|
KMID : 0362919930110020421
|
|
Journal of the Korean Society for Therapeutic Radiology and Oncology
1993 Volume.11 No. 2 p.421 ~ p.430
|
|
|
Verification of Dose Distribution for Stereotactic Radiosurgery with a Linear Accelerator
|
|
Park Kyung-Ran
Kim Kye-Jun
Chu Sung-Sil
Lee Jong-Young
Joh Chul-Woo
Lee Chang-Geol
Suh Chang-Ok
Kim Gwi-Eon
|
|
|
Abstract
|
|
|
The calculation of dose distribution in multiple arc stereotactic radiotherapy is a three-dimensional problem and, therefore, the three-dimensional dose calculation algorithm is important and the algorithm´s accuracy and reliability should be confirmed experimentally. The aim of this study is to verify the dose distribution of stereotactic radiosurgery experimentally and to investigate the effect of the beam quality, the number of arcs of radiation, and the tertiary collimation on the resulting dose distribution.
Film dosimetry with phantom measurements was done to get the three-dimensional orthogonal isodose distribution. All experiments were carried out with a 6 MV X-ray, except for the study of the effects of beam energy on dose distribution, which was done for X-ray energies of 6 and 15 MV. The irradiation technique was from 4 to 11 arcs at intervals of from 15 to 45 degrees between each arc with various field sizes with additional circular collimator. The dose distributions of square field with linear accelerator collimator compared with the dose distributions obtained using circular field with tertiary collimator. The parameters used for comparing the results were the shape of the isodose curve, dose fall-offs from 90% to 50 % and from 90% to 20% isodose line for the steepest and shallowest profile, and A= (90% idsose area) /( 50% isodose area - 90% isodose area (modified from Chierego)). This ratio may be considered as being proportional to the sparing of normal tissue around the target volume.
The effect of beam energy in 6 and 15 MV X-ray indicated that the shapes of isodose cuties were the same. The value of ratio A and the steepest and shallowest dose fall-offs for 6 MV X-ray was minimally better than that for 15 MV X-ray. These data illustrated that an increase in the dimensions of the field from 10 to 28 mm in diameter did not significantly change the isodose distribution. There was no significant difference in dose gradient and the shape of isodose cutie regardless of the number of arcs for field sizes of 10, 21, and 32 ㎜ in diameter The shape of isodose cuties was more circular in circular field and square in square field. And the dose gradient for the circular field was slightly better than that for the square field.
|
|
|
KEYWORD
|
|
|
Stereotactic radiosurgery, Linear accelerator, Dose distribution, Film dosimetry
|
|
|
FullTexts / Linksout information
|
|
|
|
|
|
Listed journal information
|
|
|
|