Igrt for cervical cancer feb 8 2013 920 a cancer ci 2013
01 suh brain anatomy, planning and delivery hyderabad 2013 (cancer ci 2013) john h. suh
1. Basics of Anatomy, Planning and Treatment
Delivery for Brain Tumors
John H. Suh, M.D.
Professor and Chairman, Dept. of Radiation Oncology
Associate Director of the Gamma Knife Center
Rose Ella Burkhardt Brain Tumor and Neuro-oncology Center
Taussig Cancer Institute
3. Objectives
• Provide overview of brain anatomy
• Review advances in treatment planning and delivery
oncology that have allowed optimization of radiation
therapy of brain tumors.
• Discuss methods to direct dose to the tumor while
minimizing dose to the normal neural tissues.
• Review advances in stereotactic radiosurgery.
11. RTOG Atlas
Red: Hippocampus Green: Hippocampal Avoidance Zone
Hippocampal
1)Hippocampal
Tail
1) Tail
2) Body
3)2) Body
Head
3) Head
The hippocampus has three anatomic subdivisions: the head, body, and tail; note that the head
is inferior or caudad, the body is superoposterior and the tail is most cephalad (superior) and
posterior, and an overall “banana” shape emerges on sagittal images, located in the plane of the
lateral ventricle.
MR Images courtesy of: Holmes CJ, Hoge R, Collins L, et al. "Enhancement of MR Images Using Registration for Signal
Averaging" Journal of Computer Assisted Tomography 22, 324-333 (1998)
15. Conventional Radiotherapy
Conventional
Beam Shaper
Desired Actual
Dose Dose
Distribution Distribution
16. CT simulator use in radiation oncology
Provides cross sectional anatomical information
1) Target volume delineation
2) Relative geometry of critical structures
3) Beam placement and field shaping
4) Dose distribution calculation and analysis
39. RTOG 0933
Phase II Trial of Hippocampal Avoidance During Whole
Brain Radiotherapy for brain metastases
• Fused planning MRI CT
image set
• Hippocampal avoidance
regions will 3D expansion of
hippocampal contours by 5
mm.
41. Importance of optimizing image performance to
achieve fundamental objectives of radiation therapy
Dawson LA et al. The Oncologist 15:338-349, 2010
42. Stereotactic Radiosurgery
“Replace the needle by narrow
beams of radiation energy and
thereby produce a local
destruction of the tissue”
Lars Leksell
The stereotaxic method and
radiosurgery of the brain
Acta Chirurgica Scandinavia Vol 102,
Fasc 4, 1952
60. Different linac approaches for brain SRS
Dynamic Conformal Arc
Conformal Beam
Circular Arc
IMRT
HybridArc
61. Frameless Cranial Stereotaxy
• Upper palate based immobilization
– Good dentition helpful
– Must be able to tolerate the mouthpiece
• Mask based
– More uncertainty
• Relocatable
– Hypofractionation
– Larger lesions
– Near dose sensitive structures
– Post op cavity
– Prior RT
– Image guided
– Skull is an excellent fiducial marker
– Reusable
• Not restricted by physical limitations
62.
63. Radiation oncology team
• Therapists
• Nurses and nurse practitioners
• Dosimetrists
• Medical physicists
• Clinical engineers
• Schedulers
• Secretaries
• Radiation oncologists
Strong teamwork and q/a program helps ensure proper and
safe radiation delivery
64. Conclusions
• Understanding brain anatomy and dose
constraints are essential.
• Technical advances in radiation oncology have
allowed optimization of radiation delivery for brain
tumors.
• Dose painting, dose sculpting, and conformal
avoidance for brain tumors can be achieved given
the advances in technology, imaging and
treatment planning.
65. Title of Presentation Arial Regular 22pt
Single line spacing
Up to 3 lines long
Date 20pts
Author Name 20pts
Author Title 20pts
Notas do Editor
The goal of radiation therapy is to maximize tumor control while minimizing complications. This axes of this graph represent Dose on the X-axis and tumor control or complications to normal tissues on the Y-axis. With respect to tumor control, as dose increases, the chance of tumor control increases. Likewise as dose increases, so does the probability of complication (represented by the red curve). Both these curves are sigmoidal in shape. Initially with low doses, there is little cell kill, and hence little tumor control. At a certain dose, the probability of cell kill increases dramatically, and hence high tumor control. However, beyond a certain dose, the curve again flattens so that increases in dose (while still toxic to tumor), does not increase the probability of further cell killing beyond what a lower dose can achieve. The risk of complication follows this same paradigm. Low dose has little chance of causing complication. However, at certain doses, the complication rate climbs sharply. These curves tend to be parallel, and the goal of radiation oncology is to maximize the potential for tumor killing (or tumor control) while minimizing the potential for normal tissue complications. The white vertical dashed line represents this compromise in therapeutic efficacy to achieve maximal tumor control with minimal normal tissue complication.
Diagram depicting the importance of optimizing imaging performance based on the fundamental objectives of radiotherapy (outer circle). Trade-offs among geometric integrity, tissue contrast, and spatial resolution must be considered when designing time-efficient image acquisition protocols.
The goal of radiation therapy is to maximize tumor control while minimizing complications. This axes of this graph represent Dose on the X-axis and tumor control or complications to normal tissues on the Y-axis. With respect to tumor control, as dose increases, the chance of tumor control increases. Likewise as dose increases, so does the probability of complication (represented by the red curve). Both these curves are sigmoidal in shape. Initially with low doses, there is little cell kill, and hence little tumor control. At a certain dose, the probability of cell kill increases dramatically, and hence high tumor control. However, beyond a certain dose, the curve again flattens so that increases in dose (while still toxic to tumor), does not increase the probability of further cell killing beyond what a lower dose can achieve. The risk of complication follows this same paradigm. Low dose has little chance of causing complication. However, at certain doses, the complication rate climbs sharply. These curves tend to be parallel, and the goal of radiation oncology is to maximize the potential for tumor killing (or tumor control) while minimizing the potential for normal tissue complications. The white vertical dashed line represents this compromise in therapeutic efficacy to achieve maximal tumor control with minimal normal tissue complication.
Due to its complete integration Novalis is the only SRS/SRT machine in the market that can safely deliver Dynamic Shaped Beam Surgery (dynamic arc). Please save the AVI file “mlc 400x300 Cinepak 12fps 300kbs.avi” in the same folder as this powerpoint for animation.
iPlan RT Dose offers a wide range of tools for treating various indications. Circular arc treatments utilize conical collimators to deliver a spherical dose with a sharp dose fall off, ideal for small spherical mets or functional indications such as trigeminal neuralgia. Conformal beam treatments consist of multiple static beams each with a fixed MLC position based on the shape of the target, ideal for wedged tumors where arcs would hit too many critical structures or for some extracranial targets. Dynamic conformal arcs provide a treatment in which the gantry rotates about the patient and as the gantry rotates, the MLC shapes to the target dynamically. Dynamic arc treatments are used in most cranial treatments with the benefit of normal tissue sparing and increased conformity to the target. IMRT treatments have static beams with dynamically moving MLCs which are used to selectively block dose or deliver dose in particular areas based on the prescription constraints. IMRT is used when you are concerned with sparing adjacent critical structures such as the spinal cord. Finally, our newest delivery technique is HybridArc. HybridArc is an automated blending of enhanced Dynamic Conformal Arcs (modulated arcs) and static IMRT fields.