EDITOR—Kunkler's editorial on adjuvant irradiation for breast cancer addressed an important problem.1 More and more patients of all age groups with potentially highly curable disease are being treated with both adjuvant chemotherapy and radiation. It is therefore most important that the treatment should be given in the safest possible manner while maintaining its therapeutic advantage. Increasingly, people recognise that radiotherapy can improve survival in breast cancer, and practitioners are becoming aware not just of the cardiac morbidity that occurs but also of the cardiac mortality.

To investigate the magnitude of these problems we have undertaken a series of magnetic resonance scans on patients before radiotherapy planning and treatment. The advent of magnetic resonance imaging has allowed us to quantify the accuracy with which radiotherapy treatments are being delivered in breast cancer. The architecture of our magnetic resonance scanner is open and allows patients to be scanned in the treatment position. Magnetic resonance images have the advantage over other imaging techniques in that they …