Surface dose reduction achieved by means of a lead glass filter in case of teletherapy with Co 60 radiation
Description
The surface dose of irradiated patients can be reduced by the insertion of a lead glass filter with a thickness of 4 mm at the ray emergence point of a Co 60 gammatron. The lead glass which is made stable against color alterations by radiation, will absorb the secondary electrons produced by the gamma radiation at the collimator and shutter system of the gammatron. The filter allows to reduce the surface dose in a tissue depth of 0,05 to 0,1 mm by a maximum rate of 16% according to the size of the irradiation field. Measurements were taken with a soft radiation chamber in serveral tissue depths within and outside the field using three different filtering methods (without any filter, 1 mm plexiglas, 4 mm lead glass). There are essential advantages for teletherapy of deep tumors by the use of a lead glass filter, so that the insertion of such a filter is recommended for all Co 60 units. (orig.)
Abstract (German)
Durch Einsatz eines 4 mm starken Bleiglasfilters am Strahlenaustritt eines Co-60-Gammatrons kann die Hautdosis bei Bestrahlung von Patienten reduziert werden. Das gegen Strahlenverfaerbung stabilisierte Bleiglas absorbiert die Sekundaerelektronen, die durch die Gammastrahlen am Kollimator- und Blendensystem des Gammatrons erzeugt werden. Je nach Groesse des Bestrahlungsfeldes kann in einer Gewebetiefe von 0,05 bis 0,1 mm die Oberflaechendosis mit dem Filter um maximal 16% erniedrigt werden. Es wurden Messungen mit einer Weichstrahlkammer in verschiedenen Gewebetiefen innerhalb und ausserhalb des Feldes fuer drei Filterungen (ohne Filter, 1 mm Plexiglas, 4 mm Bleiglas) vorgenommen und miteinander verglichen. Bei der Teletherapie tiefliegender Tumoren bietet der Einsatz eines Bleiglasfilters wesentliche Vorteile, so dass die Ausruestung aller Co-60-Anlagen mit einem derartigen Filter empfohlen wird. (orig.)Additional details
Additional titles
- Original title (German)
- Hautdosisreduktion bei der Teletherapie mit Co-60-Strahlen durch Einsatz eines Bleiglasfilters
Publishing Information
- Journal Title
- Strahlentherapie
- Journal Volume
- 157
- Journal Issue
- 10
- Series
- Strahlentherapie.
- Journal Page Range
- 662-666
- ISSN
- 0039-2073
INIS
- Country of Publication
- Germany
- Country of Input or Organization
- Germany
- INIS RN
- 13669170
- Subject category
- S62: RADIOLOGY AND NUCLEAR MEDICINE; S61: RADIATION PROTECTION AND DOSIMETRY; S61: RADIATION PROTECTION AND DOSIMETRY;
- Descriptors DEI
- COLLIMATORS; COMPTON EFFECT; ELECTRON LOSS; FILTERS; FOCUSING; GAMMA SOURCES; GLASS; IONIZATION CHAMBERS; KEV RANGE 100-1000; LEAD; PHANTOMS; PLEXIGLAS; RADIATION DOSE DISTRIBUTIONS; RADIATION PROTECTION; RADIOTHERAPY; SKIN; SURFACE CONTAMINATION; TISSUE-EQUIVALENT MATERIALS
- Descriptors DEC
- BASIC INTERACTIONS; BODY; CONTAMINATION; ELASTIC SCATTERING; ELECTROMAGNETIC INTERACTIONS; ELEMENTS; ENERGY RANGE; ESTERS; INTERACTIONS; KEV RANGE; MEASURING INSTRUMENTS; MEDICINE; METALS; MOCKUP; ORGANIC COMPOUNDS; ORGANIC POLYMERS; ORGANS; POLYACRYLATES; POLYMERS; POLYVINYLS; RADIATION DETECTORS; RADIATION SOURCES; SCATTERING; STRUCTURAL MODELS; THERAPY