Superior sulcus non-small cell lung carcinoma: A comparison of IMRT and 3D-RT dosimetry

Abstract

Aim

A dosimetric study comparing intensity modulated radiotherapy (IMRT) by TomoTherapy to conformational 3D radiotherapy (3D-RT) in patients with superior sulcus non-small cell lung cancer (NSCLC).

Background

IMRT became the main technique in modern radiotherapy. However it was not currently used for lung cancers. Because of the need to increase the dose to control lung cancers but because of the critical organs surrounding the tumors, the gains obtainable with IMRT is not still demonstrated.

Material and methods

A dosimetric comparison of the planned target and organs at risk parameters between IMRT and 3D-RT in eight patients who received preoperative or curative intent irradiation.

Results

In the patients who received at least 66[[ce:hsp sp="0.25"/]]Gy, the mean V95% was significantly better with IMRT than 3D-RT (p[[ce:hsp sp="0.25"/]]=[[ce:hsp sp="0.25"/]]0.043). IMRT delivered a lower D2% compared to 3D-RT (p[[ce:hsp sp="0.25"/]]=[[ce:hsp sp="0.25"/]]0.043). The IH was significantly better with IMRT (p[[ce:hsp sp="0.25"/]]=[[ce:hsp sp="0.25"/]]0.043). The lung V_{5[[ce:hsp sp="0.25"/]]Gy} and V_{13[[ce:hsp sp="0.25"/]]Gy} were significantly higher in IMRT than 3D-RT (p[[ce:hsp sp="0.25"/]]=[[ce:hsp sp="0.25"/]]0.043), while the maximal dose (D_max) to the spinal cord was significantly lower in IMRT (p[[ce:hsp sp="0.25"/]]=[[ce:hsp sp="0.25"/]]0.043). The brachial plexus D_max was significantly lower in IMRT than 3D-RT (p[[ce:hsp sp="0.25"/]]=[[ce:hsp sp="0.25"/]]0.048). For patients treated with 46[[ce:hsp sp="0.25"/]]Gy, no significant differences were found.

Conclusion

Our study showed that IMRT is relevant for SS-NSCLC. In patients treated with a curative dose, it led to a reduction of the exposure of critical organs, allowing a better dose distribution in the tumor. For the patients treated with a preoperative schedule, our results provide a basis for future controlled trials to improve the histological complete response by increasing the radiation dose.