OBJECTIVE: This study aims to evaluate efficacy of using a bismuth breast shield and optimized scanning parameter to reduce breast absorbed doses from CT thorax examination.
METHODS: Five protocols comprising the standard CT thorax clinical protocol (CP1) and four modified protocols (CP2 to CP5) were applied in anthropomorphic phantom scans. The phantom was configured as a female by placing a breast component on the chest. The breast component was divided into four quadrants, where 2 thermoluminescence dosimeters (TLD-100) were inserted into each quadrant to measure the absorbed dose. The bismuth shield was placed over the breast component during CP4 and CP5 scans.
RESULTS: The pattern of absorbed doses in each breast and quadrant were approximately the same for all protocols, where the 4th quadrant > 3rd quadrant > 2nd quadrant > 1st quadrant. The mean absorbed dose value in CP3 was reduced to almost 34% of CP1's mean absorbed dose. It was reduced even lower to 15% of CP1's mean absorbed dose when the breast shield was used in CP5.
CONCLUSION: This study showed that CT radiation exposure on the breast could be reduced by using a bismuth shield and low tube potential protocol without compromising the image quality.
METHODS: Search for related literature on salted fish,
smoking and alcohol consumption were performed via Science Direct, PubMed databases and Google Scholar. Articles
included in this study were from 2009 to 2017, with specific focus on salted fish, smoking and alcohol consumption
as risk factors of NPC. This study excluded all articles published prior to 2009 and articles involving other cancers.
Data were extracted independently by two different researchers and harmonized. Meta-analysis was conducted on the
obtained data, by using R package Meta to create funnel and forest plots.
RESULTS: The meta-analysis revealed that
salted fish, smoking and alcohol consumption were significantly associated to NPC risk with random effect model score
showing OR of 1.41 at 95% confidence interval (CI) of 1.13-1.75 (P<0.01), OR of 1.89 at 95 % CI of 1.49 - 2.38, and
OR: 1.42 at 95 % CI of 1.23 - 1.65 respectively. Our results also revealed significant association of salted meat, salted
vegetables, house type, wood dust exposure associated with NPC risk with p values less than 0.05.
CONCLUSION: This
study proposes that salted fish intake, smoking and alcohol consumption might be linked to NPC risk in Asians. Further
studies are necessary to ascertain the molecular mechanisms and clarify if the associated path that could function as
therapeutic target.