Precise irradiation of locally advanced high-risk prostate cancer

Abstract

In radiotherapy of prostate cancer, it is very important to conform the irradiation fields as much as possible to target volume, i.e. to position the patient as accurately as possible, thereby allowing smaller safety margin. In this way, an optimal shielding for the organs at risk may be provided at a prescribed dose to the target volume.
Image-guided radiotherapy (IGRT) allows the reduction of the safety margin that accounts for the daily prostate movements. After the translation of prostate is subtracted, only the prostate rotation is to be considered. With the analysis of daily prostate rotation between the fractions of the first part of radiotherapy course, the safety margin can be optimized. Optimal size of the safety margin around the prostate may be used for the second and third part of the radiotherapy course and the radiotherapy plan may be adaped accordingly.

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Povzetek

Pri radioterapiji raka prostate je zelo pomembno oblikovati obsevalna polja tako, da se čim natančneje prilegajo volumnu, ki ga je treba obsevati. To pomeni, da moramo bolnika pri obsevanju čim natančneje nastaviti, saj s tem zmanjšamo potreben varnostni rob. Ob predpisani dozi na tarčni volumen bomo tako optimalno zaščitili kritične organe. Slikovno vodena radioterapija (IGRT) nam omogoča zmanjšanje varnostnega roba, ki zajema dnevna premikanja prostate. Ko z natančno nastavitvijo v marker upoštevamo translacijo prostate, moramo zajeti le še rotacijo prostate.
Z analizo dnevnih rotacij prostate med frakcijami prvega dela radioterapije lahko varnostni rob okoli prostate optimiziramo. Njegovo optimalno velikost lahko uporabimo za drugi in tretji del radioterapije in prilagodimo obsevalni načrt (adaptivna radioterapija).