The standard chest X-ray (PA) view is obtained at a fixed distance between the X-ray tube and the cassette of:

The correct answer is: 2) 180 cm

Explanation:

In radiology, the posterior-anterior (PA) chest X-ray is commonly performed with the X-ray tube positioned 180 cm from the film or digital cassette. This distance helps provide clear, high-quality images of the chest, minimizing the distortion of structures like the heart and lungs.

• 180 cm is the standard distance used for the PA view in chest radiography. This distance allows for accurate imaging of the lungs, heart, and other structures in the chest without excessive magnification, particularly of the heart.

Explanation of Other Options:

• 240 cm: This distance is sometimes used in certain specialized radiographic techniques, but it is not the standard distance for a PA chest X-ray.

• 100 cm: A distance of 100 cm is commonly used for other types of radiographs but is too short for a standard chest X-ray, as it can cause magnification of heart structures.

• 60 cm: This is even shorter and typically used for specific techniques like lateral or close-up radiographs, not for standard chest X-rays.

Conclusion: The standard PA chest X-ray is obtained with a distance of 180 cm between the X-ray tube and the cassette, ensuring optimal image quality for clinical evaluation.