Pharmaceutical applications of radioisotopes MCQs With Answer

Introduction: The pharmaceutical applications of radioisotopes MCQs with answer provide B.Pharm students a focused review of radiopharmaceutical science, diagnostic imaging, and therapeutic radionuclide use. This concise, keyword-rich guide covers radiopharmaceutical production, radioisotope labeling, radiochemistry, dosimetry, quality control, sterility, radiopharmacology, and radiation safety principles such as ALARA. Emphasis on common isotopes (Tc-99m, I-131, F-18, P-32, Y-90), generator systems, and regulatory/GMP considerations helps students prepare for exams and clinical practice. Practical MCQs reinforce concepts like biodistribution, specific activity, radiochemical purity, and waste management for safe and effective use. Now let’s test your knowledge with 50 MCQs on this topic.

Q1. What is the most commonly used radioisotope in diagnostic nuclear medicine due to its ideal half-life and gamma energy?

• Fluorine-18 (F-18)
• Iodine-131 (I-131)
• Technetium-99m (Tc-99m)
• Phosphorus-32 (P-32)

Correct Answer: Technetium-99m (Tc-99m)

Q2. Which decay mode is primarily responsible for gamma photon emission used in imaging?

• Alpha decay
• Beta-minus decay
• Electron capture followed by gamma emission
• Spontaneous fission

Correct Answer: Electron capture followed by gamma emission

Q3. Which unit measures radioactivity in the SI system?

• Curie (Ci)
• Gray (Gy)
• Sievert (Sv)
• Becquerel (Bq)

Correct Answer: Becquerel (Bq)

Q4. In radiopharmaceutical production, what does “specific activity” refer to?

• Activity per unit mass of labeled compound
• Total activity in the vial
• Total mass of carrier present
• Radiochemical purity percentage

Correct Answer: Activity per unit mass of labeled compound

Q5. Which radioisotope is commonly used in PET imaging?

• Technetium-99m (Tc-99m)
• Fluorine-18 (F-18)
• Iodine-131 (I-131)
• Carbon-14 (C-14)

Correct Answer: Fluorine-18 (F-18)

Q6. What is the primary purpose of a Mo-99/Tc-99m generator?

• To produce F-18 for PET scans
• To extract Tc-99m by elution from parent Mo-99
• To sterilize radiopharmaceutical kits
• To measure radiation dose in patients

Correct Answer: To extract Tc-99m by elution from parent Mo-99

Q7. Radiochemical purity testing assesses what parameter in a radiopharmaceutical?

• Sterility of the preparation
• Proportion of radioactivity in the desired chemical form
• Patient absorbed dose
• pH of the solution

Correct Answer: Proportion of radioactivity in the desired chemical form

Q8. Which material is most appropriate for shielding gamma emitters like Tc-99m?

• Lead
• Aluminum
• Glass
• Polyethylene

Correct Answer: Lead

Q9. What is ALARA in radiation safety?

• As Long As Radiation Allows
• As Low As Reasonably Achievable
• Average Level of Atomic Radiation Allowed
• Atomic Leakage and Radiation Assessment

Correct Answer: As Low As Reasonably Achievable

Q10. Which test ensures that a radiopharmaceutical is free from bacterial contaminants?

• Radiochemical purity
• Sterility test
• Gamma camera calibration
• Specific activity measurement

Correct Answer: Sterility test

Q11. Which radionuclide is commonly used for thyroid therapy?

• Technetium-99m (Tc-99m)
• Iodine-131 (I-131)
• Fluorine-18 (F-18)
• Strontium-89 (Sr-89)

Correct Answer: Iodine-131 (I-131)

Q12. What does radionuclidic purity describe?

• Percentage of radioactive impurities in relation to total activity
• Chemical impurities present
• pH compatibility with blood
• Sterility assurance level

Correct Answer: Percentage of radioactive impurities in relation to total activity

Q13. Which parameter is NOT directly assessed by a dose calibrator?

• Activity of a radioisotope
• Calibration factor for isotopes
• Gamma energy spectrum
• Decay-corrected activity

Correct Answer: Gamma energy spectrum

Q14. What is the biological half-life?

• Time for half the atoms to undergo radioactive decay
• Time for half the activity to be removed biologically from the body
• Combined physical and chemical decay time
• Time to reach maximum tissue uptake

Correct Answer: Time for half the activity to be removed biologically from the body

Q15. Which chelating agent is commonly used to label peptides with radiometals?

• EDTA
• DTPA or DOTA
• Sodium chloride
• Glucose

Correct Answer: DTPA or DOTA

Q16. What is “carrier-free” radioisotope?

• Isotope mixed with stable carrier atoms
• Isotope produced without any chemical carrier of the same element
• Isotope with long half-life
• Isotope that emits only beta particles

Correct Answer: Isotope produced without any chemical carrier of the same element

Q17. Which imaging modality uses gamma-emitting radiopharmaceuticals and a rotating gamma camera?

• PET
• SPECT
• MRI
• CT

Correct Answer: SPECT

Q18. For PET imaging with F-18 FDG, what physiological process is primarily imaged?

• Bone turnover
• Glucose metabolism
• Thyroid uptake
• Renal filtration rate

Correct Answer: Glucose metabolism

Q19. What is the primary radiochemical challenge when labeling small molecules with radiohalogens like I-131?

• Formation of metal-chelate complexes
• Oxidative substitution and deiodination in vivo
• Rapid beta emission interfering with imaging
• Excessive specific activity preventing labeling

Correct Answer: Oxidative substitution and deiodination in vivo

Q20. Which waste category requires decay-in-storage until activity falls to background?

• Biological hazardous waste
• Short-lived radioactive waste
• High-level nuclear waste
• Chemical solvent waste

Correct Answer: Short-lived radioactive waste

Q21. What is the role of a radiopharmacy in a hospital?

• Manufacture all chemotherapy drugs
• Prepare, test, and dispense radiopharmaceuticals under GMP
• Perform all surgical procedures involving radiation
• Regulate external radiation therapy machines

Correct Answer: Prepare, test, and dispense radiopharmaceuticals under GMP

Q22. Which isotope is primarily used for bone pain palliation?

• Yttrium-90 (Y-90)
• Strontium-89 (Sr-89)
• Technetium-99m (Tc-99m)
• Fluorine-18 (F-18)

Correct Answer: Strontium-89 (Sr-89)

Q23. Which quality control method assesses radionuclidic identity?

• Thin-layer chromatography for radiochemical purity
• Gamma spectroscopy or energy peak analysis
• Sterility culture
• pH measurement

Correct Answer: Gamma spectroscopy or energy peak analysis

Q24. What regulatory documentation is essential for radiopharmaceutical lot release?

• Patient consent form
• Certificate of analysis including sterility, radiochemical and radionuclidic purity
• Last year’s training attendance sheet
• Imaging equipment service log

Correct Answer: Certificate of analysis including sterility, radiochemical and radionuclidic purity

Q25. In radiolabeling proteins, which functional group on the protein is commonly targeted for covalent attachment?

• Hydroxyl groups only
• Amino groups (lysine residues) or thiol groups (cysteine)
• Carboxyl groups only
• Phosphate groups

Correct Answer: Amino groups (lysine residues) or thiol groups (cysteine)

Q26. Which isotope is commonly used for radioimmunotherapy?

• Technetium-99m (Tc-99m)
• Iodine-131 (I-131)
• Fluorine-18 (F-18)
• Carbon-14 (C-14)

Correct Answer: Iodine-131 (I-131)

Q27. What is “kit formulation” in radiopharmacy?

• A pre-prepared sterile vial containing precursors which are labeled with a radioisotope at point-of-use
• Method for calibrating dose calibrators
• Packaging used for radioactive waste
• Technique for PET image reconstruction

Correct Answer: A pre-prepared sterile vial containing precursors which are labeled with a radioisotope at point-of-use

Q28. Which factor most affects patient radiation dose from a radiopharmaceutical?

• Color of the vial
• Physical half-life, biological clearance, and administered activity
• Room temperature at administration
• Manufacturer of the radionuclide

Correct Answer: Physical half-life, biological clearance, and administered activity

Q29. What is the main advantage of a cyclotron-produced PET isotope like F-18?

• Extremely long half-life allowing indefinite storage
• High positron yield and suitable half-life for imaging biochemical processes
• Generates primarily gamma rays for SPECT
• Is inert and non-reactive for labeling

Correct Answer: High positron yield and suitable half-life for imaging biochemical processes

Q30. Which instrument is used to measure gamma energy peaks to confirm radionuclidic identity?

• pH meter
• Gamma spectrometer with scintillation detector or HPGe detector
• Mass spectrometer
• UV-Vis spectrophotometer

Correct Answer: Gamma spectrometer with scintillation detector or HPGe detector

Q31. What is the principle of radiolabeling for ADME studies in drug development?

• Use of non-radioactive tracers only
• Attach a radioisotope to the drug to trace absorption, distribution, metabolism and excretion
• Use radioisotopes to increase drug potency
• Replace drug with a radiopharmaceutical for therapy

Correct Answer: Attach a radioisotope to the drug to trace absorption, distribution, metabolism and excretion

Q32. Which isotope is a pure beta emitter used for intravascular brachytherapy?

• Yttrium-90 (Y-90)
• Technetium-99m (Tc-99m)
• Fluorine-18 (F-18)
• Iodine-123 (I-123)

Correct Answer: Yttrium-90 (Y-90)

Q33. How is radiochemical purity commonly assessed for Tc-99m labeled kits?

• Gamma camera imaging only
• Thin-layer chromatography or instant thin-layer chromatography (ITLC)
• Sterility testing
• Mass spectrometry

Correct Answer: Thin-layer chromatography or instant thin-layer chromatography (ITLC)

Q34. What is the main safety precaution when handling liquid radiopharmaceuticals?

• Never store at room temperature
• Use time, distance, and shielding principles, plus appropriate PPE to avoid contamination
• Always heat samples before use
• Avoid any radiation monitoring

Correct Answer: Use time, distance, and shielding principles, plus appropriate PPE to avoid contamination

Q35. Which isotope is often used for lung perfusion imaging?

• Technetium-99m labeled macroaggregated albumin (Tc-99m MAA)
• Iodine-131 sodium iodide
• Fluorine-18 FDG
• Strontium-89 chloride

Correct Answer: Technetium-99m labeled macroaggregated albumin (Tc-99m MAA)

Q36. What does “decay correction” account for when calculating activity?

• Change in activity due to physical decay over time
• Loss of sterility over time
• Change in chemical purity over time
• Loss of mass during handling

Correct Answer: Change in activity due to physical decay over time

Q37. In radiopharmaceutical kit preparation, which condition is critical to ensure product sterility?

• Working in a non-sterile bench is acceptable
• Use of aseptic technique and sterile vials during kit compounding and labeling
• No need for sterilization if radioactivity is high
• Only chemical purity matters, not sterility

Correct Answer: Use of aseptic technique and sterile vials during kit compounding and labeling

Q38. Which parameter helps predict organ radiation dose from a radiopharmaceutical?

• Specific activity alone
• Biodistribution and residence time in the organ
• Brand of generator
• Room humidity

Correct Answer: Biodistribution and residence time in the organ

Q39. What is “mass effect” in radiolabeling context?

• Effect of large sample containers on detector efficiency
• Excess non-radioactive carrier causing altered biodistribution or reduced specific activity
• Gravitational influence on radioactive decay
• Increased mass from shielding

Correct Answer: Excess non-radioactive carrier causing altered biodistribution or reduced specific activity

Q40. Which regulatory guideline is essential for radiopharmaceutical manufacturing quality?

• Good Laboratory Practice (GLP) only
• Good Manufacturing Practice (GMP) for radiopharmaceuticals
• Only ISO 9001 applies
• No regulations apply to radiopharmaceuticals

Correct Answer: Good Manufacturing Practice (GMP) for radiopharmaceuticals

Q41. Which isotope is suitable for sentinel lymph node imaging?

• Technetium-99m sulfur colloid
• Iodine-131 labeled proteins
• Fluorine-18 labeled glucose
• Carbon-14 labeled lipids

Correct Answer: Technetium-99m sulfur colloid

Q42. What is the recommended action if a radiopharmaceutical vial is found contaminated on the outside?

• Use it after wiping once with water
• Isolate, control access, perform contamination survey, decontaminate or discard per protocol
• Immediately inject into patient to avoid waste
• Seal it and place in regular trash

Correct Answer: Isolate, control access, perform contamination survey, decontaminate or discard per protocol

Q43. Which isotope is used for radioiodine uptake tests?

• Technetium-99m (Tc-99m)
• Iodine-123 (I-123) or Iodine-131 (I-131)
• Fluorine-18 (F-18)
• Phosphorus-32 (P-32)

Correct Answer: Iodine-123 (I-123) or Iodine-131 (I-131)

Q44. What is “theranostics” in nuclear pharmacy?

• Use of only diagnostic imaging agents
• Combination of diagnostic imaging and targeted radionuclide therapy using similar molecules labeled with different isotopes
• Non-radioactive therapeutic approaches
• Administration of multiple radiopharmaceuticals simultaneously for imaging

Correct Answer: Combination of diagnostic imaging and targeted radionuclide therapy using similar molecules labeled with different isotopes

Q45. What does high specific activity benefit in receptor-targeting radiopharmaceuticals?

• Increases non-specific binding
• Improves receptor occupancy with minimal mass, reducing pharmacologic effects
• Decreases radionuclidic purity
• Makes sterilization easier

Correct Answer: Improves receptor occupancy with minimal mass, reducing pharmacologic effects

Q46. Which isotope emits positrons leading to annihilation photons detected in PET?

• Technetium-99m (Tc-99m)
• Fluorine-18 (F-18)
• Iodine-131 (I-131)
• Phosphorus-32 (P-32)

Correct Answer: Fluorine-18 (F-18)

Q47. How is radiopharmaceutical stability commonly assessed after labeling?

• By measuring color only
• By repeated radiochemical purity assays over time under storage conditions
• By patient feedback immediately
• By counting pills in the vial

Correct Answer: By repeated radiochemical purity assays over time under storage conditions

Q48. Which physical property of an isotope is most critical when choosing it for therapeutic beta-emitting applications?

• Gamma photon abundance only
• Beta particle energy and path length in tissue
• Color of the isotope
• pH of the isotope solution

Correct Answer: Beta particle energy and path length in tissue

Q49. What is the common method to label monoclonal antibodies with radioisotopes?

• Direct thermal heating of antibody
• Use of bifunctional chelators or radioiodination methods for covalent attachment
• Mixing antibody with saline only
• Dilution with ethanol

Correct Answer: Use of bifunctional chelators or radioiodination methods for covalent attachment

Q50. Which practice minimizes occupational exposure during radiopharmaceutical dispensing?

• Maximizing handling time to ensure accuracy
• Using shielding, minimizing time, maximizing distance, and using remote handling tools
• Holding vials close to body to stabilize
• Not using any personal dosimetry

Correct Answer: Using shielding, minimizing time, maximizing distance, and using remote handling tools