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In current clinical practice, dose simulation in proton therapy planning is estimated from the tissue attenuation coefficients obtained with X-ray CT data and converted to relative stopping power (RSP) maps. However, as there is no unique relationship between Hounsfield units and RSP, this calibration step contributes to a range uncertainty margin which is between 2.5%+1mm and 3.5%+3mm depending on the proton center. Proton computed tomography (pCT) has the potential to improve the accuracy of the proton therapy treatment by a direct derivation of tissue-relative stopping power maps. Another potential benefit is the reduction of the imaging dose compared to X-ray CT since the energy loss of each proton can be measured and provides information about the patient tissues. Several studies have already demonstrated the capability of pCT to ...
Dans la pratique clinique actuelle, l'estimation de la dose délivrée dans le plan de traitement en protonthérapie se base sur une carte des coefficients d'atténuation reconstruite à partir d'une image par rayons X puis convertie en carte de pouvoir d'arrêt relatif (RSP). Cependant, comme il n'y a pas de relation unique entre les unités Hounsfield et le RSP, cette étape d'étalonnage impose d'augmenter les marges d'incertitudes sur le parcours des protons de l'ordre de 2.5%+1mm à 3.5%+3mm selon le centre de protonthérapie. L'imagerie proton (pCT) peut permettre une meilleure estimation de la dose délivrée en protonthérapie via une reconstruction directe de la carte de pouvoir d'arrêt des tissus. L'autre avantage de cette technique est de permettre une réduction de la dose délivrée pour l'acquisition des images en comparaison de l'imageri...
Proton therapy treatment efficiency directly relies on the proton range derived from tissue-relative stopping power (RSP) maps. In clinical practice, RSP is obtained from the conversion of X-ray CT Hounsfield units. This calibration step introduces uncertainties on the dose distribution. Proton computed tomography (pCT) has the potential to improve the accuracy of the proton therapy treatment by a direct derivation of RSP maps. This study aims to quantify the dosimetric accuracy of pCT. A full Monte Carlo proton therapy treatment planning has been developed. Both X-ray and proton CT images of a human computional phantom are simulated with an equivalent 2mGy dose. RSP maps are derived from both images and used to estimate the dose distribution. RSP maps derived from pCT are significantly more accurate and less sensitive to common X-ray ...
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