Array ( [0] => {{Short description|Surgical Specialty}}{{About|the medical procedure|the album by American rock band New Found Glory|Radiosurgery (album)}} [1] => {{Infobox medical intervention [2] => | name = Radiosurgery [3] => | synonym = [4] => | image =Intraoperative photograph showing a radiosurgery system.png [5] => | caption =Intraoperative photograph showing a radiosurgery system being positioned. The patient in the photo is being treated for rectal cancer. [6] => | alt = [7] => | pronounce = [8] => | specialty = [[Oncology]] / [[Neurosurgery]] [9] => | synonyms = [10] => | ICD10 = [11] => | ICD9 = [12] => | ICD9unlinked = [13] => | CPT = [14] => | MeshID = [15] => | LOINC = [16] => | other_codes = [17] => | MedlinePlus =007577 [18] => | eMedicine =1423298 [19] => }} [20] => '''Radiosurgery''' is [[surgery]] using [[radiation]],{{Citation |author=Elsevier |author-link=Elsevier |title=Dorland's Illustrated Medical Dictionary |publisher=Elsevier |url=http://dorlands.com/ |postscript=.}} that is, the destruction of precisely selected areas of [[tissue (biology)|tissue]] using [[ionizing radiation]] rather than excision with a blade. Like other forms of [[radiation therapy]] (also called radiotherapy), it is usually used to treat [[cancer]]. Radiosurgery was originally defined by the Swedish neurosurgeon [[Lars Leksell]] as "a single high dose fraction of radiation, stereotactically directed to an intracranial region of interest".{{cite journal | vauthors = Leksell L | title = The stereotaxic method and radiosurgery of the brain | journal = Acta Chirurgica Scandinavica | volume = 102 | issue = 4 | pages = 316–319 | date = December 1951 | pmid = 14914373 }} [21] => [22] => In '''stereotactic radiosurgery''' ('''SRS'''), the word "[[stereotactic surgery|stereotactic]]" refers to a three-dimensional [[coordinate system]] that enables accurate correlation of a virtual target seen in the patient's diagnostic images with the actual target position in the patient. Stereotactic radiosurgery may also be called [[stereotactic radiation therapy|stereotactic body radiation therapy]] (SBRT) or stereotactic ablative radiotherapy (SABR) when used outside the [[central nervous system]] (CNS). [23] => [24] => ==History== [25] => Stereotactic radiosurgery was first developed in 1949 by the Swedish neurosurgeon Lars Leksell to treat small targets in the brain that were not amenable to conventional surgery. The initial stereotactic instrument he conceived used probes and electrodes.{{cite journal| vauthors = Leksell L |title=A stereotaxic apparatus for intracerebral surgery|journal=Acta Chirurgica Scandinavica|year=1949|volume=99|pages=229}} The first attempt to supplant the electrodes with radiation was made in the early fifties, with [[x-ray]]s.{{cite journal | vauthors = Leksell L | title = The stereotaxic method and radiosurgery of the brain | journal = Acta Chirurgica Scandinavica | volume = 102 | issue = 4 | pages = 316–319 | date = December 1951 | pmid = 14914373 }} The principle of this instrument was to hit the intra-cranial target with narrow beams of radiation from multiple directions. The beam paths converge in the target volume, delivering a lethal cumulative dose of radiation there, while limiting the dose to the adjacent healthy tissue. Ten years later significant progress had been made, due in considerable measure to the contribution of the physicists Kurt Liden and Börje Larsson.{{cite journal | vauthors = Larsson B, Leksell L, Rexed B, Sourander P, Mair W, Andersson B | title = The high-energy proton beam as a neurosurgical tool | journal = Nature | volume = 182 | issue = 4644 | pages = 1222–1223 | date = November 1958 | pmid = 13590280 | doi = 10.1038/1821222a0 | s2cid = 4163683 | bibcode = 1958Natur.182.1222L }} At this time, stereotactic [[proton]] beams had replaced the x-rays.{{cite journal | vauthors = Leksell L, Larsson B, Andersson B, Rexed B, Sourander P, Mair W | title = Lesions in the depth of the brain produced by a beam of high energy protons | journal = Acta Radiologica | volume = 54 | issue = 4 | pages = 251–264 | date = October 1960 | pmid = 13760648 | doi = 10.3109/00016926009172547 | doi-access = free }} The heavy particle beam presented as an excellent replacement for the surgical knife, but the [[synchrocyclotron]] was too clumsy. Leksell proceeded to develop a practical, compact, precise and simple tool which could be handled by the surgeon himself. In 1968 this resulted in the Gamma Knife, which was installed at the [[Karolinska Institutet|Karolinska Institute]] and consisted of several [[cobalt-60]] [[radioactivity|radioactive]] sources placed in a kind of helmet with central channels for irradiation with gamma rays.{{cite journal | vauthors = Leksell L | title = Stereotactic radiosurgery | journal = Journal of Neurology, Neurosurgery, and Psychiatry | volume = 46 | issue = 9 | pages = 797–803 | date = September 1983 | pmid = 6352865 | pmc = 1027560 | doi = 10.1136/jnnp.46.9.797 }} This prototype was designed to produce slit-like radiation lesions for functional neurosurgical procedures to treat pain, movement disorders, or behavioral disorders that did not respond to conventional treatment. The success of this first unit led to the construction of a second device, containing 179 cobalt-60 sources. This second Gamma Knife unit was designed to produce spherical lesions to treat brain tumors and intracranial [[arteriovenous malformation]]s (AVMs).{{cite journal | vauthors = Wu A, Lindner G, Maitz AH, Kalend AM, Lunsford LD, Flickinger JC, Bloomer WD | title = Physics of gamma knife approach on convergent beams in stereotactic radiosurgery | journal = International Journal of Radiation Oncology, Biology, Physics | volume = 18 | issue = 4 | pages = 941–949 | date = April 1990 | pmid = 2182583 | doi = 10.1016/0360-3016(90)90421-f }} Additional units were installed in the 1980s all with 201 cobalt-60 sources.{{cite journal | vauthors = Walton L, Bomford CK, Ramsden D | title = The Sheffield stereotactic radiosurgery unit: physical characteristics and principles of operation | journal = The British Journal of Radiology | volume = 60 | issue = 717 | pages = 897–906 | date = September 1987 | pmid = 3311273 | doi = 10.1259/0007-1285-60-717-897 }} [26] => [27] => In parallel to these developments, a similar approach was designed for a [[linear particle accelerator]] or Linac. Installation of the first 4 [[electronvolt|MeV]] clinical linear accelerator began in June 1952 in the Medical Research Council (MRC) Radiotherapeutic Research Unit at the [[Hammersmith Hospital]], London.{{cite journal | vauthors = Fry DW, R-Shersby-Harvie RB | title = A traveling-wave linear accelerator for 4-MeV. electrons | journal = Nature | volume = 162 | issue = 4126 | pages = 859–861 | date = November 1948 | pmid = 18103121 | doi = 10.1038/162859a0 | s2cid = 4075004 | bibcode = 1948Natur.162..859F }} The system was handed over for physics and other testing in February 1953 and began to treat patients on 7 September that year. Meanwhile, work at the Stanford Microwave Laboratory led to the development of a 6 MeV accelerator, which was installed at Stanford University Hospital, California, in 1956.{{cite journal | vauthors = Bernier J, Hall EJ, Giaccia A | title = Radiation oncology: a century of achievements | journal = Nature Reviews. Cancer | volume = 4 | issue = 9 | pages = 737–747 | date = September 2004 | pmid = 15343280 | doi = 10.1038/nrc1451 | s2cid = 12382751 }} Linac units quickly became favored devices for conventional fractionated [[radiation therapy|radiotherapy]] but it lasted until the 1980s before dedicated Linac radiosurgery became a reality. In 1982, the Spanish neurosurgeon J. Barcia-Salorio began to evaluate the role of cobalt-generated and then Linac-based photon radiosurgery for the treatment of AVMs and [[epilepsy]].{{cite journal | vauthors = Barcia-Salorio JL, Herandez G, Broseta J, Gonzalez-Darder J, Ciudad J | title = Radiosurgical treatment of carotid-cavernous fistula | journal = Applied Neurophysiology | volume = 45 | issue = 4–5 | pages = 520–522 | year = 1982 | pmid = 7036892 | doi = 10.1159/000101675 }} In 1984, Betti and Derechinsky described a Linac-based radiosurgical system.{{Cite book| vauthors = Betti OO |title=Advances in Stereotactic and Functional Neurosurgery 6 |chapter=Hyperselective Encephalic Irradiation with Linear Accelerator|journal=[[Acta Neurochirurgica Supplement]] |year=1984|volume=33|pages=385–390|doi=10.1007/978-3-7091-8726-5_60|isbn=978-3-211-81773-5}} Winston and Lutz further advanced Linac-based radiosurgical prototype technologies by incorporating an improved stereotactic positioning device and a method to measure the accuracy of various components.{{cite journal | vauthors = Winston KR, Lutz W | title = Linear accelerator as a neurosurgical tool for stereotactic radiosurgery | journal = Neurosurgery | volume = 22 | issue = 3 | pages = 454–464 | date = March 1988 | pmid = 3129667 | doi = 10.1227/00006123-198803000-00002 }} Using a modified Linac, the first patient in the United States was treated in Boston [[Brigham and Women's Hospital]] in February 1986.{{cn|date=December 2021}} [28] => [29] => ===21st century=== [30] => Technological improvements in medical imaging and computing have led to increased clinical adoption of stereotactic radiosurgery and have broadened its scope in the 21st century.{{Cite book| vauthors = De Salles A |title=Reconstructive Neurosurgery|chapter=Radiosurgery from the brain to the spine: 20 years experience|journal=[[Acta Neurochirurgica. Supplement]] |year=2008|volume=101|pages=163–168|pmid=18642653|doi=10.1007/978-3-211-78205-7_28|series=Acta Neurochirurgica Supplementum|isbn=978-3-211-78204-0}}{{cite journal | vauthors = Timmerman R, McGarry R, Yiannoutsos C, Papiez L, Tudor K, DeLuca J, Ewing M, Abdulrahman R, DesRosiers C, Williams M, Fletcher J | display-authors = 6 | title = Excessive toxicity when treating central tumors in a phase II study of stereotactic body radiation therapy for medically inoperable early-stage lung cancer | journal = Journal of Clinical Oncology | volume = 24 | issue = 30 | pages = 4833–4839 | date = October 2006 | pmid = 17050868 | doi = 10.1200/JCO.2006.07.5937 | doi-access = free }} The localization accuracy and precision that are implicit in the word "stereotactic" remain of utmost importance for radiosurgical interventions and are significantly improved via [[image-guided surgery|image-guidance]] technologies such as the [[N-localizer]]{{cite book | vauthors = Galloway Jr RL | veditors = Golby AJ | title = Image-Guided Neurosurgery | chapter = Introduction and Historical Perspectives on Image-Guided Surgery | pages = 2–4 | publisher = Elsevier | location = Amsterdam | year = 2015 | isbn=978-0-12-800870-6|doi=10.1016/B978-0-12-800870-6.00001-7}} and Sturm-Pastyr localizer{{cite journal | vauthors = Sturm V, Pastyr O, Schlegel W, Scharfenberg H, Zabel HJ, Netzeband G, Schabbert S, Berberich W | display-authors = 6 | title = Stereotactic computer tomography with a modified Riechert-Mundinger device as the basis for integrated stereotactic neuroradiological investigations | journal = Acta Neurochirurgica | volume = 68 | issue = 1–2 | pages = 11–17 | year = 1983 | pmid = 6344559 | doi = 10.1007/BF01406197 | s2cid = 38864553 }} that were originally developed for [[stereotactic surgery]]. [31] => [32] => In the 21st century the original concept of radiosurgery expanded to include treatments comprising up to five [[Dose fractionation|fractions]], and stereotactic radiosurgery has been redefined as a distinct [[neurosurgical]] discipline that utilizes externally generated [[ionizing radiation]] to inactivate or eradicate defined targets, typically in the head or spine, without the need for a surgical incision.{{cite journal | vauthors = Barnett GH, Linskey ME, Adler JR, Cozzens JW, Friedman WA, Heilbrun MP, Lunsford LD, Schulder M, Sloan AE | display-authors = 6 | title = Stereotactic radiosurgery--an organized neurosurgery-sanctioned definition | journal = Journal of Neurosurgery | volume = 106 | issue = 1 | pages = 1–5 | date = January 2007 | pmid = 17240553 | doi = 10.3171/jns.2007.106.1.1 | s2cid = 1007105 }} Irrespective of the similarities between the concepts of stereotactic radiosurgery and fractionated radiotherapy the mechanism to achieve treatment is subtly different, although both treatment modalities are reported to have identical outcomes for certain indications.{{cite journal | vauthors = Combs SE, Welzel T, Schulz-Ertner D, Huber PE, Debus J | title = Differences in clinical results after LINAC-based single-dose radiosurgery versus fractionated stereotactic radiotherapy for patients with vestibular schwannomas | journal = International Journal of Radiation Oncology, Biology, Physics | volume = 76 | issue = 1 | pages = 193–200 | date = January 2010 | pmid = 19604653 | doi = 10.1016/j.ijrobp.2009.01.064 }} Stereotactic radiosurgery has a greater emphasis on delivering precise, high doses to small areas, to destroy target tissue while preserving adjacent normal tissue. The same principle is followed in conventional radiotherapy although lower dose rates spread over larger areas are more likely to be used (for example as in [[Radiation therapy#Volumetric modulated arc therapy (VMAT)|VMAT]] treatments). Fractionated radiotherapy relies more heavily on the different [[radiosensitivity]] of the target and the surrounding normal tissue to the [[Absorbed dose|total accumulated radiation dose]]. Historically, the field of fractionated radiotherapy evolved from the original concept of stereotactic radiosurgery following discovery of the principles of [[radiobiology]]: repair, reassortment, repopulation, and reoxygenation.{{cite journal | vauthors = Bernier J, Hall EJ, Giaccia A | title = Radiation oncology: a century of achievements | journal = Nature Reviews. Cancer | volume = 4 | issue = 9 | pages = 737–747 | date = September 2004 | pmid = 15343280 | doi = 10.1038/nrc1451 | s2cid = 12382751 }} Today, both treatment techniques are complementary, as tumors that may be resistant to fractionated radiotherapy may respond well to radiosurgery, and tumors that are too large or too close to critical organs for safe radiosurgery may be suitable candidates for fractionated radiotherapy. [33] => [34] => Today, both Gamma Knife and Linac radiosurgery programs are commercially available worldwide. While the Gamma Knife is dedicated to radiosurgery, many Linacs are built for conventional fractionated radiotherapy and require additional technology and expertise to become dedicated radiosurgery tools. There is not a clear difference in efficacy between these different approaches.{{cite report |url= http://eprints.hta.lbg.ac.at/901/ |title=Gamma Knife versus adapted linear accelerators: A comparison of two radiosurgical applications | vauthors = Mathis S, Eisner W |date=6 October 2010 |issn=1993-0488|eissn=1993-0496|series=HTA-Projektbericht 47}}{{cite book | vauthors = McDermott MW |title=Radiosurgery |date=2010 |publisher=Karger Medical and Scientific Publishers |isbn=9783805593656 |page=196 |url=https://books.google.com/books?id=Ya86AQAAQBAJ&pg=PA196 |language=en}} The major manufacturers, [[Varian Medical Systems|Varian]] and [[Elekta]] offer dedicated radiosurgery Linacs as well as machines designed for conventional treatment with radiosurgery capabilities. Systems designed to complement conventional Linacs with beam-shaping technology, treatment planning, and image-guidance tools to provide.{{cite book | vauthors = Schoelles KM, Uhl S, Launders J, Inamdar R, Bruening W, Sullivan N, Tipton KN |title=Stereotactic Body Radiation Therapy |date=2011 |publisher=Agency for Healthcare Research and Quality (US) |chapter-url=https://www.ncbi.nlm.nih.gov/books/NBK55712/ |language=en |chapter=Currently Marketed Devices for SBRT |pmid=21735562}} An example of a dedicated radiosurgery Linac is the [[Cyberknife (device)|CyberKnife]], a compact Linac mounted onto a robotic arm that moves around the patient and irradiates the tumor from a large set of fixed positions, thereby mimicking the Gamma Knife concept. [35] => [36] => ==Mechanism of action== [37] => [[Image:Acoustic schwannoma gamma knife.jpg|right|thumb|Planning [[CT scan]] with IV contrast in a patient with left cerebellopontine angle [[vestibular schwannoma]]]] [38] => The fundamental principle of radiosurgery is that of selective [[ionization]] of tissue, by means of high-energy beams of radiation. Ionization is the production of [[ion]]s and [[free radicals]] which are damaging to the [[cell (biology)|cells]]. These ions and radicals, which may be formed from the water in the cell or biological materials, can produce irreparable damage to DNA, proteins, and lipids, resulting in the cell's death. Thus, biological inactivation is carried out in a volume of tissue to be treated, with a precise destructive effect. The radiation dose is usually measured in [[Gray (unit)|grays]] (one gray (Gy) is the absorption of one [[joule]] of energy per kilogram of mass). A unit that attempts to take into account both the different organs that are irradiated and the type of radiation is the [[sievert]], a unit that describes both the amount of energy deposited and the biological effectiveness.{{cn|date=December 2021}} [39] => ==Clinical applications== [40] => When used outside the CNS it may be called stereotactic body radiation therapy (SBRT) or stereotactic ablative radiotherapy (SABR).{{Cite web|url=https://www.cancerresearchuk.org/about-cancer/cancer-in-general/treatment/radiotherapy/external/types/stereotactic-body-radiotherapy-sbrt|title=Stereotactic radiotherapy | Cancer treatment | Cancer Research UK|website=www.cancerresearchuk.org}} [41] => [42] => ===Brain and spine=== [43] => Radiosurgery is performed by a multidisciplinary team of [[neurosurgeons]], [[radiation oncologist]]s and medical [[physicist]]s to operate and maintain highly sophisticated, highly precise and complex instruments, including medical linear accelerators, the Gamma Knife unit and the Cyberknife unit. The highly precise irradiation of targets within the brain and spine is planned using information from medical images that are obtained via [[computed tomography]], [[magnetic resonance imaging]], and [[angiography]].{{cn|date=December 2021}} [44] => [45] => Radiosurgery is indicated primarily for the therapy of tumors, vascular lesions and functional disorders. Significant clinical judgment must be used with this technique and considerations must include lesion type, pathology if available, size, location and age and general health of the patient. General contraindications to radiosurgery include excessively large size of the target lesion, or lesions too numerous for practical treatment. Patients can be treated within one to five days as [[outpatient]]s. By comparison, the average hospital stay for a [[craniotomy]] (conventional neurosurgery, requiring the opening of the skull) is about 15 days. The radiosurgery outcome may not be evident until months after the treatment. Since radiosurgery does not remove the tumor but inactivates it biologically, lack of growth of the lesion is normally considered to be treatment success. General indications for radiosurgery include many kinds of brain tumors, such as [[acoustic neuroma]]s, [[germinoma]]s, [[meningioma]]s, [[metastases]], trigeminal neuralgia, arteriovenous malformations, and skull base tumors, among others. [46] => [47] => Stereotatic radiosurgery of the spinal metastasis is efficient in controlling pain in up to 90% of the cases and ensures stability of the tumours on imaging evaluation in 95% of the cases, and is more efficient for spinal metastasis involving one or two segments. Meanwhile, conventional external beam radiotherapy is more suitable for multiple spinal involvement.{{cite journal | vauthors = Joaquim AF, Ghizoni E, Tedeschi H, Pereira EB, Giacomini LA | title = Stereotactic radiosurgery for spinal metastases: a literature review | journal = Einstein (Sao Paulo) | volume = 11 | issue = 2 | pages = 247–255 | date = June 2013 | pmid = 23843070 | pmc = 4872903 | doi = 10.1590/S1679-45082013000200020 }} [48] => [49] => === Combination therapy === [50] => SRS may be administered alone or in combination with other therapies. For brain metastases, these treatment options include [[Whole-brain radiation|whole brain radiation therapy]] (WBRT), surgery, and systemic therapies. However, a recent systematic review found no difference in the affects on overall survival or deaths due to brain metastases when comparing SRS treatment alone to SRS plus WBRT treatment or WBRT alone.{{Cite web |title=Radiation Therapy for Brain Metastases {{!}} Effective Health Care (EHC) Program |url=https://effectivehealthcare.ahrq.gov/products/radiation-therapy-brain-metastases/research |access-date=2023-10-24 |website=effectivehealthcare.ahrq.gov |language=en}} [51] => [52] => ===Other bodily organs=== [53] => Expansion of stereotactic radiotherapy to other lesions is increasing, and includes liver cancer, lung cancer, pancreatic cancer, etc.{{citation needed|date=December 2022}} [54] => [55] => ==Risks== [56] => ''[[The New York Times]]'' reported in December 2010 that radiation overdoses had occurred with the linear accelerator method of radiosurgery, due in large part to inadequate safeguards in equipment retrofitted for stereotactic radiosurgery.{{cite news | url = https://www.nytimes.com/2010/12/29/health/29radiation.html | title = A Pinpoint Beam Strays Invisibly, Harming Instead of Healing | work = [[The New York Times]] | date = 2010-12-28}} In the U.S. the [[Food and Drug Administration]] (FDA) regulates these devices, whereas the Gamma Knife is regulated by the [[Nuclear Regulatory Commission]]. [57] => [58] => This is evidence that [[Cancer immunotherapy|immunotherapy]] may be useful for treatment of radiation necrosis following stereotactic radiotherapy.{{cite journal | vauthors = Kaidar-Person O, Zagar TM, Deal A, Moschos SJ, Ewend MG, Sasaki-Adams D, Lee CB, Collichio FA, Fried D, Marks LB, Chera BS | display-authors = 6 | title = The incidence of radiation necrosis following stereotactic radiotherapy for melanoma brain metastases: the potential impact of immunotherapy | journal = Anti-Cancer Drugs | volume = 28 | issue = 6 | pages = 669–675 | date = July 2017 | pmid = 28368903 | doi = 10.1097/CAD.0000000000000497 | s2cid = 3560210 }} [59] => [60] => == Types of radiation source == [61] => The selection of the proper kind of radiation and device depends on many factors including lesion type, size, and location in relation to critical structures. Data suggest that similar clinical outcomes are possible with all of the various techniques. More important than the device used are issues regarding indications for treatment, total dose delivered, fractionation schedule and conformity of the treatment plan.{{cn|date=December 2021}} [62] => [63] => === Gamma Knife === [64] => {{Redirect|Gamma Knife|the album by Kayo Dot|Gamma Knife (album){{!}}''Gamma Knife'' (album)|the song by King Gizzard & the Lizard Wizard|Gamma Knife (song){{!}}"Gamma Knife" (song)}} [65] => [[File:Dr. B. K. Misra performing Stereotactic Gamma Radiosurgery.jpg|thumb|A doctor performing Gamma Knife Radiosurgery]] [66] => [[Image:Gamma Knife Graphic.jpg|thumb|[[Nuclear Regulatory Commission|NRC]] graphic of the Leksell Gamma Knife]] [67] => A Gamma Knife (also known as the Leksell Gamma Knife) is used to treat [[brain tumors]] by administering high-intensity gamma radiation therapy in a manner that concentrates the radiation over a small volume. The device was invented in 1967 at the Karolinska Institute in [[Stockholm]], Sweden, by [[Lars Leksell]], Romanian-born neurosurgeon Ladislau Steiner, and [[radiobiologist]] Börje Larsson from [[Uppsala University]], Sweden. [68] => [69] => A Gamma Knife typically contains 201 [[cobalt-60]] sources of approximately 30 [[Curie (unit)|curie]]s each (1.1 [[terabecquerel|TBq]]), placed in a hemispheric array in a heavily [[Radiation protection|shielded]] assembly. The device aims [[gamma ray|gamma radiation]] through a target point in the patient's brain. The patient wears a specialized helmet that is surgically fixed to the skull, so that the brain tumor remains stationary at the target point of the gamma rays. An [[ablation|ablative]] dose of radiation is thereby sent through the tumor in one treatment session, while surrounding brain tissues are relatively spared. [70] => [71] => Gamma Knife therapy, like all radiosurgery, uses doses of radiation to kill cancer cells and shrink tumors, delivered precisely to avoid damaging healthy brain tissue. Gamma Knife radiosurgery is able to accurately focus many beams of gamma radiation on one or more tumors. Each individual beam is of relatively low intensity, so the radiation has little effect on intervening brain tissue and is concentrated only at the tumor itself. [72] => [73] => Gamma Knife radiosurgery has proven effective for patients with benign or malignant brain tumors up to {{cvt|4|cm|inch}} in size, [[Blood vessel|vascular]] malformations such as an [[arteriovenous malformation]] (AVM), pain, and other functional problems.{{cite journal | vauthors = Régis J, Bartolomei F, Hayashi M, Chauvel P | title = What role for radiosurgery in mesial temporal lobe epilepsy | journal = Zentralblatt für Neurochirurgie | volume = 63 | issue = 3 | pages = 101–105 | year = 2002 | pmid = 12457334 | doi = 10.1055/s-2002-35824 }}{{cite journal | vauthors = Kwon Y, Whang CJ | title = Stereotactic Gamma Knife radiosurgery for the treatment of dystonia | journal = Stereotactic and Functional Neurosurgery | volume = 64 | issue = Suppl 1 | pages = 222–227 | year = 1995 | pmid = 8584831 | doi = 10.1159/000098782 }}{{cite journal | vauthors = Donnet A, Valade D, Régis J | title = Gamma knife treatment for refractory cluster headache: prospective open trial | journal = Journal of Neurology, Neurosurgery, and Psychiatry | volume = 76 | issue = 2 | pages = 218–221 | date = February 2005 | pmid = 15654036 | pmc = 1739520 | doi = 10.1136/jnnp.2004.041202 }}{{cite journal | vauthors = Herman JM, Petit JH, Amin P, Kwok Y, Dutta PR, Chin LS | title = Repeat gamma knife radiosurgery for refractory or recurrent trigeminal neuralgia: treatment outcomes and quality-of-life assessment | journal = International Journal of Radiation Oncology, Biology, Physics | volume = 59 | issue = 1 | pages = 112–116 | date = May 2004 | pmid = 15093906 | doi = 10.1016/j.ijrobp.2003.10.041 }} For treatment of trigeminal neuralgia the procedure may be used repeatedly on patients. [74] => [75] => Acute complications following Gamma Knife radiosurgery are rare,{{cite journal | vauthors = Chin LS, Lazio BE, Biggins T, Amin P | title = Acute complications following gamma knife radiosurgery are rare | journal = Surgical Neurology | volume = 53 | issue = 5 | pages = 498–502; discussion 502 | date = May 2000 | pmid = 10874151 | doi = 10.1016/S0090-3019(00)00219-6 }} and complications are related to the condition being treated.{{cite journal | vauthors = Stafford SL, Pollock BE, Foote RL, Link MJ, Gorman DA, Schomberg PJ, Leavitt JA | title = Meningioma radiosurgery: tumor control, outcomes, and complications among 190 consecutive patients | journal = Neurosurgery | volume = 49 | issue = 5 | pages = 1029–37; discussion 1037–8 | date = November 2001 | pmid = 11846894 | doi = 10.1097/00006123-200111000-00001 | s2cid = 13646182 }}{{cite journal | vauthors = Cho DY, Tsao M, Lee WY, Chang CS | title = Socioeconomic costs of open surgery and gamma knife radiosurgery for benign cranial base tumors | journal = Neurosurgery | volume = 58 | issue = 5 | pages = 866–73; discussion 866–73 | date = May 2006 | pmid = 16639320 | doi = 10.1227/01.NEU.0000209892.42585.9B | s2cid = 38660074 }} [76] => [77] => === Linear accelerator-based therapies === [78] => {{Main|Megavoltage X-rays}} [79] => [80] => A linear accelerator (linac) produces x-rays from the impact of accelerated electrons striking a high ''z'' target, usually tungsten. The process is also referred to as "x-ray therapy" or "photon therapy." The emission head, or "[[Gantry crane|gantry]]", is mechanically rotated around the patient in a full or partial circle. The table where the patient is lying, the "couch", can also be moved in small linear or angular steps. The combination of the movements of the gantry and of the couch allow the computerized planning of the volume of tissue that is going to be irradiated. Devices with a high energy of 6 MeV are commonly used for the treatment of the brain, due to the depth of the target. The diameter of the energy beam leaving the emission head can be adjusted to the size of the lesion by means of [[collimator]]s. They may be interchangeable orifices with different diameters, typically varying from 5 to 40 mm in 5 mm steps, or multileaf collimators, which consist of a number of metal leaflets that can be moved dynamically during treatment in order to shape the radiation beam to conform to the mass to be ablated. {{As of|2017}} Linacs were capable of achieving extremely narrow beam geometries, such as 0.15 to 0.3 mm. Therefore, they can be used for several kinds of surgeries which hitherto had been carried out by open or endoscopic surgery, such as for trigeminal neuralgia. Long-term follow-up data has shown it to be as effective as radiofrequency ablation, but inferior to surgery in preventing the recurrence of pain.{{cn|date=December 2021}} [81] => [82] => The first such systems were developed by [[John R. Adler]], a [[Stanford University]] professor of neurosurgery and radiation oncology, and Russell and Peter Schonberg at Schonberg Research, and commercialized under the brand name CyberKnife. [83] => [84] => === Proton beam therapy === [85] => {{Main|Proton therapy}} [86] => [87] => Protons may also be used in radiosurgery in a procedure called '''Proton Beam Therapy''' (PBT) or [[proton therapy]]. Protons are extracted from proton donor materials by a medical [[synchrotron]] or [[cyclotron]], and accelerated in successive transits through a circular, evacuated conduit or cavity, using powerful magnets to shape their path, until they reach the energy required to just traverse a human body, usually about 200 MeV. They are then released toward the region to be treated in the patient's body, the irradiation target. In some machines, which deliver protons of only a specific energy, a custom mask made of plastic is interposed between the beam source and the patient to adjust the beam energy to provide the appropriate degree of penetration. The phenomenon of the [[Bragg peak]] of ejected protons gives proton therapy advantages over other forms of radiation, since most of the proton's energy is deposited within a limited distance, so tissue beyond this range (and to some extent also tissue inside this range) is spared from the effects of radiation. This property of protons, which has been called the "[[depth charge]] effect" by analogy to the explosive weapons used in anti-submarine warfare, allows for conformal dose distributions to be created around even very irregularly shaped targets, and for higher doses to targets surrounded or backstopped by radiation-sensitive structures such as the [[optic chiasm]] or brainstem. The development of "intensity modulated" techniques allowed similar conformities to be attained using linear accelerator radiosurgery.{{cn|date=December 2021}} [88] => [89] => {{As of|2013}} there was no evidence that proton beam therapy is better than any other types of treatment in most cases, except for a "handful of rare pediatric cancers". Critics, responding to the increasing number of very expensive PBT installations, spoke of a "medical [[arms race]]" and "crazy medicine and unsustainable public policy".{{cite web |url=http://www.medscape.com/viewarticle/778466 |title=Uncertainty About Proton-Beam Radiotherapy Lingers |website=Medscape|date=30 January 2013 |author=Roxanne Nelson |access-date= 22 March 2017}} [90] => [91] => == References == [92] => {{Reflist}} [93] => [94] => == External links == [95] => * [https://link.springer.com/book/10.1007/978-3-540-69886-9 Treating Tumors that Move with Respiration] Book on Radiosurgery to moving targets (July 2007) [96] => * [https://link.springer.com/book/10.1007/978-3-642-11151-8 Shaped Beam Radiosurgery] Book on LINAC-based radiosurgery using multileaf collimation (March 2011) [97] => [98] => {{Nuclear Technology}} [99] => {{Radiation oncology}} [100] => {{Authority control}} [101] => [102] => [[Category:Neurology procedures]] [103] => [[Category:Radiobiology]] [104] => [[Category:Radiation therapy procedures]] [105] => [[Category:Neurosurgery]] [] => )
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Radiosurgery

Radiosurgery is surgery using radiation, that is, the destruction of precisely selected areas of tissue using ionizing radiation rather than excision with a blade. Like other forms of radiation therapy (also called radiotherapy), it is usually used to treat cancer.

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