A treatment planning comparison between modulated tri-cobalt-60 teletherapy and linear accelerator based stereotactic body radiotherapy for central early-stage non small cell lung cancer

作者：Merna Catherine; Rwigema Jean Claude M; Cao Minsong; Wang Pin Chieh; Kishan Amar U; Michailian Argin; Lamb James; Sheng Ke; Agazaryan Nzhde; Low Daniel A; Kupelian Patrick; Steinberg Michael L; Lee Percy^*

来源：Medical Dosimetry, 2016, 41(1): 87-91.

DOI：10.1016/j.meddos.2015.09.002

• Early-stage lung cancer
• non-small cell lung cancer
• SBRT
• MRI-guided radiotherapy
• ViewRay

We evaluated the feasibility of planning stereotactic body radiotherapy (SBRT) for large central early stage non-small cell lung cancer with a tri-cobalt-60 (tri-Co-60) system equipped with real-time magnetic resonance imaging (MRI) guidance, as compared to linear accelerator (LINAC)-based SBRT. In all, 20 patients with large central early-stage non-small cell lung cancer who were treated between 2010 and 2015 with LINAC-based SBRT were replanned using a tri-Co-60 system for a prescription dose of 50 Gy in 4 fractions. Doses to organs at risk were evaluated based on established MD Anderson constraints for central lung SBRT. R-100 values were calculated as the total tissue volume receiving 100% of the dose (V-100) divided by the planning target volume and compared to assess dose conformity. Dosimetric comparisons between LINAC-based and tri-Co-60 SBRT plans were performed using Student's t-test and Wilcoxon Ranks test. Blinded reviews by radiation oncologists were performed to assess the suitability of both plans for clinical delivery. The mean planning target volume was 48.3 cc (range: 12.1 to 139.4 cc). Of the tri-Co-60 SBRT plans, a mean 97.4% of dosimetric parameters per patient met MD Anderson dose constraints, whereas a mean 98.8% of dosimetric parameters per patient were met with LINAC-based SBRT planning (p = 0.056). R100 values were similar between both plans (1.20 vs 1.21, p = 0.79). Upon blinded review by 4 radiation oncologists, an average of 90% of the tri-Co-60 SBRT plans were considered acceptable for clinical delivery compared with 100% of the corresponding LINAC-based SBRT plans (p = 0.17). SBRT planning using the tri-Co-60 system with built-in MRI is feasible and achieves clinically acceptable plans for most central lung patients, with similar target dose conformity and organ at risk dosimetry. The added benefit of real-time MRI-guided therapy may further optimize tumor targeting while improving normal tissue sparing, which warrants further investigation in a prospective feasibility clinical trial.

• 出版日期2016
• 单位UCLA