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Extracranial Stereotactic Radiosurgery






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Extracranial Stereotactic Radiosurgery Extracranial Stereotactic Radiosurgery Document Transcript

  • Stereotactic Radiosurgery Extracranial Stereotactic Using stereotactic techniques, give a lethal dose of ionizing radiation to the target, Radiosurgery while minimizing the toxic radiation to Annette Quinn, MSN, RN the surrounding tissue Program Manager, University of = Pittsburgh Medical Center High doses of radiation to defined target volumes Basic technique Linear accelerators• Multiple radiation • Various systems: beams converge on the – X-knife® lesion – Novalis®• At the intersection a – Cyberknife® high dose is delivered, – Trilogy® while the surrounding – Synergy® tissue receives a minimal dose Linear accelerator-based SRS Indications of SRS• Frame based: • Cells with neoplastic growth (benign and – X-knife malignant) – Novalis • Vascular malformation• Frameless: • Lesionectomy: Functional Neurosurgery – Cyberknife (trigeminal neuralgia) – Trilogy – Synergy 1
  • Historical notes • Accuray founded in 1992 Cyberknife® Radiosurgery • First patient treated in 1994 • CyberKnife System FDA Clearance – August 2001 “To provide treatment planning and image-guided radiosurgery and precision radiotherapy for lesions, tumors, and conditions anywhere in the body when radiation treatment is indicated.” CyberKnife System • The CyberKnife® is a lightweight linear accelerator mounted on a robotic arm. • Does not rely on a fixed, invasive frame to keep the target Slide not available organ immobile, thus can be used throughout the body • Two ceiling mounted cameras perform near real-time image tracking with 1 mm spatial accuracy. • The robot relates the identified lesion to radiographic landmarks (the patient’s skull). Advantage of the Cyberknife CyberKnife• “Frameless” technique does not affect • 6 MeV linac mounted on robot arm- 6 degrees of rotation accuracy but allows for extracranial targeting • 100 treatment positions (nodes) with the possibility to use 1, 200 intersecting beams of radiation• Ability to fractionate treatment allows treatment of lesions abutting or involving • 2 cross-firing X-ray cameras monitor patient position radio-sensitive structures like the optic apparatus • Robot corrects for patient motion 2
  • CyberKnife CyberKnife Treatment (cont.) • Continuously monitors and corrects for • Radiosurgery in early days was only changes in patient position and motion by performed with single high doses of comparing pretreatment CT-based digitally radiation. reconstructed radiographs (DRR’s) to • In contrast benefit of fractionation is well digital radiographs acquired throughout the established in general radiotherapy radiosurgical treatment. • CyberKnife’s capability to treat without head ring and to treat extracranial lesions • Adjusts the position of the robotically has created a pathway for fractionation targeted accelerator accordingly Process Treatment Set-up • Once the fiducials have been implanted the • Technology can compensate for minimal treatment process consists of three basic movements, larger patient movements are steps limited by fitting the patient with an • 1) Treatment set-up, immobilization device. A custom-fit, • 2) Treatment planning, flexible mesh mask (for head/neck treatments) or body cradle is formed and is • 3) Treatment delivery used to help minimize movement during the treatment and ensures patient comfortImmobilization for intracranial (or head & neck) lesions Immobilization for extracranial lesions Image not available Image not available 3
  • What is a fiducial? Fiducials (cont.)• Frameless radiosurgery allows ablation of tumors • For targets outside the skull there is a need anywhere within the body to define an intermediate spatial reference• For intracranial lesions a comparison between bony profiles from DRRs and x-ray images is system that is visible in CT and in employed to position patient. conventional X-ray.• Match the bony skull based landmarks from CT- • For this purpose before CT scanning 3-6 based DRRs to those captured by the orthogonal gold fiducials are inserted in or around the pair of digital X-ray images tumor• Patient repostioned until perfect match is made. Fiducial Placement Image acquisition Image not available Image not available Treatment Planning Treatment Delivery• Inverse treatment planning: Clinician • Occurs 1-5 days after planning specifies the total dose to be delivered to the • Patient fitted with immobilization device tumor and sets boundaries to protect the • imaging system acquires digital x-rays of the patient position. critical structures. The software then • information is used to move the linear accelerator determines the targeting positions and dose to the appropriate position to be delivered from a particular targeting • robot moves and re-targets the linear accelerator at position. a large number of positions around the patient. At each position or “node”, a small radiation beam is delivered. 4
  • Treatment Delivery (cont) The Cyberknife “Team”• This process is repeated at 50 to 300 different positions around the patient to complete the • Radiation Oncologist treatment. • Neurosurgeon/surgeon• The entire process is painless and typically takes • Physicist between 30 to 120 minutes to deliver all radiation • Medical Oncologist beams depending on tumor location. • Nurse• Most typically a patient can go home immediately • Radiation Therapist upon completion and return to normal activities Treatment Planning System Image not available Alignment Screen Unlimited Potential • Instrument expands far beyond current 1,200 beams (targeting Image not available positions and approach angles) • System utilizes CT and MRI scans for treatment planning 5
  • CyberKnife Clinical Indications Clinical Benefits • Staged/Fractionated Radiosurgery • Lesions adjacent to radiosensitive structures – 1-5 fractions/stages • Minimal or neurological deficit – Larger lesions • Complex-shaped lesions – Lesions next to critical structures/organs at risk • Previously irradiated lesions precluding further • Improved Patient Quality of Life external beam irradiation – Short treatment course: 1-5 days CyberKnife • Optimal for patients with limited life expectancy • Recurrent surgical lesions • Increased convenience • Lesions requiring difficult surgical approaches – No infection risk • Patients who are too frail for surgery or refuse – No general anesthesia surgery – Minimal to no recovery time • Short life expectancy Overview Lesion Type # Patients Spinal Radiosurgery (as of December 2004) Intracranial 7,192• Over 10,000 patients • Classically radio-resistant tumors: renal cell Spine 1,505 treated worldwide by CyberKnife Lung 466 and melanoma Nasopharynx 415• Over 100 peer-reviewed • In previously radiated fields to avoid clinical & technical Head/Neck/ENT 281 myelotoxicity papers published Pancreas 205• Types of lesions treated Liver 157 by CyberKnife Bone 79 Prostate 54 Others, i.e. kidney, 447 pelvis, etcCyberKnife® Radiosurgery System Other Clinical Applications • Broad clinical application • Primary & Recurrent H&N Cancers – Intracranial radiosurgery – Extracranial radiosurgery • Lung Tumors • Spine • Lung • Liver Tumors • Liver • Pancreas • Para-aortic & Intra-abdominal tumors • Prostate • Other • Pelvic tumors • Superior accuracy • Superior conformality • Proven clinical experience – Over 10,000 patients worldwide – Over 100 papers published 6
  • Fractionation Trilogy• Used when large tumor volumes are involved • Trilogy™ system can be used to• In intracranial 3-5 fractions employed for volumes deliver 3D conformal radiotherapy, of 40-50 ml. IMRT, stereotactic radiosurgery,• Fractionate to preserve important functions where fractionated stereotactic radiation the intergrity of involved critical structures is of therapy, and intensity-modulated paramount importance. Such as acoustic radiosurgery for cancer and neurmomas and visual acuityin cranial base meningiomas neurosurgical treatment. Trilogy (cont) Trilogy (cont)• 23EX Clinac® linear accelerator, which has been enhanced for stereotactic applications • First patient treated in October of 2004 that involve delivering higher doses of • Uses an On-Board Imager® to acquire radiation to smaller areas over a shorter period of time. images in real time• The Trilogy system is capable of delivering • Can treat both intra-cranial and extra cranial stereotactic radiosurgery by increasing its lesions maximum dose delivery rate from 600 to 1000 monitor units (MU) per minute and by fine- • Uses an array to treat extracranial lesions tuning the Clinac isocenter, or focal point, to a 1-millimeter diameter sphere Other SRS systems Synergy Trilogy® Stereotactic Beam on Linac • Elekta Synergy® S will integrate high resolution beam shaping, stereotactic target localization utilizing Elekta® XVI (X-ray Volume Imaging) technology, and organ motion control. Instead of the usual multi-leaf collimator (MLC), Elekta Synergy® S will feature Beam Modulator which allows much finer resolution Image not available beam shaping. • The combination of Elekta Synergy® with other purpose designed framing and fixation products will result in a clinically meaningful stereotactic solution for the localization and hypofractionated treatment of targets, both intra and extra-cranially. For single fraction intra-cranial treatment, the Gold Standard remains Leksell Gamma Knife®. 7
  • Nursing Implications Nursing Implications• Side effects, as with any type of radiation therapy, are limited to the area being treated • Pain management becomes important for• prudent that the nurse in the radiosurgery suite nurses in radiosurgery suite especially those review with the patient the side effects they may experience and pre-medicate the patient patients being treated for spinal lesions. appropriately with anti-emetics or pain medicine • Treatment can take any where from 30-2 as appropriate. hours and having a patient lie in position for• For example patients receiving CyberKnife® to the that long a period may cause significant lower thoracic and lumbar spine should receive pre-medication for nausea and education that pain and discomfort. nausea, vomiting, diarrhea or abdominal cramping are potential side effects to treatment of this area. 8