Correlation of clinical target volume and the margins to define planning target volume with beam arrangements for three-dimensional conformal radiation therapy delivery for prostate cancer

english

2005

volume 39, issue 4

prostate   Prostatic Neoplasms   Radiotherapy   Radiotherapy Dosage   tumor

Društvo radiologije in onkologije
(Obvezni izvod spletne publikacije)

Background. A conceptual study was undertaken to correlate the clinical targetvolume and the margins to define the planning target volume with the beam arrangements for a three-dimensional conformal radiation therapy deliveryon two patients with prostate cancer having considerably different prostate shapes and volumes. Material and methods. The clinical target volume was defined as prostate and seminal vesicles. Uniform margins of 0.4, 0.8 and 1.2 cm were added around the clinical target volume to define three planning target volumes. Three well-established coplanar beam arrangements were simulated for all planning target volumes. Dose-volume histograms were calculated and quantitatively compared. Results. The mean dose (Dm) for PTVs ranged from 98.7 to 99.9%, with standard deviations ranging from 1.5 to 1.7%. Plan I appeared to be the best considering the Dm for the rectum, whereas PlanII appeared to be the best considering V95 (fraction of volume receiving adose higher than 95% of the isocenter dose for the rectum). Plan III appearedto be the best considering the Dm and V95 for the bladder and also considering the Dm and V50 for the femur. Conclusions. This conceptual study suggested that the differences in shapes and volumes of planning target volumemight be taken into consideration in an attempt to individually establish the optimum beam arrangements for three-dimensional conformal radiation therapy delivery in prostate cancer.

16.09.2009