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.

Uncertainties of ＂in v/vo＂ Dosimetry Using Semiconductors

The purpose of the present study is to evaluate the uncertainties of in vivo dosimetry measured with diode detectors for conformal radiation therapy techniques in order to define appropriate tolerance levels for pelvis and breast treatment in MEIH （Middle East Institute of Health）. The present work is carried out on 30-472 and 30-473 diode detectors irradiated by 4 and 15MV photon beams of a medical linear accelerator Synergy from ELEKTA. Dose computation is performed with Pinnacle 7.4 k treatment planning system. First, an estimation of the uncertainties in a simple geometric case, using a water-equivalent solid phantom is done. Secondly, each treatment parameter such as field size, beam angle, beam modifiers and source-skin distance is evaluated in order to simulate the conformal radiation treatments used in the present institution for the main anatomical sites. Interpretation of entrance dose in-vivo measurements requires the determination of appropriate tolerance levels. Indeed, the authors found that the 5% action level proposed in the literature underestimates the uncertainties in the treatment process. A method for the evaluation of tolerance/action levels related to the different anatomical sites is developed. By the end of the present study the authors have developed an integrated monitoring system that offers accurate information about the dose received by patients.

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.

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).

Comparison of Dosiology between Three Dimensional Conformal and Intensity-modulated Radiotherapies (5 and 7 fields) in Gastric Cancer Post-surgery

The purpose of this study was to compare the dose distribution of intensity-modulated ra- diotherapy （IMRT） in 7 and 5 fields as well as 3-D conformal radiotherapy （3D-CRT） plans for gastric cancer using dosimetric analysis. In 15 patients with gastric cancer after D1 resection, dosimetric pa- rameters for IMRT （7 and 5 fields） and 3D-CRT were calculated with a total dose of 45 Gy （1.8 Gy/day） These parameters included the conformal index （CI）, homogeneity index （HI）, maximum dose spot for the planned target volume （PTV）, dose-volume histogram （DVH） and dose distribution in the organs at risk （OAR）, mean dose （Dmean）, maximal dose （Dmax） in the spinal cord, percentage of the normal liver volume receiving more than 30 Gy （V30） and percentage of the normal kidney volume receiving more than 20 Gy （V20）. IMRT （7 and 5 fields） and 3D-CRT achieved the PTV coverage. However, IMRT presented significantly higher CI and HI values and lower maximum dose spot distribution than 3D-CRT （P=0.001）. For dose distribution of OAR, IMRT had a significantly lower Dmean and Dmax in spinal cord than 3D-CRT （P=-0.009）. There was no obvious difference in V30 of liver and V20 of kidney between IMRT and 3D-CRT, but 5-field IMRT showed lower Dmean in the normal liver than other two plans （P=0.001）. IMRT revealed favorable tumor coverage as compared to 3D-CRT and IMRT plans. Specifically, 5-field IMRT plan was superior to 3D-CRT in protecting the spinal cord and liver, but this superiority was not observed in the kidney. Further studies are needed to compare differences among the three approaches.

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.

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.

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.

食管癌三维适形放射治疗剂量学与放射性肺炎发生相互关系的研究

目的:通过食管癌常规放射治疗与三维适形放射治疗的技术对比研究,比较应用不同外照射技术时肿瘤靶区适形指数的差异,以及肺等正常组织受照射容积剂量与放射性肺炎并发症发生概率(NTCP)的关系。方法:应用三维治疗计划系统,对28例胸中段EPC分别设计三种照射技术(A:常规3野;B:适形3野;C:适形5野)。比较在同一处方剂量(66Gy)时肿瘤靶区的适形指数,全肺受照射剂量与肺的NTCP的差异。结果:A、B、C三种照射技术比较:1)靶区的适形指数从0.55±0.09提高至0.76±0.04和0.78±0.06。2)肺平均剂量从(16.54±2.35)Gy降低至(13.26±1.93)Gy和(3.38±1.61)Gy;肺的V20从(32.95±6.43)%降低至(23.01±6.25)%和(24.8±4.47)%;肺的V30从(17.25±4.96)%降低至(12.18±3.66)%和(6.75±2.93)%。3)肺的NTCP从(6.9±6.86)%降低至(1.14±1.11)%和(1±1.02)%。A、B和C三种照射技术比较差异均有统计学意义,P=0.000。结论:三维适形放射治疗技术的靶区剂量分布较理想,显著降低正常肺的照射体积和剂量,减少放射性肺炎NTCP。

鼻腔NK/T细胞淋巴瘤常规放疗与适形调强放疗的剂量学比较

目的比较分析3种不同放疗技术治疗鼻腔NK/T细胞淋巴瘤的剂量学差异,为临床治疗提供依据。方法选取6例鼻腔NK/T细胞淋巴瘤患者,应用三维治疗计划系统(TPS)分别为每例患者设计3种治疗计划,即常规放疗(CRT)、三维适形放疗(3D-CRT)和调强适形放疗(IMRT),对CRT要求参考点达到处方剂量54Gy,对3D-CRT和IMRT要求95%的等剂量线(54Gy)包括整个计划靶体积(PTV)。根据等剂量曲线及剂量体积直方图(DVH)比较3种计划靶区剂量分布及危及器官(OAR s)受量的差异。结果 3D-CRT及IMRT的靶区适形度指数(C I)、均匀性指数(H I)均较CRT计划好,同时减少了脑干、腮腺的受照射剂量;3D-CRT及IMRT的处方剂量覆盖靶区体积百分比高于CRT。结论对鼻腔NK/T细胞淋巴瘤,3D-CRT及IMRT可以提高靶区的适形度和均匀度,在保护脑干、腮腺方面较CRT具有明显优势,其中IMRT优势更明显。

胸上段食管癌调强放疗和三维适形放疗剂量学研究

目的:比较分析胸上段食管癌调强适形(IMRT)放疗和三维适形(3D-CRT)放疗的剂量学差异。方法:选择10例胸上段食管癌患者,应用三维治疗计划系统(TPS)分别为每例患者设计2种治疗计划(A:调强适形放疗;B:三维适形放疗),在规定PTV至少达到95%处方剂量前提下根据体积直方图(DVH)比较2种计划靶区剂量分布及脊髓、肺、心脏等正常组织受量的差异。结果:2种计划的靶区适形度指数(CI)、均匀性指数(HI)、处方剂量覆盖PTV百分比均以IM-RT计划为好,IMRT同时减少了脊髓最大所受剂量,差异均有统计学意义(P<0.05);2种计划的双肺受照剂量V20、心脏平均剂量均在可耐受的范围内,差异无统计学意义(P>0.05)。结论:胸上段食管癌采用IMRT优于3DCRT放疗,是目前较好的一种放疗方法。

CRT+ARC技术在肺癌“T”形靶区患者放射治疗中的剂量学研究

目的:探讨适形放疗(CRT)+容积旋转调强(ARC)在肺癌"T"形靶区放疗计划中的剂量学特点。方法:使用瓦里安计划系统(Eclipse 10.0)对随机选取的15例已行固定野调强放射治疗(FF-IMRT)治疗的肺癌"T"形靶区的患者,采用CRT和ARC设计CRT+ARC计划,采用CRT和FF-IMRT设计CRT+IMRT计划。在满足相同处方剂量要求的情况下,评价和比较两种治疗计划中计划靶区(PTV)的最小剂量(D_(min))、最大剂量(D_(max))、中位剂量、适形度指数(CI)、均匀性指数(HI)和危及器官受量(正常肺的V_5、V_(10)、V_(13)、V_(20)、V_(30)和平均剂量,脊髓D_(max),心脏V_(20)、V_(30)、V_(40)、V_(45)和平均剂量,食管V50、D_(max)),并比较两种治疗计划正常组织B-P受量和总机器跳数。结果:(1)PTV剂量学指标。CRT+ARC计划与CRT+IMRT计划相比,靶区中位值和V107略有升高,具有统计学意义(P=0.000、0.003),其它剂量学指标(PTV的D_(min)、D_(max)、CI、HI)均无统计学意义。(2)危及器官受量。CRT+ARC计划与CRT+IMRT计划相比,脊髓D_(max)有所降低,且具有统计学意义(P=0.000),正常肺的V13有所升高,但不具有统计学意义,正常肺的V_5、V_(10)、V_(20)、V_(30)和平均剂量有所降低,且V_(20)、V_(30)和平均值具有统计学意义(P=0.000、0.020、0.006);其它危及器官受量,食管V50和D_(max),心脏V_(20)、V_(30)、V_(40)、V_(45)和平均剂量,均无统计学意义。(3)正常组织B-P受量。CRT+ARC计划与CRT+IMRT计划相比,V10略有增高,且具有统计学意义(P=0.030);V_(15)、V_(20)、V_(25)和V_(30)有所降低,且具有统计学意义(P=0.000、0.000、0.000、0.001);其它剂量学指标(V_5、V_(35)、V_(40)、V_(45)和V_(50))无统计学意义。(4)机器跳数。CRT+ARC计划和CRT+IMRT计划单次计划中各射野机器跳数累加之和分别为460±59、1 561±180,两者有显著统计学意义(P=0.000)。结论:对于局部晚期或晚期具有"T"形(或"Y"形)靶区的肺癌患者,CRT+ARC计划比CRT+IMRT计划,在靶区剂量分布、保护肺和脊髓方面表现出了优势,明显减少了机器跳数,且肺和正常组织的低剂量受照体积受量未增加,还有一定程度的降低,这对于CRT+ARC技术在临床上应用,具有重要的指导意义。

三维适形放疗与调强放疗对上段食管癌中的疗效及剂量学分析

目的分析三维适形放疗与调强放疗对上段食管癌中的疗效与剂量学差异,为临床治疗提供参考。方法选取40例段食管癌患者为研究对象,随机分为适形组与调强组各20例,分别采用三维适形放疗与调强放疗。比较两组患者的疗效,各计划靶区计量学差异,重要器官受量及放疗相关并发症发生率。结果 1适形组总有效率为80.0%,调强组为85.0%,两组患者总有效率无显著性差异(P>0.05);适形组放射性肺炎和骨髓抑制发生率均显著高于调强组(P<0.05)。2GVT下三维适形放疗和调强放疗Dmean、Dmax无显著性差异,但调强放疗D95、D99高于三维适形放疗,而V105和HI均低于三维适形放疗;PTV1下两种放疗的Dmean、Dmax、D95、D99无显著性差异,但调强放疗V105和HI低于三维适形放疗,而CI高于三维适形放疗(P<0.05)。3但调强组脊髓Dmax,肺V10、V20、V30均显著低于适形组(P<0.05)。结论三维适形放疗与调强放疗对上段食管癌的有效率相近,但后者具有更好的剂量适形性,可脊髓、肺等重要器官照射剂量。

不同能量在胸中上段食管癌调强放疗中的剂量学对比研究

目的:研究在胸中上段食管癌调强计划(IMRT)设计中不同能量的X线对肿瘤计划靶区PTV及危及器官的影响,探寻更适合的能量。方法:选择42例胸中上段食管癌患者,采用Pinnacle38.0 m治疗计划系统,对每例患者分别采用6MVX线和10 MVX线两种能量,在相同布野方案和优化参数情况下分别进行IMRT计划设计并进行剂量学比较。比较的参数有:PTV的95%体积的剂量(D95)和5%体积的剂量(D5)、适形指数(CI)、均匀指数(HI)和脊髓的最大剂量(Dmax),双肺的500 cGy、1000 cGy、2000 cGy、3000 cGy剂量体积(V5,V10,V20,V30)和平均剂量(Dmean),心脏的平均剂量(Dmean)和3000 cGy、4000 cGy剂量体积(V30、V40)等。结果:在靶区剂量参数方面,6 MVX线计划组与10 MVX线计划组PTV的Dmean、HI、CI、D95、D5差异无统计学意义(P>0.05);对于危及器官,心脏的Dmean、V30,脊髓的Dmax,双肺的V20、V30差异有统计学意义(P<0.05);对于正常组织B-P的V20、V31.5差异有统计学意义(P<0.05)。结论:胸中上段食管癌调强计划中,采用10 MVX线计划组的调强计划与6 MVX线计划组的靶区剂量分布相似,但心脏、脊髓、肺和皮肤等危及器官的受照剂量较低。

晚期胰腺癌适形、简化调强及螺旋断层放疗的剂量学评估

目的:分析比较晚期胰腺癌三维适形放疗(3D-CRT)、简化调强放射治疗(s IMRT)和螺旋断层放疗(HT)的剂量学特点。方法:选择10例晚期胰腺癌腹膜后淋巴结转移患者,分别设计其3D-CRT、s IMRT和HT计划,比较其靶区及危及器官的所受剂量情况。结果:3D-CRT、s IMRT和HT计划平均适形指数分别为0.63、0.79和0.90;与3D-CRT相比较,s IMRT(P=0)、HT(P=0)均具有统计学差异;与s IMRT相比较,HT(P=0)亦存在统计学差异。对3D-CRT而言,s IMRT和HT在肝脏V5、V10等低剂量区均偏高,且三者之间均具有统计学差异(P=0.001,P=0.004);而V20、V30、V40、V50等高剂量区均偏低,且V30(P=0.002)、V50(P=0)均显示统计学差异。与s IMRT相比,HT中肝脏V5、V10、V20较高,而V30、V40、V50均较低,而其他危及器官中相对于3D-CRT,s IMRT和HT中左/右肾、小肠V5值较高,左/右肾、小肠及胃V20、V30、V40及V50值均较低;与s IMRT相比,HT中左/右肾、小肠V5、V20、V30、V40较低,而胃的V5、V10值则略高,然而其V20、V30、V40及V50均显较低。结论:与3D-CRT相比,晚期胰腺癌s IMRT和HT改善了剂量分布适形度,降低了肝脏、胃、小肠和左、右肾的高剂量区体积;与s IMRT比较,HT靶区剂量更均匀,肝脏等危及器官的高剂量区体积更低。本研究为临床治疗计划设计提供了重要的参考依据。

乳腺癌术后不同放疗技术的剂量学评价

目的：评价乳腺癌保乳术及根治术后调强放疗（IMRT）与适形放疗（3D－CRT）的剂量学特点。方法选取乳腺癌患者20例作为研究对象，其中保乳术患者10例，随机分为A、B两组，每组5例，根治术患者10例，随机分为C、D两组，每组5例。 A、C组均采用IMRT，B、D组均采用3D－CRT，分别比较4组患者的放射剂量学差异及优劣。结果①无论是保乳术后还是根治术后采用IMRT技术，计划靶区（ PTV）的HI、CI值均优于3D－CRT；②IMRT技术下，根治组双肺V5、V10、Dmean以及患侧肋骨Dmin低于保乳组，健侧乳腺Dmax大于保乳组；③应用3D－CRT技术，2组患者参数无统计学意义；④IMRT组患者各器官低剂量体积大于3D－CRT组，而高剂量体积小于3D－CRT组。以上差异均有统计学意义（P＜0．05）。结论乳腺癌术后行IMRT及3D－CRT均能较好地覆盖靶区，但IMRT的剂量均匀性、靶区适形度优于3D－CRT，3D－CRT对正常组织的等低剂量照射体积控制较好，而IMRT可以有效降低高剂量照射体积，均匀性更好。仅仅从计划参数上比较，乳腺癌术后调强放疗获益更大。

上段食管癌累及野照射CRT、3D-CRT与IMRT计划的剂量学对比研究

目的比较颈段、胸上段食管癌常规放疗(CRT)、三维适形放疗(3D-CRT)、调强放疗(IMRT)累及野放疗中靶区和危及器官(OAR)的剂量学差异,进而为临床治疗选择最优放射治疗方案;比较不同大小肿瘤(直径<3 cm及>5 cm)不同放疗计划对危及器官的影响,进而选择较优的放疗计划。方法选择12例颈段及胸上段食管癌患者,应用三维治疗计划系统(TPS)分别为每位患者设计三种治疗计划(A.常规放疗;B三维适形放疗;C调强适形放疗),在规定CTV至少达到95%处方剂量前提下根据剂量体积直方图(DVH)、等剂量曲线比较三种计划靶区剂量分布及脊髓、气管、肺正常组织受量的差异;同时比较不同大小的肿瘤三种放疗计划对脊髓的剂量学影响。结果三种计划的靶区的平均剂量以IMRT计划为好,IMRT同时减少了脊髓及气管的剂量,差异有统计学意义(P<0.05);不管肿瘤直径大小,以IMRT计划最好。结论颈段及胸上段食管癌采用调强适形放疗,能在提高靶区剂量的同时更好的保护周围正常组织及器官,较三维适形放疗有剂量学优势,是目前较好的一种放疗方法。

胸中段食管癌适形调强放疗和三维适形放疗方案的应用探讨

目的比较胸中段食管癌适形调强放疗(IMRT)和三维适形放疗(3D-CRT)两种不同技术中计划靶区(PTV)及正常组织的受量。方法对52例ⅡB-Ⅳ期胸中段食管癌患者用同一放疗计划系统分别设计IMRT和3D-CRT根治性放疗计划,应用剂量体积直方图(DVH)比较两种方法中计划靶区和正常组织受量并且计算计划靶区适形指数(CI)和剂量不均匀指数(HI)。结果 IMRT方法的PTV适形度优于3D-CRT;脊髓剂量的最大值低于3D-CRT,但无统计学差异;心脏接受V25和V40的体积百分比低于3D-CRT;IMRT显著降低了肺部V10和V20的有效体积,但其肺部的V5大于3D-CRT。结论在可接受的放射性损伤的基础上,IMRT技术较3D-CRT能够提高行根治性放疗的ⅡB-Ⅳ期胸中段食管癌患者靶区剂量,靶区适形度高,但可使肺组织受到更大容积的低剂量照射。