ct的質(zhì)量控制ppt課件(2)(完整版)
【正文】 CTDI測(cè)量 ? In phantoms 在模體中 ? Polymethyl methacrylate (acrylic) 丙烯酸 ? 32 cm diameter, ? 16 cm length (body) 頭部模體 ? 16 cm diameter, ? 14 cm length (head) 體部模體 ? At least five 1 cm holes for exposure measurements throughout FOV 至少五個(gè) 1cm測(cè)試空，暴露于全部視場(chǎng)中 ? In air 在空氣中 ? at isocenter (center of rotation) 等量點(diǎn) CTDI Phantoms CTDI模體 Typical FOV dose distributions (%) 典型視場(chǎng)劑量分布 (%) 100 100 100 100 50 Body 32 cm 100 100 100 100 100 Head 16 cm CTDIW = 83 CTDIW = 100 CTDIW CTDIW Weighted average of center and periphery doses 中心和外圍劑量的加權(quán)平均 = 2/3 CTDI100 (edge) + 1/3 CTDI100 (center) Real World …. 現(xiàn)實(shí)情況 … ? Radiation distribution crosses the imaged volume 輻射跨越成像區(qū)域 5 mm 0 + 5 mm Peak dose “Tails” of dose distribution 劑量分布尾跡 Real World …. 現(xiàn)實(shí)情況 … ? Radiation distribution crosses the imaged volume 輻射跨越成像區(qū)域 5 mm 0 + 5 mm A x ial Po s iti on (m m)Exposure (mR)0200400600800100012001400 8 0 6 0 4 0 2 0 0 20 40 60 80S i n g l e s c a n p r o f i l e M u l t i p l e s c a n p r o f i l e : 3 m m x 3 m m , 4 0 s c a n s P o s i t i o n i n s c a n p l a n e = 6 : 0 0 MSAD Multiple Scan Average Dose 多掃描平均計(jì)量 ? MSAD is the average dose over the central scan of a multiple scan exam MSAD是多掃描檢測(cè)時(shí)中心掃描的平均劑量 ? Typically 2 4 times higher than peak doseslice 典型情況為層峰劑量的 24倍 ? Dependent on position in the Field of View (FOV) 取決于在視場(chǎng)中的位置 ? Overestimates patient dose at beginning amp。 CT計(jì)量需要嚴(yán)密關(guān)注。T CTDIvol = N Resolution 分辨率 ? Resolution Test Object 受試目標(biāo)分辨率 Commercial Phantoms 商業(yè)模體 ? Variety of phantoms available 可選的模體很多 ? Accreditation program in the . requires use of phantom designed by American College of Radiology (ACR) which measures more than QC Phantoms from manufacturers 在美國(guó)，認(rèn)證過(guò)程中需使用放射協(xié)會(huì)設(shè)計(jì)的模體，而不僅僅是制造商提供的質(zhì)控模體 Costly 昂貴 Doesn‘t work with manufacturer?s software 不能與制造商提供的軟件一起使用 Requires annual physicist evaluation 每年需要評(píng)估 Monitor Display amp。 end of scan volume 高估了病人在掃描開(kāi)始和結(jié)束時(shí)的劑量 ? Measured directly with TLD amp。 。T CTDIvol = CTDIw When I ? NQuality Control for Computed Tomography (CT), CT, 的質(zhì)量控制 Melissa C. Martin, ., DABR Certified Medical Physicist Fellow ACR, ACMP, AAPM NIM China Meeting June 13, 2022 Qualifications and Professional Activities 專業(yè)資質(zhì)和業(yè)務(wù)活動(dòng) American College of Radiology 美國(guó)放射學(xué)會(huì) Commission on Medical Physics 醫(yī)學(xué)物理學(xué)委員會(huì) Chair of Government Relations Committee 政府關(guān)系委員會(huì)主席 Mammography Accreditation Committee 乳腺 X線照相術(shù)認(rèn)證委員會(huì) Image Quality Committee for Digital Imaging 數(shù)字影像質(zhì)量委員會(huì) American Association of Physicists in Medicine (AAPM) 美國(guó)醫(yī)學(xué)物理學(xué)家協(xié)會(huì) Liaison (Advisor) to the Conference of Radiation Control Program Directors 輻射控制計(jì)劃理事會(huì)大會(huì)顧問(wèn) CT Dose and Image Quality CT輻射劑量和影像質(zhì)量 Quality Control and Quality Assurance Procedures and Issues 質(zhì)量控制和質(zhì)量保證步驟 CT and MRI imaging modalities were named as the most important medical advances in the last half of the 20th century CT和 MRI被認(rèn)為是人類二十世紀(jì)下半葉最重要的進(jìn)展 Developments in CT Technology CT技術(shù)的發(fā)展 Early CT detectors and scanner 早期的 CT檢測(cè)和掃描裝置 Modern MultiSlice CT Scanner 現(xiàn)代多層 CT掃描儀 Early CT Image (Siemens) 早期的 CT影像 MultiSlice CT Images (2022) 多層 CT影像 Quality Assurance 質(zhì)量保證 ? There are a variety of artifacts than can occur because of poor adjustment of the scanner 由于掃描儀調(diào)節(jié)不到位，產(chǎn)生很多干擾偽影 ? Loss of resolution 分辨率下降 ? Accuracy of CT numbers
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