Potentials of computed tomography in radiation therapy treatment planning.

CT can provide detailed 3-dimensional representation of diseased and dose-limiting structures; it detects lung metastases and may be of use in follow-up studies. The potential use of the electron density cross section may be limited by (a) the small number of planning situations where inhomogeneity corrections are truly useful, (b) the lack of sensitivity of certain correction schemes (e.g., megavoltage photons), (c) the inherent inaccuracy of certain correction schemes, (d) the inaccuracy of in vivo determinations of electron density and (e) the narrow range of electron densities observed in most soft tissues of the body.