Permanent planar iodine-125 implants: the dosimetric effect of geometric parameters for idealized source configurations.
OBJECTIVE
To provide dosimetric information about permanent planar (125)I implants in a manner that is useful to the brachytherapist in the operative setting.


METHODS
Reference planar permanent implants were simulated for a variety of areas with sources placed uniformly on a 1-cm grid. Implants having variable source spacing and curvature were simulated and compared with the reference implants. Dosimetric measures were calculated at 0.5 and 1.0 cm from the implant plane.


RESULTS
A method for calculating dosimetric statistics for permanent implants ranging from 5 x 5 cm to 13 x 13 cm is presented. A formula to predict the reference source strength needed to achieve a desired dosimetric quantity is also presented. The effect of adjusting strand spacing to compensate for source activity is presented and is shown to be an effective means to adjust implants to use source strengths other than the reference strength. The effect of implant curvature compared with flat implants on dosimetric statistics is presented as a function of radius of curvature.


CONCLUSIONS
The results presented in this work may be used to provide information about dose delivered from planar permanent implants.
Cormack
Robert A
RA
Division of Brachytherapy, Department of Radiation Oncology, Dana Farber/Brigham and Women's Cancer Center, Boston, MA 02215, USA. rcormack@lroc.harvard.edu
Holloway
Caroline L
CL
O'Farrell
Desmond
D
Devlin
Phillip M
PM
D000465:Algorithms; D001918:Brachytherapy / Q000295:instrumentation / Q000379:methods*; D006801:Humans; D007457:Iodine Radioisotopes / Q000627:therapeutic use*; D011874:Radiometry / Q000379:methods; D011879:Radiotherapy Dosage; D011880:Radiotherapy Planning, Computer-Assisted; D013679:Technology, Radiologic / Q000379:methods
D007457:Iodine Radioisotopes