hrvatski

Uloga radiobioloških parametara tkiva u izradi radioterapijskog plana za radikalno ozračivanje prostate

The purpose of radiotherpay treatment planning is to deliver therpeutically dose on tumor and tolerant dose to surrounding health tissue. A relevant data about geometry and a kond of tissues are acquired by CT simulator. A treatment planning program XiO calculates absorbed dose in small part of tissue as 0.2 ccm. The dose limits, based on ckinical experience are published in terms of maximal permitted dose on part of the organ. A special tools based on radiobiological parameters of tissue are implemented in XiO to facilitate the reviewing of plans. TCP (Tumor Control Probability) model uses alpha parameter from LQ dose response model and predicts the behaviour of tumor mass after the treatment. The propesed value is alpha=0.44 but it is not found that the results of comparing different plans are better visible if a value alpha00.30 is used. For adenocarcinoma, the most frequently prostate tumor, TCP model is not sensitive for time parameters and density of tumor cells as well. NTCP (Normal Tissue Complication Probability) model gives a probability of complication or injury in dependence of total absorbed dose. A model proposed by Lyman, Kuthcer and Burman is used. The parameters are selected as the best fit to clinical data. Two examples are discussed. For the fixed beams positions and shapes the total dose was changed from 70 Gy to 80Gy in steps of 2 Gy. NTCP values for bladder are negligible but for rectum are increasing and become inacceptable. Compared are the plans for fixed dose value of 76Gy and different numbers of beams amd sahpes. The simple four fields technique named box, demonstarte the very well score both for TCP and NTCP comparing. The collaboration with radiobiological deoartment could be useful.

radioterapija; apsorbirana doza u tkivu; tumorsko tkivo prostate

nije evidentirano

engleski

The role of radiobiology tissue parameters in radiotherapy treatment planning for the radical irradiation of prostate

The purpose of radiotherpay treatment planning is to deliver therpeutically dose on tumor and tolerant dose to surrounding health tissue. A relevant data about geometry and a kond of tissues are acquired by CT simulator. A treatment planning program XiO calculates absorbed dose in small part of tissue as 0.2 ccm. The dose limits, based on ckinical experience are published in terms of maximal permitted dose on part of the organ. A special tools based on radiobiological parameters of tissue are implemented in XiO to facilitate the reviewing of plans. TCP (Tumor Control Probability) model uses alpha parameter from LQ dose response model and predicts the behaviour of tumor mass after the treatment. The propesed value is alpha=0.44 but it is not found that the results of comparing different plans are better visible if a value alpha00.30 is used. For adenocarcinoma, the most frequently prostate tumor, TCP model is not sensitive for time parameters and density of tumor cells as well. NTCP (Normal Tissue Complication Probability) model gives a probability of complication or injury in dependence of total absorbed dose. A model proposed by Lyman, Kuthcer and Burman is used. The parameters are selected as the best fit to clinical data. Two examples are discussed. For the fixed beams positions and shapes the total dose was changed from 70 Gy to 80Gy in steps of 2 Gy. NTCP values for bladder are negligible but for rectum are increasing and become inacceptable. Compared are the plans for fixed dose value of 76Gy and different numbers of beams amd sahpes. The simple four fields technique named box, demonstarte the very well score both for TCP and NTCP comparing. The collaboration with radiobiological deoartment could be useful.

radiotherapy; apsorbed dose; tumor mass; prostate

nije evidentirano