ST:7 Flashcards
According to the NRC, survey meters must be calibrated _____ and following any repairs.
(a)semiannually (twice a year)
(b) biannually (every other year)
(c) monthly (once a month)
(d) yearly (once a year)
(e) quarterly (four times a year)
(d) Survey meters are calibrated annually to make sure that the instrument is performing within NRC regulation guidelines.
The difference between a direct radiation survey and a wipe check radiation survey is that:
(a)There is none.
(b) One is qualitative and one is not.
(c) One is quantitative and one is not.
(d) One breaks bonds and the other does not.
(e) One gives an instant reading and one does not.
(e) The direct radiation survey will give an instant reading, while the wipe check does not give an instant reading.
For an occupational worker who has received 14,000 mRem of exposure to the eyes in 1 year on his/her eye dose dosimeter, which course of action would be appropriate?
(a)Recommend eye chelation therapy.
(b) Review ALARA standards to reduce exposure because because s/he is close to exceeding their annual eye dose limit.
(c) Review ALARA standards to reduce exposure because s/he has exceeded his/her annual eye dose limit.
(d) Recommend s/he use leaded eyeglasses to reduce exposure.
(e) Recommend s/he use thyroid shields.
(b) An occupational radiation worker is allowed up to 15,000 mRem/yr dose to the eye. Since this worker is close to but not exceeding the yearly dose, a review of the ALARA concept and a dedicated reduction in eye exposure in the future is recommended.
A nuclear medicine department has an action level of 500 mRem per month whole-body exposure. If you were the NRC inspector, what would you recommend to this site?
(a)Reduce their action level to at least 410 mRem per month to be compliant with annual possible levels of exposure.
(b) Reduce their action level to at least 450 mRem per month to be in compliance with annual possible levels of exposure.
(c) Increase their action level to 5000 mRem per month
(d) Nothing, everything is fine
(e) Reduce their action level to at least 430 mRem per month to be compliant with annual possible levels of exposure.
(a) It is recommended that a radiation occupational worker who is using radiation stay under 410 mRem per month. This limit will keep the worker’s radiation levels within the NRC regulations of 5,000 mRem per year whole-body dose.
The allowed dose of ionizing radiation to a declared pregnant woman’s embryo/fetus is:
(a)10% of the standard occupational workers whole-body dose per year
(b) 1% of the standard occupational workers whole-body dose per year
(c) 20% of the standard yearly occupational dose for the gestation period
(d) 1% of the standard yearly occupational dose for the gestation period
(e) 10% of the standard yearly occupational dose for the gestation period
(e) It is recommended that women who are pregnant stay within or lower than 10% (500 mRem) of the regular occupational limit of 5,000 mRem/yr for the duration of the gestational period.
In doing a room survey, you discover that a therapy patient’s room has removable contamination above acceptable levels. What is the acceptable level?
(a)<367 Bq/100 cm^2
(b) <200 MBq/100 cm^2
(c) <12,000 Bq/100 cm^2
(d) <200 Bq/100 cm^2
(e) <15,000 Bq/100 cm^2
(a) To stay in compliance with NRC regulations, the room radiation levels must be below this level of removable contamination: <367 Bq/100cm^2 or 22,000 dpm/100cm^2
In calibrating your survey meter for your nuclear medicine department, you discover that is has a 12% error. What is your next course of action to remain in compliance with NRC regulations?
(a)Recommend that it be serviced.
(b) Throw it away.
(c) Replace the batteries.
(d) Use the survey meter as you normally would.
(e) Check the high-voltage power supply.
(d) It is all right to use a survey as long as it does not exceed +-20% of expected readings according to the NRC.
You suspect that a low-level B emitter has been spilled on a countertop. Which of the following survey techniques would be best?
(a)wipe-check with a SCA/MCA-type meter
(b) scintillation probe-type meter
(c) wipe-check with a G-M-type meter
(d) pancake probe G-M-type meter
(e) wipe-check with a pocket dosimeter
(a) Performing a wipe check with a SCA/MCA would be the best method because it is able to detect the low energies from the beta emitter.
An unrestricted nuclear medicine waiting room is on the other side of the wall from a hot lab. G-M meter readings in the hot lab read 50 mRem/hr. Readings on the other side of the wall in the waiting room read 25 mRem/hr. What is the minimum number HVLs of Pb required in the wall to bring the waiting room reading down into compliance with NRC regulations?
(a)4
(b) 2
(c) 5
(d) 1
(e) 3
(a) For unrestricted areas, it is recommended that the radiation level stay below 2 mRem/hr. Therefore, if the waiting room reads 25 mRem/hr, then 4 HVLs of Pb is needed to decrease the radiation to the acceptable level of 2 mRem/hr.
If a G-M meter has a scale of 1-5 mR/hr. If a deflection on the meter reads 4.5 and the meter is set on the X0.1 setting, what is the reading?
(a)40.5 mR/hr
(b) 4.5 mR/hr
(c) 0.45 mR/hr
(d) 0.045 mR/hr
(e) 45 mR/hr
(c) The reading determined by using the G-M meter was 4.5 mR/hr. However, it was measured on the X0.1 setting. Therefore, the initial reading of 4.5 mR/hr has to be multiplied by X0.1 to get the reading form the meter correctly.
In operating a G-M meter on a daily basis, what is the first thing you should always do?
(a)Use a check source to make sure the meter is working correctly.
(b) Set it to the most-sensitive scale/setting.
(c) Insert the batteries.
(d) Check the batteries.
(e) Set it to the least-sensitive scale/setting.
(d) It is always important to verify that the battery in the survey meter is working correctly to ensure proper detector response.
Form X of NRC Form 3 includes all of the following EXCEPT:
(a)The employer must abide by the state and federal regulations.
(b) The worker is required to become familiar with the regulations and operating procedures for the work engaged in.
(c) The worker must abide by the state and federal regulations.
(d) The employer will make available to the worker a copy of all applicable state and federal regulations, licenses, and operating procedures pertaining to the work.
(e) The employer is not required to post any notices of violations of the regulations involving radiological working conditions.
(e) According to the NRC, the employer is required to post any notices or violations of the regulations to employees.
The triblade radiation symbol must be which of the following colors on a yellow background?
(a)green
(b) red
(c) purple
(d) brown
(e) gray
(c) Radiation warning signs consist of a purple, magenta, or black tri-blade symbol on a yellow background.
Which of the following radiation signs would be required if a survey meter reading were 40 mRem/hr at 60 cm from a source in the room?
(a)”Caution: Radioactive Material”
(b) “Caution: High Radiation Area”
(c) “Caution: Radiation Area”
(d) “Grave Danger: Very High Radiation Area”
(e) “Caution: Very High Radiation Area”
(b) Different radiation caution signs are used depending on the amount of radiation an individual is likely to receive in that area in the course of 1 hr while 30 cm from a radioactive source or surface. Using the Inverse Square Law and the information given, it can be determined that an individual in this circumstance would receive 160 mRem/hr at a distance of 30 cm. For an area where an individual is exposed to radiation levels in excess of 100 mRem/hr, the correct sign to post is the “Caution: High Radiation Area” sign.
When a DOT II radioactive label on a package reads 9 mR/hr at 1 m, what is the appropriate action to take?
(a)Log in the package as you normally would.
(b) Contact the regional office of the NRC.
(c) Inform the vendor that the wrong label was on the container.
(d) Notify the DOT that a “shipment event” has occurred.
(e) Notify the DOT that a “medical event” has occurred.
(c) If a package reads 9 mRem/hr at 1 meter, it should have a DOT yellow III shipping label. A DOT Yellow II shipping label is limited to a reading of 1 mRem/hr at 1 m. When a package arrives with the wrong label, the vendor should be contacted. DOT I (white) At contact, not more than 0.5 mR/hr At 3 feet (1 m), no detectible radiation (NDR) DOT II (yellow) At contact, not more than 50 mR/hr At 3 feet (1 m), not more than 1 mR/hr DOT III (yellow) At contact, not more than 200 mR/hr At 3 feet (1 m), not more than 10 mR/hr
The average energy required to create an ion pair in air is _____.
(a)60 eV
(b) 34 eV
(c) 5 eV
(d) 30 keV
(e) 50 eV
(b) The average amount of energy required to cause an ionization depends on the type of gas used in the chamber, but it is generally between 20 and 45 eV per ion pair. 34 eV per ion pair is a commonly accepted value.
The ionization of the ENTIRE fixed volume of a gas due to secondary ionization is known as the _____:
(a)Geiger effect
(b) Townsend avalanche
(c) proportional effect
(d) internal amplification
(e) inverse gain
(a) Region V of gaseous detectors is the Geiger-Mueller region. Within this region, a charged particle, x-ray, or gamma ray will initiate an avalanche of ionization reactions (Townsend avalanche). When one initial ionization event triggers an Townsend avalanche of secondary ions that extends throughout the entire volume of the detector, this is called the Geiger effect.
How do the sizes of the pulses produced by the collection of ions in the proportional region compare to those produced by an instrument that operates in the ionization region of the gas curve for radiation detectors?
(a)The pulses are in resonance.
(b) The pulses are smaller.
(c) The pulses are the same size.
(d) The pulses are larger.
(e) The pulses are affected by pulse pile-up.
(d) The sizes of the pulses are determined by the amount of ions created in the gas chamber. More ions are created when there is a greater charge between the cathode and anode. On the characteristic voltage curve for gas detectors, the proportional region operates at a higher current than the ionization region. Because the proportional region operates at a higher current, it produces more ions and has a larger pulse.
Gas amplification is a phenomenon associated with instruments that operate in which region of the gas curve for radiation detectors?
(a)recombination
(b) ionization
(c) proportional
(d) continuous discharge
(e) G-M
(c) Within the proportional region of the characteristic voltage curve for gaseous detectors, charged particles collide with gas molecules to produce additional ionization events. This additional ionization results in an amplified current that is proportional to the number of original ion pairs created by the incident radiation. Because ions collide with gas to create an amplified current, this occurrence is called gas amplification.
The output pulse height of a gaseous detector is, in most cases, dependent upon what?
(a)the quantity of radiation that passes through the gas
(b) numbers of ions produced in the gas
(c) volume of gas in the detector
(d) pressure of the gas in the tube
(e) type of gas in the tube
(b) The pulse height represents the amount of radiation detected in the gas chamber. The amount of radioactivity is based upon the number of ions produced by the interactions between the gas and radiation.
Which of the following is used for SPECT system performance?
(a)high count flood
(b) COR offset measurement
(c) PLES phantom
(d) Jaszczak phantom
(e) 3D or 4D operation
(d) A Jaszczak phantom consists of a 20-cm-diameter plexiglass cylinder with rod and spheres inserted. The Jaszczak phantom provides excellent information about SPECT performance.
Which of the following operations would help in improving the image contrast AFTER display?
(a)use a smoothing filter
(b) use an edge enhancement filter
(c) use windowing
(d) use a formatter
(e) use a PHA
(c) Neither smoothing nor edge enhancement filters will improve image contrast after display . A formatter is no longer widely used in most facilities because it is for a gamma camera using film.
Which SPECT cardiac slice is used to generate a polar plot?
(a)transverse
(b) HLA
(c) VLA
(d) SA
(e) sagittal
(d) Polar plots are circular profiles of the heart created by placing the most-apical short axis slice in the center, surrounded by each successive short axis slice. The most-basal slice becomes the outermost ring of the plot.
For the majority of physiologic studies, “cold” spots are areas on the image display that indicate:
(a)necrotic tissue
(b) mistuned PMTs
(c) increased activity
(d) nonlinearity
(e) a cracked crystal
(a) Any area that uptakes the radiotracer will display as “hotter” than the background. This means that there is more uptake in these locations. Radiotracer will uptake in active cells and overactive cells. Cold spots are indicative of areas in which the cells are not active, such as dead or necrotic tissue.
Correction tables are used for:
(a)uniformity correction
(b) detector misalignment correction
(c) COR correction
(d) linearity correction
(e) spatial linearity correction
(a) Sometimes camera non-uniformity can be attributed to regional variations of insensitivity. Count subtraction/addition would be most appropriate at this point. Most gamma cameras achieve this by using an isotope- or collimator-specific uniformity correction map to generate an image of final non-uniformity within a +-1-3% range.
Total combined energy of the TWO annihilation photons originating from an annihilation reaction is:
(a)500 keV
(b) 1.02 MeV
(c) 1 MeV
(d) 511 keV
(e) 2.04 MeV
(b) A good event in PET is determined by the coincident detection of two 511-keV photons for a total of 1.02 MeV. These two 511-keV annihilation photons originate from the combination of a positron and an electron during the annihilation reaction.
The path between the two detectors in PET is referred to as the:
(a)line of origination
(b) line of action
(c) line of flight
(d) line of response
(e) line of correction
(d) In PET imaging, during coincidence detection, each crystal acts as a separate detector. Each scintillation crystal is allowed to be in coincidence with other scintillation crystals. Each pair of crystals for which coincidence is allowed is designated as an individual line of response.
The chance detection of photons from UNRELATED annihilation events within the coincidence timing window is called the _____ coincidence:
(a)true
(b) scatter
(c) prompt
(d) random
(e) delayed
(d) Random coincidence occurs when two photons from two separate annihilations are detected within the coincidence timing window. The system naturally assumes that both photons come form one annihilation event and that the interaction occurred within the line of response for both detectors.
A “blank scan” is performed in PET:
(a)hourly
(b) monthly
(c) weekly
(d) with every patient study
(e) daily
(e) A “blank scan” is a short-timed acquisition that is done at the beginning of each day to verify that the PET’s tomography feature is operating correctly for the day.
Upon performing a blank scan, your final image looks like this. (diagonal line artifact across the image) What is the likely explanation?
(a)perfect blank scan
(b) high voltage fluctuation
(c) detector malfunction
(d) unexplained phenomenon
(e) artifact in the field of view
(c) In PET tomography, since each block has a small number of photomultiplier tubes and uses only one set of electronic devices, a malfunction will oftentimes affect the entire sinogram. Therefore, since blocks typically appear as diagonal lines on the sinogram, a malfunction also appears along a diagonal line.
In nuclear medicine, “windowing” (choosing a linear scale with threshold) is used primarily for:
(a)background subtraction
(b) image normalization
(c) background normalization
(d) image reconstruction
(e) background addition
(c) The purpose of the window in reconstruction techniques is to limit the reconstruction to data within a range, much like a pulse height analyzer on a gamma camera. Thus, it is used primarily for background subtraction.
Which of the following is the correct method to calculate gall bladder (GB) ejection fraction?
(a)(net min GB cts - net max GB cts) / net min GB cts
(b) (net max GB cts - net min GB cts) x 100 / net min GB cts
(c) (net max GB cts - net min GB cts) / net max GB cts
(d) (net max GB cts) x 100 / (net max GB cts - net min GB cts)
(e) (net max GB cts - net min GB cts) x 100 / net max GB cts
(e) This is the only equation given that accurately represents the true total net value of counts from the gallbladder by using the percent difference equation. This equation can also be represented as:
(pre-CCK cts - lowest post - CCK cts) x 100 / pre-CCK cts
For SPECT acquisition, a reasonable choice for pixel size would be:
(a)5.25 mm^2
(b) 1/3 FWHM of detector resolution or smaller
(c) equal to 3 FWHM
(d) equal to 2 FWHM
(e) 3.12 mm^2
(e) If a test image of two point sources is acquired in a 128 x 128 image matrix, the approximate pixel size would be 3.133 mm in one plane. Both the x and y planes are needed.
The star artifact during SPECT reconstruction can be reduced by:
(a)increasing the time per projection
(b) increasing the number of projections
(c) applying a 4 D mode acquisition
(d) decreasing the number of projections
(e) decreasing the time per projection
(b) Unfiltered backprojection (UBP) is a method of reconstruction used in SPECT imaging. One disadvantage of unfiltered backprojection is that the area of increased count density is greater than the area of increased activity in the object. As more projections are added to the object, the image begins to form a star artifact, and the object’s size increases. The more projections are added, the larger and blurrier the star artifact becomes. This is why filtered backprojection is commonly used. With regular or filtered backprojection, since it is used clinically, the more projections you have, the better the resolution.
Which one of the following WILL NOT give information on left ventricular function?
(a)gated equilibrium radionuclide angiography
(b) gated myocardial perfusion imaging
(c) ungated first-pass study
(d) gated myocardial PET
(e) ungated myocardial SPECT
(e) The purpose of the first-pass study is to evaluate the ejection fraction of the right and/or left ventricle and determine the overall functioning capabilities of the heart. When calculating left ventricular ejection fraction, a multiple-gated acquisition is normally used. Gating slows heart motion and contraction to be resolved better by dividing the projections into discrete time intervals throughout an entire cardiac cycle. This provides more-precise and specific information related to a specific portion of the heart. this method includes gated equilibrium radionuclide angiography and gated tomographic myocardial perfusion imaging. A first-pass study occurs too quickly to get any reliable gating, but one does get ventricular function information. Therefore, ungated myocardial SPECT would not provide the information on ventricular function that all the other options here do.
When performing a thyroid uptake, the non-thyroidal body background measurement is obtained over the:
(a)stomach
(b) skull
(c) sternum
(d) thigh
(e) lumbar spine
(d) The thigh area is used to obtain non-thyroidal body background because it provides a more-accurate approximation of the soft tissue uptake throughout the entire body. The camera is positioned over the patient’s thigh at the same distance as it is positioned from the thyroid organ.
To prepare a patient for a thyroid uptake, the technologist performs a baseline thyroid count and measures radioactivity in the neck that is twice the background counts. Which of these actions is the most-appropriate for the technologist to follow?
(a)Cancel the exam: This is a contraindication for performing it in this patient.
(b) Administer [131I]sodium iodide instead of [123I]sodium iodide for the uptake.
(c) Put the patient on a low iodide diet.
(d) Subtract the baseline counts from the thyroid counts collected at a later time.
(e) Calculate a thyroid uptake using only the baseline counts.
(d) When preparing a patient for thyroid uptake using a thyroid probe, take counts from the thigh and neck (at thyroid level). The thigh counts represent background or baseline counts, Subtract the baseline counts from the actual thyroid counts as part of the calculation for uptake percentage.
The therapeutic effectiveness of 131I in treating hyperthyroidism results from the delivery of energy to thyroid tissue from:
(a)alpha particles
(b) neutron radiation
(c) y rays
(d) x-rays
(e) B particles
(e) X-ray alpha particles are not emitted from 131I. 131I is both a gamma and beta emitter; however, the beta particles are what is responsible for the effectiveness of the therapy.
Fever, dehydration, and slightly elevated white cell count are all symptoms of:
(a)nontoxic goiter
(b) euthyroid
(c) hypothyroidism
(d) benign thyroid goiter
(e) hyperthyroidism
(e) Some of the symptoms of hyperthyroidism include fever, sweating, dehydration, palpitations, increased heart rate, and elevated white blood cell counts.
In a normally functioning system, an increase in circulating thyroid hormone will cause TSH secretion to:
(a)remain the same
(b) increase
(c) decrease
(d) vary unpredictably
(e) cause a goiter formation
(c) An increase in thyroid hormone causes a decrease in the stimulation of TSH. Suppressed TSH is indicative of hyperthyroidism.
