ct的質(zhì)量控制ppt課件-免費(fèi)閱讀
【正文】 pelvis CT 8 11 mSv (800 1100 mrem) 腹部和骨盆 CT Average . background radiation 平均本底輻射 ? mSv (360 mrem) Effective dose values (cont.) 典型的有效劑量 Stereo chest xray mSv (10 mrem) 立體胸部 X線 Low dose chest CT mSv (70 mrem) 低劑量胸部 CT Mammogram mSv (180 mrem) 乳腺 CTC (5 mm) mSv (550 mrem) CTC (5 mm) Double contrast BE mSv (750 mrem) 增強(qiáng)對(duì)比 BE CTC ( mm) mSv (980 mrem) CTC ( mm) CT liver perfusion 15 mSv (1500 mrem) CT肝灌注 Why is MultiSlice CT Radiation Dose of Interest? 多層 CT輻射劑量的意義何在？ ? To evaluate different MS CT systems 評(píng)估不同的 CT系統(tǒng) ? To triage applications between MS and SS CT 在多層 CT與單層 CT之間進(jìn)行應(yīng)用比較 ? To design and optimize MS CT Protocols 設(shè)計(jì)和優(yōu)化多層 CT應(yīng)用方案 ? Tradeoff: Thinner slices vs. radiation dose 權(quán)衡：薄層 ? Increased use of CT warrants increased attention to radiation dose 良好的 CT應(yīng)用需要提升對(duì)輻射劑量的關(guān)注 Why is MultiSlice dose dependent on total slice width (detector configuration)? 為何多層 CT的劑量取決于檢測(cè)器配置結(jié)構(gòu)？ ? The radiation dose profiles are larger than active detector width 輻射劑量分布大于檢測(cè)器寬度 ? Required in MultiSlice geometry to keep the penumbra off of the active detectors 就幾何形狀而言，半影區(qū)要避開檢測(cè)器 ? Size of penumbral region relatively constant 半影區(qū)的尺寸要相對(duì)恒定 ? Different percentage ―inefficiency‖ for different total scan width 對(duì)不同的掃描厚度具有不同的無(wú)效百分比 Good imaging, good physics ... 好的成像，好的物理特性 … ? Use CTDI, CTDIvol and DLP to help optimize procedures (ALARA) 運(yùn)用 CTDI， CTDIvol和 DLP幫助優(yōu)化操作程序 ? low dose (increased image noise) does not mean poor image quality 低劑量并不意味著損失影像質(zhì)量 ? noise level should be appropriate for the specific diagnostic task not just to get ―pretty‖ pictures 對(duì)于特殊的診斷任務(wù)，噪聲應(yīng)控制在適當(dāng)?shù)乃?—不只是為得到好的畫面 ? narrow slice widths (narrow beam width) should be appropriate for the specific diagnostic task 對(duì)于某些診斷，縮窄層厚是必要的 Dose Conclusions 結(jié)論 ? MultiSlice (MS) systems have similar dose characteristics 多層 CT具有相同的劑量 ? MS dose is primarily determined by the prospective choice of detector configuration 其劑量主要取決于檢測(cè)器配置結(jié)構(gòu)的選擇 ? dose variations among detector configurations were greater than the variations among manufacturers 劑量變化更多的來(lái)源于檢測(cè)器而不是制造商 ? MS CT protocols should be carefully optimized 多層 CT應(yīng)用方案應(yīng)進(jìn)行仔細(xì)的優(yōu)化 ? Thinner slices require narrower beam collimation, which currently leads to higher doses 較薄的層厚需要窄光束進(jìn)行瞄準(zhǔn)，這就加大了劑量 ? Thinner slices also require ? mAs to match noise 就噪聲而言，較薄的層厚也要求 mAs值增高 Summary 總述 ? ―What‘s the dose?‖ is not a simple question 劑量不是一個(gè)簡(jiǎn)單問(wèn)題 ? Know, understand, amp。 Film Printer Evaluation 監(jiān)視器和打印機(jī)評(píng)估 ? Monthly 每月 ? Table Motion and Alignment Lights 床位移和光定位 ? Quarterly 每季 ? Weekly if used for therapy planning 對(duì)于治療方案，可每周進(jìn)行 ? Full Physics Evaluation 全部評(píng)估 ? Annually 每年 ? Following major service 大修后 Essential QC Activities 基本質(zhì)控 ? Determine doses from scanner 確定掃描劑量 ? Working with physician colleagues determine appropriate imaging protocols 與臨床人員協(xié)調(diào)確定適當(dāng)?shù)墓ぷ鞣桨? ? Insure that water has a appropriate CT number 確定水測(cè)試時(shí)獲得適當(dāng)?shù)?CT值 ? Accurate 精度 ? No artifacts 無(wú)偽影 ? Uniform 均一 ? Appropriate noise 噪聲適當(dāng) Essential QC Activities 基本質(zhì)控 ? Insure that the monitors and film printers work correctly 確認(rèn)監(jiān)視器和底片打印機(jī)工作正常 ? Insure that positioning lights and table motion are correct 確認(rèn)定位光和掃描床定位正確 ? Determine doses from scanner 確定掃描劑量 ? CT Dose Fundamentals 基本原則 ? CT Dose Terminology 術(shù)語(yǔ) ? CT Dose Variations – Equipment 劑量變化 —設(shè)備 ? CT Dose Variations – Exams 劑量變化 —測(cè)試 ? CT Dose Optimization 劑量?jī)?yōu)化 CT Dose Evaluation CT計(jì)量評(píng)估 X Z Y CT Coordinates CT 坐
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