What Is Adaptive Radiotherapy?

Adaptive Radiotherapy is the modification of the radiotherapy plan administered to the patient during Radiotherapy to account for changes in patient anatomy (such as tumor shrinkage or growth, weight loss, and organ movement) and tumor biology (such as hypoxia).

Adaptive Radiotherapy aims to measure the changes in the treatment process and to make the dose distribution equal to the planned optimal dose distribution with the readjustment of the plan. Treatment with Adaptive Radiotherapy has become personalized. Adaptive Radiotherapy administration takes three steps: image guidance, treatment adaptation, and dose verification.

Adaptive Radiotherapy is an old concept, but technical limitations have prevented it from entering routine practice. ART ensures that the dose of Radiotherapy can be given precisely and accurately, thus increasing the effectiveness of Radiotherapy. The need for a new plan arises in cases where the delivered dose falls below the accepted value of the target volume wrap and the organs at risk receive an amount above the tolerance dose. Clinical results of adaptive Radiotherapy have just begun to be published. As a result of the data obtained from the studies conducted to date, many factors, such as weight loss, number of fractions, or changes in body contour, could affect the timing of the adaptive plan.

Why is Adaptive Radiotherapy Necessary?

  • External Radiotherapy (EXRT) is the most commonly used technique in cancer radiotherapy.
  • It is assumed that the daily anatomy remains constant and does not change during treatment, and therefore
  • Generally, in EXRT, the treatment plan is made once, and the same method is used throughout the entire treatment.
  • This assumption is only sometimes valid due to daily variations in anatomy, target shape, and position.
  • During the treatment period
  • Shape and position of the target – tumor shrinkage or growth
  • Anatomical – changes in the fullness of organs with a cavity or cavity, organ movement, weight loss
  • Changes in tumor biology (such as hypoxia)

Adaptive Radiotherapy in Lung Cancer

In the treatment process of lung cancers, internal organ movement, reduction in tumor volume, change in respiratory pattern, and weight loss are observed. This causes a shift in dosimetry. In the study of Vlachaki et al., a decrease from 35% to 26% was found in the volume of the lung receiving 20 Gy with Adaptive Radiotherapy. The average doses received by the lungs, heart, and esophagus were less. As a result, it can be said that treating lung cancer can reduce side effects in critical structures with ART, and increasing the dose can increase tumor control.

 Adaptive Radiotherapy in Liver Tumors

Liver tumors are also a group that may benefit from ART due to respiratory-related organ movement and the low radiation tolerance of the liver. Planning and implementation strategies such as the ‘internal target volume’ (ITV) approach and patient-specific respiratory width detection are used. The dosimetric difference in normal tissues indicated that increasing the dose with ART is possible.