ST:5 Flashcards
A [99mTc]oxidronate image of the region shown (ANTERIOR THORAX/PROXIMAL UPPER EXTREMITIES) would demonstrate all of the following structures EXCEPT the:
(a)costochondral junctions
(b) acromion processes
(c) clavicles
(d) sternum
(e) humerus
(b) The diagram depicts an anterior view for the rib cage and proximal upper extremities. The acromion processes would be demonstrated on a posterior view of the upper thorax that includes the scapulae.
For a patient undergoing bone imaging, which of the following information from the medical history is relevant to the interpretation of the bone image?
(a)splenectomy 5 years ago
(b) abdominal surgery 10 days ago
(c) radiation therapy to the breast 6 months ago
(d) gallbladder surgery a year ago
(e) results of previous bone imaging procedures
(e) Results of previous bone imaging procedures performed with nuclear medicine or another imaging modality may provide additional information not demonstrated on the current image or indications that the condition has improved or worsened. Healing soft tissue, such as that resulting from recent abdominal surgery, will concentrate bone tracer in an unexpected area. External beam radiation therapy can cause photopenic areas-areas of decreased tracer activity- on the bone image in the area where the therapy was delivered. All of this information will help the physician explain the findings on a bone image.
If a patient is injected with [99mTc]MAA while in an upright position, which of the following is most likely to be seen on the perfusion lung images?
(a)increased tracer activity in the lung apices
(b) decreased tracer activity in the lung bases
(c) decreased tracer activity in the lung apices
(d) decreased tracer activity throughout both lungs
(e) the heart
(c) If the patient is in the upright position, the apices of the lung receive very little blood flow, Consequently, more MAA particles will be distributed in the bases of the lungs than in the apices. In the supine position, although there is a blood flow gradient from anterior to posterior, there is a more homogeneous distribution of particles from apex to base.
If the usual adult dosage of [99mTc]MAA is 4 mCi, a patient who has had a right pneumonectomy should receive what dosage?
(a)1 mCi
(b) 3 mCi
(c) 2 mCi
(d) 5 mCi
(e) 4 mCi
(c) For an adult patient who has only one lung and, therefore, half the lung vasculature, half the usual dosage is recommended. This reduces the number of particles to approximately half of what is administered in a full dosage.
Which one of the following steps would be appropriate during a standby-assist wheelchair transfer?
(a)The wheelchair should be perpendicular to the imaging table.
(b) The wheelchair footrests should be out of the way.
(c) The wheelchair should be placed parallel to the imaging table.
(d) The wheelchair should be unlocked.
(e) The transfer should take place in the presence of a physician.
(b) The footrests should always be moved out of the way. The wheelchair must be properly aligned to the imaging table (depending on patient condition) and locked.
Patient preparation for infection imaging using tagged white blood cells includes:
(a)fasting for at least 4 hr with a blood glucose level below 120 mg/dL
(b) lab work and information concerning recent blood transfusions
(c) discontinuation of certain medications
(d) smoking cessation for at least 24 hr
(e) fasting for at least 4 hr with a blood glucose level below 200 mg/dL
(b) No special preparation is needed for a white blood cell infection imaging other than a possible interference if the patient has had a recent blood transfusion.
Thyroid imaging may be performed with which of the following collimators?
(a)flat field
(b) pinhole
(c) parallel hole
(d) pinhole or parallel hole
(e) slant hole
(d) A pinhole collimator provides an image with better resolution and offers the ability to obtain oblique views. A parallel-hole collimator used with electronic zoom can provide a magnified image with good resolution.
In performing a thyroid uptake, a technologist collects the thyroid counts 5 cm from the surface of the patient’s neck and the standard counts 20 cm from the surface of the neck phantom. What is the effect on the thyroid uptake value calculated from this data?
(a)The uptake value will be falsely increased.
(b) The uptake value will be falsely decreased.
(c) The uptake value will be accurate.
(d) The results are unpredictable.
(e) There is no effect.
(a) Recall that, as a point source is moved closer to the face of a flat-field collimator, more counts are collected. If the standard represents the total amount of activity administered to the patient, the counts collected from the patient’s neck represent a portion of the total amount of activity that concentrated in the thyroid gland. It is important, therefore, based on the response of the detector at a given distance, to count both the standard and the patient at the same distance. For example, suppose the standard and the patient were both counted at 20 cm, and 20,000 net cpm and 5,000 net cpm were obtained, respectively. The patient’s uptake is:
neck counts x 100 / standard counts = 5000 cpm x 100 / 20,000 cpm = 25%
If the patient were counted at 5 cm instead of 20 cm, more counts would be collected (i.e., 10,000 cpm). Then, the patient’s uptake is falsely increased:
neck counts x 100 / standard counts = 10000 cpm x 100 / 20,000 cpm = 50%
The percentage left ventricular ejection fraction calculated from the net counts per minute shown here: End diastole: 2875 End systole: 2162 is approximately: (a)25%
(b) 13%
(c) 33%
(d) 100%
(e) 75%
(a) The counts per minute are obtained from the regions of interest drawn around the end-diastolic and end-systolic images. The counts in each region are then corrected for background. The formula for calculating the left ventricular ejection fraction is:
LVEF = (net end-diastolic counts - net end-systolic counts) x 100 / net end-diastolic counts
= (2875 cpm - 2162 cpm) x 100 / 2875 cpm = 25%
When a technologist cares for a patient who is not known to have a communicable disease, all of the following infection control measures should be implemented EXCEPT:
(a)wearing gloves when collecting a blood sample
(b) decontaminating imaging equipment with an antiseptic
(c) handwashing before and after the nuclear medicine examination
(d) using a needle recapping device
(e) maintaining aseptic technique when administering the radiopharmaceutical
(b) Standard precautions should be used routinely with all patients. These precautions include activities such as hand washing, wearing gloves, and recapping needles using a safety device. Decontaminating imaging equipment would be performed only if it came in contact with biological fluids from a patient or with a patient known to be infected with a communicable disease.
Normal sinus rhythm is characterized by which of the following? I. 60-100 beats/min II. R wave occurs at constant intervals III. PR interval 0.12-0.20 sec long (a)I and II only
(b) I and III only
(c) II and III only
(d) I, II, and III
(e) III only
(d) the characteristics of normal sinus rhythm as they appear on an ECG tracing are: (1) heart rate of 60-100 beats per minute, (2) R waves at regular intervals (variance of less than 0.12 sec), (3) P waves present and precede QRS complex, (4) PR interval between 0.12 and 0.20 sec long, and (5) QRS complex less than 0.12 sec.
After stress myocardial imaging with [201Tl]thallous chloride, 1-1.5 mCi of [201Tl]thallous chloride may be administered before rest myocardial imaging to:
(a)improve patient throughput
(b) demonstrate reversible ischemia more readily
(c) demonstrate infarct size more precisely
(d) minimize visualization of attenuation artifacts
(e) maximize visualization of attenuation artifacts
(b) Defects visualized on stress images are interpreted as myocardial ischemia if the defects fill in on the resting images. However, the rate of redistribution varies, and ischemic areas may not appear to have re-perfused by 4 hr. Administering a second, smaller dose of 201Tl before rest imaging provides additional tracer in the circulation that can be extracted into there areas, improving the image quality and identifying reversible ischemia.
If the gallbladder is not visualized within 60 min during hepatobiliary imaging, which of the following may be administered?
(a)cimetidine
(b) morphine
(c) dobutamine
(d) furosemide
(e) adenosine
(b) If the gallbladder is not visualized after 1 hr but tracer is seen in the common bile duct and small intestine, morphine may be administered. Morphine acts on the sphincter of Oddi, causing it to contract, thus increasing pressure in the common bile duct and causing tracer to flow into the gallbladder.
Preparation of the patient for Meckel’s diverticulum localization includes:
(a)administration of laxatives
(b) oral or intravenous hydration
(c) an enema immediately before imaging
(d) fasting for at least 2 hr before imaging.
(e) an enema immediately after imaging
(d) Bowel preparations are contraindicated before Meckel’s diverticulum imaging because they irritate the intestinal mucosa, possibly causing a false-positive finding. It is recommended that patients fast for at least 2 hr before imaging to reduce stomach secretions that cause migration of [99mTc]pertechnetate from the stomach into the bowel.
Which of the following 99mTc-labeled agents is the preferred tracer for demonstrating intermittent gastrointestinal bleeding?
(a)human serum albumin
(b) lidofenin
(c) red blood cells
(d) sulfur colloid
(e) macro aggregated albumin
(c) Because [99mTc]sulfur colloid is cleared from the blood within 10-15 min after administration, it is preferred when the patient exhibits active gastrointestinal (GI) bleeding. In cases where the GI bleeding is intermittent and unpredictable, 99mTc-labeled red blood cells are preferred, because this tracer remains in the blood pool for an extended period that permits imaging up to 24 hr.
Furosemide is sometimes administered during renal imaging to:
(a)Rule out transplant rejection.
(b) Increase blood flow to the kidneys.
(c) Enhance tracer uptake in an abnormal kidney.
(d) Rule out ureteropelvis obstruction.
(e) Decrease blood flow to the kidneys.
(d) Furosemide is a diuretic that increases the production. Activity retained in the collecting system or renal pelvis may indicate an obstruction in that area. Furosemide is used to wash out the activity with an increased production of urine. If the activity clears after the administration of furosemide, there is no obstruction.
Which of the following events is a normal response when furosemide is administered near the end of a renal function study?
(a)The peak transit time of the radiopharmaceutical is elongated.
(b) Radioactivity is taken up into the renal cortex.
(c) Mechanical blockages in the renal collecting system are cleared.
(d) The peak transit time of the radiopharmaceutical is shortened.
(e) Radioactivity is cleared from the renal pelvis into the bladder.
(e) Furosemide is a diuretic that increase the production of urine. Activity retained in the collecting system or renal pelvis may indicate an obstruction in that area. Furosemide is used to wash out the activity with an increased production of urine. If the activity clears after the administration of furosemide, there is no obstruction. Clearance of the activity is the normal response.
Early (6 hr after injection) 67Ga imaging should be performed if which of the following conditions is suspected?
(a)sarcoma
(b) osteomyelitis
(c) lymphoma
(d) bronchogenic carcinoma
(e) chrondrosarcoma
(b) 67Ga imaging can be performed form 6 hr to 3 days or longer after tracer administration. When the examination is being performed for evaluation of an inflammatory process, early imaging (6 hr after injection) is indicated.
The most effective way of controlling the spread of infectious disease in a hospital setting is for the technologist to:
(a)Wash hands both before and after patient contact.
(b) Wear gloves, mask, and hospital gown at all times.
(c) Stay home when ill.
(d) Maintain distance from each patient.
(e) Always wear a face mask.
(a) It is widely accepted that hand washing is considered to be the single most-effective way of preventing the spread of infection in a medical care facility.
[111In]Pentetreotide normally localizes in all of the following sites EXCEPT:
(a)pituitary gland
(b) salivary glands
(c) spleen
(d) thyroid gland
(e) liver
(b) [111In]pentetreotide normally localizes in the pituitary gland, thyroid gland, liver, spleen, bladder, and bowel.
SPECT brain imaging may begin how soon after the administration of [99mTc]exametazime?
(a)immediately
(b) 1-2 hr
(c) 15-20 min
(d) 24 hr
(e) 48 hr
(b) For the best image quality, brain imaging with [99mTc]exametazime should begin no sooner than 90 min after the administration of the tracer.
Radioactivity is visualized in all of the following areas during a normal cisternographic study EXCEPT the:
(a)cerebral convexities
(b) basal cisterns
(c) central canal
(d) lateral ventricles
(e) subarachnoid space
(d) Normally, cerebral spinal fluid flows out of the lateral ventricles. Reversal of this flow (or reflux) and visualization of tracer in the lateral ventricles is an abnormal finding.
Patient preparation for instilling colloidal [32P]chromic phosphate into the peritoneal cavity includes which of the following?
(a)surgical placement of a LeVeen shunt to remove excess peritoneal fluid
(b) fasting for 8-12 hr before radiopharmaceutical administration
(c) instructing the patient about isolation requirements
(d) introducing [99mTc]sulfur colloid into the cavity to confirm that the 32P will disperse evenly
(e) administering an antacid 2-4 hours before the procedure
(d) Before instilling 32P into the peritoneal space, [99mTc]sulfur colloid is introduced to demonstrate that the agent will disperse throughout the cavity, thereby uniformly irradiating the peritoneal space.
Patient preparation for post-thyroidectomy 131I whole-body imaging for metastases may include all of the following EXCEPT:
(a)administration of 600-1000 mg of potassium perchlorate 2 hr before imaging
(b) administration of exogenous TSH
(c) discontinuation of replacement thyroid hormone
(d) following a low-iodine diet for 1-2 weeks before imaging
(e) no IV CT contrast 6 weeks before
(a) After a thyroidectomy, the purpose of 131I whole-body imaging is to detect the presence of residual thyroid tissue and/or distant metastases. To enhance the visualization of any metastases, the patient may be instructed to limit dietary iodine. The patient may also discontinue replacement thyroid hormone therapy to permit the metastases to function as thyroid tissue. Exogenous TSH may also be prescribed to stimulate the metastases to concentrate iodine.
The administration technique for [99mTc]bicisate includes which of the following?
(a)direct venous stick
(b) infusion at peak cardiac stress
(c) bolus injection technique
(d) infusion over 3 hours
(e) minimize environmental stimuli
(e) It is desirable to image the brain in as close to a “resting” state as possible. Because uptake of [99mTc]bicisate can be affected by sensory input, distractions (bright lights, noise, pain) should be kept to a minimum.
Which of the following instructions should be given to patients after administration of [18F]FDG for PET imaging?
(a)The patient may leave the imaging area and return in approximately 90 min.
(b) The patient should rest quietly in a designated waiting area until imaging begins.
(c) The patient may read or watch television until imaging begins.
(d) The patient should consume a fatty meal to clear excess tracer from the hepatobiliary system.
(e) The patient should exercise in place for 15 minutes before the start of imaging.
(b) Patients who receive [18F]FDG for PET imaging must remain quiet during the interval between tracer administration and imaging. Small changes in tissue metabolism can cause uptake in skeletal muscle that may obscure or be mistaken for disease or can decrease the amount of tracer taken up into the tumor.
In performing a gastric-emptying study, imaging should begin:
(a)15 min after meal consumption, then every 15 min for 1 hr
(b) immediately after meal consumption, then every 15 min for at least 2 hr
(c) immediately after meal consumption, then every 5 min for at least 1 hr
(d) 1 hr after meal consumption, then every 15 min for the next hour
(e) 2 hr after meal consumption, then every 15 min for at least 2 hrs
(b) With the patient upright, imaging should begin immediately after meal consumption for 1 min, then every 15 min for at least 2 hr. Imaging may need to be extended beyond 2 hr if it appears that the stomach is not emptying.
A patient with a chest tube arrives in the nuclear medicine department for an imaging study. The technologist should:
(a)Place the chest tube’s external apparatus on a level lower than the patient’s chest.
(b) Cancel the procedure because chest tube apparatus will interfere with the study.
(c) Place the chest tube’s external apparatus on the imaging table next to the patient.
(d) Hang the chest tube’s external apparatus from an IV pole and raise it above the patient’s chest.
(e) Drain the chest tube while holding in place during the imaging procedure.
(a) For proper drainage, the chest tube apparatus must always remain lower than the patient’s chest.
Where is the x-ray generator located in a CT scanner?
(a)under the patient imaging table
(b) inside the operator’s console
(c) inside the gantry
(d) inside the electronics cabinet
(e) inside the computer workstation
(c) The gantry houses the key components of the scanner: the x-ray tube, the detector array, the power generator, and the data acquisition system.
To help clear the thyroid, liver, and bowel when performing a cardiac perfusion study with sestimibi, a technologist should give what before imaging?
(a)a fatty meal
(b) dobutamine
(c) dextrose intravenously
(d) adenosine
(e) a glass of cold water
(e) The sestamibi pharmaceutical for cardiac imaging concentrates in multiple organs and can affect the image. In an effort to clear activity out of the thyroid, liver, and lower, cold water can be given to the patient prior to imaging to increase the target:non-target ratio for imaging the heart.
A contraindication for performing a myocardial perfusion resting study is:
(a)fasting for 4-12 hr before the study
(b) drinking cold water before the study
(c) having a normal sinus rhythm
(d) being NPO for 4-12 hr before study
(e) having a nitroglycerin drip
(e) A nitroglycerin drip will interferer with determining if, at rest, the cardiac arteries are partially occluded. (Patients suffering from angina could be on nitroglycerin therapy.)
A post-surgery patient is in the nuclear medicine department for a study. The technologist notices that the patient’s surgical dressing shows signs of drainage. The most appropriate action for the technologist is to:
(a)Reinforce the dressing with additional gauze and notify the appropriate medical personnel.
(b) Remove the old dressing and replace it with a fresh one.
(c) Terminate the study and transport the patient back to his/her room.
(d) Complete the nuclear medicine procedure and ignore the dressing.
(e) Remove the dressing and drain the wound.
(a) The technologist should report the drainage and reinforce the original dressing with additional dressing until appropriate medical personnel are available to address the patient’s needs.
If the hematocrit is 40% and a plasma-volume determination, performed with [125I]-human serum albumin, is 3,900 mL, what are the derived red cell and whole blood volumes, in milliliters?
Red cell volume (mL) - Whole blood volume (mL)
(a)1,560 - 2,340
(b) 2,340 - 6,240
(c) 5,850 - 9750
(d) 2,600 - 6,500
(e) 6,500 - 2,340
(d) The red cell and whole blood volumes can be calculated from the measured plasma volume (PV) using the following formulas:
total blood volume (TBV) = PV (mL) x 100 / (1 - HCT)
TBV = 3900 mL x 100 / (1 - 0.40)
red cell volume = TBV - PV
= 6500 mL - 3900 mL
= 2600 mL
During a red blood cell survival study, the first blood sample is taken 24 hr after the injection of the labeled cells. This 24 hr time period is needed to allow:
(a)the radiochromium to decay to a level compatible with the scintillation detector
(b) patient recovery from the radiopharmaceutical injection
(c) removal of any cells damaged during the labeling process
(d) uniform mixing of the labeled cells throughout the vascular system
(e) a better non-target ratio
(c) The time span between injection and blood sampling allows the body to remove cells damaged during the labeling process and allows free chromic ions to be removed for the plasma.
If an anticoagulant is added to a blood sample, the fluid portion of the blood sample is know as:
(a)serum
(b) plasma
(c) antiserum
(d) blood complement
(e) clotting factor
(b) Preventing clot formation with the addition of an anticoagulant will result in the fluid portion remaining as plasma. The fluid portion of a blood sample that has been allowed to clot is serum.
In a hospital setting, CPR CANNOT legally be administered to a patient in cardiac arrest when the:
(a)patient has an infectious disease
(b) patient’s spouse or significant other indicates their wishes
(c) patient is hallucinating
(d) patient’s chart indicates a terminal illness
(e) patient’s chart indicates DNR
(e) CPR should always be administered to a patient in cardiac arrest unless the patient, patient’s family, or patient’s physician has specifically requested that it not be done. In these cases, DNR (Do Not Resuscitate) or “allow natural death” should be clearly indicated on the patient’s chart.
Pentagastrin is commonly used in which of the following scans:
(a)gastric emptying
(b) deep vein thrombosis
(c) Meckel’s diverticulum
(d) LeVeen shunt patency
(e) myocardial perfusion imaging
(c) Pentagastrin stimulates ectopic gastric mucosal uptake of pertechnetate by 30%-60& while decreasing emptying time into small bowel and decreasing background.
Data collected from a red cell survival procedure are plotted on what type of graph paper?
(a)semilog
(b) linear
(c) log-log
(d) logit-log
(e) logit-logit
(a) Red cell survival half-time is obtained from a graph of the net counts per minute of each blood sample plotted on the log scale and time plotted on the linear scale of semi-log paper.
Which of the following is NOT recommended DURING HMPAO/ECD administration?
(a)Dim the lights.
(b) Inject using an IV line.
(c) Talk calmingly to the patient while injecting.
(d) Ask the patient to keep eyes and ears open.
(e) Let the patient rest for 10 minutes before injection.
(c) Place patient in quiet environment before injection.
If a 1:50 dilution of a solution with a tracer concentration of 50 uCi/mL is prepared, followed by a 1:200 dilution of the 1:50 dilution, what is the final dilution?
(a)1:20
(b) 1:50
(c) 1:1,000
(d) 1:10
(e) 1:10,000
(e) When multiple dilutions are performed, the final dilution is the product of the individual dilutions. Thus:
(1/50) x (1/200) = 1/10000
Which of the following medical history is relevant to [111In]capromab pendetide imaging?
(a)breast-feeding schedule
(b) mammogram results
(c) last menstrual cycle
(d) pregnancy status
(e) PSA level
(e) [111In]capromab pendetide is used in patients who have been newly diagnosed with prostate cancer to more accurately stage the disease before surgery. After surgery or radiation therapy, it is also used to detect recurrence or residual cancer in patients with rising PSA levels but no other evidence of disease.
On the basis of these data shown: Total counts - No. pixels Cardiac ROI - 28,503 - 417 Background ROI - 1,859 - 88 what are the net counts in the cardiac region of interest? (a)28,065
(b) 19,694
(c) 26,644
(d) 15,463
(e) 14,652
(b) Net counts are determined using a background (bkg) region of interest (ROI) drawn near the area of interest. The average counts per pixel in the bkg ROI are subtracted from the cardiac ROI, adjusted for the size of the region.
net cardiac ROI counts = cardiac ROI counts - ((bkg ROI counts / bkg ROI pixels) x cardiac ROI pixels)
28,503 cts - (1859 cts / 88 pixels) x 417 pixels
28,503 cts - (21 cts/pixel x 417 pixels)
28,503 cts - 8809 cts = 19,694 cts
If a 99Mo/99mTc generator is eluted at 0700 and again at 1300, the next day’s 99mTc yield at 0700:
(a)will be unaffected
(b) will be decreased
(c) will be increased
(d) cannot be predicted
(e) will be uniform
(b) The yield of 99mTc is affected by three factors: the amount of 99Mo on the column at the time of elution, the time elapsed since the last elution, and the elution efficiency of the generator. The shorter the time between elutions, the less time the 99Mo has to decay to 99mTc, resulting in a lower yield of 99mTc.
127 millicuries is equivalent to how many gigabecquerels?
(a)0.003 GBq
(b) 4699 GBq
(c) 3430 GBq
(d) 4.70 GBq
(e) 4925 GBq
(d) Conversions between the CGS and SI systems can be accomplished easily if you remember the three following relationships: 1 Ci = 37 GBq 1 mCi = 37 MBq 1 uCi = 37 kBq Then, to convert millicuries to gigabecquerels: 127 mCi x 37 MBq/mCi = 4699 MBq 1000 MBq = 1 GBq 4699 MBq x 1 GBq/1000MBq = 4.7 GBq
All of the following factors affect the amount of 99mTc eluted from a 99Mo/99mTc generator EXCEPT:
(a)the amount of 99Mo activity present on the column
(b) the time elapsed since the last elution
(c) the elution efficiency of the generator
(d) the time elapsed since calibration
(e) the saline volume used for elution
(e) The amount of 99mTc activity removed will be the same regardless of the saline volume used for elution. However, the amount of 99Mo on the column, the time elapsed since the last elution, and the elution efficiency of the generator all influence the amount of 99mTc activity eluted.
According to the NRC, the maximum allowable 99Mo concentration in 99mTc eluate at the time of administration to the patient must not exceed:
(a)5 uCi 99Mo/mCi 99mTc
(b) 1 uCi 99Mo/mCi 99mTc
(c) 0.15 uCi 99Mo/mCi 99mTc
(d) 5 uCi in a unit dose
(e) 0.10 uCi 99Mo/mCi 99mTc
(c) 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.
An eluate of [99mTc]pertechnetate is assayed for 99Mo contamination with the following results:
99Mo: 45 uCi
99mTc: 275 mCi
On the basis of this assay, the technologist should:
(a)Wait for the 99Mo to decay to an acceptable level.
(b) Use the eluate only for studies requiring other 99mTc-labeled agents.
(c) Discard the eluate.
(d) Use the eluate for only the next 12 hr.
(e) Wait for the 99mTc to decay to an acceptable level.
(c) The 99Mo concentration in this eluate is equal to:
45 uCi / 275 mCi = 0.16 uCi 99Mo/mCi 99mTc
This 99Mo concentration exceeds the maximum allowable limit of 0.15 uCi 99Mo/mCi 99mTc set by the NRC. Therefore, the technologist must not administer the eluate to patients either as [99mTc]pertechnetate or as some other 99mTc-labeled compound. Also, remember that radionuclide purity changes with time. Because 99Mo (T1/2 = 66 hr) decays more slowly than 99mTc (T1/2 = 6 hr), the ratio of 99Mo to 99mTc will increase with time, exceeding the maximum allowable limit to a greater extent.
If a new generator is eluted several times and each time the amount of aluminum in the eluate exceeds the USP limit, the technologist should:
(a)Contact the generator manufacturer.
(b) Use the eluate for patients.
(c) Increase the elution volume.
(d) Prepare kits with an additional oxidation agent.
(e) Prepare the kit with an additional reducer agent.
(a) High levels of aluminum ions in 99mTc eluate can affect the preparation of radiopharmaceuticals and change their biodistribution, including the distribution of [99mTc]pertechnetate. Therefore, eluate with an aluminum ion concentration exceeding the USP limit should not be administered to patients or be used to prepare other 99mTc-labeled tracers. High levels of aluminum ions indicate a defect in the preparation of the generator’s alumina column, a problem that cannot be corrected on site in the clinical setting. The manufacturer should be notified, and the generator should be returned for replacement.
Which of the following 99mTc-labeled agents is approved for perfusion brain imaging?
(a)apcitide
(b) exametazime
(c) succimer
(d) tetrofosmin
(e) medronate
(b) [99mTc]apcitide is used to visualize acute deep vein thrombosis in the lower extremities. [99mTc]succimer is a static renal imaging agent. [99mTc]exametazime (HMPAO) is a radiopharmaceutical approved for perfusion brain imaging. [99mTc]tetrofosmin is a myocardial perfusion agent.
The shelf-life of most 99mTc-labeled radiopharmaceuticals is:
(a)4-6 hr
(b) 18-24 hr
(c) 10-12 hr
(d) 16-18 hr
(e) 6-8 hr
(e)A review of radiopharmaceutical kit package inserts shows that most prepared 99mTc agents may be administered for 6-8 hr after preparation. Some exceptions include [99mTc]succimer, which must be administered within 30 min, and [99mTc]pentetate, which, when used for glomerular filtration rate determination, must be administered within 1 hr of preparation.
If the following reagents are available: Disofenin kit Maximum 99mTc activity to be added: 100 mCi Reconstituting volume: 0.5-3.0 mL [99mTc]pertechnetate Concentration: 25.0 mCi/mL Total volume: 8.0 mL What volume of [99mTc]pertechnetate must be added to the kit to prepare the maximum amount of [99mTc]disofenin from one kit? (a)3.0 mL
(b) 4.0 mL
(c) 8.0 mL
(d) 2.5 mL
(e) 1.5 mL
(a) Based on the activity and volume limits for the kit, up to 100 mCi may be prepared using a volume of 0.5-3.0 mL [99mTc]pertechnetate. Using the maximum reconstituting volume, 75 mci of [99mTc]disofenin can be prepared, an amount within both the volume and activity limits of the kit:
3. 0 mL x 25.0 mCi/mL = 75.0 mCi
One advantage of the in vivo method of 99mTc red cell tagging is that:
(a)No manipulation of blood samples outside the body is required.
(b) No incubation times are required at any step in the process.
(c) All circulating red cells are labeled with tracer.
(d) Smaller amounts of stannous chloride are required.
(e) White blood cells do not interfere in the process.
(a) The major advantage of in vivo red cell labeling is that tagging takes place in the circulatory system. The patient first receives reconstituted “cold” pyrophosphate containing stannous ion that permits [99mTc]pertechnetate to permeate red cell membranes. After a short incubation period to allow the stannous ion to come into contact with the red cells, the patient is injected with [99mTc]pertechnetate. After another short incubation period when the tracer becomes incorporated in the red cells, imaging begins.
Boiling a [99mTc]sulfur colloid preparation for too long will result in colloidal particles that are:
(a)too small
(b) clumpy
(c) optimal size
(d) chemically unstable
(e) too large
(e) The diameter of the colloid particle is increased as a function of heating time. Thus, the longer the 99mTc preparation is heated, the larger the sulfur colloid particles become. Extended heating times, beyond what is recommended in the package insert, result in particles large enough to become trapped in the lung vasculature.
Which of the following components in a [99mTc]medronate preparation is a radiochemical impurity?
(a)aluminum
(b) 99Mo
(c) 0.9% NaCl
(d) [99mTc]pertechnetate
(e) ascorbic acid
(d) Radiochemical purity is defined as the fraction of total radioactivity present in the desired chemical form, in this case, [99mTc]medronate. [99mTc]pertechnetate that did not bind to the ligand, medronate, is a radiochemical impurity. Aluminum is a chemical impurity. 99Mo is a radionuclidic impurity. It is a radionuclide other than the desire one, 99mTc.
Which of the following image findings is most consistent with chromatography results of a [99mTc]oxidronate sample demonstrating 65% radiochemical purity?
(a)well-defined bone uptake
(b) stomach and thyroid uptake
(c) lung uptake
(d) gastrointestinal tract activity
(e) heart uptake
(b) The radiochemical purity of the radiopharmaceutical is only 65%. Tagging efficiencies (radiochemical purities) of 90% or greater contribute to technically satisfactory images. The large amount of impurity (35%), most of which is likely to be free pertechnetate, will be demonstrated as uptake in areas of the body known to concentrate [99mTc]: the salivary and thyroid glands, and the gastric mucosa of the stomach.
If 740 kBq of a radiopharmaceutical is to be administered for each kilogram of body weight, approximately how much activity (in megabecquerels) should be administered to a patient who weighs 172 pounds?
(a)9.5 MBq
(b) 652 MBq
(c) 78 MBq
(d) 280 MBq
(e) 58 MBq
(e) First convert the patient’s body weight into kilograms:
172 lbs x kg/2.2lbs = 78kg
Next, calculate the total activity to be administered to the patient based on body weight:
78 kg x 740 kBq/kg = 57,720 kBq
Then, convert kBq into MBq.
57,720 kBq x MBq/1000 kBq = 58 MBq
If 50 millicuries of [99mTc]MAA are available at 0700, how many lung perfusion imaging studies can be performed if the administered dose is 5 mCi and one patient is injected every hour begining at 0730?
(a)10
(b) 7
(c) 6
(d) 20
(e) 15
(c) If all patients were being injected at 0700, the maximum number of studies that could be performed is 10 (50 mCi / 5 mCi/patient = 10 patients). However, the injections are beginning at 0730 and on each half hour thereafter. Therefore, the available activity must be decay corrected fro 0730 and for each injection thereafter. (See chart.)
Patient - Time - Decay-corrected Activity Available (mCi) - Unit Dosage (mCi) - Activity Remaining (mCi)
1 - 0730 - 50 mCi x 0.946 = 47.3 - 5 - 42.3
2 - 0830 - 42.3 mCi x 0.891 = 37.7 - 5 - 32.7
3 - 0930 - 32.7 mCi x 0.891 = 29.1 - 5 - 24.1
4 - 1030 - 24.1 mCi x 0.891 = 21.5 - 5 - 16.5
5 - 1130 - 16.5 mCi x 0.891 = 14.7 - 5 - 10.0
6 - 1230 - 10.0 mCi x 0.891 = 8.6 - 5 - 3.6
For cardiac first-pass studies, the prescribed adult dosage of [99mTc]pentetate if 925 MBq +-10%. On the basis of the vial label information shown here for [99mTc]pentetate, what is the maximum volume that should be administered to the patient at 0800 on January 5? Total activity: 3.7 GBq Total volume: 2.0 mL Concentration: 1.85 GBq/mL Calibration: 0600, January 5 (a)0.57 mL
(b) 0.63 mL
(c) 1.0 mL
(d) 0.69 mL
(e) 1.3 mL
(d) The elapsed time between calibration and dosage administration is 2 hr (0600-0800). Decay-correct the initial concentration for 2 hr using the appropriate decay factor for 99mTc:
1.85 GBq/mL x 0.794 = 1.47 GBq/mL
Then, determine the maximum volume that can be administered to the patient. The maximum prescribed activity, 925 MBq + 92.5 MBq or approximately 1,017 MBq, will make up the maximum volume. Remember that the concentration and the required activity must be expressed in the same units. Changing the required activity to GBq:
1017 MBq x GBq/1000 Bq = 1.02 GBq
volume = activity required C(t)
= 1.02 GBq / 1.47 GBq/mL
= 0.69 mL
In labeling red blood cells with 51Cr, the final step before re-injecting the labeled red blood cells into the patient is to:
(a)Add ascorbic acid to the tagged blood.
(b) Wash the labeled red cells to remove excess 51Cr.
(c) Separate the red blood cells from the plasma.
(d) Add 51Cr to the patient’s blood sample.
(e) Seperate the white blood cells from the plsama.
(a) Ascorbic acid is added after red cell tagging has occurred but before the tagged sample is reinjected into the patient. Ascorbic acid reduces any untagged 51Cr in the hexavalent state to a trivalent state, thus preventing red cell tagging in vivo after reinjection.
In what way does the modified in vivo method of labeling red blood cells with [99mTc]pertechnetate differ from the in vivo method?
(a)The modified method requires a smaller amount of stannous pyrophosphate.
(b) The modified method “pretins” only a small volume of the patient’s blood.
(c) The modified method uses a smaller activity of [99mTc]pertechnetate.
(d) The modified method mixes [99mTc]pertechnetate with only a small volume of the patient’s blood.
(e) The modified method requires a larger amount of stannous pyrophosphate.
(d) In both the in vivo and modified in vivo methods of labeling red blood cells with [99mTc]pertechnetate, reconstituted stannous pyrophosphate is injected intravenously into the patient. Hence, the same amount of stannous pyrophosphate is administered, and the entire volume of the patient’s blood is “pretinned” in either method. Both methods use 20 to 30 millicuries of [99mTc]pertechnetate. The main difference in the modified in vivo method is that only a small volume (~3 mL) of the patient’s pretinned blood is mixed with [99mTc]pertechnetate in a syringe. In the in vivo method, [99mTc]pertechnetate is injected intravenously 15-30 min after stannous pyrophosphate.
Which of the following statements about the modified in vivo method for labeling red blood cells with [99mTc]pertechnetate is TRUE?
(a)Only a sample of the patient’s blood is incubated with the reconstituted stannous pyrophosphate.
(b) Red cell labeling takes place only within the patient’s circulatory system.
(c) A sample of the patient’s “pretinned” blood is incubated with [99mTc]pertechnetate outside of the patient.
(d) Excess [99mTc]pertechnetate is removed from the blood sample before the sample is re-injected into the patient.
(e) A larger amount of stannous pyrophosphate is used.
(c) The modified in vivo method for labeling red blood cells involves first administering “cold” stannous pyrophosphate to the patient. Then, a small sample (1-5 mL) of the patient’s blood is incubated with [99mTc]pertechnetate outside the patient. The in vitro method involves collecting a small blood sample that is first incubated with stannous ion, then [99mTc]pertechnetate outside the patient. The plasma containing unbound [99mTc]pertechnetate is removed and the red cells washed before reinjecting them. In the in vivo method, all labeling steps occur within the patient.
According to NRC regulations, which of these unit dosages may be administered to the patient? Prescribed dosage (mCi) - Measured dosage (mCi) (a)10 - 13.5
(b) 15 - 12.5
(c) 8-10 - 10.9
(d) 20-25 - 18.7
(e) 25 - 30
(b) The NRC states that the administered dosage must fall within the prescribed dosage range or may not differ from the prescribed dosage is 10 mCi, the measured dosage must be between 8 and 12 mCi (+-20% of 10 mCi). The measured dosages in choices c and d fall outside the prescribed dosage ranges. Choice b is the correct answer because 12.5 mCi falls within +-20% of 15 mCi.
In the radiochromium labeling process, ascorbic acid is used as which of the following?
(a)reducing agent
(b) radiotracer
(c) oxidizing agent
(d) anticoagulant
(e) neutralizing agent
(a) Ascorbic acid reduces the valence of any remaining free chromium from +6 to +3. The purpose of this step is to stop the red cell tagging process before the labeled blood is reinjected into the patient.
If a vial of 99mTc-labeled radiopharmaceutical contains 4.65 MBq in 3.5 mL at 0800, what is the concentration at 0930?
(a)1.12 MBq/mL
(b) 1.33 MBq/mL
(c) 0.90 MBq/mL
(d) 0.75 MBq/mL
(e) 0.52 MBq/mL
(a) Decay-corrected the activity for 1.5 hr (0800-0930) using the 1.5-hr decay factor for 99mTc:
4.65 MBq x 0.84 = 3.91 MBq
Determine the concentration at 0930 using the decay corrected activity:
concentration = total activity / total volume = 3.91 MBq / 3.5 mL = 1.12 MBq/mL
If a unit dosage of [99mTc]pertechnetate is calibrated to contain 25 mCi in 0.8 mL at 1400, what volume should be removed from the syringe to retain 15 mCi in the syringe at 1200?
(a)0.20 mL
(b) 0.32 mL
(c) 0.52 mL
(d) 0.48 mL
(e) 0.42 mL
(e) First, determine the total activity in the syringe at 1200 by backdecay-correcting the activity using the 2-hr decay factor (1200-1400 = 2 hr) for 99mTc:
25 mCi / 0.794 = 31.5 mCi
Then, determine the concentration at 1200:
concentration = total activity / total volume = 31.5 mCi / 0.8 mL = 39.4 mCi/mL
Determine the volume that will contain 15 mCi at 1200:
volume = activity required / concentration = 15 mCi / 39.4 mCi/mL = 0.38 mL
Determine the volume that will have to be removed from the syringe:
total - volume required = volume to be removed
0.8 mL - 0.38 mL = 0.42 mL
If an MAA kit containing 4.5 million particles is prepared by adding 30 mCi in 2.5 mL, how many particles are contained in 3 mCi?
(a)150,000
(b) 180,000
(c) 450,000
(d) 215,000
(e) 555,000
(c) Based on the volume added to the kit, determine the number of particles in 1 mL:
4.5 million particles / 2.5 mL = 1.8 million particles/mL
Determine the kit concentration:
concentration = total activity / total volume = 30 mCi / 2.5 mL = 12 mCi/mL
Determine the volume that will contain the required activity:
volume = activity required / concentration = 3 mCi / 12 mCi/mL = 0.25 mL
Determine the number of particles contained in the patient dosage:
dosage volume x particles/mL = particles in patient dosage
0.25 mL x 1.8 million particles/mL = 450,000 particles
Note that the number of particles in the patient dosage is within the recommended range for adults.
Of the following syringes, which size would be best for withdrawing 1 mL of radiopharmaceutical from a multi-dose vial?
(a)3 mL
(b) 1 mL
(c) 5 mL
(d) 20 mL
(e) 10 mL
(a) The syringe size is the next size larger than the volume to be withdrawn. If the syringe is filled to its maximum volume, the plunger may easily be pulled out while a volume is being withdrawn or while a patient is being injected with the volume in the syringe.
According to NRC regulations, which of the following signs should be posted in unrestricted areas?
(a)”Caution: Radioactive Materials”
(b) “Authorized Personnel Only”
(c) No posting is required.
(d) “Caution: Radiation Area”
(e) “Caution: High Radiation Area”
(c) According to the NRC, an unrestricted area is one in which access is not limited by or under control of a license. Unrestricted areas are not posted.
A package containing radioactive material is monitored and found to produce 12 mR/hr at the surface and 0.9 mR/hr at 1 m from the surface. Which DOT label must be affixed to the outside of the package?
(a)”Category II”
(b) “Category I”
(c) “Category IV”
(d) No DOT label is required.
(e) “Category III”
(a) The label types and exposure rate limits for packages containing radioactive material are: Label category - At surface - At 1 m Category I (white) - <=0.5 - No detectable radiation Category II (yellow) - <=50 - <= 1.0 Category III (yellow) - <=200 - <= 10
According to the NRC, decay in storage records must include the date that the radioactive material was:
(a)calibrated
(b) received
(c) placed in storage
(d) disposed
(e) produced
(d) According to the NRC, records of radioactive materials that are allowed to decay in storage must include the date of disposal, survey instrument used, background level of radiation, radiation level at the surface of the waste container, and name of the individual who performed the survey.
All of the following statements about the HVL are true EXCEPT:
(a)One HVL reduces the radiation intensity to half its original value.
(b) One HVL of lead will absorb the same amount of radiation of one HVL of aluminum.
(c) One HVL absorbs 50% of the photons emitted from a radiation source.
(d) Two HVLs reduce the radiation intensity to one quarter its original value.
(e) One HVL of lead is the same thickness as one HVL of aluminum.
(e) The thickness of a half-value layer (HVL) depends on the density of the shielding material and the photon energy of the radionuclide being shielded. The HVL for a radionuclide that emits a higher-energy photon must be thicker than the HVL for a lower-energy photon emitter to absorb 50% if the emitted photons. Thus, the HVL of lead for a low-energy photon emitter, such as 125I (27.5 keV), is 0.04 mm, but the HVL of lead for a higher-energy photon emitter, such as 137 Cs (662 keV), is 6.5 mm. Similarly, the HVL for lower-density materials. For example, for 131I, the HVL of a high-density material such as lead is 0.22 cm, but in the case of aluminum, a material with a much lower density than lead, the HVL is 2.6 cm. In this instance, more (a greater thickness) of lower-density material is required to absorb 50% of the emitted photons.
If a patient receives 20 mCi of [131I]sodium iodide instead of the prescribed dosage of 15 mCi for therapy of hyperthyroidism, which of the following individuals/agencies must be notified?
(a)NRC
(b) NRC and referring physician
(c) referring physician
(d) NRC and FDA
(e) FDA
(b) When a medical event (misadministration) occurs, the NRC requires the license to notify the NRC, the referring physician, and the involved individual, unless the referring physician determines, on the basis of medical judgment, that such notification would be harmful to the patient.
According to NRC regulations, the annual whole-body occupational dose limit (TEDE) for adults is:
(a)15 Rem
(b) 50 mRem
(c) 50 Rem
(d) 5000 mRem
(e) 10 Rem
(d) According to the NRC, the annual whole-body occupational dose limit for adults is 5,000 milliRem or 5 Rem.
A “sharps” container reads 50 mR/hr when it is placed in storage. It contains only 99mTc waste. According to NRC regulations, when can the container be disposed of as nonradioactive biohazardous waste?
(a)when the exposure rate drops to 1/10 of the original exposure rate
(b) when the container gives only a background reading with a survey meter
(c) when the exposure rate drops to 1/10 of the original exposure rate
(d) when the container gives only a background reading with a wipe test
(e) when the container gives a reading less than 5 mR/hr
(b)According to NRC regulations, decay in storage of radioactive materials requires that the materials remain in storage until the radioactivity is indistinguishable from background radiation using a survey meter on the most sensitive scale and without any shielding in place. Before disposal, all radiation labels must be obliterated unless the materials are in a container that will be managed as biomedical waste when released from the licensees.
According to the NRC, areas where therapeutic radiopharmaceuticals are prepared or administered must be surveyed:
(a)weekly
(b) monthly
(c) quarterly
(d) after each therapeutic dosage is prepared or administered
(e) at the end of each day a therapeutic dosage is prepared or administered
(e) NRC regulations require a survey of areas where radiopharmaceuticals that require a written directive are prepared for administered. This would include therapeutic radiopharmaceuticals and dosages of 131I greater than 30 uCi. the survey is to be performed at the end of the day. As of October 2002, the NRC no longer requires daily surveys and weekly wipe tests. Instead it allows facilities to establish a survey and wipe test schedule. the schedule must be reasonable, based on the need to determine radiation levels, concentrations or quantities of radioactive materials, and potential radiological hazards.
What is the measured exposure rate shown on the diagram of the G-M meter depicted here?
(needle at 0.6 mR/hr and knob at X10)
(a)0.06 mR/hr
(b) 6.0 mR/hr
(c) 0.6 mR/hr
(d) 60 mR/hr
(e) 0.006 mR/hr
(b) The measured exposure rate is the product of the number indicated by the needle on the meter and the scale. In this example, the reading on the meter is 0.6 on a scale of 10. Thus, 0.6 mR/hr x 10 = 6 mR/hr
According to the NRC, the NRC and the final delivery carrier must be notified if the exposure rate at the surface of a package containing radioactive materials exceeds:
(a)100 mR/hr
(b) 2,000 mR/hr
(c) 1,000 mR/hr
(d) 200 mR/hr
(e) 10 mR/hr
(d) According to the NRC, both the NRC and the final delivery carrier must be notified if the exposure rate of a radioactive package is in excess of 200 mR/hr at the package surface or in excess of 10 mR/hr at 3 ft from the package surface.
Contamination on the surface of the skin is best removed by:
(a)flushing the area with hot water
(b) cleansing the area with lukewarm water and detergent
(c) scrubbing the area with a stiff brush
(d) rubbing the area with an abrasive cleanser
(e) cleansing the area with hydrogen peroxide
(b) Decontamination of the skin should be attempted with a mild detergent and lukewarm water to avoid irritating the skin. Abrasive materials, scrubbing, and hot water all can increase absorption of the radioactivity through the skin.
According to NRC regulations, which of the following concerning restricted areas is TRUE?
(a)Patient rooms become restricted areas after the patient has received a radiopharmaceutical.
(b) Only areas where radiopharmaceuticals are stored must be designated as restricted areas.
(c) Radiation area monitors are required in restricted areas.
(d) Restricted areas must be locked when authorized personnel are not present.
(e) Everyone entering or leaving a restricted area must be surveyed.
(d) The NRC requires that access to restricted areas must be limited to prevent individuals from being exposed to radiation or radioactive materials that may cause undue risk. To control access, restricted areas must be locked when authorized staff are not present.
According to NRC regulations, radioactive waste can be decayed in storage if:
(a)the exposure rate at the time of storage is less than 5 mR/hr at the surface
(b) the exposure rate at the time of storage is less than 5 R/hr at the surface
(c) it has a physical half-life of less than 120 days
(d) it has a physical half-life of less than 1 year
(e) it has a physical half-life of less than 100 days
(c) According to the NRC, radioactive materials must be decayed in storage if the half-life is less than 120 days.
If the ambient exposure rate in a hot lab is determined to be 1.2 mR/hr, what will be the radiation dose to a technologist as a result of 3 hr of work in the lab?
(a)3.6 mRem
(b) 0.4 mRem
(c) 0.06 mRem
(d) 50 mRem
(e) 40 mRem
(a) To determine the total dose, multiply the exposure rate by the time of exposure. In this case:
1.2 mR/hr x 3h = 3.6 mR
However, the exposure to people is recorded in mRem, With gamma energies used in diagnostic nuclear medicine, R = Rem, so mR can be directly converted to mRem.
Which of the following must be performed before a package containing radioactive materials can be returned to a vendor?
(a)Confirm that the exposure rate does not exceed background levels.
(b) Perform a wipe test to assure there is no surface contamination.
(c) Cover each individual vial with a waterproof covering.
(d) Notify the NRC that a shipment is being made.
(e) Performing a calibration check on the dose calibrator.
(b) DOT regulations require that a survey of the package be performed to verify that there i no surface contamination before shipping packages containing radioactive materials.
Which of the following is a primary source of radiation exposure to the technologist who performs PET imaging?
(a)Bremsstrahlung radiation from the patient
(b) positrons escaping from the patient
(c) y rays from the long-lived source used for transmission scanning
(d) electromagnetic radiation from the PET camera
(e) Compton scatter from the patient
(e) The primary sources of radiation exposure to the technologist who performs PET imaging are from the radiopharmaceutical dosages before and during administration and from the Compton scatter escaping the patient’s body. Because they are particles, positrons will be absorbed by body tissue and will not be emitted from the body.
Which of the following personnel monitors would be appropriate for use when monitors are changed at 3 mo intervals?
(a)TLD or OSL
(b) TLD
(c) OSL
(d) film badge
(e) pocket dosimetry
(a) Either a TLD or an OSL can be used because the accuracy of the reading is not affected by time. The film in a film badge may begin to fog within this period of time. which may result in inaccurate exposure readings.
A linearity test was performed on a dose calibrator and these data were collected:
Day - Time - Calculated activity (mCi) - measured activity (mCi)
1 - 0700 - 20.0 - 20.0
- 1300 - 10.0 - 9.50
- 1900 - 5.0 - 4.75
2 - 0700 - 1.26 - 1.20
- 1300 - 0.63 - 0.60
- 1900 - 0.32 - 0.30
3 - 0700 - 0.08 - 0.076
- 1300 - 0.04 - 0.038
- 1900 - 0.02 - 0.019
Based on these results, which of the following statements is TRUE?
(a)The instrument consistently measures higher than expected.
(b) According to the standard of practice, the instrument is operating within limits.
(c) The instrument measures lower activities more accurately than higher activities.
(d) The instrument measures higher activities more accurately than lower activities.
(e) According to the standard of practice, the instrument is not operating within limits.
(b) The NRC requires that dose calibrators be tested for proper functioning according to nationally recognized standards. The standard of practice dictates that the measured activity should be within +-10% of the expected activity when the instrument is tested for linearity. All 9 measured activities are approximately 5% of the calculated values. Therefore, the results of this test are within acceptable linearity limits.
A dose calibrator accuracy test may be performed with which of the following radioactive sources?
(a)100 mCi 99mTc
(b) 75 uCi 137Cs
(c) 60 uCi 99mTc
(d) 25 uCi 137Cs
(e) 75 uCi 99mTc
(b) Various long-lived sources can be used to test accuracy. At least 50 uCi of 137Cs, 57Co, or 133Ba should be used. 99mTc is not an appropriate choice because it is relatively short-lived.
On the basis of the spectrometer calibration curve shown here:
(peak at 875)
the operating voltage of the instrument is:
(a)875
(b) 850
(c) 800
(d) 885
(e) 900
(a) Calibrating a scintillation spectrometer involves the determination of the operating voltage applied to the dynodes of the photomultiplier tube. A reference standard, such as 137Cs, is counted at various voltage settings, and the counts are recorded. Then, the net counts per minute versus the voltage are plotted on linear graph paper. From the graph, 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.
Extrinsic uniformity is performed daily on a scintillation camera with a 57Co sheet source and a low-energy all-purpose parallel-hole collimator. From the data shown here: Day - Time to collect 2 million counts June 1 - 240 sec June 2 - 241 sec June 3 - 245 sec June 4 - 242 sec June 5 - 560 sec all of the following may have caused the decreased sensitivity seen on June 5 EXCEPT: (a)incorrect photopeak/window setting
(b) incorrect collimator
(c) a cracked crystal
(d) incorrect acquisition matrix
(e) a malfunctioning PMT
(d) Sensitivity is expressed as counts per minute per microcurie. from the data presented, there is a sudden change in sensitivity from one day to the next. If the window is not set correctly over the photopeak, it will take longer to acquire the specified number of counts. Likewise, using a collimator that has less sensitivity than a low-energy, all-purpose collimator (such as a high-resolution or medium-energy collimator) will require additional time to collect the counts, With a cracked crystal, the photopeak is broadened, thus decreasing the system’s energy resolution and causing decreased counts in a given period of time. If an acquisition is set to terminate after a preset number of counts, the matrix size will not affect the length of the acquisition.
A technologist performs a uniformity test on a scintillation camera using a 99mTc point source and obtains the image shown here.
(uneven uniformity)
What should the technologist do next?
(a)Arrange for camera service.
(b) Record the results and proceed with imaging patients.
(c) Move the point source closer to the face of the detector.
(d) Move the point source farther from the face of the detector.
(e) Remove the collimator and repeat the acquisition.
(e) Camera uniformity may be performed intrinsically (without the collimator) or extrinsically (with the collimator in place). Intrinsic uniformity images may be acquired with a point source placed at 3-5 UFOV (useful fields of view) from the crystal or with a sheet source placed over the crystal. Extrinsic uniformity must be performed with a sheet source placed on the crystal. the image shown was performed with a collimated point source. Therefore, the distribution of radioactivity over the face of the crystal is not even. The technologist should either remove the collimator and repeat the image or use a radionuclide sheet source with the collimator in place to obtain the uniformity image.
According to standards of practice, how often must the accuracy of a dose calibrator be determined?
(a)quarterly
(b) annually
(c) monthly
(d) daily
(e) hourly
(b) According to the standard of practice, the accuracy of a dose calibrator should be tested at installation and annually thereafter.
The following center of rotation values were obtained on a SPECT camera:
Date - COR value
10/1 - 32.51
10/8 - 32.59
10/15 - 32.48
10/22 - 32.38
10/29 - 32.58
On October 29, the most appropriate action for the technologist is to:
(a)Transfer any SPECT studies to a different computer terminal for processing.
(b) Arrange for camera service.
(c) Acquire SPECT studies using the October 22 value.
(d) Acquire SPECT studies using the October 29 value.
(e) Acquire SPECT studies using the October 01 value.
(d) COR values should vary by no more than 1/2 pixel. Deviations greater than 1/2 pixel may degrade resolution in reconstructed images. The values presented are within the 1/2-pixel limit. Therefore, the technologist can use the camera for SPECT studies using the most recent value.
How often should linearity and spatial resolution tests be performed on a scintillation camera?
(a)daily
(b) weekly
(c) monthly
(d) quarterly
(e) yearly
(b) The standard of practice calls for performance of linearity and spatial resolution testing on a weekly basis.
If a 67Ga static image is acquired into a 128 x 128 byte mode matrix using the photopeaks at 93, 185, and 300 keV, how much computer memory is required to store the image?
(a)256 kB
(b) 64 kB
(c) 32 kB
(d) 128 kB
(e) 16 kB
(e) Counts from the three photopeaks are collected in one acquisition matrix to form a single 67Ga image. Therefore, one set of storage locations in computer memory is needed. One 128 x 128 byte-mode matrix contains 16,384 bytes. A kilobyte (kB) contains 1,024 bytes. To convert bytes to kilobytes:
16,384 bytes x 1 kB/1024 bytes = 16 kB
Which of the following techniques is used to help eliminate the “star” effect created during tomographic reconstruction?
(a)filtered backprojection
(b) center of rotation offset correction
(c) oversampling
(d) uniformity correction
(e) iterative reconstruction
(a) Tomographic images may be reconstructed from the planar projections using a technique called backprojection. This creates a star pattern as the ray sums are projected back along a line in the reconstruction matrix. the use of a ramp filter during the process helps eliminate much of the “star” artifact.
A technologist performs a linearity test on a dose calibrator. The expected activity at a given time is 28.2 uCi, and the actual reading is 27.0 uCi. Which of the following statements is correct?
(a)The instrument should be repaired or replaced.
(b) The instrument can be used to measure activities in the microcurie range.
(c) A correction factor of 0.96 should be applied when measuring activities in the microcurie range.
(d) A correction factor of 1.04 should be applied when measuring activities in the microcurie range.
(e) A correction factor of 1.14 should be applied when measuring activities in the microcurie range.
(b) if the percentage error in the measurement is less than 10%, then the instrument can be used as is. The measured activity falls within +-10% of the expected value, Therefore, no correction factor is needed.
Which of the following instruments is most appropriate for detecting low-level accidental contamination?
(a)thermoluminescent dosimeter
(b) cutie pie (ionization chamber)
(c) Geiger-Mueller counter
(d) pocket dosimeter
(e) optically stimulated luminescence dosimetry
(c) The Geiger-Mueller (G-M) counter is best suited for detecting low-level contamination because it is sensitive to exposure rates just above background, although the readings are not as accurate as those obtained with an ionization chamber. The G-M has a quicker response time compared with the ionization chamber. Although a pocket dosimeter can give an immediate reading, it cannot be used to localize contamination.
Image noise can be decreased during dedicated PET imaging by:
(a)decreasing the distance between the patient and the detectors
(b) using 2D mode
(c) decreasing the dosage activity
(d) scanning for a longer time
(e) using 4D mode
(d) The more data, the smaller the effect of the randomness of radioactive decay. Scanning for a longer time increases the number of counts acquired, thereby decreasing noise. Using 2D mode allows for more, because it accepts cross-ring interactions. Decreasing the dosage decreases counts and, therefore, increases noise. In a dedicated PET unit, the detectors are stationary on a non-adjustable ring. The distance between the patient and the detectors cannot be adjusted, except to center the imaging pallet in the middle of the ring.
What is the standard maximum acceptable % energy resolution measured with 137Cs for a NaI(Tl) scintillation detector?
(a)8%
(b) 12%
(c) 20%
(d) 22%
(e) 25%
(b) The percentage energy resolution should not exceed 12%. If the photopeak has broadened beyond this point, the instrument cannot accurately distinguish one energy from another.
A 10% window for 662 keV is set on a spectrometer with a lower-level discriminator (LLD) and an upper-level discriminator (ULD). If each increment on the discriminator dial equals 1 keV, what should be the settings for the LLD and the ULD?
(a)LLD = 586; ULD = 728
(b) LLD = 657; ULD = 667
(c) LLD = 652; ULD = 672
(d) LLD = 629; ULD = 695
(e) LLD = 667; ULD = 677
(d) Half the percentage of the window is above and half is below the designated energy. The window is expressed as a percentage of the energy of the radionuclide. In this case, it will be 662 keV, because 5% of 662 keV = 33 keV. The LLD will be set at the lower limit of the window (629 keV), and the ULD will be set at the upper limit (695 keV).
Which of the following radiation monitoring devices is best suited to survey a patient who has received 150 mCi of 131I for therapy?
(a)pocket ionization chamber
(b) portable ionization chamber
(c) Geiger-Mueller counter
(d) dose calibrator
(e) liquid scintillation counter
(b) A portable ionization chamber, sometimes referred to as a cutie pie, is used to measure areas of high photon intensity. This instrument gives a direct measurement of the total number of ion pairs produced per unit time and, therefore, is more accurate than a Geiger-Mueller counter when surveying a large amount of radioactivity.
