Biological dose volume histograms during conformal hypofractionated accelerated radiotherapy for prostate cancer

Koukourakis, Michael I.; Abatzoglou, Ioannis; Touloupidis, Stavros; Manavis, Ioannis

doi:10.1118/1.2401655

Cited by 8 publications

(9 citation statements)

References 33 publications

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“…These results are in agreement with the reported induction of the promoter by UV‐exposure in HeLa cells 27. Rapid induction of the t‐PA promoter again suggests its potential in novel hypofractionated or accelerated protocols, where multiple daily fractions are delivered and rapid transgene expression would be required 47, 48.…”

Section: Discussionmentioning

confidence: 99%

The tissue plasminogen activator gene promoter: a novel tool for radiogenic gene therapy of the prostate?

Marignol

Robson

McCarthy

et al. 2008

The Journal of Gene Medicine

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Section: Discussionmentioning

confidence: 99%

The tissue plasminogen activator gene promoter: a novel tool for radiogenic gene therapy of the prostate?

Marignol

Robson

McCarthy

et al. 2008

The Journal of Gene Medicine

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“…Only the SDs for the RWTD calculated with RBE = 1 in standard fractionations have Koukourakis et al (2007). e Fowler (2005).…”

Section: Resultsmentioning

confidence: 99%

Clinical consequences of relative biological effectiveness variations in proton radiotherapy of the prostate, brain and liver

et al. 2013

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Proton relative biological effectiveness (RBE) is known to depend on the (α/β) x of irradiated tissues, with evidence of ∼60% variation over (α/β) x values from 1-10 Gy. The range of (α/β) x values reported for prostate tumors (1.2-5.0 Gy), brain tumors (10-15 Gy) and liver tumors (13-17 Gy) imply that the proton RBE for these tissues could vary significantly compared to the commonly used generic value of 1.1. Our aim is to evaluate the impact of this uncertainty on the proton dose in Gy(RBE) absorbed in normal and tumor tissues. This evaluation was performed for standard and hypofractionated regimens. RBE-weighted total dose (RWTD) distributions for 15 patients (five prostate tumors, five brain tumors and five liver tumors) were calculated using an in-house developed RBE model as a function of dose, dose-averaged linear energy transfer (LET d ) and (α/β) x . Variations of the dose-volume histograms (DVHs) for the gross tumor volume (GTV) and the organs at risk due to changes of (α/β) x and fractionation regimen were calculated and the RWTD received by 10% and 90% of the organ volume reported. The goodness of the plan, bearing the uncertainties, was then evaluated compared to the delivered plan, which considers a constant RBE of 1.1. For standard fractionated regimens, the prostate tumors, liver tumors and all critical structures in the brain showed typically larger RBE values than 1.1. However, in hypofractionated regimens lower values of RBE than 1.1 were observed in most cases. Based on DVH analysis we found that the RBE variations were clinically significant in particular for the prostate GTV and the critical structures in the brain. Despite the uncertainties in the biological input parameters when estimating RBE values, the results show that the use of a variable RBE with dose, LET d and (α/β) x could help to further optimize the target dose in proton treatment

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“…In our case, the fractionation of interest is 7.25 Gy per fraction in 5 fractions (total dose of 36.25 Gy). The NTD[71718] is given by…”

Section: Methodsmentioning

confidence: 99%

“…Koukourakis et al . [17] found the escalated dose within the prostate target which was treated by the conformal hypofractionated accelerated dose regimen. The objective of the present study is to analyze the cyberknife hypofractionated dose distribution in the 36.25 Gy in 5 fractions regimen in terms of the conventional equivalent NTDs to evaluate the degree of dose escalation possible in the localized prostate cancer.…”

Section: Introductionmentioning

confidence: 99%

Equivalent normalized total dose estimates in cyberknife radiotherapy dose delivery in prostate cancer hypofractionation regimens

et al. 2012

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As the α/β value of prostate is very small and lower than the surrounding critical organs, hypofractionated radiotherapy became a vital mode of treatment of prostate cancer. Cyberknife (Accuray Inc., Sunnyvale, CA, USA) treatment for localized prostate cancer is performed in hypofractionated dose regimen alone. Effective dose escalation in the hypofractionated regimen can be estimated if the corresponding conventional 2 Gy per fraction equivalent normalized total dose (NTD) distribution is known. The present study aims to analyze the hypofractionated dose distribution of localized prostate cancer in terms of equivalent NTD. Randomly selected 12 localized prostate cases treated in cyberknife with a dose regimen of 36.25 Gy in 5 fractions were considered. The 2 Gy per fraction equivalent NTDs were calculated using the formula derived from the linear quadratic (LQ) model. Dose distributions were analyzed with the corresponding NTDs. The conformity index for the prescribed target dose of 36.25 Gy equivalent to the NTD dose of 90.63 Gy (α/β = 1.5) or 74.31 Gy (α/β = 3) was ranging between 1.15 and 1.73 with a mean value of 1.32 ± 0.15. The D5% of the target was 111.41 ± 8.66 Gy for α/β = 1.5 and 90.15 ± 6.57 Gy for α/β = 3. Similarly, the D95% was 91.98 ± 3.77 Gy for α/β = 1.5 and 75.35 ± 2.88 Gy for α/β = 3. The mean values of bladder and rectal volume receiving the prescribed dose of 36.25 Gy were 0.83 cm3 and 0.086 cm3, respectively. NTD dose analysis shows an escalated dose distribution within the target for low α/β (1.5 Gy) with reasonable sparing of organs at risk. However, the higher α/β of prostate (3 Gy) is not encouraging the fact of dose escalation in cyberknife hypofractionated dose regimen of localized prostate cancer.

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Biological dose volume histograms during conformal hypofractionated accelerated radiotherapy for prostate cancer

Cited by 8 publications

References 33 publications

The tissue plasminogen activator gene promoter: a novel tool for radiogenic gene therapy of the prostate?

The tissue plasminogen activator gene promoter: a novel tool for radiogenic gene therapy of the prostate?

Clinical consequences of relative biological effectiveness variations in proton radiotherapy of the prostate, brain and liver

Equivalent normalized total dose estimates in cyberknife radiotherapy dose delivery in prostate cancer hypofractionation regimens

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