What Is External Beam Radiation Therapy?

The radiation emitted by a radiation source passes through a certain fixed space outside the body and passes through the normal tissues of the human body and adjacent organs to a certain diseased part of the human body. Generally divided into fixed-source skin-pitch treatment technology, isocenter treatment technology and rotary irradiation technology.

Chinese name

External irradiation treatment

Foreign name

externalradiation therapy

Overview of external radiation treatment

The radiation emitted by a radiation source passes through a certain fixed space outside the body and passes through the normal tissues of the human body and adjacent organs to a certain diseased part of the human body. Generally divided into fixed-source skin-pitch treatment technology, isocenter treatment technology and rotary irradiation technology.

SSD External source treatment with fixed source skin distance (SSD) irradiation technology

(1) Principle:

1. The distance from the radiation source (S) to the skin is fixed

2. The treatment machine and other centers (A) are placed on the patient's skin;

3. The center of the tumor or target area (T) is placed on the line connecting the two points of the radiation source and the skin incident point.

(2) Advantages: Simple positioning.

(3) Disadvantages: The rack angle must be accurate, and the patient's position must be accurate, otherwise the tumor center will easily escape the center of the field or the field.

SAD External Centered Angle (SAD) Irradiation

(1) Principle

The center of the tumor or target area (T) is placed at the isocenter of the treatment machine. The distance from the source to the tumor is fixed and equal to the radius of rotation of the machine.

(2) Advantages: As long as the isocenter is on the center of the tumor or target area, the accuracy of the angle of the treatment machine or the error of the patient's position can ensure that the central axis of the shooting field passes through the center of the tumor or target area. Easy to set up.

(3) Disadvantage: Accurate positioning of the bed is required.

ROT Rotation (ROT) irradiation technology

(1) Principle

Taking the center of the tumor or target area as the rotation center, the rotating angle of the frame is used instead of the fixed angle irradiation of the SAD technology.

(2) Advantages: Same as SAD technology.

(3) Disadvantages: Same as SAD technology.