Source-Surface Distance

The source-surface distance is the distance from the source of ionizing radiation in the radiation therapy apparatus to the nearest surface of the irradiated object (patient, phantom).

This distance is an important parameter when conducting radiation therapy. It affects the radiation dose on the surface and in the depth of the irradiated object. The greater the source-surface distance, the lower the dose at the surface due to scattering of radiation in the air.

When setting irradiation parameters, this distance must be taken into account in order to obtain the required dose distribution over depth. Typically, the source-surface distance in radiation therapy machines ranges from 50 to 150 cm.

The source-surface distance is the distance between the source of ionizing rays in a radiation therapy machine and the surface of the irradiated area (patient or phantom), which must be at a certain distance from it to ensure the necessary radiation exposure to the affected area. This distance plays an important role in the radiation therapy process, as it determines the level of radiation dose the patient will receive with each treatment session and the appropriate protection of surrounding tissue.

When using radiation therapy machines, the correct source-to-surface distance must be established, which will depend on the type and power of the equipment, as well as the individual characteristics of the patient (for example, the thickness of the affected area). In many cases, special indicators or sensors are used that allow you to automatically determine the distance and adjust the device parameters accordingly. In addition, it is important to ensure that the patient and staff are kept a safe distance from the radiation source to avoid possible health damage caused by X-rays.

Correctly determining the source-surface distance can be a difficult process, especially for novice users. But with professional training and experience, it becomes much clearer. Therefore, regular consultation with specialists such as radiologists is an important aspect of providing safe and effective radiotherapy.