Quality assurance of 3D-CRT: indications and difficulties in their applications.

Although more advanced techniques such as intensity-modulated radiotherapy are rapidly spreading, 3D conformal radiotherapy (3D-CRT) remains the standard of treatment for many diseases. The authors outline essential indications to guarantee the quality of 3D-CRT treatments. Criteria for clinical indications and potential clinical advantages and disadvantages of 3D-CRT technology are presented. After briefly listing human and technological resources requirements, procedures for 3D-CRT and physical aspects peculiar to 3D-CRT are described. Medical physics support activities are also considered, including suggestions concerning quality control protocols. Difficulties in the application of correct quality procedures, particularly related to human and technological resources, procedures for patient positioning, imaging, contouring, treatment planning, in vivo dosimetry, set-up verification, follow-up, dose delivery are then discussed.