A radiobiological and dosimetrical comparison between simultaneous integrated and sequential boost intensity-modulated arc treatment of locally advanced head-and-neck cancer.

Mandal, Abhijit; Choudhary, Sunil; Mani, Nilesh; Aggarwal, Sushil Kumar

Purpose The study aimed to compare the radiobiological and dosimetric parameters between sequential boost (SEQB) and simultaneous integrated boost (SIB) treatment regimen using intensity-modulated arc therapy technique in locally advanced head-and-neck cancer (LAHNC) patients. Materials and Methods A total of 24 previously untreated LAHNC patients were randomized into SIB (n= 11) and SEQB (n = 13) arms. The planning computed tomography data set was transferred to the treatment planning system. All the target volumes and organ at risk volumes were delineated. Single plan for SIB group and three plans (three phases) were generated for SEQB group of patients. Radiobiological and dosimetric parameters were compared. Results The BED10(planned) value for high-risk (HR) planning target volume (PTV) was same in both groups, whereas for intermediate-risk (IR) PTV and low-risk (LR) PTV, the values were higher in SEQB arm than SIB arm. The V95 values were 100% for all the target volumes in both arms of patients. The average D100 value for gross target volume, HR PTV, and IR PTV was higher in SEQB arm than that in the SIB arm. The average D100 value for LR PTV was higher in the SIB arm compared to that of the SEQB arm. The BED10(achieved) was calculated using D100 values of target volumes. The difference of BED10(achieved) values between SEQB arm and SIB arm further increased than the BED10(planned) values for all target volumes. The maximum doses for spinal cord, spinal cord planning risk volume, and brain stem were within the tolerance dose in both groups of patients. The left and right parotid glands sparing was comparable in both groups of patients. Average integral dose was higher in the SIB group than SEQB group. The average total monitor unit per fraction was higher in the SEQB arm than that in the SIB arm. Conclusion SIB regimen may be considered as more logical and efficient over SEQB regimen in the treatment of LAHNC with comparable radiobiological and dosimetric parameters.