Which factors does Tissue Maximum Ratio (TMR) depend on?

Tissue Maximum Ratio (TMR) is an important concept in radiation therapy that provides information about the dose distribution of a radiation beam as it penetrates different depths of tissue. TMR is influenced by several key factors.

Depth is a critical variable because the amount of tissue that the radiation beam passes through increases with depth, leading to changes in the beam's intensity due to attenuation. At greater depths, there is a higher likelihood for the radiation to lose energy, which impacts the maximum dose delivered to the tissue.

Field size also plays a significant role in TMR. A larger field size can increase the amount of scatter radiation and the dose delivered to the tissue, affecting the TMR values. This relationship means that TMR values can vary based on the size of the radiation treatment area.

Beam quality, which refers to the energy of the radiation beam, is another factor that affects TMR. Higher energy beams have greater penetrating power, resulting in different TMR levels compared to lower energy beams. This variation influences the dose distribution within the tissue as well.

Given these dependencies, TMR is indeed influenced by depth, field size, and beam quality, making "all of the above" the most comprehensive and accurate choice. Understanding these relationships is crucial for medical