本篇主要是以劑量積木的觀念去執行具有鐘垂形狀病灶之鼻咽癌患者的電腦治療計劃，並儘量讓劑量集中在病灶區域，且讓周邊的正常組織和危急器官的劑量降至最低的做法之研究。我們以劑量積木的觀念執行鼻咽癌患者的電腦治療計劃並計算三度空間的劑量分佈。要能夠以劑量積木的觀念執行治療計劃，主要有4項要件相對配合：(1)在以閃掉危急器爲大前提下對病灶做最大範圍的照射；(2)必須能夠對任一照野做劑量的囑咐(prescribe dose)；(3)而在做劑量總合的分析時又能只對某一點做規一化(normalization)；(4)靠沒有散射的照野中心垂面做劑量的堆砌。在劑量積木的方法裹，至少採用5個非共平面的照野；(1)右側頭頂方向由上往下之斜照野(right superior anterior oblique, RSAO)；(2)左側頭頂方向由上往下之斜照野(left superior anterior oblique, LSAO)；(3)右側由上往下之斜照野(right anterior oblique, RAO)；(4)左側由上往下之斜照野(left anterior oblique, LAO)；(5)由頭頂往腳底之斜照野(superior inferior vertex, SIV)。照野的數目和照野的形狀會因腫瘤生長的大小和位置有所修正，但基本上這5個照野已經足夠達到均勻之劑量分佈。不同照野的交接面是以不具散射性的中心軸切面相鄰接而危急器官是以灌製鉛屏蔽的方法避掉輻射線對它的傷害。機器的機械性旋轉中心點之準確性和小照野的劑量可信性也同時以底片和以不同的實驗設計進行測量。使用的設備是Varian 2100C的15 MV的光子射束。以劑量積木的觀念完成的治療計劃之劑量分佈是：至少88%可完全包住腫瘤，而最大劑量約在118%左右。而50%體積的耳下腺約接受總劑量的10~15%；延腦的50%的體積約接受20%的劑量，脊髓大概只接受到5%的散射劑量。以劑量積木的觀念取執行具有鐘垂形狀的鼻咽癌患者之電腦治療計劃，可比傳統的共平面之方法有突破陸的成效；尤其可減輕患者因兩側耳下腺接受大劑量照射後所形成的嚴重口水缺少之症狀。此種方法同時和劑量調變法(IMRT)的結果做比較。

A dose bricks concept has been used for nasopharyngeal carcinoma treatment plan, especially for bell shape lesion cases, The goal of dose bricks concept in treatment planning is to reduce the dose to healthy tissue and sensitive structures around uniformly irradiated target volume. Dose brick concept treatment planning for nasopharyngeal carcinoma with bell shape lesion was done using a commercially available 3 dimensional planning algorithm based on CC Convolution. The dose bricks concept includes four pivotal points: 1) Critical organs sparing should be token to the premier place and the lesion being irradiated by radiation to the utmost. 2) is capable to prescribe dose individually to each field. 3) and normalized to an interested point while summering total dose which were contributed by each individual field. 4) using non-divergent central axial plane to create dose bricks At least five non-corplanner fields were used to approach the dose bricks concept treatment plan: a) Right Superior Anterior Oblique (RSAO). b) Left Superior Anterior Oblique (LSAO). c) Right Anterior Oblique (RAO). d) Left Anterior Oblique (LAO). e) Superior Inferior Vertex (SW). Field numbers and geometry should be modified according to the lesion shape and size case by case. Non-divergence collimator central axis planes were used to create each two different abutting fields while normal organs were blocked by cerrobend alloy in this technique. Mechanical isocenter and small field dose verification were checked by films in different set up design. Dose delivery has been carried out on a Variaa 2100c with 15 MV photon beams, The resulting 88% isodose curves encompassed the GTV, while maximum dose was about 118%. Approximately 50% volume of parotid glands obtained 10-15% of total dose and 50% volume of brain stem obtained less than 20 % of total dose, Spinal cord receive only 5% from the scatter dose, Dose bricks concept in nasopharyngeal carcinoma with a bell shape lesion treatment planning leads to a remarkable critical organs sparing effects especially in parotid glands in minimizing xerostomia compared to that of IMRT results,