The usability of phantoms plays a critical role in commissioning and quality assurance programs in radiotherapy departments as they improve patient care setup with greater precision between personalized treatment planning and irradiation setup uncertainties. With the emergence of these new radiotherapy modalities, it became necessary to apply relatively small fields that are dynamic or static. The use of these field sizes can cause uncertainty in dosimetry, requiring special attention in small field dosimetry. TLDs have advantages for having characteristics such as high spatial resolution and dose response, offering a promising opportunity to measure the absorbed dose in a small field. As a result, we can conclude that the use of the 3D phantom with thermoluminescent dosimeters proved to be very useful in the application of small field dosimetry, enabling a more accurate investigation in quality controls involving treatments whose doses are relatively high in radiosurgery techniques that require more accurate and reliable measurements in dose delivery.