Bone matching versus tumor matching in image-guided carbon ion radiotherapy for locally advanced non-small cell lung cancer.

Background and purpose: This study evaluates the dosimetric impact of tumor matching (TM) and bone matching (BM) in carbon ion radiotherapy for locally advanced non-small cell lung cancer.

Materials and methods: Forty patients diagnosed with locally advanced non-small cell lung cancer were included in this study. TM and BM techniques were employed for recalculation based on re-evaluation computed tomography (CT) images of the patients, resulting in the generation of dose distributions: Plan-T and Plan-B, respectively. These distributions were compared with the original dose distribution, Plan-O. The percentage of the internal gross tumor volume (iGTV) receiving a prescription dose greater than 95% (V95%) was evaluated using dose-volume parameters. Statistical analysis was performed using a paired signed-rank sum test. Additionally, the study investigated the influence of tumor displacement, volume changes, and rotational errors on target dose coverage.

Results: The median iGTV V95% values for the Plan-O, Plan-T, and Plan-B groups were 100%, 99.93%, and 99.60%, respectively, with statistically significant differences observed. TM demonstrated improved target dose coverage compared to BM. Moreover, TM exhibited better target coverage in case of larger tumor displacement. TM's increased adjustability in rotation directions compared to BM significantly influenced dosimetric outcomes, rendering it more tolerant to variations in tumor morphology.

Conclusion: TM exhibited superior target dose coverage compared to BM, particularly in cases of larger tumor displacement. TM also demonstrated better tolerance to variations in tumor morphology.