Definition and validation of a reference target volume in early stage node-positive cervical carcinoma, based on lymphangiograms and CT-scans

Purpose: To establish a reference planning target Volume for postoperative radiotherapy in stage Ib and IIa N + cervical carcinoma, based on 47 lympha ngiograms and 15 CT-scans. Methods: Radiation oncologists (n = 17) from all radiotherapy institutes in The Netherlands were asked to define the clinical target volume (CTV) and planning target volume (PTV), and to delineate (on simulation films) the ra diotherapy treatment portals following a radical hysterectomy with lymph no de dissection for an early stage cervical carcinoma with positive iliac lym ph nodes. A reference PTV was defined by using 47 normal lymphangiograms an d CT-data of the pelvis from 15 patients who underwent surgery for cervical carcinoma. The simulation films were digitized and evaluated for adequacy in covering the PTV, previously individually determined by che radiation on cologists. Subsequently, the simulation films were also evaluated for adequ acy in covering the reference PTV. Results: Large Variations were observed in the portals used and in treatmen t techniques. From the digitized films, it appeared that in 50% of the case s the defined PTV was not covered adequately. Furthermore, 71% of the treat ment plans would not cover the lateral borders of the reference PTV suffici ently. Conclusions: There appears to be no consensus on the target volumes to be i rradiated in postoperative radiotherapy of early stage cervical carcinoma. When a PTV defined on the basis of lymphangiograms and CT-data is taken as a reference, 71% of the treatment plans would not cover this PTV adequately . These findings indicate the need for a consensus in the design of standar dized treatment volumes. Published by Elsevier Science Ireland Ltd.