Dose distribution verifications of IMRT for NPC

Abstract

In order to explore a dose distribution verification procedure of intensity modulated radiation therapy (IMRT) for nasopharyngeal carcinoma (NPC) and establish its evaluation criteria, we performed 35 two-dimensional (2D) patient-specific IMRT verifications over the year 2006. The percent of pixels passing gamma and the normalized agreement test (NAT) index were mainly used to represent the agreement between the measured and computed dose distributions with three criteria (2%/2 mm, 3%/3 mm and 5%/3 mm) as recommended in the literature. The results were that all cases passed through verifications with three criteria except that the NAT index of one case was beyond the limitation, and the three tolerance levels of 2%/2 mm, 3%/3 mm and 5%/3 mm produced similar clinical verification results but led to different percent of pixels passing gamma and NAT index. Our data showed that the percent of pixels passing gamma and the NAT index were complementary to evaluate future IMRT verifications as two significant metrics. Due to the influence of the noise and the trait of the software, we considered an IMRT plan as acceptable in case of the percent of pixels passing gamma >95% and the NAT index <5 with the 5%/3 mm criteria for IMRT patient-specific quality assurance (QA).

Dose verification of intensity modulated radiotherapy in head and neck tumors

“…Each of these criteria has been suggested elsewhere. 2,7,21,22 The choice of the criteria is made so that as much information as possible can be obtained and observed. The dose differences between measured dose (in Linac) and calculated dose (in TPS) are evaluated while suppressing the dose of 10%, 20% or 30% from dose distribution.…”

Study on the heat transfer performance of heat exchange surfaces and flow channels under negative pressure

“…Previous studies on heat transfer processes have mostly been conducted at atmospheric pressure, with limited research conducted under negative or low-pressure conditions. Li et al [9][10][11] conducted experimental, simulation, and theoretical analyses to investigate the heat transfer performance and driving comfort of heat exchangers under different pressures. The study by Li et al 9 investigated the heat transfer performance of radiators under different atmospheric pressures and revealed the signicant inuence of atmospheric pressure on the convective heat transfer coefficient on the air side through theoretical analysis.…”

“…Li et al [9][10][11] conducted experimental, simulation, and theoretical analyses to investigate the heat transfer performance and driving comfort of heat exchangers under different pressures. The study by Li et al 9 investigated the heat transfer performance of radiators under different atmospheric pressures and revealed the signicant inuence of atmospheric pressure on the convective heat transfer coefficient on the air side through theoretical analysis. Despite the study's theoretical insights, it requires experimental validation to corroborate its ndings.…”

Fingerprint profiling of polysaccharides from different parts of lotus root varieties

“…Previous research studies have indicated that lotus root polysaccharides (LRPs) possess antioxidant, antidiabetic, antiobesity, antilipidemic and immunomodulatory activities and that they would have high value in the commercial development of functional food and medicine. 3,9,10 Quality control is considered to be the main issue in the commercialization process of functional polysaccharide products. 11 So far, little is known about the quality control of LRPs.…”