The cassette comprises a copper step wedge, an intensifying screen, and a light absorber. The copper step wedge provides a specific penetration value, while the intensifying screen, which is not shielded by the step wedge, allows light to pass through the light absorber before reaching the film. This process reduces the exposure. The penetration through the light absorber remains constant and is unaffected by the Kv.P. This particular area on the film represents a reference density that corresponds to a known penetration value. The components within the cassette are designed to measure x-ray penetration and aid in determining Kv.P.