CTBS Sterilization Methods 2 — Questions and Answers
Question 1: Which sterilization parameter is measured by a Biological Indicator (BI) containing Geobacillus stearothermophilus spores?
- Ethylene oxide efficacy
- Gamma radiation dose
- Steam sterilization efficacy (Correct answer)
- Dry heat sterilization
Correct answer: Steam sterilization efficacy
G. stearothermophilus spores are the standard BI for steam (autoclave) sterilization validation.
Question 2: What is the primary mechanism by which gamma radiation achieves sterilization?
- Oxidation of lipid membranes
- DNA strand breaks and free radical generation (Correct answer)
- Protein denaturation by heat
- Disruption of cell wall synthesis
Correct answer: DNA strand breaks and free radical generation
Gamma radiation kills microorganisms by inducing DNA damage through direct ionization and reactive free radicals.
Question 3: A tissue bank uses electron beam (e-beam) sterilization. Which feature distinguishes e-beam from gamma radiation?
- Higher penetration depth
- Lower dose uniformity ratio
- Much faster processing time (Correct answer)
- Greater efficacy against prions
Correct answer: Much faster processing time
E-beam processing is significantly faster than gamma because it uses accelerated electrons rather than isotope decay.
Question 4: During ETO sterilization, which post-processing step is mandatory before tissue release?
- UV irradiation for residual neutralization
- Aeration to remove ETO residuals (Correct answer)
- Rinse with sterile water
- Exposure to ozone
Correct answer: Aeration to remove ETO residuals
Aeration is required after ETO sterilization to reduce toxic residual ethylene oxide to safe levels.
Question 5: A Sterility Assurance Level (SAL) of 10⁻⁶ means:
- One in a million units may harbor a viable microorganism (Correct answer)
- One million spores are used in validation
- Six logs of bioburden reduction are not required
- The process uses 1 microgram of sterilant per unit
Correct answer: One in a million units may harbor a viable microorganism
SAL 10⁻⁶ means there is no more than a 1-in-1,000,000 probability that a single viable microorganism remains on a sterilized item.
Question 6: Which tissue type is MOST sensitive to gamma radiation-induced collagen degradation?
- Cortical bone
- Demineralized bone matrix (DBM)
- Soft tissue tendons and ligaments (Correct answer)
- Cancellous bone chips
Correct answer: Soft tissue tendons and ligaments
Soft tissue grafts like tendons and ligaments are particularly vulnerable to radiation-induced collagen cross-linking and structural weakening.
Question 7: What is the purpose of a dose-mapping study in radiation sterilization?
- To determine the biological indicator population
- To identify minimum and maximum dose points within a product load (Correct answer)
- To calibrate the ETO chamber pressure sensors
- To validate autoclave temperature uniformity
Correct answer: To identify minimum and maximum dose points within a product load
Dose mapping identifies the minimum and maximum radiation dose locations within the product configuration to ensure the entire load receives a sterilizing dose.
CTBS Sterilization Methods 2
Which sterilization parameter is measured by a Biological Indicator (BI) containing Geobacillus stearothermophilus spores?