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Spencer-Attix Cavity Theory
Linköping University, Department of Medicine and Care, Radio Physics. Linköping University, Faculty of Health Sciences. Östergötlands Läns Landsting, Centre of Surgery and Oncology, Department of Radiation Physics.ORCID iD: 0000-0003-0209-498X
2002 (English)Report (Other academic)
Abstract [en]

The cavity theory by Spencer and Attix treats the energy deposition in a Bragg-Gray (B-G) cavity (detector). Originally the theory was developed for the case of a B-G detector inside a medium irradiated with photons and assuming electronic equilibrium in the medium at the position of the cavity. The theory is also applicable in media irradiated with other types of uncharged ionizing particles (e.g., neutrons) and charged particles such as electrons and protons.

The special case of photon irradiation under CPE (charged particle equilibrium) conditions was coupled to a model for calculating the energy spectrum of the equilibrium fluence of electrons in the undisturbed medium. For other situations, e.g., in a medium externally irradiated with electrons, the problem is to evaluate the energy spectrum of the electron fluence at the point considered in the medium. Today, this is mostly accomplished using Monte Carlo simulations.

A Bragg-Gray cavity is regarded to be so small that:

  • the energy imparted to the cavity from electrons released by photons in the cavity is negligible compared to the energy imparted from electrons released by photons in the surrounding medium and passing through the cavity
  • the cavity should not disturb the fluence of electrons in the medium, i. e., the fluence of electrons traversing the cavity is assumed to be identical to that existing at the point of interest in the medium in the absence of the cavity.
Place, publisher, year, edition, pages
Linköping: Linköping University Electronic Press , 2002. , 17 p.
Report / Department of Radiology, Linköping University, 1998-, -
National Category
Radiology, Nuclear Medicine and Medical Imaging
URN: urn:nbn:se:liu:diva-57893OAI: diva2:328337
Available from: 2010-07-02 Created: 2010-07-02 Last updated: 2015-03-20Bibliographically approved

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Alm Carlsson, Gudrun
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Radio PhysicsFaculty of Health SciencesDepartment of Radiation Physics
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