Physics 8 Questions

1.

Match the origination of the radionuclide with the most appropriate decay mode.

(A) Bombarding with neutrons in a reactor

(B) Bombarding with protons in a cyclotron

(C) Mining pitchblende

(i) Alpha emission

(ii) Beta minus emission

(iii) Beta plus emission

2.

True (T) or False (F). Radioactive equilibrium

(A) is secular when the half-life of the parent » half-life of the daughter

(B) requires about 6 half-lives for secular equilibrium to be established

(C) is transient if the half-life of the parent is > half-life of the daughter

(D) for a 99Mo/99mTc generator may be termed transient

(E) is established in 24 hours for a 99Mo/99mTc generator

3.

 For 99mTc decaying to 99Tc, all of the following are true EXCEPT

(A) the half-life of 99mTc is 67 hours

(B) the half-life of 99Tc is 2.l x 105 years

(C) activity is N x lambda (N = number of atoms; lambda is decay constant)

(D) lambda= 0.693/T1/2 where T1/2 is the half-life

4.

If 100 mCi 99mTc is "milked" from a 99Mo generator (at equilibrium) at 9 A.M. on Monday, then

(A) the activity of 99Mo is 50 mCi at 3 P.M. on Monday

(B) 80 mCi 99mTc can be "milked" at 9 A.M. on Tuesday

(C) 50 mCi 99mTc can be "milked" at 9 A.M. on Sunday

(D) the generator can no longer be used for 99mTc production

5.

The "ideal" radiopharmaceutical for imaging an organ in nuclear medicine studies would have

(A) a short half-life

(B) no particulate emissions

(C) rapid clearance from the blood stream

(D) photons with an energy of about 150 keV

(E) all of the above

6.

The radiation level adjacent to the one week-old 99Mo/99mTc generator depends on all of the following EXCEPT the

(A) initial activity of 99Mo

(B) number of times the generator was milked

(C) amount of Pb shielding around the generator

(D) amount of 99Mo remaining

(E) distance from the generator

7.  

Technetium-99m generators CANNOT be

(A) produced in a cyclotron

(B) used to dispense more than 1 Ci

(C) shipped by air

(D) purchased by licensed users

(E) used for more than 67 hours

8.  

Match the following half-lives with the appropriate radionuclide.

(A) 2 minutes

(B) 110 minutes

(C) 13 hours

(D) 67 hours

(E) 8 days

(i) Fluorine-18

(ii) Molybdenum-99

(iii) Iodine-123

(iv) Iodine-131

(v) Oxygen-15

9.  

Gamma camera crystals

(A) are made of cesium iodide

(B) convert 95% of gamma ray energy to light photons

(D) have lead backing to minimize backscatter

(E) have a high probability of absorbing 140 keV photons

10.  

The pulse height analyzer in a gamma camera system

(A) increases the detector efficiency

(B) analyzes the total energy deposited in crystal

(C) corrects the count rate losses due to "dead time"

(D) performs a coincidence detection analysis

(E) increases the count rate

11.  

 Match the typical resolution at full width half maximum (FWHM) with the detection system.

B.    Gamma camera (low-energy all-purpose collimator

C.    Gamma camera (high-resolution collimator)

D.    PET

(i) 3mm

(ii) 5mm

(iii) 7.5 mm

(iv) 10 mm

12.     

For each clinical application, match the best collimator.

(A) Thyroid imaging

(B) Pediatric study

(C) Lung scan

(D) Liver scan

(i) Diverging

(ii) Parallel hole

(iii) Converging

(iv) Pinhole

13.    

 For parallel hole collimators, which of the following improves as the distance from the face of the collimator is increased?

(A) Resolution

(B) Sensitivity

(C) Energy resolution

(D) Imaging time

(E) None of the above

14.       

Nuclear medicine images acquired using a computer typically have

(A) 500,000 to 1,000,000 counts

(B) matrix sizes of 64 x 64 or 128 x 128

(C) 256 gray scale levels

(D) 4 to 16 kBytes of image data

(E) all of the above

15.      

In general, gamma camera system resolution with a parallel-hole collimator

(A) is determined at full width half maximum (FWHM)

(B) includes an intrinsic resolution of about 3 mm

(C) depends on collimator sensitivity

(D) deteriorates with distance from the collimator

(E) all of the above

16.      

The system resolution of a gamma camera with a parallel hole collimator improves with increased collimator

(A) hole size

(B) thickness

(C) diameter

(D) distance to patient

(E) sensitivity

17.      

Thyroid imaging studies can be performed with all of the following EXCEPT

(A) 99mTc pertechnetate

(B) NaI uptake probe

(C) 123 I

(D) parallel hole collimator

(E) pinhole collimator

18.      

 A circular cold spot artifact in a gamma camera image could NOT be the result of

(A) a cracked NaI crystal

(B) a metallic object on the patient

(C) a defective photomultiplier tube

(D) an incorrect photopeak energy setting of the PHA

19.      

Match the following half-life relationships.

(A) Tb is very long

(B) Tb is very short

(C) Tb and T1/2 are equal

(D) Tb and T1/2 are both very long

(i) Negligible loss of activity

(ii) Te = Tb

(iii) Te = Tb/2

(iv) Te = T1/2

20.     

When 99mTc is administered to a patient, which of the following CANNOT contribute to the patient dose?

(A) Auger electrons

(B) Beta particles

(C) Internal conversion electrons

(D) Gamma rays

(E) Characteristic x-rays

21.       

Which of the following statements regarding radioiodine and the fetal thyroid are true?

(A) Inorganic iodine crosses the placenta

(B) Iodine can concentrate in fetal thyroids

(C) The highest risk is in the second and third trimesters

(D) Fetal thyroid is not present before week 10 of pregnancy

(E) All of the above

22.     

True (T) or False (F).

For patients undergoing typical nuclear medicine procedures

(A) effective dose equivalents are about 5 mSv (500 mrem)

(B) the dose is lower than a chest x-ray examination

(C) maximum organ doses are about 50 mGy (5 rad)

(D) the effective dose equivalents are similar to PET studies

(E) increasing the NM imaging time increases the dose

23.     

An ideal therapeutic radionuclide (e.g.32P) would have

(A) high uptake in the organ of interest

(B) high-energy beta decay

(C) no high-energy gamma rays

(D) a long biologic half-life in the organ of interest

(E) all of the above

24.     

Match the following image characteristics with the appropriate equipment.

(A)  Edge packing

(B)  Linearity

(C)  Uniformity

(D) Distortion

(i) Damaged collimator

(ii) Flood source

(iii) Line bar phantom

(iv) Periphery of gamma camera

25.       

Low-level radioactive wastes, such as tubing and swabs contaminated with 99mTc, may be monitored with

(A) Geiger-Muller counters

(B) film badge dosimeters

(C) thermoluminescent dosimeters

(D) ionization chambers

(E) do not need to be monitored

26.       

Match the radionuclide impurity with the corresponding radioactive material.

(A)  123I capsules

(B)  99mTc pertechnetate

(C)  67Ga

(D)  201Tl

(i) 99Mo

(ii) 124I

(iii) 202Tl

(iv) None

27.  

True (T) or False (F).

Single photon emission computed tomography (SPECT) normally requires

(A)  positron emitting radioisotopes

(B)  gamma camera rotation

(C)  coincidence detection

(D)  pulse height analysis

(E) filtered back projection reconstruction algorithms

(F) sampling of activity in patient's blood

28.  

For SPECT, all the following are true - EXCEPT

(A) 64 or 128 projections are obtained

(B)  it takes about 20 minutes to perform

(C)  corrections are usually made for patient motion

(D) images show relative radioisotope concentrations

(E) image quality is affected by scatter

29.  

Advantages of PET over conventional gamma camera imaging include

(A) a wider choice of molecules that may be labeled with positron emitters

(B) better resolution

(C) lower image noise

(D) rapid decay of radiopharmaceutical

(E) all of the above

30.  

PET imaging systems

(A) need high-energy parallel hole collimators

(B) cannot handle very high count rates

(C) suffer from significant attenuation losses

(D) detect annihilation photons in coincidence