On the delineation of the gross tumor volume and clinical target volume for head and neck squamous cell carcinomas

Gross tumor volume (GTV) and clinical target volume (CTV) delineation on pl anning computed tomography (pICT) for head and neck squamous cell carcinoma s can be troublesome. We highlight the factors which can be crucial for the radiation oncologist in delineating GTV and CTV on pICT and provide some p ratical solutions. Regarding GTV, uncertainties are correlated with transfe r of information collected by physical examination and diagnostic radiology to pICT. Moreover, reproducibility of delineation can also be highly varia ble, particularly when diagnostic imaging quality and pICT quality are poor . Once the prescription has been made, clinical target volume identificatio n on pICT is rarely straightforward. Whereas there are some data about the location of major lymph node stations of the neck, there are no reported gu idelines on how to draw subclinical extention of primary head and neck tumo rs on pICT, Such volumes can be derived from those currently included in si mulator films or from those addressed by the surgeon. Some examples are pro vided. A particular situation is represented by the adjuvant setting, when the primary tumor is removed (by surgery) or reduced (by chemotherapy), In conclusion, this paper shows some major problems associated with identifica tion of GTV and CTV on pICT, Apart from selected cases, the use of pICT for target volume delineation (and thus for field shaping) for head and neck s quamous cell carcinoma Is still to be considered investigational.