Microdosimetric study on influence of low energy photons on relative biological effectiveness under therapeutic conditions using 6 MV linac

Okamoto, Hiroyuki; Kohno, Toshiyuki; Kanai, Tatsuaki; Kase, Yuki; Matsumoto, Yoshitaka; Furusawa, Yoshiya; Fujita, Yukio; Saitoh, Hidetoshi; Itami, Jun

doi:10.1118/1.3613152

Cited by 19 publications

(16 citation statements)

References 29 publications

(31 reference statements)

Supporting

Mentioning

Contrasting

Order By: Relevance

“…The microdosimetric radiation quality γ is deduced from the y D value reported so far . The γ depends on radiation energy and type, but it has less depth‐dependence on y D value in water for a fixed 10 × 10 cm 2 field . Thus, the approximated y D value as in Table is used in the present study.…”

Section: Resultsmentioning

confidence: 99%

“…31 The c depends on radiation energy and type, but it has less depth-dependence on y D value in water for a fixed 10 9 10 cm 2 field. 43 Thus, the approximated y D value as in Table I is used in the present study. By using the mean values of the parameters in Table I, we described the cell survival curves for the LQM, MKM and MKM DR [using Eqs.…”

Section: A Cell Survival Curves In Consideration Of Doserate Effectsmentioning

confidence: 99%

See 1 more Smart Citation

Markov chain Monte Carlo analysis for the selection of a cell‐killing model under high‐dose‐rate irradiation

2017

View full text Add to dashboard Cite

show abstract

Section: Resultsmentioning

confidence: 99%

Section: A Cell Survival Curves In Consideration Of Doserate Effectsmentioning

confidence: 99%

Markov chain Monte Carlo analysis for the selection of a cell‐killing model under high‐dose‐rate irradiation

2017

View full text Add to dashboard Cite

show abstract

“…The survival curve for the 200-kV X-rays [16] was also plotted to derive experimental RBE values for the proton beams. If these survival curves were fitted by the linear quadratic model, then the fitted α and β values were, respectively, 0.157 Gy − 1 and 0.048 Gy − 2 at the entrance, 0.164 Gy − 1 and 0.048 Gy − 2 at 5 mm in the back of the proximal SOBP peak, 0.139 Gy − 1 and 0.056 Gy − 2 at the center of the SOBP, 0.141 Gy − 1 and 0.062 Gy − 2 at 5 mm short of the distal SOBP peak in the therapeutic proton beam and 0.196 Gy − 1 and 0.044 Gy − 2 for 200-kV X-rays.…”

Section: Resultsmentioning

confidence: 99%

“…The MKM was then modified to derive the RBE for particle- and energy-modulated beams from the microdosimetric spectrum measured using the tissue-equivalent proportional counter (TEPC) [15]. The MKM was often used for calculating the RBE distributions in combination with the Monte Carlo calculation for photon beams [16], passive carbon ion beams [17, 18] and scanning carbon ion beams [19]. …”

Section: Introductionmentioning

confidence: 99%

Microdosimetric calculation of relative biological effectiveness for design of therapeutic proton beams

Kase

Yamashita

Matsufuji³

et al. 2012

Journal of Radiation Research

View full text Add to dashboard Cite

The authors attempt to establish the relative biological effectiveness (RBE) calculation for designing therapeutic proton beams on the basis of microdosimetry. The tissue-equivalent proportional counter (TEPC) was used to measure microdosimetric lineal energy spectra for proton beams at various depths in a water phantom. An RBE-weighted absorbed dose is defined as an absorbed dose multiplied by an RBE for cell death of human salivary gland (HSG) tumor cells in this study. The RBE values were calculated by a modified microdosimetric kinetic model using the biological parameters for HSG tumor cells. The calculated RBE distributions showed a gradual increase to about 1cm short of a beam range and a steep increase around the beam range for both the mono-energetic and spread-out Bragg peak (SOBP) proton beams. The calculated RBE values were partially compared with a biological experiment in which the HSG tumor cells were irradiated by the SOBP beam except around the distal end. The RBE-weighted absorbed dose distribution for the SOBP beam was derived from the measured spectra for the mono-energetic beam by a mixing calculation, and it was confirmed that it agreed well with that directly derived from the microdosimetric spectra measured in the SOBP beam. The absorbed dose distributions to planarize the RBE-weighted absorbed dose were calculated in consideration of the RBE dependence on the prescribed absorbed dose and cellular radio-sensitivity. The results show that the microdosimetric measurement for the mono-energetic proton beam is also useful for designing RBE-weighted absorbed dose distributions for range-modulated proton beams.

show abstract

“…In this way, the details of the specific biological mechanisms of radiation effect were covered by nonspecific (statistically averaged) parameters over relatively wide time and spatial scales so that the inherent random fluctuations of Ionizing radiations as well as the radiobiological effects are negligible. Moreover, the increase in relative biological effectiveness (RBE) for low energy X-rays has been observed experimentally for a range of biological endpoints56. It is noted that the actual value of the RBE can vary in different parts of a patient or beam by an amount that is much larger than the tolerance for clinical treatment planning78.…”

mentioning

confidence: 98%

An Expanded Multi-scale Monte Carlo Simulation Method for Personalized Radiobiological Effect Estimation in Radiotherapy: a feasibility study

Zhang

Feng

Wang

et al. 2017

Sci Rep

View full text Add to dashboard Cite

A novel and versatile “bottom-up” approach is developed to estimate the radiobiological effect of clinic radiotherapy. The model consists of multi-scale Monte Carlo simulations from organ to cell levels. At cellular level, accumulated damages are computed using a spectrum-based accumulation algorithm and predefined cellular damage database. The damage repair mechanism is modeled by an expanded reaction-rate two-lesion kinetic model, which were calibrated through replicating a radiobiological experiment. Multi-scale modeling is then performed on a lung cancer patient under conventional fractionated irradiation. The cell killing effects of two representative voxels (isocenter and peripheral voxel of the tumor) are computed and compared. At microscopic level, the nucleus dose and damage yields vary among all nucleuses within the voxels. Slightly larger percentage of cDSB yield is observed for the peripheral voxel (55.0%) compared to the isocenter one (52.5%). For isocenter voxel, survival fraction increase monotonically at reduced oxygen environment. Under an extreme anoxic condition (0.001%), survival fraction is calculated to be 80% and the hypoxia reduction factor reaches a maximum value of 2.24. In conclusion, with biological-related variations, the proposed multi-scale approach is more versatile than the existing approaches for evaluating personalized radiobiological effects in radiotherapy.

show abstract

Microdosimetric study on influence of low energy photons on relative biological effectiveness under therapeutic conditions using 6 MV linac

Abstract: The increase of the RBE(MK) values by 6.6% outside the field was observed. This increase is caused by the change of the photon energy distributions, especially the increase of the relative number of low energy photons outside the field.

Cited by 19 publications

References 29 publications

Markov chain Monte Carlo analysis for the selection of a cell‐killing model under high‐dose‐rate irradiation

Markov chain Monte Carlo analysis for the selection of a cell‐killing model under high‐dose‐rate irradiation

Microdosimetric calculation of relative biological effectiveness for design of therapeutic proton beams

An Expanded Multi-scale Monte Carlo Simulation Method for Personalized Radiobiological Effect Estimation in Radiotherapy: a feasibility study

Contact Info

Product

Resources

About