Source-Iris Distance

The distance between the radiation source and the diaphragm is one of the key parameters in radiotherapy. This distance determines the shape and size of the radiation beam that will be used to treat the patient. In this article, we will look at what the Source-Diaphragm Distance (IDR) is, how it affects treatment, and what methods are used to measure it.

The IDR distance is the distance from the radiation source in a radiation therapy machine to the external surfaces of protective elements, such as a tube, collimator or diaphragm, that form the radiation beam. This distance is measured in centimeters and may vary for each type of device and treatment method.

When treating cancer and other diseases with radiation therapy, the shape and size of the radiation beam play an important role. If the beam is too narrow, it may not reach all parts of the tumor and may not destroy it completely. If the beam is too wide, it can damage healthy tissue around the tumor and cause side effects in the patient.

Thus, the IDR distance influences the shape and size of the radiation beam and therefore the effectiveness of the treatment. The greater the IDR distance, the wider the radiation beam and the greater the likelihood of damaging healthy tissue. Therefore, when choosing the IDR distance, tumor size, location, and other factors must be taken into account to ensure maximum treatment effectiveness and minimize side effects.

Special tools and techniques are used to measure IDR distance. For example, some radiation therapy machines have built-in sensors that can automatically measure the IDR distance and adjust it if necessary. There are also special tools for measuring IDR distance manually, such as rulers and templates.

In general, the IDR distance is an important parameter in radiotherapy treatment and requires careful monitoring and measurement.

**Source-diaphragm distance** **-** distance from the radiation source to the external elements of the device. A protective element is located here - the diaphragm. It is a flat piece with a round hole. The diaphragm can be used to change the size of the beam, concentrating it.

The distance from the isocenter to the aperture is the main parameter