1.7: Radioisotopes
- Page ID
- 38587
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- Which of the following subatomic particle ratios is important to maintain nuclear stability?
- neutron/proton
- proton/electron
- negatron/neutron
- positron/electron
- neutron/alpha
- Characteristic X-rays are emitted during the nuclear reaction involving:
- gamma decay
- positron decay
- electron capture
- negatron decay
- none of the above
- If decay factors for a radionuclide 8 days and 16 days after the calibration date are 0.9 and 0.8 respectively, what will be the radioactivity of 1 millicurie of this radionuclide 24 days from now?
- 0.72 microcurie
- 0.072 millicurie
- 0.170 millicurie
- 0.89 millicurie
- 0.72 millicurie
- A crystal scintillation detector is primarily used for detecting radionuclides emitting:
- positrons
- gamma rays
- negatrons
- X-rays
- ultraviolet light
- Beta emission is the emission of:
- a proton
- an electron
- a neutron
- a ray of light of very short wavelength
- an X-ray
- Specific activity is the radioactivity as expressed in disintegrations/second per mole of a compound or atom. Which of the following has the highest specific activity?
- 125I (t1/2 = 60 days)
- 35S (t1/2 = 62 days)
- 3H (t1/2 = 12 years)
- 14C (t1/2 = 5000 years)
- 131I (t1/2 = 8 days)
- Gamma emission is the emission of:
a. a proton
b. an electron
c. a neutron
d. a ray of light of very short wavelength
e. an X-ray - In the radioactive decay of 3H atom to a 3He atom, the subatomic particle emitted from the nucleus is a (an):
- alpha particle
- electron (negatron)
- positron
- gamma ray
- neutron
- A secondary scintiliator (e.g., POPOP) is used in liquid scintillation counting:
a. to facilitate dissolution of the sample
b. to obtain a homogenous scintillation mixture
c. to enhance the counting efficiency by “wavelength shifting”
d. as the internal standard
e. to reduce chemiluminescence - 125I is used as a label because:
a. it has high specific activity
b. it is a high-energy emitter
c. it has a long half-life
d. all of the above
e. none of the above
Use the following Key to answer Questions 11 through 17
- 1,2, and 3 are correct
- 1 and 3 are correct
- 2 and 4 are correct
- only 4 is correct
- all are correct
- 125I-labeled ligands are preferable to 3H-labeled ligands in radioimmunoassays because of:
- longer shelf life
- higher specific activity
- lower cost
- gamma-emission
- During the course of radioactive decay, a proton is converted to a neutron in:
- beta decay
- alpha decay
- electron capture
- positron decay
- Scintillation counters measure light pulses. These light pulses are related to:
- ionizing radiation
- high-energy gamma rays
- high-energy beta particles
- random electrons
- The most commonly encountered radioactive emissions in the hospital laboratory are:
- alpha -1 and gamma
- alpha -1 and beta
- beta + and gamma
- beta - and gamma
- The most commonly used radioisotope(s) in the chemistry laboratory is/are:
- 125I
- 35S
- 3H
- 14C
- Radioisotopes are most commonly used to measure in antibody-based competitive assays:
- metals
- antibodies
- electrolytes
- antigens
- Instrumentation used for detecting and recording beta-emitting isotopes differs from that used for gamma emitters because a beta scintillation counter requires:
- a photomultiplier tube
- a hollow cathode lamp
- a sodium iodide crystal
- presence of a fluor
- Answer
-
- a (p. 190)
- c (p. 190-191)
- e (p. 191-192)
- b (p. 194)
- b (p. 190)
- e (p. 192)
- d (p. 191)
- b (p. 190)
- c (p. 196)
- a (p. 192)
- c (p. 192)
- d (p. 190)
- c (p. 194)
- d (p. 192)
- e (p. 192)
- c (p. 189)
- d (p. 194-197)