P3-170: The necessity of a correct dose calculation algorithm for stereotactic lung irradiation

Abstract

tion of dose distributions in lung tumours have been used to correct DVH's planned in a static situation with pencil beam to a dynamic situation, considering breathing motions and a more correct dose calculation. Results: At 17 mo. after end of study there is one local relapse alone and 7 cases displaying distant metastasis of which 2 are combined with regional failure (1 T1 and 6 T2). Grade 3 toxicity was seen in 3 patients with dyspnoe at 3, 6 and 9 months, not correlated with pneumonitis or fibrosis. Spirometry data will be reported. Grade 3 toxicity with pain in the thorax was seen in 2 patients at 9 and 12 months not associated with rib fracture or tumor in proximity to the thoracic wall. 13/59 (22%) did not have any side effects. The most common side effect at 6 weeks was grade I skin reactions (19 patients with grade I and 4 with grade 2). At 17 mo. after end of study 11 pts. had obtained CR, 30 showed PR and 8 pats. had either local failure and/or distant metastases. Conclusion: Using 15 x 3 Gy to stage I NSCLC results in acceptable early toxicity and favourable local control rate non inferior to what has been reported with fractionated RT.

Frameless Stereotactic Body Radiotherapy for Lung Cancer Using Four-Dimensional Cone Beam CT Guidance

“…A dose of 3 Â 18 Gy was prescribed on the isodose surface that encompassed 95% of the PTV. This dose prescription is on average equivalent to the 3 Â 20 Gy of the RTOG 0236 protocol planned without heterogeneity correction (14).…”