For a number of years, one of us (J. A. C.) has been concerned about the relative value of irradiating the renal bed after in toto surgical removal of a malignant tumor such as Wilms'. This concern has also been stated by others (1). In an editorial, Raventos asks whether we should stop treating children with x-rays (2). In view of this, as well as the extreme interest and wide publicity regarding radiation hazards, an attempt was made to measure gonadal doses, in phantoms, for simulated radiation procedures in infants and children. Methods Phantoms of children aged six months, six years, and twelve years were constructed of papier-mâche. The paper forms were several layers thick and approximated the skin. They were then filled with rice which was packed quite firmly. Sponge rubber was used for the lungs, with tightly filled rice bags as the mediastinal structures. A 250-kv General Electric Maximar therapy unit was used for deep therapy, with filtration of 1 mm. Al and 0.5 mm. Cu, h.v.l. of 1.4 mm. Cu, an...