An analysis of an implantable dosimeter system for external beam therapy.
OBJECTIVE
To review the data from an implantable radiation dosimetry system used in a clinical setting and to examine correlations between dosimeter readings and potential causative error sources.


METHODS
MOSFET (metal oxide semiconductor field effect transistor) based encapsulated dosimeters were evaluated in a phantom (in vitro) and in a study with 18 patients. The dosimeters were placed in the gross tumor volume or in collateral normal tissue. Predicted dose values were established by imaging the dosimeters in the planning CTs.


RESULTS
The in vitro study confirmed that bounding cumulative errors due to setup, planning, and machine output within a +/-5% level is achievable. In patients, it was found that deviations from the targeted dose often exceeded the 5% level.


CONCLUSIONS
The use of an implantable dosimeter system could provide an effective empiric check on the dose delivered at depth. Such a tool may have value for institutional quality assurance, as well as for therapy delivered to individual patients.
Black
Robert D
RD
Sicel Technologies, Morrisville, NC 27560, USA. bblack@siceltech.com
Scarantino
Charles W
CW
Mann
Gregory G
GG
Anscher
Mitchell S
MS
Ornitz
Robert D
RD
Nelms
Benjamin E
BE
D004307:Dose-Response Relationship, Radiation; D006801:Humans; D019047:Phantoms, Imaging; D010865:Pilot Projects; D011874:Radiometry / Q000295:instrumentation*; D011879:Radiotherapy Dosage; D012666:Semiconductors