Determining DVH parameters for combined external beam and brachytherapy treatment: 3D biological dose adding for patients with cervical cancer

Purpose

To compare two methods of DVH parameter determination for combined external beam and brachytherapy treatment of cervical cancer.

Materials and methods

Clinical treatment plans from five patients were used in this study. We simulated two applications given with PDR (32 × 60 cGy per application, given hourly) or HDR (4 × 7 Gy in two applications; each application of two fractions of 7 Gy, given within 17 h) standard and optimised treatment plans, all combined with IMRT (25 × 1.8 Gy). Additionally, we simulated an external beam (EBRT) boost to pathological lymph nodes or the parametrium (7 × 2 Gy).We determined D90 of the high-risk CTV (HR-CTV) and D_2cc of bladder and rectum in EQD2 in two ways. (1) ‘Parameter adding’: assuming a uniform contribution of the EBRT dose distribution and adding the values of DVH parameters for the two brachytherapy insertions, and (2) ‘distributions adding’: summing 3D biological dose distributions of IMRT and brachytherapy plans and subsequently determining the values of the DVH parameters. We took α/β = 10 Gy for HR-CTV, α/β = 3 Gy otherwise and half-time of repair 1.5 h.

Results

Without EBRT boost, ‘parameter adding’ yielded a good approximation. With an EBRT boost to lymph nodes, the total D90 HR-CTV was underestimated by 2.6 (SD 1.3)% for PDR and 2.8 (SD 1.4)% for HDR. This was even worse with a parametrium boost: 9.1 (SD 6.2)% for PDR and 9.9 (SD 6.2)% for HDR.

Conclusion

Without an EBRT boost ‘parameter adding’, as proposed by the GEC-ESTRO, yielded accurate results for the values for DVH parameters. If an EBRT boost is given ‘distributions adding’ should be considered.     

Implementation of image-guided brachytherapy for cervix cancer in the UK: progress update

Aims

Image-guided brachytherapy (IGBT) is the new gold standard for cervix cancer brachytherapy. In 2009, the Royal College of Radiologists (RCR) published a guidance document to facilitate the implementation of IGBT for cervix cancer in the UK. This paper reports the progress since the publication of the RCR document.

Materials and methods

Questionnaires were sent to 45 UK centres known to offer brachytherapy for cervix cancer in 2011. Replies were received from 43 (96%) centres. Details collected included brachytherapy machine, imaging technique for brachytherapy planning, applicator design and total dose to point A from external beam radiotherapy and brachytherapy. The results were compared with the 2008 survey reported in the RCR document.

Results

The number of centres offering computed tomography (CT) or magnetic resonance imaging (MRI)-based IGBT for cervix cancer has increased to 32 (71%) in 2011 compared with 12 (26%) in 2008. Although the most common applicator design in 2011 remains the tandem-ovoid applicator (71%), more respondents are using the tandem-ring applicator (29% versus 9% in 2008). Only seven (16%) centres are routinely prescribing <70 Gy₁₀ to point A in 2011 compared with10 (22%) in 2008.

Conclusion

Considerable progress with implementing IGBT for cervix cancer has been made in the UK since the publication of the RCR guidance document.     

影像引导宫颈癌三维腔内放疗的临床初步观察

背景与目的：放射治疗是宫颈癌的主要治疗方法。通过分析苏州大学附属第一医院放疗科收治的31例初治宫颈癌患者三维腔内放疗的剂量体积直方图(dose-volume histogram,DVH)剂量分布和临床结果,观察影像引导宫颈癌三维后装放疗患者的近期疗效及放射反应。方法：选取2013年5月—2014年12月在苏州大学附属第一医院放疗科行根治性放疗的31例初治宫颈癌患者,FIGO期为Ⅱa~Ⅳ期。每例患者接受4~6次CT引导下的三维后装放疗,单次高危临床靶区(high risk-clinical target volume,HR-CTV)给予400~600 cGy处方剂量,31例患者共计153次施源器置入,采用¹⁹²Ir高剂量率后装治疗机实施腔内放疗。分析内外照射的HRCTVD90、膀胱D2cc、乙状结肠D2cc、直肠D0.1cc和直肠D2cc,采用EQD2进行剂量计算。按照RTOG/EORTC放射反应评分标准和RECIST 1.1评价标准分析放射反应和近期疗效。结果：膀胱、直肠、乙状结肠均无3级及以上急性或慢性放射反应。2例患者发生后期直肠出血(2级),经止血和灌肠等对症处理后症状改善。放疗后1~3个月完全缓解率(complete remission,CR)为93.55%(29/31),1年局部控制率(local control rate,LCR)为93.55%(29/31),1年无进展生存率(progression-free survival,PFS)为90.32%(28/31)。结论：CT引导的三维腔内放疗联合外照射治疗局部晚期宫颈癌,定位精确,靶区剂量充足,危及器官的受照剂量可见、可控、可信,提高了患者的治疗耐受性,避免了重度放射反应的发生,大大提高了患者治疗后的生活质量,值得推广应用。     

宫颈癌图像引导三维近距离后装治疗中国专家共识

近年来宫颈癌三维近距离治疗(BT)技术在中国得到快速发展。与二维技术相比,宫颈癌图像引导的三维BT技术可以提高局控率、生存率。三维BT要求用体积剂量参数评价治疗靶区及危及器官受量,探索体积剂量参数与局控率、并发症发生率之间关系。BT开始时肿瘤残留体积及形状与局控率有明确相关性,应当结合MRI、超声、妇科检查结果,综合判断残留肿瘤体积。腔内联合组织间插植技术可以改善靶区剂量分布。严格遵守靶区勾画、体积剂量原则以及质控要求。为规范其应用,中华医学会放射治疗学分会近距离治疗学组、中国医师协会放射肿瘤分会妇科肿瘤学组、中国抗癌协会近距离治疗专委会结合中国国情联合制定此专家共识。     

Chinese expert consensus on three-dimensional image guided brachytherapy for cervical cancer

In recent years, image-guided brachytherapy (IGBT) for cervical cancer has been rapidly developed in China. IGBT can improve local control and survival rates in patients with locally advanced cervical cancer compared with the two-dimensional technology. Dose volume histogram parameters for the high risk clinical target volume (HR-CTV), intermediate risk clinical target volume (IR-CTV) and organs at risk should be calculated, reported, and adopted to explore the relationship with local control rate and incidence of complications. The volume and topography of residual tumor at the initiation of IGBT is significantly correlated with local control rate. The residual tumor should be assessed by the combination of MRI, ultrasound images and gynecological examinations. The appropriate implant with intracavitary applicator supplemented with interstitial needles can improve the dose distribution in the target area. Target delineation, dose assessment and quality control should be conducted strictly according to the principles and consensus. To standardize its application, the Chinese expert consensus was jointly formulated by Brachytherapy Group of China Society for Radiation Oncology, the Gynecological Oncology Group of Chinese Association for Therapeutic Radiation Oncologists, and the Brachytherapy Special Committee of Chinese Anti-Cancer Association in light of the national conditions in China.     

超声图像引导宫颈癌近距离治疗的研究进展

近距离治疗是宫颈癌根治性放疗不可或缺的治疗方法。随着影像技术的快速发展,三维图像引导已应用到宫颈癌近距离治疗中。三维超声凭借其优越的软组织成像特点,兼具经济、高效、便捷等优势,继CT和MRI后逐渐应用于引导宫颈癌近距离治疗。本综述通过查阅大量相关文献,总结了超声图像引导宫颈癌近距离治疗的研究进展,以供研究参考。     

超声图像引导宫颈癌近距离治疗的研究进展

近距离治疗是宫颈癌根治性放疗不可或缺的治疗方法。随着影像技术的快速发展,三维图像引导已应用到宫颈癌近距离治疗中。三维超声凭借其优越的软组织成像特点,兼具经济、高效、便捷等优势,继CT和MRI后逐渐应用于引导宫颈癌近距离治疗。本综述通过查阅大量相关文献,总结了超声图像引导宫颈癌近距离治疗的研究进展,以供研究参考。     

3D CT-based high-dose-rate brachytherapy for cervical cancer: Clinical impact on late rectal bleeding and local control

Background and purpose

To identify the impact of 3D CT-based high-dose-rate intracavitary radiotherapy (ICR) on late rectal bleeding (LRB) and local control (LC) in patients with cervical cancer.

Material and methods

The outcomes of 97 consecutive patients treated with 3D CT-based ICR (3D-ICR) were compared with those of 133 consecutive historical patients with conventional 2D brachytherapy planning (2D-ICR). The median follow-up periods were 41 and 56 months for the 3D and 2D groups, respectively.

Results

The overall rectal bleeding rate was similar between the groups (42% for 3D-ICR vs. 44% for 2D-ICR); however, the incidence of severe LRB was higher in the 2D-ICR group than in the 3D-ICR group (13% vs. 2%, respectively; p = 0.02). In multivariate analysis, the factors associated with severe LRB were tumor >4 cm (12% vs. 3%) and 2D-ICR (10% vs. 2%). The LC rates were 97% and 91% for 3D-ICR and 2D-ICR, respectively (p = 0.14); the progression-free survival rate was 80% for both groups. A significant difference in the LC rates between the two groups was observed in patients with larger tumor sizes with the tumor diameter of over 4 cm (98% vs. 81% by 3D-ICR vs. 2D-ICR, respectively; p = 0.02).

Conclusions

The implementation of 3D-ICR in radiotherapy for cervical cancer can reduce the incidence of severe LRB and may improve the LC rate.     

The use of magnetic resonance imaging for image-guided brachytherapy

Progress has been made in the delivery of brachytherapy, from low-dose rate (LDR) to high-dose rate (HDR) treatments, allowing for dose optimisation, conformal treatments, improved radiation protection, and improved accuracy and efficiency. Image-guided brachytherapy, incorporating spatial and temporal changes, is now possible with advanced imaging and treatment technology. This report reviews the evidence for the benefits of image-guided brachytherapy using magnetic resonance imaging (MRI), mainly for cervix and prostate cancer, but also possibilities for other tumour sites. It also emphasises the need for a dedicated MRI unit for brachytherapy.     

Image-based brachytherapy for cervical cancer

Cervical cancer is the third most common cancer in women worldwide; definitive radiation therapy and concurrent chemotherapy is the accepted standard of care for patients with node positive or locally advanced tumors > 4 cm. Brachytherapy is an important part of definitive radiotherapy shown to improve overall survival. While results for two-dimensional X-ray based brachytherapy have been good in terms of local control especially for early stage disease, unexplained toxicities and treatment failures remain. Improvements in brachytherapy planning have more recently paved the way for three-dimensional image-based brachytherapy with volumetric optimization which increases tumor control, reduces toxicity, and helps predict outcomes. Advantages of image-based brachytherapy include: improved tumor coverage (especially for large volume disease), decreased dose to critical organs (especially for small cervix), confirmation of applicator placement, and accounting for sigmoid colon dose. A number of modalities for image-based brachytherapy have emerged including: magnetic resonance imaging (MRI), computed tomography (CT), CT-MRI hybrid, and ultrasound with respective benefits and outcomes data. For practical application of image-based brachytherapy the Groupe Europeen de Curietherapie-European Society for Therapeutic Radiology and Oncology Working Group and American Brachytherapy Society working group guideline serve as invaluable tools, additionally here-in we outline our institutional clinical integration of these guidelines. While the body of literature supporting image-based brachytherapy continues to evolve a number of uncertainties and challenges remain including: applicator reconstruction, increasing resource/cost demands, mobile four-dimensional targets and organs-at-risk, and accurate contouring of “grey zones” to avoid marginal miss. Ongoing studies, including the prospective EMBRACE (an international study of MRI-guided brachytherapy in locally advanced cervical cancer) trial, along with continued improvements in imaging, contouring, quality assurance, physics, and brachytherapy delivery promise to perpetuate the advancement of image-based brachytherapy to optimize outcomes for cervical cancer patients.     

Dose volume parameter D2cc does not correlate with vaginal side effects in individual patients with cervical cancer treated within a defined treatment protocol with very high brachytherapy doses

The study aimed to determine whether post-radiation vaginal side effects in cervical cancer patients can be correlated with DVH parameter D_2cc. The result was negative in that no correlation could be demonstrated between D_2cc and the presence and grade of side effects in this patients’ subset treated with high brachytherapy doses.     

宫颈癌术后近距离治疗的研究进展

放疗为宫颈癌术后辅助治疗的重要组成部分,随着放疗技术的发展,近距离治疗越来越多的应用于宫颈癌术后患者,多用作外照射的后期加量。本文将对宫颈癌术后放疗指征及近距离治疗应用情况予以阐述。     

局部晚期宫颈癌三维适形近距离放疗CT与MRI定位的对比研究

目的 比较CT与MRI图像引导的局部晚期宫颈癌三维适形近距离放疗靶区及剂量学的差异,为优化影像引导方式及改进治疗方案提供依据。方法 2014年本院行宫颈癌根治性放疗的局部晚期患者 13例,均行外照射+MRI引导三维适形腔内+插植近距离治疗。每次后装均实施MRI和CT扫描,并分别进行靶区勾画、腔内+插植和模拟去除插植针单纯腔内治疗计划设计。对两组扫描数据进行配对t检验。结果 MRI比CT的高危CTV的宽度、体积小[(38.0±9.4) mm∶(45.1±8.7) mm (P=0.000)、(34.2±15.3) cm³∶42.9±20.4 cm³(P=0.002)],中危CTV的宽度、厚度、体积也小[(58.8±9.4) mm∶(65.4±10.3) mm (P=0.000)、(34.8±6.3) mm∶(37.5±6.3) mm (P=0.001)、(90.9±28.5) cm³∶(109.0±36.4) cm³(P=0.000)]。MRI较CT的高危、中危CTV的 D_90%均增高[87.6 Gy∶85.8 Gy (P=0.013)、67.7 Gy∶66.3 Gy (P=0.005)],而膀胱、直肠 D_{2 cm³}均降低[73.1 Gy∶75.5 Gy (P=0.011)、61.0 Gy∶65.7 Gy (P=0.000)]。结论 CT比MRI定位过度评估靶区宽度;应用MRI定位靶区和正常组织剂量有明显优势;腔内+插植可弥补CT引导造成的靶区剂量下降。     

MRI引导下的宫颈癌三维后装治疗进展

宫颈癌是造成全球女性肿瘤患者死亡的主要原因之一,放疗是宫颈癌的主要治疗手段,而后装治疗是宫颈癌放疗不可缺少的组成部分,外照射联合后装治疗适用于无远处转移的各期初治或复发宫颈癌患者。MRI具有良好的软组织分辨率,在精确靶区范围、保护OAR以及改善患者临床结局等方面有着独特优势;近来许多研究证实了MRI引导下的宫颈癌三维后装的可行性及优越性。本文主要从相关MR成像技术、施源器选择、靶区勾画与评估以及MRI引导下的三维后装治疗所带来的临床效应等方面进行阐述。     

宫颈癌近距离放疗应用进展

近距离治疗是宫颈癌放射治疗环节中的重要组成部分.近距离放疗技术发展迅速,治疗方式多样化,近距离放疗方式包括:腔内近距离放疗、插植近距离放疗及放射性粒子植入等.本文旨在介绍腔内、插植以及放射性粒子植入的应用进展,主要回顾腔内结合插植近距离放疗的应用情况.