Impact of intensity-modulated radiotherapy on health-related quality of life for head and neck cancer patients: matched-pair comparison with conventional radiotherapy

PURPOSE: To assess the benefit of intensity-modulated radiotherapy (IMRT) compared with conventional RT for the quality of life (QOL) of head and neck cancer survivors. METHODS AND MATERIALS: Cross-sectional QOL measures (European Organization for Research and Treatment of Cancer QOL questionnaire C30 and head and neck cancer module) were used with a French multicenter cohort of patients cured of head and neck cancer (follow-up > or = 1 year) who had received bilateral neck RT (> or = 45 Gy) as a part of their initial treatment. We compared the QOL mean scores regarding RT modality (conventional RT vs. IMRT). The patients of the two groups were matched (one to one) according to the delay between the end of RT and the timing of the QOL evaluation and the T stage. Each QOL item was divided into two relevant levels of severity: "not severe" (responses, "not at all" and "a little") vs. "severe" (responses "quite a bit" and "very much"). The association between the type of RT and the prevalence of severe symptoms was approximated, through multivariate analysis using the prevalence odds ratio. RESULTS: Two comparable groups (67 pairs) were available. Better scores were observed on the head and neck cancer module QOL questionnaire for the IMRT group, especially for dry mouth and sticky saliva (p < 0.0001). Severe symptoms were more frequent with conventional RT concerning saliva modifications and oral discomfort. The adjusted prevalence odds ratios were 3.17 (p = 0.04) for dry mouth, 3.16 (p = 0.02) for sticky saliva, 3.58 (p = 0.02) for pain in the mouth, 3.35 (p = 0.04) for pain in the jaw, 2.60 (p = 0.02) for difficulties opening the mouth, 2.76 (p = 0.02) for difficulties with swallowing, and 2.68 (p = 0.03) for trouble with eating. CONCLUSION: The QOL assessment of head and neck cancer survivors demonstrated the benefit of IMRT, particularly in the areas of salivary dysfunction and oral discomfort.     

宫颈癌术后盆腔调强放疗计划方法的剂量学比较研究

目的 比较两种调强放疗(IMRT)方法 (对骨髓进行单独限最的BMS-IMRT,未对骨髓进行单独限量的IMRT)在宫颁癌靶体积剂量覆盖及危及器官保护方面的差异,探讨宫颈癌患者术后盆腔外照射骨髓保护的合理方法 .方法 对10例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.进而设计出BMS-IMRT和IMRT的2种治疗计划,处方剂量为45 Gy分25次,1.8 Gy/次.所有计划都使95%靶区体积达到处方剂量要求.并用ADAC Pinnacle~3计划系统提供的卷积或迭加算法对两种放疗技术的治疗计划进行剂量计算,比较靶区及危及器官剂量分布、剂量体积直方图参数.结果 BMS-IMRT计划的靶区剂量均匀性不如IMRT,但其适形度优于IMRT计划,BMS-IMRT放疗计划中骨髓的V_5、V_(10)、V_(20)、V_(30)、V_(40)分别比IMRT降低1.81%、8.61%、31.81%、29.50%、28.29%,而小肠、膀胱、直肠等危及器官的受量差别不大.结论 对于宫颈癌术后患者BMS-IMRT降低了骨髓低剂量受照体积,从而有助于降低急性骨髓抑制发生概率、提高患者生活质量,值得在临床工作中推广应用.     

调强和常规放疗对头颈部癌患者生存质量影响评估

目的 前瞻性评估调强和常规放疗对头颈部癌患者生存质量(QOL)的影响和差异以指导临床.方法 2007-2008年102例头颈部癌患者(口腔癌76例,口咽癌14例,鼻咽癌11例,颈部转移癌1例)在上海第九人民医院放疗科接受放疗,其中IMRT组52例,至少保护一侧腮腺,其中24例加对侧颌下腺保护;常规放疗组50例,不保护唾液腺.采用EORTC QLQ-C30和头颈部癌HN35通用量表,在放疗前,放疗结束日,放疗后2、6个月对患者QOL中33个领域进行评估,以10分以上的得分变化为有临床意义.结果 调强和常规放疗造成头颈部癌患者QOL 94%(31/33)领域下降,其中49%(16/33)显著下降(U=2.72～5.98,P值均<0.01),33%(11/33)的下降有临床意义;放疗后2个月有12%(4/33)领域出现有临床意义的恢复,但15%(5/33)领域尚未恢复(U=3.10～5.93,P值均<0.01);放疗后6个月QOL继续改善,有21%(7/33)领域出现有统计学和临床意义的恢复,并优于放疗前,但在口干和唾液粘稠症状2个领域尚未恢复(U=4.49、4.87,P<0.01、0.01).IMRT对口干和唾液粘稠领域的影响比常规放疗明显小(U=4.57、5.57,P值均<0.01),并在放疗后持续改善,常规放疗未见改善,组间有非常显著性差异(U=7.23、7.57,P值均<0.01).结论 放疗造成头颈部癌患者QOL显著下降,放疗后出现持续性恢复,但口干和唾液粘稠症状恢复差,是影响QOL的主要原因.IMRT优点是对口干和唾液粘稠症状影响明显小于常规放疗,对保存QOL意义重大.     

Clinical outcome in posthysterectomy cervical cancer patients treated with concurrent Cisplatin and intensity-modulated pelvic radiotherapy: comparison with conventional radiotherapy

PURPOSE: To assess local control and acute and chronic toxicity with intensity-modulated radiation therapy (IMRT) as adjuvant treatment of cervical cancer. METHODS AND MATERIALS: Between April 2002 and February 2006, 68 patients at high risk of cervical cancer after hysterectomy were treated with adjuvant pelvic radiotherapy and concurrent chemotherapy. Adjuvant chemotherapy consisted of cisplatin (50 mg/m(2)) for six cycles every week. Thirty-three patients received adjuvant radiotherapy by IMRT. Before the IMRT series was initiated, 35 other patients underwent conventional four-field radiotherapy (Box-RT). The two groups did not differ significantly in respect of clinicopathologic and treatment factors. RESULTS: IMRT provided compatible local tumor control compared with Box-RT. The actuarial 1-year locoregional control for patients in the IMRT and Box-RT groups was 93% and 94%, respectively. IMRT was well tolerated, with significant reduction in acute gastrointestinal (GI) and genitourinary (GU) toxicities compared with the Box-RT group (GI 36 vs. 80%, p = 0.00012; GU 30 vs. 60%, p = 0.022). Furthermore, the IMRT group had lower rates of chronic GI and GU toxicities than the Box-RT patients (GI 6 vs. 34%, p = 0.002; GU 9 vs. 23%, p = 0.231). CONCLUSION: Our results suggest that IMRT significantly improved the tolerance to adjuvant chemoradiotherapy with compatible locoregional control compared with conventional Box-RT. However, longer follow-up and more patients are needed to confirm the benefits of IMRT.     

A comparison of conformal and intensity-modulated techniques for oesophageal radiotherapy.

BACKGROUND AND PURPOSE: To investigate the potential of intensity-modulated radiotherapy (IMRT) to reduce lung irradiation in the treatment of oesophageal carcinoma with radical radiotherapy. MATERIALS AND METHODS: A treatment planning study was performed to compare two-phase conformal radiotherapy (CFRT) with IMRT in five patients. The CFRT plans consisted of anterior, posterior and bilateral posterior oblique fields, while the IMRT plans consisted of either nine equispaced fields (9F), or four fields (4F) with orientations equal to the CFRT plans. IMRT plans with seven, five or three equispaced fields were also investigated in one patient. Treatment plans were compared using dose-volume histograms and normal tissue complication probabilities. RESULTS: The 9F IMRT plan was unable to improve on the homogeneity of dose to the planning target volume (PTV), compared with the CFRT plan (dose range, 16.9+/-4.5 (1 SD) vs. 12.4+/-3.9%; P=0.06). Similarly, the 9F IMRT plan was unable to reduce the mean lung dose (11.7+/-3.2 vs. 11.0+/-2.9 Gy; P=0.2). Similar results were obtained for seven, five and three equispaced fields in the single patient studied. The 4F IMRT plan provided comparable PTV dose homogeneity with the CFRT plan (11.8+/-3.3 vs. 12.4+/-3.9%; P=0.6), with reduced mean lung dose (9.5+/-2.3 vs 11.0+/-2.9 Gy; P=0.001). CONCLUSIONS: IMRT using nine equispaced fields provided no improvement over CFRT. This was because the larger number of fields in the IMRT plan distributed a low dose over the entire lung. In contrast, IMRT using four fields equal to the CFRT fields offered an improvement in lung sparing. Thus, IMRT with a few carefully chosen field directions may lead to a modest reduction in pneumonitis, or allow tumour dose escalation within the currently accepted lung toxicity.     

Patterns of local-regional recurrence following parotid-sparing conformal and segmental intensity-modulated radiotherapy for head and neck cancer

Purpose: To analyze the patterns of local-regional recurrence in patients with head and neck cancer treated with parotid-sparing conformal and segmental intensity-modulated radiotherapy (IMRT).

Methods and Materials: Fifty-eight patients with head and neck cancer were treated with bilateral neck radiation (RT) using conformal or segmental IMRT techniques, while sparing a substantial portion of one parotid gland. The targets for CT-based RT planning included the gross tumor volume (GTV) (primary tumor and lymph node metastases) and the clinical target volume (CTV) (postoperative tumor bed, expansions of the GTVs and lymph node groups at risk of subclinical disease). Lymph node targets at risk of subclinical disease included the bilateral jugulodigastric and lower jugular lymph nodes, bilateral retropharyngeal lymph nodes at risk, and high jugular nodes at the base of skull in the side of the neck at highest risk (containing clinical neck metastases and/or ipsilateral to the primary tumor). The CTVs were expanded by 5 mm to yield planning target volumes (PTVs). Planning goals included coverage of all PTVs (with a minimum of 95% of the prescribed dose) and sparing of a substantial portion of the parotid gland in the side of the neck at less risk. The median RT doses to the gross tumor, the operative bed, and the subclinical disease PTVs were 70.4 Gy, 61.2 Gy, and 50.4 Gy respectively. All recurrences were defined on CT scans obtained at the time of recurrence, transferred to the pretreatment CT dataset used for RT planning, and analyzed using dose–volume histograms. The recurrences were classified as 1) “in-field,” in which 95% or more of the recurrence volume (V_recur) was within the 95% isodose; 2) “marginal,” in which 20% to 95% of V_recur was within the 95% isodose; or 3) “outside,” in which less than 20% of V_recur was within the 95% isodose.

Results: With a median follow-up of 27 months (range 6 to 60 months), 10 regional recurrences, 5 local recurrences (including one noninvasive recurrence) and 1 stomal recurrence were seen in 12 patients, for a 2-year actuarial local-regional control rate of 79% (95% confidence interval 68–90%). Ten patients (80%) relapsed in-field (in areas of previous gross tumor in nine patients), and two patients developed marginal recurrences in the side of the neck at highest risk (one in the high retropharyngeal nodes/base of skull and one in the submandibular nodes). Four regional recurrences extended superior to the jugulodigastric node, in the high jugular and retropharyngeal nodes near the base of skull of the side of the neck at highest risk. Three of these were in-field, in areas that had received the dose intended for subclinical disease. No recurrences were seen in the nodes superior to the jugulodigastric nodes in the side of the neck at less risk, where RT was partially spared.

Conclusions: The majority of local-regional recurrences after conformal and segmental IMRT were “in-field,” in areas judged to be at high risk at the time of RT planning, including the GTV, the operative bed, and the first echelon nodes. These findings motivate studies of dose escalation to the highest risk regions.     

Comparison of intensity-modulated radiotherapy with conventional conformal radiotherapy for complex-shaped tumors

Purpose: Conformal and intensity-modulated radiotherapy (IMRT) plans for 9 patients were compared based on characterization of plan quality and effects on the oncology department.

Methods and Materials: These clinical cases, treated originally with conformal radiotherapy (CRT), required extraordinary effort to produce conformal treatment plans using nonmodulated, shaped noncoplanar fields with multileaf collimators (MLCs). IMRT plans created for comparison included rotational treatments with slit collimator, and fixed-field MLC treatments using equispaced coplanar, and noncoplanar fields. Plans were compared based upon target coverage, target conformality, dose homogeneity, monitor units (MU), user-interactive planning time, and treatment delivery time. The results were subjected to a statistical analysis.

Results: IMRT increased target coverage an average of 36% and conformality by 10%. Where dose escalation was a goal, IMRT increased mean dose by 4–6 Gy and target coverage by 19% with the same degree of conformality. Rotational IMRT was slightly superior to fixed-field IMRT. All IMRT techniques increased integral dose and target dose heterogeneity. IMRT planning times were significantly less, whereas MU increased significantly; estimated delivery times were similar.

Conclusion: IMRT techniques increase dose and target coverage while continuing to spare organs-at-risk, and can be delivered in a time frame comparable to other sophisticated techniques.     

直肠癌五野调强放疗与传统适形放疗剂量学研究

Objective  

The aim of the study was to compare the difference of dose distribution in clinical target volume and organ at risk (OAR) between five-field intensity-modulated radiotherapy (IMRT) and conventional three-dimensional conformal radiotherapy (3DCRT) in the radiotherapy of rectal cancer.     

自动和逆向3DCRT与逆向IMRT计划剂量学比较

目的 比较自动3DCRT、逆向3DCRT、逆向IMRT计划的剂量学差异。方法 选取2014—2015年间单一靶区肺癌10例和颅内肿瘤10例,经网络传输至RayStation4.5TPS。采用自动3DCRT、逆向3DCRT和逆向IMRT方法分别对20例病例进行治疗计划设计,3种PTV和OAR剂量体积限制条件一致、射野数相同,比较3种计划的等剂量分布、靶区和OAR剂量参数。采用多相关变量和双相关变量分布分析。结果 肺癌病例中IMRT计划D_98%、D_50%、D_2%、CI和HI均优于逆向3DCRT和自动3DCRT计划(P=0.007、0.001、0.002、0.000、0.000);自动3DCRT计划的CI优于逆向3DCRT计划(P=0.000),3种计划中心脏D₃₃、脊髓D_max和D_{1 cm³}、双肺的各参数受量均相近(P=0.702、0.237、0.163、0.739、0.908、0.832、0.886、0.722、0.429、0.840、0.702);颅内肿瘤病例中逆向IMRT和自动3DCRT计划的CI优于逆向3DCRT计划(P=0.002、0.034),其他靶区参数相近(P=0.648、0.783、0.256、0.931),3种计划全脑受量各参数相近(P=0.446、0.755、0.772、0.0266、0.440、0.290、0.939)。结论 单一靶区肺癌和颅内肿瘤病例中,与逆向3DCRT技术相比,自动3DCRT技术可提高靶区CI;与逆向IMRT技术相比,对OAR保护相近,考虑到3DCRT的简便性和低成本,自动3DCRT技术可以作为一种新放疗技术进行推广。     

老年食管癌患者三维适形或调强放疗疗效及预后

目的:分析70岁以上老年食管癌患者对单纯三维适形放射治疗(3DCRT)或调强放射治疗(IMRT)技术的耐受性和近远期疗效.方法: 回顾分析53例未手术仅单纯放疗的食管癌患者,年龄70-94岁,中位74岁,46例患者合并内科疾病.临床分期T1-4,均无远处转移.采用三维适形放射治疗(3DCRT)和调强放射治疗(IMRT)技术,靶区剂量范围26.1-72.9Gy,单次剂量1.8-2.2Gy.95%的计划靶区满足处方剂量.生存率采用Kaplan-Meier,组间生存率比较采用Log rank检验,组间率的比较采用χ2检验.结果:88.7%的患者完成治疗剂量,88.2% 完全缓解(CR),2年总生存率(OS)、癌症相关生存率(CSS)分别为 37.4%和48.2%.与CR相关因素包括有无内科合并症、疗前血红蛋白(Hb)、肿瘤体积(GTV)、ECOG评分、T分期、有无淋巴结转移和放疗剂量.单因素分析与OS和CSS均相关的因素包括疗前Hb、ECOG评分和近期疗效,而内科合并症、GTV体积与OS相关,内科合并症中仅有无慢阻肺与CSS相关.多因素分析与二者相关的仅疗前Hb、近期疗效.结论:因内科疾病不能手术老年患者,单纯3DCRT或IMRT放疗耐受性好,近远期疗效好.影响总生存率的独立预后因素主要是完全缓解率和疗前Hb.     

胸上段食管癌调强放疗与适形放疗计划的剂量学比较

背景与目的：胸上段食管癌所处的解剖特点导致其放疗计划的制订难度很大,而调强放疗（intensity-modulated radiotherapy,IMRT）有可能克服上述难题。本研究比较分析IMRT和三维适形放疗（conformal radiotherapy,CRT）在胸上段食管癌的剂量学优劣,为IMRT在食管癌的临床应用提供参考。方法：选择胸上段食管癌11例进行研究。在实际治疗采用的CRT计划基础上,每一病例再设计-5野IMRT计划进行对比。对比内容包括相关靶区和危及器官的剂量体积直方图参数。结果：肿瘤及相邻组织的计划靶区可见IMRT和CRT计划之间的平均剂量、最大剂量、包含99％和95％靶区的剂量均很接近（P〉0．05）,但IMRT较CRT的适形指数好（0．68±0．04vs．0．46±0．11,P〈0．01）。IMRT对锁骨上区的剂量均匀性较CRT更好,二者的非均匀指数分别为1．17±0．05和1．33±0．15（P=0．01）。IMRT计划中脊髓计划区的最高受量明显较CRT的低（44．4Gyvs．52．5Gy,P〈0．05）：10Gy以上的肺受照体积为（32±6）％．也明显较CRT计划的（35±9）％低（P〈0．05）。结论：对胸上段食管癌,调强放疗较适形放疗有更好的剂量适形性,可更有效保护脊髓,并显著降低肺10Gy以上剂量的受照体积。     

Clinical application of intensity-modulated radiotherapy for head and neck cancer

Intensity-modulated radiotherapy (IMRT) is a modern treatment technique that allows one to shape the dose to the target volume and to reduce the dose delivered to healthy tissue. Over the last decade, IMRT has been implemented for head and neck cancer treatment, with the aim of reducing the dose delivered to the parotid glands and improving the dose coverage of complex target volumes located close to critical structures. The potential benefits of IMRT in terms of salivary function preservation and better local control have contributed to the rapid diffusion of this new technology. However, it should not be overlooked that IMRT is a novel treatment technique and that its clinical application represents a paradigm shift in the practice of radiation oncology. The purpose of this article is to review the clinical experience with IMRT for head and neck cancer treatment and to discuss some important issues related to its implementation.     

胸上段食管癌3DCRT与IMRT的剂量学比较

目的：比较胸上段食管癌三维适形放射治疗（3D-CRT）与调强放射治疗（IMRT）放疗剂量学的差异,为临床医师选择放疗方案提供参考。方法收集25例胸上段食管癌病例（临床分期为Ⅰ～Ⅲ期）,应用Oncentra三维放射治疗计划系统分别对每一位患者的靶区进行3D-CRT和IMRT治疗计划设计,拟定95％PTV处方剂量为60 Gy。通过剂量体积直方图（ DVH）参数,对95％等剂量线所包括的PTV体积百分比（V95）、靶区适形度指数（CI）、剂量不均匀指数（HI）和危及器官所受照射剂量进行对比分析。结果 IMRT和3D-CRT两种不同放疗计划：V95分别为（99．91±0．14）％、（95．73±4．14）％,差异有统计学意义（P＜0．05）;靶区最大剂量Dmax分别为（6658．26±215．29）cGy、（6664．20±465．16）cGy,差异没有统计学意义（P＞0．05）;靶区最小剂量Dmin分别为（5458．88±184．06）cGy、（4541．60±599．0）cGy,差异有统计学意义（P＜0．05）;靶区平均剂量Dmean分别为（6232．80±53．00）cGy、（6105．78±163．34） cGy,差异有统计学意义（P＜0．05）;CI值分别为（0．76±0．04）、（0．57±0．05）,差异有统计学意义（P＜0．05）;HI值分别为1．07±0．02、1．12±0．06,差异有统计学意义（P ＜0．05）;脊髓最大剂量分别为（3889．68±712．69）cGy、（4337．48±178．49）cGy,差异有统计学意义（P＜0．05）;双肺V20分别为（20．94±5．32）％、（21．90±6．94）％,差异没有统计学意义（P＞0．05）;双肺V10分别为（35．39±11．41）％、（29．0±8．80）％,差异有统计学意义（P＜0．05）,双肺V5分别为（44．95±15．55）％、（37．27±11．93）％,差异有统计学意义（ P＜0．05）。结论调强放疗在胸上段食管癌治疗中显示出95％等剂量线所包括的PTV体积、靶区适形度及靶区内平均剂量、脊髓保护方面均优于3D-CRT技术;但是双肺低剂量照射区域有所增加,肺损伤的风险就有可能增大。     

Optimisation of radiotherapy for carcinoma of the parotid gland: a comparison of conventional, three-dimensional conformal, and intensity-modulated techniques.

BACKGROUND AND PURPOSE: To compare external beam radiotherapy techniques for parotid gland tumours using conventional radiotherapy (RT), three-dimensional conformal radiotherapy (3DCRT), and intensity-modulated radiotherapy (IMRT). To optimise the IMRT techniques, and to produce an IMRT class solution. MATERIALS AND METHODS: The planning target volume (PTV), contra-lateral parotid gland, oral cavity, brain-stem, brain and cochlea were outlined on CT planning scans of six patients with parotid gland tumours. Optimised conventional RT and 3DCRT plans were created and compared with inverse-planned IMRT dose distributions using dose-volume histograms. The aim was to reduce the radiation dose to organs at risk and improve the PTV dose distribution. A beam-direction optimisation algorithm was used to improve the dose distribution of the IMRT plans, and a class solution for parotid gland IMRT was investigated. RESULTS: 3DCRT plans produced an equivalent PTV irradiation and reduced the dose to the cochlea, oral cavity, brain, and other normal tissues compared with conventional RT. IMRT further reduced the radiation dose to the cochlea and oral cavity compared with 3DCRT. For nine- and seven-field IMRT techniques, there was an increase in low-dose radiation to non-target tissue and the contra-lateral parotid gland. IMRT plans produced using three to five optimised intensity-modulated beam directions maintained the advantages of the more complex IMRT plans, and reduced the contra-lateral parotid gland dose to acceptable levels. Three- and four-field non-coplanar beam arrangements increased the volume of brain irradiated, and increased PTV dose inhomogeneity. A four-field class solution consisting of paired ipsilateral coplanar anterior and posterior oblique beams (15, 45, 145 and 170 degrees from the anterior plane) was developed which maintained the benefits without the complexity of individual patient optimisation. CONCLUSIONS: For patients with parotid gland tumours, reduction in the radiation dose to critical normal tissues was demonstrated with 3DCRT compared with conventional RT. IMRT produced a further reduction in the dose to the cochlea and oral cavity. With nine and seven fields, the dose to the contra-lateral parotid gland was increased, but this was avoided by optimisation of the beam directions. The benefits of IMRT were maintained with three or four fields when the beam angles were optimised, but were also achieved using a four-field class solution. Clinical trials are required to confirm the clinical benefits of these improved dose distributions.     

Comparison of dose contribution to normal pelvic tissues among conventional, conformal and intensity-modulated radiotherapy techniques in prostate cancer

High-energy external radiotherapy has become one of the most common treatment in localized prostate cancer. We compared the difference of dose distribution, mainly at the 5-30 Gy dose level, in the irradiated pelvic volume among three modalities of radiotherapy for patients with prostate cancer: conventional, conformal and intensity-modulated radiotherapy (IMRT). We selected six patients with prostate cancer treated by conformal radiotherapy at the doses of 46 Gy to PTVN (prostate and seminal vesicles), and 70 Gy to PTV-T (prostate). The conventional technique": an 8-field arrangement was used; the conformal technique 4 fields with a boost through 6 fields. For IMRT, a five-beam arrangement was used. Dose-volume histograms (DVH) were analyzed and compared among the three techniques. The IMRT technique significantly increased the pelvic volume covered by the isodose surfaces below 15 Gy as compared with the conventional and conformal techniques. The mean absolute increase for the pelvic volume included between 5-30 Gy for the IMRT technique, was about 2 900 ml as compared with the conventional technique. However, IMRT significantly reduced the irradiated volume of the rectum in the dose range of 5 to 40 Gy, also significantly reduced the irradiated volume of bladder and femoral heads, and obtained a similar or improved isodose distribution in the PTVs. In addition, the use of IMRT slightly increased the relative dose delivered to the body volume outside the pelvis, as estimated by the use of specific software. A long-term follow-up will be needed to evaluate potential late treatment complications related to the use of IMRT and the low or moderate irradiation dose level obtained in the pelvis and in the whole body.     

Dosimetric comparison of bone marrow-sparing intensity-modulated radiotherapy versus conventional techniques for treatment of cervical cancer

PURPOSE: To compare bone marrow-sparing intensity-modulated pelvic radiotherapy (BMS-IMRT) with conventional (four-field box and anteroposterior-posteroanterior [AP-PA]) techniques in the treatment of cervical cancer. METHODS AND MATERIALS: The data from 7 cervical cancer patients treated with concurrent chemotherapy and IMRT without BMS were analyzed and compared with data using four-field box and AP-PA techniques. All plans were normalized to cover the planning target volume with the 99% isodose line. The clinical target volume consisted of the pelvic and presacral lymph nodes, uterus and cervix, upper vagina, and parametrial tissue. Normal tissues included bowel, bladder, and pelvic bone marrow (PBM), which comprised the lumbosacral spine and ilium and the ischium, pubis, and proximal femora (lower pelvis bone marrow). Dose-volume histograms for the planning target volume and normal tissues were compared for BMS-IMRT vs. four-field box and AP-PA plans. RESULTS: BMS-IMRT was superior to the four-field box technique in reducing the dose to the PBM, small bowel, rectum, and bladder. Compared with AP-PA plans, BMS-IMRT reduced the PBM volume receiving a dose >16.4 Gy. BMS-IMRT reduced the volume of ilium, lower pelvis bone marrow, and bowel receiving a dose >27.7, >18.7, and >21.1 Gy, respectively, but increased dose below these thresholds compared with the AP-PA plans. BMS-IMRT reduced the volume of lumbosacral spine bone marrow, rectum, small bowel, and bladder at all dose levels in all 7 patients. CONCLUSION: BMS-IMRT reduced irradiation of PBM compared with the four-field box technique. Compared with the AP-PA technique, BMS-IMRT reduced lumbosacral spine bone marrow irradiation and reduced the volume of PBM irradiated to high doses. Therefore BMS-IMRT might reduce acute hematologic toxicity compared with conventional techniques.     

肺癌三维适形及调强放疗诱导肺损伤与剂量体积直方图参数的相关性

目的 探讨肺癌三维适形放疗（3D-CRT）和调强放疗（IMRT）诱导肺损伤（RILI）与剂量体积直方图（DVH）参数的关系及两种放疗计划的差异。方法 151例肺癌患者分别接受3D-CRT（n=90）和IMRT（n=61）,均给予根治性放疗剂量,采用传统分割照射（1.8～2.0Gy／次,1次／天,5次／周）,中位剂量60.0Gy。比较两组发生RILI的差异,并分析两组发生≥2级RILI与DVH参数的关系。结果 3D-CRT组≥2级RILI发生率为17.8％,略低于IMRT组的24.6％;≥3级RILI发生率为8.9％,略高于IMRT组的3.3％,差异无统计学意义（P＞0.05）。单因素分析显示,3D-CRT组V20可增加≥2级RILI的发生风险（OR=3.780,P=0.030）;IMRT组V5、V10、V13、V20和平均照射剂量均可增加≥2级RILI的发生风险（OR：3.575～6.286,P：0.003～0.045）。多因素分析显示V20是RILI的独立危险因素。结论 3D-CRT和IMRT对肺癌患者≥2级RILI的发生率影响不明显,但RILI的发生风险均与V20相关。     

Target coverage for head and neck cancers treated with IMRT: review of clinical experiences

The use of intensity-modulated radiation (IMRT) for the treatment of head and neck cancers is less than a decade old, and long-term clinical results both with regards to tumor outcome and late radiation toxicity are still lacking. Despite this limitation, the use of IMRT is gaining popularity. Preliminary clinical experiences have been encouraging, suggesting that the 2 goals of IMRT for treatment of head and neck cancer can be achieved. These goals are improved tumor coverage reflected in high rates of disease control and a decrease of toxicity. The availability of IMRT has forced head and neck radiation oncologists to both rethink old practices as well as potentially introduce new therapeutic paradigms. This review will focus on how IMRT is being implemented into the treatment of head and neck cancer, specifically with regards to target definition and dosing issues.