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RD3.1-4 | Radiation Safety and Legal Requirements — Graded Quiz
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A patient receives an absorbed dose of 2 Gy of X-rays to a localised tissue volume. Which statement about the relationship between absorbed dose and biological effect is correct?
Correct. Absorbed dose (Gy) is the physical energy deposited per unit mass. Applying radiation- and tissue-weighting factors converts it into equivalent and effective dose (Sv), which express biological harm.
Absorbed dose (Gy) is physical; equivalent/effective dose (Sv) applies weighting for radiation type and tissue sensitivity to reflect harm.
Gray measures the physical energy deposited only; the biological weighting that gives sieverts is a separate step. The two are not interchangeable units.
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A whole-body acute exposure produces nausea, vomiting and bone-marrow suppression within days. How should these acute radiation syndrome features be classified, and what does this imply about dose?
Correct. Acute radiation syndrome is a deterministic (tissue-reaction) effect: it appears only above a threshold dose and its severity increases with dose, indicating a substantial exposure occurred.
Acute radiation syndrome is deterministic: threshold exists, severity is dose-dependent. Contrast with stochastic carcinogenesis (no threshold, probability-driven).
ARS is the prototype acute deterministic effect with a clear threshold and dose-dependent severity, not a no-threshold stochastic effect.
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When interpreting a worker's TLD badge report, what does the recorded value represent?
Correct. A TLD integrates dose over the wear period; on read-out it reports the total cumulative dose received by the badge during that monitoring interval.
TLD reports cumulative personal dose over the monitoring period, not instantaneous dose rate. It is the standard for tracking occupational exposure over time.
A TLD is an integrating dosimeter; it does not show instantaneous rate or activity. Its value is the cumulative personal dose for the period.
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What is the recommended occupational effective-dose limit for a radiation worker in India, as adopted by the AERB?
Correct. The occupational limit is 20 mSv per year averaged over a 5-year period. The public limit is 1 mSv per year. These limits do not apply to diagnostic patient doses.
Occupational limit = 20 mSv/yr (5-yr average); public limit = 1 mSv/yr. Dose limits do NOT cap diagnostic patient dose, which is governed by justification and ALARA.
1 mSv/year is the limit for the general public. The occupational limit is 20 mSv/year (5-year average), and limits are expressed in sieverts, not gray.
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A junior doctor asks whether the 20 mSv/year occupational limit can be used to decide how much radiation a patient may receive from a justified CT scan. What is the correct reply?
Correct. Statutory dose limits protect workers and the public; they deliberately do not cap a patient's justified diagnostic dose. Patient dose is controlled by justification of the request and optimisation (ALARA).
Dose limits (20 mSv/yr occupational, 1 mSv/yr public) do NOT cap patient diagnostic dose. Patient exposure is controlled by justification + ALARA optimisation.
Dose limits do not apply to patients undergoing justified medical exposure. Patient protection works through justification and optimisation, not a numerical cap.
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In a mobile radiography exposure on a ward, which single action most effectively reduces the radiographer's dose, consistent with the ALARA triad?
Correct. Maximising distance (leveraging the inverse-square law) plus shielding with a lead apron applies two of the three ALARA methods and gives the greatest dose reduction in this setting.
ALARA triad = time, distance, shielding. Distance is especially powerful via the inverse-square law; lead-apron shielding adds further protection.
Standing close, increasing time, removing shielding or repeating exposures all INCREASE dose. The ALARA methods are minimise time, maximise distance, use shielding.
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Which statement correctly distinguishes the roles of the ICRP and the AERB in radiation protection?
Correct. The ICRP produces advisory recommendations adopted worldwide; the AERB, under the Atomic Energy Act 1962, gives them statutory force and enforces them in India.
ICRP = international advisory recommendations. AERB = Indian statutory regulator (Atomic Energy Act 1962) that enforces radiation protection.
The ICRP is advisory only and not Indian; enforcement in India is the AERB's role under the Atomic Energy Act 1962.
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Which document must, by law under the PC-PNDT Act, be completed and maintained for every prenatal diagnostic procedure performed at a registered ultrasound clinic?
Correct. Form F is the mandatory record under the PC-PNDT Act, documenting the indication and details of every prenatal diagnostic procedure. Clinics must also be registered and display the prescribed signage prohibiting sex determination.
PC-PNDT compliance for a primary-care physician: refer only to registered clinics, ensure Form F is completed, never request or disclose foetal sex, and note the mandatory anti-sex-determination signage.
TLD reports and AERB certificates relate to radiation safety, not PC-PNDT. The Act mandates Form F for every prenatal diagnostic procedure; disclosure of foetal sex is prohibited, never consented to.
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