A study of the effect of the lung shape on the lung absorbed dose in six standard photon and neutron exposure geometries

Abstract

-According to the published results of radiation dosimetry studies, there are significant discrepancies in the organ absorbed doses of existing adult male phantoms. As stated, differences in the organ absorbed doses may be associated with the variations in the organs' volumes, shapes and positions in the body frame. Therefore, this paper focuses on the effect of the lung shape on the lung absorbed dose by creating a series of voxel phantoms, in which the lung shape follows a statistical distribution. These phantoms were exposed to mono-energetic photons and neutrons in six standard irradiation geometries. The results show that when the phantom is irradiated by the low-energy photons, the effects of the lung shape on the lung absorbed dose are considerable (with an uncertainty of more than 100%). For the other irradiation conditions, the variation in the lung shape causes an uncertainty of less than 10% in the dose delivered to the lung.

Studying the lung dose uncertainty during chest CT scans using phantoms with statistical lung volumes and shapes

“…To validate this assumption, Ebrahimi-Khankook et al have given some clues in their recent work, which proved that using a similar wholebody frame for phantoms with different lung size/shape would be an acceptable assumption [13]. Therefore, commencing the AM phantom, two series of statistical phantoms have been developed as described in previous works [12,13].…”

“…Among them, 70 series were chosen, which belong to normal patients without any disease and/or fracture in the chest area that may change the shape of the lung and rib cage. Lung shape diversity was another parameter used to select the series, so that the full range of lung shapes was considered for the assessment of variations [12]. Some of the chosen lungs are shown in figure 2.…”

“…Fixing other effective parameters such as whole-body properties and legs and arms statuses, two series of deformable phantoms with statistical lung size and shape were developed and the influences of lung shape and lung size discrepancies on the lung dose were studied in standard irradiation geometries in these works. Obtained results indicated that the lung absorbed dose is strongly related to organ size and shape for low-energy photon sources [12,13].…”

Studying the effects of the lung mass on the absorbed dose to the lung due to the administration of131I for therapeutic purposes

“…Tomography images and the samples acquired from human corpses are indicative of the fact that the size, shape and positions of human organs are significantly different from one person to another. These deviations have not been considered in h_sajadi@pnu.ac.ir the current models (Mofrad et al, 2010;Ebrahimi-Khankook et al, 2015). It is very important to investigate to what degree this anatomical difference can affect the deviation of the absorbed dose.…”

Evaluating the effects of statistical changes on internal dosimetry

“…In dosimetric calculations of internal radiation therapy, reference phantoms are used, which are developed based on the anatomical data of 50th percentiles of a population (ICRP, 1975(ICRP, , 2002Xu and Eckerman, 2009). According to the tomographic images, the shapes and sizes of internal organs of the human body differ significantly from one person to another (Mofrad et al, 2010;Ebrahimi-Khankook et al, 2015). There are many reference phantoms developed by different groups and some sets of patient-dependent phantoms.…”