비편평화여과기 빔을 이용한 폐 정위절제방사선치료를 위한 AAA와 Acuros XB 계산 알고리즘의 치료계획 비교 Comparison of Anisotropic Analytic Algorithm Plan and Acuros XB Plan for Lung Stereotactic Ablative Radiotherapy Using Flattening Filter-Free Beams원문보기
이 연구는 비편평화여과기(flattening filter-free, FFF) 빔을 이용한 폐 정위절제방사선치료(stereotactic ablative radiotherapy, SABR)에 대하여 서로 다른 선량계산 알고리즘의 선량적 효과를 조사하였다. SABR를 받은 10명의 폐암 환자를 대상으로하여 평가하였다. 모든 치료계획은 Eclipse 치료계획시스템의 Acuros XB (AXB) 알고리즘을 이용하여 수립되었다. 다른 선량계산 알고리즘과 비교를 위하여, 추가적으로 anisotropic analytic algorithm (AAA) 알고리즘을 적용한 치료계획을 재 수립하였다. 두 알고리즘 평가를 위해서, 치료표적과 손상위험장기의 선량체적히스토그램(dose-volume histogrim, DVH)를 분석하였다. 그리고 기술적 인자로써 계산시간과 총 MU 값을 평가하였다. DVH 비교분석을 통해, PTV의 최대선량은 AXB이 AAA 보다 5.2% 높았으며 최소선량은 4.4% 낮게 나타났다. PTV의 $V_{105%}$에서 7.06%까지 큰 차이를 나타났다. 폐의 최대선량은 AXB 치료계획에서 약간 크게 나타났다. 동측성 폐에 5, 10과 20 Gy 선량이 조사되는 체적은 AAA 보다 AXB에서 더 크게 나타났으나 대측성 폐에 대해서는 거의 비슷하게 나타났다. 척수와 심장에서 최대선량의 차이도 크지 않았다. 계산시간의 경우, AXB가 AAA보다 13.7% 정도 소요시간이 적었고 MU 값은 AXB에서 3.47% 더 많았다. 이 연구의 결과들은 회전조절치료 기법을 포함하여 FFF 빔이 적용된 폐 SABR 치료계획에서 AXB 알고리즘은 선량계산의 정확성과 계산시간의 감소의 장점을 제공할 수 있을 것이다.
이 연구는 비편평화여과기(flattening filter-free, FFF) 빔을 이용한 폐 정위절제방사선치료(stereotactic ablative radiotherapy, SABR)에 대하여 서로 다른 선량계산 알고리즘의 선량적 효과를 조사하였다. SABR를 받은 10명의 폐암 환자를 대상으로하여 평가하였다. 모든 치료계획은 Eclipse 치료계획시스템의 Acuros XB (AXB) 알고리즘을 이용하여 수립되었다. 다른 선량계산 알고리즘과 비교를 위하여, 추가적으로 anisotropic analytic algorithm (AAA) 알고리즘을 적용한 치료계획을 재 수립하였다. 두 알고리즘 평가를 위해서, 치료표적과 손상위험장기의 선량체적히스토그램(dose-volume histogrim, DVH)를 분석하였다. 그리고 기술적 인자로써 계산시간과 총 MU 값을 평가하였다. DVH 비교분석을 통해, PTV의 최대선량은 AXB이 AAA 보다 5.2% 높았으며 최소선량은 4.4% 낮게 나타났다. PTV의 $V_{105%}$에서 7.06%까지 큰 차이를 나타났다. 폐의 최대선량은 AXB 치료계획에서 약간 크게 나타났다. 동측성 폐에 5, 10과 20 Gy 선량이 조사되는 체적은 AAA 보다 AXB에서 더 크게 나타났으나 대측성 폐에 대해서는 거의 비슷하게 나타났다. 척수와 심장에서 최대선량의 차이도 크지 않았다. 계산시간의 경우, AXB가 AAA보다 13.7% 정도 소요시간이 적었고 MU 값은 AXB에서 3.47% 더 많았다. 이 연구의 결과들은 회전조절치료 기법을 포함하여 FFF 빔이 적용된 폐 SABR 치료계획에서 AXB 알고리즘은 선량계산의 정확성과 계산시간의 감소의 장점을 제공할 수 있을 것이다.
This study investigated the dosimetric effects of different dose calculation algorithm for lung stereotactic ablative radiotherapy (SABR) using flattening filter-free (FFF) beams. A total of 10 patients with lung cancer who were treated with SABR were evaluated. All treatment plans were created usin...
This study investigated the dosimetric effects of different dose calculation algorithm for lung stereotactic ablative radiotherapy (SABR) using flattening filter-free (FFF) beams. A total of 10 patients with lung cancer who were treated with SABR were evaluated. All treatment plans were created using an Acuros XB (AXB) of an Eclipse treatment planning system. An additional plans for comparison of different alagorithm recalcuated with anisotropic analytic algorithm (AAA) algorithm. To address both algorithms, the cumulative dose-volume histogram (DVH) was analyzed for the planning target volume (PTV) and organs at risk (OARs). Technical parameters, such as the computation times and total monitor units (MUs), were also evaluated. A comparison analysis of DVHs from these plans revealed the PTV for AXB estimated a higher maximum dose (5.2%) and lower minimum dose (4.2%) than that of the AAA. The highest dose difference observed 7.06% for the PTV $V_{105%}$. The maximum dose to the lung was also slightly larger in the AXB plans. The percentate volumes of the ipsilateral lung ($V_5$, $V_{10}$, $V_{20}$) receiving 5, 10, and 20 Gy were also larger in AXB plans than for AAA plans. However, these parameters were comparable between both AAA and AXB plans for the contralateral lung. The differences of the maximum dose for the spinal cord and heart were also small. The computation time of AXB plans was 13.7% shorter than that of AAA plans. The average MUs were 3.47% larger for AXB plans than for AAA plans. The results of this study suggest that AXB algorithm can provide advantages such as accurate dose calculations and reduced computation time in lung SABR plan using FFF beams, especially for volumetric modulated arc therapy technique.
This study investigated the dosimetric effects of different dose calculation algorithm for lung stereotactic ablative radiotherapy (SABR) using flattening filter-free (FFF) beams. A total of 10 patients with lung cancer who were treated with SABR were evaluated. All treatment plans were created using an Acuros XB (AXB) of an Eclipse treatment planning system. An additional plans for comparison of different alagorithm recalcuated with anisotropic analytic algorithm (AAA) algorithm. To address both algorithms, the cumulative dose-volume histogram (DVH) was analyzed for the planning target volume (PTV) and organs at risk (OARs). Technical parameters, such as the computation times and total monitor units (MUs), were also evaluated. A comparison analysis of DVHs from these plans revealed the PTV for AXB estimated a higher maximum dose (5.2%) and lower minimum dose (4.2%) than that of the AAA. The highest dose difference observed 7.06% for the PTV $V_{105%}$. The maximum dose to the lung was also slightly larger in the AXB plans. The percentate volumes of the ipsilateral lung ($V_5$, $V_{10}$, $V_{20}$) receiving 5, 10, and 20 Gy were also larger in AXB plans than for AAA plans. However, these parameters were comparable between both AAA and AXB plans for the contralateral lung. The differences of the maximum dose for the spinal cord and heart were also small. The computation time of AXB plans was 13.7% shorter than that of AAA plans. The average MUs were 3.47% larger for AXB plans than for AAA plans. The results of this study suggest that AXB algorithm can provide advantages such as accurate dose calculations and reduced computation time in lung SABR plan using FFF beams, especially for volumetric modulated arc therapy technique.
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문제 정의
The purpose of this study was to evaluate the difference in the dose distribution of AXB and AAA plans implemented in a commercial TPS for lung SABR with an FFF beam. We compared the dosimetric parameters for the target and OARs according to the AAA and AXB plans.
제안 방법
All calculations were performed using a new version of the Eclipse 11.0 TPS with AAA 11.0.34 and AXB 11.0.34 (Varian Medical Systems, Palo Alto, CA). Two dose-reporting modes are available in AXB: dose-to-water and dose-to-medium.
We used the SI to evaluate the detailed dose homogeneity for the PTV and CTV. It qualitatively provided significant information regarding the dosimetric spread across the PTV and CTV. The PTV coverage using the AXB was reduced than that for the AAA, as shown in Fig.
The Digital Imaging and Communications in Medicine (DICOM) CT data were electronically transferred to the Eclipse TPS for contouring and planning. Planning treatment volumes (PTVs) were created by adding 5-mm margins to the clinical treatment volume (CTV) in all directions. The OARs considered were the lungs, heart, and spinal cord.
The beam parameters of the clinical treatment plans in this study were set up in the Eclipse TPS, and the treatment plans were calculated using a volumetric modulated arc therapy (VMAT) technique with two partial arcs allowing the optimizer to use a maximum dose rate of 1400 monitor units (MUs)/min for a 6-MV FFF beam. The dose calculations were performed with inhomogeneity correction and 2.
The SABR immobilization platform (Body Pro-Lok, CIVCO, Orange City, IA, USA) was used to fix the thoracic and abdominal regions and reduce residual body motion. The computed tomography (CT) data of these patients with lung tumors who underwent SABR were used, and the scans were acquired with 2-mm slice spacing on the flat table top of a Philips Big-bore CT scanner. The treatment plans were created using different dose calculation algorithms in this study.
The beam parameters of the clinical treatment plans in this study were set up in the Eclipse TPS, and the treatment plans were calculated using a volumetric modulated arc therapy (VMAT) technique with two partial arcs allowing the optimizer to use a maximum dose rate of 1400 monitor units (MUs)/min for a 6-MV FFF beam. The dose calculations were performed with inhomogeneity correction and 2.5-mm grid resolution in all plans. In all plans, 48 Gy of radiation were delivered in four equal fractions to deliver a biological equivalent dose exceeding 100 Gy.
The computed tomography (CT) data of these patients with lung tumors who underwent SABR were used, and the scans were acquired with 2-mm slice spacing on the flat table top of a Philips Big-bore CT scanner. The treatment plans were created using different dose calculation algorithms in this study. The Digital Imaging and Communications in Medicine (DICOM) CT data were electronically transferred to the Eclipse TPS for contouring and planning.
대상 데이터
The dose-volume histogram (DVH) of the calculated SABR plans for lung cancer was generated in the Eclipse TPS. The average DVH of the PTV was generated for the AAA and AXB plans by averaging the data for the 10 analyzed patients. For the PTV and CTV, the mean dose, minimum dose, maximum dose (high point dose), and homogeneity were compared.
성능/효과
HI: homogeneity indices, CI: conformity indices, LCF: lesion coverage factor, HTCI: health tissue conformity index, CN: conformity number V95%, V100%, V105%: the volumes receiving 95%, 100%, and 105% of the prescribed dose, respectively.
37 Gy, respectively. Regarding the different calculation algorithms, the mean V95%, V100%, and V105% for the PTV displayed large differences, with the largest difference (7.06%) observed for the PTV V105%. However, V95% and V100% differed by no more than 0.
The optimization goals were to ensure that the entire CTV received 95% of the prescribed dose and for the PTV to cover 95% of the volume that received 95% of the prescribed dose, with no PTV hot spot receiving 107% or more of the prescribed dose. Doses exceeding 107% were permitted only inside the target.
These results mean that 95% (2 standard deviations) and 99% (3 standard devations) of PTV using the AXB is encompassed 44.11∼51.89 to 42.83∼53.17 Gy, and that using the AAA is encompassed 45.48∼50.52 to 44.43∼51.57 Gy, respectively.
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