars of Harry Potter about the final film coming out on Blu-ray and DVD.
3 Dec 2011
299
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2:56
Watch highlights from the Rise Planet of the Apes Blu-ray and DVD launch, with passers-by and free-runners queuing to unleash their inner primate in a giant ape playground in London’s Potter’s Field.
16 Dec 2011
290
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3:37
The cast and crew of the film sit down to celebrate the release of the action movie on Blu-ray and DVD.
23 Dec 2011
356
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5:07
We talk to star Gary Oldman, director Tomas Alfredson and writer Peter Straughn about this gripping thriller now on Blu-ray and DVD.
1 Feb 2012
124
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3:06
A student has a 12 hour sleep in Waterloo station to promote the Blu-ray and DVD release of Sleeping Beauty.
27 Feb 2012
5248
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3:36
The U.S. military makes a scarred bounty hunter with warrants on his own head an offer he cannot refuse: in exchange for his freedom, he must stop a terrorist who is ready to unleash Hell on Earth.
23 Dec 2010
397
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3:35
We head to Egg Mountain to talk to Steven Spielberg's dinosaur guru, Doctor Jack Horner.
27 Oct 2011
202
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3:38
London's Victoria Station mutates with a special visit from a couple of mutants, and Jason Flemyng sits down to talk about the hit action movie.
5 Nov 2011
591
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1:35
Last weekend Harry Potter stars and fans came together at the Wizarding World of Harry Potter in Orlando, Florida to celebrate the home entertainment release of Harry Potter and the Deathly Hallows – Part 2.
19 Nov 2011
32770
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7:18
Nicole Scott discusses the on going battle between Blu-ray and HD DVD
4 Sep 2007
646
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