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Objective To compare the dosimetric differences of four fluence smoothing (FS) levels of the Monaco system in intensity-modulated radiation therapy (IMRT) after rectal cancer surgery, and to provide a reference for FS selection in clinical practice. Methods A total of 15 postoperative patients with rectal cancer admitted in 2020 were selected. Under the same optimal conditions, FS was set to Off, Low, Medium, and High for IMRT planning. The data were analyzed by SPSS 20.0 software. The dosimetric parameters of planning target volume and organs at risk (OARs), the number of Segments, the number of monitor units (MUs), the estimated total delivery time (ETDT), and the gamma pass rate were compared between the four FS levels. Results The four FS levels resulted in clinically acceptable dosimetric parameters of the planning target volume and OARs, and there was no significant difference in dose distribution between FS levels. From FS-Off to FS-High, number of Segments, number of Mus, and ETDT decreased by 15.2%, 11.8%, and 6.7%, respectively, whereas gamma pass rate increased by 1.6%. Conclusion The IMRT plans at four FS levels can meet the clinical requirements. Considering the planning quality and execution efficiency, FS-High is recommended for postoperative IMRT of patients with rectal cancer.
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Objective To compare the dosimetric characteristics of non-coplanar and coplanar field technology in static intensity-modulated radiotherapy of gastric cancer patients, so as to provide a reference for clinical radiotherapy plan selection. Methods Thirty-six patients with gastric cancer were selected to receive intensity-modulated radiotherapy in Huanggang Central Hospital, which was designed plan A and B. Group A used 7-field coplanar technology, while Group B used 7-field non-coplanar technology. We compared the differences of the optimized monitor unit, the dosimetry of organs at risk and target areas between group A and group B. Results Both group A and B could meet the requirements of doctors. The homogeneity index (0.14 ± 0.02), the conformity index (0.98 ± 0.01), Dmin (4315.21 ± 16.74) cGy、Dmean (4679.28 ± 28.39) cGy and Dmax(4952.30 ± 33.26) cGy of target areas in group B were better than those of group A. Moreover, the monitor unit of group B was much lower than that of group A, and the difference was statistically significant (P < 0.05). The Dmax, Dmean, V15, V20 and V30 of the left and right kidneys in group B were lower than those of group A. The Dmax (3408.57 ± 46.03) cGy, Dmean (1250.32 ± 14.27) cGy and V20 (44.91% ± 6.67%) of spinal cord and the Dmax (3408.57 ± 46.03) cGy, Dmean (1720.55 ± 17.42) cGy, V20 (25.31% ± 7.78%) and V30 (18.52% ± 1.56%) of small intestine were also lower than those of group A. The differences were statistically significant (P < 0.05). Conclusion The non-coplanar field radiation plan has more advantages in terms of target dose distribution and protection of organs so that it can be more considerably used in the process of planning and design.
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Purpose: In this study, it is aimed to compare three different radiotherapy treatment planning techniques in terms of critical organ scoring index (COSI), two different conformity index (CI), tumor control probability (TCP), and normal tissue complication probability (NTCP) calculations in early (T1) glottic larynx carcinoma (T1GL). Furthermore, it is aimed to investigate these parameters compliance with dose-volume histograms (DVH) parameters. Materials and Methods: Ten T1GL patients were immobilized in a supine position with a head and neck thermoplastic mask. Treatment plans were created with opposed lateral fields (OLAFs) and intensity-modulated radiation therapy (IMRT) techniques with a total dose of 66 Gy in 33 fraction with 2 Gy/day. IMRT fields were selected as five fields (5IMRT) and seven fields (7IMRT). Dosimetric evaluation of three different treatment plans for T1GL carcinoma was performed in two consequential steps. First step was the assessment of planning target volume (PTV), all organs at risks (OARs), and normal tissue (NT) dose calculations according to given dose constraint directions and comparing the plans via DVH. In the second step, for PTV, the compatibility of DVH data with CIs-TCP was investigated where COSI-NTCP was compared with DVH for OARs. The DVH data were considered as reference in all evaluations. Results: The CIRTOG mean values were significantly closer to 1 with IMRT plans when compared to OLAF plans (P = 0.005). The CIPADDICK mean values revealed that OLAF plans were significantly worse than IMRT plans (P = 0.005). No statistically significant difference was found between all three plans in terms of homogeneity index mean values (P = 0.076). The calculated mean TCP values were significantly better for 7IMRT plans when compared to OLAF and 5IMRT plans (P = 0.007 and P = 0.017, respectively). Both NTCP and COSI evaluations, which is compatible with DVH, significantly favored OLAF plan for spinal cord and 7IMRT for thyroid gland. The COSI evaluations, which are compatible with DVH, significantly favored 7IMRT plan for carotid arteries and 5IMRT plan for NT. Conclusion: Our results demonstrated that CIPADDICK-TCP calculations for PTV and COSI-NTCP calculations for OARs were compatible with DVH in T1 GL plans. Therefore, we suggest such parameters as valuable tools for choosing the feasible one among multiple plans and even with different treatment machines
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Aim: The aim of this study is to identify an ideal location of isocenter in intensity-modulated radiotherapy (IMRT) treatment plans. Materials and Methods: A total of 28 clinical target volumes and 4 English capital letters (C, L, T, and H) target volumes were considered in this study. Two IMRT treatment plans were generated for each target volume in the ECLIPSETM treatment planning system (TPS), first one with isocenter automatically placed (ISOAUTO) by TPS and the second one with geometric center-based isocenter (ISOGEOM). The geometric center of a cuboid volume, which was formed encompassing around the target volume in sagittal, transverse, and frontal planes, is considered as the geometric center of the target volume as well as the isocenter (ISOGEOM) of the IMRT plans. While performing the IMRT treatment plans using the beam angle optimization and dose volume optimization, the normal tissue objectives and target volume objectives were kept similar in both the plans. The dosimetrical parameters between the two groups of plans were compared. Results: The distance between ISOGEOM and ISOAUTO ranged from 0.16 cm to 3.04 cm with a mean and median of 0.85 cm and 0.69 cm, respectively. The ISOGEOM-based IMRT plans exhibited statistically significant advantages in total monitor units reduction (100% of cases, P ≤ 0.001), total number of field reduction (66% of cases, P ≤ 0.001), and reduction of patient mean dose (69% of cases, P ≤ 0.001) over ISOAUTO-based IMRT plans. The conformity index, homogeneity index and target mean dose were comparable between both group of plans. Conclusion: Significant dosimetrical advantages may be observed, when the geometric centroid of target volume is considered as isocenter of IMRT treatment plan.
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Objective To analyze the effect of the new conformal index(nCI)and the conventional conformal index(CI)on the treament planning quality of lung stereotopic radiotherapy(SBRT).Methods A total of 19 peripheral lung cancer patients,treated with SBRT in Fujian Medical University Union Hospital from 2014 to 2017,were analyzed retrospectively.Each patient was planned twice yielding identical CI and nCI.The prescription to 95％of planning target volume(PTV)was 48 Gy in four fractions,and renormalization was performed when needed for nineteen nCI plans.The Wilcoxon signed-rank test was used to examine the dosimetric index.Results The dose conformity plots indicate that nCI does not only reflect the dose to the organ at risk outside tumor,but also represents the dose distribution in the PTV.In addition,nCI was stricter with treatment planning qualities when the dose around PTV was closer to the prescribed dose.The value of target coverage(TC),the ratio of out-of-target volumes receiving 105％prescribed dose to the target volume(R105％),the ratio of volume covered by 50％isodose line to the target volume(R50％),and the ipsilateral lung V20were 98.70％,0.56,5.53,15.59％in the CI plans,vs.90％,0,4.99,14.42％in the corresponding nCI plans,respectively.All index were significantly lower in the nCI group(Z ＝-3.823,-3.180,-3.823,-3.783,respectively,P＜0.05).The ratio of the maximum dose to the 2 cm external margin from the PTV(D2 cm)to the maximum dose to the PTV were 63.70％and 64.07％respectively in the two groups,and the differences were not statistially significant(P＞0.05).The conformity values denoted a clinically favorable value as 1 between D95％and D99％of nCI plans,yet were not applicable to CI plans.Conclusions It is more clinically relavant to evaluate lung SBRT plans using nCI,TC and other indicators collectively than using CI alone.
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With the development of technology, several treatment plans can be got easily. There are many parameters related to the treatment in each plan and it is not only complex but also time-consuming to analyze them. So it is difficult for radiation oncologists to choose a plan. In order to solve the problem, a fast tool was developed integrating parameters such as conformity index and homogeneity index. This paper reviewed the type development, formula and features of conformity index and homogeneity index, in order to provide reference for users.
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Objective To propose a new set of conformity indices ( CIs ) that may be useful for evaluating whether the prescribed doses to target volume and organs at risk ( OAR) in intensity-modulated radiotherapy ( IMRT ) or three-dimensional conformal radiotherapy ( 3DCRT ) plans meet clinical requirements. Methods A total of 30 patients' plans were randomly selected from the IMRT or 3DCRT plans for non-small cell lung cancer and analyzed with the newly defined CIs described in this article. The plans to be improved were selected according to the evaluating results, and two schemes were developed to improve these plans. Then, the differences in CI, Dmax , Dmin , and Dmean of the planning target volume ( PTV) , V5 and V20 of the normal lung, V30 and V40 of the heart, and Dmax of the spinal cord were investigated with the paired t-test. Results Among the 30 plans, the average volume covered by the prescribed isodose line ( VRI ) was 25% larger than the PTV, so the normal lung tissue with a volume approximately 25% of PTV was given the same dose as the target volume, and the volume covered by the prescribed isodose line in the target V ( C) R was only 75% of the volume VR. Ninety-five percent of the target volume received a full prescribed dose;only 5% of the target volume received less than the prescribed dose, but which was still within 90% of the prescribed dose. In the comparison between the original plans and the plans improved using the first scheme, CI2 , CI4 , CI5 , CI6 , and homogeneity index ( HI) were not significantly different ( P=0240-0780) , and CI1 and CI3 showed significant differences ( P=0002 and 0);Dmax , Dmin , and Dmean of the PTV, V5 and V20 of the normal lung, V30 and V40 of the heart, and Dmax of the spinal cord were not significantly different ( P=0211-0964) . In the comparison between the original plans and the plans improved using the second scheme, CI2 , CI4 , and CI5 were not significantly different ( P=0308, 0308, and 0106 ) , CI1 , CI3 , CI6 , and HI showed significant differences ( P= 0001-0014);Dmax , Dmin , and Dmean of the PTV, V5 and V20 of the normal lung, and Dmax of the spinal cord showed significant differences ( P=0008-0036 ) , and V30 and V40 of the heart were not significantly different ( P=0083 and 0080) . Conclusions The new set of CIs proposed in this paper may be a good tool for evaluating the conformity of the target and the prescribed dose to OAR and thus developing better individualized treatment plans.
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With the development of technology, several treatment plans can be got easily. There are many parameters related to the treatment in each plan and it is not only complex but also time-consuming to analyze them. So it is difficult for radiation oncologists to choose a plan. In order to solve the problem, a fast tool was developed integrating parameters such as conformity index and homogeneity index. This paper reviewed the type development, formula and features of conformity index and homogeneity index, in order to provide reference for users.
RESUMO
Objective To propose a new set of conformity indices ( CIs ) that may be useful for evaluating whether the prescribed doses to target volume and organs at risk ( OAR) in intensity-modulated radiotherapy ( IMRT ) or three-dimensional conformal radiotherapy ( 3DCRT ) plans meet clinical requirements. Methods A total of 30 patients' plans were randomly selected from the IMRT or 3DCRT plans for non-small cell lung cancer and analyzed with the newly defined CIs described in this article. The plans to be improved were selected according to the evaluating results, and two schemes were developed to improve these plans. Then, the differences in CI, Dmax , Dmin , and Dmean of the planning target volume ( PTV) , V5 and V20 of the normal lung, V30 and V40 of the heart, and Dmax of the spinal cord were investigated with the paired t-test. Results Among the 30 plans, the average volume covered by the prescribed isodose line ( VRI ) was 25% larger than the PTV, so the normal lung tissue with a volume approximately 25% of PTV was given the same dose as the target volume, and the volume covered by the prescribed isodose line in the target V ( C) R was only 75% of the volume VR. Ninety-five percent of the target volume received a full prescribed dose;only 5% of the target volume received less than the prescribed dose, but which was still within 90% of the prescribed dose. In the comparison between the original plans and the plans improved using the first scheme, CI2 , CI4 , CI5 , CI6 , and homogeneity index ( HI) were not significantly different ( P=0240-0780) , and CI1 and CI3 showed significant differences ( P=0002 and 0);Dmax , Dmin , and Dmean of the PTV, V5 and V20 of the normal lung, V30 and V40 of the heart, and Dmax of the spinal cord were not significantly different ( P=0211-0964) . In the comparison between the original plans and the plans improved using the second scheme, CI2 , CI4 , and CI5 were not significantly different ( P=0308, 0308, and 0106 ) , CI1 , CI3 , CI6 , and HI showed significant differences ( P= 0001-0014);Dmax , Dmin , and Dmean of the PTV, V5 and V20 of the normal lung, and Dmax of the spinal cord showed significant differences ( P=0008-0036 ) , and V30 and V40 of the heart were not significantly different ( P=0083 and 0080) . Conclusions The new set of CIs proposed in this paper may be a good tool for evaluating the conformity of the target and the prescribed dose to OAR and thus developing better individualized treatment plans.
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Objective To compare the effects of 6MV and 10MV-X-ray intensity modulated radiotherapy (IMRT) on non-small-cell lung cancer (NSCLC) . Methods We randomly selected 20 patients with NSCLC, 6MV and 10MV X-ray were used respectively for each NSCLC patient with IMRT plan design, the ADAC Pinnacle 8.0f treatment planning system was applied to provide the convolution/iteration algorithm, for the same target IMRT plan design with two kinds of energy. By comparing the dose volume histogram (DVH),PTV parameter (Dmean, Dmin and Dmax), conformal index (CI) and homogeneity index (HI),we analyzed the metrology parameters . Results 6MV and 10MV radiation therapy plan DVH, PTV parameters,CI,HI and isodose line was similar,no statistically significant differences. But target dose homogeneity and the degree of target coverage in high dose of 6MV plan was better than that in 10MV plan. Endanger organs (OAR) such as normal lung tissue, heart, esophagus and spinal cord had basically same dose amount. Conclusion 6MV X-ray plan may be the better choice of radiotherapy on NSCLC.