Radiation therapy for intrahepatic malignancies

Historically, radiation was not used in the management of hepatocellular carcinoma and liver metastasis because of the low tolerance of the liver to radiation. More recently, improvements in radiation delivery using advanced techniques, such as 3D conformal radiation therapy, intensity-modulated radiation therapy, image-guided radiation therapy, stereotactic body radiation therapy, proton-beam therapy and internal radiation therapy, have enabled partial and selective irradiation of the liver with promising response rates and toxicity profiles. This review will discuss the different techniques of radiation that can now be used to treat intrahepatic malignancies and the important clinical studies in the medical literature.     

Apport de la radiothérapie guidée par l’image et repositionnement du patient dans le cancer anorectal

Intensity-modulated radiation therapy is recommended in anal squamous cell carcinoma treatment and is increasingly used in rectal cancer. It adapts the dose to target volumes, with a high doses gradient. Intensity-modulated radiation therapy allows to reduce toxicity to critical normal structures and to consider dose-escalation studies or systemic treatment intensification. Image-guided radiation therapy is a warrant of quality for intensity-modulated radiation therapy, especially for successful delivery of the dose as planned. There is no recommended international or national anorectal cancer image-guided radiation therapy protocol currently available. Dose-escalation trials or expert opinions about intensity-modulated/image-guided radiation therapy good practice guidelines recommend daily volumetric imaging throughout the treatment or during the five first fractions and weekly thereafter as a minimum. Image-guided radiation therapy allows to reduce margins related to patient setup errors. Internal margin, related to the internal organ motion, needs to be adapted according to short- or long-course radiotherapy, gender, rectal location; it can be higher than current recommended planning target volume margins, particularly in the upper and anterior part of mesorectum, which has the most significant movement. Image-guided radiation therapy based on volumetric imaging allows to take target volume shrinkage into account and to develop adaptive strategies, in particular for mesorectum shrinkage during rectal cancer treatment. Lastly, the emergence of new image-guided radiation therapy technologies including MRI (which plays a major role in pelvic tumours assessment and diagnosis) opens up interesting perspectives for adaptive radiotherapy, taking into account both organs’ movements and tumour shrinkage.     

Magnetic resonance‐guided radiation therapy: A review

Magnetic resonance‐guided radiation therapy (MRgRT) is a promising approach to improving clinical outcomes for patients treated with radiation therapy. The roles of image guidance, adaptive planning and magnetic resonance imaging in radiation therapy have been increasing over the last two decades. Technical advances have led to the feasible combination of magnetic resonance imaging and radiation therapy technologies, leading to improved soft‐tissue visualisation, assessment of inter‐ and intrafraction motion, motion management, online adaptive radiation therapy and the incorporation of functional information into treatment. MRgRT can potentially transform radiation oncology by improving tumour control and quality of life after radiation therapy and increasing convenience of treatment by shortening treatment courses for patients. Multiple groups have developed clinical implementations of MRgRT predominantly in the abdomen and pelvis, with patients having been treated since 2014. While studies of MRgRT have primarily been dosimetric so far, an increasing number of trials are underway examining the potential clinical benefits of MRgRT, with coordinated efforts to rigorously evaluate the benefits of the promising technology. This review discusses the current implementations, studies, potential benefits and challenges of MRgRT.     

光学表面成像(OSI)在放疗中的应用与展望

IGRT是目前放射肿瘤学领域最先进的技术。但是,目前最常用的图像引导技术如CBCT、EPID等由于额外辐射、影像质量差、不能实时监控等缺点而受到限制。OSI无额外辐射且能实时监测,经过大量研究评估和验证,其在引导摆位、实时监测放疗分次间和分次内运动、减少CBCT扫描频次以及呼吸门控等方面表现出巨大优势。本文就该类新技术及其在放疗中的应用作一综述和展望。     

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.     

三维超声图像引导系统质控评价体系建立

目的 分析三维超声IGRT系统(3DUS-IGRT)日常工作的稳定性和精确度,为软组织肿瘤放疗的临床运用提供依据。方法 用专用校准模体对3DUS-IGRT系统进行连续 1年的校准与质控,探索超声引导设备日常质控的方法并监测其稳定性和精度。结果 模体位置误差在3DUS-IGRT系统的模拟定位工作站(Sim工作站)与图像引导工作站(Guide工作站)均≤1 mm。结论 三维超声IGRT系统在整套严格且正确的校准与质控支持下性能稳定,能为软组织肿瘤精确放疗提供新的影像引导方法。     

Evaluation of image-guided helical tomotherapy for the retreatment of spinal metastasis

INTRODUCTION: Patients with vertebral metastasis that receive radiation therapy are typically treated to the spinal cord tolerance dose. As such, it is difficult to successfully deliver a second course of radiation therapy for patients with overlapping treatment volumes. In this study, an image-guided helical tomotherapy system was evaluated for the retreatment of previously irradiated vertebral metastasis. METHODS AND MATERIALS: Helical tomotherapy dose gradients and maximum cord doses were measured in a cylindrical phantom for geometric test cases with separations between the planning target volume (PTV) and the spinal cord organ at risk (OAR) of 2 mm, 4 mm, 6 mm, 8 mm, and 10 mm. Megavoltage computed tomography (CT) images were examined for their ability to localize spinal anatomy for positioning purposes by repeat imaging of the cervical spine in an anthropomorphic phantom. In addition to the phantom studies, 8 patients with cord compressions that had received previous radiation therapy were retreated to a mean dose of 28 Gy using conventional fractionation. RESULTS AND DISCUSSION: Megavoltage CT images were capable of positioning an anthropomorphic phantom to within +/-1.2 mm (2sigma) superior-inferiorly and within +/-0.6 mm (2sigma) anterior-posteriorly and laterally. Dose gradients of 10% per mm were measured in phantom while PTV uniformity indices of less than 11% were maintained. The calculated maximum cord dose was 25% of the prescribed dose for a 10-mm PTV-to-OAR separation and 71% of the prescribed dose for a PTV-to-OAR separation of 2 mm. Eight patients total have been treated without radiation-induced myelopathy or any other adverse effects from treatment. CONCLUSIONS: A technique has been evaluated for the retreatment of vertebral metastasis using image-guided helical tomotherapy. Phantom and patient studies indicated that a tomotherapy system is capable of delivering dose gradients of 10% per mm and positioning the patient within 1.2 mm without the use of special stereotactic immobilization.     

Emerging application of stereotactic body radiation therapy for gynecologic malignancies

Stereotactic body radiation therapy (SBRT) involves delivery of image-guided, ablative radiation doses to planning treatment volume(s) using sophisticated dosimetric planning and target localization. Early on, clinical investigators pursued SBRT for the treatment of early stage non-small-cell lung cancer, lung and liver oligometastases and spinal metastases. As a result of its clinical efficacy in these disease sites, SBRT has been explored in the management of persistent or recurrent gynecological cancers. This article will consider indications for SBRT application in gynecological cancer management, will reflect on outcomes from key SBRT clinical trials and will discuss new therapeutic roles of SBRT for gynecological cancers.     

High Dose Rate Brachytherapy for Inoperable Endometrial Cancer: a Case Series and Systematic Review of the Literature

Endometrial cancer is a common gynaecological cancer, is typically early stage and treated with surgery. For patients where surgery is difficult or dangerous, definitive radiation therapy is the next best option. This study included a single institution case series (step 1) and a systematic review of the literature (step 2). In step 1, all endometrial cancer cases that were treated with definitive image-guided brachytherapy at a single institution from 2008 to 2020 were retrospectively analysed. In step 2, a systematic review of Medline (PubMed) from 1975 to 2020 was carried out using the key words around endometrial cancer and brachytherapy, followed by a narrative synthesis. In total, in step 1, 31 cases were included in this study, stages I–IV, with 96.7% receiving external beam radiation. All patients received three fractions of 7.5 Gy or five fractions of 6 Gy high dose rate brachytherapy, with a median EQD2 of 75.55 (40–84.3). The 2-year Kaplan-Meier (KM) local control was 83.1% and the 2-year KM overall survival was 77.4%. There was no late toxicity ≥grade 3. In step 2, 19 articles were included in the final analysis, with between six and 280 patients. The local control ranged from 70 to 100%, with low toxicity. Definitive radiation therapy with image-guided brachytherapy seems to have good local control with low toxicity for patients who are poor surgical candidates.     

Combining a Customized Immobilization System with an Innovative Use of the ExacTrac System for Precise Volumetric Modulated Arc Therapy of Challenging Forearm Sarcomas

High-precision image-guided radiation therapy (RT) for tumors abutting the appendicular skeleton may mean technical difficulties and concerns among practitioners. This technical note addresses the specific challenge for normofractionated image-guided RT of a tumor target in a forearm through an unconventional use of a treatment verification system usually devoted to stereotactic RT.     

低分割三维适形调强放疗治疗局部进展期胰腺癌的临床观察

目的 探讨氟尿嘧啶（5-FU）联合低分割影像引导的三维适形调强放疗治疗局部进展期胰腺癌的疗效和毒副反应。方法 收集2011年6月至2014年12月间收治的37例经病理组织学证实的不可切除局部进展期胰腺癌,均采用CT引导下三维适形调强放疗技术,放疗采用大分割3.0～3.1 Gy／次,16次,DT 48～49.6 Gy;同步化疗方案：5-FU 350 mg／m2,每日1次,一周5次,与放疗同步进行。观察疗效和毒副反应,并随访生存。结果 所有患者均完成放疗。同步放化疗获CR 5例,PR 14例,SD 14例,PD 4例,有效率为51.4％（19/37）;临床受益反应有效者21例,临床受益率为56.8％（21/37）。同步放化疗期间发生3级以上骨髓抑制7例,严重胆道梗阻1例,胃十二指肠溃疡2例。37例患者1、2年无远处转移生存率分别为36.0％、4.8％;1、2年生存率分别为51.3％、11.6％。至随访截止日期,13例患者出现局部复发,26例患者出现远处转移。结论 氟尿嘧啶联合低分割影像引导的适形调强放疗治疗局部进展期胰腺癌疗效较好,毒副反应可耐受。     

A technique for adaptive image-guided helical tomotherapy for lung cancer

PURPOSE: The gross tumor volume (GTV) for many lung cancer patients can decrease during the course of radiation therapy. As the tumor reduces in size during treatment, the margin added around the GTV effectively becomes larger, which can result in the excessive irradiation of normal lung tissue. The specific goal of this study is to evaluate the feasibility of using image-guided adaptive radiation therapy to adjust the planning target volume weekly based on the previous week's CT image sets that were used for image-guided patient setup. METHODS AND MATERIALS: Megavoltage computed tomography (MVCT) images of the GTV were acquired daily on a helical tomotherapy system. These images were used to position the patient and to measure reduction in GTV volume. A planning study was conducted to determine the amount of lung-sparing that could have been achieved if adaptive therapy had been used. Treatment plans were created in which the target volumes were reduced after tumor reduction was measured. RESULTS: A total of 158 MVCT imaging sessions were performed on 7 lung patients. The GTV was reduced by 60-80% during the course of treatment. The tumor reduction in the first 60 days of treatment can be modeled using the second-order polynomial R = 0.0002t(2) - 0.0219t + 1.0, where R is the percent reduction in GTV, and t is the number of elapsed days. Based on these treatment planning studies, the absolute volume of ipsilateral lung receiving 20 Gy can be reduced between 17% and 23% (21% mean) by adapting the treatment delivery. The benefits of adaptive therapy are the greatest for tumor volumes > or =25 cm3 and are directly dependent on GTV reduction during treatment. CONCLUSIONS: Megavoltage CT-based image guidance can be used to position lung cancer patients daily. This has the potential to decrease margins associated with daily setup error. Furthermore, the adaptive therapy technique described in this article can decrease the volume of healthy lung tissue receiving above 20 Gy. However, further study is needed to determine whether adaptive therapy could result in the underdosing of microscopic extension.     

体表光学图像引导放疗质量控制指南

体表光学图像引导放疗系统（SGRT）是一套采用光学跟踪捕获患者的体表信息,记录和纠正患者分次间、分次内的摆位误差,以提高放疗精度的零辐射图像引导系统。为确保患者的治疗安全,必须对体表光学图像引导放疗系统采取必要的质量控制措施,因此,国家癌症中心/国家肿瘤质控中心组织专家制定了本指南。指南内容涉及：SGRT的定义和基本原理;SGRT的配准算法;SGRT的测量方法和类别;SGRT的质控要求;SGRT的放疗规范。     

体表光学图像引导放疗质量控制指南

体表光学图像引导放疗系统（SGRT）是一套采用光学跟踪捕获患者的体表信息,记录和纠正患者分次间、分次内的摆位误差,以提高放疗精度的零辐射图像引导系统。为确保患者的治疗安全,必须对体表光学图像引导放疗系统采取必要的质量控制措施,因此,国家癌症中心/国家肿瘤质控中心组织专家制定了本指南。指南内容涉及：SGRT的定义和基本原理;SGRT的配准算法;SGRT的测量方法和类别;SGRT的质控要求;SGRT的放疗规范。     

New devices in radiation oncology

The development of sophisticated conformal radiation techniques, such as intensity-modulated radiation therapy, image-guided radiation therapy, adaptative radiation therapy, and radiosurgery, implies precise and accurate targeting. To achieve this goal, a lot of new devices and techniques have been designed and are now available in radiation therapy departments : modern 3D-imaging systems, sophisticated treatment planning systems, breathing-adapted radiotherapy equipments (for gating and tracking techniques), in-room 3D-imaging systems, tomotherapy, etc. Purpose of this review is to briefly present the new equipments which are now used in radiation therapy departments in conformal therapy.     

Radiothérapie robotisée des cancers de prostate par CyberKnife™

After 3D conformal radiation therapy without and with modulated intensity, image-guided radiation therapy represents a new technological step. Should prostate cancer treatment using radiotherapy with the CyberKnife™ robotic system be considered as a new treatment and then investigated through classical clinical research procedure rather than a technical improvement of an already validated treatment? After a general presentation of the CyberKnife™, the authors focused on prostate cancer treatment assuming that, according to dosimetric and biological considerations, the treatment by robotic system appears comparable to high dose rate brachytherapy. For prostate cancer treatment are discussed: biological rational for hypofractionated treatment, high dose rate brachytherapy boost and interest of dose escalation. A comparison is presented between CyberKnife™ and other validated treatment for prostate cancer (radical prostatectomy, 3D conformal radiation therapy and low and high dose rate brachytherapy). In summary, CyberKnife™ treatment could be considered as a technical improvement of an already validated treatment in order to deliver a prostate boost after pelvic or peri-prostatic area irradiation. However, the clinical, biological and economical results must be precisely analyzed and could be assessed in the frame of a National Observatory based on shared therapeutic program.     

Review of image-guided radiation therapy

Image-guided radiation therapy represents a new paradigm in the field of high-precision radiation medicine. A synthesis of recent technological advances in medical imaging and conformal radiation therapy, image-guided radiation therapy represents a further expansion in the recent push for maximizing targeting capabilities with high-intensity radiation dose deposition limited to the true target structures, while minimizing radiation dose deposited in collateral normal tissues. By improving this targeting discrimination, the therapeutic ratio may be enhanced significantly. The principle behind image-guided radiation therapy relies heavily on the acquisition of serial image datasets using a variety of medical imaging platforms, including computed tomography, ultrasound and magnetic resonance imaging. These anatomic and volumetric image datasets are now being augmented through the addition of functional imaging. The current interest in positron-emitted tomography represents a good example of this sort of functional information now being correlated with anatomic localization. As the sophistication of imaging datasets grows, the precise 3D and 4D positions of the target and normal structures become of great relevance, leading to a recent exploration of real- or near-real-time positional replanning of the radiation treatment localization coordinates. This ‘adaptive’ radiotherapy explicitly recognizes that both tumors and normal tissues change position in time and space during a multiweek course of treatment, and even within a single treatment fraction. As targets and normal tissues change, the attenuation of radiation beams passing through these structures will also change, thus adding an additional level of imprecision in targeting unless these changes are taken into account. All in all, image-guided radiation therapy can be seen as further progress in the development of minimally invasive highly targeted cytotoxic therapies with the goal of substituting remote technologies for direct contact on the part of an operator or surgeon. Although data demonstrating clear-cut superiority of this new high-tech paradigm compared with more conventional radiation treatment approaches are scant, the emergence of preliminary data from several early studies shows that interest in this field is broad based and robust. As outcomes data accumulate, it is very likely that this field will continue to expand greatly. Although at present most of the work is being performed at major academic centers, the enthusiastic adoption of many of the devices and approaches being developed for this field suggest a rapid penetration into the community and the use of the technology by teams of specialists in the fields of radiation medicine, radiation physics and various branches of surgery. A recent survey of practitioners predicted very widespread adoption within the next 10 years.     

Review of image-guided radiation therapy

Image-guided radiation therapy represents a new paradigm in the field of high-precision radiation medicine. A synthesis of recent technological advances in medical imaging and conformal radiation therapy, image-guided radiation therapy represents a further expansion in the recent push for maximizing targeting capabilities with high-intensity radiation dose deposition limited to the true target structures, while minimizing radiation dose deposited in collateral normal tissues. By improving this targeting discrimination, the therapeutic ratio may be enhanced significantly. The principle behind image-guided radiation therapy relies heavily on the acquisition of serial image datasets using a variety of medical imaging platforms, including computed tomography, ultrasound and magnetic resonance imaging. These anatomic and volumetric image datasets are now being augmented through the addition of functional imaging. The current interest in positron-emitted tomography represents a good example of this sort of functional information now being correlated with anatomic localization. As the sophistication of imaging datasets grows, the precise 3D and 4D positions of the target and normal structures become of great relevance, leading to a recent exploration of real- or near-real-time positional replanning of the radiation treatment localization coordinates. This 'adaptive' radiotherapy explicitly recognizes that both tumors and normal tissues change position in time and space during a multiweek course of treatment, and even within a single treatment fraction. As targets and normal tissues change, the attenuation of radiation beams passing through these structures will also change, thus adding an additional level of imprecision in targeting unless these changes are taken into account. All in all, image-guided radiation therapy can be seen as further progress in the development of minimally invasive highly targeted cytotoxic therapies with the goal of substituting remote technologies for direct contact on the part of an operator or surgeon. Although data demonstrating clear-cut superiority of this new high-tech paradigm compared with more conventional radiation treatment approaches are scant, the emergence of preliminary data from several early studies shows that interest in this field is broad based and robust. As outcomes data accumulate, it is very likely that this field will continue to expand greatly. Although at present most of the work is being performed at major academic centers, the enthusiastic adoption of many of the devices and approaches being developed for this field suggest a rapid penetration into the community and the use of the technology by teams of specialists in the fields of radiation medicine, radiation physics and various branches of surgery. A recent survey of practitioners predicted very widespread adoption within the next 10 years.     

Functional imaging in treatment planning in radiation therapy: a review

The remarkable technical developments obtained in radiation oncology have resulted in an increasing use of image-based treatment planning in radiation therapy for three-dimensional and intensity modulated radiation therapy, stereotactic irradiation and image-guided brachytherapy. There has been increased use of computer-based record and verify systems as well as electronic portal imaging to enhance treatment delivery. From the data presented it is evident that PET scanning and other functional imaging techniques play a major role in the definition of tumor extent and staging of patients with cancer. The recent introduction of a combined CT and PET scanner will substantially simplify image acquisition and treatment planning.     

医学图像融合技术在肿瘤放射治疗中的应用

医学图像融合技术一个非常重要的应用领域就是肿瘤的放射治疗,特别是对于精确放射治疗。本文简介医学图像融合技术的分类及主要方法和实施步骤,并综述各种图像融合技术在不同肿瘤放疗中的应用,对其在生物适形放射治疗中的应用前景作一展望。