问题 多项选择题

关于CT机的矩阵的描述,正确的是()

A.图像分辨率受矩阵大小影响

B.矩阵大小影响细微结构显示能力

C.增加像素数可增加扫描的原始数据

D.增加像素数可改善重建分辨率

E.使用1024×1024矩阵的图像比512×512矩阵的图像像素数多一倍

答案

参考答案:A, B, D, E

解析:矩阵是像素以二维方式排列的阵列,它与重建后图像的质量有关。在相同大小的采样野中,矩阵越大像素也就越多,重建后图像质量越高。目前常用的采集矩阵大小基本为:512×512,另外还有256×256和1024×1024。CT图像重建后用于显示的矩阵称为显示矩阵,通常为保证图像显示的质量,显示矩阵往往是等于或大于采集矩阵。通常采集矩阵为512×512的CT,显示矩阵常为1024×1024。原始数据是CT扫描后由探测器接收到的信号,经模数转换后传送给计算机,其间已转换成数字信号经预处理后,尚未重建成横断面图像的这部分数据被称为原始数据。

阅读理解

Many young people in America go to camps when they are out of school during the summer. They are offered a chance to explore different things: nature, sports, music, technology ——even business and economy.

One such program for high school students in the Pacific Northwest is called Washington Business Week. The program began in 1975. Officials say forty-five thousand people have attended Washington Business Week. Other states now have similar camps.

Washington Business Week describes itself as a way to learn more about how to plan for the future in an ever-changing economy. Students form an executive(行政的) management (管理) team. They lead an imaginary company to financial success.

The camp is held at three colleges in Washington State. The high school students live in the college housing. The cost of the camp is almost three hundred dollars, but families can receive financial assistance(援助).

Some business camps are free. These are for students from poor areas. The National Foundation for Teaching Entrepreneurship(企业家)(NFTE) is an organization based in New York City that supports such camps. It has programs around the United States and its Web site lists international partners in China, Tanzania and a few other countries. NFTE says it has served more than one hundred thousand young people since 1987.

Among other business camps is Camp C.E.O.. C.E.O is an chief executive officer. And this camp is for girls only. Camp C.E.O. is supported by the Girl Scouts of America and takes place for one week each summer.

The camp took place last month in Tennessee. The girls worked with successful businesswomen

from different industries. The girls learned how to build a business and develop an idea into a product. And, we imagine, they also had some fun.

小题1: In Washington Business Week, students successfully run a company_______.

A.that they are working in

B.that belongs to the American government

C.that does not actually exist

D.that was once shut down小题2:Which of the following is True about NFTE?

A.It offers financial help to all students.

B.It has programs in America and some other countries.

C.It was organized by many rich New Yorkers.

D.One of its aims is to train students to be business managers.小题3:What can we conclude from the passage ?

A.The Americans are good at enjoying their lives in many camps.

B.The young Americans are living a happy life in camps.

C.The Americans pay attention to developing the students’ abilities.

D.It is easier to organize business camps in America than other countries.小题4:Which of the following is the best title of the passage?

A. Summer camps for students             B. Summer camps for future C.E.O.

C. Summer camps being popular           D. Summer camps in the world

单项选择题