In image guided radiotherapy (IGRT), cone beam computed tomography (CBCT) is an important tool for patient positioning and verification before treatment. Therefore, the CBCT system has become an essential part and significant component of radiation therapy because it is a development that facilitates more accurate delivery of the prescribed dose to the treatment sites. However, the CBCT system uses ionizing radiation to acquire images for patient setup. Historically, the significance of this imaging dose has been overlooked as it is relatively small in quantity when compared to therapeutic doses used to patients for treatment purposes. In recent years, several works have been made to estimate the dose delivered from CBCT imaging using Monte Carlo simulations in phantoms and patients, thermoluminescence dosimetry (TLD) as well as a variety of other dosimetry methods. The aim of this chapter is to summarize the results from international literature concerning the additional imaging dose delivered to patients due to the usage of Cone Beam CT during radiation therapy, as well as to discuss the future work necessary in order to arrive at a clinically relevant personalized dose estimation protocol.

We performed electronic research for articles published in PubMed, MEDLINE, and ScienceDirect databases from January 2004 to January 2023. The systematic review of twenty (20) peer-reviewed articles about dosimetric parameters and eight (8) articles about clinical outcomes confirmed the dosimetric advantages of ART through better target coverage and Organs at Risk (OARs) sparing, with subsequent benefits on decreased toxicity and improved clinical outcome, specifically local control of the disease. ART replanning is a sustainable strategy for minimizing toxicity by improving normal tissue sparing. Furthermore, it enhances target volume coverage by correctly determining the specific amount of dose to be delivered to the tumor. In conclusion, this review confirms that ART benefits dosimetric, clinical/therapeutic, and toxicity outcomes.