Saudi Nuclear Medicine Club " Quiz #5 " @saudi_nmc

1. Tools for measuring personal exposure to radiation include all of the following except:

Thermoluminescent dosimeter

Pocket ionization chamber

Film badge

Geiger-Mueller Counter

Personnel exposure is measured by all of the choices except the Geiger-Mueller counter which is a gas fi lled ionization chamber. Because of dead time, it is typically used to measure small amounts of radiation.

Explanation

Personnel exposure is measured by all of the choices except the Geiger-Mueller counter which is a gas fi lled ionization chamber. Because of dead time, it is typically used to measure small amounts of radiation.

2. If an assay of a vial containing 131I shows 50 mCi present on May 2, approximately what will the assay show on May 18?

25 mCi

12.5 mCi

40 mCi

6 mCi

The half-life of 131I is 8.06 days. Since the time elapsed is about 2 half-lives, the original activity would be halved twice. (50 mCi/2 = 25 mCi, 25 mCi/2 = 12.5 mCi)

Explanation

The half-life of 131I is 8.06 days. Since the time elapsed is about 2 half-lives, the original activity would be halved twice. (50 mCi/2 = 25 mCi, 25 mCi/2 = 12.5 mCi)

3. The salivary glands may be imaged using:

3 mCi of 201Tl

5 mCi of 99mTc sestamibi

5 mCi of 99mTc pertechnetate

200 uCi of 123I sodium iodide

Pertechnetate is used for imaging the salivary glands, often to evaluate function or rule out masses.

Explanation

Pertechnetate is used for imaging the salivary glands, often to evaluate function or rule out masses.

4. what is the annual dose limit for occupational exposure?

20 mSv

2 mSv

20 mrem

2 mrem

The annual dose limit for occupational exposure is 20 mSv. This means that individuals who are exposed to radiation in their workplace should not receive more than 20 millisieverts of radiation in a year. This limit is set to protect workers from the harmful effects of radiation and to ensure their safety and well-being.

Explanation

The annual dose limit for occupational exposure is 20 mSv. This means that individuals who are exposed to radiation in their workplace should not receive more than 20 millisieverts of radiation in a year. This limit is set to protect workers from the harmful effects of radiation and to ensure their safety and well-being.

5. Which of the following will not affect thyroid uptake?

Iodinated contrast media

Propylthiouracil

Thyroid hormones

Beta blockers

Beta blockers will not affect thyroid uptake because they do not directly interfere with the thyroid's ability to take up iodine. Beta blockers primarily work by blocking the effects of adrenaline and reducing the heart rate, but they do not have a direct impact on thyroid function. On the other hand, iodinated contrast media, propylthiouracil, and thyroid hormones can all affect thyroid uptake in different ways.

Explanation

Beta blockers will not affect thyroid uptake because they do not directly interfere with the thyroid's ability to take up iodine. Beta blockers primarily work by blocking the effects of adrenaline and reducing the heart rate, but they do not have a direct impact on thyroid function. On the other hand, iodinated contrast media, propylthiouracil, and thyroid hormones can all affect thyroid uptake in different ways.

6. If no gallbladder is seen at one hour following injection of 99mTc DISIDA, what should be done?

Cimetidine should be given

Images should be taken at 24 hours

Images should be taken at 4 hours

The exam should be ended

Patients should fast 2–4 hours before hepatobiliary imaging. The gallbladder may not be visualized in patients who have recently eaten and in patients who have fasted for extended periods. The use of morphine can hasten visualization of the gallbladder by increasing bile fl ow to the gallbladder relative to the intestine. For patients in an extended fast, sincalide may be used (see explanation to question 5). If there is no gallbladder seen one hour following injection of radiopharmaceutical, delayed images should be obtained.

Explanation

Patients should fast 2–4 hours before hepatobiliary imaging. The gallbladder may not be visualized in patients who have recently eaten and in patients who have fasted for extended periods. The use of morphine can hasten visualization of the gallbladder by increasing bile fl ow to the gallbladder relative to the intestine. For patients in an extended fast, sincalide may be used (see explanation to question 5). If there is no gallbladder seen one hour following injection of radiopharmaceutical, delayed images should be obtained.

7. Which of the following isotopes would be effectively shielded by a plastic syringe?

67Ga

89Sr

99mTc

81mKr

133Xe

Beta emitters can be effectively shielded by a few millimeters of plastic or lucite. If shielded with lead, bremsstrahlung radiation will be produced from the slowing beta particles

Explanation

Beta emitters can be effectively shielded by a few millimeters of plastic or lucite. If shielded with lead, bremsstrahlung radiation will be produced from the slowing beta particles

8. If 15 minutes after injection of 8 mCi of 99mTc disofenin, the liver is not visualized, but the heart and kidneys are, what is the most likely reason?

Too little DISIDA was injected

The liver is not functioning properly

The gallbladder is obstructed

The patient is taking morphine

The patient has a very low bilirubin level

Iminodiacetic acids (IDAs) are cleared from the blood by the hepatocytes before they are secreted into the canaliculi. If the liver is not seen but there is cardiac and renal activity at 15 minutes after injection, this likely indicates that there is a problem of liver function.

Explanation

Iminodiacetic acids (IDAs) are cleared from the blood by the hepatocytes before they are secreted into the canaliculi. If the liver is not seen but there is cardiac and renal activity at 15 minutes after injection, this likely indicates that there is a problem of liver function.

9. A patient is only able to tolerate 3 images during a 201Tl chloride myocardial perfusion study. From those views listed, which would be the best choice of images to obtain?

RAO 10°, LAO 45°, and left lateral

Anterior, LAO 25° and LAO 60°

Anterior, LAO 45° and LAO 70°

Anterior, LAO 70° and left lateral

In general, the 45° LAO should allow visualization of the septum and the inferoapical and posterolateral sections of the left ventricular wall. The anterior would then show the inferior, apical and the anterolateral wall sections and the 70° LAO would allow evaluation of the anterior, apical, inferior and posterolateral all sections. If there is not the septum is not well resolved on the 45° LAO due to the patient’s anatomy, another angle could be chosen, and the remaining two angles calculated by subtracting 45° for the “anterior” and by adding 25° for the steep lateral oblique.

Explanation

In general, the 45° LAO should allow visualization of the septum and the inferoapical and posterolateral sections of the left ventricular wall. The anterior would then show the inferior, apical and the anterolateral wall sections and the 70° LAO would allow evaluation of the anterior, apical, inferior and posterolateral all sections. If there is not the septum is not well resolved on the 45° LAO due to the patient’s anatomy, another angle could be chosen, and the remaining two angles calculated by subtracting 45° for the “anterior” and by adding 25° for the steep lateral oblique.

10. On a normal renal scan, gallbladder activity is noted. This indicates that the scan was performed using:

99mTc DMSA

99mTc DTPA

99mTc GH

99mTc MAG3

A small percentage of 99mTc MAG3 may be taken up in the liver and gall bladder in normal patients, and this may be more pronounced in patients with poor renal function.

Explanation

A small percentage of 99mTc MAG3 may be taken up in the liver and gall bladder in normal patients, and this may be more pronounced in patients with poor renal function.