200831939 九、發明說明： 【發明所屬之技術領域】 本發明係關於一種不純性正子斷層掃描(n〇n-pure positron emission tomography ’ NPET)的影像糸統與方法’ 其可經由彳貞測三個光子(photon)來決定射源位置(source position) 〇 【先前技術】 因為正子發射斷層掃描（positron emission tomography，PET)系統用於腫瘤學(onc〇l〇gy)中偵測癌症廣 大範圍具有高敏感度與特定性，所以此PET系統對用於診 斷研究變得非常受歡迎。在PET系統中，同時偵測 (coincident detection)可以提供投影取樣 sampling)，此投影取樣可被重建以產生斷層掃描影像。ρΕτ 的主要優點是能量化(quantify)體内的新陳代謝活動 (metabolism activity) ° 第一圖為一具有同符電路之傳統pET系統。此ρΕτ 系統使用由正子與電子互相毁滅(annihilati〇n)所產生的一 對光子之同符侧。此祕包括配置成環狀且設置在待測 物周圍之數百個彳貞心。每兩個伽彳器是由同符電路連 接。當在相同時間(<12ns则到兩個光子時，此稱為同符 200831939 事件(coincident event)。此等光子之入射方向所形成之線連 接此兩俯貞測器。經由長時間的掃描後，可以獲得許多同 符事件°射源的整體分佈可以用影像重建伽喉 reconstruction)方法，例如濾波器反投影 backprojection，FBP)和最大可能或然期望值最大化 (maximum likelihood expectation maximization，MLEM)， 來算出。 目月il ’PET系統的空間解析度(Spatialres〇luti〇n)受限於 511keV高之光子能量、互相毁滅光子之非共線性 (n〇n_colinearity)、正子射程(positronrange)，以及偵測器技 術。典型的小動物PET系統提供大約4%之絕對敏感度、 以及大約I·6至l.8mm之固有(intrinsic)解析度(Tsui與 Wang 於 2005 年）。 利用單光子斷層掃描(single photon emission computed tomography ’ SPECT)來做高解析度小動物成像是可能的， 此方式為使用比較小動物PET成本低許多的針孔(pinhole) 準直儀(collimator)。此方式大約可以達成ι_的空間解析 度，並且沒有理論上的限制。此種針孔SPECT需要將笨重 的準直器(heavy collimator)圍繞著待測物，並且在設定的環 境裡，小小的對準不良（misalignment)會產生假影 200831939 (artifact)。請注意為了改善敏感度，可以使用多孔式準直 儀。在這種SPECT裡，由於多孔的重疊投影(overlapping projection)重建時也可能產生假影。 截至目前為止，18FDG(氟-脫氧葡萄糖)是PET研究最 常使用的藥劑。然而，此FDG的吸收主要是由於新陳代謝 過私之葡甸糖的吸收’而並不具器官專一性（organ ( sPeciflc)。甚且，當須要長期觀察時，此18F之短的半衰期 (half-life)會限制它的用途。 近年來，對於不純性正子射源之使用有日益增多之興 趣。此使用不純性正子射源以替代用於PET研究之18f， 由於其較長之半衰期與目標特定性質，在診斷或醫療放射 藥物學裡廣受歡迎(Herzog等人於2002年)。此長的半衰期 ( 有利於發展放射化學的合成(radiochemical synthesis)，並且 允許追蹤緩慢的生化過程。 特別令人感興趣的是38K、52mMn、60Cu、94mTc、以及 124I。這些同位素(isotope)為不純性正子射源。此等與正子 同時發射之高能量加馬(gamma)射線(稱為附屬gamma射 線)可能散射(scatter down)至主要能量窗口 (primary energy window)，造成隨機(random)同符事件。被偵測到的光子與 200831939 並非角度函數’因此不含關於其事件的位置資訊。這會降 低PET的性能表現。此等附屬加馬射線事件是均勻分佈於 整個正弦圖(sinogram)，將造成所重建的影像中之低頻背 景0 在物理醫藥生物期刊第49期5505-28所載“在不純性 正子影像中區塊偵測器PET掃描器之表現…模型與具有 1241之實驗証實”中，Robinson等人(2004)主張：此等不純 射源不適用於3D模型，因為散射及隨機事件等大量增加。 在IEEE跨核子科學第50期50_2之“處理此在PET中第三 gamma射線問題”中，Schueller等人(2003)研究在PET中 第三加馬射線之問題，且下結論為無法從第三加馬射線去 獲得利益。200831939 IX. Description of the Invention: [Technical Field] The present invention relates to an imagery system and method for n〇n-pure positron emission tomography (NPET), which can be tested by three Photon determines the source position 〇 [Prior Art] Because the positron emission tomography (PET) system is used in oncology (onc〇l〇gy) to detect a wide range of cancer Sensitivity and specificity, so this PET system has become very popular for diagnostic research. In PET systems, coincidence detection can provide a projection sample, which can be reconstructed to produce a tomographic image. The main advantage of ρΕτ is to quantify the metabolic activity in the body. The first picture shows a traditional pET system with the same circuit. This ρ Ε τ system uses the same side of a pair of photons produced by the annihilation of electrons and electrons (annihilati〇n). This secret consists of hundreds of hearts arranged in a ring shape and placed around the object to be tested. Every two gamma devices are connected by a homogenous circuit. When at the same time (<12ns to two photons, this is called the coincidence 200831939 event. The line formed by the incident direction of these photons connects the two down detectors. After a long scan After that, many of the same-symbol events can be obtained. The overall distribution of the source can be reconstructed by image reconstruction, such as filter backprojection, FBP, and maximum likelihood expectation maximization (MLEM). To calculate. The spatial resolution of the il 'PET system (Spatialres〇luti〇n) is limited by the photon energy of 511 keV, the non-colinearity of each photon (n〇n_colinearity), the positronrange, and the detector technology. . A typical small animal PET system provides an absolute sensitivity of approximately 4% and an intrinsic resolution of approximately 1-6 to 1.8 mm (Tsui and Wang, 2005). It is possible to use high-resolution small animal imaging with single photon emission computed tomography (SPECT), which is a pinhole collimator that uses much lower cost PET than a smaller animal. This approach can achieve a spatial resolution of ι_ with no theoretical limitations. Such pinhole SPECT requires a heavy collimator to surround the object under test, and in a set environment, a small misalignment can produce artifacts 200831939 (artifact). Please note that in order to improve sensitivity, a multi-hole collimator can be used. In this SPECT, artifacts may also occur due to the reconstruction of the porous overlapping projection. To date, 18FDG (fluoro-deoxyglucose) is the most commonly used agent for PET research. However, the absorption of this FDG is mainly due to the absorption of the metabolism of the gluconate, which is not organ-specific (organic (sPeciflc). Moreover, the long half-life of this 18F (half-life) is required when long-term observation is required. It will limit its use. In recent years, there has been an increasing interest in the use of impure positron sources. This uses impure positron sources instead of 18f for PET studies due to its longer half-life and target-specific properties. , popular in diagnostic or medical radiopharmaceutics (Herzog et al. 2002). This long half-life (favors the development of radiochemical synthesis) and allows for the tracking of slow biochemical processes. Interested in 38K, 52mMn, 60Cu, 94mTc, and 124I. These isotopes are impure positron sources. These high-energy gamma rays (called subordinate gamma rays) emitted simultaneously with the positron may scatter. Scatter down to the primary energy window, causing random homomorphic events. The detected photons are not an angle function with 200831939' Does not contain information about the location of the event. This will reduce the performance of the PET. These additional gamma ray events are evenly distributed throughout the sinogram and will cause low frequency background in the reconstructed image. In the 49th, 5505-28, "The performance of the block detector PET scanner in impure positron images... model and experimental verification with 1241", Robinson et al. (2004) argued that these impure sources are not Applicable to 3D models, because of the large increase in scattering and random events, etc. In the IEEE Cross-Nuclear Science 50th 50_2 "Processing this third gamma ray problem in PET", Schueller et al. (2003) studied the third in PET. The problem of the gamma ray, and the conclusion is that it is impossible to obtain benefits from the third gamma ray.
Guerra等人(2〇0〇年)發明一種pET_SPECT系統。此 PET-SPECT系統並非靜態的(stationary)，而是須要將機架 (gantry)旋轉180。以收集所有資料。在美國專利案號 6,303,935所揭示的内容中’ job c.Engdahl等人發明一種 組合式PET/單光子(SPECT或平面式)核子影像系統。如第 二圖所示’此系統使用一對專用（dedicated)pET偵測器 212a-212b與安裝於單一機架21〇上之至少一個專用單光 子偵測器214a-214b°PET偵測器212a_212b僅實施高能量 200831939 PET成像’而此等單光子侧器214&_21北僅實施低能量 單光子成像。此彡統可關時實施pET/S光子影像研究。 此光子彻in也可以移動且安裝於_個別、專㈣單光子 影像機架上。Guerra et al. (2000) invented a pET_SPECT system. This PET-SPECT system is not stationary, but requires the gantry to be rotated 180. To collect all the information. In the context disclosed in U.S. Patent No. 6,303,935, the 'job c. Engdahl et al. invent a combined PET/single photon (SPECT or planar) nuclear imaging system. As shown in the second figure, 'this system uses a pair of dedicated pET detectors 212a-212b and at least one dedicated single photon detector 214a-214b PET detector 212a-212b mounted on a single rack 21A. Only high energy 200831939 PET imaging is implemented' and such single photon side devices 214 & _21 North only implement low energy single photon imaging. This system can be used to perform pET/S photon imaging studies. This photon can also be moved and mounted on a single, dedicated (four) single photon image frame.
Kacperski等人(2〇〇4)也提出一種pET系統。此ρΕτ系 統使用此來自正子毀滅之3γ衰減之同符細。藉由能量與 動量守恒定律，可以判斷射驗置。然而，此射源位置的 準確度大幅取決於此侧器_飾減，並且此^衰減 (attenuation)是稀有事件，其大約小於正規2γ衰減大約兩個 數量級。 不純性正子射源有一些重要的範例。將76Br(溴_76)使 用於分子影像的研究(Beattie等人2〇〇3)。將86γ(紀，使 用於具有9GY-標示之放射藥劑之病人治療中劑量估計 (Buchhdz等人細）。82处(則允許心肌灌流之絕對估計 (Fakhn等人2005)。可以使用正子射源94mTc來改善目前 以99mTc標示之追蹤劑之量化（Barker等人2〇〇1)。將r四丁 使用於比較研究中，其中，診斷與治療放射藥劑以⑵丨或 1311標示（Herzog等人2002)。這些不純性正子射源之長的 半衰期有獅發展放射化學合成，並允許追觀緩慢的生 化過程。此生化過程無法藉由通用之短半衰期的正子射 200831939 源’來作適當地檢驗。 【發明内容】 本發明提供一種稱為不純性正子發射斷層掃描(NPET) 之的衫像系統。其使用附屬(assoCiatecj)加馬射線以協助射 源定位。此NPET系統是根據以下事實：射源位置可以使 用個二階同符電路(triple coincidence circuit)並藉由偵測 三個光子(兩個毀滅光子與一個附屬加馬射線)來決定。 本發明之NPET系統是由兩種型式的偵測系統所構 成’一為PET子系統，另一為SPECT子系統。此兩個子 系統藉由一個三階同符電路而連接。PET子系統偵測毁滅 之光子。SPECT子系統包括至少一個準直器，以偵測附屬 加馬射線，此附屬加馬射線的方向是由此準直器來規範。 此二個光子(兩個毀滅光子與一個附屬加馬射線)是由 其射源晴發射，並且在兩條絲上，此兩條線相交於原 來的發射處。只要此三個光子在相同時間被侧到，則此 射源位置就是位於此附屬加馬射狀人射方向與此毁滅光 子之線的父點上。此幾何交點的定位機制可以淘汰掉散射 與隨機同符事件，也可峨助改善此準直器的解析度。 本發明的優點為，此射源位置可以由偵測到的三個光 10 200831939 子而直接算出，而無須180。之資料擷取或影像重建。這使 得即時成像(real time imaging)成為可能。本發明也提供良 好的時間解析度（temporal resolution)與定量分析 (quantitative analysis)。本發明可以免除散射與隨機事件， 並且可達成南的# 5虎雜 比(signal-tonoise ratio，。 茲配合下列圖示、實施例之詳細說明及申請專利範 圍，將上述及本發明之其他目的與優點詳述於後。 【實施方式】 苐二圖係根據本發明的一個實施例。參考第三圖，此 NPET系統是由兩種型式的偵測系統所構成。第一種型式 的伽!J系統稱為PET子系統，而第二種型式的债測系統稱 為SPECT子系統。此兩個子系統藉由一個三階同符電路 303而連接。此pet子糸統同時偵測兩個毀滅光子(511 Kev)。此毀滅光子的方向(稱為毁滅線)是沿著連接同時攔 截此光子之兩個偵測器的響應線(line ofresp〇nse，l〇r)。 此SPECT子系統是一偵測器302a，並具有至少一個準直 器302b，以偵測由準直器302b來規範方向的附屬光子。 在掃描一物體310的期間，將此ΝρΕΤ系統設置在此物體 310的周圍。點射源(p〇ints〇urce)的位置是經由偵測三個光 子而決定。將來自一能量分辨器後的三個光子的信號饋入 11 200831939 此三階同符電路303中。 不失一般性，此PET子系統可以是如同第三圖中所示 之一對平行偵測器(parallel detector)301a-301b，或是一偵測 環(detector ring)，將於稍後說明。準直器3〇2b可以是一或 更多個平行準直器、一或更多個具有多個針孔之準直器、… 等。第三圖中的準直器3〇2b為一平行準直器。此情況下， 偵測到的附屬加馬射線的方向(稱為附屬線)是由此準直器 來決定。此兩個子系統PET子系統與SPECT子系統可以 彼此垂直，如第三圖所示。 要在相同時間可以债測到這三個光子，並且其能量 是正確的，則此射源位置是位於此附屬線之進入方向與此 毀滅線之交點上。此幾何交點的定位機制可以拒絕散射與 隨機同符事件，並且也可以獅改善此準直器的解析度。 此三個光子的能量是非常高的。可以使用高z材料(highz material)像是BG0或ls〇作為偵測器，來增加偵測效率。 分別示於第四A圖與第四B圖中的隨機與散射同符事 件，經常是發生在傳統的PET系統中。這兩個事件的特徵 是，它們的響應線(LOR)不會通過它們的射源。結果，在 三度空間(3七)幾何中，此LOR(AB)與附屬線〇C沒有交 12 200831939 點，因為此附屬加馬射線是來自此射源。當此附屬加馬射 線被偵測狀前發线㈣，此觀法也是真的。本發明 之NPET系、統具有其本身固有的淘汰非真實事件(散射加 上隨機同符)之機制。此幾何分辨器可以用來減少由此毁滅 光子之正子射私與非共線性(non-colinearity)所造成的效 應0 本發明之NPET系統使用一種幾何分辨器來拒絕此非 真實事件。因為在三度2間(3_D)裡直接定位是可能的，此 可以省略費時且放大雜默重建触。#此自崎低雜訊 的事實，就很明顯得知本發明之NPET系統中具有高snr 的優點。 由於此幾何定位機制，空間解析度並不均勻；垂直的 空間解析度是受限於SPECT子系統，而水平的空間解析度 則受制於PET子系統。此空間解析度可以藉由使用不同角 度例如旋轉90。之掃描而變得更均勻且更細緻。此藉由雙 掃描(0。與90。)之兩個影像Ι〇(χ，前ΐ9〇(χ，y)的幾何平均 為一新影像： 取知=4^(x，y)xI9〇(x，y)， 此於弟五圖中說明。 13 200831939 在本發明中’如果兩條線_最小輯小於—臨界 值’則稱此兩條線相交。本發明中，使用此臨界值來控制 系統的雜解析度，並轉其設定為準直器孔的尺寸。本 發明之NPET系統從-單—事件獲得有_源位置的完整 資訊(忽略其有限_量準確度），而非傳統ρΕΤ系統中的 L〇R。此可以看成是是完美的電子式對位(細咖 registration)。此聽決定兩條線她的位置，並且針對每 個事件都可_立計算。因此#新事件出現，即可實施線 上(on-lme)更新。然而，傳統的pET系統必須要等候完整 影像資料登錄後，再藉由相當娜的綠去重建。因此， 本發月之即日成像對於某種研究例如腦功能之診斷有重大 的好處。 在本發明之NPET系統中可以作定量分析。須要針對 衰減與幾何效率做修正。此NPET系統中，修正因素 (correction factor)是與位置相關的。此修正可以經由首先使 用牙透掃目苗’例如藉由斷層掃描(c〇mputed ， CT)而達成，以建構出一衰減係數對應圖（map 〇f attenuation coefflcient)。一旦偵測到一事件並且決定了它的 射源位置，就可以由此衷減圖算出此三個光子的衰減，且 經修正以得到活度分佈(activity distribution)。 14 200831939 傳統PET系統使用能量分辨器(energy discriminator)來 淘汰散射輻射(scattered radiation)。因此，晶體的高能量解 析度是關鍵的因素。在本發明之ΝΡΕΤ系統中，此散射事 件之淘汰是藉由幾何分辨器而達成，故其能量解析度與否 並不如此重要。 在第三圖之實施例中，針孔準直器可以用於SPECT子 系統中’來加強空間解析度。為了增加敏感度，可以使用 多個針孔準直器。第六圖是根據本發明，將多孔準直器6〇1 使用於NPET系統中的一個範例。雖然對於每一偵測到的 光子可能有多個射源位置，然而經由使用此幾何辨識機 制，就可以容易地找出它的真實位置，並且可以輕容解決 由多個針孔所引起的重疊現象。 根據本發明，傳統PET系統可以用於動物NPET系 統。例如一偵測環(detector ring)702，備有由四個部份 701a-701d所形成的圓柱形針孔準直器，如第七圖所示。此 準直器的兩個部份701a與701b(分別屬於PET區域之上部 與下部)是空的，以允許毀滅光子自由通過。此準直器之其 他兩個部份701 c與701 d(分別屬於SPECT區域之右部與左 部)是多個針孔，用來將附屬光子對準，以經由想要的方向 通過。當然，也需要一個三階同符電路（未示於圖中）。為 15 200831939 了在所有方向中獲得均勻解析度，此圓柱形針孔準直器可 以同^掃描和旋轉。在掃描-物體703的期間，此圓柱形 針孔準直器是設置在此物體7G3與彳貞測環702之間。 第一圖之NPET系統的影像方法可以包含以下三個主 要步驟’如第圖所示。第-步驟是三個光子的同 ' 第一步驟802是判斷此三個光子是否來自相同地 點。第二步驟8G3是使耻由穿透掃描所獲得的衰減圖， 來補4貝此二個絲的衰減。第人B圖為—流糊，進一步 說明第八A圖中的影像方法。 參考第八B圖，此PET子系統與spECT子系統同時 備測此三個光子，並且檢查此三個光子是否同符，如步驟 810所不。如果此三個光子並不同符，則將此事件丢棄。如 果此一個光子同符’則進—步彳貞測此毀滅線與附屬線是否 相交’如步驟82〇所示。將兩線不相交的事件也同樣丢棄。 如果兩線相交，交點設定為此事件地關位置，如步 驟830所示。 如先前提及，本發明之npET系統中也可以作定量分 析。為了達成在步驟840中的衰減補償(attenuati〇n compensation)，而提供物體結構資訊，並由穿透掃描建構 200831939 一衰減圖。因此，可以線上(on-line)更新此影像。 在Kacperski等人(2004)所提出的傳統PET系統中， 其使用由光子毀滅所產生3γ衰減之同符偵測。藉由能量與 動里寸f互疋律，可以決疋此射源位置。然而，此射源定位 的準確度大幅取決於偵測器的能量解析度，且此3γ衰減為 稀有事件，其值大約小於正規3γ衰減大約兩個數量級。相 對地，本發明之ΜΈΤ系統中能量解析度不是如此關鍵的 因素，並且附屬加馬射線的發生機率與正子發射的機率幾 乎相同。 由結構的外觀來看，本發明之ΝΡΕΤ系統類似於由 Guerra等人(2000)提出的PET_SPECT系統。其主要的差異 在於·（1)本杳明之NPET系統使用三階同符電路來同時偵 測三個光子；以及(2)本發明之npet系統是靜止的，而 PET-SPECT系統需要18〇。旋轉來收集所有資料。 針孔SPECT有兩個缺點，即_度低與旋轉軌道 (rotationorbit)不精確。此針孔SPECT需要重準直器來圍繞 物體鉍轉，而且微小的不準會造成旋轉中心(⑵扯沉 rotation)的位移，並且產生假影。雖然本發明之仰£丁系 統包含了-種針轉直器，但並減她。這是因為本發 17 200831939 月使用夕個針孔來增加敏感度，並且不須作任何旋轉。 惟’以上所述者，僅為發明之較佳實施例而已，當不 能依此限定本發明實施之範圍〖即大凡一本發明申請專利 範圍所作之均等變化與修飾，皆應仍屬本發明專利涵蓋之 範圍内。 200831939 【圖式簡單說明】 第一圖為一具有同符電路之傳統PET系統。 第二圖為一傳統之組合式PET/單一光子(SPECT或平面式） 核子影像系統。 第三圖係根據本發明的一個實施例。 第四A圖說明形成影像的隨機同符事件。 第四B圖說明形成影像的散射同符事件。 第五圖說明;^艮據本發明，藉由雙掃描兩個影像的幾何平均， 來形成均勻且較細緻之空間解析度。 第六圖是根據本發明，將多孔準直器使用KNPET系統中的 一個範例。 第七圖是根據本發明，應用於動物_丁系統的_個範例。 第八A圖是根據本發明，NpET系統之影像方法的主要步驟。 第八B圖為—流程圖，進—步說明第人A圖中的影像方法。 【主要元件符號說明】 210 " 212a —----- 212b 214a ϊίϊί 測器 ^ 214b ——~— 單光子偵測器 — —---- 19 200831939 301a 平行偵測器 301b 平行偵測器 302a 偵測器 302b 準直器 303 三階同符電路 310 物體 601 多孔準直器 701a 屬於PET區域之上部 701b 屬於PET區域之下部 701c 屬於SPECT區域之左部 701d 屬於SPECT區域之右部 702 偵測環 703 物體 801 三個光子的同符偵測 802 判斷此三個光子是否來自相同地點 803 使用此由穿透掃描所獲得的衰減圖，來補償此三 個光子的衰減 810 檢查此三個光子是否同符 820 偵測此毁滅線與附屬線是否相交 830 將交點設定為此事件地點的位置 840 衰減補償 20Kacperski et al. (2〇〇4) also proposed a pET system. This ρΕτ system uses this same symmetry of the 3γ attenuation from positron destruction. The energy test can be judged by the law of conservation of energy and momentum. However, the accuracy of this source location is highly dependent on this side- ing reduction, and this attenuation is a rare event that is approximately two orders of magnitude less than the normal 2 gamma attenuation. Impure positron sources have some important examples. 76Br (bromo-76) was used for molecular imaging studies (Beattie et al. 2, 3). 86 gamma, used in the treatment of patients with 9GY-labeled radiopharmaceutical dose estimation (Buchhdz et al.) 82 (then allow absolute estimation of myocardial perfusion (Fakhn et al. 2005). You can use the neutron emitter 94mTc To improve the quantification of the current tracking agent labeled with 99mTc (Barker et al. 2〇〇1). R4 is used in comparative studies, in which diagnostic and therapeutic radiopharmaceuticals are labeled with (2) 丨 or 1311 (Herzog et al. 2002) The long half-life of these impure positron sources is that lions develop radiochemical synthesis and allow for the tracking of slow biochemical processes. This biochemical process cannot be properly tested by the universal short half-life positron shot 200831939 source. SUMMARY OF THE INVENTION The present invention provides a jersey image system called impure positron emission tomography (NPET) that uses an accessory (associate) to assist in locating the source. This NPET system is based on the fact that the source location A second coincidence circuit can be used and determined by detecting three photons (two annihilation photons and one associated gamma ray). The NPET system consists of two types of detection systems: one for the PET subsystem and the other for the SPECT subsystem. The two subsystems are connected by a third-order identical circuit. The PET subsystem detects annihilation The photon. The SPECT subsystem includes at least one collimator to detect the associated gamma ray, and the direction of the tributary gamma ray is specified by the collimator. The two photons (two annihilation photons and one affiliation plus The horse ray is emitted by its source, and on the two wires, the two lines intersect at the original launch. As long as the three photons are sideways at the same time, the source position is located here. The direction of the human shooting is the parent point of the line that destroys the photon. The positioning mechanism of the geometric intersection can eliminate the scattering and random homomorphic events, and can also help improve the resolution of the collimator. The advantage is that the position of the source can be directly calculated from the detected three lights 10 200831939 without the need for data capture or image reconstruction. This makes real time imaging possible. Provide good Good temporal resolution and quantitative analysis. The present invention can eliminate scattering and random events, and can achieve the South's #5-signal-like ratio (signal-tonoise ratio). The above and other objects and advantages of the present invention will be described in detail below. [Embodiment] The second embodiment is in accordance with an embodiment of the present invention. Referring to the third figure, the NPET system is Two types of detection systems are constructed. The first type of gamma system is called the PET subsystem, and the second type of debt measurement system is called the SPECT subsystem. The two subsystems are connected by a third order homomorph circuit 303. This pet sub-system simultaneously detects two annihilation photons (511 Kev). The direction in which the photon is destroyed (called the destruction line) is the line of response (line ofresp〇nse, l〇r) of the two detectors that intercept the photon at the same time. The SPECT subsystem is a detector 302a and has at least one collimator 302b to detect ancillary photons that are normalized by the collimator 302b. The ΝρΕΤ system is placed around the object 310 during scanning of an object 310. The position of the spot source (p〇ints〇urce) is determined by detecting three photons. The signals from the three photons after an energy classifier are fed into the third-order homomorphic circuit 303 of 200831939. Without loss of generality, the PET subsystem can be a parallel detector 301a-301b, or a detector ring, as shown in the third figure, as will be described later. The collimator 3〇2b may be one or more parallel collimators, one or more collimators having a plurality of pinholes, etc. The collimator 3〇2b in the third figure is a parallel collimator. In this case, the detected direction of the attached gamma ray (called the spur line) is determined by the collimator. The two subsystems, the PET subsystem and the SPECT subsystem, can be perpendicular to each other, as shown in the third figure. To measure the three photons at the same time and their energy is correct, the source location is at the intersection of the entry direction of the satellite and the destruction line. The positioning mechanism of this geometric intersection can reject scattering and random homomorphic events, and can also improve the resolution of this collimator. The energy of these three photons is very high. High z material such as BG0 or ls can be used as a detector to increase detection efficiency. Random and scattering homograph events, shown in Figures 4A and 4B, respectively, often occur in conventional PET systems. The characteristic of these two events is that their response lines (LOR) do not pass through their source. As a result, in the three-dimensional space (3-7) geometry, this LOR(AB) does not intersect with the auxiliary line 〇C 12 200831939 because this auxiliary gamma ray is from this source. This view is also true when the attached gamma ray is detected in front of the line (4). The NPET system of the present invention has its own inherent mechanism for eliminating non-real events (scattering plus random symbols). This geometrical discriminator can be used to reduce the effects of positive and non-colinearity of the photon that is destroyed by the photon. The NPET system of the present invention uses a geometrical discriminator to reject this non-real event. Since direct positioning is possible in three degrees (3_D), this can omit time-consuming and amplified silent reconstruction. #本自崎低杂讯 The fact that it is obvious that the NPET system of the present invention has the advantage of high snr. Due to this geometric positioning mechanism, the spatial resolution is not uniform; vertical spatial resolution is limited by the SPECT subsystem, while horizontal spatial resolution is subject to the PET subsystem. This spatial resolution can be rotated by using different angles such as 90. The scan becomes more uniform and more detailed. This is achieved by two scans (0. and 90.) of the two images (χ, the geometric mean of the front ΐ9〇(χ, y) is a new image: 知知=4^(x,y)xI9〇( x, y), which is illustrated in Figure 5. 13 200831939 In the present invention, 'if two lines _ minimum series are smaller than - critical value', the two lines are said to intersect. In the present invention, this threshold value is used to control The heterogeneity of the system is set to the size of the collimator aperture. The NPET system of the present invention obtains complete information on the source location from the -single event (ignoring its finite_quantity accuracy) rather than the traditional ρΕΤ L〇R in the system. This can be seen as a perfect electronic registration (fine coffee registration). This listens to determine the position of her two lines, and can calculate for each event. Therefore #新事件On-line (on-lme) updates can be implemented. However, traditional pET systems must wait for the complete image data to be logged in, and then reconstruct it with a fairly green color. Therefore, this month's instant imaging is for some kind of research. For example, the diagnosis of brain function has significant benefits. It can be used for quantitative determination in the NPET system of the present invention. Correction is required for attenuation and geometric efficiency. In this NPET system, the correction factor is position-dependent. This correction can be performed by first using a toothpick sweep, for example by tomography (c〇mputed, CT). And to achieve a map of attenuation coefficient (map 〇f attenuation coefflcient). Once an event is detected and its source position is determined, the attenuation of the three photons can be calculated from the subtraction map. It has been modified to obtain an activity distribution. 14 200831939 Conventional PET systems use an energy discriminator to eliminate scattered radiation. Therefore, the high energy resolution of the crystal is a key factor. In the invention system, the elimination of this scattering event is achieved by a geometrical discriminator, so the energy resolution is not so important. In the third embodiment, the pinhole collimator can be used for SPECT. In the subsystem to enhance the spatial resolution. In order to increase the sensitivity, a plurality of pinhole collimators can be used. The sixth figure is in accordance with the present invention. An example of using the porous collimator 6〇1 in an NPET system. Although there may be multiple source locations for each detected photon, it is easy to find it by using this geometric identification mechanism. The true position and the overlap caused by multiple pinholes can be easily solved. According to the present invention, a conventional PET system can be used in an animal NPET system, such as a detector ring 702, which is provided with four The cylindrical pinhole collimator formed by the portions 701a-701d is as shown in the seventh figure. The two portions 701a and 701b of the collimator (belonging to the upper and lower portions of the PET region, respectively) are empty to allow the destruction of photons to pass freely. The other two portions 701 c and 701 d of the collimator (to the right and left of the SPECT region, respectively) are a plurality of pinholes for aligning the attached photons to pass through the desired direction. Of course, a third-order identical circuit is also needed (not shown). For 15 200831939 to achieve uniform resolution in all directions, this cylindrical pinhole collimator can be scanned and rotated. This cylindrical pinhole collimator is disposed between the object 7G3 and the test ring 702 during the scanning-object 703. The image method of the NPET system of the first figure can include the following three main steps as shown in the figure. The first step is the same as the three photons. The first step 802 is to determine whether the three photons are from the same location. The second step 8G3 is to attenuate the attenuation obtained by the penetration scan to compensate for the attenuation of the two filaments. The first person B picture is - flow, further illustrating the image method in the eighth picture A. Referring to Figure 8B, the PET subsystem and the spECT subsystem simultaneously prepare the three photons, and check whether the three photons are the same, as in step 810. If the three photons are different, the event is discarded. If the one photon is the same as the ', then step to determine if the destruction line intersects the satellite line' as shown in step 82. Events that disjoint two lines are also discarded. If the two lines intersect, the intersection is set to the off position of the event, as shown in step 830. As mentioned previously, quantitative analysis can also be performed in the npET system of the present invention. In order to achieve the attenuation compensation in step 840, the object structure information is provided, and an attenuation map is constructed by the penetration scan 200831939. Therefore, this image can be updated on-line. In the conventional PET system proposed by Kacperski et al. (2004), it uses the same-symbol detection of 3γ attenuation produced by photon destruction. This source position can be determined by the mutual law of energy and motion. However, the accuracy of this source localization is highly dependent on the detector's energy resolution, and this 3 gamma decay is a rare event with a value that is approximately two orders of magnitude less than the normal 3 gamma attenuation. In contrast, the energy resolution in the helium system of the present invention is not such a critical factor, and the probability of occurrence of the associated gamma ray is almost the same as the probability of positron emission. The sputum system of the present invention is similar to the PET SPECT system proposed by Guerra et al. (2000) in terms of the appearance of the structure. The main difference is that (1) the NPET system of the present invention uses a third-order homomorphic circuit to simultaneously detect three photons; and (2) the npet system of the present invention is stationary, while the PET-SPECT system requires 18 〇. Rotate to collect all the data. Pinhole SPECT has two disadvantages, namely, low _degree and inaccurate rotationorbit. This pinhole SPECT requires a heavy collimator to wrap around the object, and a slight inaccuracy can cause displacement of the center of rotation ((2) torsion rotation) and artifacts. Although the invention of the present invention includes a needle-type straightener, it is reduced. This is because the hair pinhole is used to increase the sensitivity and does not require any rotation. However, the above description is only a preferred embodiment of the invention, and the scope of the invention may not be limited thereto, that is, the equivalent variation and modification of a patent application scope of the invention shall remain the patent of the invention. Within the scope of coverage. 200831939 [Simple description of the diagram] The first picture shows a traditional PET system with the same circuit. The second picture shows a conventional combined PET/single photon (SPECT or planar) nuclear image system. The third figure is an embodiment in accordance with the present invention. Figure 4A illustrates a random homograph event that forms an image. Figure 4B illustrates the scattering homolog events that form the image. The fifth figure illustrates; according to the present invention, a uniform and finer spatial resolution is formed by double scanning the geometric mean of the two images. The sixth figure is an example of the use of a KNPET system for a porous collimator in accordance with the present invention. The seventh figure is an example of application to an animal system according to the present invention. Figure 8A is the main steps of the image method of the NpET system in accordance with the present invention. The eighth picture B is a flow chart, and the method of the image in the figure A of the first person is explained. [Main component symbol description] 210 " 212a —----- 212b 214a ϊίϊί Detector ^ 214b ——~— Single photon detector — —--- 19 200831939 301a Parallel detector 301b Parallel detector 302a detector 302b collimator 303 third-order homograph circuit 310 object 601 porous collimator 701a belongs to PET region upper portion 701b belongs to PET region lower portion 701c belongs to SPECT region left portion 701d belongs to SPECT region right portion 702 detection Ring 703 Object 801 Three-photon homophone detection 802 Determines whether the three photons are from the same location 803. Use this attenuation map obtained by the penetration scan to compensate for the attenuation of the three photons. 810 Check if the three photons are The same symbol 820 detects whether the destruction line intersects with the auxiliary line 830 sets the intersection point to the position of the event location 840 attenuation compensation 20