Screen Test
1. Every year millions of women are screened with X-rays to pick up signs of breast cancer. If this happens early enough, the disease can often be treated successfully. According to a survey (调查)published last year, 21 countries have screening programmes. Nine of them, including Australia, Canada, the US and Spain, screen women under 50.
2. But the medical benefits of screening these younger women are controversial(有争议的), partly because the radiation(辐射) brings a small risk of inducing cancer. Also, younger women must be given higher doses of X-rays because their breast tissue(组织) is denser.
3. Researchers at the Polytechnic University1 of Valencia analysed the effect of screening more than 160,000 women at 11 local clinics. After estimating the women’s cumulative dose of radiation, they used two models to calculate the number of extra cancers this would cause.
4. The mathematical model recommended by Britain’s National Radiological Protection Board (NRPB) predicted that the screening programme would cause 36 cancers per 100,000 women, 18 of them fatal. The model preferred by the UN Scientific Committee on the Effects of Atomic Radiation led to a lower figure of 20 cancers.
5. The researchers argue that the level of radiation-induced cancers is “not very significant” compared to the far larger number of cancers that are discovered and treated. The Valencia programme, they say, detects between 300 and 450 cases of breast cancer in every 100,000 women screened.
6. But they point out that the risk of women contracting cancer from radiation could be reduced by between 40 and 80 percent if screening began at 50 instead of 45, because they would be exposed to less radiation. The results of their study, they suggest, could help “optimize the technique” for breast cancer screening.
7. “There is a trade-off(平衡) between the diagnostic(诊断的，判断的) benefits of breast screening and its risks,” admits Michael Clark of the NRPB. But he warns that the study should be interpreted with caution. “On the basis of the current (目前的)data, for every 10 cancers successfully detected and prevented there is a risk of causing one later in life. That’s why radiation exposure should be minimized in any screening programme.”
练习：
1. Paragraph2 ________
2. Paragraph3 ________
3. Paragraph4 _ ____
4. Paragraph5 _____
A. Harm Screening May Do to a Younger Woman
B. Investigating (调查)the Effect of Screening
C. Effects Predicted by Two Different Models
D. Small Risk of Inducing Cancers from Radiation
E. Treatment of Cancers
F. Factors That Trigger Cancers
5.Early discovery of breast cancer may________.
6.Advantages of screening women under 50 are _______.
7.Delaying the age at which screening starts may ________.
8.Radiation exposure should be ________.
A. be costly
B. harmful
C. save a life
D. still open to debate(争论)
E. reduce the risk of radiation triggering a cancer
F. reduced to the minimum
答案与题解：
1.A A说^是：用X射线检查可能对年轻女人不好。下面是第二段讲的意思：但是，用X射 线检查年轻女性，就医学上的好处而论，是有争议的，部分原因是辐射有诱发癌症的小小的 危险。另外，年轻女人****组织紧密，给予的X射线的剂量要多一些。
2.B B说的是：调查用X射线检查的结果。第三段的第一句话是这么说的:Valencia理工大 学的研究人员分析了 11个社区诊所用X射线检査16万以上女性的结果。可见B为正确的 选项。
3.C C说的是：两种不同的模型预测的结果。第四段讲的是，两种不同的数学模型在预测用 X射线检查女性诱发癌症的结果是不一样的。C概述了这段话。
4.D D说的是：辐射诱发癌症的危险是很小的。第五段的第一句话是这么说的：The researchers argue that the level of radiation-induced cancers is “ not very significant" compared to the far larger number of cancers that are discovered and treated.研究人员争辩说，与发现后 接受治疗的癌症数字相比，由辐射诱发癌症的数字是很小的。
5.C C与题干生成:Early discovery of breast cancer may save a life.乳腺癌发现得早也许能挽 救生命。答案可以从第一段中找到。
6.D D 与题干生成:Advantages of screening women under 50 are still open to debate. X才 50 岁 以下的女人用X射线捡查的好处仍然是有争议的。第二段的第一个甸子是这么说的:But the medical benefits of screening these younger women are controversial...但是，用 X 射线检查 年轻女性，就医学上的好处而论，是有争议的……这两个句子用词有些差别，但基本意思是相同的。
7.E E 与题干生成：Delaying the age at which screening starts may reduce Ihe risk of radiation triggerhig^a cancer.延纤用X射线检查的年龄也许能减少辐射诱发的危险。答案在第
8.F F与题干生成扭tion exposu诹命cmld be reduced to the minimum.应把接受辐射降低到最小的程度。答案在文章的最后一句。
