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ST Questions > ST:3 > Flashcards

ST:3 Flashcards

1
Q

Static bone imaging is performed several hours after tracer administration to permit:
(a)maximum tracer uptake in the skeleton

(b) tracer clearance from normal bone tissue
(c) tracer clearance from sites of infiltration
(d) blood clearance of excess tracer
(e) tracer clearance from the kidneys

A

(d) Maximum skeletal uptake of [99mTc]medronate and [99mTc]oxidronate occurs within 45 min after tracer administration, and imaging is to allow the excess circulating tracer to be cleared from the blood by the kidneys. Such clearance is necessary to increase the target (bone) : non-target (soft tissue) ratio for an optimal image.

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2
Q

For which of the following clinical indications would limited bone imaging (“spot” views) be most appropriate?
(a)Rule out skeletal metastases.

(b) Evaluate Paget’s disease.
(c) Evaluate temporomandibular joint pain.
(d) With history of child abuse, rule out occult fractures.
(e) Rule out kidney stones.

A

(c) Paget’s disease, skeletal metastases, and occult fractures resulting from child abuse all have the potential to be widespread throughout the skeleton. For these conditions, because their extent is unknown before imaging, total-body bone imaging is indicated. Temporomandibular join (TMJ) pain is localized; therefore, “spot” view imaging of the skull, face (especially in the area of the TMJs), and cervical spine is indicated.

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3
Q

Three- or four-phase bone imaging is particularly useful when which of the following conditions is suspected?
(a)osteomyelitis

(b) osteoporosis
(c) skeletal metastases
(d) stress fracture
(e) compound fracture

A

(a) Early images are important in diagnosing inflammatory conditions such as osteomyelitis. The flow study, the first phase of a multiphase bone image, is important in demonstrating increased blood flow to the affected area. In osteomyelitis, tracer concentration remains increased throughout the other phases.

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4
Q

The standard views performed in a lung perfusion study are:
(a)anterior and posterior only

(b) posterior and obliques only
(c) anterior, posterior, and lateral of the affected lung
(d) laterals and obliques only
(e) anterior, posterior, laterals, and obliques

A

(e) At least six views should be performed in a lung perfusion study: anterior, posterior, right and left laterals, and right and left posterior obliques. Some authors recommend eight standard views; these plus right and left anterior obliques.

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5
Q

Upon completion of an imaging procedure, the patient sits up quickly and complains of dizziness and feeling faint. The most appropriate action for the technologist would be to:
(a)Have the patient stand and walk around the room.

(b) Check vital signs.
(c) Have the patient lie down again.
(d) talk with the patient and have the patient breathe slowly and deeply.
(e) Ask the patient if they have a family history of syncope.

A

(d) Initial feelings of dizziness and faintness when going from a recumbent to an upright position may be the result of a slight drop in blood pressure that occurs when the patient moves too quickly. To help minimize the severity of this orthostatic hypotension, the patient should be encouraged to talk and breathe slowly and deeply. Symptoms should subside within a few minutes. If they do not, the technologist should seek medical help for the patient.

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6
Q

All of the following statements about performing a lung ventilation study with [99mTc]pentetate aerosol are true, EXCEPT:
(a)Multiple projections may be obtained with one dose of tracer.

(b) The patient is disconnected from the nebulizer after inhalation of the aerosol.
(c) The patient is imaged while inhaling particles from the nebulizer.
(d) The face mask, tubing, and nebulizer must be disposed of as radioactive waste.
(e) Some residual tracer may be present in the esophagus.

A

(c) To perform a ventilation study with [99mTc]pentetate aerosol, the liquid tracer is placed into the nebulizer, where it is broken up into small airborne particles that are inhaled by the patient. The patient is connected to the nebulizer with tubing and a face mask or mouthpiece. After inhalation of the tracer, the patient is disconnected from the delivery apparatus. Then, the patient is imaged. Because the particles remain where they have been deposited for a period of time, the same views that are acquired for the perfusion images may be acquired for the ventilation images. The nebulizer, tubing, and face mask or mouthpiece all are contaminated with [99mTc]pentetate and must be handled as radioactive waste.

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7
Q

The purpose of wrapping the legs with elastic bandages before performing a radionuclide venogram with [99mTc]MAA is to:
(a)distend the veins in the feet

(b) prevent blood clots from traveling to the lung
(c) suppress superficial circulation
(d) trap the tracer in the lower extremities
(e) increase low blood pressure in the patient

A

(c) The purpose of radionuclide venography is to demonstrate the presence of thrombi in the deep veins of the legs and pelvis (internal iliacs). Therefore, elastic bandages are used to wrap the legs between the ankles and knees to divert blood flow from the superficial circulation to the deep venous system.

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8
Q

When the radiation level coming from a radioiodine therapy patient in isolation is measured, it should be measured:
(a)every day

(b) every day at the same time
(c) at the same distance from the patient each time
(d) every day and at the same distance from the patient each time
(e) at different distances from the patient each time

A

(d) It is important to monitor a radioiodine therapy patient daily to determine the earliest possible release from isolation. The measurement should be performed using the same instrument and counting geometry each time the radiation level is monitored to permit comparison of measurements.

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9
Q

The function of a draw sheet is to provide:
(a)support for the patient during a stretcher to bed transfer

(b) warmth to the patient during the procedure
(c) protection from infectious disease
(d) patient privacy during an imaging procedure
(e) an activity for the patient during transfer

A

(a) The draw sheet is the one on which the patient is lying and is used for transferring the patient from stretcher to imaging table.

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10
Q

A gated equilibrium ventricular function study can be performed with which of the following 99mTc-labeled tracers?
(a)pentetate

(b) medronate
(c) human serum albumin
(d) pyrophosphate
(e) macro aggregated albumin

A

(c) An equilibrium ventricular function study requires a radiopharmaceutical that remains in the blood pool. Many departments label the patient’s red blood cells with [99mTc]pertechnetate, but other facilities prefer the immediate availability of [99mTc]albumin. Currently, [99mTc]albumin is available only outside the United States.

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11
Q

Which of the following diagrams is a correctly labeled representative slice of the horizontal long axis of the left ventricular myocardium?
(a) _\

(b) O
(c) ^
(d) >

A

(c) All of the diagrams are correctly labeled cross-sectional slices of the heart: (1) transaxial, (b) short axis, (c) horizontal long axis, and (d) vertical long axis.

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12
Q

Stress-rest myocardial imaging performed with [99mTc]sestamibi requires two administrations of tracer, because the tracer:
(a)does not redistribute once it has been taken up by the myocardium

(b) rapidly washes out of the myocardium after administration
(c) has too short a half-life to permit delayed imaging
(d) must be administered immediately after its preparation
(e) has a fast biological half-life

A

(a) [99mTc]sestamibi is taken up into the myocardium in proportion to blood flow. It is taken into the myocardial cells, bound, and retained in the myocardium. Therefore, it does not redistribute the way [201Tl]thallous chloride does, making it necessary to administer tracer for both the stress and rest portions of the examination.

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13
Q

In a normal hepatobiliary study, which of the following structures will NOT be visualized?
(a)liver

(b) common bile duct
(c) spleen
(d) gallbladder
(e) intestines

A

(c) Hepatobiliary agents are cleared from the blood by the hepatocytes in the liver. The tracer is cleared from the hepatocytes into the common bile duct and gallbladder, and from there into the small intestine.

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14
Q

In preparation for hepatobiliary imaging, patients are required to fast to:
(a)prevent renal uptake of the tracer

(b) enhance liver uptake of the tracer
(c) minimize the risk of radioactive emesis
(d) avoid stimulating the gallbladder
(e) avoid gastric interference

A

(d) Ingestion of food may cause the gallbladder to contract, potentially causing a false-positive result; that is, the gallbladder is not visualized. While the gallbladder is contracting, tracer will not be able to flow into it.

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15
Q

To determine the patency of a LeVeen shunt, the radiopharmaceutical is administered into:
(a)a vein

(b) the circle of Willis
(c) the intrathecal space
(d) the shunt tubing
(e) the peritoneal cavity

A

(e) The physician performs an intraperitoneal injection of the tracer.

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16
Q

Which of the following is the correct patient/camera positioning for imaging a transplanted kidney?
Patient position - Camera placement
(a)Supine - Anterior

(b) Upright - Posterior
(c) Upright - Anterior
(d) Supine - Posterior
(e) Supine - Oblique

A

(a) A transplanted kidney is placed in the iliac fossa. Therefore, a transplanted kidney should be imaged with the patient supine and the camera placed anteriorly over the pelvis.

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17
Q

In performing an effective renal plasma flow determination, the injection site should be imaged to:
(a)quantitate the amount of tracer deposited at the injection site

(b) calculate the amount of injected activity
(c) rule out tracer infiltration
(d) correct the kidney transit time of the tracer
(e) correct the urinary output graph

A

(c) Because an ERPF is a quantitative study, any tracer infiltration will invalidate the calculated ERPF values. Therefore, it is essential to confirm that the entire amount of activity was injected into the circulatory system.

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18
Q

Radionuclide cystography performed by the direct method requires which of the following?
(a)intravenous injection of the tracer

(b) use of a renal agent
(c) administration of furosemide
(d) catheterization of the patient
(e) calculation of the ERPF

A

(d) Direct radionuclide cystography requires that the patient be catheterized and the bladder drained. The tracer is then instilled into the bladder with saline. Although [99mTc]pentetate, a renal agent, may be used, it is not required. [99mTc]sulfur colloid or [99mTc]pertechnetate may be used.

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19
Q

All of the following conditions may demonstrate uptake of 111In-labeled leukocytes EXCEPT:
(a)osteomyelitis

(b) pulmonary embolism
(c) dental abscess
(d) ostomy site
(e) fever of unknown origin

A

(b) Leukocytes accumulate in areas of infection or inflammation. Thus, they would accumulate at ostomy sites, in osteomyelitis, and in dental abscesses.

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20
Q

Signs/symptoms that a patient is going into anaphylactic shock include all of the following EXCEPT:
(a)skin splotches

(b) pallor
(c) restlessness
(d) tachycardia
(e) hot, dry skin

A

(e) Pale, cold, clammy skin is characteristic of shock. The patient may also exhibit restlessness and tachycardia.

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21
Q

Which of the following radiopharmaceuticals crosses the intact blood-brain barrier?
(a)[99mTc]pertechnetate

(b) [99mTc]gluceptate
(c) [99mTc]pentetate
(d) [99mTc]bicisate
(e) [99mTc]sulfur colloid

A

(d) [99mTc]gluceptate, [99mTc]pentetate, and [99mTc]pertechnetate cross the blood-brain barrier only if disease has caused a disruption in the barrier. Therefore, these agents remain in the blood pool unless there is a disruption in the blood-brain barrier. [99mTc]bicisate and [99mTc]exametazime normally cross the blood-brain barrier and are taken up in brain tissue in proportion to blood flow.

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22
Q

The patency of ventriculoperitoneal shunts may be assessed with which of the following tracers?
(a)[111In]chloride

(b) [99mTc]MAA
(c) [99mTc]bicisate
(d) [99mTc]pertechnetate
(e) [99mTc]pentetate

A

(d) A ventriculoperitoneal shunt is designed to treat hydrocephalus by directing excess cerebral spinal fluid into the peritoneal cavity, where it is absorbed into the circulation. The patency of the shunt can be ascertained by injecting a tracer, typically [99mTc]pertechnetate, into the shunt tubing and imaging the movement of the tracer down the tube into the peritoneum. Because of the short duration of this examination, 99mTc may be used.

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23
Q

According to the FDA, written informed consent must be obtained to administer which of the following radiopharmaceuticals?
(a)[123I]sodium iodide

(b) [99mTc]sestamibi
(c) [131I]sodium iodide
(d) [99mTc]bicisate
(e) [125I]sodium iodide

A

(c) Written consent must be obtained for any radiopharmaceutical that is investigational. These drugs are referred to as investigational new drugs (INDs). All of the radiopharmaceuticals cited in this publication have been approved by the FDA for clinical use. That is, their new drug authorization (NDA) has been approved, and they are referred to as NDA drugs.

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24
Q

Patient preparation for [89Sr]chloride therapy includes all of the following EXCEPT:
(a)nuclear medicine bone imaging

(b) complete blood count
(c) discontinuation of pain medication
(d) renal function studies
(e) correlated physical exam

A

(c) Patient preparation for [89Sr]chloride therapy includes total-body bone imaging to demonstrate increased tracer uptake in painful metastatic sites, a complete blood count to confirm adequate platelet and white blood cell counts, and renal function studies because the major route of tracer excretion is through the kidneys.

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25
Patient preparation for 131I therapy for thyroid cancer includes all of the following EXCEPT: (a)ruling out pregnancy (b) diet restrictions (c) reviewing isolation requirements (d) discontinuing breast-feeding (e) administering oral potassium iodide
(e) In preparation for 131I therapy for thyroid cancer, the patient will have to be instructed about the requirements and limitations associated with being in isolation. If the patient is female, a pregnancy test MUST BE PERFORMED IMMEDIATELY BEFORE THE RADIOIODINE IS ADMINISTERED. PREGNANCY IS AN ABSOLUTE CONTRAINDICATION to 131I therapy. If the woman is breast-feeding, she must discontinue this activity. Oral potassium iodide may be administered to personnel who are exposed to airborne radioiodine as a means of preventing tracer uptake in the thyroid gland.
26
One verification method used to ensure that the correct radiopharmaceutical is being administered is to check the label found on the vial. The best times to check this label would include all of the following EXCEPT: (a)before the vial is removed from the shelf (b) before the radiopharmaceuticals is dispensed (c) after the vial is placed back on the shelf (d) after the radiopharmaceutical is administered to the patient (e) after the syringe shield is added
(d) Verification should be done before injection, and the label should be checked when the radiopharmaceutical is removed from the shelf, when it is dispensed, and when it is returned to the shelf.
27
When dual-radionuclide myocardial perfusion imaging is performed, which of the following tracers are used for stress and which for rest? Stress - Rest (a)[99mTc]Sestamibi - [99mTc]Teboroxime (b) [201Tl]Thallous chloride - [99mTc]Sestamibi (c) [99mTc]Sestamibi - [201Tl]Thallous chloride (d) [99mTc]Sestamibi - [99mTc]labeled red blood cells (e) [99mTc]Sestamibi - [99mTc]sulfur colloid
(c) The dual-radionuclide myocardial perfusion imaging protocol used [99mTc]sestamibi for stress imaging and [201Tl]thallous chloride for rest imaging. [99mTc]tetrofosmin may be used in place of [99mTc]sestamibi. The dual-radionuclide protocol shortens the time that patients spend in the imaging department and is useful for evaluating myocardial ischemia and viability.
28
If [99mTc]sulfur colloid is administered to demonstrate gastrointestinal bleeding, the bleeding can be best visualized how long after the radiopharmaceutical is administered? (a)20-30 min (b) 10-15 min (c) 45 min - 1 hr (d) Anytime up to 24 hr (e) Anytime up to 48 hr
(b) [99mTc]sulfur colloid is cleared from the blood and localized in the liver and spleen within 15 min of administration. Therefore, to demonstrate gastrointestinal bleeding with this tracer, it will have to occur while the tracer is still circulating.
29
Which of the following areas is the recommended injection site for a cardiac first-pass study? (a)axillary vein (b) cephalic vein (c) median basilica vein (d) dorsal vein (e) carotid vein
(c) A cardiac first-pass study requires a bolus injection technique to demonstrate each of the cardiac chambers separately. Therefore, a large peripheral vein, such as the median antecubital or external jugular, is needed.
30
Patient preparation for a 131I therapy includes: (a)a low-iodine diet for 1 week before the therapy (b) a high-iodine diet for 1 week before the therapy (c) a low-carbohydrate diet fro 3 days before the therapy (d) not consuming any salt for 1 week before the therapy (e) not consuming potassium for 1 week before the therapy
(a) Patient preparation for 131I therapy includes a low iodine diet for 1 week prior to therapy to help increase the ability of the thyroid gland or metastatic cancer as a whole to uptake the radioactive 131I versus stable iodine. This will allow for a better uptake of the 131I.
31
For a 67Ga infection imaging, the proper route of administration of the radiopharmaceutical is what? (a)by inhalation (b) intramuscularly (c) orally (d) intravenously (e) intrathecal
(d) The proper route of administration for 67Ga infection imaging is intravenously.
32
Which of the following statements best describes the preferred injection and blood sampling site(s) when performing a plasma volume? (a)Place a butterfly needle in an antecubital vein for injection of the radiopharmaceutical and subsequent blood sampling. (b) Intravenous injection should be performed in an antecubital vein, and subsequent blood samples should be obtained from the same vein. (c) Intravenous injection should be performed in an antecubital vein in one arm, and subsequent blood samples should be obtained from an antecubital vein in the opposite arm. (d) Intravenous injection should be performed in an antecubital vein, and subsequent blood samples should be obtained from a different antecubital vein in the same arm. (e) An angiocath should be placed in an antecubital vein for injection of the radiopharmaceutical and subsequent blood sampling.
(c) Because radioiodinated serum albumin is "sticky," it has a tendency to adhere to substances, including tissue. Tracer administration and blood sampling should be performed, if possible, in contralateral arms.
33
When administering an intravenous injection, the needle should be inserted into the view at an angle of: (a)90 (b) 45 (c) 5 (d) 15 (e) 1
(d) An intravenous injection should be done with the needle at about a 15-degree angle to the vein it is being inserted into.
34
When counting 51Cr red blood cell samples in scintillation well counter, the window should be set around the photopeak at: (a)320 keV (b) 159 keV (c) 81 keV (d) 511 keV (e) 664 keV
(a) The gamma energy of 51Cr is 320 keV. Therefore, the scintillation detector should be set to accommodate this photopeak.
35
Which tomographic plane of the heart displays all walls of the left ventricle? (a)horizontal long axis (b) short axis (c) transaxial (d) vertical long axis (e) sagittal
(b) The short-axis slice displays all walls of the left ventricle.
36
When performing a radioiodine thyroid uptake with an uptake probe, the most appropriate collimator to use is a: (a)low-energy, high-sensitivity parallel-hole collimator (b) converging collimator (c) flat-field collimator (d) straight-bore collimator (e) diverging collimator
(c) A scintillation probe with a flat-field-of-view collimator is used for a radioiodine uptake test. The flat-field collimator allows for small variations in organ depth without affecting statistical accuracy.
37
Which of the following would NOT be in accordance with electrical safety guidelines? (a)use of three-pronged plugs and outlets (b) keeping walk areas free from electrical cords (c) disconnecting an electrical plug from the wall by pulling on the cord (d) not using frayed or kinked cords (e) using a 25 amp appliance in a 30 amp outlet
(c) Cords should be disconnected from the wall by grasping and pulling on the plug, NOT on the cord.
38
Which of the following statements about the image of a left ventricle slice shown here is correct? _____apex septum ^ lateral wall _____base (a)It is an incorrectly labeled image of a vertical long axis slice. (b) It is an incorrectly labeled image of a horizontal long axis slice. (c) It is a correctly labeled image of a vertical long axis slice. (d) It is a correctly labeled image of a horizontal long axis slice. (e) It is a correctly labeled image of a short axis slice.
(d) It is a correctly labeled image of a horizontal long-axis slice of the left ventricle.
39
When using [18F]FDG for PET imaging, which of the following should be considered as a contraindication for performing the study? (a)low-carb diet (b) blood glucose level of 120 mg/dL (c) high-iodine diet within past week (d) low-iodine diet within past week (e) blood glucose level of 200 mg/dL
(e) Ideally, the blood glucose should be less than 120 mg/dL when imaging with [18F]FDG. The [18F]FDG competes for glucose receptors, and a high blood glucose level reduced potential uptake of the [18F]FDG.
40
A 1:25 dilution of a solution with a concentration of 10 uCi/mL is prepared. What is the tracer concentration in the dilution? (a)0.04 uCi/mL (b) 0.25 uCi/mL (c) 2.5 uCi/mL (d) 0.4 uCi/mL (e) 4.5 uCi/mL
(d) A 1:25 dilution means that the concentration in the diluted solution is 1/25 of the original concentration. Thus: 1/25 x 10 uCi/mL = 0.4 uCi/mL
41
In preparation for [18F]fluorodeoxyglucose (FDG) imaging, patients are required to fast to: (a)prevent hypoglycemic episodes (b) enhance cardiac uptake (c) eliminate the need for laxatives (d) maximize tumor uptake (e) prevent brown fat disposition
(d) In preparation for [18F]fluorodeoxyglucose (FDG) imaging, patients are required to fast to maximize tumor uptake. More [18F]FDG is taken up by cancer cells when the extracellular concentration of glucose is low, which enhances the detection of tumors.
42
Which of the following steps is performed before the administration of [90Y]ibritumomab tiuxetan therapy? (a)determining PSA level (b) fasting for 8 hr (c) NPO from midnight before the study (d) intravenous hydration for 4 hr (e) whole-body imaging with [111In]ibritumomab tiuxetan
(e) Before administration of [90Y]ibritumomab tiuxetan therapy, a whole-body image is performed with [111In]ibritumomab tiuxetan to assess the biodistribution of the antibody and to identify areas of normal tissue that may be at risk of exposure to a high radiation dose because of proximity to the tumor.
43
The size of a 99Mo/99mTc generator is expressed as the total activity of: (a)99mTc on the column (b) 99Mo on the column (c) 99mTc eluted from the column (d) decay-corrected 99mTc available at time of elution (e) decay-corrected 99Mo available at time of elution
(b) The size of a 99Mo/99mTc generator is expressed as the total 99Mo activity on the column at the time of initial assay (calibration).
44
If 1.2 Ci of 99mTc are eluted from a generator in a 5.7 mL volume, what is the concentration of the eluate? (a)210 mCi/mL (b) 475 mCi/mL (c) 32.4 mCi/mL (d) 5.7 mCi/mL (e) 7.5 mCi/mL
(a) Concentration is expressed as activity per unit volume. It is obtained by dividing the total volume into the total activity. In this case: 1. 2 Ci / 5.7 mL = 0.210 Ci/mL 0. 210 Ci x 1000 mCi / 1 Ci = 210 mCi
45
If 633 mCi are expected to be eluted from a wet column generator, what volume evacuated vial should be use to obtain an eluate concentration of approximately 30 mCi/mL? (a)20 mL (b) 10 mL (c) 15 mL (d) 5 mL (e) 25 mL
(a) The amount of 99mTc activity eluted from the column will be the same whether 5 or 20 mL of saline are used for elution. For a wet-column generator, however, the eluate concentration is determined by the volume of saline drawn from the supply contained within the generator. The volume of saline is controlled by the volume of the evacuated vial used to remove the eluate. Lower-volume evacuated vials provide eluate with greater concentration, and higher-volume vial produce eluate with lower concentration. In this example, the eluate volume is unknown. Thus: concentration = total activity / eluate volume eluate volume = total activity / desired concentration = 632 mCi/mL / 30 mCi/mL = 21 mL A 21 mL evacuated vial is not available, but the 20 mL vial will produce an eluate with a concentration of 31.6 mCi/mL (approximately 30 mCi/mL): concentration = 632 mCi/ mL / 20 mCi/mL = 31.6 mCi/mL
46
The maximum allowable limit of Al3+ in 99mTc eluate is set by the: (a)Nuclear Regulatory Commission (b) Environmental Protection Agency (c) U.S. Pharmacopeia (d) U.S. Department of Transportation (e) U.S. Department of Energy
(c) Aluminum is a nonradioactive, chemical impurity. The allowable limit is set by the U.S. Pharmacopeia.
47
If the following measurements were obtained form an assay of 99mTc eluate: 99Mo, 8 uCi 99mTc, 652 mCi then the 99Mo concentration in 1 mCi of 99mTc is: (a)81.5 uCi/mCi (b) 8.0 uCi/mCi (c) 0.000012 uCi/mCi (d) 0.012 uCi/mCi (e) 0.0012 uCi/mCi
(d) 99Mo concentration is expressed as a ratio of the number of microcuries of 99Mo to the number of millicuries of 99mTc. Thus, 99Mo concentration is equal to: 8 uCi / 652 mCi = 0.012 uCi 99Mo/mCi 99mTc
48
Increased levels of Al3+ in 99mTc eluate used to prepare [99mTc]sulfur colloid may cause the tracer to concentrate in the: (a)liver (b) lungs (c) red blood cells (d) thyroid (e) brain
(b) High levels of aluminum of aluminum ions in 99mTc eluate cause the colloidal particles in [99mTc]sulfur colloid to clump together, forming particles large enough to be trapped in the blood vessls of the lung. Many sulfur colloid kits contain EDTA, an agent that binds the Al+3 ions and prevents the aggregation of the colloidal particles into larger ones.
49
Which of the following radiopharmaceuticals may be ordered to treat bone pain caused by bony metastases? (a)[131I]sodium iodide (b) [111In]oxine (c) [32P]chromic phosphate (d) [153Sm]lexidronam (e) [123I]sodium iodide
(d) Of the radiopharmaceuticals listed, [153Sm]lexidronam is the agent used for treating bone pain. [131I]sodium iodide is used to treat hyperthyroidism or metastatic thyroid carcinoma. [111In]oxine is used to label white blood cells for infection imaging. [32P]chromic phosphate is used to treat pleural or peritoneal effusions.
50
According to NRC regulations, reports of medical events sent to the NRC must include all of the following information EXCEPT: (a)whether the patient or a relative was notified (b) a description of the incident (c) the patient's name (d) the referring physician's name (e) why the event occurred
(c) According to the NRC, reports of medical events made to the NRC should contain the following information: names of all individuals involved in the event except the patient, whether the patient or a relative was notified, a description of the incident and why it occurred, the effect on the patient, and remedial actions to prevent recurrence. The patient must NOT be identified to the NRC.
51
All of the following radiopharmaceuticals are prepared with reduced [99mTc]pertechnetate EXCEPT: (a)[99mTc]medronate (b) [99mTc]oxidronate (c) [99mTc]macroaggregated albumin (d) [99mTc]lidofenin (e) [99mTc]sulfur colloid
(e) Most 99mTc compounds are prepared with chemically reduced 99mTc, a more-chemically active form of technetium. 99mTc labeling is accomplished in the presence of a stannous compound that acts as a reducing agent. The stannous ion (Sn+2) reduces the valence state of the technetium in the pertechnetate ion from +7 to +4 or to another reduced valence state. The reduced 99mTc is a more reactive species, capable of combining with a variety of compounds, such as oxidronate, macro-aggregated albumin, and lidofenin. [99mTc]sulfur colloid incorporates 99mTc in the unreduced, +7 valence state. Therefore, a reducing agent is not required. The first step in the preparation of [99mTc]sulfur colloid involves heating together [99mTc]pertechnetate, an acid, and sodium thiosulfate. During the heating, the elemental sulfur precipitates out of the solution and condenses to form colloidal-sized particles. The 99mTc is trapped and contained within the particles as they form.
52
``` What is the approximate final concentration of the [99mTc]sulfur colloid if 125 mCi are prepared using the following reagents? Sulfur colloid kit Reaction vial: 0.5 mL acid Syringe A: 1.1 mL thiosulfate mixture Syringe B: 2.1 mL buffer Maximum activity to be added: 400 mCi 99mTc volume to be added: 0.5-5.0 mL [99mTc]pertechnetate Concentration: 26.7 mCi/mL Total volume: 8.0 mL (a)33.8 mCi/mL ``` (b) 15.8 mCi/mL (c) 21.3 mCi/mL (d) 14.9 mCi/mL (e) 38.3 mCi/mL
(d) The concentration of the [99mTc]sulfur colloid is equal to the amount of radioactivity added to the kit divided by the volume of all the liquid reagents. The volume of 99mTc required is: volume = 99mTc activity required / [99mTc]pertechnetate concentration = 125 mCi / 26.7 mCi/mL = 4.7 mL of 99mTc The total kit volume is equal to: 99mTc volume + acid volume + syringe A volume = 4.7 mL +0.5 mL +1.1 mL +2.1 mL = 8.4 mL The final kit concentration is equal to: 99mTc activity / total volume = 125 mCi / 8.4 mL = 14.9 mCi/mL
53
On the basis of the USP criteria, which of the following statements about the particle size of MAA preparation is true? (a)No particles should exceed 90 um in diameter. (b) All particles have the same diameter. (c) Some particles may be smaller than 10 um. (d) Up to 10% of the particles may exceed 150 um in diameter. (e) Up to 25% of the particles may exceed 150 um in diameter.
(c) According to the USP, 90% of the particles in an MAA preparation should be 10-90 microns in size. no particles should be larger than 150 microns.
54
An eluate of [99mTc]pertechnetate is assayed for 99Mo contamination immediately after elution. If the 99Mo breakthrough is determined to be 0.035 uCi 99Mo/mCi 99mTc and the shelf-life of the eluate is 12 hr, for how many hours after elution can the [99mTc]pertechnetate be administered to patients? (a)6 hr (b) 8 hr (c) 18 hr (d) 12 hr (e) 24 hr
(d) The user must ascertain that 99Mo contamination does not exceed the maximum acceptable limits within the 12-hr period that the eluate may be used. Therefore, decay correct the initial 99Mo concentration for 12 hr to determine its concentration at the end of the time the eluate may be used: 99Mo: 0.035 uCi x 0.881 = 0.031 99mTc: 1 mCi x 0.251 = 0.251 mCi The 99Mo concentration 12 hr after elution is: 0.035 uCi 99Mo / 0.251 mCi 99mTc = 0.139 uCi 99Mo/mCi 99mTc This level is below the maximum allowable limit of 0.15 uCi 99Mo/mCi 99mTc set by the NRC. Therefore, this eluate may be used for 12 hr after elution.
55
The radiochemical purity of a radiopharmaceutical is determined using a solvent/support media combination with these Rf values: Radiopharmaceutical: 0 Radiochemical impurity: 1.0 After the radiochromatography strip is developed and cut in half, the solvent fron half of the strip counted 15,345 cpm and the orgin half of the strip counted 55,632 cpm. What is the radiochemical purity of the sample? (a)78.4% (b) 27.6% (c) 72.4% (d) 21.6% (e) 89.9%
(a) Based on the Rf values, the radiopharmaceutical is present on the origin half of the strip, and the radiochemical impurity is present on the solvent front half of the strip. The radiochemical purity is: counts on origin half of strip x 100/total counts (counts on both strips)
56
On the basis of the radiopharmaceutical vial label information shown here, which of the preparations should the technologist administer on Jul 9 at 0800 to perform three-phase bone imaging? Vial - Radiopharmaceutical - Assay time/date - Expiration time/date (a)A - [99mTc]bicisate - 0700/July 9 - 1900/July 9 (b) B - [99mTc]medronate - 0600/July 8 - 1400/July 8 (c) C - [99mTc]pertechnetate - 0600/July 9 - 1800/July 9 (d) D - [99mTc]oxidronate - 0600/July 9 - 1400/July 9 (e) E - [99mTc]sulfur colloid - 0600/July 9 - 1400/July 9
(d) Three-phase bone imaging is performed with a bone-seeking agent. According to the label on vial D, the vial contains a bone-imaging agent that has not expired. Vial B contains the previous day's bone agent that has expired. Vials C and E contain radiopharmaceuticals that are not appropriate for performing three-phase bone imaging.
57
The standard adult dosage of [I123]sodium iodide is 400 uCi +-10%. On the basis of the vial label information shown here: Total activity: 1 mCi Number of capsules: 10 Activity/capsule: 100 uCi/capsule Calibration: 1200, October 5 how many [123I]sodium iodide capsules should be administered to the patient at 0800 on October 5? (a)four (b) The capsules may not be administered until 1200. (c) two (d) three (e) five
(d) the elapsed time between calibration and capsule administration is 4 hr. In this example, the radiopharmaceutical is being used before calibration time. Therefore, the activity in a capsule at 0800 is unknown, and the known activity (calibration activity) is divided by the decay factor: A(0) x 0.810 = 100 uCi/capsule A(0) = 100 uCi/capsule /0.810 = 123 uCi/capsule at 0800 Because the prescribed dose is 400 uCi +- 10% (or 360 - 440 uCi), the total activity in the number of capsules the patient receives must be within this range. Four capsules contain 492 uCi) 4 capsules x 123 uCi/capsule), an activity that exceeds the prescribed dose. Three capsules contain 369 uCi, an amount within the prescribed 360-440 uCi. Two capsules contain 246 uCi, an amount below what is prescribed.
58
A technologist needs 185 MBq [131I]sodium iodide solution on November 3. The label on the radiopharmaceutical vial contains the following information: Total activity: 740 MBq Total volume: 10 mL Assay: 1200, October 28 What volume is required to obtain the necessary activity on November 3? (a)0.42 mL (b) 4.2 mL (c) 1.5 mL (d) 4.6 mL (e) 5.2 mL
(b) The elapsed time between calibration and dose calculation is 6 days (October 28-November 3; remember that October has 31 days). The concentration on October 28 is 74 MBq/mL (740 MBq/10 mL). Decay correct the initial concentration for 6 days using the appropriate decay factor for 131I: 74 MBq/mL x 0.597 = 44.2 MBq/mL Then, determine the required volume: volume=activity required/C(t) = 185 MBq / 44.2 MBq/mL = 4.2 mL
59
In labeling red blood cells with [51Cr]sodium chromate, which of the following reagents is used to prevent the blood sample from coagulating? (a)heparin (b) EDTA (c) ACD solution (d) sodium fluoride (e) sodium chloride
(c) ACD solution, EDTA, heparin, and sodium fluoride all may be used as anticoagulants. However, for labeling red blood cells with 51Cr, ACD (acid citrate dextrose) solution is the anticoagulant of choice.
60
Which of the following medications has been shown to interfere with in vivo 99mTc labeling of red blood cells? (a)doxorubicin (b) heparin (c) penicillin (d) adenosine (e) dobutamine
(b) Certain drugs interfere with 99mTc red blood cell labeling because they inhibit the transport of the stannous ion through the red cell membrane and, hence, entry of [99mTc]pertechnetate into the red cell.
61
[99mTc]pentetate was prepared using the following reagents: Pentetate kit Reconstituting volume: 1-8 mL [99mTc]pertechnetate Activity range: 3-160 mCi [99mTc]pertechnetate Concentration: 25.0 mCi/mL Total volume: 5.0 mL Which of the following dose calibrator readings would verify that the maximum activity of [99mTc]pentetate was prepared from the reagents available? (a)100 mCi (b) 160 mCi (c) 125 mCi (d) 200 mCi (e) 300 mCi
(c) The maximum activity that can be made from one pentetate kit is 160 mCi. However, based on the amount of [99mTc]pertechnetate available, only 125 mCi (25.0 mCi/mL x 5.0 mL) can be prepared; 5.0 mL is also within the reconstituting volume limits (1-8 mL) of the kit.
62
In the radiopharmacy laboratory, good radiation protection technique includes which of the following practices? (a)wearing disposable gloves when withdrawing unit doses (b) manipulating needles, syringes, and vials containing radioactivity at arm's length (c) using syringe shields when preparing unit doses (d) wearing disposable gloves when giving injections (e) using a butterfly setup when giving injections
(c) Disposable gloves serve as a barrier against skin contamination when handling radioactive materials. Syringe shields absorb photon emissions that can dramatically increase radiation exposure to hands and fingers. Keeping radioactive materials at arm's length increases distance between the source and the eyes and torso, thereby decreasing radiation exposure to these areas.
63
If [99mTc]exametazime is prepared at 0900 to label white blood cells, it should be used no later than what time? (a)1300 (b) 1100 (c) 0900 (d) 1500 (e) 1700
(c) When [99mTc]exametazime is used to label white blood cells, methylene blue stabilizer is omitted from its preparation. For this reason, the preparation should be used within 30 min.
64
Upon visual inspection, a vial of [99mTc]medronate appears to be white and slightly turbid. Which of the following actions should the technologist perform next? (a)Prepare unit doses from the vial. (b) Adjust the pH of the preparation. (c) Add a diluent to the vial (d) Filter the preparation with a membrane filter (e) Prepare another vial of [99mTc]medronate.
(e) [99mTc]medronate, a bone agent, should be a clear, colorless solution. Therefore, the technologist should not use the original vail because of its abnormal appearance.
65
On the basis of the chromatography results shown here: what is the percentage radiochemical impurity of the [99mTc]pentetate preparation? Origin - Solvent front System 1 - 3 uCi HR-Tc - 177uCi [99mTc]pentetate + [99mTc]pertechnetate System 2 - 275 uCi [99mTc]pentetate + HR-Tc - 15 uCi [99mTc]pertechnetate What is the percentage radiochemical impurity of the [99mTc]pentetate preparation? (a)74.6% (b) 93.1% (c) 94.8% (d) 98.3% (e) 6.9%
(e) The hydrolyzed-reduced 99mTc impurity is separated using system #1, and the free pertechnetate impurity is separated using system #2. Therefore, the percentage of each impurity in the preparation can be determined directly: % HR-99mTc = 3 uCi x100 / (3 uCi+177 uCi) =1.7% % free pertechnetate = 15 uCi x100 / (15 uCi +275 uCi) = 5.2% The radiochemical impurity of the sample is: %HR-99mTc + % free pertechnetate = 1.7% + 5.2% = 6.9%
66
Which of the following is considered a Quality Control daily test for a CT scanner? (a)linearity of CT numbers (b) low- and high-contrast resolution (c) image slice thickness (d) CT number accuracy (e) spatial resolution
(d) Daily QC tests include warm-up of the x-ray tube, verification of tube output and detector response at various kVp and mA settings, and evaluation of tomographic uniformity, CT number accuracy, and image noise at clinical scanning parameters.
67
Of the following needles, which size is the most likely to cause coring of the rubber closure of a medication vial? Gauge - Length (a)16 - 1.5 in (b) 25 - 3/4 in (c) 22 - 1 in (d) 27 - 3/8 in (e) 10 - 1.0 in
(e) Larger-gauge needles are more likely to damage the rubber closure, especially after multiple withdrawals, causing pieces to fall into the solution in the vial. This is referred to as "coring." Needle gauges of 20-27 are less likely to cause coring with repeated withdrawals.
68
According to NRC regulations, which of the following signs should be posted on the door of a radiopharmacy laboratory in which radiation levels have been measured to be 7.5 mR/hr? (a)"Caution: Radiation Area" (b) "Caution: Radiation Materials" (c) No posting is required. (d) "Caution: High Radiation Area" (e) "Caution: Very High Radiation Area"
(a) The NRC requires that restricted areas, such as a radiopharmacy lab, be posted with specifically worded signs depending on the radiation level present. A "Caution: Radiation Area" sign should be posted when an individual could receive more than 5 mRem in an hour.
69
To determine the transportation index for a package containing radioactive material, the package must be monitored at: (a)the surface of the package (b) 6 in from the surface (c) 1 m from the surface (d) 2 m from the surface (e) 3 m from the surface
(c) The U.S. Department of Transportation defines the transportation index of a package containing radioactive materials to be the dose rate measured at 1 meter from the surface of the package.
70
To comply with NRC regulations, personnel radiation exposure records must be maintained: (a)for 3 years (b) indefinitely (c) for 5 years (d) for 5 years (e) for 7 years
(b) According to the NRC, personnel radiation exposure records must be retained indefinitely.
71
If a point source produces an exposure rate of 50 mR/hr at a distance of 1 foot, at what distance from the source wil the exposure rate be reduced to 2 mR/hr? (a)5.5 ft (b) 5 ft (c) 10 ft (d) 25 ft (e) 50 ft
``` (b) Use the inverse square law: (I1)(D1)^2 = (I2)(D2)^2 where I is the intensity at original distance (D1) and I2 is the intensity at new distance (D2). In this example: (50 mR/hr)(1ft)^2 = (2 mR/hr)(D2)^2 Isolate the unknown and solve: (D2)^2 = ((50 mR/hr)(1ft)^2)/ 2mR/hr (D2)^2 = 25 ft^2 Take the square root of each side: D2 = 5 ft ```
72
An occupationally exposed worker who is required to wear a personal radiation monitor must wear it at work EXCEPT when: (a)leaving the nuclear medicine department (b) radiation exposure results from patients who had radioactive materials administered at another facility (c) badge readings are likely to exceed allowable limits (d) personally undergoing a radiographic or nuclear medicine procedure (e) calibrating equipment
(d) An occupationally exposed worker should not wear a personal monitor when undergoing medical procedures that involve radiation. The monitor reading must reflect only the occupational exposure. The monitor should be worn anywhere in the workplace where the technologist may be exposed to radiation, whether within the nuclear medicine department or in other departments or patient rooms. Since monitors are worn to determine whether the worker is being exposed to acceptable levels, removal of the monitor to prevent excessive readings is self-defeating.
73
According to the NRC, a written directive for the administration of 15 mCi of [131I]sodium iodide must include the following information: (a)patient's thyroid uptake value (b) dosage (c) patient's birth date (d) lot number of the radiopharmaceutical (e) patient's name
(b) A written directive for administration of [131I]sodium iodide in dosages greater than 30 mCi (1.11 MBq) must include the patient's name 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 annual radiation exposure to members of the general public must be limited to no more than: (a)500 mRem (b) 2 mRem (c) 50 mRem (d) 100 mRem (e) 1 mRem
(d) According to NRC regulations, the annual radiation exposure to members of the general public is limited to 100 mRem.
75
Which of the following materials is the best choice for shielding 32P? (a)lead (b) aluminum (c) plastic (d) No shielding is required for 32P (e) tungsten
(c) 32P is a pure beta-emitting radionuclide. When it is placed in shielding material of a higher atomic number (Z), such as lead or aluminum, bremsstrahlung radiation is produced. this type of x-radiation results from the deceleration of beta particles as they approach the positively charged nuclei of the shielding material. As the beta particles slow down, they lose energy that is emitted as an x-ray. Shielding materials of lower atomic number, such as plastic, minimize the production of bremsstrahlung radiation.
76
A technologist is measuring room background with an end-window G-M survey meter. The meter shows the following reading: (needle at 0.1 and knob at x100) What should the technologist do next? (a)Adjust the scale of the meter. (b) Record the meter reading as the room background. (c) Choose another area of the room to measure background. (d) Recalibrate the survey meter. (e) Check the probe for contamination.
(a) Before any measurements are taken with a survey meter, the meter should be set on the lowest scale. If the needle of the meter reaches the endpoint at the higher end of the scale, the scale should be adjusted upward until the needle registers a value between zero and the high endpoint of the scale.
77
During a routine room survey for radioactive contamination, a technologist identifies an area on the floor that exceeds the trigger level. Which of the following should the technologist do next? (a)Determine the identity of the radionuclide present in the contaminated area. (b) Ascertain the source of the contamination. (c) Perform a dose calibrator background determination. (d) Cover the area until it has decayed to background level. (e) Perform a wipe test to determine if the contamination is removable.
(e) The trigger level is the exposure rate at which decontamination is performed. this level is set by each licensee with the assistance of the radiation safety officer. A wipe test will determine whether the contamination is removable. If the contamination is removable, decontamination of the site should be carried out until he exposure rate is below the trigger level.
78
In the case of a radioactive spill that involves contamination and life-threatening injuries to personnel, which of the following actions should be given priority? (a)decontamination of the victim (b) medical treatment of the seriously injured (c) confinement of the radioactive spill (d) notification of the radiation safety officer (e) establishment of hot and cold zones
(b) Medical treatment for life-threatening conditions ALWAYS takes precedence over any other activity. To prevent the spread of contamination, the victim can be wrapped in a sheet for transport to the treatment area.
79
Nurses caring for 131I therapy patients who require isolation should be advised that the major sources of contamination include the patient's: (a)feces, urine, and blood (b) urine, saliva, and perspiration (c) blood and urine (d) sputum and blood (e) feces and blood
(b) For up to about 1 week after administration of [131I]sodium iodide, iodine that is not bound to thyroid hormone is found in the urine, perspiration, sputum, and saliva. These body fluids are the major sources of contamination from an 131I therapy patient.
80
According to NRC regulations, a technologist cannot use a diagnostic dosage that exceeds 20% of the dosage prescribed by the authorized user unless: (a)There is no other radiopharmaceutical available. (b) The patient weighs more than 20% over the standard reference weight. (c) The authorized user approves the individual dosage. (d) The patient's physician approves the individual dosage. (e) The radiologist or nuclear medicine physician approves the individual dosage.
(c) According to NRC regulations, a dosage cannot be administered if the activity falls outside the range established by the authorized user or differs from the prescribed dosage by 20% or more, unless the authorized user directs the dosage to be administered.
81
If a woman who is breast-feeding needs 131I therapy for treatment of thyroid cancer, how long must she suspend breast-feeding? (a)48 hr (b) 1 week (c) She may not resume it with this child. (d) Suspension of breast-feeding is not necessary in this case. (e) 72 hr
(c) According to the NRC, a woman who is breast-feeding should completely cease breast-feeding after she has received [131I]sodium iodide.
82
According to the NRC, wipe-test results must be reported as: (a)cpm (b) mR/hr (c) dpm (d) mRem/hr (e) mCi/mL
(c) According to the NRC, wipe test results must be reported in dpm.
83
15 mrem is equivalent to how many mSv? (a)0.15 (b) 0.015 (c) 0.0015 (d) 1.5 (e) 15
(a) 1 mRem = 0.01 mSv, therefore 15 x 0.01 mSv = 0.15 mRem
84
A package containing radiopharmaceuticals is delivered before the nuclear medicine department opens. According to the NRC, the package must be checked in and monitored: (a)as soon as the department opens (b) within 3 hr after the department opens (c) within 6 hr after the department opens (d) within 24 hr of the time of delivery (e) within 48 hr of the time of delivery
(b) NRC regulations state that packages containing radioactive material must be monitored no later than 3 hr after delivery during regular working hours or within 3 hr of opening the department for the workday if the package was delivered after hours.
85
``` On the basis of these data: Wipe test count: 375 cpm Background count: 120 cpm and a well counter efficiency of 45%, the results of the wipe test in dpm are: (a)49 dpm ``` (b) 115 dpm (c) 255 dpm (d) 423 dpm (e) 567 dpm
(e) To determine wipe test readings in dpm: dpm = (gross cpm - background cpm) / efficient as a decimal In this example: (375 cpm - 120 cpm) / 0.45 = 567 dpm
86
On the basis of this graph: (measured activity is higher than calculated activity as the activity gets lower) the dose calibrator linearity test results demonstrate that: (a)The instrument consistently gives higher readings than expected. (b) Lower activities are measured as accurately as higher activities. (c) The instrument is operating linearly over the range of activities measured. (d) The instrument should be used to measure only millicurie amounts of radioactivity. (e) The instrument consistently gives lower readings than expected.
(a) The results of this linearity test demonstrate that the measured readings are always higher than the calculated activity (the measured readings line is above the calculated activities line). The difference between measured and calculated activities increases in the lower range of activities. To determine if the instrument is operating within limits according to the standard of practice, the technologist next should determine whether the measured values are within +-10% of the calculated values.
87
``` The calibration of a scintillation spectrometer yielded the following data: Voltage - Net cpm 600 - 8,010 605 - 8,830 610 - 9,543 615 - 10,998 620 - 11,523 625 - 11,175 630 - 10,789 635 - 10,111 640 - 9,514 645 - 8,912 650 - 8,246 What is the operating voltage of this instrument? (a)615 ``` (b) 625 (c) 620 (d) 630 (e) 635
(c) Calibrating a scintillation spectrometer involves the determination of the operating voltage applied to the dynodes of the photomultiplier tub. A reference standard, such as 137Cs, is counted at various voltage settings, and the counts are recorded. The voltage at which the maximum number of counts is obtained is the operating voltage for the instrument. Calibration results are valid ONLY for the gain setting used during the determination of the operating voltage.
88
An energy resolution test is performed on a scintillation spectrometer using 137Cs. If the full width at half maximum (FWHM) is determined to be 53 keV and the photopeak energy is 662 keV, what is the percentage energy resolution of the instrument? (a)0.08% (b) 12.5% (c) 1.3% (d) 8% (e) 25%
(d) The percent energy resolution is calculated using the following formula: % energy resolution = FWHM in keV x 100 / energy of radionuclide in keV In this example: 53 keV x 100 / 662 keV = 8.0%
89
If a dose calibrator linearity test begins by assaying 50 mCi of [99mTc]pertechnetate, for how long should the test be carried out? (a)24 hr (b) 48 hr (c) 72 hr (d) 66 hr (e) 96 hr
(d) The standard of practice calls for a dose calibrator linearity test to be carried out until the original activity is decayed to 30 uCi or less. If the test begins with 50 mCi, it will take 11 half-lives or 66 hr for the original activity to decay to 30 uCi.
90
If a PLES transmission phantom is used, how many images must be acquired to assess linearity over the entire field of view of a scintillation camera? (a)1 (b) 3 (c) 2 (d) 5 (e) 4
(c) A PLES phantom contains lead bars that have the same width and spacing. Two images taken 90 to one another can be used to assess linearity over the entire field of view.
91
According to the NRC, all dose calibrator quality control results must be retained for: (a)1 year (b) 5 years (c) the life of the instrument (d) as long as the facility's license is in effect (e) 3 years
(e) All dose calibrator quality control records must be retained for 3 years.
92
What is the effect of changing the order of a Butterworth filter from 3 to 5? (a)The image will be smoother. (b) The star artifact will be eliminated. (c) The image will appear unchanged. (d) The image will be sharper. (e) The image will be enlarged.
(d) As the order of a Butterworth filter is increased, more high frequencies are retained in the image. High frequencies add sharpness to the image, so the overall image will be sharper. However, much of the data in the high-frequency range result from noise, so retaining the high frequencies may produce a sharper image that is also less representative of the true distribution of activity. Changing the order of a filter results in more-subtle changes in the image than adjusting the cutoff frequency.
93
A 256 x 256 matrix requires how much more computer memory than a 64 x 64 matrix? (a)2 times more (b) 16 times more (c) 8 times more (d) 4 times more (e) 32 times more
(b) A 64 x 64 matrix is made up of 4,096 pixels. A 256 x 256 matrix is made up of 65,536 pixels. To store data in computer memory, a storage location is needed for each pixel. Because the 256 x 256 matrix has 16 times more pixels than the 64 x 64 matrix, it will require 16 times more storage locations in computer memory.
94
Which of the following statements about an image acquired with zoom is true? (a)Image resolution is increased. (b) Background counts are increased. (c) More memory is required. (d) Contrast is decreased. (e) Specificity is increased.
(a) When zoom mode is engaged before acquisition, the image is magnified because a small region of interest is represented by a large number of pixels. This increases resolution. Background is actually decreased. Contrast will be determined by the total counts acquired. The amount of memory required remains the same because the same number of pixels (same matrix size) is being used. They are simply covering a smaller anatomical area.
95
If a [99mTc]medronate bone image and 111In-tagged white blood cell image are acquired simultaneously with a 128 x 128-word mode matrix, how much computer memory is required to store the images? (a)32 kB (b) 16 kB (c) 256 kB (d) 128 kB (e) 64 kB
(e) Each image has to be stored in a separate matrix. Therefore, a set of storage locations in computer memory is needed for each. One 128 x 128 word mode matrix contains 16,384 words or, because there are two bytes per word, 32,768 bytes. Two such matrices require 65,536 bytes. A kilobyte (kB) contains 1,024 bytes. To convert bytes to kB: 65,536 bytes x 1kB / 1024 bytes = 64 kB
96
An uptake probe would be used for which of the following studies? (a)splenic sequestration (b) red cell mass (c) red cell survival (d) plasma volume test (e) liver sequestration
(a) A splenic sequestration study requires external counting over the spleen, liver, and precordium. Using the uptake probe with a flat-field collimator minimizes counts from surrounding tissue and background.
97
How much memory will be needed for a gated-equilibrium cardiac function examination that is acquired in 30 frames with a 128 x 128-byte mode matrix? (a)3,840 bytes (b) 16,384 bytes (c) 49,1520 bytes (d) 546 bytes (e) 256 bytes
(c) The total memory required equals matrix height in pixels x matrix width in pixels x number of frames. In this example, 128 x 128 x 30 = 491,520 bytes. The number of pixels in the acquisition matrix corresponds to the number of memory locations or bytes needed for one frame of data.
98
What energies will be accepted by a 15% window placed around a centerline of 159 keV? (a)135-183 keV (b) 144-174 keV (c) 151-167 keV (d) 147-171 keV (e) 159-189 keV
(d) Half of the percentage of the window is above and half is below the centerline. The window is expressed as a percentage of the energy of the radionuclide. In this case, the window would be 159 keV +- 12 keV because 7.5% of 159 keV equals 12 keV.
99
A SPECT study is acquired using 60 projections over a 360 rotation. Each projection is acquired for 0.5 min. If the counting rate is 144,000 cpm, how many counts will be collected for the total acquisition? (a)1,036,800 (b) 2,587,300 (c) 3,640,000 (d) 3,920,000 (e) 4,320,000
(e) Calculate the total acquisition time: Acquisition time = number of projections x time per projection In this example: 60 projections x 0.5 min/projection = 30 min Calculate total number of counts based on the acquisition time: total counts = acquisition time x counting rate In this example: 30 min x 144,000 cpm = 4,320,000 counts
100
Using a 125 uCi source, 30,500 cpm were collected during a camera sensitivity determination. If the background count is 1200 cpm, what is the sensitivity of the instrument? (a)234 cpm/uCi (b) 244 cpm/uCi (c) 29,300 cpm (d) 3,662,500 cpm (e) 300,500 cpm
(a) Sensitivity is expressed as counts per minute per microcurie. To calculate sensitivity: sensitivity = (source cpm - background cpm) / source activity in uCi In this example: (30,500 cpm - 1200 cpm) / 125 uCi = 234 cpm/uCi

ST Questions (8 decks)

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