Purpose: The experimental verification of the Acuros XB (AXB) algorithm was conducted in a heterogeneous rectangular slab phantom, and compared to the Anisotropic Analytical Algorithm (AAA). The dosimetric impact of t...Purpose: The experimental verification of the Acuros XB (AXB) algorithm was conducted in a heterogeneous rectangular slab phantom, and compared to the Anisotropic Analytical Algorithm (AAA). The dosimetric impact of the AXB for stereotactic body radiation therapy (SBRT) and RapidArc planning for 16 non-small-cell lung cancer (NSCLC) patients was assessed due to the dose recalculation from the AAA to the AXB. Methods: The calculated central axis percentage depth doses (PDD) in a heterogeneous slab phantom for an open field size of 3 ×3 cm2 were compared against the PDD measured by an ionization chamber. For 16 NSCLC patients, the dose-volume parameters from the treatment plans calculated by the AXB and the AAA were compared using identical jaw settings, leaf positions, and monitor units (MUs). Results: The results from the heterogeneous slab phantom study showed that the AXB was more accurate than the AAA;however, the dose underestimation by the AXB (up to ?3.9%) and AAA (up to ?13.5%) was observed. For a planning target volume (PTV) in the NSCLC patients, in comparison to the AAA, the AXB predicted lower mean and minimum doses by average 0.3% and 4.3% respectively, but a higher maximum dose by average 2.3%. The averaged maximum doses to the heart and spinal cord predicted by the AXB were lower by 1.3% and 2.6% respectively;whereas the doses to the lungs predicted by the AXB were higher by up to 0.5% compared to the AAA. The percentage of ipsilateral lung volume receiving at least 20 and 5 Gy (V20 and V5 respectively) were higher in the AXB plans than in the AAA plans by average 1.1% and 2.8% respectively. The AXB plans produced higher target heterogeneity by average 4.5% and lower plan conformity by average 5.8% compared to the AAA plans. Using the AXB, the PTV coverage (95% of the PTV covered by the 100% of the prescribed dose) was reduced by average 8.2% than using the AAA. The AXB plans required about 2.3% increment in the number of MUs in order to achieve the same PTV coverage as in the AAA plans. Conclusion: The AXB is more accurate to use for the dose calculations in SBRT lung plans created with a RapidArc technique;however, one should also note the reduced PTV coverage due to the dose recalculation from the AAA to the AXB.展开更多
The purpose of the study was to evaluate a treatment dose using planning computed tomography (pCT) that was deformed to pre-treatment cone beam computed tomography (CBCT) for lung stereotactic body radiation therapy (...The purpose of the study was to evaluate a treatment dose using planning computed tomography (pCT) that was deformed to pre-treatment cone beam computed tomography (CBCT) for lung stereotactic body radiation therapy (SBRT) treatment. Five lung SBRT patients were retrospectively selected, and their daily CBCTs were employed in this study. Dosimetric comparison was performed between the original and recalculated plans from the deformed pCT (dose per fraction) by comparing a target coverage and organs at risk. Dose summation of five fractions was computed and compared to the original plan. A phantom study was conducted to evaluate the dosimetric accuracy for the dose per fraction. In the phantom study, the difference between the mean Hounsfield Unit (HU) values of the original and deformed pCTs is less than 0.5%. In patient study, the mean HU deviation of the five deformed pCTs compared to that of the original pCT was within ±5%, which is dosimetrically insignificant. While the internal target volume (ITV) shrank by 17% on average among the five patients, mean lung dose (MLD) increased by up to 7%, and D95% of PTV decreased slightly but stayed within 5%. Results showed that MLD might be a better indicative metric of normal lung dose than V20Gy as the ITV volume decreases. This study showed a feasibility to use a deformed pCT for evaluation of the dose per fraction and for a possible plan adaptation in lung SBRT cases. Readers should be cautious in selecting patients before clinical application due to the image quality of CBCT.展开更多
Purpose: To evaluate planning quality of Stereotactic body Radiotherapy (SBRT) with multiple lungmetastases generated by the Pinnacle and Tomotherapy planning systems, respectively. Methods and Materials: Nine randoml...Purpose: To evaluate planning quality of Stereotactic body Radiotherapy (SBRT) with multiple lungmetastases generated by the Pinnacle and Tomotherapy planning systems, respectively. Methods and Materials: Nine randomly selected patients diagnosed with non-small cell lung carcinoma with multiple lesions were planned with Philips Pinnacle (version 9.2, Fitchburg, WI) and Tomotherapy (version 4.2, Madison, WI), respectively. Both coplanar and non-coplanar IMRT plans were generated on Pinnacle system. A total dose of 60 Gy was prescribed to cover 95% of Planning Target Volume (PTV) in 3 fractions based on the RTOG0236 protocol prescription [1]. All plans with single isocenter setting were used for multiple lesions planning. A set of nine static beams were used for Pinnacle plansusing Direct Machine Parameters Optimization (DMPO) algorithm of RTOT0236 dose constraints. Planning outcomes such as minimum and mean doses, V95, D95 (95% of target volume receivesprescription dose), D5, and D1 to PTV, maximum dose to heart, esophagus, cord, trachea, brachial plexus, rib, chest wall, and liver, mean dose toliver, total lung, right and left lung, volume of chest wall receives 30 Gy, volume of lungs receives 5 Gy and 20 Gy (V5 and V20), conformity index (CI) and heterogeneity index (HI) were all reported for evaluation. Results: Mean volume of PTV was 37.77 ± 23.4 cm3. D95 of PTV with Tomotherapy, coplanar, non-coplanar plan was 60.2 ± 0.3 Gy, 58.6 ± 1.2 Gy, and 59.1 ± 0.7 Gy, respectively. Mean dose to PTV was lower for Tomotherapy (p 5 (p 1 (p = 0.001). CI was higher with Tomotherapyplans (p p 5 which needs more attention for toxicity analysis.展开更多
体部立体定向放射治疗(Stereotactic Body Radiation Therapy,SBRT)是应用立体定位技术和特殊射线装置,将多源、多线束或多野三维空间聚焦的高能射线聚焦于体内某一靶区,使病灶组织受到高剂量照射,周围正常组织受量减少,从而获得临床疗...体部立体定向放射治疗(Stereotactic Body Radiation Therapy,SBRT)是应用立体定位技术和特殊射线装置,将多源、多线束或多野三维空间聚焦的高能射线聚焦于体内某一靶区,使病灶组织受到高剂量照射,周围正常组织受量减少,从而获得临床疗效高,副作用小的一类放疗技术的总称,采用γ射线所完成的SBRT简称为γ刀,采用X射线所完成的SBRT简称为X刀。SBRT的优势是采用高分次剂量、短疗程分割模式,具有明显的放射生物学优势。无论是国外还是国内,SBRT治疗肿瘤的临床结果均令人鼓舞,治疗早期非小细胞肺癌的3年生存率和局控率均优于常规放疗,与手术效果无差异,而且副作用小,治疗肝癌和胰腺癌的局控率和生存率也获得了大幅度提高。我国的γ刀技术具有独特的剂量聚焦优势和完全自主知识产权,符合我国"十一五"科技自主创新的要求,而且疗效显著、性价比高、易于推广应用符合我国国情。但由于种种原因,SBRT技术在中国尚未引起足够重视,中国γ刀技术需要从设备完善、加大政府支持力度和规范临床应用三个方面进行改进,SBRT的健康发展对推动我国放射肿瘤专业发展具有重要意义。展开更多
目的:探究医用直线加速器立体定向放射治疗(stereotactic body radiotherapy,SBRT)在晚期非小细胞肺癌(NSCLC)中的疗效、安全性,并行成本-效果分析。方法:回顾性分析122例接受放射治疗的晚期NSCLC患者临床资料,根据放射治疗方法分为SBRT...目的:探究医用直线加速器立体定向放射治疗(stereotactic body radiotherapy,SBRT)在晚期非小细胞肺癌(NSCLC)中的疗效、安全性,并行成本-效果分析。方法:回顾性分析122例接受放射治疗的晚期NSCLC患者临床资料,根据放射治疗方法分为SBRT组(58例)及调强适形放射治疗(intensity-modulated radiotherapy,IMRT)组(64例),比较两组临床疗效、主要器官受照剂量及放射不良反应发生情况,并行成本-效果分析。结果:两组临床疗效、主要器官受照剂量及放射不良反应发生情况比较,差异均无统计学意义(P>0.05),但SBRT组成本-效果比低于IMRT组(P<0.05)。结论:SBRT与IMRT治疗晚期NSCLC疗效与安全性相当,但SBRT更具经济学优势。展开更多
Purpose: To investigate the feasibility of applying ANOVA newly proposed by Yukinori to verify the setup errors, PTV (Planning Target Volume) margins, DVH for lung cancer with SBRT. Methods: 20 patients receiving SBRT...Purpose: To investigate the feasibility of applying ANOVA newly proposed by Yukinori to verify the setup errors, PTV (Planning Target Volume) margins, DVH for lung cancer with SBRT. Methods: 20 patients receiving SBRT to 50 Gy in 5 fractions with a Varian iX linear acceleration were selected. Each patient was scanned with kV-CBCT before the daily treatment to verify the setup position. Two other error calculation methods raised by Van Herk and Remeijer were also compared to discover the statistical difference in systematic errors (Σ), random errors (σ), PTV margins and DVH. Results: Utilizing two PTV margin calculation formulas (Stroom, Van Herk), PTV calculated by Yukinori method in three directions were (5.89 and 3.95), (5.54 and 3.55), (3.24 and 0.78) mm;Van Herk method were (6.10 and 4.25), (5.73 and 3.83), (3.51 and 1.13) mm;Remeijer method were (6.39 and 4.57), (5.98 and 4.10), (3.69 and 1.33) mm. The volumes of PTV using Yukinori method were significantly smaller (P < 0.05) than Van Herk method and Remeijer method. However, dosimetric indices of PTV (D98, D50, D2) and for OARs (Mean Dose, V20, V5) had no significant difference (P > 0.05) among three methods. Conclusions: In lung SBRT treatment, due to fraction reduction and high level of dose per fraction, ANOVA was able to offset the effect of random factors in systematic errors, reducing the PTV margins and volumes. However, no distinct dose distribution improvement was founded in target volume and organs at risk.展开更多
<div style="text-align:justify;"> The arms-up position is the most common treatment position adopted for lung cancer patients treated with radiation therapy. However, many elderly or frail patients hav...<div style="text-align:justify;"> The arms-up position is the most common treatment position adopted for lung cancer patients treated with radiation therapy. However, many elderly or frail patients have shoulder problems and cannot tolerate such an overstretched position for an extended period. Therefore, the arms-down position becomes the only alternative for this group of patients during radiation therapy. Even though the arms-down position is not ideal, it does provide a stable and comfortable patient immobilization position for radiation treatments that require a longer delivery time, such as stereotactic body radiation therapy (SBRT). In this study, we designed a protocol to treat lung cancer patients with VMAT stereotactic body radiation therapy (VMAT SBRT) and deep inspiration breath-hold (DIBH) in the arms-down position. Our initial clinical experience with this protocol indicates that it is reliable for patient immobilization and accurate in delivered dosimetry. </div>展开更多
<div style="text-align:justify;"> <span style="font-family:Verdana;">The purpose of this study was to evaluate a planning strategy based on Acuros with density override in comparison wi...<div style="text-align:justify;"> <span style="font-family:Verdana;">The purpose of this study was to evaluate a planning strategy based on Acuros with density override in comparison with AAA without and with the override. Ten lung-tumor patients were selected with each PTV size around 2 - 4 cm and were imaged using slow scan, followed by four-dimensional (4D) imag</span><span style="font-family:Verdana;">ing limited to the target. On each phase-specific image, gross tumor </span><span style="font-family:Verdana;">volume (GTV) was contoured. Summed over all phases, an integrated GTV (iGTV) was generated and copied to the slow scan. A treatment plan was created using a dynamic-conformal-arc technique with AAA to prescribe 60 Gy to 95% of PTV (iGTV + 0.5 cm). Each AAA-based plan was regenerated by overriding the density of the setup margin of PTV by GTV density (modeling tumor-position uncertainty). It was also regenerated with Acuros and the override. The three plans were validated in 4D dose to PTV, after similarly overriding PTV density (phase-specific), accurately calculating with Acuros, and summing the phase-specific plans through organ/dose registration. The Acuros-based plan with the override, the AAA-based plan, and the AAA-based plan with the override provided 4D PTV doses of 63.9, 67.9, and 62 Gy at D95%, respectively, averaged over all patients. The override with Acuros and AAA produced lesser 4D doses, closer to the associated 3D doses, respectively, than that without the override, with better conformity and inhomogeneity. With the override in common, Acuros provided a greater dose to PTV than that by AAA. The Acuros with the override, which was more accurate than the AAA without the override, is clinically recommended.</span> </div>展开更多
Purpose: Stereotactic body radiation therapy (SBRT) has emerged as a standard treatment modality for medically inoperable early-stage lung cancer patients. The aim of this paper is to calculate radiobiological paramet...Purpose: Stereotactic body radiation therapy (SBRT) has emerged as a standard treatment modality for medically inoperable early-stage lung cancer patients. The aim of this paper is to calculate radiobiological parameters for a sample of 39 patients who underwent lung SBRT. Materials and Methods: For SBRT, a typical regimen of 50 Gy in 4 - 5 fractions results in local tumor control rates around 99.9%. We calculate dose volume histograms (DVHs) of targeted tumors and organs at risk for 39 patients. All patients received 4D imaging, and their internal treatment volumes (ITVs) were created by phase-based sorting of multiple CT datasets. Planning target volume (PTV) diameters ranged from 2.0 to 5.7 cm. The DVHs for the PTV and organs at risk were analyzed using a Biosuite algorithm to calculate the equivalent uniform dose (EUD), tumor control probability (TCP) via a Poisson model, and normal tissue complication probability (NTCP) via an LKB model. The radiobiological effects were analyzed by correlating EUD and TCP with PTV volumes. Results: The mean PTV volume was 31.60 ± 25.55 cc. The mean EUDs were 5.19 ± 2.84, 5.66 ± 4.95, 61.45 ± 29.18, 3.31 ± 5.92, 6.45 ± 5.18, and 12.22 ± 5.94 Gy for lungs, spinal cord, chest/ribs, heart, esophagus, and skin, respectively. On average, the heart had the lowest EUD and the chest/ribs had the highest (61.45 ± 29.18 Gy). The mean NTCPs were estimated at 3.75% ± 2.61%, 36.25% ± 36.42%, and 0.59% ± 1.48%, for the lungs, chest and esophagus, respectively. The NTCPs of spinal cord, heart, and skin were 0.00%. The mean TCP value was 99.72% ± 0.44%. The mean BED value for our study was 109.49 Gy. Conclusions: We have calculated radiobiological predictors based on DVHs for early-stage non-small cell lung cancer via SBRT. Our calculated predictors are compatible with previously published SBRT reports.展开更多
文摘Purpose: The experimental verification of the Acuros XB (AXB) algorithm was conducted in a heterogeneous rectangular slab phantom, and compared to the Anisotropic Analytical Algorithm (AAA). The dosimetric impact of the AXB for stereotactic body radiation therapy (SBRT) and RapidArc planning for 16 non-small-cell lung cancer (NSCLC) patients was assessed due to the dose recalculation from the AAA to the AXB. Methods: The calculated central axis percentage depth doses (PDD) in a heterogeneous slab phantom for an open field size of 3 ×3 cm2 were compared against the PDD measured by an ionization chamber. For 16 NSCLC patients, the dose-volume parameters from the treatment plans calculated by the AXB and the AAA were compared using identical jaw settings, leaf positions, and monitor units (MUs). Results: The results from the heterogeneous slab phantom study showed that the AXB was more accurate than the AAA;however, the dose underestimation by the AXB (up to ?3.9%) and AAA (up to ?13.5%) was observed. For a planning target volume (PTV) in the NSCLC patients, in comparison to the AAA, the AXB predicted lower mean and minimum doses by average 0.3% and 4.3% respectively, but a higher maximum dose by average 2.3%. The averaged maximum doses to the heart and spinal cord predicted by the AXB were lower by 1.3% and 2.6% respectively;whereas the doses to the lungs predicted by the AXB were higher by up to 0.5% compared to the AAA. The percentage of ipsilateral lung volume receiving at least 20 and 5 Gy (V20 and V5 respectively) were higher in the AXB plans than in the AAA plans by average 1.1% and 2.8% respectively. The AXB plans produced higher target heterogeneity by average 4.5% and lower plan conformity by average 5.8% compared to the AAA plans. Using the AXB, the PTV coverage (95% of the PTV covered by the 100% of the prescribed dose) was reduced by average 8.2% than using the AAA. The AXB plans required about 2.3% increment in the number of MUs in order to achieve the same PTV coverage as in the AAA plans. Conclusion: The AXB is more accurate to use for the dose calculations in SBRT lung plans created with a RapidArc technique;however, one should also note the reduced PTV coverage due to the dose recalculation from the AAA to the AXB.
文摘The purpose of the study was to evaluate a treatment dose using planning computed tomography (pCT) that was deformed to pre-treatment cone beam computed tomography (CBCT) for lung stereotactic body radiation therapy (SBRT) treatment. Five lung SBRT patients were retrospectively selected, and their daily CBCTs were employed in this study. Dosimetric comparison was performed between the original and recalculated plans from the deformed pCT (dose per fraction) by comparing a target coverage and organs at risk. Dose summation of five fractions was computed and compared to the original plan. A phantom study was conducted to evaluate the dosimetric accuracy for the dose per fraction. In the phantom study, the difference between the mean Hounsfield Unit (HU) values of the original and deformed pCTs is less than 0.5%. In patient study, the mean HU deviation of the five deformed pCTs compared to that of the original pCT was within ±5%, which is dosimetrically insignificant. While the internal target volume (ITV) shrank by 17% on average among the five patients, mean lung dose (MLD) increased by up to 7%, and D95% of PTV decreased slightly but stayed within 5%. Results showed that MLD might be a better indicative metric of normal lung dose than V20Gy as the ITV volume decreases. This study showed a feasibility to use a deformed pCT for evaluation of the dose per fraction and for a possible plan adaptation in lung SBRT cases. Readers should be cautious in selecting patients before clinical application due to the image quality of CBCT.
文摘Purpose: To evaluate planning quality of Stereotactic body Radiotherapy (SBRT) with multiple lungmetastases generated by the Pinnacle and Tomotherapy planning systems, respectively. Methods and Materials: Nine randomly selected patients diagnosed with non-small cell lung carcinoma with multiple lesions were planned with Philips Pinnacle (version 9.2, Fitchburg, WI) and Tomotherapy (version 4.2, Madison, WI), respectively. Both coplanar and non-coplanar IMRT plans were generated on Pinnacle system. A total dose of 60 Gy was prescribed to cover 95% of Planning Target Volume (PTV) in 3 fractions based on the RTOG0236 protocol prescription [1]. All plans with single isocenter setting were used for multiple lesions planning. A set of nine static beams were used for Pinnacle plansusing Direct Machine Parameters Optimization (DMPO) algorithm of RTOT0236 dose constraints. Planning outcomes such as minimum and mean doses, V95, D95 (95% of target volume receivesprescription dose), D5, and D1 to PTV, maximum dose to heart, esophagus, cord, trachea, brachial plexus, rib, chest wall, and liver, mean dose toliver, total lung, right and left lung, volume of chest wall receives 30 Gy, volume of lungs receives 5 Gy and 20 Gy (V5 and V20), conformity index (CI) and heterogeneity index (HI) were all reported for evaluation. Results: Mean volume of PTV was 37.77 ± 23.4 cm3. D95 of PTV with Tomotherapy, coplanar, non-coplanar plan was 60.2 ± 0.3 Gy, 58.6 ± 1.2 Gy, and 59.1 ± 0.7 Gy, respectively. Mean dose to PTV was lower for Tomotherapy (p 5 (p 1 (p = 0.001). CI was higher with Tomotherapyplans (p p 5 which needs more attention for toxicity analysis.
文摘体部立体定向放射治疗(Stereotactic Body Radiation Therapy,SBRT)是应用立体定位技术和特殊射线装置,将多源、多线束或多野三维空间聚焦的高能射线聚焦于体内某一靶区,使病灶组织受到高剂量照射,周围正常组织受量减少,从而获得临床疗效高,副作用小的一类放疗技术的总称,采用γ射线所完成的SBRT简称为γ刀,采用X射线所完成的SBRT简称为X刀。SBRT的优势是采用高分次剂量、短疗程分割模式,具有明显的放射生物学优势。无论是国外还是国内,SBRT治疗肿瘤的临床结果均令人鼓舞,治疗早期非小细胞肺癌的3年生存率和局控率均优于常规放疗,与手术效果无差异,而且副作用小,治疗肝癌和胰腺癌的局控率和生存率也获得了大幅度提高。我国的γ刀技术具有独特的剂量聚焦优势和完全自主知识产权,符合我国"十一五"科技自主创新的要求,而且疗效显著、性价比高、易于推广应用符合我国国情。但由于种种原因,SBRT技术在中国尚未引起足够重视,中国γ刀技术需要从设备完善、加大政府支持力度和规范临床应用三个方面进行改进,SBRT的健康发展对推动我国放射肿瘤专业发展具有重要意义。
文摘目的:探究医用直线加速器立体定向放射治疗(stereotactic body radiotherapy,SBRT)在晚期非小细胞肺癌(NSCLC)中的疗效、安全性,并行成本-效果分析。方法:回顾性分析122例接受放射治疗的晚期NSCLC患者临床资料,根据放射治疗方法分为SBRT组(58例)及调强适形放射治疗(intensity-modulated radiotherapy,IMRT)组(64例),比较两组临床疗效、主要器官受照剂量及放射不良反应发生情况,并行成本-效果分析。结果:两组临床疗效、主要器官受照剂量及放射不良反应发生情况比较,差异均无统计学意义(P>0.05),但SBRT组成本-效果比低于IMRT组(P<0.05)。结论:SBRT与IMRT治疗晚期NSCLC疗效与安全性相当,但SBRT更具经济学优势。
文摘Purpose: To investigate the feasibility of applying ANOVA newly proposed by Yukinori to verify the setup errors, PTV (Planning Target Volume) margins, DVH for lung cancer with SBRT. Methods: 20 patients receiving SBRT to 50 Gy in 5 fractions with a Varian iX linear acceleration were selected. Each patient was scanned with kV-CBCT before the daily treatment to verify the setup position. Two other error calculation methods raised by Van Herk and Remeijer were also compared to discover the statistical difference in systematic errors (Σ), random errors (σ), PTV margins and DVH. Results: Utilizing two PTV margin calculation formulas (Stroom, Van Herk), PTV calculated by Yukinori method in three directions were (5.89 and 3.95), (5.54 and 3.55), (3.24 and 0.78) mm;Van Herk method were (6.10 and 4.25), (5.73 and 3.83), (3.51 and 1.13) mm;Remeijer method were (6.39 and 4.57), (5.98 and 4.10), (3.69 and 1.33) mm. The volumes of PTV using Yukinori method were significantly smaller (P < 0.05) than Van Herk method and Remeijer method. However, dosimetric indices of PTV (D98, D50, D2) and for OARs (Mean Dose, V20, V5) had no significant difference (P > 0.05) among three methods. Conclusions: In lung SBRT treatment, due to fraction reduction and high level of dose per fraction, ANOVA was able to offset the effect of random factors in systematic errors, reducing the PTV margins and volumes. However, no distinct dose distribution improvement was founded in target volume and organs at risk.
文摘<div style="text-align:justify;"> The arms-up position is the most common treatment position adopted for lung cancer patients treated with radiation therapy. However, many elderly or frail patients have shoulder problems and cannot tolerate such an overstretched position for an extended period. Therefore, the arms-down position becomes the only alternative for this group of patients during radiation therapy. Even though the arms-down position is not ideal, it does provide a stable and comfortable patient immobilization position for radiation treatments that require a longer delivery time, such as stereotactic body radiation therapy (SBRT). In this study, we designed a protocol to treat lung cancer patients with VMAT stereotactic body radiation therapy (VMAT SBRT) and deep inspiration breath-hold (DIBH) in the arms-down position. Our initial clinical experience with this protocol indicates that it is reliable for patient immobilization and accurate in delivered dosimetry. </div>
文摘<div style="text-align:justify;"> <span style="font-family:Verdana;">The purpose of this study was to evaluate a planning strategy based on Acuros with density override in comparison with AAA without and with the override. Ten lung-tumor patients were selected with each PTV size around 2 - 4 cm and were imaged using slow scan, followed by four-dimensional (4D) imag</span><span style="font-family:Verdana;">ing limited to the target. On each phase-specific image, gross tumor </span><span style="font-family:Verdana;">volume (GTV) was contoured. Summed over all phases, an integrated GTV (iGTV) was generated and copied to the slow scan. A treatment plan was created using a dynamic-conformal-arc technique with AAA to prescribe 60 Gy to 95% of PTV (iGTV + 0.5 cm). Each AAA-based plan was regenerated by overriding the density of the setup margin of PTV by GTV density (modeling tumor-position uncertainty). It was also regenerated with Acuros and the override. The three plans were validated in 4D dose to PTV, after similarly overriding PTV density (phase-specific), accurately calculating with Acuros, and summing the phase-specific plans through organ/dose registration. The Acuros-based plan with the override, the AAA-based plan, and the AAA-based plan with the override provided 4D PTV doses of 63.9, 67.9, and 62 Gy at D95%, respectively, averaged over all patients. The override with Acuros and AAA produced lesser 4D doses, closer to the associated 3D doses, respectively, than that without the override, with better conformity and inhomogeneity. With the override in common, Acuros provided a greater dose to PTV than that by AAA. The Acuros with the override, which was more accurate than the AAA without the override, is clinically recommended.</span> </div>
文摘Purpose: Stereotactic body radiation therapy (SBRT) has emerged as a standard treatment modality for medically inoperable early-stage lung cancer patients. The aim of this paper is to calculate radiobiological parameters for a sample of 39 patients who underwent lung SBRT. Materials and Methods: For SBRT, a typical regimen of 50 Gy in 4 - 5 fractions results in local tumor control rates around 99.9%. We calculate dose volume histograms (DVHs) of targeted tumors and organs at risk for 39 patients. All patients received 4D imaging, and their internal treatment volumes (ITVs) were created by phase-based sorting of multiple CT datasets. Planning target volume (PTV) diameters ranged from 2.0 to 5.7 cm. The DVHs for the PTV and organs at risk were analyzed using a Biosuite algorithm to calculate the equivalent uniform dose (EUD), tumor control probability (TCP) via a Poisson model, and normal tissue complication probability (NTCP) via an LKB model. The radiobiological effects were analyzed by correlating EUD and TCP with PTV volumes. Results: The mean PTV volume was 31.60 ± 25.55 cc. The mean EUDs were 5.19 ± 2.84, 5.66 ± 4.95, 61.45 ± 29.18, 3.31 ± 5.92, 6.45 ± 5.18, and 12.22 ± 5.94 Gy for lungs, spinal cord, chest/ribs, heart, esophagus, and skin, respectively. On average, the heart had the lowest EUD and the chest/ribs had the highest (61.45 ± 29.18 Gy). The mean NTCPs were estimated at 3.75% ± 2.61%, 36.25% ± 36.42%, and 0.59% ± 1.48%, for the lungs, chest and esophagus, respectively. The NTCPs of spinal cord, heart, and skin were 0.00%. The mean TCP value was 99.72% ± 0.44%. The mean BED value for our study was 109.49 Gy. Conclusions: We have calculated radiobiological predictors based on DVHs for early-stage non-small cell lung cancer via SBRT. Our calculated predictors are compatible with previously published SBRT reports.
