Abstract
The accurate positioning of treatment fields has always been difficult, and becomes even more important when two fields are adjacent and a gap must be calculated. The standard formula (based on similar triangles) assumes a flat surface. In Hodgkin's patients the gapping between the mantle and para-aortic fields involve sloping surfaces and the patient thickness can vary as much as 5 or 6 cm between central axis and the lower edge of the mantle field. Due to the divergence of a large mantle field, using the standard formula and gapping on the skin surface can lead to an overlap of 7 to 9 mm and a region which can receive 140% of the midplane dose. A modification of the existing formula which takes into account sloping surfaces has been formulated for both source-skin-distance and isocentric treatments. In addition, problems in positioning related to mantle fields when treating the patient prone and supine have been investigated.
| Original language | English |
|---|---|
| Pages (from-to) | 1183-1190 |
| Number of pages | 8 |
| Journal | International journal of radiation oncology, biology, physics |
| Volume | 18 |
| Issue number | 5 |
| DOIs | |
| State | Published - May 1990 |
Keywords
- Gapping fields
- Hodgkin's disease
- Mantle field