Ultrasound localization of the ovaries for radiation-induced ovarian ablation

The case notes and simulator films were reviewed from 70 sequential patient s who received pelvic irradiation to induce an early menopause as part of t heir treatment for breast cancer at the Staffordshire Oncology Centre. Thes e patients underwent ultrasound localization of the ovaries immediately pri or to simulation. Altogether, 128 ovaries were plotted on a diagrammatic re presentation of a gynaecoid pelvis to represent their position in both cran iocaudal and lateral dimensions in relation to the true bony pelvis. The craniocaudal ovarian position varied from 2.5 cm above the lower aspect of the sacroiliac joint to 2.0 cm above the symphysis pubis. Three (4.6%) right sided ovaries were within 1 cm medial to the right lateral side wall, with none lying lateral to the wall. Seventeen (26%) left sided ovaries we re lying within 1 cm of the left pelvic side wall, with four of these lying outside. The limits of the pelvic fields used were from the top of the sacroiliac jo int to the bottom of the symphysis pubis. Sixty-one (88%) upper borders wer e on or above the lower sacroiliac joint. Twenty six (38%) and 49 (71%) fie lds were outside the right and left pelvic side walls respectively. This wo uld suggest that field sizes were larger than standard; however, 87% were s maller than 150 cm(2) (assuming a 10 x 15 cm field as standard). Only one p atient failed to respond to treatment. This was thought to be due to underd osing rather than a geographical miss. This patient was successfully retrea ted. The authors advocate the use of ultrasound localization prior to planning a n irradiation menopause, to ensure that the ovaries are encompassed in the pelvic field, thus preventing a geographical miss and reducing field sizes.