Properties of α, β, γ radiations MCQs With Answer

Properties of α, β, γ radiations MCQs With Answer
Understanding the properties of alpha (α), beta (β) and gamma (γ) radiations is essential for B.Pharm students studying radiopharmaceuticals, radiation safety, dosimetry and therapeutics. This introduction covers key concepts like charge, mass, penetration power, ionization potential, linear energy transfer (LET), biological effects, shielding materials and detection methods. Mastery of these topics helps in safe handling of radioactive materials, interpreting decay schemes and applying radiation in diagnosis and treatment. Clear knowledge of half-life, range in tissue, and relative biological effectiveness (RBE) is crucial for pharmacy practice involving radiotracers. Now let’s test your knowledge with 50 MCQs on this topic.

Q1. Which property correctly distinguishes alpha particles from beta particles?

• Alpha particles carry a +2 charge and have high mass.
• Alpha particles carry a -1 charge and have low mass.
• Alpha particles are neutral and have no mass.
• Alpha particles are high-energy photons with no charge.

Correct Answer: Alpha particles carry a +2 charge and have high mass.

Q2. Which statement about gamma radiation is accurate?

• Gamma radiation consists of high-energy electrons emitted from the nucleus.
• Gamma radiation is a stream of neutrons with no charge.
• Gamma radiation is high-energy electromagnetic radiation with no mass or charge.
• Gamma radiation is identical to alpha radiation in penetration.

Correct Answer: Gamma radiation is high-energy electromagnetic radiation with no mass or charge.

Q3. Which material is most effective for shielding gamma rays in a clinical setting?

• Paper sheets.
• Lead or heavy dense metals.
• Aluminum foil.
• Thin plastic film.

Correct Answer: Lead or heavy dense metals.

Q4. Which radiation has the greatest linear energy transfer (LET)?

• Gamma rays.
• Beta particles.
• Alpha particles.
• X-rays.

Correct Answer: Alpha particles.

Q5. Beta minus (β-) decay involves which change in the nucleus?

• A proton converts to a neutron with positron emission.
• A neutron converts to a proton with emission of an electron and antineutrino.
• A neutron converts to a proton with emission of a positron.
• A proton and neutron annihilate producing gamma rays.

Correct Answer: A neutron converts to a proton with emission of an electron and antineutrino.

Q6. What is the primary biological risk from alpha-emitting radionuclides if inhaled or ingested?

• Minimal risk because alpha cannot ionize matter.
• Severe local tissue damage due to high LET and ionization.
• Whole-body gamma exposure equivalent to external gamma sources.
• No risk because alpha particles are neutral.

Correct Answer: Severe local tissue damage due to high LET and ionization.

Q7. Which detector is most suitable for measuring gamma radiation in a hospital?

• Geiger-Müller tube with appropriate probe.
• Mercury thermometer.
• pH meter.
• Optical microscope.

Correct Answer: Geiger-Müller tube with appropriate probe.

Q8. Which property best describes the penetration range of beta particles in tissue?

• They penetrate several meters of lead.
• They travel only micrometers and are stopped by paper.
• They have moderate penetration, typically millimeters to centimeters in tissue.
• They are identical to gamma rays in penetration depth.

Correct Answer: They have moderate penetration, typically millimeters to centimeters in tissue.

Q9. Relative biological effectiveness (RBE) compares what?

• The physical energy of two photons only.
• The biological damage caused by different types of radiation for the same absorbed dose.
• The half-lives of two radionuclides.
• The shielding thickness required for alpha versus beta particles.

Correct Answer: The biological damage caused by different types of radiation for the same absorbed dose.

Q10. Which interaction is dominant for gamma rays in the diagnostic energy range (tens to hundreds of keV)?

• Alpha decay.
• Compton scattering and photoelectric effect depending on energy and Z.
• Beta emission.
• Strong nuclear force interactions.

Correct Answer: Compton scattering and photoelectric effect depending on energy and Z.

Q11. What is the typical mass number and charge change in alpha decay?

• Mass number decreases by 4 and charge decreases by 2.
• Mass number increases by 4 and charge increases by 2.
• Mass and charge remain unchanged.
• Mass number decreases by 1 and charge increases by 1.

Correct Answer: Mass number decreases by 4 and charge decreases by 2.

Q12. Which of the following best describes Bremsstrahlung radiation relevant to beta particles?

• Gamma ray emission from nuclear transitions only.
• X-ray produced when high-speed electrons decelerate in high-Z material.
• Alpha particle formation in heavy elements.
• Neutron emission during beta decay.

Correct Answer: X-ray produced when high-speed electrons decelerate in high-Z material.

Q13. Which unit measures absorbed dose of radiation in tissue?

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

Correct Answer: Gray (Gy).

Q14. Which unit accounts for biological effect of radiation, combining absorbed dose and radiation weighting?

• Becquerel (Bq).
• Sievert (Sv).
• Gray (Gy).
• Roentgen (R).

Correct Answer: Sievert (Sv).

Q15. Which process describes internal conversion accompanying gamma decay?

• Direct emission of an alpha particle instead of gamma.
• Excited nucleus transfers energy to an orbital electron, which is ejected.
• Spontaneous fission into two fragments.
• Beta particle capturing a neutrino.

Correct Answer: Excited nucleus transfers energy to an orbital electron, which is ejected.

Q16. For radiopharmaceutical labeling, which radiation property is most important for therapeutic alpha-emitters?

• Long-range penetration to reach distant organs.
• High LET and short range for targeted cell killing.
• No ionization to avoid tissue damage.
• Production of visible light for imaging.

Correct Answer: High LET and short range for targeted cell killing.

Q17. Which is true about beta plus (β+) decay (positron emission)?

• A neutron converts to a proton and emits an electron.
• A proton converts to a neutron and emits a positron and neutrino.
• A nucleus emits a gamma and becomes stable without charge change.
• An alpha particle captures an electron to become beta particle.

Correct Answer: A proton converts to a neutron and emits a positron and neutrino.

Q18. In PET imaging which radiation is detected externally?

• Single beta particles emitted from the nucleus.
• Back-to-back 511 keV annihilation gamma photons from positron annihilation.
• Alpha particles from tracer decay.
• Ultrasound waves generated by radiotracer decay.

Correct Answer: Back-to-back 511 keV annihilation gamma photons from positron annihilation.

Q19. Which interaction dominates energy loss of alpha particles in matter?

• Nuclear scattering exclusively.
• Ionization and excitation of atoms (electromagnetic interactions).
• Neutron capture processes.
• Gravitational interactions with nuclei.

Correct Answer: Ionization and excitation of atoms (electromagnetic interactions).

Q20. Half-life describes what characteristic of a radionuclide?

• Time taken for all atoms to decay.
• Time taken for half the initial number of radioactive nuclei to decay.
• Time to reduce radiation to zero with shielding.
• Time required for biological elimination only.

Correct Answer: Time taken for half the initial number of radioactive nuclei to decay.

Q21. Which factor increases the probability of photoelectric absorption for gamma rays?

• Higher photon energy and low-Z material.
• Lower photon energy and high-Z material.
• High photon energy and vacuum.
• Absence of electrons in absorber.

Correct Answer: Lower photon energy and high-Z material.

Q22. What is characteristic of beta emitters used in therapy (e.g., 90Y)?

• They emit high-energy electrons suitable for penetrating tumors a few millimeters to centimeters.
• They have zero biological impact and are used only for imaging.
• They behave identically to alpha emitters in tissue range.
• They emit only photons without charged particles.

Correct Answer: They emit high-energy electrons suitable for penetrating tumors a few millimeters to centimeters.

Q23. Which statement about Bremsstrahlung production is important for shielding beta emitters?

• Using high-Z shielding increases Bremsstrahlung yield and may increase exposure.
• High-Z shields eliminate Bremsstrahlung completely.
• Bremsstrahlung is irrelevant for medical beta emitters.
• Only alpha emitters produce Bremsstrahlung.

Correct Answer: Using high-Z shielding increases Bremsstrahlung yield and may increase exposure.

Q24. Linear Energy Transfer (LET) is best defined as:

• Energy lost per unit length by radiation as it traverses matter.
• Total energy emitted by a radionuclide per decay.
• Number of neutrons emitted per decay.
• Half-life expressed in energy units.

Correct Answer: Energy lost per unit length by radiation as it traverses matter.

Q25. For external contamination monitoring of surfaces, which instrument is preferred for beta contamination?

• Geiger-Müller pancake probe designed for beta detection.
• Thermocouple.
• Optical spectrometer.
• Blood pressure cuff.

Correct Answer: Geiger-Müller pancake probe designed for beta detection.

Q26. Which radionuclide property most influences its suitability as a diagnostic tracer?

• Very long half-life of several years.
• Appropriate half-life, gamma emission energy suitable for detection and chemistry for labeling.
• Emission of high-LET alpha particles.
• Inability to bind to biological molecules.

Correct Answer: Appropriate half-life, gamma emission energy suitable for detection and chemistry for labeling.

Q27. What is an important safety consideration when handling alpha sources in the lab?

• Alpha particles require no containment because they travel far in air.
• Avoid ingestion or inhalation by using fume hoods and gloveboxes since internal alpha exposure is hazardous.
• Only shielding with thick lead is necessary for external alpha sources.
• Alpha sources can be handled without gloves because they are not ionizing.

Correct Answer: Avoid ingestion or inhalation by using fume hoods and gloveboxes since internal alpha exposure is hazardous.

Q28. Which factor determines the range of charged particles in tissue?

• Initial kinetic energy and stopping power of the material.
• Only the decay mode of the radionuclide.
• Ambient air pressure exclusively.
• Color of the shielding material.

Correct Answer: Initial kinetic energy and stopping power of the material.

Q29. Which of the following best describes pair production?

• Conversion of a gamma photon into an electron-positron pair near a nucleus when photon energy exceeds 1.022 MeV.
• Alpha emission producing two protons.
• Beta decay producing a neutron and a neutrino only.
• Photoelectric effect at low energies.

Correct Answer: Conversion of a gamma photon into an electron-positron pair near a nucleus when photon energy exceeds 1.022 MeV.

Q30. Which statement about daughter products in decay chains is relevant to pharmacy?

• Daughter products are always stable and non-radioactive.
• Daughter nuclides may have different radiological properties affecting safety and therapeutic effect; they must be considered in handling.
• Only the parent nuclide matters for dosimetry.
• Daughter products cannot be chemically separated from parent radionuclides.

Correct Answer: Daughter nuclides may have different radiological properties affecting safety and therapeutic effect; they must be considered in handling.

Q31. Which energy deposition pattern increases risk of DNA double-strand breaks?

• Low LET sparsely ionizing radiation like high-energy photons.
• High LET densely ionizing radiation like alpha particles.
• Non-ionizing radiation like visible light.
• Static magnetic fields.

Correct Answer: High LET densely ionizing radiation like alpha particles.

Q32. Which detector provides energy spectra useful for identifying gamma-emitting radionuclides?

• Scintillation detector coupled to a multichannel analyzer (e.g., NaI or HPGe).
• Simple Geiger counter with no spectral capability.
• Thermometer readout.
• pH indicator strip.

Correct Answer: Scintillation detector coupled to a multichannel analyzer (e.g., NaI or HPGe).

Q33. Which is a characteristic safety control to minimize occupational radiation dose?

• Time, distance and shielding principles.
• Increasing time spent near sources for familiarity.
• Avoiding monitoring of dose with badges.
• Using only visual inspection to assess contamination.

Correct Answer: Time, distance and shielding principles.

Q34. Why are alpha emitters less hazardous externally compared to internally?

• Because alpha particles do not ionize when outside the body.
• Alpha particles have very low penetration in air and dead skin, so external exposure is minimal, but internalized alpha emitters are highly damaging.
• Alpha emitters never emit radiation unless ingested.
• Alpha particles are absorbed by clothing and become harmless.

Correct Answer: Alpha particles have very low penetration in air and dead skin, so external exposure is minimal, but internalized alpha emitters are highly damaging.

Q35. Which process produces characteristic X-rays observed after electron capture?

• Electron capture leaves a vacancy in an inner shell; outer electrons fill vacancy emitting characteristic X-rays.
• Only gamma emission occurs with no X-rays.
• Beta decay produces identical characteristic X-rays.
• Neutron emission generates visible light only.

Correct Answer: Electron capture leaves a vacancy in an inner shell; outer electrons fill vacancy emitting characteristic X-rays.

Q36. What distinguishes Auger electrons from other emissions?

• They are high-energy gamma photons emitted by nucleus.
• They are low-energy electrons emitted when atomic shell vacancies are filled, often causing localized damage.
• They are neutrinos detected in PET scans.
• They are identical to alpha particles in LET and range.

Correct Answer: They are low-energy electrons emitted when atomic shell vacancies are filled, often causing localized damage.

Q37. Which of the following best explains why thin plastic shielding is preferred for some beta sources?

• Thin plastic reduces Bremsstrahlung compared to high-Z materials while stopping beta particles.
• Plastic generates more Bremsstrahlung than lead.
• Plastic cannot stop beta particles and is always ineffective.
• Plastic converts beta particles into gamma rays for easier detection.

Correct Answer: Thin plastic reduces Bremsstrahlung compared to high-Z materials while stopping beta particles.

Q38. In a mixed radiation field of gamma and beta, what is a correct shielding approach?

• Use only high-Z shielding; no other considerations needed.
• Provide low-Z material first to absorb beta and reduce Bremsstrahlung, then high-Z material for gamma attenuation as needed.
• Use no shielding but increase exposure time to average doses.
• Use only thin paper to block both radiations.

Correct Answer: Provide low-Z material first to absorb beta and reduce Bremsstrahlung, then high-Z material for gamma attenuation as needed.

Q39. Which describes the relationship between LET and RBE?

• Higher LET generally correlates with lower RBE.
• Higher LET generally correlates with higher RBE up to a certain point.
• LET and RBE are unrelated.
• Only gamma rays have measurable RBE.

Correct Answer: Higher LET generally correlates with higher RBE up to a certain point.

Q40. What is the primary advantage of using gamma emitters for imaging in nuclear medicine?

• Gamma emitters cannot be detected externally.
• Gamma photons can escape the body and be imaged with external detectors, allowing noninvasive imaging.
• Gamma emitters always cure disease without radiation damage.
• Gamma emitters are always alpha contaminants.

Correct Answer: Gamma photons can escape the body and be imaged with external detectors, allowing noninvasive imaging.

Q41. Which statement about decay constant (λ) and half-life (T1/2) is correct?

• λ = ln(2) / T1/2, so shorter half-life means larger decay constant.
• λ and T1/2 are unrelated.
• T1/2 increases as decay constant increases.
• Decay constant is measured in sieverts.

Correct Answer: λ = ln(2) / T1/2, so shorter half-life means larger decay constant.

Q42. Which radionuclide property is crucial for internal dosimetry calculations?

• Chemical color of radionuclide.
• Emission energies, branching ratios, half-life and biokinetics in the body.
• Only the activity in becquerels without considering energy.
• Ambient room temperature exclusively.

Correct Answer: Emission energies, branching ratios, half-life and biokinetics in the body.

Q43. Which statement about neutron radiation is correct relative to alpha, beta, gamma?

• Neutrons are charged particles like alpha and beta.
• Neutrons are uncharged and interact differently, often producing secondary charged particles; they require specialized shielding like hydrogen-rich materials.
• Neutrons are identical to gamma rays in interactions.
• Neutrons are non-ionizing and harmless.

Correct Answer: Neutrons are uncharged and interact differently, often producing secondary charged particles; they require specialized shielding like hydrogen-rich materials.

Q44. During handling of radiopharmaceuticals, what is the ALARA principle?

• Always Leave All Radiation Alone.
• As Low As Reasonably Achievable — minimize exposure by time, distance, shielding.
• Allow Limitless Acceptable Radiation Amounts.
• Apply Long Active Radiopharmaceuticals Aggressively.

Correct Answer: As Low As Reasonably Achievable — minimize exposure by time, distance, shielding.

Q45. Which factor increases the proportion of photoelectric effect relative to Compton scattering?

• Increasing photon energy to MeV range.
• Decreasing atomic number of absorber.
• Using high atomic number (Z) absorber and lower photon energy.
• Presence of vacuum only.

Correct Answer: Using high atomic number (Z) absorber and lower photon energy.

Q46. Which clinical scenario favors using a pure beta emitter for therapy?

• Targeting superficial skin lesions where deep penetration is required.
• Treating small to medium-sized tumors where localized electron range is therapeutic with minimal gamma contamination.
• When external imaging of dose distribution is mandatory without any other methods.
• When positron emission tomography imaging is needed.

Correct Answer: Treating small to medium-sized tumors where localized electron range is therapeutic with minimal gamma contamination.

Q47. What is the effect of increasing beam energy on Bremsstrahlung production for beta particles?

• Bremsstrahlung production decreases with increasing beta energy.
• Bremsstrahlung production increases with increasing beta energy and higher-Z materials.
• Beam energy has no effect on Bremsstrahlung.
• Bremsstrahlung is only produced by alpha particles.

Correct Answer: Bremsstrahlung production increases with increasing beta energy and higher-Z materials.

Q48. Which is a distinguishing detector response between alpha and beta particles in a scintillation detector?

• Alpha pulses typically produce larger light output per unit energy (higher scintillation efficiency) leading to pulse height discrimination from beta.
• Alpha and beta always produce identical pulse heights regardless of energy.
• Scintillation detectors cannot detect alpha radiation.
• Beta particles always produce larger pulses than alpha for same energy due to lower LET.

Correct Answer: Alpha pulses typically produce larger light output per unit energy (higher scintillation efficiency) leading to pulse height discrimination from beta.

Q49. Which describes secular equilibrium relevant to generator-produced radionuclides (e.g., 99Mo/99mTc)?

• The activity of parent and daughter are equal when the parent half-life is much shorter than the daughter.
• When parent half-life is much longer than daughter, daughter activity reaches a constant fraction of parent activity after several daughter half-lives.
• Secular equilibrium means no decay occurs.
• Secular equilibrium applies only to stable isotopes.

Correct Answer: When parent half-life is much longer than daughter, daughter activity reaches a constant fraction of parent activity after several daughter half-lives.

Q50. For occupational monitoring, what does a dosimeter worn on the chest primarily measure?

• External radiation dose to the trunk, approximating whole-body exposure relevant for regulatory dose limits.
• Internal alpha contamination exclusively.
• Airborne radionuclide concentration only.
• The color change of protective clothing.

Correct Answer: External radiation dose to the trunk, approximating whole-body exposure relevant for regulatory dose limits.