The application of dose-volume histograms to the Paris and Manchester systems of brachytherapy dosimetry.
When the geometry of an implant does not exactly follow a system of dosimetry problems arise in choosing a treatment dose rate. This study has investigated the use of natural dose-volume histograms (DVHs) as a means for choosing the treatment dose level in these cases. A number of ideal geometrical cases have been investigated. For these, where appropriate, the Paris or Manchester dose rates have been calculated and compared with the peak position of the natural DVH. The dose rate at the peak of the DVH was found to agree with the basal dose rate calculated according to the Paris rules. For implants that completely obeyed the Paris rules the mean ratio was 1.009 +/- 4%. A series of clinical implants was also examined. For these the mean ratio was 1.002 +/- 2.5%. It is concluded that the peak position of a DVH can be used to predict the Paris basal dose rate of an implant. There was no systematic relationship found between the Manchester dose rate and the peak position of the DVH. The mean ratio between the Manchester dose rate and the peak dose rate position of the DVH was 0.82 +/- 13% for a series of implants.
Langmack
K A
KA
Medical Physics Department, Addenbrooke's Hospital, Cambridge, UK.
Thomas
S J
SJ
D001918:Brachytherapy; D006801:Humans; D011874:Radiometry / Q000379:methods; D011879:Radiotherapy Dosage; D011880:Radiotherapy Planning, Computer-Assisted / Q000379:methods*