Radiation Accidents Management — MCQs
Dose of radiation during whole body exposure that leads to hematopoietic syndrome is:
Radiotherapy has the most significant therapeutic role in:
Bleeding crisis in acute idiopathic thrombo-cytopenic purpura is managed by all except -
24 yr old mother with 7 week POG presents to ANC OPD with accidental low-dose radiation exposure. What is the most appropriate immediate management?
Which of the following radioactive isotopes is not used for brachytherapy?
A pregnant woman with head trauma requires a CT scan of the head. What is the most effective radiation protection measure for the fetus?
All are done to minimize radiation exposure to the patient under fluoroscopy, except which of the following?
A 28-year-old male patient presents with colicky abdominal pain along with vomiting. X-ray abdomen shows:
The Doppler effect results from a change in what property of sound?
Who discovered X-rays?
Radiation Accidents Management Indian Medical PG Practice Questions and MCQs
Question 1: 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 2: Radiotherapy has the most significant therapeutic role in:
- A. Monoclonal gammopathy
- B. Tuberculosis
- C. Sarcomas (Correct Answer)
- D. Sarcoidosis
Explanation: ***Sarcomas*** - **Radiotherapy** plays a crucial therapeutic role in **sarcomas**, though typically as **adjuvant therapy** combined with surgical resection - Used for **local control** in soft tissue sarcomas, particularly when wide margins cannot be achieved - **Primary radiotherapy** is the treatment of choice for certain radiation-sensitive sarcomas like **Ewing's sarcoma** and in cases of **inoperable tumors** - Essential for reducing **local recurrence rates** in high-grade soft tissue sarcomas - Among the options listed, sarcomas have the **strongest and most established indication** for radiotherapy *Monoclonal gammopathy* - Generally **observation only** for MGUS (Monoclonal Gammopathy of Undetermined Significance) - Radiotherapy used only for **solitary plasmacytoma**, which is a specific localized manifestation - Multiple myeloma (if it progresses) is treated with **chemotherapy** and targeted agents, not radiotherapy as primary treatment *Tuberculosis* - An **infectious disease** caused by *Mycobacterium tuberculosis* - Treated exclusively with **anti-tubercular drug regimens** (RIPE: Rifampicin, Isoniazid, Pyrazinamide, Ethambutol) - Radiotherapy has **no role** in treating infections *Sarcoidosis* - A **systemic inflammatory condition** with non-caseating granulomas - Primary treatment is **corticosteroids** for symptomatic cases - Immunosuppressants used for refractory cases - Radiotherapy has **no role** in inflammatory/granulomatous diseases
Question 3: Bleeding crisis in acute idiopathic thrombo-cytopenic purpura is managed by all except -
- A. Intravenous immunoglobulin
- B. Prednisolone
- C. Eltrombopag (Correct Answer)
- D. RhIG
Explanation: ***Eltrombopag*** - **Eltrombopag** is a **thrombopoietin receptor agonist** used for chronic idiopathic thrombocytopenic purpura (ITP) to increase platelet production. - It is **not** used for the immediate management of an acute bleeding crisis, as its effects on platelet counts take several days to manifest. *Intravenous immunoglobulin* - **Intravenous immunoglobulin (IVIG)** works by blocking **Fc receptors** on macrophages, thereby reducing the destruction of antibody-coated platelets. - It is a **first-line treatment** for acute ITP, especially in cases with severe bleeding or very low platelet counts, providing a rapid increase in platelet count. *Prednisolone* - **Prednisolone**, a corticosteroid, is a **first-line treatment** for acute ITP, as it suppresses the immune system and reduces antibody production and platelet destruction. - It helps to quickly raise platelet counts and is effective in managing bleeding episodes, though its effects are not as immediate as IVIG. *RhIG* - **Rh immune globulin (RhIG)** is used in **Rh-positive** patients with ITP to cause a transient hemolytic anemia, which occupies splenic macrophages and reduces platelet destruction. - It `is an effective option` for acute ITP, particularly in patients who require a rapid increase in platelet count and are Rh-positive.
Question 4: 24 yr old mother with 7 week POG presents to ANC OPD with accidental low-dose radiation exposure. What is the most appropriate immediate management?
- A. Reassure and continue pregnancy (Correct Answer)
- B. Perform detailed fetal anomaly scan
- C. Advise medical termination of pregnancy
- D. Advise genetic counseling and testing
Explanation: ***Reassure and continue pregnancy*** - **Low-dose radiation exposure** (typically defined as <50 mGy) during pregnancy is generally associated with a very low risk of fetal anomalies or adverse outcomes. The patient should be reassured that the risk to the fetus is minimal. - The threshold for concern for teratogenic effects from radiation is significantly higher than a low dose, and **medical termination of pregnancy** is not indicated in such cases. - This is the most appropriate **immediate management** for accidental low-dose radiation exposure at 7 weeks gestation. *Perform detailed fetal anomaly scan* - While anomaly scans are part of routine prenatal care, performing an immediate, detailed scan solely due to **low-dose radiation exposure** at 7 weeks is not the most appropriate *immediate* management. The risk of anomalies from such exposure is extremely low and unlikely to be detectable at 7 weeks. - A more detailed scan may be considered at later gestational ages (e.g., 18-20 weeks) as part of standard care, but not as an emergency response to low-dose exposure. *Advise medical termination of pregnancy* - Medical termination is **not indicated** for accidental **low-dose radiation exposure**. Termination is only considered in cases of *extremely high* and confirmed doses (e.g., >100 mGy), which carry a significant risk of severe fetal anomalies or mortality. - Such high doses are rare in accidental exposures and would necessitate a thorough dose assessment by a radiation physicist before considering any drastic measures. - Since the scenario specifies low-dose exposure, termination would be inappropriate and potentially harmful counseling. *Advise genetic counseling and testing* - **Genetic counseling** and testing would be indicated for known genetic risks, advanced maternal age, or suspicion of chromosomal abnormalities, none of which are suggested by accidental **low-dose radiation exposure**. - Radiation-induced effects are typically teratogenic rather than directly causing inheritable genetic mutations that would be detected by standard genetic testing.
Question 5: Which of the following radioactive isotopes is not used for brachytherapy?
- A. Iodine-125
- B. Iridium-192
- C. Iodine-131 (Correct Answer)
- D. Cobalt-60
Explanation: ***Iodine-131*** - **Iodine-131** is primarily used for **systemic radionuclide therapy** due to its emission of **beta particles** and **gamma rays**, making it suitable for treating diffuse diseases like **thyroid cancer** and **hyperthyroidism**. - Its mechanism of action relies on systemic uptake rather than localized placement within or next to a tumor, which defines **brachytherapy**. *Iodine-125* - **Iodine-125** is a common isotope used in **low-dose-rate (LDR) brachytherapy**, particularly for **prostate cancer** and **ocular melanoma**. - It emits **low-energy gamma and X-rays**, providing highly localized radiation with a steep dose fall-off, minimizing damage to surrounding healthy tissue. *Iridium-192* - **Iridium-192** is widely used in **high-dose-rate (HDR) brachytherapy** for various cancers, including **cervical**, **prostate**, **breast**, and **skin cancers**. - It emits **gamma rays** and has a shorter half-life than Iodine-125, allowing for higher dose rates over shorter treatment durations. *Cobalt-60* - **Cobalt-60** was historically used in **brachytherapy** and **teletherapy** but has largely been replaced by newer isotopes for brachytherapy due to its high energies and larger source size. - While its use in brachytherapy has decreased, it is still employed in specific applications and **external beam radiation therapy (teletherapy)**.
Question 6: 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 7: All are done to minimize radiation exposure to the patient under fluoroscopy, except which of the following?
- A. Decreasing fluoroscopic time
- B. Increasing fluoroscopic time (Correct Answer)
- C. Using low dose of radiation
- D. Decrease in field of view
Explanation: ***Increasing fluoroscopic time*** - **Increasing fluoroscopic time** directly leads to a greater cumulative dose of radiation received by the patient. - This action goes against the principle of **ALARA (As Low As Reasonably Achievable)** for radiation safety. *Decreasing fluoroscopic time* - **Decreasing fluoroscopic time** reduces the total duration of X-ray exposure, thereby minimizing the radiation dose to the patient. - This is a fundamental practice in radiation protection. *Using low dose of radiation* - Employing **low-dose radiation protocols** means using the minimum amount of radiation necessary to obtain diagnostic images. - This directly reduces the patient's exposure while maintaining image quality for diagnosis. *Decrease in field of view* - A **decrease in the field of view** (collimation) restricts the X-ray beam to only the area of interest, limiting irradiation of surrounding healthy tissues. - This targeted approach significantly reduces the overall radiation dose to the patient.
Question 8: A 28-year-old male patient presents with colicky abdominal pain along with vomiting. X-ray abdomen shows:
- A. Pseudo-obstruction
- B. Cancer colon
- C. Small bowel obstruction (Correct Answer)
- D. Paralytic ileus
Explanation: ***Small bowel obstruction*** - The X-ray image shows multiple **dilated loops of small bowel** with **air-fluid levels** and prominent **valvulae conniventes** (herringbone pattern), which are classic signs of small bowel obstruction. - The clinical presentation of **colicky abdominal pain** and **vomiting** is highly consistent with a small bowel obstruction. *Pseudo-obstruction* - Pseudo-obstruction, or Ogilvie's syndrome, primarily affects the **large bowel**, leading to colonic dilation without a mechanical obstruction. - While it can cause abdominal pain and vomiting, the X-ray findings would typically show marked dilation of the colon rather than predominantly small bowel loops. *Cancer colon* - Colon cancer, if it causes obstruction, typically presents as a **large bowel obstruction**, with colonic dilation proximal to the tumor. - While severe cases could lead to cecal dilation and subsequent small bowel obstruction, the primary radiographic findings would focus on the colon. *Paralytic ileus* - Paralytic ileus, or adynamic ileus, involves generalized bowel dilation (both small and large bowel) due to **impaired peristalsis**, without mechanical obstruction. - Although it causes abdominal pain and vomiting, it usually presents with more continuous, less colicky pain, and the X-ray often shows gas in the colon, which is typically absent or minimal in a complete small bowel obstruction.
Question 9: The Doppler effect results from a change in what property of sound?
- A. Amplitude of sound
- B. Frequency of sound (Correct Answer)
- C. Direction of sound
- D. None of the above
Explanation: The **Doppler effect** is a fundamental principle in ultrasound physics, defined as the change in the observed **frequency** (or wavelength) of a wave when there is relative motion between the source of the sound and the receiver. ### **Explanation of the Correct Answer** In medical ultrasonography, the ultrasound probe acts as both the source and the receiver. When ultrasound waves strike moving targets (primarily **Red Blood Cells**), the reflected frequency shifts: * **Higher Frequency:** Occurs when blood flows **towards** the transducer (waves are compressed). * **Lower Frequency:** Occurs when blood flows **away** from the transducer (waves are stretched). The difference between the transmitted and received frequencies is called the **Doppler Shift**. This shift is directly proportional to the velocity of blood flow, allowing for hemodynamic assessment. ### **Why Other Options are Incorrect** * **Option A (Amplitude):** Amplitude refers to the loudness or height of the sound wave. While amplitude decreases as sound travels through tissue (attenuation), it is not the property altered by the relative motion of the source. * **Option C (Direction):** While the direction of blood flow determines whether the frequency shifts up or down, the Doppler effect itself is defined by the change in frequency, not the change in the path of the sound wave. ### **High-Yield Clinical Pearls for NEET-PG** * **The Doppler Equation:** $\Delta f = \frac{2 \cdot f_0 \cdot v \cdot \cos\theta}{c}$ (where $\theta$ is the angle of insonation). * **Optimal Angle:** The Doppler shift is maximal when the ultrasound beam is parallel to flow ($\theta = 0^\circ$). In clinical practice, an angle of **$\leq 60^\circ$** is required for accurate velocity measurements. * **Aliasing:** A common artifact in Color or Pulsed Wave Doppler where high velocities exceed the **Nyquist limit** (1/2 of the Pulse Repetition Frequency), causing the flow to appear in the opposite color/direction. * **Power Doppler:** Detects the *amplitude* of the shift rather than the frequency shift itself; it is more sensitive for slow flow but does not show direction.
Question 10: Who discovered X-rays?
- A. Roentgen (Correct Answer)
- B. Madam Curie
- C. Becquerel
- D. Hounsfield
Explanation: **Explanation:** **Wilhelm Conrad Roentgen** discovered X-rays on **November 8, 1895**, while experimenting with Crookes tubes (vacuum tubes). He observed that a screen coated with barium platinocyanide began to fluoresce even when the tube was covered. He famously captured the first medical X-ray of his wife’s hand. For this monumental discovery, he was awarded the first-ever **Nobel Prize in Physics in 1901**. **Analysis of Incorrect Options:** * **Madam Curie:** Known for her pioneering research on radioactivity. She discovered the elements **Polonium and Radium** and coined the term "radioactivity." * **Henri Becquerel:** Discovered **spontaneous radioactivity** in 1896. The SI unit of radioactivity (Becquerel, Bq) is named after him. * **Godfrey Hounsfield:** Developed the first commercially viable **Computed Tomography (CT) scanner** in 1972. The "Hounsfield Unit" (HU) is the standard scale for measuring radiodensity in CT scans. **High-Yield Clinical Pearls for NEET-PG:** * **X-ray Properties:** They are electromagnetic waves with high frequency and short wavelength. They travel in straight lines at the speed of light and are not deflected by magnetic or electric fields. * **Unit of Exposure:** The **Roentgen (R)** is the traditional unit used to measure ionizing radiation exposure in air. * **International Day of Radiology:** Celebrated on **November 8th** every year to commemorate Roentgen’s discovery. * **Biological Effects:** X-rays are ionizing radiation; the most sensitive phase of the cell cycle to radiation is the **M (Mitosis) phase**, followed by the G2 phase.
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