A practical and accurate generalized in vivo dosimetry procedure has been implemented for Siemens linacs supplying 6, 10, and 15 MV photon beams, equipped with aSi electronic portal imaging devices (EPIDs). The in vivo dosimetry method makes use of correlation ratios between EPID transit signal, st 0(TPR,w,L), and phantom mid-plane dose, D0(TPR,w,L), as functions of phantom thickness, w, square field dimensions, L, and tissue-phantom ratio TPR20,10. The st 0(TPR,w,L) and D0(TPR,w,L) values were defined to be independent of the EPID sensitivity and monitor unit calibration, while their dependence on TPR20,10 was investigated to determine a set of generalized correlation ratios to be used for beams with TPR20,10 falling in the examined range. This way, other radiotherapy centers can use the method with no need to locally perform the whole set of measurements in solid water phantoms, required to implement it. Tolerance levels for 3D conformal treatments, ranging between ±5 and ±6% according to tumor type and location, were estimated for comparison purposes between reconstructed isocenter dose, Diso, and treatment planning system (TPS) computed dose Diso,TPS. Finally a dedicated software, interfaceable with record and verify (R&V) systems used in the centers, was developed to obtain in vivo dosimetry results in less than 2 min after beam delivery.

Fidanzio, A., Cilla, S., Azario, L., Piermattei, A., A generalized calibration procedure for in vivo transit dosimetryusing siemens electronic portal imaging devices, <<MEDICAL & BIOLOGICAL ENGINEERING & COMPUTING>>, 2011; 2011 (Gennaio): 373-383. [doi:10.1007/s11517-010-0699-6] [http://hdl.handle.net/10807/33070]

A generalized calibration procedure for in vivo transit dosimetry using siemens electronic portal imaging devices

Fidanzio, Andrea;Cilla, Savino;Azario, Luigi;Piermattei, Angelo
2011

Abstract

A practical and accurate generalized in vivo dosimetry procedure has been implemented for Siemens linacs supplying 6, 10, and 15 MV photon beams, equipped with aSi electronic portal imaging devices (EPIDs). The in vivo dosimetry method makes use of correlation ratios between EPID transit signal, st 0(TPR,w,L), and phantom mid-plane dose, D0(TPR,w,L), as functions of phantom thickness, w, square field dimensions, L, and tissue-phantom ratio TPR20,10. The st 0(TPR,w,L) and D0(TPR,w,L) values were defined to be independent of the EPID sensitivity and monitor unit calibration, while their dependence on TPR20,10 was investigated to determine a set of generalized correlation ratios to be used for beams with TPR20,10 falling in the examined range. This way, other radiotherapy centers can use the method with no need to locally perform the whole set of measurements in solid water phantoms, required to implement it. Tolerance levels for 3D conformal treatments, ranging between ±5 and ±6% according to tumor type and location, were estimated for comparison purposes between reconstructed isocenter dose, Diso, and treatment planning system (TPS) computed dose Diso,TPS. Finally a dedicated software, interfaceable with record and verify (R&V) systems used in the centers, was developed to obtain in vivo dosimetry results in less than 2 min after beam delivery.
Inglese
Fidanzio, A., Cilla, S., Azario, L., Piermattei, A., A generalized calibration procedure for in vivo transit dosimetryusing siemens electronic portal imaging devices, <<MEDICAL & BIOLOGICAL ENGINEERING & COMPUTING>>, 2011; 2011 (Gennaio): 373-383. [doi:10.1007/s11517-010-0699-6] [http://hdl.handle.net/10807/33070]
File in questo prodotto:
Non ci sono file associati a questo prodotto.

I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.

Utilizza questo identificativo per citare o creare un link a questo documento: http://hdl.handle.net/10807/33070
Citazioni
  • ???jsp.display-item.citation.pmc??? ND
  • Scopus ND
  • ???jsp.display-item.citation.isi??? ND
social impact