Preliminary analysis of a clinical trial for three-dimensional conformal radiation therapy after conservative surgery

Objective The aim of this study was to evaluate the efficacy, complications and cosmetic results of three-dimensional conformal radiation therapy for early breast cancer after conservative surgery.

Clinical observation of gemcitabine and concomitant three-dimensional conformal radiotherapy in the treatment of locally advanced non-small cell lung cancer

Objective： To evaluate the clinical effect of gemcitabine and concurrent three-dimensional conformal radiation therapy （3D-CRT） for locally advanced non-small cell lung cancer （NSCLC）. Methods： From April 2002 to June 2005, 38 patients with inoperable stage Ⅲ NSCLC were treated with gemcitabine and 3D-CRT simultaneously. Chemotherapy consisted of intravenously gemcitabine 350 mg/m^2 on days 1, 8, 15, 22, 29, 36.3D-CRT was delivered up to a total dose of 60-64 Gy with a 2.0 Gy dose fraction per day, 5 days per week. Results： The overall response rates of primary tumor and mediastinum metastatic node were 86.8% （33/38） and 90.6% （29/32） respectively, and 91.7% （22/24） and 78.6% （11/14） for squamous cell carcinoma and adenocarcinoma respectively. The acute side effects of patients were mostly myelosuppression, nausea, vomiting, radiation-induced esophagitis and pneumonitis （RTOG 1/11）, however, all of them were cured. Conclusion： Concurrent application of gemcitabine and 3D-CRT can improve the overall response rate for locally advanced NSCLC without aggravating the side effects.

Influences of Motion Artifacts on Three-Dimensional Reconstruction Volume and Conformal Radiotherapy Planning

Objective ：To investigate the influences of motion artifacts on three-dimensional （3D） reconstruction volume and conformal radiotherapy planning. Methods： A phantom which can mimic the clip motion of lung tumor along the cranial-caudal direction is constructed by step motor, small ball of polyethylene and potato. Ten different scan protocols were set and CT data of the phantom were acquired by using a commercial GE LightSpeedl6 CT scanner. The 3D reconstruction of the CT data was implemented by adopting volume-rendering technology of GE AdvantageSim 6.0 system. The reconstructed volumes of each target in different scan protocols were measured through 3D measuring tools. Thus, relative deviations of the reconstruction volumes between moving targets and static ones were determined. The three-dimensional conformal radiation therapy （3D- CRT） plans and conformal fields were created and compared for a static/moving target with the WiMRT treatment planning system （TPS）. Results：For a static target, there was no obvious difference among the 3D reconstruction volumes when the CT data were acquired with different pitches and slices. The appearance of 3D reconstruction volume and 3D conformal field of a moving target was quite different from that of static one. The maximum relative deviation is nearly 90% for a moving target scanned with different scan protocols. The relative deviations are variable among the different targets, about from -39.8% to 89.5% for a smaller target and from - 18.4% to 20.5% for a larger one. Conclusion ：The motion artifacts have great effects on 3 D-CRT planning and reconstruction volume, which will greatly induce distorted conformal radiation fields and false DVHs for a moving target.

Analysis of the efficacy and safety of conventional radiotherapy of chest wall and clavicular field and three-dimensional conformal radiotherapy in patients after modified radical mastectomy

Objective:To explore the efficacy and safety of conventional radiotherapy of chest wall and clavicular field and three-dimensional conformal radiotherapy in patients after modified radical mastectomy.Methods: A total of 84 patients who were admitted in our hospital after modified radical mastectomy were included in the study and divided into the conventional radiotherapy group (n=42) and the three-dimensional conformal radiotherapy group (n=42) according to different radiotherapy methods. The patients in the conventional radiotherapy group were given conventional radiotherapy of chest wall and clavicular field, while the patients in the three-dimensional conformal radiotherapy group were given three-dimensional conformal radiotherapy. The serum tumor markers and peripheral blood T lymphocyte subsets 6-8 weeks after treatment in the two groups were detected. The clinical efficacy, and toxic and side effects in the two groups were evaluated.Results: The serum CA15-3, CA125, CEA, and CK19 levels after treatment in the two groups were significantly reduced when compared with before treatment, CD3+,CD4+, and CD4+/CD8+ were significantly elevated, while CD8+ was significantly reduced when compared with before treatment, but the comparison of the above indicators between the two groups was not statistically significant. The occurrence rate of radioactive skin damage and pneumonia after treatment in the conventional radiotherapy group was significantly higher than that in the three-dimensional conformal radiotherapy group. Conclusions:The two kinds of radiotherapy schemes have an equal efficacy, but the toxic and side effects of three-dimensional conformal radiotherapy are significantly lower than those by the conventional radiotherapy, with a certain advantage.

Evaluation of 3D-CRT and VMAT Radiotherapy Plans for Left Breast Cancer with Regional Lymph Nodes Irradiation

Introduction: Radiation therapy after breast surgery is an integral part of the treatment of early breast cancer. The goal of radiation therapy is to achieve the best possible coverage of the planning target volume (PTV), while reducing the dose to organs at risk (OARs) which are normal tissues whose sensitivity to irradiation could cause damage that can lead to modification of the treatment plan. In the last decade, radiation oncologist started to use the Intensity Modulated Radiotherapy (IMRT) and Volumetric Modulated Arc Therapy (VMAT) for irradiating the breast, in order to achieve better dose distribution and target dose to the PTV and OAR. The aim of this study is to compare 2 external radiotherapy techniques (VMAT vs 3D) for patients with node-positive left breast cancer. Patients and Methods: We randomly selected 10 cases of postoperative radiotherapy for breast cancer in our hospital. The patients are all female, the average age was 45.4 years old, and the primary lesions are left breast. The ANOVA test was used to compare the mean difference between subgroups, and the p value Results: Dose volume histogram (DVH) was used to analyze each evaluation dose of clinical target volume (CTV) and organs at risk (OARs). Compared to 3DCRT plans, VMAT provided more uniform coverage to the breast and regional lymph nodes. The max point dose for tVMAT was lower on average (106.4% for VMAT versus 109% for 3DCRT). OAR sparing was improved with tVMAT, with a lower average V17Gy for the left lung (27.91% for VMAT versus 30.04% for 3DCRT, p and lower for V28Gy (13.75% for VMAT versus 22.34% for 3DCRT, p = 0.01). We also found a lower V35Gy for the heart on VMAT plan (p = 0.02). On the contrary, dose of contralateral breast was lower in 3DCRT than VMAT (0.59 Gy vs 3.65 Gy, p = 0.00). Conclusion: The both types of plans can meet the clinical dosimetry demands of postoperative radiotherapy for left breast cancer. The VMAT plan has a better conformity, but 3CDRT can provide a lower dose to the contralateral organs (breast and lung) to avoid the risk of secondary cancers.

Simultaneous modulated accelerated radiation therapy for esophageal cancer:A feasibility study

AIM: To establish the feasibility of simultaneous modulated accelerated radiation therapy (SMART) in esophageal cancer (EC).

Study of the impact of CT/CT image fusion radiotherapy on V_(20) and radiation pneumonitis of non-small cell lung cancer

Objective:The aim of our study was to investigate the value of CT/CT image fusion radiation treatment planning in non-small cell lung cancer(NSCLC) and the impact on V20 and radiation pneumonitis(RP).Methods:Patients who were pathologically or cytologically diagnosed of stage IIIA and IIIB NSCLC were treated with three-dimensional conformal radiation therapy(4000 cGy).Forty patients got at least 25% tumor reduction were randomly divided into two groups:group A of regular shrink field radiotherapy(20 cases) and group B of CT/CT image fused shrink field radiotherapy(20 cases).Dosage reached 6600 cGy.Clinical data,V20 and RP were observed within 3 months after radiotherapy.Statistical analysis was conducted for the NSCLC patients.Results:22.5%(9/40) patients got RP during follow-up.Group A accounted for 6 cases(30%),and group B had 3 cases(15%).There was no marked difference between the two groups(P = 0.256),univariate analysis revealed that the IV20 of A and B groups,and IV20 and CV20 of all patients were statistically related to the incidence of RP(P < 0.05).With Wilcoxon method assay,the ipsilateral lung V20 and contralateral lung V20 had statistical significance between the two groups(P < 0.05).Conclusion:The CT/CT image infusion treatment planning could increase the radical dosage with better tumor control probability but won't increase adverse reaction.

The Effect of Absorbed Dose to Organs at Risk Following Craniospinal Irradiation Using Different Radiotherapy Techniques

Introduction: In medulloblastoma patients craniospinal irradiation is an important element the treatment. Our study aimed to evaluate the effect of absorbed dose to organs at risk using the hybrid intensity-modulated radiation therapy (IMRT) versus three-dimensional conformal radiotherapy (3DCRT) for craniospinal irradiation (CSI) in average risk medulloblastoma patients. Materials and Methods: In this study, thirteen medulloblastoma patients were included. The prescribed total dose to the planning target volume (PTV) was 23, 40 Gy in 13 fractions. Two radiotherapy techniques, three dimensional conformal radiotherapy (3DCRT) and hybrid intensity modulated radiotherapy (IMRT) were used to treat these patients. The coverage of the Target was evaluated using the D mean, D95%, D2%, D98% and V95%. Other parameters were also compared such as Integral dose (ID), Homogeneity index (HI) and doses to the organs at risk (OARs). Results: There was no significant difference in the mean dose received by the PTV-Brain or the dose received by 95% and 98% of PTV volume using the two techniques. For PTV-Spine, the percentage volume receiving 95% of the total dose increased significantly in the hybrid IMRT technique compared to the conformal technique. So, hybrid IMRT plan achieved the best coverage for PTV spine. Lower dose for OAR was delivered by 3DCRT, except the heart and thyroid, hybrid IMRT achieved better sparing. All plans resulted in the same dose homogeneity index (DHI) for PTV-Brain. For PTV-Spine, hybrid IMRT technique achieved better dose homogeneity compared to 3DCRT technique (1.09 vs. 1.12;p > 0.05). Conclusions: hybrid IMRT technique can be realized on conformal technique because it achieved better dose coverage for the (PTV) and organ at risk (OAR). 3DCRT reduced mean dose to most OARS, except the heart and thyroid. Therefore, the hybrid IMRT technique may be a CSI treatment alternative to 3DCRT.

Helical tomotherapy and volumetric modulated arc therapy:New therapeutic arms in the breast cancer radiotherapy

AIM To analyse clinical and dosimetric results of helical tomotherapy(HT) and volumetric modulated arc therapy(VMAT) in complex adjuvant breast and nodes irradiation.METHODS Seventy-three patients were included(31 HT and 42 VMAT). Dose were 63.8 Gy(HT) and 63.2 Gy(VMAT) in the tumour bed, 52.2 Gy in the breast, 50.4 Gy in supraclavicular nodes(SCN) and internal mammary chain(IMC) with HT and 52.2 Gy and 49.3 Gy in IMC and SCN with VMAT in 29 fractions. Margins to particle tracking velocimetry were greater in the VMAT cohort(7 mm vs 5 mm).RESULTS For the HT cohort, the coverage of clinical target volumes was as follows: Tumour bed: 99.4% ± 2.4%; breast: 98.4% ± 4.3%; SCN: 99.5% ± 1.2%; IMC:96.5% ± 13.9%. For the VMAT cohort, the coverage was as follows: Tumour bed: 99.7% ± 0.5%, breast: 99.3% ± 0.7%; SCN: 99.6% ± 1.4%; IMC: 99.3% ± 3%. For ipsilateral lung, Dmean and V20 were 13.6 ± 1.2 Gy, 21.1% ± 5%(HT) and 13.6 ± 1.4 Gy, 20.1% ± 3.2%(VMAT). Dmean and V30 of the heart were 7.4 ± 1.4 Gy, 1% ± 1%(HT) and 10.3 ± 4.2 Gy, 2.5% ± 3.9%(VMAT). For controlateral breast Dmean was 3.6 ± 0.2 Gy(HT) and 4.6 ± 0.9 Gy(VMAT). Acute skin toxicity grade 3 was 5% in the two cohorts.CONCLUSION HT and VMAT in complex adjuvant breast irradiation allow a good coverage of target volumes with an acceptable acute tolerance. A longer follow-up is needed to assess the impact of low doses to healthy tissues.

Accelerated partial breast irradiation:Current evidence and future developments

Whole breast irradiation after breast-conserving surgery for early breast cancer has become one of the standard treatment modes for breast cancer and yields the same effect as radical surgery.Accelerated partial breast irradiation(APBI)as a substitute for whole breast irradiation for patients with early breast cancer is a hot spot in clinical research.APBI is characterised by simple high-dose local irradiation of the tumour bed in a short time,thus improving convenience for patients and saving costs.The implementation methods of APBI mainly include brachytherapy,external beam radiation therapy,and intraoperative radiotherapy.This review provides an overview of the clinical effects and adverse reactions of the main technologies of APBI and discusses the prospects for the future development of APBI.

Dosimetric evaluation of CR, 3DCRT and two types of IMRT for breast cancer after conservative surgery

Objective: The purpose of this study was to compare the dose distribution and dose volume histogram (DVH) of the planning target volume (PTV) and organs at risk (OARs) among conventional radiation therapy (CR), three-dimensional conformal radiation therapy (3DCRT), two-step intensity-modulated radiation therapy (TS-IMRT) and direct machine parameter optimization intensity-modulated radiation therapy (DMPO-IMRT) after breast-conserving surgery. Methods: For each of 20 randomly chosen patients, 4 plans were designed using 4 irradiation techniques. The prescribed dose was 50 Gy/2 Gy/25 f, 95% of the planning target volume received this dose. The cumulated DVHs and 3D dose distributions of CR, 3DCRT, TS-IMRT and DMPO-IMRT plans were compared. Results: For the homogeneity indices, no statistically significant difference was observed among CR, 3DCRT, TS-IMRT and DMPO-IMRT while the difference of the conformality indices were statistically significant. With regard to the organs at risk, IMRT and 3DCRT showed a significantly fewer exposure dose to the ipsilateral lung than CR in the high-dose area while in the low-dose area, IMRT demonstrated a significant increase of exposure dose to ipsilateral lung, heart and contralateral breast compared with 3DCRT and CR. In addition, the monitor units (MUs) for DMPO-IMRT were approximately 26% more than those of TS-IMRT and the segments of the former were approximately 24% less than those of the latter. Conclusion: Compared with CR, 3DCRT and IMRT improved the homogeneity and conformity of PTV, reduced the irradiated volume of OARs in high dose area but IMRT increased the irradiated volume of OARs in low dose area. DMPO-IMRT plan has fewer delivery time but more MUs than TS-IMRT.

The impact of intensity modulated radiotherapy on the skin dose for deep seated tumors

Objective: The purpose of this study was to investigate the impact of intensity modulated radiotherapy (IMRT) on surface doses for brain, abdomen and pelvis deep located tumors treated with 6 MV photon and to evaluate the skin dose calculation accuracy of the XIO 4.04 treatment planning system. Methods: More investigations for the influences of IMRT on skin doses would increase its applications for many treatment sites. Measuring skin doses in real treatment situations would reduce the uncertainty of skin dose prediction. In this work a pediatric human phantom was covered by a layer of 1 mm bolus at three treatment sites and thermoluminescent dosimeter (TLD) chips were inserted into the bolus at each treatment site before CT scan. Two different treatment plans [three-dimensional conformal radiation therapy (3DCRT) and IMRT] for each treatment sites were performed on XIO 4.04 treatment planning system using superposition algorism. Results: The results showed that the surface doses for 3DCRT were higher than the surface doses in IMRT by 1.6%, 2.5% and 3.2% for brain, abdomen and pelvis sites respectively. There was good agreement between measured and calculated surface doses, where the calculated surface dose was 15.5% for brain tumor calculated with 3DCRT whereas the measured surface dose was 12.1%. For abdomen site the calculated surface dose for IMRT treatment plan was 16.5% whereas the measured surface dose was 12.6%. Conclusion: The skin dose in IMRT for deep seated tumors is lower than that in 3DCRT which is another advantage for the IMRT. The TLD readings showed that the difference between the calculated and measured point dose is negligible. The superposition calculation algorism of the XIO 4.04 treatment planning system modeled the superficial dose well.

乳腺癌保乳术后采用APBI-IMRT的效果

目的:探讨乳腺癌保乳术后采用加速部分乳腺调强放疗(accelerated partial breast irradiation with intensitymodulated radiation therapy,APBI-IMRT)的效果。方法:选择2018年6月—2022年9月南京大学医学院附属苏州医院收治的82例行乳腺癌保乳术患者作为研究对象,以随机数表法将患者分为对照组与研究组,各41例。对照组应用常规放疗,研究组应用APBI-IMRT,比较两组肿瘤标志物、危险器官剂量、心功能指标。结果:治疗前,两组肿瘤标志物、心功能指标比较,差异无统计学意义(P>0.05);治疗后,两组癌胚抗原(carcinoembryonic antigen,CEA)、β_(2)-微球蛋白(β_(2)-Microglobulin,β_(2)-MG)、细胞角蛋白19片段(cytokeratin 19 fragment,CYFRA21-1)、甲胎蛋白(alpha fetoprotein,AFP)水平、左房收缩末期内径(left atrial end-systolic diameter,LADs)、左室舒张末期内径(left ventricular end diastolic dimension,LVDD)、射血分数(ejection fraction,EF)、左心室短轴缩短率(fraction shortening,FS)较治疗前降低,且研究组肿瘤标志物低于对照组,但心功能指标高于对照组,差异有统计学意义(P<0.05)。研究组危险器官剂量低于对照组,差异有统计学意义(P<0.05)。结论:APBI-IMRT在乳腺癌保乳术后应用可增强治疗效果,降低对心肺功能的损伤。

早期乳腺癌保乳术后部分乳腺三维适形加速外照射剂量学研究

【目的】本研究通过对早期乳腺癌保乳术后部分乳腺三维适形加速外照射(APBI-3DCRT)计划设计的研究,旨在探讨中国女性早期乳腺癌保乳术后APBI-3DCRT剂量学分布特点及剂量学的可行性。【方法】选择50例保乳术后T1～2N0M0病例,利用三维治疗计划系统设计APBI-3DCRT计划及全乳腺照射(WBI)计划。按RTOG0319标准对50例APBI-3DCRT计划进行剂量学可行性评价;并比较正常组织在APBI-3DCRT和WBI计划中受量情况。【结果】50例APBI-3DCRT计划中评为Ⅰ级1例(2%);Ⅱ级46例(92%);Ⅲ级3例(6%)。与WBI相比,评价为Ⅰ～Ⅱ级APBI-3DCRT计划的患侧肺平均剂量(Dmean)以及至少接受20 Gy照射的体积百分比(V20)分别从9.259 Gy减少至1.637 Gy和从15.53%到1.79%,心脏的Dmean和V20分别从1.826 Gy减少至0.305 Gy和从3.14%到0.04%,对侧肺的最大剂量(Dmax)和Dmean分别从2.809 Gy减少至0.236 Gy和从1.107 Gy到0.102 Gy,对侧乳腺的Dmax和Dmean分别从2.391 Gy减少至0.231 Gy和从0.984 Gy到0.098 Gy,甲状腺的Dmax和Dmean分别从0.494 Gy减少至0.203 Gy和从0.203 Gy到0.078 Gy(P<0.05)。【结论】与WBI相比,APBI-3DCRT可以减少正常组织受照射的体积及照射剂量,有利于减轻正常组织的放射损伤;中国女性早期乳腺癌保乳术后进行APBI-3DCRT在剂量学上是可行的,建议进行Ⅰ/Ⅱ期的临床研究。

Ⅰ、Ⅱ期乳腺癌保乳术后的三维适形调强放射治疗

目的 对Ⅰ、Ⅱ期乳腺癌施行保乳术后的病人进行根治性三维适形调强放射治疗,提高局部控制率,减轻放疗副作用,提高了生存质量。方法 2 0 0 4年4月～2 0 0 4年1 0月的1 1例接受过标准保存乳房手术的Ⅰ、Ⅱ期乳腺癌病人,均为女性,年龄31～4 6岁,平均34.7岁。术前触诊肿瘤大小为6mm～30mm ,术后病理结果为:单纯癌4例、浸润性导管癌5例、高分化管状腺癌1例、中分化腺癌1例。手术后三个月内接受三维适形调强放射治疗。乳房切线照射剂量4 7～5 0Gy/ 2 4～31次,局部电子线补量1 0～1 5Gy/ 5～8次。结果 全部病人顺利完成全程放疗,最长1例接受放疗后已经2年半,局部及全身未见复发征象,乳房外观形状良好,放疗反应轻微。结论 通过对Ⅰ、Ⅱ期乳腺癌病人进行三维适形调强放射治疗,达到了提高病人的生存质量,提高肿瘤控制率的目的。

早期乳腺癌保乳术及术后治疗的研究进展

早期乳腺癌治疗手段已经由传统的根治手术发展到现在的保乳术结合术后治疗。保乳术后的四种治疗方式分别是放疗、化疗、内分泌治疗及综合治疗。保乳术后进行放射治疗对预后具有重要意义,目前常用的部分照射技术手段有组织插植,三维适形体外照射,腔内照射,术中放射治疗。研究分析早期乳腺癌保乳术及术后治疗的现状可积极合理地提高临床诊疗水平。

乳腺癌保乳术后三种放疗技术剂量学评价

目的:比较乳腺癌保乳术后常规放疗(CR)、三维适形(3D-CRT)放疗、调强适形(IMRT)放疗靶区剂量均匀性、危及器官受照体积等方面的差异。方法:随机选择10例乳腺癌患者,为每例患者设计上述三种照射技术的治疗计划。处方剂量为50Gy/25次。所有计划都使95%靶区体积达到处方剂量要求。根据积分剂量体积直方图(DVH)比较靶区受量和相关正常器官受量的差异和剂量分布。结果:CR、3D-CRT、IMRT靶区均匀性指数分别为1.16±0.03、1.15±0.03和1.14±0.02(P=0.279),适形度指数分别为0.61±0.05、0.65±0.06和0.69±0.06(P=0.025);三种放疗技术中患侧肺V30分别为19.39±3.09、15.53.±3.98、15.68±4.38(P=0.057),V20分别为22.26±3.52、18.87±4.24、20.68±4.52(P=0.202),V10分别为26.68±3.72、23.96±4.76、34.27±14.02(P=0.039),V5分别为33.71±3.70、31.66±5.49、49.81±24.25(P=0.018);对侧乳腺V3分别为3.31±3.74、2.37±3.11、14.24±3.81(P=0.007);心脏V5分别为19.99±17.22、13.77±11.10、38.42±29.95(P=0.037)。结论:与CR相比,3D-CRT和IMRT能够改善靶区均匀性和适形度,并降低患侧肺的高剂量受照体积,但IMRT同时增加了患侧肺、对侧乳腺、心脏低剂量受照体积。

乳腺癌保乳术后常规、三维适形和直接子野优化调强放疗技术剂量学评估

目的:比较乳腺癌保乳术后常规放疗(CR)、三维适形(3D-CRT)放疗、直接子野优化调强适形(DMPO-IMRT)放疗靶区剂量分布及危及器官受照体积等方面的差异。方法:随机选择10位乳腺癌患者,为每位患者设计上述三种照射技术的治疗计划。处方剂量为50 Gy/2 Gy/25次。所有计划都使95%靶区体积达到处方剂量要求。根据积分剂量体积直方图(DVH)比较靶区受量和相关正常器官受量的差异和剂量分布。结果:三种技术靶区均匀性指数(HI)和适形度指数(CI)差异均有显著性意义(P=0.049,P=0.001),其中尤以DMPO-IMRT的指标最佳。与CR相比,3DCRT降低了患侧肺、对侧乳腺和心脏在各个剂量区的受照体积,而DMPO-IMRT增大了患侧肺(V20、V30除外)、对侧乳腺和心脏的受照体积。与3DCRT相比,DMPO-IMRT增大了患侧肺(V30除外)、对侧乳腺和心脏的受照体积。结论:与CR相比,3D-CRT和DMPO-IMRT改善了靶区的均匀性和适形度。与此同时,3DCRT降低了本研究中各个剂量区危及器官的受照体积,DMPO-IMRT在降低患侧肺高剂量受照体积的同时,增大了患侧肺、对侧乳腺、心脏的低剂量受照体积。

乳腺癌根治术后适形和调强混合放疗计划与单纯调强放疗计划的剂量学比较

目的比较乳腺癌根治术后适形(3-Dimensional Conformal Radiation Therapy,3D-CRT)和调强(Intensity Modulated Radiotherapy,IMRT)混合放疗与单纯IMRT的剂量学分布,为乳腺癌根治术后放疗方法的选择和应用提供依据。方法选取20例左乳腺癌根治术后患者,针对每个患者分别设计CRT和IMRT混合放疗计划与单纯IMRT计划,处方剂量均为50 Gy/25 次,比较两种计划的靶区和危及器官的剂量学差异。结果两种计划中95%等剂量曲线包绕计划靶区的体积相似,分别为(99.18±0.32)%和(99.43±0.47)%,无显著差异(P>0.05);混合计划计划靶区的V105%、V110%值分别与单纯IMRT计划的对应值接近(P>0.05);混合计划的剂量适形度指数(Conformity Index,CI)、剂量均匀性指数(Homogeneity Index,HI)均优于单纯IMRT计划(P<0.05)。与单纯IMRT计划相比,混合计划患侧肺V30、V20、V5分别降低了2.68%、3.25%和27.38%,同时肺平均剂量(Mean Lung Dose,MLD)由10.21 Gy下降至8.35 Gy(P<0.05);混合放疗计划心脏V30、V40和V50分别降低了3.18%、2.27%和1.52%(P<0.05)。结论与单纯IMRT计划相比,CRT和IMRT混合放疗计划在剂量分布及适形度方面效果更好,且降低了肺、心脏等重要器官的照射剂量,具有更好的应用效果。

调整等中心技术在乳腺癌三维适形放疗中的应用

目的:比较乳腺癌放疗中,采用传统切线野、适形和调整等中心三种照射技术对改善靶区剂量均匀性和保护正常组织的作用,以改进放射治疗方法。方法:随机选择6位行全乳放疗的乳腺癌患者,为每位患者各设计上述的三种照射技术的治疗计划,给予90%PTV靶体积45 Gy的处方剂量,分别比较它们的靶区平均剂量、剂量均匀性指数、重要器官平均剂量,以及剂量分布图和DVH图。结果:三种技术靶区剂量均匀性方差分析差异具有统计学意义(P<0.01),调整等中心技术的靶区均匀性最好,而传统的切线照射技术最差。三种技术在保护重要器官上其差异也具有统计学意义(P<0.01),调整等中心技术对肺组织保护得最好。结论:通过调整靶区等中心能够提高靶区剂量均匀性,有效降低重要器官的受量,提高乳腺癌的控制率,而且此法简单易行,值得推广。