Comparison of PET/CT with CT alone for target volume definition in radiation treatment in patients with lung cancer

METHODS

Twenty-five patients with small cell lung (SCL) or non-small
cell lung (NSCL) cancer were studied. CT and PET images
were obtained in treatment position. GTV and CTV were defined
first using the CT alone and then using the registered
CT and PET. For each patient, two 3D-conformal radiotherapy
(CRT) plans were made and they were compared with respect
to the GTV, CTV, mean lung dose (MLD) and V_lung20Gy.

RESULTS

PET changed GTV in 17 patients. PET increased CTV in 7
patients. In 16 patients with atelectasis, decrease in CTV led
to reduced dose to the lung. CTV enlarged and values of MLD
and V_lung20Gy increased in 5 patients with PET findings.

CONCLUSION

The use of PET/CT in radiotherapy is helpful in defining the
tumor more precisely and possibly sparing more normal lung
tissues. It is also helpful in differentiating tumor from atelectatic
lung.

Keywords: Lung cancer; image fusion; target definition; PET/CT; radiation therapy; treatment planning