Partial boosting of prostate tumours

Background and purpose: In this planning study we propose a class solution for partial boosting of prostate tumours. Treatment margins and rectum dose are similar to that of the conventional treatment and are supposed to have no direct link to the level of dose escalation. We also study the robustne ss of our class solution in the presence of geometrical deviations. Methods and materials: To study the specifications of the class solution te n patients with histologically confirmed prostate cancer were replanned. Be sides a conventional plan for each patient, different partial boost plans w ere produced with an inverse treatment-planning tool. We also simulated tre atment geometrical deviations to estimate their effect on partial boost pla ns. Results: In our class solution we use three contours in our inverse treatme nt planning, which are based on the classical CTV. A three beam arrangement appeared to produce a dose distribution, which is comparable to that of a five or seven beam geometry. Comparison of partial boost plans and conventi onal plans indicated that all conditions for a partial boost plan could be satisfied with the proposed class solution. Simulation of treatment geometr ical deviations showed that large random deviations have a minor effect on the overall dose distributions, while systematic deviations may decrease th e boost dose and increase the rectal dose. Conclusions: We presented a class solution for partial boosting of prostate tumours in which the level of dose escalation is dealt with separately fro m the margin size and the nominal rectum dose. The framework put forward in this study allows practical introduction of intensity modulated radiothera py in routine clinical practice using current standards of imaging and posi tion verification. (C) 2001 Elsevier Science Ireland Ltd. All ri-hts reserv ed.