Radiation treatment dose optimisation using Poisson tumour control probability parameters

17th International Conference on the Use of Computers in Radiation Therapy

物理学;计算机科学

Cho, G.A.^1,2 ; Ebert, M.A.^3,4 ; Holloway, L.^2,5 ; Kuncic, Z.^2 ; Baldock, C.^6 ; Thwaites, D.I.^2

Department of Radiation Oncology, Royal Prince Alfred Hospital, Sydney Local Health District, Camperdown, NSW, Australia^1

Institute of Medical Physics, School of Physics, University of Sydney, Sydney, NSW, Australia^2

Radiation Oncology Department, Sir Charles Gairdner Hospital, Hospital Avenue, Nedlands, WA, Australia^3

School of Physics, University of Western Australia, Crawley, WA, Australia^4

Liverpool and Macarthur Cancer Therapy Centres, Sydney South Local Health District, Liverpool, NSW, Australia^5

Faculty of Science, Macquarie University, Sydney, NSW, Australia^6

关键词: Bivariate normal distributions;    Dose distributions;    Integral dose;    Linear quadratic;    Radiation treatments;    Treatment response;    Tumour control probabilities;    Volume elements;   

Others  :  https://iopscience.iop.org/article/10.1088/1742-6596/489/1/012047/pdf
DOI  :  10.1088/1742-6596/489/1/012047

学科分类：计算机科学（综合）

来源: IOP

【 摘 要 】

This study examines the Poisson tumour control probability (TCP) γ37and D37parameters of a uniformly irradiated numerical tumour model using changes in tumour burden as a surrogate for treatment response information. An optimum dose Difor a tumour sub-volume element Viis described that maximizes TCP as a function of fixed tumour integral dose ξ. TCP was calculated for spatially-varying clonogen density for a total 108cells and radiosensitivity α with mean radiosensitivity in the range 0.4-1.0 Gy-1. A bivariate normal distribution is used to describe the radiosensitivity α and the linear term of the linear-quadratic (LQ) cell kill governed the changes in the regional tumour burden within sub-volumes Vi. The optimum dose distribution, Di, for Viis obtained as a function of fixed tumour integral dose ξ. For a uniform dose delivery and for TCP = 37%, γ37and D37are described by the effective radiosensitivity αeffand the effective clonogen number N0,eff, respectively. αeffis equivalent to differential dose changes in the number of clonogenic cells (tumour burden). The γ37values were found to be inversely correlated with variance of the probability density function of the α distribution. For the biologically optimum dose distribution, γ37was found to converge to the theoretical maximum limit and D37was found to reduce relative to that obtained for the uniform dose case. The TCP parameters γ37and D37could thus be useful in optimising individual radiation treatment doses even when tumour heterogeneity is taken into account.