Quality assurance in stereotactic radiosurgery/radiotherapy according to DIN 6875-1

The new DIN (' Deutsche Industrie- Norm') 6875- 1, which is
currently being finalised, deals with quality assurance ( QA)
criteria and tests methods for linear accelerator and Gamma Knife
stereotactic radiosurgery/ radiotherapy including treatment
planning, stereotactic frame and stereotactic imaging and a system
test to check the whole chain of uncertainties. Our existing QA
program, based on dedicated phantoms and test procedures, has been
refined to fulfill the demands of this new DIN. The radiological
and mechanical isocentre corresponded within 0.2 mm and the
measured 50% isodose lines were in agreement with the calculated
ones within less than 0.5 mm. The measured absorbed dose was within
3%. The resultant output factors measured for the 14-, 8- and 4- mm
collimator helmet were 0.9870 +/- 0.0086, 0.9578 +/- 0.0057 and
0.8741 +/- 0.0202, respectively. For 170 consecutive tests, the
mean geometrical accuracy was 0.48 +/- 0.23 mm. Besides QA phantoms
and analysis software developed in- house, the use of commercially
available tools facilitated the QA according to the DIN 6875- 1
with which our results complied. Copyright (C) 2004 S. Karger AG,
Basel.