[Volumetric changes of the breast during radiotherapy. Is a replanning necessary for the electron boost?]. / Volumetrische Veränderungen der Mamma während der Radiotherapie. Ist vor Boostbestrahlung mit Elektronen eine Nachplanung erforderlich?

BACKGROUND AND PURPOSE: Radiotherapy can induce tissue reactions with an edema leading to increased breast volume. The aim of the present study was to quantify this increase and analyze its effect on the electron boost technique. PATIENTS AND METHODS: 140 patients with breast cancer treated with breast-conserving surgery underwent CT planning before, during and/or after radiotherapy in order to evaluate breast volume changes due to radiotherapy. CT data were analyzed using the HELAX planning system and dose distribution was assessed. Determination of the breast volume was achieved using an interpolation algorithm. Three subgroups were analyzed: group 1 (n = 47): < or = 670 cm(3), group 2 (n = 46): 671-999 cm(3), and group 3 (n = 47): > or = 1000 cm(3) breast volume. RESULTS: The mean initial breast volume was 907 cm(3) (100-3073 cm(3)). After radiotherapy, mean breast volume increased by 81 cm(3) to 988 cm(3) (109-3185 cm(3)). Significant changes in volume were observed after a dose of 40 Gy. According to the subgroups mean volume increase was as follows: group 1: 53 cm(3) (3-120 cm(3)), group 2: 85 cm(3) (20-200 cm(3)), and group 3: 105 cm(3) (5-340 cm(3)). This difference was statistically significant for all subgroups (p < 0.001). Corresponding to the volume increase, depth of the boost target volume changed up to 1.0 cm. CONCLUSION: As radiotherapy may lead to a significant increase in breast volume, it seems appropriate to perform a second planning CT after about 40 Gy in order to optimize dose distribution for boost irradiation.

[Craniospinal irradiation -- patient positioning and verification with portal films]. / Kraniospinale Bestrahlung -- Patientenlagerung und Verifikation.

BACKGROUND: Implementation of an important step for quality assurance in irradiation of the craniospinal axis was made through changes in the irradiation technique. Crucial improvements in patient positioning and the possibility of taking portal films of the field junctions are described. MATERIAL AND METHODS: A box for the positioning of the head of the patient in has been developed. In combination with vacuum cushions, it is a cheap method for the individual and secure positioning of the patient in prone position. Furthermore, a method for taking portal films of the field junctions between the lateral cranial and the upper dorsal spinal field as well as between the two dorsal spinal fields is described. DISCUSSION: The use of the "Bonner Box" improves the patient positioning with respect to reproducibility, setup time and comfort. The documentation of the field junctions in craniospinal irradiation, which is described for the first time, is an important tool for quality assurance.