Final answer:
The term used to describe the total energy absorbed by a patient from a radiation beam is the "absorbed dose," specifically measured in grays (Gy) in the International System of Units (SI).
Step-by-step explanation:
The term used to describe the total energy absorbed from the beam by the patient is the "absorbed dose." The absorbed dose is a measurement of energy deposited by ionizing radiation in a unit mass of tissue. The International System of Units (SI) measure for absorbed dose is the gray (Gy), defined as the absorption of one joule of radiation energy per kilogram of matter (J/kg). In terms of the options provided, the answer is 1. integral dose, as it represents the total energy absorbed by all of the irradiated tissues within the patient.
When discussing the absorbed dose, it's important to differentiate it from other units such as the roentgen, which measures the energy absorbed by dry air, and the sievert (Sv), which is used to measure the effective dose that accounts for the type of radiation and its impact on different types of tissues. The joule is a unit of energy, but it is not used specifically to describe the absorption of energy from radiation in the context of a patient.