α/β ratio: A dose range dependence study

Garcia, Lourdes M.; Wilkins, David E.; Raaphorst, G. P.

doi:10.1016/j.ijrobp.2006.10.017

Cited by 42 publications

(35 citation statements)

References 27 publications

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“…This agrees with previous work that if indeed the DE is lower than previously thought then increasing the dose/fraction would be radiobiologically advantageous 20 . It confirms that if DE is really lower than expected, better tumour control should be achieved by fewer fractions but a larger dose/fraction 14,16,33 . To test this further four different published hypo-fractionation trials (listed in table 3) for prostate cancer were investigated.…”

Section: Tcp As a Function Of Dementioning

confidence: 54%

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

Deb

Fielding

2009

Australas. Phys. Eng. Sci. Med.

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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.

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Section: Tcp As a Function Of Dementioning

confidence: 54%

“…There is an increasing body of evidence that prostate cancer cells behave as a late reacting tissue and therefore the DE value for prostate cancer cells could have a value as low as 1 to as high as 5 [14][15][16][17][18][19][20] . This is in sharp contrast to the accepted value of 10 for most tumours.…”

Section: Introductionmentioning

confidence: 99%

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

Deb

Fielding

2009

Australas. Phys. Eng. Sci. Med.

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“…Thus vascular damage and immunological effects may increase the antitumoural efficacy of large doses [7]–[9]. On the other hand, the surviving fraction of cells after high doses may be higher than predicted by the continuously downward bending curve described by the linear-quadratic (L-Q) model for cell inactivation [10]. Indeed, the dose range for which this model can be used is a matter of debate [8], [11].…”

Section: Introductionmentioning

confidence: 99%

The Biological Effect of Large Single Doses: A Possible Role for Non-Targeted Effects in Cell Inactivation

et al. 2014

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Background and PurposeNovel radiotherapy techniques increasingly use very large dose fractions. It has been argued that the biological effect of large dose fractions may differ from that of conventional fraction sizes. The purpose was to study the biological effect of large single doses.Material and MethodsClonogenic cell survival of MCF7 and MDA-MB-231 cells was determined after direct X-ray irradiation, irradiation of feeder cells, or transfer of conditioned medium (CM). Cell-cycle distributions and the apoptotic sub-G1 fraction were measured by flow cytometry. Cytokines in CM were quantified by a cytokine antibody array. γH2AX foci were detected by immunofluorescence microscopy.ResultsThe surviving fraction of MCF7 cells irradiated in vitro with 12 Gy showed an 8.5-fold decrease (95% c.i.: 4.4–16.3; P<0.0001) when the density of irradiated cells was increased from 10 to 50×103 cells per flask. Part of this effect was due to a dose-dependent transferrable factor as shown in CM experiments in the dose range 5–15 Gy. While no effect on apoptosis and cell cycle distribution was observed, and no differentially expressed cytokine could be identified, the transferable factor induced prolonged expression of γH2AX DNA repair foci at 1–12 h.ConclusionsA dose-dependent non-targeted effect on clonogenic cell survival was found in the dose range 5–15 Gy. The dependence of SF on cell numbers at high doses would represent a “cohort effect” in vivo. These results support the hypothesis that non-targeted effects may contribute to the efficacy of very large dose fractions in radiotherapy.

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“…We conducted a custom literature search in order to collect measured or calculated α, β and α/β ratios for different cell types and organs versus energy [103][104][105][106][107][108][109][110][111][112][113]. The goals was to link differences of SER and RBE values versus energy, and explain discrepancies between the calculated and simulated DERs and the measured RBE and SER of different cell lines.…”

Section: I4f Der Vs Rbe and Sermentioning

confidence: 99%

“…The goals was to link differences of SER and RBE values versus energy, and explain discrepancies between the calculated and simulated DERs and the measured RBE and SER of different cell lines. Energy ranges varied from low dose rate brachytherapy sources (I-125 and Pb-103) [104,110,112], high dose rate brachytherapy sources (Ir-192) [108], 250 kVp x-ray sources [103,113], external MV beams [105 -107, 109, 111, 112]. All these studies used different cell lines, organs and tissues both from humans and animals.…”

Section: I4f Der Vs Rbe and Sermentioning

confidence: 99%

Monte Carlo simulation of modern techniques of intensity modulated radiation therapy (IMRT)

Tsiamas¹,

Τσιάμας²

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α/β ratio: A dose range dependence study

Cited by 42 publications

References 27 publications

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

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

The Biological Effect of Large Single Doses: A Possible Role for Non-Targeted Effects in Cell Inactivation

Monte Carlo simulation of modern techniques of intensity modulated radiation therapy (IMRT)

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