NEET-PG 2015 - Radiology PYQs Practice Questions

Q: What is the cardiothoracic ratio in children?

50-55%. ***50-55%*** - The normal **cardiothoracic ratio** in children is generally considered to be **50-55%** on a **posterior-anterior (PA) chest X-ray**. - In **infants and young children (under 2 years)**, the ratio can be **up to 55-60%** due to relatively larger cardiac size and more horizontal positioning of the heart. - In **older children (over 2 years)**, the normal ratio approaches adult values of **less than 50%**. - A ratio consistently greater than 55% could indicate **cardiomegaly**, which warrants further investigation. *30-35%* - This range is typically too low and would suggest an **unusually small heart** for the chest cavity, which is not a normal finding in children. - A very low ratio like this is not characteristic of the pediatric population and may indicate technical issues with the radiograph. *40-45%* - While this range approaches normal values for **older children and adults**, it is generally on the lower side for the average **pediatric cardiothoracic ratio**. - This percentage alone is not the best answer when considering the entire pediatric age spectrum, including infants and younger children. *60-65%* - A cardiothoracic ratio in this range would typically be considered **abnormal** and indicative of **cardiomegaly** in children beyond infancy. - Such an elevated ratio would suggest an enlarged heart, prompting further cardiac evaluation including **echocardiography** to assess for structural heart disease. [Practice more Radiology PYQs on OnCourse]

Q: Which of the following imaging modalities is most appropriate for initial evaluation of suspected acute appendicitis in a young adult patient?

Ultrasound. ***Ultrasound*** - **First-line imaging modality** for suspected acute appendicitis in young adults, especially in children, pregnant women, and young females - **Advantages:** No ionizing radiation, readily available, cost-effective, can be performed at bedside - **High specificity** (>90%) when positive findings are present - **Graded compression technique** helps visualize the appendix and assess for periappendiceal inflammation - **Limitations:** Operator-dependent, may be difficult in obese patients or with overlying bowel gas *CT scan (Contrast-enhanced)* - **Most sensitive imaging modality** (sensitivity >95%) for acute appendicitis - Considered when ultrasound is inconclusive or technically difficult - **Gold standard** in adults, especially in obese patients - Provides excellent visualization of the appendix and complications (perforation, abscess) - However, involves **ionizing radiation**, making it less ideal as first-line in young patients *MRI* - **Preferred in pregnant women** when ultrasound is inconclusive - No ionizing radiation exposure - High accuracy but **limited availability**, longer scan time, and higher cost - Not typically used as first-line imaging in non-pregnant young adults *Plain radiography (X-ray)* - **Limited role** in diagnosing acute appendicitis - Non-specific findings; may show fecalith, loss of psoas shadow, or signs of perforation - Cannot reliably visualize the appendix - **Not recommended** as initial imaging for suspected appendicitis [Practice more Radiology PYQs on OnCourse]

Q: What is the best investigation for diagnosis and staging of renal cell carcinoma with thrombus extending into the IVC?

CT scan. ***CT scan*** - **CT scan** with contrast is the gold standard for diagnosing renal cell carcinoma and evaluating the extent of tumor thrombus into the **IVC**. - It provides detailed anatomical information on the tumor, staging, and involvement of adjacent structures. *Angiography* - **Angiography** is an invasive procedure primarily used for mapping the vascular supply of the tumor preoperatively or for embolization, not as a primary diagnostic tool. - It carries risks associated with contrast agents and catheterization and provides less comprehensive detail on tumor extension compared to CT. *Colour doppler imaging* - While useful for detecting blood flow and confirming the presence of a thrombus, **color Doppler imaging** (ultrasound) has limitations in accurately assessing the cranial extent of an IVC thrombus. - Its diagnostic accuracy is highly operator-dependent and less reliable for deep structures like the IVC compared to CT. *IVP* - **Intravenous Pyelogram (IVP)** assesses the urinary tract's structure and function but has limited utility in detecting soft tissue masses like renal cell carcinoma or IVC thrombus. - It involves radiation exposure and contrast material, and has largely been replaced by more advanced imaging techniques like CT and MRI for renal masses. [Practice more Radiology PYQs on OnCourse]

Q: Precisely directed high dose radiation is used in which of the following therapies?

Stereotactic radiosurgery. ***Stereotactic radiosurgery*** - **Stereotactic radiosurgery (SRS)** is a highly precise radiation therapy that uses focused, high-dose radiation beams to target small tumors or abnormalities with **sub-millimeter accuracy**. - It delivers **very high doses per fraction** (typically 15-24 Gy in a single session) using stereotactic guidance systems. - Commonly used for **brain metastases, AVMs, acoustic neuromas**, and other small intracranial targets. *IMRT* - **Intensity-modulated radiation therapy (IMRT)** is an advanced form of 3D-conformal radiation therapy that modulates beam intensity to conform to tumor shape. - While IMRT is precise, it uses **conventional fractionation** (1.8-2 Gy per fraction over many treatments), not the high-dose approach of SRS. *EBRT* - **External beam radiation therapy (EBRT)** is a general term for radiation delivered from outside the body. - It encompasses various techniques but *does not specifically indicate the **stereotactic precision and high-dose per fraction** characteristic of SRS*. *Brachytherapy* - **Brachytherapy** involves placing radioactive sources **directly inside or next to the tumor**. - While it delivers high doses locally, it is not "precisely directed high-dose radiation" from external beams like SRS. [Practice more Radiology PYQs on OnCourse]

Q: All are done to minimize radiation exposure to the patient under fluoroscopy, except which of the following?

Increasing fluoroscopic time. ***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. [Practice more Radiology PYQs on OnCourse]

Question 1

What is the cardiothoracic ratio in children?

Accepted Answer

50-55%

Answer

30-35%

Answer

40-45%

Answer

60-65%

Question 2

Which of the following imaging modalities is most appropriate for initial evaluation of suspected acute appendicitis in a young adult patient?

Accepted Answer

Ultrasound

Answer

CT scan (Contrast-enhanced)

Answer

Plain radiography (X-ray)

Answer

MRI

Question 3

What is the best investigation for diagnosis and staging of renal cell carcinoma with thrombus extending into the IVC?

Accepted Answer

CT scan

Answer

Angiography

Answer

Colour doppler imaging

Answer

IVP

Question 4

Precisely directed high dose radiation is used in which of the following therapies?

Accepted Answer

Stereotactic radiosurgery

Answer

EBRT

Answer

IMRT

Answer

Brachytherapy

Question 5

All are done to minimize radiation exposure to the patient under fluoroscopy, except which of the following?

Accepted Answer

Increasing fluoroscopic time

Answer

Decreasing fluoroscopic time

Answer

Using low dose of radiation

Answer

Decrease in field of view

Question 6

Substance used for PET scan is

Accepted Answer

18F-FDG

Answer

Gadolinium

Answer

Gastrografin

Answer

Iodine

Question 7

In which of the following cancers is intraoperative radiotherapy (IORT) applicable?

Accepted Answer

All of the options

Answer

Gastric cancer

Answer

Colon carcinoma

Answer

Pancreatic carcinoma

Question 8

Which of the following is not considered a contraindication for undergoing an MRI?

Accepted Answer

Ryle's tube

Answer

Cardiac pacemaker

Answer

Cochlear implant

Answer

Metallic splinter in eye

Question 9

Rigler's sign is suggestive of?

Accepted Answer

Pneumoperitoneum

Answer

Pneumothorax

Answer

Peritonitis

Answer

Hemothorax

Question 10

Which condition is characterized by a specific appearance on CT scans that resembles small centrilobular nodules with branching linear structures?

Accepted Answer

Pulmonary tuberculosis

Answer

Silicosis

Answer

Pulmonary hydatid cyst

Answer

Small cell carcinoma

NEET-PG 2015 — Radiology