Correlation of 3D-planned and measured dosimetry of photon and electron craniospinal radiation in a pediatric anthropomorphic phantom.
OBJECTIVE
Improved radiotherapy techniques in pediatric craniospinal therapy (CSRT) strive to reduce risks of late morbidity. Using a pediatric anthropomorphic phantom, this research correlated measured target and normal tissue dose to that predicted from a 3D planning system (3D-RTP).


METHODS
A pediatric anthropomorphic phantom was planned following French Society of Pediatric Oncology (SFOP) protocols. Thermoluminescent detectors (TLDs) were used to perform dosimetric measurements during treatment. 4 and 6MV photon fields with multi leaf collimation (MLC) or custom blocks were compared to 3D-RTP computer (ADAC Pinnacle) predictions for cranial fields. Spinal dosimetry was studied using photons (4 and 6MV) and electrons (9 and 12MeV).


RESULTS
3D-RTP predictions generally concurred with dose received in cranial and spinal sites. The measured dose was over-predicted significantly by the 3D-RTP in the anterior cranial fossa. Normal tissue doses were reduced when treating the spine using megavoltage electron beams instead of photons.


CONCLUSIONS
Treating the spinal field with electrons minimises the risk of pulmonary sequelae, however electron energy selection is critical to achieve adequate spinal field coverage. Despite adhering to a major trial protocol guideline, dose at the floor of the anterior cranial fossa remains a potential clinical problem and 3D-RTP do not predict this well.
Hood
Claire
C
Department of Radiation Oncology, Newcastle Mater Hospital, NSW, Australia. claire.hood@mater.health.nsw.gov.au
Kron
Tomas
T
Hamilton
Chris
C
Callan
Scott
S
Howlett
Steve
S
Alvaro
Frank
F
Back
Michael
M
D000886:Anthropometry; D016477:Artifacts; D002528:Cerebellar Neoplasms / Q000532:radiotherapy*; D002675:Child, Preschool; D004583:Electrons; D006801:Humans; D008527:Medulloblastoma / Q000532:radiotherapy*; D017785:Photons; D011832:Radiation Injuries / Q000517:prevention & control*; D020266:Radiotherapy, Conformal / Q000379:methods*; D013819:Thermoluminescent Dosimetry / Q000379:methods*