VOA标准英语2010-Doctors Debate Benefits, Risks of Virtual

Scientists at the U.S. Food and Drug Administration disagree about the risks from CT scans given during virtual colonoscopies. Doctors who favor the procedure say it is less invasive and more cost effective than a conventional colonoscopy. Those against it say the CT scans expose patients to too much radiation.

Colon¹ cancer is one of the world's deadliest diseases, but it often has no symptoms in the early stages. That's why doctors urge adults over 50 to have a colonoscopy to detect any possible cancer.

Conventional colonoscopy is performed with a long, flexible tube called a colonoscope that is equipped with a tiny fiber-optic video camera and light at the end. The colonoscope is inserted into a patient's colon. Doctors can see the images from the colonoscope on a video monitor. They can also remove any abnormal growths or polyps during the procedure.

 

A less invasive procedure known as a virtual colonscopy is done with a CT scan that passes x-rays through a patient's abdomen².

Dr. Mahadevappa Mahesh, a professor of Radiology and Medicine at Johns Hopkins University School of Medicine, says virtual colonoscopies can save the lives of many patients. "(A) lot of the time patients (are) not coming to the clinic after they talk to their doctors (about conventional colonoscopy). They see the invasiveness involved. They get scared. They might not get anything done. They might end up getting cancer," he said. Virtual colonoscopy as a screening tool is quite effective thats one of the reason why national cancer Institute recommends this as one of the screening device."

If growths or polyps are found during a virtual colonscopy, then a conventional colonoscopy must be done to remove them.
But some doctors say the CT scan exposes patients unnecessarily to harmful radiation, as much radiation as a patient might receive from 400 chest x-rays.

Dr. Julian Nicholas is a scientist, formerly³ with the Food and Drug Administration (FDA). He says arguments for virtual colonoscopy are not sound. "There was an absence of sufficient valid⁴ scientific evidence that the use of CT devices for colorectal cancer is both safe and effective," he said.

Dr. Nicholas says before he left the FDA, he and other scientists warned against the routine use of CT scans. "FDA physicians and scientists were ridiculed⁵ and chastized for raising the bugaboo (fearful image) of radiation."

Dr. Jeffrey Shuren from the FDA agrees that patients may not be fully⁶ aware of the risks involved in a virtual colonoscopy.
"What we assure is that the technologies that do come on the market are safe and effective, but whether or not they should be used on a given case, a given patient, is a decision that is made by the individual practitioner," he said.

But with 70 million CT scans being performed in the U.S. every year, the government is under pressure to make an official recommendation on how much radiation is safe during a CT scan.

This report is narrated⁷ by Carol Pearson.
 

1 colon   

n.冒号，结肠，直肠

参考例句：

• Here,too,the colon must be followed by a dash.这里也是一样，应当在冒号后加破折号。
• The colon is the locus of a large concentration of bacteria.结肠是大浓度的细菌所在地。

2 abdomen   

n.腹，下腹(胸部到腿部的部分)

参考例句：

• How to know to there is ascarid inside abdomen?怎样知道肚子里面有蛔虫？
• He was anxious about an off-and-on pain the abdomen.他因时隐时现的腹痛而焦虑。

3 formerly   

adv.从前，以前

参考例句：

• We now enjoy these comforts of which formerly we had only heard.我们现在享受到了过去只是听说过的那些舒适条件。
• This boat was formerly used on the rivers of China.这船从前航行在中国内河里。

4 valid   

adj.有确实根据的；有效的；正当的，合法的

参考例句：

• His claim to own the house is valid.他主张对此屋的所有权有效。
• Do you have valid reasons for your absence?你的缺席有正当理由吗？

5 ridiculed   

v.嘲笑，嘲弄，奚落( ridicule的过去式和过去分词 )

参考例句：

• Biosphere 2 was ultimately ridiculed as a research debade, as exfravagant pseudoscience. 生物圈2号最终被讥讽为科研上的大失败，代价是昂贵的伪科学。 来自《简明英汉词典》
• She ridiculed his insatiable greed. 她嘲笑他的贪得无厌。 来自《简明英汉词典》

6 fully   

adv.完全地，全部地，彻底地；充分地

参考例句：

• The doctor asked me to breathe in,then to breathe out fully.医生让我先吸气，然后全部呼出。
• They soon became fully integrated into the local community.他们很快就完全融入了当地人的圈子。

7 narrated   

v.故事( narrate的过去式和过去分词 )

参考例句：

• Some of the story was narrated in the film. 该电影叙述了这个故事的部分情节。 来自《简明英汉词典》
• Defoe skilfully narrated the adventures of Robinson Crusoe on his desert island. 笛福生动地叙述了鲁滨逊·克鲁索在荒岛上的冒险故事。 来自《现代汉英综合大词典》