晚期肺癌非共面和共面IMRT剂量学比较研究

目的 比较研究晚期肺癌非共面IMRT计划剂量学分布特点,并观察计划执行安全性。方法 对14例晚期肺癌患者优化设计共面和非共面5、7个野IMRT计划,对比共面、非共面各组内及组间计划优化结果。观察4例患者非共面7个野计划的执行过程。结果 随射野数目增加共面及非共面靶区CI均改善(P值均为0.000),非共面野靶区D_mean、D_max、V_95%、HI亦有改善(P=0.001、0.001、0.009、0.000);共面野全肺、患、健肺V₅增加(P=0.000、0.002、0.000)及全肺D_mean增加(P=0.000),相反非共面野全肺、健肺V₅降低(P=0.001、0.005)。组间非共面7个野较共面5个野计划靶区各指标均改善(P值均为0.000);各肺V₂₀均降低(P值均为0.000)且全肺D_mean、V₃₀及健肺V₅降低(P=0.000、0.001、0.000),脊髓D_max亦有减少(P=0.033);但患肺V₅及心脏D_mean增加(P=0.000、0.003)。较共面7个野计划患肺V₅及心脏D_mean亦增加(P=0.000、0.048),但全肺及健肺V₅均降低(所有P=0.000)。4例患者均顺利完成非共面IMRT,全程未发生碰撞风险。结论 非共面7个野IMRT计划改善了靶区剂量分布,降低肺V₂₀、D_mean也控制了低剂量肺体积增加趋势且临床实施安全有效,值得推荐。     

Intensity-modulated radiotherapy technique for three-field breast treatment

PURPOSE: To develop a simplified intensity-modulated radiotherapy (IMRT) algorithm for three-field breast treatment using a single isocenter setup. The algorithm aims to deliver a uniform dose throughout the breast volume. Special attention was paid to the highly divergent nature of the beam configuration. METHODS AND MATERIALS: Computed tomography (CT) image setup of the patient was acquired. On each CT slice, the computer automatically generated lines parallel to the posterior edge of the tangent field. The mid-point of each line segment that intersected the breast was determined and the dose from an open field calculated. The intensity of the divergent pencil beam corresponding to the mid-point was set to be inversely proportional to the open field dose to the mid-point. Forward dose calculation was then performed using this intensity distribution. RESULTS: A total of 15 breast cancer patients undergoing three-field IMRT who underwent planning and treatment with this algorithm were included in this study. Compared with standard wedged pair tangents, the IMRT plan produced statistically significant better dose distributions in terms of target coverage and target dose uniformity, as well as reduced dose to the contralateral breast and reduced hot spots to the ipsilateral lung. CONCLUSION: Since March 2004, the new IMRT algorithm has been used for planning and treatment of > 20 patients undergoing three-field treatment, as well as >200 patients undergoing regular two-field tangent treatment, all with excellent dose distributions throughout the breast volume.     

非共面放疗技术的实现方式

非共面放疗是采用多个非共面固定野或者多个非共面弧照射的放疗技术。非共面射野是各个照射野的射野中心轴不在同一平面内,而非共面弧是指每个弧形成的轨迹不在同一个平面内。与共面放疗相比,非共面放疗技术实现立体多角度或多弧度的照射,提高了射线聚焦程度,有利于拉开靶区和周围正常组织受量;其剂量学优势已在多种肿瘤上得到证实,如颅内肿...     

Treatment planning evaluation of non-coplanar techniques for conformal radiotherapy of the prostate.

BACKGROUND AND PURPOSE: To evaluate the benefit of using non-coplanar treatment plans for irradiation of two different clinical treatment volumes: prostate only (PO) and the prostate plus seminal vesicles (PSV). MATERIAL AND METHODS: An inverse planning algorithm was used to produce three-field, four-field, five-field and six-field non-coplanar treatment plans without intensity-modulation in ten patients. These were compared against a three-field coplanar plan. A dose of 74 Gy was prescribed to the isocentre. Plans were compared using the minimum dose to the planning target volume (PTV), maximum dose to the small bowel, and irradiated volumes of rectum, bladder and femoral head. Biological indices were also evaluated. RESULTS: For the PO group, volume of rectum irradiated to 60 Gy (V(60)) was 22.5+/-3.7% for the coplanar plan, and 21.5+/-5.3% for the five-field non-coplanar plan, which was the most beneficial (p=0.3). For the PSV group, the five-field non-coplanar plan was again the most beneficial. Rectal V(60) was in this case reduced from 41.5+/-10.4% for the coplanar plan to 35.2+/-9.3% for the non-coplanar plan (p=0.02). CONCLUSIONS: The use of non-coplanar beams in conformal prostate radiotherapy provides a small increase in rectal sparing, more significantly with PSV volumes than for PO volumes.     

A treatment planning study using non-coplanar static fields and coplanar arcs for whole breast radiotherapy of patients with concave geometry.

PURPOSE: A treatment planning study was performed to evaluate the performance of new radiotherapy techniques based on non-coplanar multiple fields or on dynamic conformal arcs for early stage breast treatments. METHODS AND MATERIALS: CT datasets of 7 different patients that were deemed unsuitable for tangential beam treatment due to a large volume of lung in the treatment fields were used as input for the study. Standard tangential field plans and inversely modulated IMRT plans were used as benchmark to evaluate performances of conformal plans with 3 non-coplanar fields (3F-NC), with 2 short dynamic conformal arcs (2-Arc) or hybrid plans with one static conformal field and one dynamic conformal arc (P-Arc). All plans were designed to achieve the higher target coverage and minimum ipsilateral lung involvement depending on the planning technique with a key objective to avoid involvement of the contralateral breast. The following planning objectives were selected. For PTV: D(1%) (maximum significant dose) lower than 110% and D(99%) (minimum significant dose) higher than 90%. For the ipsilateral lung a mean dose lower than 15 Gy and/or a volume receiving more than 20 Gy lower than 22%. For contralateral breast, all techniques but IMRT were set to have no beam impinging this organ at risk, while for IMRT plans were further designed to keep the mean dose lower than 5 Gy and to minimise the volume receiving a dose higher than 70% of the prescribed dose. RESULTS: P-Arc resulted to be on average a better technique, as it provides a PTV dose distribution highly conformal (Conformity index 1.45), homogeneous (D(5%)-D(95%)=15.6%), with adequate coverage (V(90%)=96.4%) and a limited involvement of the ipsilateral lung (MLD approximately 9 Gy, V(5 Gy) approximately 36%, NTCP<2%) when compared to four other treatment techniques. 3F-NC presented similar but slightly worse performances on target: Conformity index 1.57, D(5%)-D(95%)=18.1%, V(90%)=95.7%). 3F-NC on ipsilateral lung resulted as the P-Arc. The tangential approach, the 2-Arc or the IMRT techniques, resulted to be inferior to the previous in either conformality (tangentials), ipsilateral lung sparing (tangentials, 2-Arc and IMRT) and in contralateral or healthy tissue involvement (IMRT). CONCLUSION: For early stage breast cancer when high sparing of lung tissues is required and no involvement of contralateral breast is allowed, the P-Arc or the 3F-NC techniques might be recommended in terms of dosimetric expectations.     

Dosimetric analysis of a simplified intensity modulation technique for prone breast radiotherapy

PURPOSE: Prone-position breast radiotherapy (RT) has been described as an alternative technique to improve dose homogeneity for women with large, pendulous breasts. We report the feasibility and dosimetric analysis of a simplified intensity-modulated RT (IMRT) technique, previously reported for women in the supine treatment position, to plan prone-position RT to the intact breast. METHODS AND MATERIALS: Twenty patients with clinical Stage TisN0-T1bN1 breast cancer undergoing breast-conserving therapy underwent whole breast RT using a prone position technique. The treatment plans were developed using both conventional tangents and a simplified intensity-modulated tangential beam technique based on optimization of the intensity distributions across the breast. The plans were compared with regard to the dose-volume parameters. RESULTS: Dose heterogeneity within the breast planning target volume was significantly greater for the conventional tangent plans. Of 20 patients, 16 (80%) received maximal doses of > or =110% using the conventional tangents vs. only 1 (5%) using the IMRT plan. The isodose level encompassing 5% of the planning target volume was reduced from an average of 110% with conventional tangents to 105% with IMRT. The maximal dose within the planning target volume was reduced from an average of 114% with conventional tangents to 107% with IMRT. The greatest improvement was seen in the patients with the most pendulous breasts. CONCLUSION: An IMRT planning approach is feasible for prone-position breast RT and improves dose homogeneity, particularly in women with larger, pendulous breasts. Additional follow-up is necessary to determine whether the improvements in dose homogeneity impact acute toxicity and cosmetic outcome in this cohort of women who have historically suffered from poor cosmesis after breast-conserving therapy.     

非共面IMRT在宫颈癌放疗计划中保护卵巢的可行性探讨

目的:探讨非共面IMRT在宫颈癌放疗计划中保护卵巢的可行性。方法:选取17例保卵巢宫颈癌放疗病例,按统一标准分别设计两组IMRT计划:共面IMRT保卵巢组(A组)和非共面IMRT保卵巢组（B组）;收集两组计划评估参数,并验证两组计划γ通过率,并进行统计学分析。结果:两组计划均满足临床要求。B组的卵巢最大受量小于A组（P＜0.05）。对于计划靶区,B组计划的适形指数、均匀指数优于A组计划（P＜0.05）,A组D5高于B组（P＜0.05）,B组D95高于A组（P＜0.05）。对于危及器官,A组在膀胱的V40、直肠的Dmean、小肠的Dmax、左侧股骨头的V20大于B组（P＜0.05）。A组和B组在膀胱的V20、V30、Dmean,直肠的V30、V40,小肠的V40,右侧股骨头的V10、V20、V30,左侧股骨头的V10、V30和骨髓的Dmax上均无明显差异（P＞0.05）。A组的总跳数小于B组（P＜0.05）;在3%/2 mm,低剂量阈值10%的标准下,A组γ通过率高于B组（P＜0.05）。结论:两种计划均能实现对卵巢的保护,非共面IMRT计划表现更佳,靶区剂量分布更优,对危及器官影响更小。     

CT-Sim技术在乳腺癌放射治疗中的应用

用大恒STAR 2 0 0 0三维放射治疗系统、GE双螺旋CT、国产北医BJ 6B型加速器对乳腺癌患者实施精确定位、虚拟计划设计、射野间无缝连接照射 ,可提高患者重复摆位的精度 ,定位时间短 ,射野间衔接好 ,患者皮肤反应轻 ,放射性肺炎发生率明显下降。     

Dynamic intensity-modulated non-coplanar arc radiotherapy (INCA) for head and neck cancer.

BACKGROUND AND PURPOSE: To define the potential advantages of intensity-modulated radiotherapy (IMRT) applied using a non-coplanar dynamic arc technique for the treatment of head and neck cancer. MATERIALS AND METHODS: External beam radiotherapy (EBRT) was planned in ten patients with head and neck cancer using coplanar IMRT and non-coplanar arc techniques, termed intensity modulated non-coplanar arc EBRT (INCA). Planning target volumes (PTV1) of first order covered the gross tumor volume and surrounding clinical target volume treated with 68-70 Gy, whereas PTV2 covered the elective lymph nodes with 54-55 Gy using a simultaneous internal boost. Treatment plan comparison between IMRT and INCA was carried out using dose-volume histogram and "equivalent uniform dose" (EUD). RESULTS: INCA resulted in better dose coverage and homogeneity of the PTV1, PTV2, and reduced dose delivered to most of the organs at risk (OAR). For the parotid glands, a reduction of the mean dose of 2.9 (+/- 2.0) Gy was observed (p = 0.002), the mean dose to the larynx was reduced by 6.9 (+/- 2.9) Gy (p = 0.003), the oral mucosa by 2.4 (+/- 1.1) Gy (p < 0.001), and the maximal dose to the spinal cord by 3.2 (+/- 1.7) Gy (p = 0.004). The mean dose to the brain was increased by 3.0 (+/- 1.4) Gy (p = 0.002) and the mean lung dose increased by 0.2 (+/- 0.4) Gy (p = 0.87). The EUD suggested better avoidance of the OAR, except for the lung, and better coverage and dose uniformity were achieved with INCA compared to IMRT. CONCLUSION: Dose delivery accuracy with IMRT using a non-coplanar dynamic arc beam geometry potentially improves treatment of head and neck cancer.     

Held-breath self-gating technique for radiotherapy of non-small-cell lung cancer: a feasibility study

PURPOSE: To examine the feasibility of a held-breath self-gating (HBSG) technique in the radiotherapy of lung cancer. MATERIAL AND METHODS: Sixteen consecutive eligible and consenting patients undergoing radiotherapy for non-small-cell lung cancer were accrued for this study. The patients underwent a standardized training session and were then asked to breath hold at four points in the breathing cycle (maximal and end tidal, inspiration and expiration) while under fluoroscopic visualization. Plain films and video imaging with digital image analysis were used to record and measure the movement of the diaphragm, a tumor surrogate, in the superior-inferior axis. These measurements were obtained during and between multiple separate breath holds within one session and between breath holds in sessions held at least one day apart. RESULTS: Maximal inspiration and expiration tend to provide the best positional reliability, and the standard deviation of diaphragmatic position ranged from 0.13 to 2.57 mm, with an average of 0.97 mm. During a single breath hold, the diaphragmatic movement averaged 2.62 mm with a standard deviation of 1.28 mm. The day-to-day variation of diaphragmatic positions was less than 5 mm. The held-breath self-gating technique resulted in a reduction of diaphragmatic movement by an average of 11.9 mm when compared to that seen during tidal breathing. CONCLUSION: In the radiotherapeutic management of non-small-cell lung cancer, this HBSG technique offers a simple method that provides superior immobilization of the diaphragm compared to tidal breathing. Clinical implementation of this technique should allow for a reduction of treatment margins, thus sparing more normal tissues and facilitating dose escalation.     

Effectiveness of virtual reality simulation software in radiotherapy treatment planning involving non-coplanar beams with partial breast irradiation as a model

We aimed to compare dosimetric characteristics of conventional linear accerator-based treatment plans to those created using the robotic CyberKnife(r) (CK) treatment planning system for patients with early-stage lung cancer. Eight early-stage lung cancer patients treated with stereotactic body radiotherapy (SBRT) using a conventional linac-based (LIN) system were included in this study. New treatment plans were created for the patients with the CK treatment planning system in order to compare the two platforms' dosimetric characteristics. Planning computed tomographies (CT) were obtained in three phases: free-breathing, full exhalation and inhalation. The three GTVs were then added together for internal target volume (ITV) with LIN, whereas no ITV was used for CK. Planning target volumes (PTV) were constituted by adding 5-mm margin to GTV and ITV. Treatment plan was 54?Gy in three fractions. Five-field, seven-field, and dynamic-conformal arc planning techniques were used in LIN plans. Plans were compared according to dose heterogenity (D(max)-maximum dose), volume of 54?Gy (V54) and 27?Gy isodose (V27), conformity index (CI(54) and CI(27)) and lung volumes. PTVs were significantly smaller in CK plans (p?5?0.012). D(max) was significantly lower in ARC plans (p?5?0.01). Among all plans, CK had significantly tightest isodose shell received 54?Gy and 27?Gy (p?5?0.0001). Among LIN plans, V54 was significantly (p?5?0.03) smaller in ARC plans; but no difference was observed for V27 values. LIN plans have better plan quality (CI(27) and CI(54)) than CK. No statistically significant difference was observed for lung volumes. CK plans had superior V54 and V27 values compared to LIN plans due to smaller PTV. LIN plans had better CI(27) and CI(54) values. Advantages of LIN treatment were no neccessity for fiducial marker use, which may cause pneumothorax, and significantly shorter beam-on treatment times. Both CK and LIN methods are suitable for lung SBRT.     

乳腺癌保留乳房手术后的放射治疗技术

放射治疗是早期乳腺癌保乳治疗的一个不可缺少的部分。荟萃分析显示：保乳术后放射治疗可以降低同侧乳腺肿瘤的复发率和患者的癌症病死率,放射治疗和未放射治疗患者的5年同侧乳腺局部复发率分别为79／6和26％,15年乳腺癌病死率分别为30．5％和35．9％。目前早期乳腺癌保乳术后放射治疗主要包括全乳房照射50．0Gy（每次2．0Gy）,然后瘤床补量照射10．O～16．0Gy。     

Adjuvant radiotherapy for breast cancer as a risk factor for the development of lung cancer

Women diagnosed with primary breast or lung cancer and recorded between 1972 and 1989 in our tumor registry were identified. Of 4,123 lung cancer patients and 3,537 breast cancer patients, 42 patients with both diagnoses were identified. The two malignancies were diagnosed simultaneously in five patients, lung cancer was diagnosed first in six patients and breast cancer was diagnosed first in 31 (p<0.001). Nineteen of those 31 patients received adjuvant radiotherapy for breast cancer and developed lung cancer a median of 17 years later. Of the 19 irradiated patients who subsequently developed lung cancer, 15 did so in the ipsilateral lung and only four had lung cancer contralateral to the previously irradiated site (p<0.001). Adjuvant radiotherapy for breast cancer as delivered decades ago may be an etiologic factor for lung cancer.     

A treatment planning study using non-coplanar static fields and coplanar arcs for whole breast radiotherapy of patients with concave geometry

PurposeA treatment planning study was performed to evaluate the performance of new radiotherapy techniques based on non-coplanar multiple fields or on dynamic conformal arcs for early stage breast treatments.Methods and materialsCT datasets of 7 different patients that were deemed unsuitable for tangential beam treatment due to a large volume of lung in the treatment fields were used as input for the study. Standard tangential field plans and inversely modulated IMRT plans were used as benchmark to evaluate performances of conformal plans with 3 non-coplanar fields (3F-NC), with 2 short dynamic conformal arcs (2-Arc) or hybrid plans with one static conformal field and one dynamic conformal arc (P-Arc). All plans were designed to achieve the higher target coverage and minimum ipsilateral lung involvement depending on the planning technique with a key objective to avoid involvement of the contralateral breast. The following planning objectives were selected. For PTV: D_1% (maximum significant dose) lower than 110% and D_99% (minimum significant dose) higher than 90%. For the ipsilateral lung a mean dose lower than 15 Gy and/or a volume receiving more than 20 Gy lower than 22%. For contralateral breast, all techniques but IMRT were set to have no beam impinging this organ at risk, while for IMRT plans were further designed to keep the mean dose lower than 5 Gy and to minimise the volume receiving a dose higher than 70% of the prescribed dose.ResultsP-Arc resulted to be on average a better technique, as it provides a PTV dose distribution highly conformal (Conformity index 1.45), homogeneous (D_5% − D_95% = 15.6%), with adequate coverage (V_90% = 96.4%) and a limited involvement of the ipsilateral lung (MLD ∼ 9 Gy, V_5Gy ∼ 36%, NTCP < 2%) when compared to four other treatment techniques. 3F-NC presented similar but slightly worse performances on target: Conformity index 1.57, D_5% − D_95% = 18.1%, V_90% = 95.7%). 3F-NC on ipsilateral lung resulted as the P-Arc. The tangential approach, the 2-Arc or the IMRT techniques, resulted to be inferior to the previous in either conformality (tangentials), ipsilateral lung sparing (tangentials, 2-Arc and IMRT) and in contralateral or healthy tissue involvement (IMRT).ConclusionFor early stage breast cancer when high sparing of lung tissues is required and no involvement of contralateral breast is allowed, the P-Arc or the 3F-NC techniques might be recommended in terms of dosimetric expectations.     

Feasibility of non-coplanar tomotherapy for lung cancer stereotactic body radiation therapy

To quantify the dosimetric gains from non-coplanar helical tomotherapy (HT) arcs for stereotactic body radiation therapy (SBRT) of lung cancer, we created oblique helical arcs by rotating patient's CT images. Ten, 20 and 30 degrees of yaws were introduced in the treatment planning for a patient with a hypothetical lung tumor at the upper, middle and lower portion of the right lung, and the upper and middle left lung. The planning target volume (PTV) was 43 cm(3). 60 Gy was prescribed to the PTV. Dose to organs at risk (OARs), which included the lungs, heart, spinal cord and chest wall, was optimized using a 2.5 cm jaw, 0.287 pitch and modulation factor of 2.5. Composite plans were generated by dose summation of the resultant plans. These plans were evaluated for its conformity index (R(x)) and percentile volume of lung receiving radiation dose of x Gy (V(x)). Conformity index was defined by the ratio of x percent isodose volume and PTV. The results show that combination of non-coplanar arcs reduced R(50) by 4.5%, R(20) by 26% and R(10) by 30% on average. Non-coplanar arcs did not affect V(20) but reduced V(10) and V(5) by 10% and 24% respectively. Composite of the non-coplanar arcs also reduced maximum dose to the spinal cord by 20-39%. Volume of chest wall receiving higher than 30 Gy was reduced by 48% on average. Heart dose reduction was dependent on the location of the PTV and the choice of non-coplanar orientations. Therefore we conclude that non-coplanar HT arcs significantly improve critical organ sparing in lung SBRT without changing the PTV dose coverage.     

Irradiation of bilateral orbital lymphoma: a non-coplanar technique with case reports

Bilateral synchronous involvement of the orbits by lymphoma is an uncommon event. Therefore, the irradiation techniques for this disease are not well refined. Depending on the technique used, one has to decide between underdosing the anterior segment of the orbit and the frequently involved lacrimal glands or to tolerate shield related in homogeneities in the range of 40 to 50% as well as higher doses to the midline structures, e.g. the optic chiasma. To avoid the above shortcomings we developed a technique by which half the prescribed dose is delivered by pairs of beams angulated in the transverse plane and the other half by pairs of beams angulated in the sagittal plane. Film dosimetry in a phantom confirms that the entire orbit, including its anterior portion, is well covered, the lens is protected, and the dose to the mid-sagittal structures is not increased. The dose inhomogeneity is in the range of 20% which represents a substantial improvement over alternative methods. Two irradiated patients with bilateral orbital lymphoma are presented with local control and no ophthalmic or other side effects as of last follow-up.     

左侧乳腺癌保乳术后放疗采用深吸气屏气技术肺部剂量Meta分析

目的:通过Meta分析探究左侧乳腺癌保乳术后放疗使用深吸气屏气技术对左肺剂量的影响。方法:2020年11月01日前检索PubMed、EMBASE、Web of Science寻找符合纳入标准的期刊文章,评价指标为左肺V20及左肺Dmean,通过Stata 12.0对提取的研究数据行Meta分析。结果:纳入20篇文献,共663例患者,异质性分析结果I2 检验(I-squared=69.5%)及Q检验(P=0.000)提示纳入20项研究间异质性较大。亚组分析结果:40例及以上组I2检验（I-squared=0%）及Q检验(P=0.909)提示各研究间无异质性;40例以下组I2检验（I-squared=76.8%）及Q检验(P=0.000) 提示异质性显著,说明异质性来源可能为样本量过小。最终对40例及以上组7项研究进行效应量合并,左肺V20在DIBH与自由呼吸（FB）两组间差异具有统计学意义［SMD=-0.28,95%CI（-0.41,-0.15）,Z=4.16,P=0.000］;左肺Dmean在DIBH与FB两组间差异具有统计学意义［SMD=-0.20,95%CI（-0.33,-0.07）,Z=2.96,P=0.003］。Egger回归检验结果提示本研究不存在明显的发表偏倚V20（P=0.971>0.05）及Dmean（P=0.666>0.05）。结论:左侧乳腺癌保乳术后放疗使用DIBH技术可以降低肺部照射剂量,从而减少放射性肺炎的发生概率,具有一定的临床价值。