NucMed: Midterm

U-235

Mo-99 is Produced by the fission of _____

fission moly

The productof fission is called

Mo-99

chemically purified and passed to an ion exchange column for further processing.

alumina (Al₂O₃)

The generator contains a special material called _________, which helps separate Tc-99m

from Mo-99.

Elution Process

The generator is set to a slightly acidic environment to help the molybdate ions (from Mo-99)

bind to the alumina.

23 hours

The process of elution (releasing Tc-99m) usually takes about _______

50%

About _____ of the maximum Tc-99m is available in 4.5 hours.

once a day

The generator can be "milked" (eluted) more than ____________ meaning Tc-99m can be extracted

multiple times for use.

Wet systems

are typically used in regional radiopharmacies. They use normal saline (0.9%) to extract the Tc-99m from the generator.

Dry systems

used in imaging clinics. These systems use a vacuum vial to collect the Tc-99m after it's been eluted (released from the generator).

500 mL

The wet system uses a ______ reservoir of

0.9% saline to elute (wash out) the Tc-99m

from the Mo-99 in the generator.

0.9%

The wet system uses a 500 mL reservoir of

_____ saline to elute (wash out) the Tc-99m

from the Mo-99 in the generator.

2.8 days

Mo-99 has a half-life of

elution

The Mo-99 is replenished by

elution

extracting Tc-99m from the generator

1-2 weeks

The Tc-99m generator is typically used for about

Mo-99/Tc-99m generator

is used to produce Tc-99m, which is commonly used for nuclear medicine imaging.

Tc-99m

The only desired radionuclide in the Mo-99/Tc-99m generator eluate is

Tc-99m

used for diagnostic imaging in nuclear medicine

contamination (impurity)

Any other radionuclide present is considered

Mo-99 breakthrough

This occurs when Mo-99 breaks through the column during elution. This is called

Ruthenium-99

Tc-99 Decays into

2.1 × 10⁵ years

Tc-99 half life

Radionuclide purity

refers to the presence of only Tc-99m in the generator eluate.

Mo-99

The most common contaminant is ____, which increases radiation exposure without diagnostic benefit.

0.15 μCi per 1 mCi

The NRC limit for Mo-99 breakthrough is _____ of Tc-99m.

Increases patient radiation dose

Does not improve imaging

Reduces radiopharmaceutical purity

Excess Mo-99:

Chemical purity

refers to the absence of chemical contaminants in the generator eluate.

aluminum (Al³⁺)

The most common chemical contaminant is ______ from Al₂O₃ (alumina) column packing material.

regular quality control check

is performed on the generator eluate to detect aluminum contamination.

aluminum contamination

regular quality control check is performed on the generator eluate to detect

Al₂O₃ (alumina)

The most common chemical contaminant is aluminum (Al³⁺) from _______

Colorimetric qualitative spot testing

is used to check if unacceptable aluminum levels are present in the elute.

Colorimetric qualitative spot testing

The test involves:

Adding reagent to sample

Observing color change

Color intensity indicates amount of aluminum present

≤ 10 μg aluminum per mL of eluate

Maximum acceptable aluminum level:

Eluate must not be used

Can cause poor radiopharmaceutical distribution

If aluminum exceeds this level:

biodistribution

High aluminum levels can interfere with radiopharmaceutical _____________

Tc-99m sulfur colloid

excess aluminum can cause increased lung activity when using _______

Tc-99m methylene diphosphonate (MDP)

excess aluminum can cause abnormal liver uptake when using

+7

When Tc-99m is eluted from the generator, it is expected to be in the __oxidation state

pertechnetate

Radiochemical purity

refers to the percentage of Tc-99m in the +7 oxidation state

pertechnetate (TcO₄⁻)

When Tc-99m is eluted from the generator, it is expected to be in the +7 oxidation state. This form is called

Tc-99m pertechnetate (+7)

the desired radiochemical form

≥95%

The USP requires _____ of Tc-99m in this form

oxidation state

Proper labeling depends on this correct __________

+4, +5, +6

Impurity states →

Thin-Layer Chromatography (TLC)

Reduced states (+4, +5, +6) are impurities and are detected using _________________

Thin-Layer Chromatography (TLC)

This method:

Separates different chemical forms

Measures percentage of desired Tc-99m

Accurate Localization

Impurities from improper Tc-99m oxidation states can cause misplacement in the body, leading

to incorrect imaging.

Reduced Imaging Quality

Impurities interfere with radiopharmaceutical distribution, causing blurry images and difficulty

detecting conditions like tumors.

Increased Radiation Exposure

Impurities can result in extra radiation to healthy tissues, increasing the patient's exposure

without providing diagnostic value

Poor Labeling Efficiency

Low purity reduces the binding efficiency of the radiopharmaceutical, leading to incomplete or

unreliable diagnoses.

Inaccurate Quantification

Impurities disrupt the quantification of radiopharmaceuticals, resulting in incorrect diagnostic

results for procedures like blood flow or organ function assessments.

Chemical Purity

Fraction of wanted vs. unwanted

chemical in preparation

Radiochemical Purity

Fraction of total radioactivity in desired

chemical form

Radionuclide Purity

Fraction of total radioactivity in the form

of desired radionuclide

Physical Purity

Fraction of total pharmaceutical in

desired physical form

Biological Purity

Absence of microorganisms and

pyrogens

Chemical Purity

Amount of alumina breakthrough in Mo-99/Tc-

99m generator eluate

Radiochemical Purity

Amount of bound vs. unbound Tc-99m in Tc-

99m diphosphonate

Radionuclide purity

Ratio of Tc-99m vs. Mo-99 in generator eluate;

I-124 in an I-123 preparation

Physical Purity

Correct particle size distribution in Tc-99m

MAA preparation

Biological Purity

Sterile, pyrogen-free preparations

Add Tc-99m pertechnetate to the kit vial

Allow radiopharmaceutical formation

Withdraw patient dose

Measure activity in dose calibrator

Dispense/administer safely

Preparation of Tc-99m-labeled

radiopharmaceutical

Tc-99m sodium pertechnetate

Meckel's diverticulum detection, salivary and thyroid gland

scintigraphy

Tc-99m sulfur colloid

Lymphoscintigraphy

Tc-99m diphosphonate

Liver/spleen scintigraphy, bone marrow scintigraphy

Tc-99m macroaggregated albumin (MAA)

Pulmonary perfusion scintigraphy, liver intrarterial

perfusion scintigraphy

Tc-99m red blood cells

Radionuclide ventriculography, gastrointestinal bleeding,

hepatic hemangioma

Tc-99m diethylenetriamine-pentaacetic

acid (DTPA)

Renal dynamic scintigraphy, lung ventilation (aerosol),

glomerular filtration rate

Tc-99m mercaptoacetyltriglycine (MAG₃)

Renal dynamic scintigraphy

Tc-99m dimercaptosuccinic acid (DMSA)

Renal cortical scintigraphy

Tc-99m imidodisuccinic acid (HIDA)

Hepatobiliary scintigraphy

Tc-99m sestamibi (Cardiolite)

Myocardial perfusion scintigraphy, breast imaging

Tc-99m teboroxime (Myoview)

Myocardial perfusion scintigraphy

Tc-99m exametazime (HMPAO)

Cerebral perfusion scintigraphy, white blood cell labeling

Tc-99m bicisate (ECD)

Cerebral perfusion scintigraphy