TORNA ALL’ELENCO

IGRT cone beam CT: A method to evaluate patient dose in Physica Medica

2016
AOU Città della Salute di Torino

Tipo pubblicazione

Conference Abstract

Autori/Collaboratori (7)Vedi tutti...

Giglioli F

Rampado O

Rossetti V


et alii...

Abstract

Introduction: The objective of the study was to calculate organ doses for several protocols of a radiotherapy cone beam equipment using the PCXMC software, validated comparing doses with TLDs. Furthermore a set of coefficients to provide an estimation of organ doses was assessed for patients of different genders and sizes. Materials and Methods: Dose evaluations were performed on an Elekta CBCT (XVI) for different protocols and acquisition parameters. The first part of the study investigated the opportunity to use PCXMC, a software based on Montecarlo simulation generally employed for projective radiology, for calculating organ doses. The software was adapted to better simulate the modulated filtration of this particular CBCT considering different filtered beam contributions. A set of 50 TLDs (Harshaw – TLD 100) was selected, irradiated and analysed, for each protocol, to compare measurements with PCXMC results. The influence of patient size on organ dose was evaluated varying heights, weights and genders. The organ doses were normalized to the PCXMC standard adult phantom doses and the calculated ratios were plotted versus the equivalent diameter of each patient size. Results: The differences between PCXMC and TLDs doses are generally below 10%; the respiratory airways and the prostate show a difference over 15%, probably as a consequence of their position at the boundaries of the beam, with a critical match of exposure geometry for actual and virtual anthropomorphic phantoms. Regarding simulations with patients of different heights, weights and genders, a variability in a range ±40% for pelvic region and ±30% for chest was observed; specifically, for the same acquisition protocol, organ doses for a slim patient could be much higher than the organ dose of an overweight patient. Conclusion: Our results confirm the validity of PCXMC with rotational module also for particular geometrical conditions; dose difference due to patient size can be evaluated consi

DOI : 10.1016/j.ejmp.2016.01.101

Keywords

radiology; prostate; obesity; imaging phantom; male; image guided radiotherapy; human; geometry; gender; filtration; female; drug megadose; controlled study; conference abstract; cone beam computed tomography; clinical evaluation; airway; adult; lithium fluoride; radiotherapy; simulation; software; thorax; validity;