A gamma sugársebészet pathológiai alapjairól PDF Nyomtatás E-mail
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2009. július 03. péntek, 10:46

A PATHOLÓGIA SZEREPE A SUGÁR AGYSEBÉSZET FEJLÖDÉSÉBEN

Dr. med.habil. Szeifert György
Országos Idegsebészeti Tudományos Intézet
Semmelweis Egyetem Idegsebészeti Tanszék

 

 

Stereotaxiás sugársebészet

  • Célja: "a kóros, vagy normális sejteket tartalmazó meghatározott céltérfogat teljes és pontos megsemmisítése egyszeri, nagy dózisú sugárkezeléssel, a környezö szövetek károsítása nélkül."

Professor Lars Leksell (1907-1986)

 

Linearis accelerator (LINAC): mozgó sugárforrás és célpont

 

Gamma Kés: fixált sugárforrások + fixált célpont

 

Gamma Kés: Stockholm, 1968

 

CNS PROJECT for Radiosurgical Pathology

 

 

WHAT CAN WE LEARN FROM PATHOLOGY?

 

Leonardo da Vinci (1452-1519): first anatomical image collection

 

Andreas Vesalius (Brussels:1514-Jerusalem?:1564)

  • First systematic anatomical lessons
  • "De humani et corporis fabrica": 1543
  • Totally based on human experience
  • Teachings of Galenos was developed

 

Giovanni Battista Morgagni (1682-1771)

  • Systematic human pathological-anatomy lessons
  • "De sedibus et causis morborum�": 1761
  • Founder of clinical pathology

 

Japanese anatomical studies

 

The basic histopathological lesion in radiosurgery

  • Larsson, Leksell et al.: The High-energy Proton Beam as a Neurosurgical Tool. Nature 182; 1222-1223, 1958.
  • In animal experiments "�with high-energy protons a sharply delimited lesion can be made at any desired site in the central nervous system."

 

The pathological effect of radiosurgery on the CNS tissue

  • Degenerative changes (coagulation necrosis, endothelial destruction, apoptosis, hyaline degeneration)
  • Proliferative changes (granulation tissue formation, proliferation of fibrocytes, fibroblasts, myofibroblasts, capillaries, inflammatory cells, collagen production)

 

Coagulation necrosis created by high energy irradiation

  • Is within the target volume
  • the boundary of the lesion is distinct according to the sharp radiation fall- off
  • does not change in time

 

Radiosurgical pathology of vascular malformations

  • Arteriovenous malformations
  • Cavernomas
  • (Capillary teleangiectasias,
  • DVA: No surgery, no RS)

 

Incompletely obliterated AVMs

 

Angiographically complete AVM obliteration

 

Increased metabolic activity at the region of the AVM 7 years after RS

  • "�increased enhancement of the nidus after contrast or gadolinium administration could persist even after obliteration of the AVM was angiographically confirmed�
  • ...as long as 8 years after radiosurgery,"

 

Message of pathology

  • Until thrombus organization has not been completed in the AVM vessels after radiosurgery, neovascularization may supply a potential source for re-bleeding.
  • The role of PET examination should be considered to asses metabolic activity of AVMs after radiosurgery.

 

Cavernomas

 

40 Gy irradiated cavernoma (fractionated)

 

The message of pathology

  • The irradiation evokes endothelial damage,
  • granulation tissue and
  • scar tissue production in cavernomas as well

 

Radiosurgical pathology for tumors

  • Cerebral metastases
  • Vestibular schwannomas
  • Gliomas

 

Message of pathology

  • Patchy, inhomogeneous contrast enhancement on CT and MR images reflects necrotic tumor areas, i.e. hypoxic neoplastic tissue.
  • Lesions demonstrating a similar radiological pattern require higher doses (18Gy minimum or more) to obtain control.

 

Vestibular schwannoma

 

Message of pathology

  • Supports the hypothesis that vascular endothelial cells are the principal targets of single high-dose irradiation.
  • The loss of central contrast enhancement of tumor tissue following radiosurgery might be consequence of the vascular damage.

 

Malignant astrocytic tumor (C-11 Methionine PET)

 

Message of pathology

  • Morphological re-differentiation can occur in malignant astrocytic tumor after radiosurgery.
  • Radiosurgery may promote some degree of restoration of the p53 gene tumor suppressor function.

 

Experimental radiosurgical pathology

  • Animal experiments
  • Tissue culture studies

 

What can we learn from pathology?

  • "The future of radiosurgery will be built on three foundations.
  • First, a better understanding of the biologic effects of radiation will enable treatment of new disorders.
  • Second, technologic advancements�
  • Third, new clinical applications will derive from radiobiological knowledge�"

 

Radiosurgical pathology

  • Is it a new subspeciality?
  • Do we need it?
  • Quo vadis?

 

"Mortui vivos docent"

 
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