If multiple tenth-value layers are installed the calculated dose may be lower than actual dose rate. This is due to:

If multiple tenth-value layers are installed the calculated dose may be lower than actual dose rate. This is due to:

• A. Build up Factor
• B. Compton Scatter photons generated within shielding
• C. Attenuation
• D. Distance

Answer: (A)

Shielding calculations using tenth-value layers assume only the primary photons are attenuated. In reality, photons scatter inside the shielding material and generate secondary photons that can still reach the point of interest. The buildup factor quantifies this extra contribution from internally produced photons. As you add more shielding thickness (multiple TVLs), the opportunities for internal scattering increase, so the actual dose rate can be higher than what a simple attenuation calculation predicts. This is why the measured dose may be higher than the calculated dose when buildup is not included.

Shielding calculations using tenth-value layers assume only the primary photons are attenuated. In reality, photons scatter inside the shielding material and generate secondary photons that can still reach the point of interest. The buildup factor quantifies this extra contribution from internally produced photons. As you add more shielding thickness (multiple TVLs), the opportunities for internal scattering increase, so the actual dose rate can be higher than what a simple attenuation calculation predicts. This is why the measured dose may be higher than the calculated dose when buildup is not included.