Radiation Health Effects — MCQs
In an accident case, after the arrival of medical team, all should be done in early management except;
Cell most sensitive to radiation –
Dose of radiation during whole body exposure that leads to hematopoietic syndrome is:
Which radioisotope is commonly used in teletherapy?
A pregnant woman with head trauma requires a CT scan of the head. What is the most effective radiation protection measure for the fetus?
Which of the following is most radioresistant?
X-rays cause radiation damage primarily by their property of:
Which of the following is a stochastic effect of radiation?
Late effects of radiation therapy include:
Which of the following methods is considered safe for disposal and beneficial for soil building?
Radiation Health Effects Indian Medical PG Practice Questions and MCQs
Question 1: In an accident case, after the arrival of medical team, all should be done in early management except;
- A. Glasgow coma scale
- B. Check BP (Correct Answer)
- C. Stabilization of cervical vertebrae
- D. Check Respiration
Explanation: ***Check BP*** - In the **immediate/early management** of trauma (primary survey), while circulation assessment is crucial, the **initial assessment of circulation** focuses on: - **Pulse rate and quality** (radial, carotid) - **Capillary refill time** - **Skin color and temperature** - **Active hemorrhage control** - **Formal blood pressure measurement** with a cuff, while important, is typically recorded during or after these rapid initial assessments, as it takes more time to obtain an accurate reading. - In the context of this question, among the four options listed, BP measurement is relatively less immediate compared to the other life-saving priorities (airway protection, breathing assessment, C-spine stabilization, and GCS). - **Note:** This is a nuanced distinction - BP is assessed during primary survey, but the other three options have more immediate life-threatening implications if not addressed. *Glasgow coma scale* - **GCS assessment** is part of the **"D" (Disability)** step in the ATLS primary survey. - It is performed early to assess neurological status and level of consciousness. - GCS <8 indicates need for **definitive airway protection** (intubation). - This is a critical early assessment that guides immediate management decisions. *Stabilization of cervical vertebrae* - **C-spine immobilization** is part of the **"A" (Airway)** step - "Airway with cervical spine protection." - It is performed **simultaneously** with airway assessment using a **rigid cervical collar**. - This is the **first priority** in trauma management to prevent secondary spinal cord injury. - All trauma patients should be assumed to have C-spine injury until proven otherwise. *Check Respiration* - **Respiratory assessment** is part of the **"B" (Breathing)** step in the ATLS primary survey. - This involves checking: - **Respiratory rate and pattern** - **Chest wall movement** - **Air entry bilaterally** - **Signs of tension pneumothorax or flail chest** - This is an immediate life-saving priority and must be assessed early.
Question 2: Cell most sensitive to radiation –
- A. Lymphocytes (Correct Answer)
- B. Platelets
- C. Neutrophils
- D. Basophils
Explanation: ***Lymphocytes*** - **Lymphocytes** are the most sensitive hematopoietic cells to radiation due to their rapid turnover and intrinsic radiosensitivity [1]. - Exposure to even low doses of radiation can lead to rapid **apoptosis** and a decrease in lymphocyte count. *Platelets* - **Platelets** are relatively radioresistant, and their numbers decrease more slowly after radiation exposure compared to lymphocytes. - The primary impact on platelets is often indirect, affecting their production by **megakaryocytes** which are also somewhat radioresistant. *Neutrophils* - **Neutrophils** are more radiosensitive than platelets but less so than lymphocytes. Their numbers typically decline after lymphocytes but before red blood cells [2]. - The lifespan of neutrophils is relatively short, and radiation primarily affects the **myeloid precursors** in the bone marrow [2]. *Basophils* - **Basophils** are present in low numbers in the blood and their radiosensitivity is not as well-documented as other white blood cells. - While sensitive, they are generally considered less radiosensitive than lymphocytes. **References:** [1] Cross SS. Underwood's Pathology: A Clinical Approach. 6th ed. (Basic Pathology) introduces the student to key general principles of pathology, both as a medical science and as a clinical activity with a vital role in patient care. Part 2 (Disease Mechanisms) provides fundamental knowledge about the cellular and molecular processes involved in diseases, providing the rationale for their treatment. Part 3 (Systematic Pathology) deals in detail with specific diseases, with emphasis on the clinically important aspects., pp. 111-112. [2] Cross SS. Underwood's Pathology: A Clinical Approach. 6th ed. (Basic Pathology) introduces the student to key general principles of pathology, both as a medical science and as a clinical activity with a vital role in patient care. Part 2 (Disease Mechanisms) provides fundamental knowledge about the cellular and molecular processes involved in diseases, providing the rationale for their treatment. Part 3 (Systematic Pathology) deals in detail with specific diseases, with emphasis on the clinically important aspects., pp. 112-113.
Question 3: Dose of radiation during whole body exposure that leads to hematopoietic syndrome is:
- A. 10 Gy
- B. 200 Gy
- C. 100 Gy
- D. 2 Gy (Correct Answer)
Explanation: ***2 Gy*** - A whole-body radiation dose of **2 Gy** (200 rads) is generally considered the threshold for the development of the **hematopoietic syndrome**, one of the acute radiation syndromes. - This dose causes significant damage to the **bone marrow**, leading to a decrease in the production of blood cells, which can become life-threatening. *10 Gy* - A dose of **10 Gy** (1000 rads) typically leads to the **gastrointestinal syndrome**, which involves severe damage to the gastrointestinal lining. - While hematopoietic effects would also be severe at this dose, the predominant and more rapidly fatal syndrome is gastrointestinal, with survival unlikely even with intensive supportive care. *200 Gy* - A dose of **200 Gy** (20,000 rads) causes the **cerebrovascular (central nervous system) syndrome**, leading to rapid incapacitation and death within hours or days. - At this extreme dose, brain swelling, vasculitis, and neuronal damage are immediate and overwhelming. *100 Gy* - A dose of **100 Gy** (10,000 rads) also falls within the range causing the **cerebrovascular (central nervous system) syndrome**. - This level of exposure results in rapid onset of neurological symptoms and quickly leads to death due to cellular damage in the brain.
Question 4: Which radioisotope is commonly used in teletherapy?
- A. Ra-226
- B. Cs-137
- C. Co-60 (Correct Answer)
- D. Ir-192
Explanation: ***Co-60*** - **Cobalt-60** is a widely used radioisotope in teletherapy (external beam radiotherapy) due to its high-energy gamma emissions (1.17 and 1.33 MeV). - Its relatively long half-life of **5.27 years** makes it practical for sustained clinical use in **teletherapy units**. *Ra-226* - **Radium-226** was historically used in brachytherapy but has largely been replaced due to its alpha emissions, which are difficult to shield, and its long-lived radioactive decay products. - Its use for teletherapy is **not common** because of these safety concerns and the availability of more suitable isotopes. *Cs-137* - **Cesium-137** is primarily used in **brachytherapy** and some low-dose rate teletherapy machines for specific applications, but not as commonly as Co-60 for general teletherapy. - Its lower gamma energy (0.662 MeV) and shorter half-life than Co-60 (30.17 years) make it less ideal for the widespread **deep penetration** required in many teletherapy treatments. *Ir-192* - **Iridium-192** is predominantly used in **high-dose-rate (HDR) brachytherapy** for temporary implants, delivering radiation over short periods. - Its relatively short half-life of **73.8 days** and lower average gamma energy make it unsuitable for typical long-term teletherapy external beam applications.
Question 5: A pregnant woman with head trauma requires a CT scan of the head. What is the most effective radiation protection measure for the fetus?
- A. Using MRI instead
- B. Lead apron over abdomen
- C. Avoid CT, rely on clinical assessment
- D. Reduced mA and kVp (Correct Answer)
Explanation: ***Reduced mA and kVp*** - **Optimizing scan parameters** (reducing mA and kVp) is the most effective way to minimize radiation dose during head CT in pregnancy. - Modern CT scanners with **iterative reconstruction** allow significant dose reduction without compromising diagnostic image quality. - The fetal dose from head CT is already negligible (< 0.01 mGy), but dose optimization further reduces any potential risk. - This directly addresses the radiation source rather than attempting to shield scatter radiation. *Lead apron over abdomen* - Lead shielding provides **minimal to no benefit** during head CT as the fetus is far from the primary beam. - Scatter radiation reaching the pelvis from head CT is negligible. - Lead aprons can interfere with **automatic exposure control (AEC)**, potentially increasing rather than decreasing dose. - Modern radiology guidelines (ACR, ICRP) no longer routinely recommend gonadal shielding for most CT examinations. *CT not recommended* - Withholding indicated imaging in trauma is **inappropriate and potentially dangerous**. - The diagnostic benefit of head CT in trauma far outweighs the negligible fetal risk. - **Maternal well-being** is the priority, and missing a critical head injury poses greater risk to both mother and fetus. *Using MRI instead* - While MRI has no ionizing radiation, it is **not appropriate for acute trauma** evaluation. - MRI takes longer to perform, requires patient cooperation, and is less readily available in emergency settings. - CT remains the **gold standard** for acute head trauma assessment.
Question 6: Which of the following is most radioresistant?
- A. Cartilage (Correct Answer)
- B. Ewing's sarcoma
- C. GIT epithelium
- D. Gonadal tumours
Explanation: ***Cartilage*** - **Cartilage** is a connective tissue with a relatively **low metabolic rate** and **avascular nature**, making its cells (chondrocytes) less susceptible to rapid turnover and DNA damage from radiation. - Its **dense extracellular matrix** and limited cellular division contribute to its inherent resistance to ionizing radiation, requiring higher doses to induce significant damage. *Ewing's sarcoma* - **Ewing's sarcoma** is a highly **malignant bone tumor** that is generally considered **radiosensitive** and often treated with radiation therapy. - Its cells are rapidly dividing, making them more vulnerable to the DNA-damaging effects of radiation. *GIT epithelium* - The **gastrointestinal tract (GIT) epithelium** is characterized by **rapid cell turnover** and high mitotic activity to constantly replace damaged cells and absorb nutrients. - This high proliferative rate makes the GIT epithelium highly **radiosensitive**, leading to common side effects like mucositis and diarrhea during radiation therapy. *Gonadal tumours* - Tumors of the **gonads** (e.g., testicular seminoma, ovarian dysgerminoma) are often highly **radiosensitive** and respond well to radiation therapy due to the germ cell origin and rapid proliferation of tumor cells. - The germ cells themselves are very sensitive to radiation, leading to concerns about **fertility preservation** in patients undergoing treatment.
Question 7: X-rays cause radiation damage primarily by their property of:
- A. Radioactivity
- B. Penetration
- C. Electromagnetic induction
- D. Ionisation (Correct Answer)
Explanation: ***Correct: Ionisation*** - X-rays are a form of **ionising radiation**, meaning they have sufficient energy to **remove electrons from atoms**. - This process creates **ions** and free radicals, which can damage DNA and other cellular components, leading to radiation damage. *Incorrect: Radioactivity* - **Radioactivity** refers to the spontaneous emission of radiation from unstable atomic nuclei, a property of certain isotopes, not X-rays themselves. - While radioactive substances can emit various forms of radiation, including X-rays, the X-ray's damaging property is its ability to ionise, not its origin from a radioactive source directly. *Incorrect: Penetration* - The **penetrating power** of X-rays allows them to pass through tissues and is essential for imaging, but it is not the direct mechanism of biological damage. - Their ability to pass through matter facilitates interaction with atoms throughout the body, making ionisation possible. *Incorrect: Electromagnetic induction* - **Electromagnetic induction** is the production of an electromotive force across an electrical conductor in a changing magnetic field, a principle used in generators and transformers. - This phenomenon is unrelated to the biological effects or primary mechanism of radiation damage from X-rays.
Question 8: Which of the following is a stochastic effect of radiation?
- A. Alopecia in the irradiated portal
- B. Local desquamation in the irradiated field
- C. Genetic mutation (Correct Answer)
- D. All of the options
Explanation: ***Genetic mutation*** - **Stochastic effects** are those for which the probability of occurrence, rather than the severity, is a function of radiation dose without a threshold. **Genetic mutations** are a classic example, as any dose carries some probability of inducing a change in DNA that can be passed to offspring. - The severity of a genetic mutation, if it occurs, is independent of the dose. It's the chance of it happening that increases with exposure. *Alopecia in the irradiated portal* - **Alopecia** (hair loss) due to radiation is a **deterministic effect**, meaning there is a threshold dose below which it does not occur, and above that threshold, the severity increases with dose. - It occurs locally in the **irradiated field** because it is a direct tissue reaction to cellular damage. *Local desquamation in the irradiated field* - **Desquamation** (skin peeling) is a **deterministic effect** that results from direct cell death and damage in the skin, a tissue reaction with a dose threshold. - Its occurrence and severity are directly related to the **radiation dose received** in the specific area. *All of the options* - This option is incorrect because **alopecia** and **desquamation** are deterministic effects, not stochastic effects. - Only **genetic mutation** falls under the category of stochastic effects among the choices provided.
Question 9: Late effects of radiation therapy include:
- A. Mucositis, Enteritis, Nausea and vomiting, Pneumonitis
- B. Enteritis, Nausea and vomiting, Pneumonitis, Somatic mutations
- C. Mucositis, Nausea and vomiting, Pneumonitis, Somatic mutations
- D. Mucositis, Enteritis, Pneumonitis, Somatic mutations (Correct Answer)
Explanation: ***Mucositis, Enteritis, Pneumonitis, Somatic mutations*** - **Somatic mutations** leading to **secondary malignancies** are a classic late effect of radiation (occurs years after exposure due to DNA damage) [1] - **Radiation pneumonitis** progressing to **pulmonary fibrosis** is a well-recognized late complication (typically 1-3 months to years post-treatment) [1] - **Chronic radiation enteritis** with fibrosis and vascular damage can occur months to years after abdominal/pelvic radiation [1] - **Chronic mucositis** with fibrosis can persist as a late effect, though mucositis is more commonly acute - This option represents the **most comprehensive list of late effects** among the choices *Mucositis, Enteritis, Nausea and vomiting, Pneumonitis* - **Nausea and vomiting** are predominantly **acute side effects** occurring during or immediately after radiation therapy, not late effects - While mucositis and enteritis can have chronic forms, including nausea/vomiting makes this option incorrect *Enteritis, Nausea and vomiting, Pneumonitis, Somatic mutations* - Incorrectly includes **nausea and vomiting** as a late effect - Though it includes somatic mutations (correct late effect), the presence of an acute symptom invalidates this choice *Mucositis, Nausea and vomiting, Pneumonitis, Somatic mutations* - Incorrectly includes **nausea and vomiting** as a late effect - Omits enteritis, which can manifest as chronic radiation enteritis with fibrosis and strictures **References:** [1] Kumar V, Abbas AK, et al.. Robbins and Cotran Pathologic Basis of Disease. 9th ed. Central Nervous System Synapse, pp. 437-439.
Question 10: Which of the following methods is considered safe for disposal and beneficial for soil building?
- A. Controlled tipping
- B. Incineration
- C. Composting (Correct Answer)
- D. None of the options
Explanation: ***Composting*** - **Composting** is a natural biological process where organic matter decomposes under controlled conditions, producing **humus** which is beneficial for soil. - It effectively reduces waste volume, enriches soil structure and fertility, and sequesters **carbon**, making it an environmentally sound disposal and soil-building method. *Incineration* - **Incineration** involves burning waste at high temperatures, significantly reducing its volume and sometimes generating energy. - However, it produces **ash** that requires landfill disposal and can release **air pollutants** and greenhouse gases, making it not beneficial for soil building. *Controlled tipping* - **Controlled tipping**, also known as **sanitary landfilling**, involves depositing waste in an engineered site, compacting it, and covering it daily. - While it attempts to minimize environmental impact compared to open dumping, it does not build soil and can still lead to **leachate** formation and **greenhouse gas emissions**. *None of the options* - This option is incorrect because **composting** is a well-established method that is both safe for disposal and beneficial for soil building.
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