Stereotactic Radiosurgery and Stereotactic Body Radiation Therapy A Comprehensive Guide: A Comprehensive Guide
Abstract
This book is a comprehensive review of stereotactic radiosurgery (SRS) and stereotactic body radiation therapy (SBRT): its physics, clinical evidence, indications, and future directions. The utilization of stereotactic radiosurgery (SRS) and stereotactic body radiation therapy (SBRT) is increasing internationally because of several factors. First, it offers patients a local treatment option that has demonstrated effectiveness similar to traditional surgery without the morbidity of general anesthesia and open surgical resection. Second, recent advancements in the quality of scientific evidence supporting a SRS or SBRT-containing approach in patients continues to evolve and demonstrate favorable disease-specific outcomes with little, if any, toxicity in various anatomic disease sites and for various conditions including cancer, benign tumors, and other psychiatric and neurologic conditions. Third, and most provocatively, is the notion that definitive local therapy (i.e. SRS or SBRT) in patients with cancer can boost the immune system to fight cancer in other sites throughout the body. While traditional medical knowledge would suggest that all patients with metastatic cancer are incurable, there is a mounting body of evidence that there is a subset of these patients that can be cured with definitive SRS or SBRT. This volume thus delves into each of these benefits and aspects of treatment, guiding physicians to the best treatment plan for their patients.
Expert, international authors provide guidelines for SRS and SBRT use by clinicians. Chapters are divided into six main sections: Radiobiology of Radiosurgery and Stereotactic Body Radiation Therapy, Intracranial Radiosurgery Technique, Intracranial Radiosurgery by Indication, Stereotactic Body Radiation Therapy Technique, Stereotactic Body Radiation Therapy by Indication, The Future of Radiosurgery and SBRT. Overall physics are explained, as well as specific considerations for particular surgical tools (including the Leksell Gamma Knife and Accuray CyberKnife), techniques (including fractionated and charged particle radiosurgery), and anatomic sites (including brain metastases, pituitary tumors, and the prostate). Detailed images and charts enhance the chapters. This book provides physicians with a single, practical resource incorporating both of these broad categories of treatment, SRS and SBRT, and better defines the current role and the direction of radiosurgery.
... После проведения РХ/СТЛТ, в отличие от стандартных режимов облучения, клетки погибают чаще не по пути апоптоза, а некроптоза, который сопровождается сильным иммунным ответом. При высокодозной ЛТ (более 10 Гр за фракцию) биологические эффекты не согласуются ни с классической линейно-квадратичной моделью, ни с одной из множества предложенных модификаций, что смещает радиобиологическую парадигму в сторону определяющей роли сосудистых и иммунных механизмов [1,3,5,6,7]. При возникновении сомнений, связанных с токсичностью нормальных тканей при СРХ/СТЛТ, следует соблюдать эмпирически установленные ограничения доз и допуски из литературы [8,9]. ...
... Сосудистые эффекты РХ/СТЛТ выглядят иначе -преобладает непрямая гибель опухолевых клеток, возникающая главным образом в результате ишемии после летального повреждения эндотелиальных клеток и разрушения микрососудов, что обеспечивают немедленную тяжелую сосудистую реакцию. К механизмам непрямой гибели относятся: 1) прямое повреждение эндотелиальных клеток микрососудов; 2) взаимодействие между радиорезистентными опухолевыми стволовыми клетками и микрососудистыми эндотелиальными клетками и 3) радиоиндуцированный абскопальный немишенный «эффект свидетеля», заключающийся в передаче радиациоиндуцированных сигналов, прежде всего сигналов апоптоза, от облученных клеток необлученным при активном участии иммунных механизмов [5,7,11,12,14,15]. ...
... Известно, что уровень оксигенации -одно из определяющих условий радиочувствительности, а реакция гипоксических тканей на лучевую терапию слабая. Наличие молекулярного кислорода (O 2 ) необходимо для реализации цитотоксических эффектов излучения, опосредованных образованием активных форм кислорода (reactive oxygen species -ROS) [5,14,16,18]. ...
Литературный обзор описывает значение сосудистых механизмов в реализации радиобиологических эффектов высокодозной лучевой терапии. Основные понятия радиобиологии можно свести к нескольким тесно взаимосвязанным моделям: линейно-квадратичной, сосудистой, иммунной и немишенной. Каждая из них описывает свое звено совокупного ответа на проводимое облучение, а их роль и вклад меняются в зависимости, прежде всего от разовых доз, а затем от режимов фракционирования и общих доз. Накопленные данные свидетельствуют о целесообразности формирования единой обобщающей модели. Сосудистая сеть имеет важное значение в пролиферации и выживании опухолевых клеток, во многом определяя условия микросреды и общий ответ на лучевую терапию. Высокие дозы облучения за фракцию (более 10Гр) приводят к сосудисто-эндотелиальному апоптозу, немедленной тяжелой сосудистой реакции и глубокой ишемии опухоли. Этот феномен связан с активацией кислой сфингомиелиназы, последующим гидролизом сфингомиелина, генерирующего церамид, индуцирующий трансмембранный сигнал апоптоза.
... The brain, however, is a critical organ and does not easily tolerate the high BED needed to kill melanoma brain metastases [2]. Stereotactic radiosurgery is a treatment technique that provides high-dose radiation within the metastasis, but, at the outside edge of the tumor, provides a very steep reduction of radiation dose to the surrounding brain tissue [19][20][21]. This is achieved by using multiple beams of radiation from many different angles, with each beam conforming to the shape that the tumor presents from each angle, with each beam passing through the center of the tumor. ...
... It may also be referred to as stereotactic ablative body radiotherapy (SABR) [31]. When the entire course of treatment is given in a single fraction, it is referred to as stereotactic radiosurgery (SRS) [21]. Because SBRT if given with very large doses of radiation delivered per fraction, the BED of SBRT is quite high [32]. ...
... SBRT is also frequently used when there is a need to reirradiate a previously treated tumor [44][45][46]. High BED treatment is often necessary to defeat tumors that have proven resistant to a prior course of radiation, and SBRT can limit the amount of dose delivered to normal tissues that may have been previously radiated and are resultantly less tolerant to radiation [21]. This is true especially in the setting of reirradiation of spinal metastases, where critical organs such as the spinal cord are only a few millimeters away [44]. ...
Purpose of Review
Radiation therapy is a treatment modality used in the management of patients with cancer that utilizes ionizing radiation to kill cells. Herein, we provide a brief review of basic radiobiology principles to describe the mechanisms of radiation effects and injuries.
Recent Findings
With technologic advances, radiation therapy has evolved significantly over the past several decades. Such advances have changed the way in which radiation reaches target tissue while sparing normal tissue, and subsequently the doses of radiation that can be administered.
Summary
From a rehabilitation standpoint, it is critical to understand the type of radiation therapy used, the dose prescribed, and the volume to which the radiation therapy was administered when treating a patient with a radiation-related injury. We describe the fundamentals of radiation therapy planning and administration as well as commonly utilized modern radiation therapy techniques.
... постигане на "хирургичен" резултат (от където произлиза и името на метода) без директен достъп, без анестезия, разрези и шевове, без болка, каквито имаме при хирургичните методи (Petrov, R. Lazarov, D. Ganchev, N. Bildirev, I. Stanimirov, M. Mihaylova. 2021), (Trifiletti D, Chao S, Sahgal A, Sheehan J eds., 2019). Методът блокира патологични процеси и води до загиване на злокачествени клетки. ...
... радиохирургията първоначално е била само краниална, но с напредването на лъчелечението и появата на други платформи за радиохирургия е започнато прилагане и в други части на тялото (Petrov, R. Lazarov, D. Ganchev, N. Bildirev, I. Stanimirov, M. Mihaylova. 2021), (Trifiletti D, Chao S, Sahgal A, Sheehan J eds., 2019). В англоезичната литература са наложени термините Stereotactic Radiosurgery (SRS) когато се има предвид краниално приложение и SBRT (Stereotactic Body Radiotherapy) и SABR (Stereotactic Ablative Body Radiotherapy) -когато се говори за други локализации в тялото. ...
Stereotactic radiosurgery is a non-invasive medical procedure, a form of radiotherapy, in which high doses of ionizing radiation, precisely guided with stereotactic method, are applied in small target volumes within the body, aiming surgery-like effect. Primary malignant tumors, metastases, as well as for some non-oncological diseases are successfully treated with radiosurgery. It is performed on contemporary linear accelerators with radiosurgery capabilities, as well as on specialized treatment units such as the Gamma Knife. We present the specificities of Gamma Knife radiosurgery and the new treatment possibilities available and reimbursed for the Bulgarian patients, with the introduction in clinical operation of the latest generation Gamma Knife Icon of the this "gold standard" in cranial radiosurgery at the Heart and Brain Center of Clinical Excellence in Pleven. Presented are the challenging completely new for the Bulgarian practice technological features and workflow aspects with focus on the specific and important role and responsibilities of the radiotherapy technicians in the whole process.
... Recently, the debate about dose hypofractionation has been relaunched with the advent of stereotactic technologies that permit targeting the tumor with great precision, limiting therefore the exposure of healthy tissues surrounding the tumor. Particularly, anticancer treatments with stereotactic radiosurgery (SRS) and stereotactic body radiation therapy (SBRT) are based on the combination of a high-precision tumor targeting with hypofractionation [89]. Cyberknife (Accuray Incorporated, Sunnyvale, CA, USA) is one of the most recent and innovative techniques developed for the SBRT. ...
... Studies have shown the efficiency and safety of the SRS and SBRT techniques in many instances, including some involving the Cyberknife. Still, however, owing to the lack of a clear radiobiological mechanistic model that will define objective criteria, no consensus about the total dose, dose per fraction, and treatment duration has been achieved [89]. ...
At the end of the nineteenth century, Wilhelm Conrad Roentgen discovered X-rays and Henri Becquerel discovered radioactivity. In the early years after that, there was a lot of misunderstanding regarding the effects of ionizing radiation and its practical applications. Medical employment of ionizing radiation began immediately after the discovery of X-rays. However, until World War Two, radioactive substances were widely used and misused. Until the early 1960s, ionizing radiation was commonly used for treatment of various diseases. Since then, however, radiation therapy has been confined nearly exclusively to cancer treatment. Two factors contributed to the phasing out of radiotherapy for non-oncological purposes: the growing awareness of radiation carcinogenesis and the development of efficient drugs (primarily, antibiotics).
Radio-induced cancers have been known for above a century. The linear no-threshold (LNT) risk model considers that cancer risk is proportional to radiation dose and no radiation exposure is safe. Although LNT has never been scientifically validated, it is used for the management of radiological protection. Progress in understanding the carcinogenesis associated with ionizing radiation has resulted from a better comprehension of the DNA damage repair and other defense mechanisms.
... Radiotherapy is a treatment possibility for patients suffering from cancer. It employs ionizing radiation and cutting-edge technology to target large and small cancer volumes with high spatial accuracy by means of stereotactic radiosurgery (SRS) and stereotactic body radiation therapy (SBRT) [1,2]. The most important aspect is increasing the dose of radiation directed to cancer cells while sparing healthy tissue. ...
This work describes the development of a reusable 2D detector based on radiochromic reaction for radiotherapy dosimetric measurements. It consists of a radiochromic gel dosimeter in a cuboidal plastic container, scanning with a flatbed scanner, and data processing using a dedicated software package. This tool is assessed using the example of the application of the coincidence test of radiation and mechanical isocenters for a medical accelerator. The following were examined: scanning repeatability and image homogeneity, the impact of image processing on data processing in coincidence tests, and irradiation conditions—monitor units per radiation beam and irradiation field are selected. Optimal conditions for carrying out the test are chosen: (i) the multi-leaf collimator gap should preferably be 5 mm for 2D star shot irradiation, (ii) it is recommended to apply ≥2500–≤5000 MU per beam to obtain a strong signal enabling easy data processing, (iii) Mean filter can be applied to the images to improve calculations. An approach to dosimeter reuse with the goal of reducing costs is presented; the number of reuses is related to the MUs per beam, which, in this study, is about 5–57 for 30,000–2500 MU per beam (four fields). The proposed reusable system was successfully applied to the coincidence tests, confirming its suitability as a new potential quality assurance tool in radiotherapy.
... Természetesen a betegszelekciónál figyelembe kell venni a prognózist, a beteg általános állapotát és az intrakraniális elváltozások méretét, kiterjedését, elhelyezkedését. Sztereotaxiás sugárkezelés elsősorban jó prognózisú, szoliter, illetve oligometasztatikus agyi áttétes betegeknél jön szóba, azonban nincs egy meghatározott felső korlát a kezelhető áttétek számát illetően (5). Ez országtól és centrumtól függően változik, valamint a primer daganat szövettana, a beteg általános állapota, az alapbetegség kiterjedése és a szisztémás kezelési lehetőségek is befolyásolják. ...
Stereotactic radiosurgery is today a well-established treatment modality for various intracranial pathologies. The principle of high dose focused intracranial radiation guided by stereotactic technique ("Gamma Knife") was introduced by the Swedish neurosurgeon Prof. Lars Leksell in 1968. After the advent of CT and later MR imaging, stereotactic radiosurgery evolved rapidly regarding indications, and new technical solutions made it possible for linear accelerator systems to perform radiosurgery. A huge number of patients are treated yearly worldwide with this technology. In this article we overview the major indications, advantages and possible complications of stereotactic radiosurgery.
... Radiation therapy is a technique that uses ionizing radiation in cancer treatment. Thanks to the development of computers and irradiation techniques, even small tumours can be eliminated with high precision using stereotactic body radiation therapy (SBRT) and stereotactic radiosurgery (SRS) [1,2]. Quality assurance (QA) testing is required to ensure treatment excellence [3,4]. ...
Dynamically evolving radiotherapy instruments require advancements in compatible 3D dosimetry systems. This paper reports on such tools for the coincidence test of the mechanical and radiation isocenter for a medical accelerator as part of the quality assurance in routine radiotherapy practice. Three-dimensional polymer gel dosimeters were used in combination with 3D reading by iterative cone beam computed tomography and 3D data processing using the polyGeVero-CT software package. Different polymer gel dosimeters were used with the following acronyms: VIP, PAGAT, MAGIC, and NIPAM. The same scheme was used for each dosimeter: (i) irradiation sensitivity test for the iterative cone beam computed tomography reading to determine the appropriate monitor unit for irradiation, and (ii) verification of the chosen irradiation conditions by a star-shot 2D irradiation of each 3D dosimeter in the direction of performing the test. This work concludes with the optimum monitor unit per beam for each selected 3D dosimeter, delivers schemes for quick and easy determination of the radiation isocenter and performing the coincidence test.
... an obliteration dose while minimizing the risk of toxicity to normal brain (NB), larger AVMs are treated either with hypofractionated stereotactic radiotherapy (SRT) in which the treatment is delivered in 2-5 fractions 6 or with volume-staged SRS (VS-SRS) in which the AVM is divided into separate stage volumes, and each stage volume is treated with a high dose delivered in a single fraction. 1,3,8 A time period between the stages is thought to allow for normal tissue repair so that each stage can be treated as a separate target, and higher doses that improve obliteration rate can be delivered. ...
Volume staging involves dividing the target volume into smaller parts and treating each part separately. In this study, the feasibility of volume‐staged stereotactic radiosurgery (VS‐SRS) on a linear accelerator using volumetric modulated arc therapy (VMAT) and a frameless patient positioning system is investigated. Ten patients, previously treated with hypofractionated stereotactic radiotherapy with arteriovenous malformation (AVM) sized from 1.6 to 4.0 cm in diameter, were selected. VS‐SRS plans were created with the VMAT technique on the Varian Eclipse treatment planning system (TPS) using the TrueBeam STx linear accelerator. For each patient, an AVM‐VMAT set was planned with the AVM as the target and a PTV‐VMAT set using the (PTV = AVM+1 mm) as the target. All targets were divided into two sub‐volumes. The TPS data from the AVM‐VMAT plans was compared to Gamma Knife (GK) VS‐SRS plan data available in the literature. The AVM‐VMAT and PTV‐VMAT plans were compared to investigate the effect of a 1 mm PTV margin on normal brain (NB) dose. End‐to‐end testing was performed using a GaFchromic EBT3 film and point‐dose measurements. Dosimetric effects of multiple setups were investigated through film‐to‐film comparisons. Median target dose coverage, NB V12Gy, and conformity index for the AVM‐VMAT plans were 97.5%, 17 cm3, and 0.8, respectively. PTV‐VMAT plans attained comparable target dose coverage, but the average NB V12Gy increased by 48.9% when compared to the AVM‐VMAT plans. Agreement of point‐dose measurements with TPS calculations was −0.6% when averaged over all patients. Gamma analysis passing rates were above 90% for all film‐to‐film comparisons (2%/1 mm criteria), and for the film to TPS comparison (5%/1 mm). This work suggests that VMAT is capable of producing VS‐SRS plans with similar dose falloff characteristics as GK plans. NB dose depends on PTV margin size, and two‐stage treatment setups do not appear to contribute additional uncertainty to treatment delivery.
... The purpose of the stereotactic technique is to deposit accurately a high dose of radiation (in the sense of a biologically effective dose) to the target volume region-usually in one or more fractions, which is especially difficult with small tumors. 3, 4 Delivery of a very high dose causes complete destruction of tissues in irradiated volume. Therefore, the maximum protection of healthy tissues, which are located in close proximity to the tumor, plays an important role. ...
Introduction: Dosimetric verification of Intensity Modulation Radiotherapy treatment plans is usually carried out before the start of treatment. It is of special importance in the case of highly modulated plans, such as plans for patients in whom many tumors are irradiated simultaneously. In this work, we present the results of the verification of multi-target plans performed with the stereotactic HyperArc technique.
Material and methods: The results of dosimetric verification of 35 patient plans in the head are presented. The results are analyzed in terms of the number of tumors, and the distance of the tumor from the isocenter. Measurements were carried out with the film method. The gamma methodology was used (3%/2mm).
Results: The results showed a very good agreement between measurements and calculations.
Conclusions: No dependence of the verification result on the number of targets and the distance between the center of tumor and isocenter was found.
... High ablative doses of local radiation therapy (RT), often referred to as stereotactic radiosurgery (SRS) or stereotactic body radiotherapy (SBRT) is usually applied to tumors with limited size (5). The application of SRS or SBRT in bulky tumors is often considered challenging due to the difficulties in controlling toxicities of the surrounding normal/critical organs. ...
Although the combination of immune checkpoint blockades with high dose of radiation has indicated the potential of co-stimulatory effects, consistent clinical outcome has been yet to be demonstrated. Bulky tumors present challenges for radiation treatment to achieve high rate of tumor control due to large tumor sizes and normal tissue toxicities. As an alternative, spatially fractionated radiotherapy (SFRT) technique has been applied, in the forms of GRID or LATTICE radiation therapy (LRT), to safely treat bulky tumors. When used alone in a single or a few fractions, GRID or LRT can be best classified as palliative or tumor de-bulking treatments. Since only a small fraction of the tumor volume receive high dose in a SFRT treatment, even with the anticipated bystander effects, total tumor eradications are rare. Backed by the evidence of immune activation of high dose radiation, it is logical to postulate that the combination of High-Dose LATTICE radiation therapy (HDLRT) with immune checkpoint blockade would be effective and could subsequently lead to improved local tumor control without added toxicities, through augmenting the effects of radiation in-situ vaccine and T-cell priming. We herein present a case of non-small cell lung cancer (NSCLC) with multiple metastases. The patient received various types of palliative radiation treatments with combined chemotherapies and immunotherapies to multiple lesions. One of the metastatic lesions measuring 63.2 cc was treated with HDLRT combined with anti-PD1 immunotherapy. The metastatic mass regressed 77.84% over one month after the treatment, and had a complete local response (CR) five months after the treatment. No treatment-related side effects were observed during the follow-up exams. None of the other lesions receiving palliative treatments achieved CR. The dramatic differential outcome of this case lends support to the aforementioned postulate and prompts for further systemic clinical studies.
The TRS-483 Code of Practice (CoP) provides generic relative output correction factors, , for a range of detectors and beam energies as used in small field dosimetry. In this work, the convergence of the relative output factors (ROFs) for 6 MV X-ray beams with and without flattening filters was investigated under different combinations of beam collimation and published detector correction factors. The SFD, PFD and CC04 (IBA) were used to measure ROFs of a TrueBeam STx linear accelerator with small fields collimated by the high-definition MLC, which has 2.5 and 5.0 mm projected leaves. Two configurations were used for the collimators: (1) fixed jaws at 10 × 10 cm2 and (2) with a 2 mm offset from the MLC edge, in line with the recommended geometry from IROC-H as part of their auditing program and published dataset. The factors for the three detectors were taken from the TRS483 CoP and other published works. The average differences of ROFs measured by detectors under MLC fields with fixed jaws and with 2 mm jaws offset for the 6 MV-WFF beam are 1.4% and 1.9%, respectively. Similarly, they are 2.3% and 2.4% for the 6MV-FFF beam. The relative differences between the detector-average ROFs and the corresponding IROC-H dataset are 2.0% and 3.1% for the 6 MV-WFF beam, while they are 2.4% and 3.2% for the 6MV-FFF beam at the smallest available field size of 2 × 2 cm2. For smaller field sizes, the average ROFs of the three detectors and corresponding results from Akino and Dufreneix showed the largest difference to be 6.6% and 6.2% under the 6 MV-WFF beam, while they are 3.4% and 3.6% under the 6 MV-WFF beam at the smallest field size of 0.5 × 0.5 cm2. Some well-published specific output correction factors for different small field detector types give better convergence in the calculation of the relative output factor in comparison with the generic data provided by the TRS-483 CoP. Relative output factor measurements should be performed as close as possible to the clinical settings including a combination of collimation systems, beam types and using at least three different types of small field detector for more accurate computation of the treatment planning system. The IROC-H dataset is not available for field size smaller than 2 × 2 cm2 for double checks and so that user should carefully check with other publications with the same setting.
Purpose Good clinical practice in small field dosimetry relies on using multiple detectors for the determination of relative output factors (ROFs). The TRS-483 Code of Practice (CoP) provides recommended output correction factors, k, for a range of detectors and beam energies as used in small field dosimetry. In this work, the convergence of the ROFs for 6MV x-ray beams with and without flattening-filters were investigated under a different combinations of beam collimation and published detector correction factors.
Method Three IBA detectors SFD, PFD and CC04 were used to measure ROFs on a TrueBeam STx linear accelerator with small fields collimated by the high definition MLC which has 2.5 mm and 5.0 mm wide leaves. Two configurations were used for the collimators being 1) fixed-jaws at 10 × 10 cm2 and 2) with a 2 mm offset from the MLC edge, in line with the recommended geometry from IROC-H as part of their auditing program and published dataset. The k factors for the three detectors were taken from the TRS483 CoP and other published works.
Results The standard deviation in measured ROFs between detectors under 6MV-WFF beam are 1.4% and 1.9% while these under 6MV-FFF beam are 2.3% and 2.4% in MLC field with fixed-jaw and with 2 mm jaws-offset, respectively. The relative difference in averaged ROFs of three reference detectors from corresponding IROC-H dataset are 2.0% and 3.1% under 6MV-WFF beam while they are 2.4% and 3.2% under 6MV-FFF beam at the smallest available field size 2 × 2 cm2. For smaller field sizes, the uncertainty in averaged ROFs of three reference detectors from corresponding results of from 2 mm jaws-offset setting by Akino and Dufreneix showed the largest difference are 6.6% and 6.2% under 6MV-WFF beam while they are 3.4% and 3.6% under 6MVWFF beam at smallest field size 0.5 × 0.5 cm2.
Conclusion The corresponding datasets provided by TRS-483 and IROC-H are generic and may not statistically large enough with 6MV-FFF and also MLC field with 2 mm jaws-offset setting, so that clinical users should use at least three different types of small field detector in measurements. The IROC-H dataset is not available for field size smaller than 2 × 2 cm2 so that user should carefully check with other publications with the same setting.
Radiosurgery is a form of radiotherapy in which high dose of ionizing radiation, precisely guided with stereotactic method, is applied in a small tissue volume aiming surgery-like effect. This method is used for treatment of some primary tumors and their metastases as well as for some non-oncological processes. Radiosurgery can be performed on Gamma Knife, CyberKnife, Helical tomotherapy and other contemporary linear accelerators and accelerators of protons and heavy ions. This article presents the Gamma Knife which is the first ever radiosurgery device. It was developed specifically for intracranial applications and is used for the treatment of malignant tumors, metastases, benign tumors, vascular and functional brain disorders and is widely accepted as "gold standard" in cranial radiosurgery. Also presented are the new technological features of and clinical possibilities with the newest Gamma Knife model-ICON, which is already available and in clinical operation in Bulgaria.
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