Abstract
Homogeneous target dose distribution in intensity-modulated radiotherapy (IMRT) for sinonasal cancer (SNC) is challenging to achieve. To solve this problem, we established and evaluated a basal-dose-compensation (BDC) optimization approach, in which the treatment plan is further optimized based on the initial plans. Generally acceptable initial IMRT plans for thirteen patients were created and further optimized individually by (1) the BDC approach and (2) a local-dose-control (LDC) approach, in which the initial plan is further optimized by addressing hot and cold spots. We compared the plan qualities, total planning time and monitor units (MUs) among the initial, BDC, LDC IMRT plans and volumetric modulated arc therapy (VMAT) plans. The BDC approach provided significantly superior dose homogeneity/conformity by 23%–48%/6%–9% compared with both the initial and LDC IMRT plans, as well as reduced doses to the organs at risk (OARs) by up to 18%, with acceptable MU numbers. Compared with VMAT, BDC IMRT yielded superior homogeneity, inferior conformity and comparable overall OAR sparing. The planning of BDC, LDC IMRT and VMAT required 30, 59 and 58 minutes on average, respectively. Our results indicated that the BDC optimization approach can achieve significantly better dose distributions with shorter planning time in the IMRT for SNC.
Highlights
Tumor site nasal cavity nasal cavity nasal cavity nasal cavity maxillary sinus nasal cavity nasal cavity maxillary sinus nasal cavity nasal cavity ethmoid sinus maxillary sinus nasal cavity
We proposed an optimization approach referred to as basal dose compensation (BDC), in which an initial intensity-modulated radiotherapy (IMRT) plan was utilized as a base dose plan for compensating for the optimization-convergence error (OCE)
We retrospectively identified thirteen patients with malignancies of the nasal cavity, maxillary sinus and ethmoid sinus with stages T2–T4, N0 and M0, according to the American Joint Committee on Cancer (AJCC) 2010 7th edition staging criteria
Summary
The “base dose plan” function of Eclipse enabled the system to optimize a plan (as top dose plan) while taking another plan (as base dose plan) into account, aiming to achieve an optimal plan sum by making up for inadequacies (hot/cold spots) in the base dose plan. To establish the BDC approach for SNC cases, we needed to identify the optimal value of the x% of the prescribed NOF of base dose plan (NOF_ BDP). The VMAT plans were optimized based on the objectives applied in the initial IMRT plans and were further optimized until the clinically acceptable plans were achieved. Differences were considered to be statistically significant when P-value was < 0.05
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