In a PA projection of the chest for cardiac evaluation, the heart measures 15.2 cm. If the magnification factor is 1.3, what is the actual diameter of the heart?

To determine the actual diameter of the heart from the PA projection measurement, you need to account for the magnification factor. The measured size of the heart on the image is influenced by how much it is enlarged or reduced due to the imaging technique.

When you have a magnification factor, the actual size can be calculated by dividing the measured size of the heart by the magnification factor. In this case, the measured heart size is 15.2 cm and the magnification factor is 1.3.

So, to find the actual diameter, you use the formula:

[

\text{Actual Diameter} = \frac{\text{Measured Diameter}}{\text{Magnification Factor}}

]

Substituting in the known values:

[

\text{Actual Diameter} = \frac{15.2 \text{ cm}}{1.3} \approx 11.7 \text{ cm}

]

This calculation accurately reflects the relationship between the measured diameter and the magnification factor, allowing for an accurate estimation of the actual size of the heart. Hence, the correct answer is 11.7 cm.