Dosimetric evaluation of an ipsilateral intensity modulated radiotherapy beam arrangement for parotid malignancies

Background

We conducted a dosimetric comparison of an ipsilateral beam arrangement for intensity modulated radiotherapy (IMRT) with off-axis beams.

Patients and methods

Six patients who received post-operative radiotherapy (RT) for parotid malignancies were used in this dosimetric study. Four treatment plans were created for each CT data set (24 plans): 1) ipsilateral 4-field off-axis IMRT (4fld-OA), 2) conventional wedge pair (WP), 3) 7 field co-planar IMRT (7fld), and 4) ipsilateral co-planar 4-field quartet IMRT (4fld-CP). Dose, volume statistics for the planning target volumes (PTVs) and planning risk volumes (PRVs) were compared for the four treatment techniques.

Results

Wedge pair plans inadequately covered the deep aspect of the PTV. The 7-field IMRT plans delivered the largest low dose volumes to normal tissues. Mean dose to the contralateral parotid was highest for 7 field IMRT. Mean dose to the contralateral submandibular gland was highest for 7 field IMRT and WP. 7 field IMRT plans had the highest dose to the oral cavity. The mean doses to the brainstem, spinal cord, ipsilateral temporal lobe, cerrebellum and ipsilateral cochlea were similar among the four techniques.

Conclusions

For postoperative treatment of the parotid bed, 4-field ipsilateral IMRT techniques provided excellent coverage while maximally sparing the contralateral parotid gland and submandibular gland.     

Dose Planning Study of Target Volume Coverage with Intensity-Modulated Radiotherapy for Nasopharyngeal Carcinoma: Penang General Hospital Experience

Background: To compare the dosimetric coverage of target volumes and organs at risk in the radicaltreatment of nasopharyngeal carcinoma (NPC) between intensity-modulated radiotherapy (IMRT) and threedimensionalconformal radiotherapy (3DCRT). Materials and Methods: Data from 10 consecutive patientstreated with IMRT from June-October 2011 in Penang General Hospital were collected retrospectively foranalysis. For each patient, dose volume histograms were generated for both the IMRT and 3DCRT plans usinga total dose of 70Gy. Comparison of the plans was accomplished by comparing the target volume coverage (5measures) and sparing of organs at risk (17 organs) for each patient using both IMRT and 3DCRT. The meansof each comparison target volume coverage measures and organs at risk measures were obtained and testedfor statistical significance using the paired Student t-test. Results: All 5 measures for target volume coverageshowed marked dosimetric superiority of IMRT over 3DCRT. V70 and V66.5 for PTV70 showed an absoluteimprovement of 39.3% and 24.1% respectively. V59.4 and V56.4 for PTV59.4 showed advantages of 18.4% and16.4%. Moreover, the mean PTV70 dose revealed a 5.1 Gy higher dose with IMRT. Only 4 out of 17 organsat risk showed statistically significant difference in their means which were clinically meaningful between theIMRT and 3DCRT techniques. IMRT was superior in sparing the spinal cord (less 5.8Gy), V30 of right parotid(less 14.3%) and V30 of the left parotid (less 13.1%). The V55 of the left cochlea was lower with 3DCRT (less44.3%). Conclusions: IMRT is superior to 3DCRT due to its dosimetric advantage in target volume coveragewhile delivering acceptable doses to organs at risk. A total dose of 70Gy with IMRT should be considered as astandard of care for radical treatment of NPC.     

Improvements in target coverage and reduced spinal cord irradiation using intensity-modulated radiotherapy (IMRT) in patients with carcinoma of the thyroid gland.

BACKGROUND AND PURPOSE: External beam radiotherapy for thyroid carcinoma poses a significant technical challenge as the target volume lies close to or surrounds the spinal cord. The potential of intensity-modulated radiotherapy (IMRT) to improve the dose distributions was investigated. MATERIALS AND METHODS: A planning study was performed on patients with thyroid carcinoma. Plans were generated to irradiate the thyroid bed alone or to treat the thyroid bed and the loco-regional lymph nodes in two phases. Conventional plans with minimal beam shaping were compared to three-dimensional conformal radiotherapy (3DCRT) and inverse-planned IMRT plans to assess target coverage and normal tissue sparing. IMRT techniques were optimized to find the minimum number of equispaced beams required to achieve the clinical benefit and a concomitant boost technique was explored. RESULTS: For the thyroid bed alone and the thyroid bed plus loco-regional lymph nodes, conventional and conformal techniques produced low minimum doses to the planning target volume (PTV) if spinal cord tolerance was respected. 3DCRT reduced the irradiated volume of normal tissue (P=0.01). IMRT plans achieved the goal dose to the PTV (P<0.01) and also reduced the spinal cord maximum dose (P<0.01). IMRT, using a concomitant boost technique, produced better target coverage than a two-phase technique. For both the two-phase and concomitant boost techniques, IMRT plans with seven and five equispaced fields produced similar dose distributions to nine fields, but three fields were significantly worse. CONCLUSIONS: 3DCRT reduced normal tissue irradiation compared to conventional techniques, but did not improve PTV or spinal cord doses. IMRT improved the PTV coverage and reduced the spinal cord dose. A simultaneous integrated boost technique with five equispaced fields produced the best dose distribution. IMRT should reduce the risk of myelopathy or may allow dose escalation in patients with thyroid cancer.     

髓母细胞瘤不同放疗技术剂量学研究

目的 比较髓母细胞瘤常规加速器不同三维放疗技术与断层治疗计划的剂量分布。
方法 2011年12例髓母细胞瘤患者在CT模拟分段扫描后图像耦合,分别进行7个野三维适形放疗(3DCRT)、9和13个野调强放疗(IMRT)计划[全脑全脊髓(PTV)36 Gy,后颅窝加量至54 Gy],对PTV、危及器官剂量参数进行分析并与国外断层治疗计划比较。
结果 3DCRT需设置3个中心,而IMRT只要2个中心。PTV剂量分布9个野IMRT好于3DCRT、13个野IMRT,靶区均匀性指数分别为0.93、0.82、0.89(F=6.17,P=0.02),靶区适形指数分别为0.97、 0.88、0.95(F=5.23,P=0.01)。9个野IMRT与断层治疗的剂量分布类似。
结论 常规加速器全脑全脊髓9个野IMRT可达断层治疗剂量分布且简便易行。     

子宫颈癌术后盆腔转移三维适形与调强放疗剂量学对比研究

目的 比较三维适形放疗(3DCRT)和调强放疗(IMRT)在子宫颈癌术后盆腔转移病灶靶区(PTY)剂量覆盖和危及器官(OAR)保护方面的差异,探讨子宫颈癌术后盆腔转移病灶的最佳治疗方案.方法 选择10例子宫颈癌根治术后盆腔转移患者,行CT模拟定位后将数据上传至Varian三维计划系统,勾画靶区,进行放疗计划设计后做下列研究:3DCRT计划与IMRT计划对计划靶区PTV的影响及比较;3DCRT计划与IMRT计划中危及器官受最比较分析.结果 采用95%可信区间,CTV至PTV的外放边界定为1 cm.3DCRT计划中3、4、5和6个射野下PTV适形指数分别为0.46、0.67、0.68、0.68,4个以上射野数日的增加不再显著改善靶区分布和减少正常组织受照射体积百分比.IMRT计划中5、7、9、11和13个射野下PTV适形指数分别为0.75、0.83、0.84、0.85、0.85,9个以上射野数目增加不再显著改善靶区分布和减少正常组织受照体积百分比.比较OAR最高照射剂量,IMRT计划中小肠脊髓的最高照射剂量低于3DCRT,直肠膀胱及股骨头的最大剂量差异无统计学意义.结论 子宫颈癌术后盆腔转移放疗者3DCRT以4个射野数计划为优,IMRT以9个射野数计划为优.高剂量范围内IMRT较3DCRT对脊髓及小肠的保护作用明显,IMRT较3DCRT减少了高剂量区直肠、膀胱的受照体积,从而有望减少OAR放射治疗并发症的发生概率.

Abstract：

Objective To compare the differences of target-volume(PTV) coverage and organ at risk (OAR) protection between three dimensional conformal radiotherapy (3DCRT) and intensity-modulated radiotherapy(IMRT) for patients with pelvis metastasis of cervical cancer underwent radical hysterectomy and pelvic lymphadenectomy. To explore the optimal treatment methods for pelvis metastasis of cervical cancer.Methods 10 patients with pelvis metastasis of cervical cancer underwent radical hysterectomy and pelvic lymphadenectomy were selected for this study. The images scanned by CT were transferred to treatment planning system to generate 3DCRT and IMRT plans. The impacts of 3DCRT on PTV were compared with those of IMRT. Isodose line and dose volume histograms(DVH) were used to evaluate to the dose-distribution in PTV and OAR. Results For 95 % confidence interval, the margin from CTV to PTV was 1 cm. Conformal indexs (CIs) of PTV for 3, 4, 5 and 6 fields 3DCRT were 0.46, 0.67, 0.68 and 0.68, respectively. When beyond 4 fields, the advantage of adding fields was not significant. CIs of PTV for 5, 7, 9, 11 and 13 fields IMRT were 0.75, 0.83 0.84, 0.85 and 0.85, respectively. When beyond 9 fields, the advantage of adding fields was not significant. The maximum dose of the bowl and spine cord in IMRT plans were lower than that in the 3DCRT plans (P <0.05). Maximum dose of OAR had no significant differences (includingt the bone, recttum and bladder) between IMRT and 3DCRT plans. Conclusion For patients with pelvis metastasis of cervical cancer after radical surgery, 4 fields planning in 3DCRT and 9 fields planning in IMRT are feasible. At high dose levels, the IMRT plans can more significantly protect the bowl and spine cord and decrease the radiation volume of colorectal and urinary bladder at risk than 3DCRT, so IMRT may potentially diminish probability of the normal tissue complications.     

Beam-orientation optimization of intensity-modulated radiotherapy: clinical application to parotid gland tumours.

BACKGROUND AND PURPOSE: An optimization algorithm has been developed to determine the best beam-arrangement for a small number of intensity-modulated radiotherapy (IMRT) fields. The algorithm is designed to avoid, if possible, beam-orientations that pass through organs-at-risk (OARs) with low radiation tolerance. MATERIALS AND METHODS: An independent, fast IMRT algorithm based on the Bortfeld algorithm was developed to determine the profile of the intensity-modulated beams (IMBs) for each beam-arrangement and a fast-simulated-annealing algorithm finds the 'optimal' beam-arrangement. The final beam-arrangement was transferred to the CORVUS (NOMOS Corporation) treatment planning system, and the IMBs were re-optimized for comparison with a standard nine-field, equi-spaced arrangement. The algorithm has been initially tested on a single example patient, with a parotid gland carcinoma. RESULTS: The nine-field, IMRT plan for an example patient with a parotid gland tumour significantly reduced the dose to the cochlea compared with the conformal radiotherapy plan. In addition, the planning-target-volume (PTV) homogeneity was improved, but the plan produced a higher dose to the contralateral parotid (73% of the OAR received more than 6 Gy). The beam-orientation optimization algorithm produced a three-field plan that greatly reduced the dose to the contralateral parotid (maximum dose of 2 Gy), whilst maintaining the PTV dose homogeneity and the reduced cochlear dose of the nine-field plan. Some changes in the dose to the other OARs, namely the brain and the oral cavity, were seen, but were deemed not to be clinically significant. CONCLUSIONS: In conclusion, IMB-orientation optimization for head and neck treatment sites can produce improvements in treatment plans with only a few fields.     

三维适形与调强放疗技术在胃癌术后放疗中的剂量学比较

目的比较胃癌放疗中三维适形放疗(3DCRT)和调强放疗(IMRT)技术的剂量学差异,为临床应用提供参考。方法采用3DCRT治疗的5例胃癌术后患者,放疗时使用了主动呼吸门控技术,以减少呼吸引起的器官运动。IMRT计划采用7个共面等间距野,仅用于剂量学比较。患者靶区设定的处方剂量为至少95%计划靶体积(PTV)接受45.00 Gy,至少99%PTV接受42.75 Gy。根据积分剂量体积直方图(DVH)比较PTV受量和相关正常器官的受量差异和剂量分布。结果与IMRT相比3DCRT的剂量均匀性和适形度略差,但两者在PTV受量上剂量相似。对左、右肾受15 Gy剂量的体积百分比(V_(15))而言,3DCRT好于IMRT;从正常肝的平均受量及V_(30)上看,IMRT稍优于优势;在脊髓的受量上两者相似。结论3DCRT技术在主动呼吸门控辅助下,PTV和部分正常器官的受量上可接近或者达到采用相等野数的IMRT的结果。     

Organ-sparing Intensity-modulated Radiotherapy for Anal Cancer using the ACTII Schedule: A Comparison of Conventional and Intensity-modulated Radiotherapy Plans

AimsConventional external beam radiotherapy for anal cancer is associated with a high rate of treatment-related morbidity. The purpose of this retrospective study was to compare the dosimetric advantages of three intensity-modulated radiotherapy (IMRT) plans with the conventional plan with regards to organs at risk avoidance delivering the ACTII schedule of 50.4 Gy in 1.8 Gy/fraction: 17 fractions for phase 1 and 11 fractions for phase 2.Materials and methodsTen anal cancer patients (T1-3 N0-3) treated with the conventional plan using four fields and conformal boost were identified. The phase 1 planning target volume (PTV) included tumour, anal canal and inguinal, peri-rectal and internal/external iliac nodes. Phase 2 included identifiable disease only. Three step-and-shoot IMRT plans were generated: IMRT1: phase 1 inverse-planned IMRT with two- to four-field conformal phase 2; IMRT2: both phase 1 and phase 2 inverse-planned IMRT; IMRT3: phase 1 IMRT and phase 2 forward-planned IMRT. All IMRT plans were then compared against the conventional plan on PTV coverage, small bowel, genitalia, femoral heads, bladder and healthy tissue dose volume information.ResultsWhile achieving similar PTV coverage compared with the conventional plan, significant dose reductions were observed for IMRT plans in external genitalia, small bowel and healthy tissue. Reductions were also observed in the femoral heads and bladder.ConclusionsIMRT significantly reduces the dose to organs at risk while maintaining excellent PTV coverage in anal cancer radiotherapy.     

子宫颈癌术后盆腔不同体外照射方法的剂量学研究

目的 比较常规放疗(CRT)、三维适形放疗(3DCRT)及调强放疗(IMRT)方法在子宫颈癌靶体积剂量覆盖及危及器官(OAR)保护方面的差异,探讨子宫颈癌患者术后盆腔体外照射的合理方法.方法 对10例子宫颈癌术后患者进行模拟CT增强扫描,在计划系统内勾画临床靶体积(CTV),CTV均匀外扩1.0 cm生成计划靶体积(PTV),同时勾画小肠、直肠、膀胱、骨髓、卵巢及股骨头作为OAR.进而设计出CRT、3DCRT及IMRT的3种治疗计划,对CRT要求参考点达到处方剂量45 Gy,对3DCRT及IMRT要求95%的PTV达45 Gy.应用等剂量曲线及剂量体积直方图对3种计划的CTV及OAR的剂量分布进行比较.结果 CRT计划中CTV达45 Gy的平均体积显著低于3DCRT、IMRT计划(Q=8.27、8.37,P值均＜0.01),而3DCRT和IMRT计划之间相似(Q=0.10,P＞0.05).3DCRT和IMRT计划中小肠达30、45 Gy的体积明显低于CRT.IMRT计划中直肠、膀胱达30、45 Gy的体积均显著低于CRT,而3DCRT中仅直肠、膀胱达45 Gy的体积显著低于CRT.3DCRT和IMRT使骨髓达30、45 Gy剂量的体积明显低于CRT.4例卵巢移位者中2例在3DCRT及IMRT计划中,另2例在3种计划中卵巢平均受量全部超过300 cGy.结论 IMRT和3DCRT在提高靶体积内剂量及其均匀度,以及保护小肠、直肠和膀胱方面较CRT具备明显优势,以IMRT为最佳.在高剂量范围内,IMRT和3DCRT对骨髓的保护优势确定.对于移位悬吊的卵巢,IMRT、3DCRT及CRT均不能对其形成有效保护.     

胸中段食管癌三维适形放疗、调强放疗及旋转调强放疗的剂量学研究

 目的　研究胸中段食管癌三维适形放疗（3DCRT）、调强放疗（IMRT）、旋转调强放疗（IMAT）3种放疗计划的剂量差异。方法　选取胸中段食管癌患者15例,以Varian Eclipse 8.6计划系统分别设计3DCRT、IMRT、IMAT 3种放疗计划,其中3DCRT采用5～8个共面射野,IMRT采用7个共面射野,IMAT采用2个弧度。比较3种计划的剂量学差异。结果　IMRT、IMRT的靶区均匀指数（HI）、适形指数（CI）、95 % 计划靶体积（PTV）体积剂量均优于3DCRT,全肺V5、V20、V35、心脏V30受照剂量低于3DCRT（t＝2.531,P＜0.05）,而在全肺V10、V15、V25、V30、全肺平均、心脏平均、脊髓Dmax剂量之间三者的差异均无统计学意义（t＝1.325,P＞0.05）。结论　IMAT与IMRT在胸中段食管癌放疗靶区体积剂量覆盖和危及器官保护方面相似,二者均优于3DCRT。IMAT的机器跳数和照射时间均少于IMRT。     

三维适形放疗与调强放疗在不同肺叶非小细胞肺癌中的剂量学研究

目的 比较不同肺叶非小细胞肺癌(NSCLC)的调强放疗(IMRT)和三维适形放疗(3DCRT)的剂量学特点.方法 以肿瘤位于上叶(上叶组)及下叶(下叶组)的各10例接受根治性放疗的NSCLC患者为研究对象,分别制定5野IMRT计划及3～5野3DCRT计划,应用剂量体积直方图评估两组治疗计划,分别比较上叶组、下叶组IMR...     

颈段、胸上段食管癌３ＤＣＲＴ／ＩＭＲＴ剂量学比较

目的　通过对颈段、胸上段食管癌三维适形（３ＤＣＲＴ）和调强（ＩＭＲＴ）放疗计划的剂量学比较,选择符合临床要求的最优方案。方法　１４例颈段、胸上段食管癌患者模拟定位后参考食管钡餐和内镜检查结果勾画ＧＴＶ,按照统一标准确定ＣＴＶ、ＰＴＶ,分别设计３ＤＣＲＴ、５野均匀分布ＩＭＲＴ-Ａ和５野非均匀分布ＩＭＲＴ-Ｂ共３套放疗计划,以９５％ＰＴＶ获得１００％处方剂量进行归一,分析各计划靶区剂量分布及危及器官受量的差异。结果　本组病例所有的ＩＭＲＴ计划均能满足治疗要求,而４例３ＤＣＲＴ计划不能满足要求,本研究仅对１０组可行计划进行进一步的剂量学比较。预防照射区（ＰＴＶ１）：３ＤＣＲＴ计划的剂量参数Ｄ_ｍｅａｎ、Ｄ_１００、Ｄ_９５分别为（５７２５±５４.９６）ｃＧｙ、（４７０３±２５.２６）ｃＧｙ、（５２０３±７１.７０）ｃＧｙ,明显高于ＩＭＲＴ-Ａ的（５３４８±２７.１４）ｃＧｙ、（４１５８±２７.３６）ｃＧｙ、（４９９６±５４.７４）ｃＧｙ和ＩＭＲＴ-Ｂ的（５２３２±２６.８５）ｃＧｙ、（４２８６±１２.１３）ｃＧｙ、（４９７９±３１.７８）ｃＧｙ（Ｐ＜０.０５）;３ＤＣＲＴＶ１０５为（８２.９５±３.０２）％,高于ＩＭＲＴ-Ａ的（７１.０７±６.６８）％和ＩＭＲＴ-Ｂ的（６９.５５±４.５６）％（Ｐ＜０.０５）,Ｖ１００、Ｖ９５无明显差异（Ｐ＞００５）。肿瘤区（ＰＴＶ２）：３套放疗计划的Ｄ_ｍｅａｎ、Ｄ_１００、Ｄ_９５、Ｖ_１０５、Ｖ_９５无明显差异（Ｐ＞０.０５）,而ＩＭＲＴ-Ａ和ＩＭＲＴ-Ｂ的Ｖ_１００分别为（９５.２１±１.７８）％和（９６.１２±２.５５）％,均高于３ＤＣＲＴ的（８８.６９±１.８４）％（Ｐ＜０.０５）;ＩＭＲＴ-Ａ和ＩＭＲＴ-ＢＨＩ分别为１.０８±０.０１和１.０２±０.０１,低于３ＤＣＲＴ的１.１８±０.０３,差异有统计学意义（Ｐ＜０.０５）。除肺Ｖ５外,ＩＭＲＴ-Ａ和ＩＭＲＴ-Ｂ脊髓Ｄ_ｍａｘ、肺Ｖ_２０、Ｖ_３０、ＭＬＤ分别为（３６４１±２３.４１）ｃＧｙ、（２２.０８±０.３１）％、（１１.０７±０.５１）％、（１０３４±３７.５１）ｃＧｙ和（３３０３±７５.３９）ｃＧｙ、（１９.８２±１.７４）％、（１０.１４±１.２０）％、（９８１±３８.１６）ｃＧｙ,均小于３ＤＣＲＴ的（４１１３±３８.２８）ｃＧｙ、（２８.０７±６.３０）％、（１９.７２±５.２６）％、（１３５６±３８.９１）ｃＧｙ,差异具有统计学意义（Ｐ＜０.０５）。ＩＭＲＴ计划剂量参数、体积参数、剂量分布均匀性无明显差别（Ｐ＞０.０５）;ＩＭＲＴ-Ｂ肺ＭＬＤ和脊髓Ｄｍａｘ较ＩＭＲＴ-Ａ低,差异具有统计学意义（Ｐ＜０.０５）。结论　颈段、胸上段食管癌放疗采用ＩＭＲＴ优于３ＤＣＲＴ,根据靶区形状非均匀布野ＩＭＲＴ可进一步降低肺和脊髓受照剂量。     

日本京都大学前列腺癌三个外放疗计划比较

[目的]比较分析日本京都大学医院对局限性前列腺癌实施治疗的三个外放疗计划。[方法]从放疗计划数据库中调取5例局限性前列腺癌的定位CT影像资料，分别按先前的三维适形计划（old 3DCRT）、新的3DCRT（new 3DCRT）和调强放疗计划（IMRT）做计划，根据剂量体积直方图比较各计划剂量分布的差异。[结果]临床靶区（CTV，即前列腺）的剂量覆盖在三个计划中都基本相似并达到理想的剂量分布，但对于计划靶区（PTV），V95、D95和适形指数值在IMRT分别为99％、97％和0．88；在new 3DCRT为93．9％、94．5％和0．76；在old 3DCRT为59．6％、82．9％和0．6。在IMRT计划中PTV的剂量不均整值较new 3DCRT计划中的高；直肠壁接受大于40Gy剂量的体积百分数在IMRT和new 3DCRT中差异不大，在old 3DCRT中最低。[结论]局限性前列腺癌动态弧三维适形放疗计划可以实现和调强放疗计划相比拟的靶区覆盖及对直肠壁的保护，尽管调强放疗计划可以达到更适形的靶区剂量分布，但代价是更高的剂量不均整。先前的三维适形计划达不到目前对PTV靶区的充分覆盖。     

简化调强技术应用于直肠癌术后放疗的剂量学比较

目的 评价直肠癌根治术后不同照射技术的靶区和正常组织剂量分布特点,为临床治疗方法的优选提供依据.方法 对10例男性、Ⅱ-Ⅲ期直肠癌经腹前切除(Dixon手术)术后患者分别进行t维适形放疗(3DCRT)、简化调强放疗(sIMRT)和调强放疗(IMRT)的计划设计,利用剂量体积直方图评价小同照射技术对靶Ⅸ和正常组织照射剂量、适形指数和小均匀指数.处方剂晕为50Gy.结果 靶区适形指数IMRT>sIMRT>3DCRT,靶区剂量不均匀指数3DCRT>sIMRT>IMRT.对危及器官保护sIMRT和IMRT优于3DCRT计划.sIMRT的子野跳数与3DCRT技术相当,但显著低于IMRT计划.3个野3DCRT、5个野3DCRT、5个野sIMRT、5个野IMRT和7个野IMRT的子野跳数平均值分别为482±13、504±11、455±42、841±36和884±46.结论 与3DCRT、IMRT计划相比sIM-RT计划具最优的时效比.此处方剂量水平下3种技术均能较好保护残端直肠和肛管.     

三维适形放疗与调强放疗在不同肺叶非小细胞肺癌中的刘量学研究

目的比较不同肺叶非小细胞肺癌（NSCLC）的调强放疗（IMRT）和三维适形放疗（3DCRT）的剂量学特点。方法以肿瘤位于上叶（上叶组）及下叶（下叶组）的各10例接受根治性放疗的NSCLC患者为研究对象,分别制定5野IMRT计划及3—5野3DCRT计划,应用剂量体积直方图评估两组治疗计划,分别比较上叶组、下叶组IMRT与3DCRT计划之间的剂量学参数。结果1）上叶组、下叶组的IMRT计划的以下指标优于相应的3DCRT计划,差异均有统计学意义（P〈0．05）：PTV参数、适形指数、异质性指数、平均肺剂量及肺V10～V65、食管Dmean及V55、心脏V40、食管的早晚期正常组织并发症发生率;2）IMRT计划比3DCRT计划平均降低了上叶组约2．7％的肺V5值及下叶组约1．1％的V5值,但差异无统计学意义（P〉0．05）;3）与3DCRT计划比较,上叶组、下叶组的IMRT计划的食管V35、心脏Dmean均较低,在上叶组的差异有统计学意义（P〈0．05）,在下叶组的差异无统计学意义（P〉0．05）。结论在NSCLC的根治性放疗中,5野IMRT较3DCRT更能提高靶区的剂量分布均匀性,在保护正常组织器官方面也显示出较明显的优势;且IMRT应用于上叶NSCLC的优势有可能大于下叶者。     

子宫颈癌术后调强放疗和三维适形放疗的临床疗效观察

目的 探讨子宫颈癌术后调强放疗（IMRT）与三维适形放疗（3DCRT）的临床疗效及安全性。方法 选取我院2012年9月至2013年3月60例宫颈癌术后患者,均制定IMRT和3DCRT两种放疗计划,随机分为IMRT组和3DCRT组进行放疗, IMRT组行5野6MV X射线放疗, 3DCRT组行4野6MV-X射线盒式照射,处方剂量均为95％计划靶区体积（PTV）为45 Gy／25 f／5 W。评价PTV和危及器官（OAR）的剂量分布特点;随访两组OAR的急慢性放射性损伤,计算两组3年生存率。结果IMRT组PTV的适形度指数（CI）、均匀性指数（HI）分别为0.80±0.03、1.10±0.01,3DCRT组分别为0.58±0.19、1.09±0.01,差异有统计学意义（P＜0.05）;IMRT组膀胱前壁的V10、V20、V30、V40和V45均低于3DCRT组,差异有统计学意义（P＜0.05）;IMRT组直肠后壁的V20、V30、V40和V45均低于3DCRT组,差异有统计学意义（P＜0.05）;IMRT组直肠和膀胱的急性和慢性放射性损伤发生率低于3DCRT组,差异有统计学意义（P＜0.05）。IMRT组3年生存率为83.3％,3DCRT组为80.0％,差异无统计学意义（P＞0.05）。结论 在PTV的CI、HI及保护OAR如膀胱前壁、直肠后壁上,IMRT优于3DCRT。