|
KMID : 0362919890070010101
|
|
Journal of the Korean Society for Therapeutic Radiology and Oncology
1989 Volume.7 No. 1 p.101 ~ p.112
|
|
|
Treatment Planning and Dosimetry of Small Radiation Fields for Stereotactic Radiosurgery
|
|
Chu Sung-Sil
Suh Chang-Ok
Loh John-JK
Chung Sang-Sup
|
|
|
Abstract
|
|
|
The treatment planning and dosimetry of small fields for stereotactic radiosurgery with 10 MV x-ray isocentrically mounted linear accelerator is presented. Special consideration in this study was given to the variation of absorbed dose with field size, the central axis percent depth doses and the combined moving beam dose distributon. The collimator scatter correction factors of small fields (1×l∼3×3 ㎠) were measured with ion chamber at a target chamber distance of 300㎝ where the projected fields were larger than the polystyrene buildup caps and it was calibrated with the tissue equivalent solid state detectors of small size (TLD, PLD, ESR and semiconductors).
The central axis percent depth doses for 1×1 and 3×3 ㎠ fields could be derived with the same acuracy by interpolating between measured values for larger fields and calcu1ated zero area data, and it was also calibrated with semiconductor detectors. The agreement between experimental and calculated data was found to be under ±2% within the fields. The three dimensional dose planning of stereotactic focusing irradiation on small size tumor regions was performed with dose planning computer system (Therac 2300) and was verified with film dosimetry. The more the number of strips and the wider the angle of arc rotation, the larger were the dose delivered on tumor and the less the dose to surrounding the normal tissues.
The circular cone, we designed, improves the alignment, minimizes the penumbra of the beam and formats ball shape of treatment area without stellate patterns. These dosimetric techniques can provide adequate physics background for stereotactic radiosurgery with small radiation fields and 10 MV x-ray beam.
|
|
|
KEYWORD
|
|
|
Small field, Circular cone, Stereotactic radiosurgery, Scatter correction factors, Tissue maximum ratio, Percent depth dose
|
|
|
FullTexts / Linksout information
|
|
|
|
|
|
Listed journal information
|
|
|
|