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ST Questions > ST:4 > Flashcards

ST:4 Flashcards

1
Q 
A [99mTc]medronate image of the region shown (POSTERIOR PELVIS) would best demonstrate which of the following structures?
I. iliac crest
II. distal femur
III. ischium
IV. thoracic vertebrae 10-12
(a)III and IV only

(b) I and III only
(c) III only
(d) I, III, and IV only
(e) I, II, III, and IV

A

(c) The diagram depicts a posterior view of the lower lumber spine, the pelvis, and the proximal femurs. The iliac crests would be demonstrated on an anterior view of the pelvis. The distal femurs and the tenth through twelfth thoracic vertebrae are inferior and superior, respectively, to the structures shown in the diagram.

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2
Q

In performing a bone image, which of the following views would best demonstrate an abnormality in the calcaneous?
(a)lateral views of the patella

(b) post-void image of the pelvis
(c) posterior view of the distal humerus and radius
(d) anterior view of the distal humerus and radius
(e) plantar view of the feet

A

(e) The calcaneus-the heal of the foot-would be best imaged by placing the sole of the patient’s foot on the detector. Both feet may be imaged at the same time.

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3
Q

All of the following statements about 4-phase bone imaging are TRUE, EXCEPT:
(a)The study may be performed with any blood pool agent.

(b) This study includes both dynamic and static imaging.
(c) The patient is positioned under the camera before tracer administration.
(d) The third phase is performed 5-6 hr after tracer administration.
(e) The fourth phase is performed the next day.

A

(a) Because the second through fourth phases are performed to determine the presence of increased, persistent tracer uptake in the bone, the study must be performed with a bone agent.

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4
Q

Which of the following patients should receive fewer particles than typically administered for lung perfusion imaging?
(a)80-year-old woman with suspected pulmonary embolism

(b) 65-year-old man with chronic obstructive pulmonary disease
(c) 25-year-old woman with asthma
(d) 45-year-old man with right-to-left cardiac shunt
(e) 19-year-old women who is pregnant

A

(d) Patients with right-to-left cardiac shunts should be given a reduced number of particles because the particles pass through to the left side of the heart and into the systemic circulation, where they block capillaries and occlude blood flow in the brain, kidneys, heart, and other organs.

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5
Q

Which of the following statements about the wash-in/wash-out method for performing xenon ventilation studies is TRUE?
(a)The patient rebreathes a mixture of xenon and oxygen during the wash-in phase.

(b) The patient can be disconnected from the gas-trapping apparatus after the wash-in phase.
(c) This method is not recommended for comatose patients.
(d) It is not necessary to introduce oxygen or air into the xenon delivery system.
(e) The xenon system is a self-contained generator of xenon.

A

(a) In the wash-in/wash-out method, the patient breathes a mixture of xenon and oxygen for several minutes while a wash-in image is acquired. Air is then added to the system, and the xenon that is exhaled is trapped. Serial images are acquired as the xenon clears from the lungs. This method requires little cooperation from the patient; no breath-holding or deep breaths are required. therefore, the method is well-suited for comatose patients as well as for those on ventilators.

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6
Q

After the administration of [99mTc]pentetate aerosol with a face mask, radioactive contamination is likely to be found in all of the following areas EXCEPT:
(a)on the technologist’s hands

(b) around the patient’s mouth
(c) on the patient’s chest
(d) on the floor between the patient and nebulizer
(e) on the patient’s face

A

(a) there is aerosol leakage at the exhaust of the delivery system. the filter is unable to trap the exhausted aerosol sufficiently to prevent the escape of airborne tracer from the delivery system. The area around the patient’s mouth becomes contaminated when a face mask is used. Some of the airborne tracer is not inhaled and is deposited on the patient’s face.

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7
Q

Thyroid imaging may be performed with which of the following radiopharmaceuticals?
(a)[99mTc]pertechnetate

(b) [99mTc]sestamibi
(c) [99mTc]medronate
(d) [99mTc]pyrophosphate
(e) [99mTc]sulfur colloid

A

(a) For routine thyroid imaging, either [99mTc]pertechnetate or [123I]sodium iodide may be used. [99mTc]pertechnetate is trapped by the follicular cells of the thyroid. [123I]sodium iodide is trapped and organified (incorporated into the manufacture of thyroid hormones).

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8
Q

When performing a radioiodine thyroid uptake, nonthyroidal (body) background measurements may be taken over the:
(a)lateral skull

(b) mediastinum
(c) thigh
(d) abdomen
(e) substernal notch

A

(c) Nonthyroidal background measurements may be collected over the thigh. The uptake probe should be positioned vertically just above the patient’s knee to exclude bladder activity.

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9
Q

Pulse rates may be determined by all of the following methods EXCEPT:
(a)listening to the heart with a stethoscope

(b) using a pulse oximeter
(c) multiplying the respiration rate by 4
(d) analyzing the electrocardiogram
(e) using a 3-lead EKG

A

(c) In addition to the routine finger method of determining the radial pulse, pulse rates can be determined from the ECG or pulse oximeter. Listening to the heart with a stethoscope will give a pulse rate known as the apical pulse.

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10
Q

Which of the following statements regarding the administration of oxygen is FALSE?
(a)Oxygen is classified as a drug.

(b) With the consent of a physician or nurse, an oxygen appliance may be removed from the patient if it interferes with the imaging procedure.
(c) Oxygen therapy may be ordered by a physician, nurse, athletic trainer, or respiratory therapist.
(d) Orders for oxygen therapy must include the amount to be delivered, and the type of oxygen appliance to be used.
(e) Orders for oxygen therapy must include whether administration is to be continuous or intermittent.

A

(c) Because oxygen is a drug, it must be prescribed by a physician who specifies the amount to be received, the device to be used, and the time interval (continuous vs. intermittent). Cessation of oxygen therapy can be done only with the consent or supervision of a physician or attending nurse.

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11
Q

Treatment of the adverse effects induced by dipyridamole involves the administration of:
(a)aminophylline

(b) adenosine
(c) acetazolamide
(d) nitroglycerin
(e) aspirin

A

(a) Adverse effects of dipyridamole-a vasodilator-include hypotension, headache, and nausea. these effects may be reversed by administering aminophylline intravenously.

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12
Q

Which of the following must be discontinued for at least 24-36 hr before the administration of dipyridamole?
(a)water

(b) theophylline
(c) insulin
(d) Lasix
(e) aspirin

A

(b) When adenosine or dipyridamole is used for stress testing, the patient should be instructed to discontinue the use of certain substances that interfere with the action of these drugs. Caffeine and medications containing caffeine should not be consumed for at least 12 hr before testing. the use of xanthine derivatives (theophylline, aminophylline) should be discontinued for 24-36 hr before the nuclear medicine procedure. In a normal hepatobiliary study, the duodenum and proximal jejunum are visualized by 30 min after tracer administration.

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13
Q

In a normal hepatobiliary study, excretion of the tracer into the intestine should occur a maximum of how long after tracer administration?
(a)20-30 min

(b) 35-40 min
(c) 45-60 min
(d) 1-2 hr
(e) 2-3 hr

A

(a) In a normal hepatobiliary study, the duodenum and proximal jejunum are visualized by 30 min after tracer administration.

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14
Q

Which of the following agents would be used to perform a gallbladder ejection fraction?
(a)morphine and [99mTc]lidofenin

(b) sincalide and [99mTc]sulfur colloid
(c) sincalide and [99mTc]disofenin
(d) morphine and [99mTc]mertiatide
(e) sincalide and [99mTc]medronate

A

(c) A gallbladder ejection fraction is useful in assessing gallbladder dysfunction. In cases of delayed gallbladder visualization, sincalide is administered when the gallbladder is full. Pre- and postcontraction images are used to calculate an ejection fraction.

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15
Q

For which of the following procedures is the radiopharmaceutical administered orally?
(a)vesicoureteral reflux imaging

(b) gastrointestinal bleeding
(c) salivary gland imaging
(d) gastric emptying
(e) gallbladder ejection fraction determination

A

(d) For the determination of gastric emptying, the patient ingests the radiopharmaceutical. tracers to detect gastrointestinal bleeding and to image the salivary glands are administered intravenously. Depending on the method used, tracers to detect vesicoureteral reflux are instilled into the urinary bladder via a catheter (direct method) or injected intravenously (indirect method).

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16
Q

Patient preparation for functional renal imaging should include which of the following?
(a)hydration of the patient

(b) discontinuation of all medications
(c) fasting for at least 2 hr before imaging
(d) administration of furosemide 1 hr before imaging
(e) fasting for at least 4-6 hrs before imaging

A

(a) Renal function imaging should be performed with the patient in a normal state of hydration. To ensure hydration, the patient should drink 0.5 L of water 30-60 min before the study. False abnormal results may be obtained if the patient is not hydrated.

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17
Q

Static renal imaging is performed about how long after the administration of [99mTc]succimer?
(a)immediately

(b) 2 hr
(c) 4 hr
(d) 8 hr
(e) 6 hr

A

(b) [99mTc]succimer (DMSA) is used for static renal cortical imaging. Imaging is performed about 2 hr after tracer administration.

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18
Q

Patient preparation for [67Ga]citrate imaging may include administration of which of the following?
(a)diuretics

(b) potassium perchlorate
(c) Lugol’s solution
(d) adenosine
(e) laxatives

A

(e) [67Ga]citrate is excreted in the feces. The activity in the bowel may interfere with the interpretation of the study. Therefore, a bowel preparation may be prescribed at the time the tracer is administered.

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19
Q

A normal biodistribution of 111In-labeled leukocytes will demonstrate the greatest tracer uptake at 24 hr after injection in which of the following sites?
(a)bone marrow

(b) liver
(c) lung
(d) heart
(e) spleen

A

(e) At 24 hr after injection, a normal biodistribution of 111In-labeled leukocytes demonstrates tracer uptake only in the spleen, liver, and bone marrow. The greatest uptake is in the spleen, followed by the liver and the bone marrow.

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20
Q

A patient with diabetes who becomes hypoglycemic may exhibit all of the following signs and symptoms EXCEPT:
(a)weakness and shakiness

(b) confusion
(c) irritability
(d) nausea and vomiting
(e) low blood sugar

A

(d) Hypoglycemic patients may exhibit an intense hunger; might be weak and shaky; and may sweat excessively. They may become confused and irritable. Most patients will recognize symptoms before they become severe.

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21
Q

Which of the following tracers may be used to confirm brain death?
(a)[99mTc]oxidronate

(b) [99mTc]exametazime
(c) [99mTc]mertiatide
(d) [201Tl]thallous chloride
(e) [99mTc]medronate

A

(b) [99mTc]gluceptate, [99mTc]pertechnetate, or [99mTc]pentetate have been used to demonstrate brain death with a cerebral blood flow study followed by immediate static imaging. [99mTc]exametazime more recently has been used for this purpose. Because this tracer is normally concentrated in brain tissue in proportion to blood flow, it can visualized the degree of perfusion in the brain.

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22
Q

Counting cotton gauze that has been placed in a patient’s nose after intrathecal tracer administration is most useful when which of the following conditions is suspected?
(a)rhinorrhea

(b) hydrocephalus
(c) CSF shunt patency
(d) blockage of CSF flow
(e) pump patecy

A

(a) In the case of cerebral spinal fluid leaks through the nose (rhinorrhea) or ears (otorrhea), placing cotton gauze in the patient’s nose or ears is helpful in diagnosing such leaks. This technique is particularly useful with small leaks that may not be visualized on images.

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23
Q

Collodial [32P]chromic phosphate is administered by which of the following routes?
(a)intravenous

(b) intraperitoneal
(c) subcutaneous
(d) inhalation
(e) intrathecal

A

(b) Colloidal [32P]chromic phosphate is used to treat pleural or peritoneal effusions resulting from a malignancy. The agent is introduced directly into the pleural or peritoneal cavity. It should not be administered intravenously because it will be taken up in the liver, causing localized radiation damage.

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24
Q

Which of the following radiation safety measures should be used when performing 89Sr therapy?
(a)use of lead vial and syringe shields

(b) monitoring patient radiation levels daily
(c) use of absorbent paper in isolation room
(d) monitoring patient radiation levels weekly
(e) urinary catheterization for incontinent patients

A

(e) It is recommended that incontinent patients receiving [89Sr]chloride be catheterized to minimize the spread of contamination. Because 89Sr is primarily a beta emitter (less than 1% gamma emission), it is not necessary to place patients in isolation or monitor them with a survey meter. Lead shielding should not be used with this beta emitter because bremsstrahlung radiation will be produced in the shielding.

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25
On the basis of blood flow, which of the following is visualized as an area of high tracer concentration on a brain image performed with [99mTc]exametazime? (a)pineal body (b) white matter (c) gray matter (d) medulla oblongata (e) pituitary gland
(c) Uptake of SPECT brain agents is primarily in the gray matter of the cerebrum, which has a higher blood flow than white matter. These agents are localized in proportion to blood flow.
26
A technologist is performing a lung image on a patient known to have active tuberculosis. The most appropriate personal protective device the technologist should use it: (a)latex gloves (b) gown (c) lab coat (d) mask (e) booties
(d) The mask is the most appropriate for airborne respiratory diseases.
27
The patency of a LeVeen shunt may be demonstrated with which of the following radiopharmaceuticals? (a)[99mTc]disofenin or [99mTc]sulfur colloid (b) [99mTc]albumin or 99mTc-labeled red blood cells (c) [99mTc]pentetate or [99mTc]pertechnetate (d) [99mTc]MAA or [99mTc]sulfur colloid (e) [99mTc]medronate or [99mTc]sulfur colloid
(d) A LeVeen shunt is used to treat ascites by draining the excess fluid that accumulates in the peritoneal cavity into the superior vena cava. Sometimes the shunt tube becomes blocked. Radionuclide imaging is used to differentiate mechanical blockage of the tube from other reasons for increasing ascetic fluid. Imaging may be performed with either [99mTc]MAA or [99mTc]sulfur colloid. After the introduction of one of these tracers into the peritoneal cavity, images of the anterior abdomen (and chest if MAA is used) will demonstrate activity in the liver or lungs, confirming that the shunt is functioning. If the liver or lungs are not visualized, then the tubing is blocked.
28
Which of the following is common to imaging gastroesophageal reflux in both adults and children? (a)[99mTc]macro aggregated albumin is the tracer of choice. (b) The patient must fast starting at midnight before the test. (c) An abdominal binder is used to increase pressure over the abdomen. (d) The patient ingests dilute hydrochloric acid with the tracer. (e) [99mTc]Sulfur colloid is the tracer of choice.
(e) [99mTc]sulfur colloid is the radiopharmaceutical used to image gastroesophageal reflux in both adults and children. However, adults are administered a mixture of dilute hydrochloric acid, orange juice, and tracer after fasting from midnight. In infants and toddlers, the procedure is performed at the time of a scheduled feeding, so they may fast as little as 2 hr before receiving the tracer. In adults, an abdominal binder is used to increase external abdominal pressure to demonstrate more subtle instances of reflux. Because the abdominal muscles are important in pediatric respiration, the binder is typically not used with children, particularly infants.
29
The following studies are ordered for a patient: I. ERPF determination II. total-body bone imaging III. [111In]pentetreotide imaging In which order should the studies be performed so they do not interfere with one another and they can be accomplished in the shortest amount of time? (a)I, II, III (b) I, III, II (c) II, I, III (d) III, II, I (e) II, III, I
(a) In general, a quantitative study-any study whose results are a number-should be performed first, so radioactivity from another study does not interfere with or have to be accounted for when calculating the results of a quantitative study. An ERPF is performed with [99mTc]mertiatide. This radiopharmaceutical clears the kidneys quickly. Its 6-hr half-life is short enough to permit bone imaging the next day. [111In]pentetreotide imaging should be performed last. 111In has a three-day half-life, and the tracer may remain in the body for an extended period.
30
Which of the following is the common term for the artifact created by the presence of metals in the patient in CT imaging? (a)ringing (b) partial volume (c) arcing (d) biasing (e) streaking
(e) Patient-generated artifacts commonly come from patient motion, beam hardening, or metallic artifacts (commonly causing streak artifacts).
31
``` The region(s) of interest for detection of a left-to-right cardiac shunt is (are) drawn around which of the following structures? (a)superior vena cava ``` (b) one or both lungs (c) left ventricle (d) right ventricle and great vessels (e) aorta
(b) The region(s) of interest for detection of a left-to-right cardiac shunt is (are) drawn around one or both lungs to generate a pulmonary time-activity curve. The curve demonstrates the first pass of tracer through the lungs, as well as any tracer that has returned to the lungs and bypassed the systemic circulation.
32
Which of the following sets of vital sign measurements represent normal values for an adult? Pulse(bpm) - Blood pressure(mm Hg) - Respirations(resp/min) - Temperature(oral,F) (a)75 - 120/80 - 17 - 98.6 (b) 60 - 100/50 - 12 - 98.6 (c) 45 - 120/80 - 10 - 97 (d) 100 - 150/100 - 25 - 102 (e) 110 - 100/200 - 30 - 105
``` (a) The normal ranges of vital signs for adults are: Vital sign - Range Pulse - 60-100 beats per minute Blood pressure Diastolic 60-90 mm Hg Systolic 95-140 mm Hg Respirations 12-20 breaths/min Temperature 97.7-99.5F (36.5-37.5C) ```
33
A common antecubital vein used for intravenous administration of a radiopharmaceutical is the: (a)radial (b) cephalic (c) brachial (d) ulnar (e) plantar
(b) A variety of antecubital veins can be used for drug administration, but the two most commonly used are the basilica and cephalic veins.
34
The 51Cr red cell sequestration study is performed to identify abnormal destruction of red blood cells by the: (a)bone marrow (b) spleen (c) liver (d) heart (e) gallbladder
(b) The red cell sequestration study is performed to determine if the patient's anemia is the result of active splenic sequestration of normal red cells.
35
The difference in hematocrit values between the average whole-body hematocrit and the venous hematocrit is the result of: (a)variation in red blood cell diameter (b) difference in vessel size (c) increased amount of blood in the extremities (d) plasma leakage (e) difference in size of white blood cells
(b) Hematocrits vary with vessel size. Smaller vessels yield a lower hematocrit value than larger vessels.
36
``` On the basis of these counts per minute obtained from a thyroid uptake test: Thyroid: 2876 Patient background: 563 Standard: 10,111 Room background: 124 the percentage radioiodine uptake is: (a)3.5% ``` (b) 4.3% (c) 28% (d) 23% (e) 50%
(d) The formula for calculating thyroid radioiodine uptake is: % uptake = net thyroid cpm x 100 / net standard cpm Using the data, the percent uptake is: (2876 - 563 cpm) x 100 / (10,111 - 124 cpm) = 23%
37
A technologist is asked to check the flow rate on a drip infusion on a patient in the department. An acceptable flow rate is how many drops per minute? (a)1-5 (b) 75-100 (c) 40-60 (d) 10-20 (e) 100-125
(d) An acceptable flow rate for a drip infusion is 10-20 drops per minute. This rate may be adjusted by physician order.
38
The total blood volume may be calculated by dividing the measured red cell volume by the: (a)hematocrit (b) plasmacrit (c) number of red blood cells determined from a hemocytometer (d) corrected plasmacrit (e) corrected hematocrit
(e) The formula for calculating the total blood volume (TBV), based on the red cell volume, uses the corrected hematocrit (HCT) in the denominator. Correction is needed to account for trapped plasma and to adjust the venous hematocrit to an average whole body hematocrit. the formula is: TBV = red cell volume / (HCT x 0.91 x 0.97)
39
The following data were collected for a plasma volume determination: Net standard counts: 839,621 cpm Standard dilution factor: 15 Net plasma counts: 2,528 cpm/mL The calculated plasma volume in milliliters is: (a)2,214 (b) 3,321 (c) 4,516 (d) 4,982 (e) 5,280
(d) The formula for calculating plasma volume is: PV = (net standard cpm)(dilution factor) / (net plasma cpm/mL) From the data supplied: PV = (839,621 cpm)(15) / (2528) = 4982 mL
40
If the concentration of a 1:2,000 dilution is 0.05 uCi/mL, what is the tracer concentration of the original solution? (a)0.00025 uCi/mL (b) 10 uCi/mL (c) 25 uCi/mL (d) 100 uCi/mL (e) 125 uCi/mL
(d) A 1:2,000 dilution means that the concentration in the diluted solution is one 2,000th of the original concentration. In this problem, the concentration of the original solution is unknown. thus: (? uCi/mL) x 1/2000 = 0.05 uCi/mL 1/2000 = 0.05 uci/mL / x x = 2000(0.05 uCi/mL) = 100 uCi/mL
41
A patient scheduled for [18F]FDG imaging has a measured blood glucose level of 100 mg/dL. Which of the following actions should the technologist perform next? (a)Reschedule the patient for a later time. (b) Administer insulin to lower the patient's blood glucose level. (c) Administer glucose to raise the patient's blood glucose level. (d) Proceed with the examiniation. (e) Monitor the patient for hypoglycemia.
(d) In an adult, a normal fasting blood glucose level is 70-115 mg/dL. Because the patient's blood glucose level is within the normal range, the technologist can proceed with the examination.
42
Based on the net counts shown here, what is the percentage gallbladder ejection fraction? Maximum gallbladder counts: 185,632 Minimum gallbladder counts: 77,203 (a)71% (b) 41% (c) 58% (d) 29% (e) 13%
(c) % gallbladder ejection fraction: = (maximum GB counts - minimum GB counts) x 100 / maximum GB counts = (185,632 cts - 77,203 cts) x 100 / 185,632 cts =108,429 x 100 / 185,632 = 58%
43
After a 99Mo/99mTc generator is eluted, it takes approximately how many hours for the 99mTc activity to build up to a maximum level? (a)8 hr (b) 12 hr (c) 24 hr (d) 48 hr (e) 4 hr
(c) Maximum 99mTc activity is obtained about 24 hr after the last elution of 99mTc.
44
What is the total activity of 8 mL of 99mTc eluate that has a concentration of 2.0 MBq/mL? (a)16 MBq (b) 6 MBq (c) 32 MBq (d) 4 MBq (e) 10 MBq
(a) Concentration is expressed as activity per unit volume. In this instance: 2.0 MBq/mL = total activity / 8 mL total activity = 2.0 MBq/mL x 8 mL = 16 MBq
45
A wet column generator is equipped with all of the following parts EXCEPT a(n): (a)alumina column (b) lead shield (c) saline supply (d) collection port (e) charging port
(e) A wet-column generator is not equipped with a charging port because the saline supply is contained within the generator itself. A dry-column generator, however, uses a charging port to add saline to the column.
46
According to the USP, the maximum allowable aluminum concentration in 99mTc eluate is not to exceed: (a)0 ug/mL (b) 15 ug/mL (c) 20 ug/mL (d) 15 mg/mL (e) 10 ug/mL
(e) According to the USP, a 99mTc eluate should contain no more than 10 ug/mL of Al+3 in 1 mL of eluate.
47
Which of the following statements about determining 99Mo concentration in 99mTc eluate using the lead shield method is TRUE? (a)The eluate is assayed only for 99Mo. (b) The lead shield is used to absorb high-energy 99Mo photons. (c) The unshielded eluate is assayed for 99Mo and 99mTc by adjusting the dose calibrator settings. (d) The eluate in the lead shield is measured with the dose calibrator set to assay 99Mo. (e) The eluate is assayed only for 99mTc.
(d) The lead shield method of determining 99Mo contamination is based on the energy differences between 99mTc photons (140 keV) and 99Mo photons (740, 780 keV). The unshielded vial of eluate is placed into a dose calibrator set to assay 99mTc, and the 99mTc measurement is recorded. Then, the vial is placed into a lead shield designed to absorb the lower-energy photons of 99mTc but to permit transmission of the higher-energy photons of 99Mo. With the dose calibrator set to measure 99Mo, the shielded eluate is assayed for 99Mo, and the 99Mo measurement is recorded. The 99Mo concentration is calculated by making a ratio of the 99Mo and 99mTc measurements. Thus: uCi 99Mo / mCi 99mTc = uCi 99Mo/mCi 99mTc
48
The test kit used to measure aluminum ion concentration in 99mTc eluate contains specially treated indicator paper and an aluminum solution with a concentration of approximately: (a)2 ug/mL (b) 10 ug/mL (c) 5 ug/mL (d) 20 ug/mL (e) 15 ug/mL
(b) The test kit contains an aluminum solution with a concentration of approximately 10 ug/mL, the maximum aluminum ion concentration allowed in 99mTc eluate as established by the USP.
49
Which of the following pairs of radiopharmaceuticals may be used to perform lung perfusion and ventilation imaging? (a)[99mTc]sulfur colloid and [99mTc]pentetate aerosol (b) [99mTc]macroaggregated albumin and 133Xe gas (c) [99mTc]albumin and 133Xe gas (d) [99mTc]bicisate and [99mTc]pentetate aerosol (e) [99mTc]medronate and [99mTc]pentetate aerosol
(b) [99mTc]macroaggregated albumin is the tracer used for lung perfusion imaging. Lung ventilation imaging may be performed with 133Xe gas or [99mTc]pentetate aerosol. [99mTc]albumin remains in the blood pool and may be used for gated cardiac left ventricular function studies. [99mTc]sulfur colloid localizes in the reticuloendothelial system and may be used to image the liver, spleen, or bone marrow. [99mTc]bicisate is used to perform brain perfusion imaging.
50
An eluate of [99mTc]pertechnetate is assayed for 99Mo contamination at 0600 with the following results: 99Mo: 15.5 uCi 99mTc: 250 mCi At 1000, the eluate is used to prepare a 99mTc-labeled compound with a shelf-life of 8 hr. What is the latest time that the 99mTc compound may be administered to patients? (a)1400 (b) 1500 (c) 1700 (d) 1800 (e) 2400
(a) According to the NRC, the maximum allowable 99Mo concentration in a 99mTc eluate must not exceed 0.15 uCi 99Mo.mCi 99mTc at the time of administration to the patient. At 0600, the 99Mo contamination in the eluate is below the maximum allowable limit of 0.15 uCi 99Mo per mCi 99mTc: 15. 5 uCi 99Mo / 250 mCi 99mTc = 0.062 uCi 99Mo/mCi 99mTc After decay-correcting the 99Mo and 99mTc activities At 1400 14.2 uCi 99Mo / 99.5 mCi 99mTc = 0.143 uCi 99Mo/mCi 99mTc At 1500 14.0 uCi 99Mo / 88.7 mCi 99mTc = 0.158 uCi 99Mo/mCi 99mTc This level is above the maximum allowable limit of 99Mo contamination set by the NRC. Therefore, the eluate may not be administered to patients at or after 1400.
51
``` If the following reagents are available: Oxidronate kit Maximum 99mTc activity to be added: 250 mCi Reconstituting volume: 1-5 mL [99mTc]pertechnetate Concentration: 35mCi/mL Total volume: 10 mL what is the maximum amount of [99mTc]oxidronate (in mCi) that can be prepared from one kit? (a)175 mCi ``` (b) 225 mCi (c) 250 mCi (d) 350 mCi (e) 400 mCi
``` (a) 350 mCi of [99mTc]pertechnetate are available (35.0 mCi/mL x 10 mL = 350 mCi), but this amount exceeds the activity (250 mCi) and volume (5 mL) limits of the kit. Based on the maximum reconstituting volume (5.0 mL) of the kit, 175 mCi can be prepared: 35 mCi/mL x 5 mL = 175 mCi This activity (175 mCi) and volume (5 mL) are within the activity and volume limits for the kit. ```
52
Which of the following ingredients in a sulfur colloid kit are combined and heated? (a)[99mTc]pertechnetate and thiosulfate mixture (b) thiosulfate mixture and acid (c) [99mTc]pertechnetate, thiosulfate mixture, acid, and buffer (d) [99mTc]pertechnetate, thiosulfate mixture, and acid (e) thiosulfate mixture, acid, and buffer
(d) A sulfur colloid kit contains these reagents: acid, sodium thiosulfate, the material from which the colloidal particle is formed, and a buffer. To prepare [99mTc]sulfur colloid, [99mTc]pertechnetate, the acid, and the sodium thiosulfate mixture are combined in a sterile reaction vial and heated in a boiling-water bath. During boiling, sulfur particles are formed and condense, incorporating the 99mTc. After the boiled mixture is allowed to cool, the buffer is added to adjust the pH of the preparation.
53
When preparing to withdraw a unit dose of [32P]chromic phosphate, the technologist visually inspects the radiopharmaceutical and notes that it is a blue-green color. The technologist should next: (a)Contact the radiopharmaceutical manufacturer. (b) Reschedule the procedure. (c) Add it to a cup of water for dispensing to the patient. (d) Place the dose in radioactive waste for disposal. (e) Withdraw the unit dose.
(e) [32P]chromic phosphate is a blue-green color. Because this is the radiopharmaceutical's normal appearance, the technologist should continue preparing the unit dose.
54
What is the concentration of [99mTc]succimer if 1.5 mL succimer reagent and 30 mCi [99mTc]pertechnetate (concentration is 18 mCi/mL) and mixed to prepare the radiopharmaceuticals? (a)20 mCi/mL (b) 9.4 mCi/mL (c) 14.3 mCi/mL (d) 17.6 mCi/mL (e) 18 mCi/mL
(b) The concentration of the [99mTc]succimer is equal to the amount of radioactivity, divided by the volume of radioactivity and the volume of succimer reagent. The volume of [99mTc]pertechnetate required is: 99mTc activity required / [99mTc]pertechnetate concentration = 30 mCi / 18 mCi/mL = 1.7 mL The final concentration is equal to: 99mTc activity / (99mTc volume + succimer volume) = 30 mCi / (1.7 mL + 1.5 mL) = 9.4 mCi/mL
55
The tagging efficiency of a radiopharmaceutical is determined using these solvent/support media systems: Rf values Radiopharmaceutical - Free pertechnetate - Hydrolyzed-reduced 99mTc System 1 - 0.0 - 0.9 - 0.0 System 2 - 1.0 - 1.0 - 0.0 After chromatography strip containing a sample of the radiopharmaceutical was developed in each solvent, cut in half, and counted, these results were obtained: Counts per minute Solvent front half - Origin half System 1 - 1,716 cpm - 23,706 cpm System 2 - 21,001 cpm - 1,200 cpm What is the tagging efficiency of the sample? (a)92.8% (b) 6.7% (c) 12.1% (d) 87.9% (e) 5.4%
(d) Based on the Rf values, the free pertechnetate impurity is separated using system #1, and the hydrolyzed-reduced 99mTc impurity by using system #2. Therefore, the percentage of each impurity in the preparation can be determined directly: % free pertechnetate = 1716 cpm x 100 / (1716 cpm + 23,706 cpm) = 6.7% % HR-99mTc = 1200 cpm x 100 / (1200 cpm + 21,001 cpm) = 5.4% The tagging efficieny, or radiochemical purity of the sample is: 100% - (% free pertechnetate + % HR-99mTc) = 100% - (6.7% + 5.4%) = 100% - 12.1% = 87.9%
56
The label on an unopened vial states that the vial contains 10 mL of radiopharmaceutical with a concentration of 55.5 MBq/mL. When the technologist assays the vial in a dose calibrator, it measures 9 mCi. Which of the following actions should the technologist perform first? (a)Begin to prepare unit doses from the vial. (b) Check the radionuclide setting on the dose calibrator. (c) Perform an accuracy check on the dose calibrator. (d) Contact the radiopharmaceutical manufacturer. (e) Return the vial to the vendor.
(b) The technologist did not verify the label information and, therefore, should not withdraw any activity from the vial. According to the label information, the vial should contain a total activity of 555 MBq (10 mL x 55.5 MBq/mL), or 15 mCi: 555 MBq x 37 MBq/mCi = 15 mCi The technologist should first ascertain that the vial was assayed on the correct radionuclide setting on the dose calibrator. If the radionuclide setting was correctly placed, the technologist should next perform dose calibrator quality control. Only when the technologist has verified that the equipment was used properly and is functioning properly should the manufacturer be contacted.
57
A vial of [67Ga]gallium citrate is calibrated to contain 5 mCi at 0600, Pacific Standard Time, on March 8. How much activity does that vial contain on March 9 at 1200 Eastern Standard Time? (a)3.9 mCi (b) 4.9 mCi (c) 6.3 mCi (d) 3.7 mCi (e) 2.5 mCi
(a) The easiest approach is to first equate the calibration time to EST. (Most telephone company directories include a map of the time zones in the United States.) There is a 3-hr time difference between the East and West coasts, with the West Coast (Pacific Standard Time) being 3 hr earlier than the East Cost (Eastern Standard Time), thus: 0600 PST = 0900 EST Once this conversion is performed, the problem is a straightforward decay-correction problem. The elapsed time between 0900 EST on March 8 and 1200 EST (noon) on March 9 is 27 hr. From a decay factor table for 67Ga, the decay factor for 27 hr is 0.787. the total activity is decay-corrected for 27 hr to determine the total activity at 1200 EST on March 9: A(t) = A(0) x D = 5 mCi x 0.787 = 3.9 mCi
58
What is the average CT number for the lung in Hounsfield Units (HU)? (a)-1000 (b) -500 (c) -100 (d) -50 (e) zero
(b) The average CT number value for lung tissue is about - 500 HU. this value may vary with the beam quality of the CT scanner.
59
In labeling red blood cells with [51Cr]sodium chromate, which of the following components is first added to the ACD solution? (a)blood sample (b) [51Cr]sodium chromate (c) ascorbic acid (d) heparin (e) sodium chloride
(a) The patient's blood should be added to the ACD solution BEFORE 51Cr is introduced into the vial. Dextrose contained in the ACD solution chemically reduced the hexavalent 51Cr to a trivalent state, which prevents red cell tagging. In a trivalent state, 51 Cr cannot penetrate the red cell membrane.
60
All of the following are advantages of the in vitro method of labeling red blood cells with [99mTc]pertechnetate EXCEPT: (a)The red blood cells can be washed to remove substances from the plasma that may interfere with labeling. (b) A commercially manufactured kit that requires no cell separation by centrifugation is available. (c) Higher labeling efficiencies than with the in vivo method are possible. (d) In vitro labeling has the lowest risk of red cell hemolysis. (e) In vitro labeling allows clear separation from white blood cells.
(d) the in vitro method is recommended when patients are taking certain drugs, such as penicillin or doxorubicin, that have been shown to interfere with red cell labeling. In this method, the red cells can be washed and the interfering substances removed before cell labeling is attempted. The commercially prepared kit eliminates the need for centrifugation with the addition of reagents that oxidize or bind any stannous ion that has not been taken into the red cells, thus localizing the 99mTc uptake to the cells. Labeling efficiencies of 95% or greater have been reported for the in vitro method. Labeling efficiencies for the in vivo method are reported to be 80%-90% and for the modified in vivo method to be comparable with those of the in vitro method. Because the red blood cells are removed, labeled, and then reinjected, the risk of hemolysis of the red cells is greater with the in vitro method than with the other methods.
61
Which of this equipment is needed to verify the size and number of MAA particles in a [99mTc]MAA preparation? (a)dose calibrator (b) limulus amebocyte lysate solution (c) chromatography strips, solvent, developing chamber (d) hemocytometer, light microscope (e) G-M meter
(d) Particles are viewed with the aid of a microscope. their size and number can be determined by using the grids on the hemocytometer as a reference.
62
According to NRC regulations, records of patient dosage determinations must be retained for how long? (a)7 years (b) 5 years (c) 10 years (d) indefinitely (e) 3 years
(e) The NRC requires that patient unit dosage records be retained for 3 years.
63
During red blood cell labeling with 51Cr, the purpose of adding ascorbic acid to the ACD (acid-citrate-dextrose)-whole blood solution is to: (a)Reduce the chromate ion to a lower valence state. (b) Maintain the pH of the mixture. (c) Prevent clot formation. (d) Prevent hemolysis of the red blood cells. (e) Oxidize the chromate ion to a higher valence state.
(a) Ascorbic acid acts as a reducing agent to change the valence of radiochromium form +6 to +3, which stops the labeling process.
64
Upon visual inspection, a vial of [99mTc]MAA has a white, slightly cloudy appearance. Which of the following actions should the technologist perform next? (a)Prepare another vial of [99mTc]MAA. (b) Prepare unit doses from the vial. (c) Filter the preparation. (d) Adjust the pH of the preparation. (e) Add appropriate diluent.
(b) [99mTc]macroaggregated albumin is made up of aggregated protein particles (albumin). It normally appears as a cloudy, milky solution. Therefore, the technologist should use the vial to prepare unit doses.
65
On the basis of the chromatography results shown here, what is the percentage radiochemical purity of the [99mTc]mertiatide preparation? Origin - Solvent front System 1 - 107.5 uCi 99mTc mertiatide + HR-Tc - 9.2 uCi [99mTc]pertechnetate System 2 - 8.4 uCi HR-Tc - 132.6 uCi [99mTc]mertiatide +HR-Tc (a)13.9% (b) 96.2% (c) 92.1% (d) 94.0% (e) 86.1%
(e) The free pertechnetate impurity is separated using system #1, and the hydrolyzed-reduced 99mTc impurity by using system #2. Therefore, the percentage of each impurity in the preparation can be determined directly: % free pertechnetate = 9.2 uCi x 100 / (107.5 uCi + 9.2 uCi) = 7.9% % HR-99mTc = 8.4 uCi x 100 / (132.6 uCi + 8.4 uCi) = 6.0% The radiochemical purity of the sample is: 100% - (% free pertechnetate + % HR-99mTc) = 100% - (7.9% + 6.9%) = 100% - 13.9% = 86.1%
66
If an MAA kit contains approximately 6 million particles, what reconstituting volume is required to obtain 500,000 particles in 0.4 mL? (a)0.03 mL (b) 0.21 mL (c) 4.8 mL (d) 12 mL (e) 16 mL
(c) A proportion can be used to determine the total volume needed to reconstitute the MAA kit: particles in kit / total volume in kit = particles in patient dosage / volume of patient dosage 6 million particles / x = 500,000 particles / 0.4 mL x = 0.4 mL x 6 million particles / 500,000 particles = 4.8 mL
67
When assembling a needle and syringe for an intravenous administration, all of the following areas must remain sterile EXCEPT the: (a)luer lock (b) syringe tip (c) needle shaft (d) needle tip (e) outer side of the syringe barrel
(e) The areas of a needle and syringe that must remain sterile are any areas that will come into contact with the sterile solution being withdrawn into the syringe or any part of the needle that will be introduced into the patient.
68
The NRC defines an unrestricted area as one in which an individual will receive less than how many milliRems in an hour? (a)2 mRem (b) 5 mRem (c) 50 mRem (d) 100 mRem (e) 500 mRem
(a) According to the NRC, an unrestricted area is one in which access is not limited by or under control of a licensee and one in which an individual will receive less than 2 mRem in any hour.
69
A package containing radioactive material is monitored and found to produce 0.4 mR/hr at the surface and no detectable radiation exposure at 1 m from the surface. Which DOT label must be affixed to the outside of the package? (a)"Category I-A" (b) "Category II" (c) "Category III" (d) No DOT label is required. (e) "Category I"
``` (e) The label types and exposure rate limits for packages containing radioactive materials are: Label category - At surface (mR/hr) - At 1 m (mR/hr) Category I (white) - <=0.5 - No detectable radiation Category II (yellow) - <=50 - <=1.0 Category III (yellow) - <=200 - <=10 ```
70
The NRC requires that all of the following information be included in unit dosage measurement records EXCEPT the: (a)date of measurement (b) time of measurement (c) patient's name (d) radiopharmaceutical name (e) dose calibrator make and model number
(e) According to the NRC, dosage measurement records must include the radiopharmaceutical, the patient's name of identification number (if one assigned), the prescribed dosage, the determined dosage (or notation that the dosage is less than 30 uCi or 1.1 MBq), the date and time of the measurement, and the name of the person who measured the dosage.
71
If the distance between a radiation point source and a survey meter is doubled, the measured radiation exposure rate is reduced: (a)to half of the original exposure rate (b) unpredictably (c) to one-eighth of the original exposure rate (d) to one-quarter of the original exposure rate (e) to one-ninth of the original exposure rate
(d) The inverse square law states that doubling the distance from a point source reduces the radiation intensity to one-fourth of the original intensity.
72
According to NRC regulations, which of the following radiopharmaceutical administration errors must be reported to the NRC? (a)A patient receives 18 mCi of [99mTc]pertechnetate when 20-25 mCi was prescribed. (b) A patient scheduled for bone imaging receives 20 mCi of [99mTc]pertechnetate instead of [99mTc]medronate. (c) Patient A receives a hepatobiliary scan dosage intended for patient B. (d) A patient receives a whole-body scan dosage of 131I instead of 123I for a thyroid uptake and scan. (e) Patient A receives a bone scan dosage intended for patient B.
(d) A licensee must notify the NRC of medical events, which are defined as an administration of a licensed material that results in an effective dose equivalent (EDE) greater than 5 Rem, dose to an organ or tissue greater than 50 Rem, or shallow dose equivalent (SDE) to the skin greater than 50 Rem because of any of the following: The total dosage delivered differs from the prescribed dosage by 20% or more. The total dosage falls outside the prescribed range. The wrong radioactive drug was administered. The radioactive drug was administered by the wrong route. The radioactive dosage was administered to the wrong person. Of the possible answers to this question, only the 131I will result in a radiation exposure meeting these criteria. In addition, the incorrect radioactive drug was given. Even though options a, b, and c describe errors in the administration of a radiopharmaceutical, the exposure to the patient dose not exceed the criteria, and the error does not have to be reported to the NRC.
73
According to the NRC, a written directive for the administration of [89Sr]chloride must include all of the following information EXCEPT: (a)patient's Social Security number (b) radiopharmaceutical name (c) route of administration (d) signature of an authorized user (e) patient's name
(a) A written directive for administration of a therapeutic dosage other than [131I]sodium iodide must include the patient's name, the radioactive drug, the route of administration, and the dosage to be administered. It must be dated and signed by the authorized user before the dosage is administered.
74
According to the NRC, the radiation dose to the fetus of a declared pregnant worker must not exceed how many Rems during the pregnancy? (a)0.5 Rem (b) 50 Rem (c) 5 Rem (d) 500 Rem (e) 2 Rem
(a) According to NRC regulations, the radiation dose to the fetus of a declared pregnant worker must not exceed 0.5 Rem (500 mRem) during the entire pregnancy.
75
Which of the following monitoring techniques should be employed to rule out internal contamination after handling a radioiodine solution? (a)thyroid uptake 24 hr after handling the solution (b) urine counts 2-4 hr after handling the solution (c) plasma counts 24 hr after handling the solution (d) pocket dosimeter reading (e) G-M meter reading
(a) Iodine is taken up into the thyroid gland whether it is ingested, inhaled, or absorbed through the skin. Therefore, using an uptake probe to measure radioiodine uptake the day after handling a radioiodine solution is the method of choice.
76
When surveying for contamination, which of the following diagrams depicts the correct position of the probe of an end-window G-M meter in relation to the surface being monitored? (a)tilted (b) 1/2" away (c) directly on the surface (d) 6" away
(c) The flat end-window of a G-M meter is the area sensitive to radiation. Therefore, when surveying for surface contamination, the end of the probe should be placed directly over the area being surveyed. To avoid contaminating the probe, the probe should not touch the surface and should be kept approximately 1.5 inch from the surface.
77
According to the NRC, packages with which of the following DOT labels must be checked for contamination using a wipe test? (a)yellow II only (b) white I and yellow II only (c) yellow II and yellow III only (d) yellow III only (e) white I, yellow II, and yellow III
(e) According to the NRC, all shipments of radioactive materials identified with DOT radioactive labels of White I, Yellow II, or Yellow III must be tested for contamination using a wipe test.
78
The first step in the radioactive decontamination of personnel is to: (a)Immediately place the contaminated person in a shower. (b) Wash contaminated areas of the skin with soap and water. (c) Remove the contaminated person from the site of the spill. (d) Remove any articles of contaminated personal or protective clothing. (e) Establish hot and cold zones.
(d) Most contamination may be eliminated by removing personal clothing or protective garb, such as gloves or lab coats. Once contaminated clothing is removed, decontamination of skin surfaces should begin.
79
According to NRC regulations, a written directive must be retained: (a)for 1 year (b) indefinitely (c) for 5 years (d) for 3 years (e) for 7 years
(d) According to the NRC, written directives must be retained for 3 years.
80
According to the NRC, patient dosage records must be retained for how many years? (a)3 year (b) 1 years (c) 5 years (d) as long as the facility's license is in effect (e) 7 years
(a) According to the NRC, patient dosage records must be retained for 3 years.
81
If a technologist stands next to a radioactive source that is producing an exposure rate of 0.5 mRem/hr for 20 min, what radiation dose does the technologist receive? (a)17 mRem (b) 0.5 mRem (c) 10 mRem (d) 0.17 mRem (e) 23 mRem
(d) To determine the total dose, multiply the exposure rate by the time of exposure. In this case, the exposure rate must be converted from mRem/hr to mRem/min by dividing the hourly rate by 60 min: (0. 5 mRem/hr / 60 min/hr) x 20 min = 0.17 mRem
82
A wipe test gives a reading of 1240 cpm with a background count of 410 cpm. If the efficiency of the instrument is 35%, what is the wipe test reading in dpm? (a)35 dpm (b) 290 dpm (c) 3,542 dpm (d) 2,371 dpm (e) 5,273 dpm
(d) To determine wipe test reading in dpm: dpm = (gross cpm - background cpm) / decimal efficiency In this example: (1240 cpm - 410 cpm) / 0.35 = 2371 dpm
83
10 millisieverts is equivalent to how many milliRems? (a)0.1 (b) 1,000 (c) 100 (d) 1 (e) 10,000
(b) 1 mSv = 100 mRem; therefore, 10 x 100 mRem = 1000 mRem
84
If a technologist receives dosimeter readings that are nearly equal to the NRC limits, which of the following is the most appropriate action? (a)The technologist must cease working in a radiation area. (b) The technologist can work in a radiation area but must limit exposure. (c) The RSO must reassign the technologist to non-radiation exposure work areas. (d) The RSO must give the technologist a written warning. (e) The RSO must review the technologist's work habits.
(e) If an occupationally exposed worker ahs an exposure reading that approaches the NRC limits, the RSO is required to review the individual's work habits to determine what changes can be made to decrease exposure.
85
How often must dose-calibrator constancy be performed? (a)daily (b) monthly (c) weekly (d) annually (e) hourly
(a) The NRC requires that dose calibrators be tested for proper functioning according to nationally recognized standards. The standard of practice includes testing constancy on daily basis before the instrument is used to measure radiopharamceuticals.
86
According to the NRC, records of survey meter calibration are retained for how long? (a)7 years (b) 5 years (c) as long as the instrument is in use (d) as long as the facility license is in effect (e) 3 years
(e) The NRC requires that survey meter calibration records be retained for 3 years. It does not require records for daily constancy tests.
87
The y-ray spectrum shown here was obtained at a voltage of 800. (window is far to the right of the graph) To move the photopeak into the window, which of the following actions should be taken? (a)The voltage should be decreased. (b) The voltage should be increased. (c) The window should be widened. (d) The window should be moved. (e) The high voltage should be turned off.
(b) As voltage increase, the gamma ray spectrum moves to the right. Therefore, increasing the voltage will shift the photopeak toward the window and, if the voltage is increased sufficiently, into the window.
88
These are results of energy-resolution tests for the last four quarters: Month - % Energy resolution January - 9.5% April - 10.3% July - 10.9% October - 11.1% According to the data, which of the following statements is TRUE? (a)The energy resolution of the instrument is improving. (b) The test is erroneous. (c) The results indicate that the instrument should no longer be used. (d) The test should be performed with a different radionuclide. (e) The energy resolution of the instrument is worsening.
(e) As the percent energy resolution increases (the value becomes larger), the energy resolution worsens. this means that the FWHM is becoming larger because the photopeak is broadening and, hence, degrading the energy resolution of the instrument. The energy resolution of any counting system decreases with age as a result of deterioration of both the crystal and the electronics. sudden changes in energy resolution may indicate a racked crystal.
89
According to the NRC, how often must survey meters be calibrated? (a)daily (b) before each use (c) annually (d) monthly (e) bi-annually
(c) According to NRC regulations, survey meters must be calibrated before first use, annually, and after each repair.
90
On the basis of this flood image: (one side is colder than the other) which of the following should the technologist do? (a)Reacquire the flood for more counts. (b) There is non-uniformity; troubleshoot the problem. (c) Arrange for service immediately. (d) Perform Chi-square test. (e) There is uniformity; use as usual.
(b) This flood demonstrates significant non-uniformity. Therefore, the technologist should first confirm that the image was acquired on the correct radionuclide and window settings. A repeat image should be acquired if the settings were incorrect. If the repeat image also shows the non-uniformity, service should be requested. Patient studies must not be acquired on this instrument until the problem is corrected.
91
The standard of practice dictates that the center of rotation (COR) offset correction be performed how frequently on SPECT cameras? (a)weekly (b) daily (c) monthly (d) quarterly (e) hourly
(a) It is recommended that the COR offset correction be performed at least weekly.
92
How often should a uniformity flood be acquired on a scintillation camera? (a)weekly (b) daily (c) monthly (d) quarterly (e) hourly
(b) The standard of practice calls for acquisition of a uniformity flood every day the camera is used, prior to performing patient studies.
93
Static frame mode acquisition is the most appropriate type of image acquisition for which of the following procedures? (a)first phase of a three-phase bone scan (b) thyroid imaging (c) left ventricular ejection fraction determination (d) renal function imaging (e) bone imaging
(b) A static acquisition is performed in studies where the radiopharmaceutical localizes and remains in the area of interest for a period of time long enough for imaging to be completed. The radiopharmaceutical is fixed in the area of interest during the acquisition. For example, the thyroid is imaged after sufficient time has passed for the tracer to be localized in the gland. Data are acquired either for a preset number of counts or for a preset time. Dynamic frame mode acquisitions are used in studies where movement of the tracer is important to document. The blood flow phase (first phase) of a three-phase bone scan and renal function studies are examples of dynamic frame mode acquisitions. A left ventricle ejection fraction (LVEF) determination uses a gated technique, which is a variation of a dynamic acquisition.
94
Which of the following radionuclide sources is used to acquire an extrinsic uniformity flood? (a)99mTc point source with collimator removed (b) 57Co sheet source with collimator removed (c) 99mTc point source with collimator in place (d) 131I point source with collimator removed (e) 57Co sheet source with collimator in place
(e) The collimator must be in place when uniformity correction acquisitions are performed because collimators have inherent variations that differ from one collimator to another. Because an extrinsic flood is being acquired, a sheet source is required. A point source imaged with a collimator cannot distribute photons evenly over the crystal.
95
It is recommended that high-count uniformity correction flood maps be acquired how frequently? (a)daily (b) weekly (c) monthly (d) quarterly (e) hourly
(b) For uniformity correction maps, it is recommended that high-count flood images be acquired weekly. These flood images should not be confused with daily uniformity flood images that are acquired to check detector response.
96
Which of the following will increase the resolution of a "spot view" bone image obtained with a parallel-hole collimator? (a)moving the camera closer to the patient's body (b) increasing the pulse-height analyzer window width (c) using a high-sensitivity collimator instead of LEAP collimator (d) using fewer shades of gray to display the image (e) using a slant hole collimator
(a) The resolution of a parallel-hole collimator is greatest at its surface, so the closer the collimator is to the patient, the better the resolution will be. Increasing the window width will admit more scatter, decreasing the resolution. A high-sensitivity collimator has larger holes that admit photons that are traveling at greater angles. This decreases resolution, because the data are recorded as if the photon traveled on a straight line directly up from its origin to the crystal. If the number of shades of gray in the grayscale is decreased, there will be less detail and, therefore, less resolution.
97
If a Butterworth filter is applied to an image and the order of the filter remains constant, which of the following cutoff frequencies (the frequency at which the filter magnitude drops below 0.5) will result in the smoothest image? (a)0.50 cycles/pixel (b) 0.42 cycles/pixel (c) 0.33 cycles/pixel (d) 0.15 cycles/pixel (e) 0.12 cycles/pixel
(e) The lower the cutoff frequency, the more high frequencies (which provide image detail) are removed from an a image. Therefore, a cutoff frequency of 0.5 cycles/pixel results in an image with the most detail and the most high-frequency noise. At the other extreme, a cutoff frequency of 0.12 cycles/pixel removes many of the high frequencies, resulting in a very smooth image without much detail.
98
When a high activity of a radionuclide is used for a PET scan, image quality is degraded because: (a)deadtime decreases (b) random events increase (c) attenuation increases (d) noise increases (e) specificity decreases
(b) As activity increases, so does the number of events. With a large number of events occurring almost simultaneously, there is a greater likelihood that unrelated photons (randoms) will be mistaken as coincident pairs. Deadtime remains the same, but more events occur within that time frame and, therefore, go uncounted. Attenuation is not dependent upon activity; it is present regardless of the amount of activity administered. However, with a higher activity, more "good" events are going to be registered because more of them occur. Noise decrease with an increase in activity because, as the number of events increases, the effect of randomness (noise) decreases.
99
If a 20% window is set around a centerline of 364 keV, what energies will be accepted by the pulse-height analyzer? (a)291-437 keV (b) 328-400 keV (c) 344-384 keV (d) 354-374 keV (e) 364-384 keV
(b) The energies accepted within a window centered around a given energy are calculated as follows: energies within window = centerline energy +- (energy (keV) x % window as decimal) / 2 In this example: 364 keV +- 364 x 0.2 / 2 = 364 keV +- 36 364 keV +- 36 = 328 - 400 keV
100
A technologist changes the collimator on a gamma camera from a low-energy all-purpose collimator to a high-resolution collimator. If the same number of counts is acquired, how will the acquisition time change when the high-resolution collimator is used? (a)The acquisitions time will be the same with both collimators. (b) The acquisition time will increase. (c) the acquisition time will decrease. (d) The effect on acquisition time is unpredictable. (e) The effect on the acquisition time is determined by the sensitivity of the instrument.
(b) Because the holes are smaller and the septa are often longer in a high-resolution collimator, fewer photons pass through the channels and strike the crystal. This decreases sensitivity. Therefore, it would take more time to acquire the same number of counts using a high-resolution collimator.

ST Questions (8 decks)

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