A dosimetric analysis of interstitial intensity modulated implants for pelvic recurrences, base of tongue and orbita tumors with specific references to the ICRU-58.
OBJECTIVE
In this article the conversion of the dosimetry of three different kinds of IMBT (intensity modulated brachytherapy) implants into ICRU-58 formalism is presented. The results allow an inter-study comparison of relative reference doses between different sites.


METHODS
The evaluation included 76 patient plans: (a) 31 pelvic recurrences, (b) 30 base of tongue tumors, and (c) 15 orbita tumors were analysed retrospectively and the mean central doses (MCD) and relative reference doses were evaluated.


RESULTS
The reference doses D(ref) normalized to the mean central doses of three subgroups resulted in (a) 66%, (b) 68%, and (c) 52%. This is in contrast to the generally proposed standard reference dose of 85% of the Paris system.


CONCLUSIONS
Reduction of the reference dose yields to higher dose inhomogeneities and affects the positive local tumor control. It was found that in IMBT implants the 85% reference dose of the Paris system is suitable for reporting purposes but not necessarily for dose prescription. Consequently, in IMBT implants the prescription dose of 85% should be critically used.
Siebert
Frank-Andre
FA
Clinic of Radiotherapy, University Hospital of Schleswig-Holstein, Kiel, Germany. siebert@onco.uni-kiel.de
Born
Thilo
T
Häring
Stefanie
S
Seefeld
Frank
F
Kovács
György
G
D000293:Adolescent; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D001918:Brachytherapy / Q000295:instrumentation* / Q000379:methods / Q000592:standards*; D002648:Child; D002675:Child, Preschool; D015179:Colorectal Neoplasms / Q000532:radiotherapy*; D004307:Dose-Response Relationship, Radiation; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D009918:Orbital Neoplasms / Q000532:radiotherapy*; D010386:Pelvic Neoplasms / Q000532:radiotherapy* / Q000556:secondary; D011829:Radiation Dosage; D012015:Reference Standards; D012189:Retrospective Studies; D014062:Tongue Neoplasms / Q000532:radiotherapy*