NEET-PG 2020 - Radiology Practice Questions

Q: The Figure of 3 sign on chest X-ray is seen in which condition?

Coarctation of the Aorta. ***Coarctation of the Aorta*** - The **Figure of 3 sign** is a classic radiographic finding in coarctation of the aorta, representing pre- and post-stenotic dilatation along with the indentation of the coarctation itself. - This sign is often accompanied by **rib notching** due to collateral circulation, seen on chest X-ray. *Transposition of the Great Arteries* - Characteristically presents with a **"egg-on-a-string" appearance** on chest X-ray due to a narrow mediastinum and cardiomegaly. - This condition involves the great arteries being **switched**, leading to separate systemic and pulmonary circulations. *Mitral Stenosis* - Chest X-ray findings typically include **left atrial enlargement**, which can cause a "double density" sign or splaying of the carina. - Other findings might include **pulmonary venous hypertension** and kerley B lines, not the Figure of 3 sign. *Aortic Stenosis* - Can cause **post-stenotic dilatation of the ascending aorta**, but it does not produce the characteristic Figure of 3 sign. - Severe aortic stenosis might show **left ventricular hypertrophy** on ECG or echocardiography, but not clearly on a standard chest X-ray.

Q: Radiation Dose Monitoring in Occupational Workers is done by

TLD Badge. ***TLD Badge (used for monitoring radiation exposure)*** - **Thermoluminescent Dosimeter (TLD) badges** are widely used for monitoring an individual's exposure to ionizing radiation over time. - They work by storing energy from radiation exposure and releasing it as **light when heated**, which is then measured to calculate the accumulated dose. *Collimators (used to shape radiation beams)* - **Collimators** are devices used in radiation therapy and diagnostic imaging to **restrict and shape the radiation beam**, ensuring it only targets the intended area. - They do not measure or monitor the dose received by an individual, but rather **control the spatial distribution** of the radiation. *Grid (used to reduce scatter in imaging)* - An **anti-scatter grid** is placed between the patient and the image receptor in radiography to **absorb scattered radiation**, which degrades image quality. - While essential for image quality, grids do not directly measure or monitor the radiation dose received by an occupational worker. *Linear Accelerator (used for delivering radiation therapy)* - A **linear accelerator (linac)** is a machine used to deliver **external beam radiation treatment** for cancer. - It generates high-energy X-rays or electrons, but it is a **source of radiation** for treatment, not a device for monitoring occupational exposure.

Q: Which radiotherapy technique involves the use of remote afterloading to deliver radiation directly to the tumor?

Brachytherapy. ***Correct: Brachytherapy*** - **Remote afterloading** is a hallmark of modern brachytherapy, where radioactive sources are automatically advanced into catheters placed within or near the tumor. - This technique allows for the delivery of a **high dose of radiation directly to the tumor** while sparing surrounding healthy tissues. - Examples include **intracavitary** (cervical cancer), **interstitial** (prostate cancer), and **intraluminal** (esophageal cancer) brachytherapy. *Incorrect: External Beam Radiotherapy* - This technique involves delivering radiation from a machine **outside the body** to target a tumor. - It does not involve the direct placement of radioactive sources within the patient or the use of **remote afterloading**. *Incorrect: Stereotactic Radiotherapy* - While a precise form of external beam radiotherapy using focused beams, it still involves an **external source** of radiation. - It does not utilize internal radioactive sources or **afterloading techniques**. *Incorrect: Proton Beam Radiotherapy* - This is an advanced form of external beam radiotherapy that uses **protons instead of photons** to deliver radiation with high precision. - It does not involve the placement of radioactive sources within the patient or the use of **remote afterloading**.

Q: A 7-week pregnant lady underwent a chest X-ray by mistake. What is to be done?

Reassure the patient and continue the pregnancy.. **Reassure the patient and continue the pregnancy.** - A single chest X-ray delivers a **negligible dose of radiation (around 0.01 mGy)** to the embryo/fetus, which is significantly below the threshold for causing congenital abnormalities or pregnancy loss. - The **teratogenic threshold** for radiation exposure is generally considered to be around **50-100 mGy**, making a single chest X-ray exposure well within safe limits. *Terminate the pregnancy immediately due to radiation exposure.* - There is **no clinical justification** for pregnancy termination based on a single chest X-ray, as the radiation dose is far too low to cause significant harm. - Such an intervention would be based on **misinformation** and could lead to unnecessary emotional distress and ethical concerns. *Perform chromosomal testing to assess fetal damage.* - Chromosomal testing is **not indicated** for low-dose radiation exposure from a single chest X-ray, as this type of exposure is unlikely to cause chromosomal abnormalities. - The radiation dose is simply too low to inflict the kind of damage that would necessitate such invasive and often risky procedures. *Conduct prenatal invasive diagnostic tests to evaluate fetal health.* - Invasive prenatal diagnostic tests, such as **amniocentesis or chorionic villus sampling**, carry their own risks and are not warranted for a benign exposure like a chest X-ray. - These tests are typically reserved for situations with a much higher established risk of fetal anomalies.

Q: Cancer patient undergoes radiotherapy, pick the true statement for radiosensitivity of tissues?

Small blood vessels are radiosensitive tissues. ***Small blood vessels are radiosensitive tissues*** - **Endothelial cells** lining small blood vessels are actively dividing and have a relatively short lifespan, making them susceptible to radiation-induced damage. - Damage to these vessels can lead to **fibrosis** and **tissue hypoxia**, contributing to late radiation effects. *GI mucosa is one of the most radioresistant tissues in the body* - The **GI mucosa** is one of the **most radiosensitive** tissues due to its rapid cell turnover and high proliferative capacity, leading to symptoms like mucositis and diarrhea after radiation. - The constant renewal of epithelial cells makes them highly vulnerable to the **cytotoxic effects** of radiation. *Rapidly dividing cells are resistant to radiation* - **Rapidly dividing cells**, such as those in the bone marrow, GI crypts, and hair follicles, are generally **most sensitive** to radiation. - This forms the basis of radiation therapy, as cancer cells often have a higher proliferative rate than many normal tissues, making them a target. *The intensity of radiation is inversely proportional to the square of distance from the source* - This statement describes the **inverse square law** for radiation intensity, which is true, but it is a principle of radiation physics, not a statement about the radiosensitivity of tissues. - The inverse square law dictates how radiation dose **attenuates with distance**, which is critical for dose calculation but not directly about biological radiosensitivity.

Question 1

The Figure of 3 sign on chest X-ray is seen in which condition?

Accepted Answer

Coarctation of the Aorta

Answer

Transposition of the Great Arteries

Answer

Mitral Stenosis

Answer

Aortic Stenosis

Question 2

Radiation Dose Monitoring in Occupational Workers is done by

Accepted Answer

TLD Badge

Answer

Collimators

Answer

Grid

Answer

Linear Accelerator

Question 3

Which of the following is a FALSE statement regarding radiation?

Accepted Answer

Small blood vessels are relatively resistant to radiation compared to other tissues

Answer

GI mucosa is one of the most radiosensitive tissues in the body

Answer

Rapidly dividing cells are highly sensitive to Radiation

Answer

The intensity of Radiation is inversely proportional to the square of distance from the source

Question 4

Which radiotherapy technique involves the use of remote afterloading to deliver radiation directly to the tumor?

Accepted Answer

Brachytherapy

Answer

External Beam Radiotherapy

Answer

Stereotactic Radiotherapy

Answer

Proton Beam Radiotherapy

Question 5

A 7-week pregnant lady underwent a chest X-ray by mistake. What is to be done?

Accepted Answer

Reassure the patient and continue the pregnancy.

Answer

Terminate the pregnancy immediately due to radiation exposure.

Answer

Perform chromosomal testing to assess fetal damage.

Answer

Conduct prenatal invasive diagnostic tests to evaluate fetal health.

Question 6

A 55 year old woman diagnosed with ca cervix stage IIb is advised for chemoradiation. Which of the following is the true statement regarding radiation use?

Accepted Answer

Dose/Intensity of radiation is inversely proportional to the square of distance of source

Answer

Rapidly proliferating cells are less affected by radiation

Answer

The small bowel is not significantly affected by radiation

Answer

Small blood vessels are unaffected by radiation

Question 7

Cancer patient undergoes radiotherapy, pick the true statement for radiosensitivity of tissues?

Accepted Answer

Small blood vessels are radiosensitive tissues

Answer

GI mucosa is one of the most radioresistant tissues in the body

Answer

Rapidly dividing cells are resistant to radiation

Answer

The intensity of radiation is inversely proportional to the square of distance from the source

NEET-PG 2020 — Radiology