Radiobiological model comparison of 3D conformal radiotherapy and IMRT plans for the treatment of prostate cancer

Abstract

The main aim of radiotherapy is to deliver a dose of radiation that is high enough to destroy the tumour cells while at the same time minimising the damage to normal healthy tissues. Clinically, this has been achieved by assigning a prescription dose to the tumour volume and a set of dose constraints on critical structures. Once an optimal treatment plan has been achieved the dosimetry is assessed using the physical parameters of dose and volume. There has been an interest in using radiobiological parameters to evaluate and predict the outcome of a treatment plan in terms of both a tumour control probability (TCP) and a normal tissue complication probability (NTCP). In this study, simple radiobiological models that are available in a commercial treatment planning system were used to compare three dimensional conformal radiotherapy treatments (3D-CRT) and intensity modulated radiotherapy (IMRT) treatments of the prostate. Initially both 3D-CRT and IMRT were planned for 2 Gy/fraction to a total dose of 60 Gy to the prostate. The sensitivity of the TCP and the NTCP to both conventional dose escalation and hypo-fractionation was investigated. The biological responses were calculated using the Källman S-model. The complication free tumour control probability (P+) is generated from the combined NTCP and TCP response values. It has been suggested that the alpha/beta ratio for prostate carcinoma cells may be lower than for most other tumour cell types. The effect of this on the modelled biological response for the different fractionation schedules was also investigated.

Evaluation of various common prostate IMRT techniques based on estimated tumor control and normal tissue complication probabilities in correlation with patients anatomical parameters derived from the CT scans

“…It should be noted that the femur heads NTCP values were very low, therefore we did not report the results of this structure assuring no remarkable bone damage in all of the techniques. In addition, previous results support our claim [6,8].…”

“…We evaluated and compared the radiobiological results of four various IMRT techniques in different ranges of anatomical parameters. In the previous studies [4][5][6][7][8][9][10], comparison of IMRT radiotherapy techniques with other methods have been investigated from the perspective of radiobiological effects. Nevertheless, different IMRT techniques have not been conclusively compared.…”

“…The dose volume histograms (DVHs) of OARs and CTV for the IMRT plans of each patient were entered in the BioSuite software [18]. The TCP and NTCP were calculated for the CTV and OARs respectively using the relative seriality model [16] using radiobiological model parameters from the study by Deb and Fielding [6]. The P + was calculated from the TCP and overall NTCP.…”

“…Intensity modulated radiotherapy (IMRT), as a one of most usable techniques [3], is used to deliver prescribed dose to the target tissue and spare OARs from irradiation. The preference of IMRT on conventional and conformal techniques has been proven in previous studies [4][5][6][7]. In addition, IMRT has indicated similar or just a little worse radiobiological and dosimetric results in comparison with newer radiotherapy techniques, like the volumetric modulated radiotherapy, tomotherapy and intensity modulated arc therapy [8][9][10].…”

Nanovectorized radiotherapy: a new strategy to induce anti-tumor immunity

“…These new approaches allow obtaining more conformal “radio-ablative” treatment of tumor lesions while minimizing the damage to the nearby normal tissues (Deb and Fielding, 2009; Teoh et al, 2011; Yu and Tang, 2011; Wen et al, 2012). …”