External photon radiation treatment for prostate cancer: Uncomplicated and cancer-free control probability assessment of 36 plans

• Published in: Physica medica 2019-10, Vol.66, p.88-96
• Main Authors: Sánchez-Nieto, B., Romero-Expósito, M., Terrón, J.A., Irazola, L., García Hernández, M.T., Mateos, J.C., Roselló, J., Planes, D., Paiusco, M., Sánchez-Doblado, F.
• Format: Article
• Language: English
• Subjects: Humans; Male; Normal tissue complication probability; Photons - therapeutic use; Probability; Prostate radiotherapy treatment; Prostatic Neoplasms - diagnostic imaging; Prostatic Neoplasms - radiotherapy; Radiation protection of the patient; Radiobiological modelling; Radiotherapy Dosage; Radiotherapy plan optimisation; Radiotherapy Planning, Computer-Assisted - methods; Radiotherapy, Conformal; Radiotherapy, Intensity-Modulated; Second primary cancer risk; Tomography, X-Ray Computed; Tumour control probability
• ISSN: 1120-1797; 1724-191X
• DOI: 10.1016/j.ejmp.2019.09.076

•36 RT plans for PoCa were assessed by means of TCP, NTCP and second cancer risk.•SBRT techniques exhibited the lowest second cancer risk.•SPCR rates were low and small impact on plan ranking was shown.•Best plans were the10MV SBRTs.•High energy IMRT did not appear to increase in excess the second cancer risk. To perform a systematic and thorough assessment, using the Uncomplicated and Cancer-Free Control Probability (UCFCP) function, of a broad range of photon prostate cancer RT treatments, on the same scenario (a unique pelvic CT set). UCFCP considers, together with the probabilities of local tumour control (TCP) and deterministic (late) sequelae (NTCP), the second primary cancer risk (SPCR) due to photon and neutron peripheral doses. Thirty-six radiotherapy plans were produced for the same CT. 6, 10, 15 and 18 MV 3DCRT, IMRT and VMAT (77.4 Gy in 43 fractions) and 6 and 10 MV SBRT (36.25 Gy in 5 fractions with flattened and FFF beams) for Elekta, Siemens and Varian Linacs plans were included. DVH and peripheral organ dosimetry were used to compute TCP, NTCP, and SPCR (the competition and LNT models) for further plan ranking. Biological models (and parameters) used predicted an outcome which is in agreement with epidemiological findings. SBRT plans showed the lowest SPCR and a below average NTCPrectal. High energy plans did not rank worse than the low energy ones. Intensity modulated plans were ranked above the 3D conformal techniques. According to UCFCP, the best plans were the10 MV SBRTs. SPCR rates were low and did not show a substantial impact on plan ranking. High energy intensity-modulated plans did not increase in excess the average of SPCR. Even more, they ranked among the best, provided that MU were efficiently managed.