Clinical simulations of prostate radiotherapy using BOMAB-like phantoms: Results for photons

Saveta Miljanić (1) , Igor Bessières (2) , jean-marc bordy (2) , Francesco d'Errico (3) , Angela Di Fulvio (3) , Damian Kabat (4) , Željka Knežević (1) , Pawel Olko (5) , Liliana Stolarczyk (6) , Luigi Tana (7) , Roger Harrison (8)

1 Rudjer Boskovic Institute [Zagreb]
2 LNHB (CEA, LIST) - Laboratoire National Henri Becquerel (CEA, LIST)
3 University of Pisa - Università di Pisa
4 MCMCC - Maria Sklodowska-Curie Memorial Cancer Center and Institute of Oncology
5 H. Niewodniczanski Institute of Nuclear Physics
6 Niewodniczanski Institute of Nuclear Physics, Polish Academy of Sciences, 31-342 Krakow, Poland
7 Santa Chiara Hospital
8 Newcastle University [Newcastle]

In this part of work carried out by Working Group 9 (Radiation Protection Dosimetry in Medicine) of the European Radiation Dosimetry Group (EURADOS), water tank experiments described in this issue (Bordy et al., 2013) were extended to a BOMAB-like phantom. This phantom is more clinically realistic than a water tank, sufficiently to allow the simulation of some clinical treatments. In the experiments to be described, four types of prostate treatment were simulated: Volumetric Modulated Arc Therapy (VMAT, 6 MV), Tomotherapy (6 MV), IMRT (6 MV and 18 MV), 5-field conformal radiotherapy (15 MV) and 4-field conformal radiotherapy (6 MV and 18 MV). Irradiations were performed in two centres, University Hospital of Santa Chiara, Pisa, Italy and Centre of Oncology M. Skłodowska-Curie Memorial Institute, Krakow, Poland. Whatever the difficulties and uncertainties in risk estimation, its foundation lies in the knowledge of the absorbed dose to the irradiated organs. Thus the measurement of out-of-field doses is a crucial pre-requisite for risk estimation and is the subject of the EURADOS Working Group 9. For photon out-of-field dose measurements TLD, OSL and RPL dosimeters were used. Comparison of dosimeters under the same irradiation conditions showed that dosimeters generally agreed to within 3% compared with ion chamber reference measurements. Other comparisons were possible with these data. They include a comparison of doses (beam profiles) in different positions in the BOMAB phantom, a comparison of different treatment modalities in the two contributing clinical centres (Pisa and Krakow) and a comparison of dose profiles resulting from the different treatment techniques and the corresponding doses calculated by the treatment planning systems used to generate the treatment plans. Finally, preliminary measurements of surface doses at selected points on the trunk of the BOMAB phantom were made using diode detectors. Comparison of out-of-field doses for different modalities in the two clinical centres shows that differences in out-of-field doses for the same Planning Treatment Volume (PTV) can be even a factor of 4. For sparing adjacent organs-at-risk the best results were obtained for IMRT. On the other hand the lowest out-of-field doses were for MLC conformal therapy.

Mots clés: RPL; TLDT; IMRT; OSL; Out-of-field doses in radiotherapy; Photon dosimetry; omotherapy; VMAT; ABSORBED RADIATION DOSES; COMPARATIVE EVALUATIONS; COMPUTERIZED TOMOGRAPHY; CT-GUIDED RADIOTHERAPY; PHANTOMS; PHOTON BEAMS; RADIATION PROTECTION; BEAMS; DIAGNOSTIC TECHNIQUES; DOSES; EVALUATION; MEDICINE; MOCKUP; NUCLEAR MEDICINE; RADIATION DOSES; RADIOLOGY; RADIOTHERAPY; STRUCTURAL MODELS; THERAPY; TOMOGRAPHY

Domaines: Médecine nucléaire; Cancer; Physique Nucléaire Expérimentale [nucl-ex]

Saveta Miljanić, Igor Bessières, jean-marc bordy, Francesco d'Errico, Angela Di Fulvio, et al.. Clinical simulations of prostate radiotherapy using BOMAB-like phantoms: Results for photons. Radiation Measurements, 2013, 57, pp.35-47. ⟨10.1016/j.radmeas.2012.12.012⟩. ⟨cea-01815519⟩