ST:11 (Test 7) Flashcards
If a 20 mCi dose of 99mTc HDP are needed at 9am, how much activity should the syringe contain if the technologist prepares it at 7am? (2hr decay factor on chart is 1.259)
a. 26.7 mCi
b. 21.26 mCi
c. 25.18 mCi
d. 15.9 mCi
c. 25.18 mCi
Using table 2.1b determine the decay factor for 99mTc at 7 hours (chart displays 3hr DF= .707 and 4hr DF= .630)
a. 0.551
b. 1.337
c. 0.445
d. 0.432
c. 0.445
On Monday morning at 6am, a technologist is preparing a 99mTc ECD kit that is to be used for the SPECT brain scans at 8am,9am,10am. Each patient should receive 10mCi. What is the minimum activity that should be added to the kit during preparation?
a. 42.6 mCi
b. 52.0 mCi
c. 44.5 mCi
d. 30.0 mCi
a. 42.6 mCi
A chromatography strip is used to test a kit for radiopharmaceutical impurity and is counted in a well counter. Part A contains 99mTc pertechnetate, and Pat B contains bound 99mTc in the desired from. If the results show 258,000 cpm in Part B, and 55,000 cpm in Part A, can this kit be used for injection into patients?
a. No
b. Yes
a. No
A chromatography strip is used to test a kit for radiochemical impurity and is counted in a well counter. Part A contains 99mTc pertechnetate, and Pat B contains bound 99mTc in the desired from. If the results show 258,000 cpm in Part B, and 55,000 cpm in Part A, What is the approximate labeling efficiency for the kit?
a. 18%
b. 79%
c. 82%
d. 21%
c. 82%
A chromatography strip is used to test a kit for radiopharmaceutical impurity and is counted in a well counter. Part A contains 99mTc pertechnetate, and Pat B contains bound 99mTc in the desired from. If the results show 258,000 cpm in Part B, and 55,000 cpm in Part A, what is the approximate radiochemical impurity?
a. 79%
b. 82%
c. 21%
d. 18%
d. 18%
A vial of 99mTc eluate is tested for 99Mo breakthrough, and the amount of breakthrough is 25 uCi in 775mCi at 6am. Following the preparation of all kits to be used that day, 450 mCi of 99mTc is left. That night, a technologist is asked to perform a scrotal scan at 11pm. Must the generator be eluted again?
a. Yes, because the molybdenum breakthrough will now exceed the limit allowed by the NRC
b. No
c. Yes, because the amount of eluate will have decayed to below the amount needed for a patient dose
a. Yes, because the molybdenum breakthrough will now exceed the limit allowed by the NRC
A 99mTc MDP bone scan dose was prepared at 7am and contained 32 mCi/2 ml. At 9am, when the patient arrives, the technologist realizes that the patients age was overlooked (13 years). The technologist would now like to adjust the dose to 11 mCi. Given a 2 hr decay factor of 0.794, what volume should be discarded so that the correct dose remains in the syringe?
a. 1.13 ml
b. 1.5 ml
c. 0.87 ml
d. 0.65 ml
a. 1.13 ml
To reduce the possibility of pyrogenic reactions, all kits should be prepared using saline that contains bacteriostatic preservatives
a. False
b. True
a. False
While performing a GI bleeding study with labeled red blood cells, a technologist notices gastric activity that he suspects is the results of free pertechnetate. What could be done to support this suspicion?
a. Image the thyroid
b. Have the patient drink 2 glasses of water and empty his or her bladder
c. Narrow the window around the photopeak
d. Reimage the patient in the erect position
a. Image the thyroid
Convert 23 mCi to SI units
a. 850 MBq
b. None of the above
c. 850 GBq
d. 850 kBq
a. 850 MBq
23 mCi x 37 MBq/1 mCi=
If excessive aluminum is present in 99mTc eluate, which of the following would be expected on a bone scan?
a. Lung uptake
b. Liver uptake
c. Gastric uptake
d. Thyroid uptake
b. Liver uptake
Radiochemical impurities often result from
a. Introduction of water into the kit AND introduction of oxygen into the kit
b. Introduction of nitrogen into the kit
c. Introduction of water into the kit
d. All of the above
e. Introduction of oxygen into the kit
a. Introduction of water into the kit AND introduction of oxygen into the kit
Which of the following is the most effective means of measuring low levels of removable radiation?
a. With a pocket dosimeter
b. By performing an area survey
c. By performing a wipe test
d. With a TLD
c. By performing a wipe test
What is the dose rate limit at the package surface for a shipment of radioactive material bearing a Yellow III label?
a. 50 mR/hr
b. 200 rads
c. 200 mR/hr
d. 200 mrem
c. 200 mR/hr
Which of the following measures absorbed doses?
a. Millicurie
b. Gray
c. All of the above
d. Becquerel
b. Gray
If the dose rate at 3 meters from a radioactive source is 100 mrem/hr, what will the dose rate be at 6 meters?
a. 12.5 mR/hr
b. 25 mR/hr
c. 75 mR/hr
d. 50 mR/hr
b. 25 mR/hr
The philosophy of the ALARA program is to keep the radiation dose:
a. As low as reasonably achievable
b. As long as reasonably acceptable
c. As low as recently authorized
d. As long as reasonably attained
a. As low as reasonably achievable
All of the following are critical factors in keeping radiation exposure to a minimum except:
a. Time spent near the radioactive source
b. Distance from the source of radiation
c. Geometry of the container holding the source of radiation
d. Shielding of the radioactive source
c. Geometry of the container holding the source of radiation
Gaseous radio-pharmaceuticals may only be used in rooms that
a. Contain an oxygen supply
b. Have at least one window
c. Are at a negative pressure compared to surrounding rooms
d. Are at a positive pressure compared to surrounding rooms
c. Are at a negative pressure compared to surrounding rooms
If the exposure rate at 4 meters from a radioactive source is 5 mR/hr, what will the exposure rate be at 3 meters?
a. 6.5 mR/hr
b. 7.4 mR/hr
c. 2.8 mR/hr
d. 8.9 mR/hr
d. 8.9 mR/hr
If the exposure rate at 10 meters from a radioactive source is 15 mR/hr, what will the exposure rate be at 25 meters?
a. 6 mR/hr
b. 3 mR/hr
c. 10 mR/hr
d. 2.4 mR/hr
d. 2.4 mR/hr
A spill of 99mTc increases the exposure rate in a room from 1.7 mR/hr to 3.15 mR/hr. The room is posted with a sign reading “Caution-Radioactive Materials”. What would be the ideal solution?
a. Change the sign to one reading “Caution-Radiation Area”
b. Place absorbent paper over the spill and close the room until the activity has decayed
c. Decontaminate the floor with water and cleanser
d. Call the NRC
b. Place absorbent paper over the spill and close the room until the activity has decayed
A technologist has 500 mrem registered on his ring badge in one month. What should be done to decrease exposure in the future?
a. Use lead pigs and syringe shields when preparing radio-pharmaceuticals
b. Wear lead aprons
c. Have another technologist elute the generator
d. All of the above
a. Use lead pigs and syringe shields when preparing radio-pharmaceuticals
OSHA requires that personnel exposure records be provided to employees
a. Monthly
b. Quarterly
c. Annually
d. Biannually
c. Annually
A room containing a 57Co sheet source is posed with a sign reading “Caution-Radioactive Materials”. The exposure rate measured next to the source is 5.2 mR/hr. What should be done?
a. Change the sign to one reading “Caution- Radioactive Area”
b. Store the source in a leaded container
c. Monitor the length of time the technologist can work near the source
d. None of the above
b. Store the source in a leaded container
What part of an imaging system emits light when it has absorbed a photon?
a. Photomultiplier tube
b. Collimator
c. Pulse height analyzer
d. Scintillation crystal
d. Scintillation crystal
Most of the photons emitted from the radiopharmaceutical which has been administered to a patient:
a. Do not contribute to the final image
b. Are received by the sodium iodide crystal AND are converted to a voltage signal
c. Are received by the sodium iodide crystal
d. Do not contribute to the final image AND are received by the sodium iodide crystal
e. Are converted to a voltage signal
a. Do not contribute to the final image
To obtain high resolution images of a small organ, gland or joint which collimator will be most useful?
a. Flat field
b. Low energy parallel hole
c. Pinhole
d. Diverging
c. Pinhole
As septal length _____, septal penetration _____.
a. Decreases, increases
b. Decreases. Decreases
c. Increases, increases
d. Increases, decreases
e. Increases, decreases AND decreases, increases
e. Increases, decreases AND decreases, increases
Which of the following degrade images?
a. Photon scatter in the patient AND increased patient to detector distance
b. Septal penetration
c. Photon scatter in the patient
d. All of the above
e. Increased patient to detector distance
d. All of the above
A technologist covers the collimator (which is facing the ceiling) with absorbent paper and obtains a uniformity image using a liquid flood source with added 99mTc.
A round cold spot is seen on the image. Subsequently the technologist removes the collimator, turns the camera face down and obtains another image using a point source placed on the floor. This image appears uniform.
What is the most likely cause of the cold spot on the first image?
a. Decoupled photomultiplier tube
b. Collimator defect
c. Improper energy peaking
d. Subtle crystal crack
a. Decoupled photo-multiplier tube
If two photons strike a sodium iodide crystal at the same time what will occur?
a. The system will perceive only one event which will contain the summed energy of both photons
b. Both will be correctly perceived
c. None of the above
d. Neither event will trigger production of light
a. The system will perceive only one event which will contain the summed energy of both photons
The time after a crystal has absorbed a photon before it able to respond to another event is called:
a. Dead time
b. Count rate
c. Distortion
d. Sensitivity
a. Dead time
The Z component of the signal in the photo-multiplier tube will:
a. Be removed by the PMT
b. All of the above
c. Be recorded on the Count rate time
d. Be processed by the pulse height analyzer
d. Be processed by the pulse height analyzer
The purpose of the photo-multiplier tube is to:
a. To filter out photons which strike the crustal from oblique angles
b. Keep any of the electrical signal which resulted from scatter or background from contribution to the final image
c. To convert light into an electrical signal and to magnify that signal
d. To convert radioactivity into light
c. To convert light into an electrical signal and to magnify that signal
A camera with three pulse height analyzers will be most useful for imaging:
a. 67Ga
b. 67Ga AND 133Xe
c. 111In
d. 99mTc
e. 133Xe
a. 67Ga
A technologist has set a 15% symmetric window for a 140 keV photopeak. What will happen to a 158 keV signal?
a. It will be accepted by the pulse height analyzer
b. It will be rejected by the pulse height analyzer
b. It will be rejected by the pulse height analyzer
A typical energy spectrum of 99mTc from a patient contains a broad peak around 90-140keV that is not present on the energy spectrum from a point source of the same isotope. This represents:
a. Compton scatter
b. The iodine escape peak
c. Lead X-ray peak
d. The signal from 99mTc
a. Compton scatter
Image exposure time may be determined by:
a. A preset number of counts
b. A preset time
c. information density
d. All of the above
d. All of the above