long99

作者：Fran Lowry  
出處：WebMD醫學新聞

　　December 2, 2009 (芝加哥) — 在一個大都市的1級創傷中心急診室進行的電腦斷層(CT)放射線曝露模式研究發現，診斷為腎結石和胰臟炎的病患最可能接受最高劑量的CT掃描放射線。
　　
　　加州大學舊金山分校、舊金山綜合醫院的Amita Kamath醫師在北美放射協會第95屆科學會議暨年會中表示，影像檢查累積的有效劑量資料應成為病患病歷記載的一部份。
　　
　　Kamath醫師在2006年10月至2007年3月間，研究因照CT而累積的放射線曝露，使用有效劑量估計以確認是否有某些人因影像檢查而處於較高放射量風險。
　　
　　聚焦在一般急診診斷－精神狀態改變、胰臟炎、腎結石、創傷－的回溯回顧中，她發現腎結石和胰臟炎病患最常反覆進行影像檢查，且放射線曝露劑量最高(50 mSv以上)。
　　
　　回顧的10,382名病患中，91人診斷為腎結石，61人診斷為胰臟炎。
　　
　　整體而言，此世代中有28%(2,890名病患)接受至少1次的CT掃描，20%到22%是創傷和精神狀態改變的病患，70%是胰臟炎病患，85%是腎結石病患。
　　
　　每位病患平均進行2次CT掃描。創傷和精神狀態改變病患為1.8次、腎結石病患1.4次、胰臟炎病患2.7次。
　　
　　Kamath醫師表示，整體而言，4%病患接受的劑量超過50 mSv。最常接受這麼高劑量的病患是腎結石和胰臟炎患者。
　　
　　她報告指出，腎結石病患接受CT掃描的機會是精神狀態改變病患的60倍以上(勝算比[OR]為64.6；95%信心區間[CI]為8.5- 493.1)，胰臟炎病患接受CT掃描的機會是精神狀態改變病患的20倍以上(OR為21.5；CI為7.5- 61.7)。在這段研究期間，腎結石病患接受超過50mSv之劑量的機會將近8倍(OR為7.9；CI為1.7- 36.0)。
　　
　　她向Medscape Radiology表示，我認為，這通常是因為他們發生併發症，例如偽囊腫或壞疽，因而使他們必須反覆進行影像檢查。
　　
　　這類病患需要追蹤檢查時，可以考量其他影像檢查方式，例如超音波和磁振造影。她表示，限制某段時間內的CT次數也可以限制曝露量。
　　
　　會議主持人、威斯康辛大學的Larry DeWerd博士向Medscape Radiology表示，我們早就瞭解CT放射線的風險，現在我們有了讓我們瞭解問題範圍的數據。
　　
　　他指出，提高警覺是好事，放射科醫師越謹慎，重複檢查就越少，或至少減少不必要的檢查。這是我希望的結果之一，當然，這需要時間，無法一蹴可及。
　　
　　威斯康辛大學附設醫院的J. Louis Hinshaw醫師加入他的看法，這是很有趣的研究，根據我的經驗，這並不意外。急診室使用CT情況大量增加，和過去5年相比的話更是如此。急診室需要進行CT的一個主要適應症是腎結石，如果陽性，通常會再進行一次追蹤檢查，有時候即造成放射線累積劑量大。
　　
　　他也同意應將放射線劑量納入病歷記載。
　　
　　這是個有可取之處的想法。要達到這類事情，總有一些障礙要克服，但是全國性的電子化病歷將可提高可能性。
　　
　　Kamath醫師與DeWerd博士以及 Hinshaw醫師皆宣告沒有相關財務關係。
　　
　　北美放射協會(RSNA)第95屆科學會議暨年會：摘要SSE22-06。發表於2009年11月30日。


Renal Stones, Pancreatitis Require High Radiation Doses to Diagnose in the ED

By Fran Lowry
Medscape Medical News

December 2, 2009 (Chicago, Illinois) — A study that looked at patterns of radiation exposure from computed tomography (CT) in the emergency department of a large urban level?1 trauma center found that patients who were diagnosed with renal stone disease and pancreatitis were the most likely to receive the highest exposure to radiation from CT scans.

Cumulative effective-dose data from imaging should become part of the patient's medical record, Amita Kamath, MD, from San Francisco General Hospital and the University of California at San Francisco, said here at the Radiological Society of North America 95th Scientific Assembly and Annual Meeting.

Dr. Kamath studied cumulative exposure to radiation from CT between October 2006 and March 2007 using effective-dose estimates to determine if certain patient populations were at risk for higher levels of imaging studies and radiation.

Focusing on a retrospective review of common emergency department diagnoses — altered mental status, pancreatitis, renal stone disease, and trauma, she found that renal stone disease and pancreatitis patients had the most repeat imaging and the highest radiation exposure (50?mSv or more).

Among the 10,382 patients reviewed, 91 patients were diagnosed with renal stone disease and 61 with pancreatitis.

Overall, 28% of the cohort (2890 patients) underwent at least 1 CT scan. This ranged from 20% to 22% of patients with trauma and altered mental states, to 70% of patients with pancreatitis, to 85% of patients with renal stone disease.

A mean of 2 CT scans were performed on each patient. That number ranged from 1.8 in patients with trauma and altered mental states, to 1.4 in patients with renal stone disease, to 2.7 in patients with pancreatitis.

Overall, 4% of patients received in excess of 50?mSv. The patients most likely to receive such a high dose were those with renal stone disease and pancreatitis, Dr. Kamath said.

Patients with renal stone disease were over 60 times more likely to undergo a CT scan (odds ratio [OR], 64.6; 95% confidence interval [CI], 8.5?- 493.1) than were patients with altered mental status, and those with pancreatitis were 20 times more likely to undergo a CT scan than those diagnosed with altered mental states (OR, 21.5; CI, 7.5?- 61.7). Patients with renal stone disease were nearly 8 times more likely (OR, 7.9; CI, 1.7?- 36.0) to receive more than 50?mSv over the study period, she reported.

"I think this is often because they develop complications, such as pseudocysts or necrosis, and they end up having to get repetitive imaging," she told Medscape Radiology.

Alternative imaging modalities, such as ultrasound and magnetic resonance imaging, should be considered when such patients require a follow-up study. Limiting the number of phases within the CT itself would also limit exposure, she said.

"We have known about the risks of CT radiation exposure for a while," session moderator, Larry DeWerd, PhD, from the University of Wisconsin, Madison, told Medscape Radiology. "Now we have numbers to tell us the scope of the problem."

Heightened awareness is a good thing, he added. "The more awareness there is among radiologists, the fewer repeat exams, or at least the fewer unnecessary exams, there will be. Hopefully, this could be one of the outcomes, but of course it will take time. It won't happen overnight."

Weighing in with his opinion, J. Louis Hinshaw, MD, from the University of Wisconsin Hospital and Clinics, Madison, added: "This was very interesting work and not surprising in my experience. The use of CT in the [emergency department] has been increasing dramatically, even more so over the past 5 years or so. One of the main indications that 'needs CT in the [emergency department]' is renal stones and, if positive, there is often at least 1 follow-up examination performed, sometimes leading to large cumulative radiation doses."

He endorsed the suggestion that radiation dose should become part of the medical record.

"That is an idea that certainly has merit. There are many obstacles to overcome in order to accomplish something like that, but a national electronic medical record could make something like that possible."

Dr. Kamath, Dr. DeWerd, and Dr. Hinshaw have disclosed no relevant financial relationships.

Radiological Society of North America (RSNA) 95th Scientific Assembly and Annual Meeting: Abstract SSE22-06. Presented November?30, 2009.