The dose to air is found to be 1.2 Gy. What is the exposure?

The point of maximum dose is referred to as:

100 rads = 100 cGy.  

If the percent depth dose at a depth of 5 cm using a 6 MV beam (Dmax = 1.5 cm) at an SSD of 100 cm is 77.5%, what is the percent depth dose at the same depth if the SSD is extended to 110 cm?

The point of maximum dose for megavoltage beams is at the skin surface.

Absorbed dose is maximum at the surface. 

Field size may be defined geometrically or dosimetrically; geometric field size typically corresponds to the field as defined by the field light while the dosimetric field size corresponds to the 50% isodose line. 

Backscatter factor is affected by all of the following except:

Kerma stands for the kinetic energy released in a medium. 

The Mayneord F factor is used for dose calculation when the treatment SSD is different from the standard SSD.