<p>Dosimetric comparison of different algorithms in stereotactic body radiation therapy (SBRT) plan for non-small cell lung cancer (NSCLC)</p>

Abstract

Purposes The main aim of the study was to investigate the dosimetric difference between acuros XB algorithm (AXB), anisotropic analytic algorithm (AAA), and pencil beam convolution (PBC) algorithm in stereotactic body radiation therapy (SBRT) plan for non-small cell lung cancer (NSCLC). Patients and Methods Thirty-eight NSCLC patients were included. GTV, PTV, and organs at risk were delineated by the radiation oncologists. Three optimized SBRT plans for each patients were gained using three algorithms of AXB, AAA, and PBC with the identical plan parameters. Dosimetric endpoints were collected and compared among the three plans, including dosimetric criteria: V100%, V90%, PTV D min , D max , D mean , homogeneity index (HI), and Paddick conformity index (CI). Results AXB plan resulted in decreased V100% with a mean difference 6.14% compared with PBC plan (For V100%, AXB vs AAA vs PBC=93.44% vs 95.54% vs 99.58%, P <0.05). Three plans showed no significant difference as to the parameter V90%. AXB plan leaded to reduced D min of PTV compared with other two algorithms (For D min of PTV, AXB vs AAA vs PBC=4048cGy vs 4365Gy vs 4873Gy, P <0.05). PBC induced the enhanced trend of D max of PTV compared with other two algorithms (D max among three algorithms, P> 0.05); and increased the D mean of PTV in three algorithms with significant difference (For D mean of PTV, AXB vs AAA vs PBC=5332cGy vs 5330Gy vs 5785Gy, P <0.05). AXB algorithm achieved a similar plan conformity with other two algorithms (For CI, AXB vs AAA vs PBC=0.80 vs 0.85 vs 0.71, P >0.05). Conclusion For SBRT plan of NSCLC, AAA and PBC algorithms overestimate target coverage, AXB algorithm is recommended for the SBRT plan of NSCLC.

Dosimetric Impact of Acuros XB Dose-to-Water and Dose-to-Medium Reporting Modes on Lung Stereotactic Body Radiation Therapy and Its Dependency on Structure Composition

“…Regarding PTV coverage parameters, our results differed from those published in the literature. While we found a lower D 95 and no significant difference in D 98 when comparing AAA with AXB, it is widely reported that AAA overestimates these parameters and the minimum dose 7,9,[18][19][20][21][22][25][26][27]30 . The reason for this discrepancy is that while our plans were initially optimized for AXB and then recalculated, keeping identical beam parameters for AAA, most prior studies adopted the opposite method.…”

“…To our knowledge, ours is the largest study to date comparing AXB (Dm and Dw) and AAA in lung patients undergoing SBRT. Previous studies have included up to 37 patients 9,19,23,28 , or present results for Dm mode only 7,8,18,24,26,27 , and most report only PTV or lung-related dosevolume parameters 7,8,18,[20][21][22][23][24][25][27][28][29] .…”

“…Previous studies have included up to 37 patients 9 , 19 , 23 , 28 or present results for Dm mode only, 7 , 8 , 18 , 24 , 26 , 27 and most report only PTV or lung-related dose-volume parameters. 7 , 8 , 18 , 20 , 21 , 22 , 23 , 24 , 25 , 27 , 28 , 29 …”

“…Several studies have assessed the implications of using AXB for lung SBRT treatment planning [7][8][9][18][19][20][21][22][23][24][25][26][27][28][29][30] . In most cases, the impact in dose-volume parameters is below 2% except for the target coverage, which is considerably lower, and the Dw maximum dose in bony structures, which is significantly higher, in AXB-recalculated plans, as happens when MC is adopted 31 .…”

“…Several studies have assessed the implications of using AXB for lung SBRT treatment planning. 7 , 8 , 9 , 18 , 19 , 20 , 21 , 22 , 23 , 24 , 25 , 26 , 27 , 28 , 29 , 30 In most cases, the effect in dose-volume parameters is below 2% except for the target coverage, which is considerably lower, and the Dw maximum dose in bony structures, which is significantly higher, in AXB-recalculated plans, as happens when MC is adopted. 31 Certain studies used an older version of AXB (v10), 7 , 8 , 9 , 21 , 25 , 26 , 30 which differs from more recent versions in many respects, most importantly with regard to computed tomography (CT)-to-material conversions.…”