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Conceptual questions

Why is a PET scan more accurate than a SPECT scan?

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Isotopes that emit α radiation are relatively safe outside the body and exceptionally hazardous inside. Explain why.

Alpha particles do not penetrate materials such as skin and clothes easily. (Recall that alpha radiation is barely able to pass through a thin sheet of paper.) However, when produce inside the body, neighboring cells are vulnerable.

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Ionizing radiation can impair the ability of a cell to repair DNA. What are the three ways the cell can respond?

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Problems

What is the dose in mSv for: (a) a 0.1-Gy X-ray? (b) 2.5 mGy of neutron exposure to the eye? (c) 1.5m Gy of α exposure?

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Find the radiation dose in Gy for: (a) A 10-mSv fluoroscopic X-ray series. (b) 50 mSv of skin exposure by an α emitter. (c) 160 mSv of β and γ rays from the 40 K in your body.

Gy = Sv RBE : a. 0.01 Gy; b. 0.0025 Gy; c. 0.16 Gy

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Find the mass of 239 P u that has an activity of 1.00 μCi .

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In the 1980s, the term picowave was used to describe food irradiation in order to overcome public resistance by playing on the well-known safety of microwave radiation. Find the energy in MeV of a photon having a wavelength of a picometer.

1.24 MeV

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What is the dose in Sv in a cancer treatment that exposes the patient to 200 Gy of γ rays?

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One half the γ rays from 99 m T c are absorbed by a 0.170-mm-thick lead shielding. Half of the γ rays that pass through the first layer of lead are absorbed in a second layer of equal thickness. What thickness of lead will absorb all but one in 1000 of these γ rays?

1.69 mm

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How many Gy of exposure is needed to give a cancerous tumor a dose of 40 Sv if it is exposed to α activity?

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A plumber at a nuclear power plant receives a whole-body dose of 30 mSv in 15 minutes while repairing a crucial valve. Find the radiation-induced yearly risk of death from cancer and the chance of genetic defect from this maximum allowable exposure.

For cancer: ( 3 rem ) ( 10 10 6 rem · y ) = 30 10 6 y , The risk each year of dying from induced cancer is 30 in a million. For genetic defect: ( 3 rem ) ( 3.3 10 6 rem · y ) = 9.9 10 6 y , The chance each year of an induced genetic defect is 10 in a million.

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Calculate the dose in rem/y for the lungs of a weapons plant employee who inhales and retains an activity of 1.00 μ Ci 239 Pu in an accident. The mass of affected lung tissue is 2.00 kg and the plutonium decays by emission of a 5.23-MeV α particle. Assume a RBE value of 20.

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Additional problems

The wiki-phony site states that the atomic mass of chlorine is 40 g/mol. Check this result. Hint: The two, most common stable isotopes of chlorine are: 17 35 Cl and 17 37 Cl . (The abundance of Cl-35 is 75.8 % , and the abundance of Cl-37 is 24.2 % .)

atomic mass ( Cl ) = 35.5 g/mol

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A particle physicist discovers a neutral particle with a mass of 2.02733 u that he assumes is two neutrons bound together.

(a) Find the binding energy.

(b) What is unreasonable about this result?

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A nuclear physicist finds 1.0 μ g of 236 U in a piece of uranium ore ( T 1/2 = 2.348 × 10 7 y ). (a) Use the decay law to determine how much 236 U would had to have been on Earth when it formed 4.543 × 10 9 y ago for 1.0 μ g to be left today. (b) What is unreasonable about this result? (c) How is this unreasonable result resolved?

a. 1.71 × 10 58 kg ; b. This mass is impossibly large; it is greater than the mass of the entire Milky Way galaxy. c. 236 U is not produced through natural processes operating over long times on Earth, but through artificial processes in a nuclear reactor.

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Questions & Answers

how does colour appear in thin films
Nwjwr Reply
in the wave equation y=Asin(kx-wt+¢) what does k and w stand for.
Kimani Reply
derivation of lateral shieft
James Reply
Hi
Amjad
Hi
Amjad
hi
ALFRED
how are you?
Amjad
hi
asif
hi
Imran
I'm fine
ALFRED
total binding energy of ionic crystal at equilibrium is
All Reply
How does, ray of light coming form focus, behaves in concave mirror after refraction?
Bishesh Reply
Refraction does not occur in concave mirror. If refraction occurs then I don't know about this.
Sushant
What is motion
Izevbogie Reply
Anything which changes itself with respect to time or surrounding
Sushant
good
Chemist
and what's time? is time everywhere same
Chemist
No
Sushant
how can u say that
Chemist
do u know about black hole
Chemist
Not so more
Sushant
Radioactive substance
DHEERAJ
These substance create harmful radiation like alpha particle radiation, beta particle radiation, gamma particle radiation
Sushant
But ask anything changes itself with respect to time or surrounding A Not any harmful radiation
DHEERAJ
explain cavendish experiment to determine the value of gravitational concept.
Celine Reply
For the question about the scuba instructor's head above the pool, how did you arrive at this answer? What is the process?
Evan Reply
as a free falling object increases speed what is happening to the acceleration
Success Reply
of course g is constant
Alwielland
acceleration also inc
Usman
which paper will be subjective and which one objective
jay
normal distributiin of errors report
Dennis
normal distribution of errors
Dennis
photo electrons doesn't emmit when electrons are free to move on surface of metal why?
Rafi Reply
What would be the minimum work function of a metal have to be for visible light(400-700)nm to ejected photoelectrons?
Mohammed Reply
give any fix value to wave length
Rafi
40 cm into change mm
Arhaan Reply
40cm=40.0×10^-2m =400.0×10^-3m =400mm. that cap(^) I have used above is to the power.
Prema
i.e. 10to the power -2 in the first line and 10 to the power -3 in the the second line.
Prema
there is mistake in my first msg correction is 40cm=40.0×10^-2m =400.0×10^-3m =400mm. sorry for the mistake friends.
Prema
40cm=40.0×10^-2m =400.0×10^-3m =400mm.
Prema
this msg is out of mistake. sorry friends​.
Prema
what is physics?
sisay Reply
why we have physics
Anil Reply
because is the study of mater and natural world
John
because physics is nature. it explains the laws of nature. some laws already discovered. some laws yet to be discovered.
Yoblaze
physics is the study of non living things if we added it with biology it becomes biophysics and bio is the study of living things tell me please what is this?
tahreem
physics is the study of matter,energy and their interactions
Buvanes
all living things are matter
Buvanes
why rolling friction is less than sliding friction
tahreem
thanks buvanas
tahreem
is this a physics forum
Physics Reply

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Source:  OpenStax, University physics volume 3. OpenStax CNX. Nov 04, 2016 Download for free at http://cnx.org/content/col12067/1.4
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