Several of the previous chapters have addressed film/screen image receptors (digital image receptors are discussed in a later chapter) and the importance of quality control testing to avoid poor-quality images. However, many other components of diagnostic imaging departments are subject to variability and must have separate quality control protocols established to ensure safe operation and function. One such component is the equipment used to convert electrical energy into electromagnetic energy (X-rays), commonly called the X-ray unit or X-ray machine. Components of the X-ray machine include the X-ray generator, the control or operating console, a highvoltage generator, and the X-ray tube, tube accessories, and patient support assembly. 前几章讨论了电影/屏幕图像接收器（数字图像接收器将在后面的章节中讨论）以及质量控制测试的重要性，以避免低质量图像。然而，诊断成像部门的许多其他组件也会受到变动的影响，必须建立单独的质量控制协议，以确保安全操作和功能。其中一个组件是将电能转换为电磁能（X 射线）的设备，通常称为 X 射线机或 X 射线装置。X 射线机的组件包括 X 射线发生器、控制或操作控制台、高压发生器以及 X 射线管、管配件和病人支撑组件。
X-RAY GENERATOR X 射线发生器
The X-ray generator is the largest component of the radiographic unit. It contains the high-voltage transformers, rectifiers, timing circuitry, and milliampere-second (mAs) and kilovolt (peak) (kVp) selectors. Single-phase, three-phase, and high-frequency X-ray generators are available. X 射线发生器是放射摄影设备中最大的组成部分。它包含高压变压器、整流器、定时电路以及毫安秒（mAs）和千伏（峰值）（kVp）选择器。可提供单相、三相和高频 X 射线发生器。
Single-Phase Generator 单相发电机
A single source of alternating current is used to power the generator in a single-phase ( 1Phi1 \Phi ) (Greek letter phi) generator. A representation of single-phase alternating current is shown in Fig. 5.1. 单相（ 1Phi1 \Phi ）（希腊字母 phi）发电机中使用单一的交流电源为发电机供电。单相交流电的表示如图 5.1 所示。
The graph in Fig. 5.1 plots the voltage on the yy-axis versus time on the x -axis. The peaks in the graph represent the flow of electricity changing direction throughout the circuit. Voltage values range from 0 V to a peak value (hence the term kilovolts [peak]) and back to 0 V . The two types of single-phase generators used in diagnostic radiography are half-wave rectified and full-wave rectified. 图 5.1 中的图表绘制了 yy 轴上的电压与 x 轴上的时间的关系。图中的峰值代表电流在电路中改变方向。电压值范围从 0 伏到峰值（因此称为千伏[峰]）再回到 0 伏。在诊断放射摄影中使用的两种单相发电机是半波整流和全波整流。
Half-Wave Rectified 半波整流
Before going any further, we must first define the term rectification as it is used in describing different types of X-ray generators. Rectification is the process of changing alternating 在进一步讨论之前，我们必须首先定义在描述不同类型的 X 射线发生器时使用的术语“整流”。整流是将交流电转换为直流电的过程。
Fig. 5.1 Voltage waveform graph of a single-phase alternating current. 图 5.1 单相交流电的电压波形图。
current into a pulsating direct current. All types of X-ray machines must carry out rectification because the transformers require alternating current to properly function and X-ray tubes will only function properly with direct current. 将交流电转换为脉动直流电。所有类型的 X 射线机必须进行整流，因为变压器需要交流电才能正常工作，而 X 射线管只有在直流电下才能正常工作。
In a half-wave rectified generator (sometimes known as a one-pulse, or self-rectified X-ray generator), one-half the normal alternating current wave is used to power the X-ray tube and the other half is shut off by the addition of one or two rectifiers. This design causes the normal single-phase alternating current waveform graph to appear as shown in Fig. 5.2. 在半波整流发电机（有时称为单脉冲或自整流 X 射线发电机）中，正常交流电波的一半用于为 X 射线管供电，另一半则通过添加一个或两个整流器被关闭。这种设计使得正常的单相交流电波形图呈现如图 5.2 所示。
Because the standard frequency of alternating current in the United States is 60 Hz , or 60 cycles per second (a cycle represents the current flowing in each direction one time), only 60 pulses of electricity per second (or one pulse per cycle) can be used to create X-rays. This means the X-rays are emitted in pulses, or spurts, and therefore a longer amount of time is required to obtain a specific quantity of X-rays. For this reason, half-wave rectified units are generally used in dental X-ray units and some small portable X-ray units. 由于美国的交流电标准频率为 60 赫兹，即每秒 60 个周期（一个周期表示电流在每个方向流动一次），因此每秒只能使用 60 个电流脉冲（或每个周期一个脉冲）来产生 X 射线。这意味着 X 射线是以脉冲或突发的方式发射的，因此需要更长的时间才能获得特定数量的 X 射线。因此，半波整流装置通常用于牙科 X 射线装置和一些小型便携式 X 射线装置。
Full-Wave Rectified 全波整流
Full-wave rectified or two-pulse generators use a combination of four rectifiers to channel all the pulses through the X-ray tube during X-ray production. The resultant waveform through the X-ray tube contains two pulses per cycle or 120 pulses per second. The resulting waveform graph for this type of unit appears in Fig. 5.3. 全波整流或双脉冲发电机使用四个整流器的组合，在 X 射线产生过程中将所有脉冲引导通过 X 射线管。通过 X 射线管的结果波形每个周期包含两个脉冲，或每秒 120 个脉冲。这种类型设备的结果波形图如图 5.3 所示。
Because 120 pulses of electricity per second can be used to create X-rays, twice as many X-rays can be created per mAs as compared with the half-wave unit. This fact allows full-wave rectified units to be used for many conventional radiographic procedures. However, the X-rays are still emitted in pulses (as demonstrated by the number of times the pulses reach 0 V on the waveform graph) and therefore still require some time to achieve a specific quantity of X-rays. The shortest exposure time available for single-phase X-ray generators is 1//120sec1 / 120 \mathrm{sec} ond. For this reason, full-wave rectified units are seldom 因为每秒 120 个脉冲的电流可以用来产生 X 射线，因此每毫安秒（mAs）产生的 X 射线数量是半波单元的两倍。这一事实使得全波整流单元可以用于许多常规放射摄影程序。然而，X 射线仍然是以脉冲形式发射的（如波形图中脉冲达到 0 V 的次数所示），因此仍然需要一些时间来达到特定数量的 X 射线。单相 X 射线发生器可用的最短曝光时间为 1//120sec1 / 120 \mathrm{sec} 毫秒。因此，全波整流单元很少被使用。
Fig. 5.2 Voltage waveform graph of a half-wave rectified, single-phase current. 图 5.2 半波整流单相电流的电压波形图。
Fig. 5.3 Voltage waveform graph of a full-wave rectified single-phase current. 图 5.3 全波整流单相电流的电压波形图。
Fig. 5.4 Voltage waveform graph of a three-phase alternating current. 图 5.4 三相交流电的电压波形图。
found in larger hospitals but may be found in doctors’ offices and small clinics. 在较大的医院中发现，但也可能在医生办公室和小诊所中发现。
Three-Phase Generator 三相发电机
Three-phase (3Ф) X-ray generators are powered by three separate sources of alternating current that are staggered so they are “out of phase” with one another by 120 degrees, or one-third of a cycle. The voltage waveform graph for threephase alternating current appears in Fig. 5.4. 三相（3Ф）X 射线发生器由三个独立的交流电源供电，这些电源的相位错开 120 度，即一个周期的三分之一。三相交流电的电压波形图如图 5.4 所示。
By the time one pulse of current begins to drop toward 0 V , another pulse is heading back up to the maximum value, so the voltage never reaches 0 V and X -rays are produced constantly (eliminating the pulsed effect of single-phase units), which allows exposure time values as low as 1//10001 / 1000 second ( 1 ms ). The X-rays created with three-phase units also have a greater average energy than those of single-phase units because the voltage is near the peak value for a greater percentage of the time during X-ray production (which can lower patient dose compared with single-phase units). The main disadvantages of three-phase equipment are greater capital cost (at least twice as expensive as a single-phase unit) and the size of the unit (because of the additional electronic components required). In general, the advantages outweigh the disadvantages, and the three-phase X-ray generator has been the most common type of unit in major hospitals and medical centers up until the year 2000. The two types of three-phase generators are six-pulse and 12 -pulse generators. 当一个电流脉冲开始下降到 0 伏时，另一个脉冲正朝着最大值上升，因此电压从未达到 0 伏，X 射线持续产生（消除了单相设备的脉冲效应），这使得曝光时间值低至 1//10001 / 1000 秒（1 毫秒）。使用三相设备产生的 X 射线平均能量也高于单相设备，因为在 X 射线产生过程中，电压在更大比例的时间内接近峰值（这可以降低与单相设备相比的患者剂量）。三相设备的主要缺点是资本成本更高（至少是单相设备的两倍）以及设备的体积（由于需要额外的电子元件）。总体而言，优点超过缺点，三相 X 射线发生器在 2000 年之前一直是主要医院和医疗中心最常见的设备类型。三相发生器有两种类型：六脉冲和 12 脉冲发生器。
Three-Phase, Six-Pulse Generators 三相六脉冲发电机
The six-pulse type of three-phase unit uses six rectifiers and one-half the three-phase alternating current pulses. The resulting voltage waveform appears in Fig. 5.5. 六脉冲型三相装置使用六个整流器和一半的三相交流电脉冲。所产生的电压波形如图 5.5 所示。
Fig. 5.5 Voltage waveform graph of a three-phase, six-pulse current. V_("max ")V_{\text {max }}, Peak voltage across the X-ray tube during X-ray production. 图 5.5 三相六脉冲电流的电压波形图。 V_("max ")V_{\text {max }} ，X 射线产生过程中 X 射线管的峰值电压。
Fig. 5.6 Voltage waveform graph of a three-phase, 12-pulse current. V_("max ")V_{\text {max }}, Peak voltage across the X-ray tube during X-ray production. 图 5.6 三相 12 脉冲电流的电压波形图。 V_("max ")V_{\text {max }} ，X 射线产生过程中 X 射线管的峰值电压。
As mentioned previously, one cycle of single-phase alternating current refers to one pulse of electricity traveling each direction one time so that two pulses comprise one cycle. Because 60 cycles occur each second, one cycle requires a time of 1//601 / 60 second. In a three-phase, six-pulse X-ray generator, six pulses of electricity exist during the same cycle or 1//601 / 60-second time interval (instead of two pulses per 1//601 / 60 second in single phase), hence the name three-phase, six-pulse. This means that 360 voltage pulses are now available per second. 如前所述，单相交流电的一个周期指的是电流在每个方向上移动一次的一个脉冲，因此两个脉冲构成一个周期。由于每秒发生 60 个周期，一个周期需要 1//601 / 60 秒。在三相六脉冲 X 射线发生器中，在同一个周期或 1//601 / 60 秒的时间间隔内存在六个电脉冲（而不是单相中的每 1//601 / 60 秒两个脉冲），因此得名三相六脉冲。这意味着每秒现在可用 360 个电压脉冲。
Three-Phase, 12-Pulse Generators 三相 12 脉冲发电机
The three-phase, 12-pulse type of X-ray generator uses 12 rectifiers (four rectifiers per phase) that direct all the three-phase alternating current pulses through the X-ray tube during X-ray production. This action yields 12 pulses of electricity per one-cycle ( 1//601 / 60-second) time interval, for a total of 720 voltage pulses available per second. This unit is more efficient than the three-phase, six-pulse unit but is more expensive in capital cost. The voltage waveform for a three-phase, 12-pulse X-ray generator appears in Fig. 5.6. 三相 12 脉冲型 X 射线发生器使用 12 个整流器（每相四个整流器），在 X 射线产生过程中将所有三相交流电脉冲导入 X 射线管。此操作在一个周期（ 1//601 / 60 秒）时间间隔内产生 12 个电脉冲，每秒可提供 720 个电压脉冲。该装置的效率高于三相六脉冲装置，但资本成本更高。三相 12 脉冲 X 射线发生器的电压波形如图 5.6 所示。
High-Frequency Generator 高频发电机
Developed during the late 1970s, high-frequency X-ray generators were the newest generators available. They are sometimes referred to as medium-frequency generators, depending on the design and manufacturer. These units can be supplied with either a single-phase or three-phase source of alternating current that is first fed into a microprocessor circuit before entering the high-voltage section. This microprocessor changes the frequency of the alternating current from the standard 60 Hz to as much as 100,000Hz100,000 \mathrm{~Hz} in some of the more recent models. It is then rectified and smoothed with capacitors before application across the X-ray tube, which causes the pulses to merge together and results in a voltage waveform such as the one that appears in Fig. 5.7. 在 1970 年代末期开发的高频 X 射线发生器是当时最新的发生器。根据设计和制造商的不同，它们有时被称为中频发生器。这些设备可以使用单相或三相交流电源，首先将其输入微处理器电路，然后再进入高压部分。该微处理器将交流电的频率从标准的 60 Hz 改变为一些较新型号中的高达 100,000Hz100,000 \mathrm{~Hz} 。然后，它经过整流和电容器平滑处理后应用于 X 射线管，这导致脉冲合并在一起，产生如图 5.7 所示的电压波形。
High-frequency generators and three-phase generators produce similar voltage waveforms. However, the capital cost and power requirements for high-frequency units are far less than those for three-phase units. The transformers in 高频发电机和三相发电机产生类似的电压波形。然而，高频设备的资本成本和功率需求远低于三相设备。变压器在
Time 时间
Fig. 5.7 Voltage waveform graph showing the resulting current through the XX-ray tube in a high-frequency XX-ray generator. 图 5.7 显示高频 XX -射线发生器中通过 XX -射线管的电流的电压波形图。
high-frequency units can be smaller because they are much more efficient at higher frequencies (according to Faraday’s Law of Electromagnetism), which accounts for the lower capital cost. The transformers also reduce the space requirement for installation. Because these units yield most of the advantages of a three-phase unit but at a fraction of the cost, they have become the most commonly utilized X-ray systems in hospitals, medical centers, clinics, and doctors’ offices. 高频设备可以更小，因为它们在更高频率下的效率更高（根据法拉第电磁学定律），这也解释了较低的资本成本。这些变压器还减少了安装所需的空间。由于这些设备在成本仅为三相设备的一小部分的情况下，提供了大部分三相设备的优势，因此它们已成为医院、医疗中心、诊所和医生办公室中最常用的 X 射线系统。
Voltage Ripple 电压波动
Voltage ripple is a term used often to distinguish the voltage waveforms of each type of X-ray generator. A voltage ripple is the amount of variation from the peak voltage that occurs during X-ray production. The voltage ripple value is determined by the following equation: 电压波动是一个常用术语，用于区分每种类型的 X 射线发生器的电压波形。电压波动是指在 X 射线产生过程中，峰值电压的变化量。电压波动值由以下方程确定：
%" voltage ripple "=(V_(max)-V_(min))//V_(max)xx100\% \text { voltage ripple }=\left(\mathrm{V}_{\max }-\mathrm{V}_{\min }\right) / \mathrm{V}_{\max } \times 100
V_(max)\mathrm{V}_{\max } is the peak voltage across the X-ray tube during X-ray production, while V_("min ")\mathrm{V}_{\text {min }} is the lowest voltage across the tube during X-ray production. For single-phase units, the voltage ripple is considered to be 100%100 \% because the voltage drops from its peak all the way to 0 V before increasing again, so 100%100 \% of all possible voltages are obtained. For three-phase equipment, the voltage does not decrease all the way to 0 V . One pulse increases as soon as the previous one falls, which yields a voltage ripple of 13%13 \% for a three-phase, six-pulse generator and a ripple of 3.5%3.5 \% for a three-phase, 12-pulse unit. High-frequency generators can create voltage ripple values between 1%1 \% and 15%15 \%, which are comparable with those of three-phase units. V_(max)\mathrm{V}_{\max } 是 X 射线管在 X 射线产生过程中的峰值电压，而 V_("min ")\mathrm{V}_{\text {min }} 是 X 射线产生过程中的最低电压。对于单相设备，电压波动被认为是 100%100 \% ，因为电压从峰值下降到 0 V，然后再上升，因此获得了所有可能电压的 100%100 \% 。对于三相设备，电压不会下降到 0 V。一个脉冲在前一个脉冲下降时立即上升，这导致三相六脉冲发电机的电压波动为 13%13 \% ，而三相 12 脉冲单元的波动为 3.5%3.5 \% 。高频发电机可以产生介于 1%1 \% 和 15%15 \% 之间的电压波动值，这与三相设备的波动值相当。
Power Ratings 功率评级
The power output of an X-ray generator is used to measure the capacity of X-ray production from the individual unit. This value is measured in kilowatts ( kW ) and is called the kilowatt rating. It is usually calculated by determining the maximum combinations of kVp and milliamperes ( mA ) that can be achieved by a particular generator at an exposure time of 100 ms . These two values are then placed into the following equations: X 射线发生器的功率输出用于测量单个设备的 X 射线生产能力。该值以千瓦（kW）为单位，称为千瓦额定值。通常通过确定特定发生器在 100 毫秒曝光时间内可以达到的 kVp 和毫安（mA）的最大组合来计算。然后将这两个值代入以下方程：
The rippling effect of the single-phase alternating current requires that the 0.707 multiplier be added to the equation. 单相交流电的涟漪效应要求在方程中添加 0.707 的乘数。
The greater the power rating of the X-ray generator, the higher the purchase price of the system. X 射线发生器的功率等级越高，系统的购买价格就越高。
CONTROL OR OPERATING CONSOLE 控制或操作控制台
The control or operating console contains all the various controls to operate the X-ray machine (e.g., kVp selector, mAs selector) and various meters to monitor the production of X-rays. Guidelines by the US Food and Drug Administration mandate that diagnostic X-ray machine operating consoles must indicate the conditions of exposure ( kVp,mAs\mathrm{kVp}, \mathrm{mAs} ) and when the X-ray tube is energized. The conditions of exposure usually are indicated by the mAs and kVp selection mechanism (i.e., the mAs or kVp buttons or computer touch pad keys that are pushed). There is also either an analog or a digital milliamp-second meter to indicate the quantity of X-rays produced by the X-ray unit. These meters also are used to indicate energized X-ray tubes and to detect lights or audible signals. Characteristics for the control booth area, which houses the operating console of a radiographic X-ray unit, include the following: 控制或操作控制台包含操作 X 射线机的各种控制装置（例如，kVp 选择器、mAs 选择器）和用于监测 X 射线产生的各种仪表。美国食品药品监督管理局的指南规定，诊断 X 射线机的操作控制台必须指示曝光条件（ kVp,mAs\mathrm{kVp}, \mathrm{mAs} ）以及 X 射线管何时通电。曝光条件通常通过 mAs 和 kVp 选择机制指示（即，按下的 mAs 或 kVp 按钮或计算机触摸板键）。还有一个模拟或数字毫安秒表，用于指示 X 射线设备产生的 X 射线数量。这些仪表还用于指示通电的 X 射线管，并检测灯光或可听信号。控制室区域的特征，包括放射性 X 射线设备的操作控制台，包含以下内容：
The floor of the control booth must be 7.5ft^(2)7.5 \mathrm{ft}^{2} or larger. 控制室的地板必须为 7.5ft^(2)7.5 \mathrm{ft}^{2} 或更大。
The exposure switch should be fixed within the booth at a position at least 30 inches from any open edge of the booth wall and should be closest to the examining table. 曝光开关应固定在展位内，位置距离展位墙的任何开放边缘至少 30 英寸，并应靠近检查台。
X-ray photons must scatter at least twice before they can enter any opening in the control booth. Each time an X-ray photon scatters, its intensity from the scattering object is 1//10001 / 1000 of the original intensity at a distance of 1 m . X 射线光子必须至少散射两次才能进入控制室的任何开口。每当 X 射线光子散射时，从散射物体发出的强度在 1 米的距离上是原始强度的 1//10001 / 1000 。
The control booth window must have the same shielding requirements as the walls (usually a 1.5-mm1.5-\mathrm{mm} lead equivalent), be at least 1ft^(2)1 \mathrm{ft}^{2} in size, and be mounted at least 5 feet above the floor. There should be no obstructions blocking the view of the patient table. 控制室窗口必须具有与墙壁相同的屏蔽要求（通常为 1.5-mm1.5-\mathrm{mm} 铅当量），尺寸至少为 1ft^(2)1 \mathrm{ft}^{2} ，并且安装高度至少为 5 英尺。视线应无障碍物阻挡患者台。
The wall of the control booth, facing the radiographic examination table, must be at least 7 feet high and fixed to the floor. 控制室面向放射检查台的墙壁必须至少高 7 英尺，并固定在地面上。
Any door on the control booth that is an entrance to the examination room should be interlocked with the control panel so that an exposure cannot be made unless the door is closed. 控制室内任何通往考试室的门应与控制面板联锁，以确保在门关闭之前无法进行曝光。
HIGH-VOLTAGE GENERATOR 高压发电机
The high-voltage generator of the radiographic unit is responsible for converting the relatively low-voltage values supplied by the power companies (usually 220-440V220-440 \mathrm{~V} ) to the kilovolt levels necessary for the production of diagnostic radiographs. Included in this generator is a high-tension transformer, which is a shell-type step-up transformer that increases the voltage level selected using an autotransformer to the kilovolts selected on the control console. Also included in the high-voltage generator is a filament (step-down) transformer that feeds a stepped-down voltage level to the filament of the X-ray tube. This area also may contain rectifiers that convert the alternating current of the incoming power supply to a pulsating direct current that is fed to the X-ray tube for X-ray production. The number of rectifiers ranges from 4 to 12 depending on the type of X-ray generator and are usually solid state in nature. The high-voltage generator is normally 放射线摄影装置的高压发电机负责将电力公司提供的相对低电压值（通常为 220-440V220-440 \mathrm{~V} ）转换为生产诊断放射线照片所需的千伏级电压。该发电机中包含一个高压变压器，这是一个壳式升压变压器，通过自耦变压器将所选电压水平提升至控制台上选择的千伏级电压。此外，高压发电机中还包含一个灯丝（降压）变压器，为 X 射线管的灯丝提供降压电压。该区域还可能包含整流器，将输入电源的交流电转换为脉动直流电，以供 X 射线管进行 X 射线生产。整流器的数量根据 X 射线发电机的类型从 4 个到 12 个不等，通常为固态。高压发电机通常
housed in a metal box that may be found in the X-ray room or in a nearby area, such as the control booth. High-voltage cables (one going to the cathode of the X-ray tube and another to the anode) connect the high-voltage generator to the X -ray tube. 放置在金属箱中，该箱可能位于 X 射线室或附近区域，例如控制室。高压电缆（一个连接到 X 射线管的阴极，另一个连接到阳极）将高压发生器连接到 X 射线管。
X-RAY TUBE, TUBE ACCESSORIES, AND PATIENT SUPPORT ASSEMBLY X 射线管、管道附件和病人支撑组件
The third main part of any radiographic X-ray unit is a combination of the X-ray tube, X-ray tube support mechanism, patient support assembly (i.e., X-ray examination table), and X-ray tube accessories such as the collimator and added filtration. Most radiographic X-ray tubes are rotating anode X-ray tubes that can withstand greater kVp and mAs combinations than the stationary anode X -ray tubes used in dental offices and in small portable X-ray machines. The X-ray tube must be equipped with a metal housing to prevent leakage of radiation. This housing must confine the leakage amount to less than 100 mR per hour ( 1 mGy per hour air kerma) when measured at a distance of 1 m away from the housing. The X-ray tube must also be equipped with a variable-aperture collimator to control the size of the X-ray field (discussed in detail later in this chapter). The X-ray tube support mechanism that holds the X-ray tube in position over the bucky device must have the following characteristics (the bucky device contains the image receptor and is taught to X-ray students on the first day of the program): 任何放射线 X 光机的第三个主要部分是 X 光管、X 光管支撑机制、患者支撑组件（即 X 光检查台）以及 X 光管配件，如准直器和附加过滤器的组合。大多数放射线 X 光管是旋转阳极 X 光管，能够承受比牙科办公室和小型便携式 X 光机中使用的固定阳极 X 光管更高的 kVp 和 mAs 组合。X 光管必须配备金属外壳，以防止辐射泄漏。该外壳在距离外壳 1 米处测量时，泄漏量必须限制在每小时少于 100 mR（每小时 1 mGy 空气剂量）。X 光管还必须配备可变孔径准直器，以控制 X 光场的大小（在本章后面将详细讨论）。支撑 X 光管在 Bucky 装置上方位置的 X 光管支撑机制必须具备以下特征（Bucky 装置包含图像接收器，并在课程的第一天教授给 X 光学生）：
The support mechanism must be strong because the X -ray tube, insulating coil, collimator, and metal housing are heavy. 支撑机制必须强大，因为 X 射线管、绝缘线圈、准直器和金属外壳都很重。
The support mechanism should be counterbalanced to help offset the weight of the X-ray tube and accessory devices. This design makes the assembly more stable and allows it to be moved more easily during patient positioning. 支撑机制应进行平衡，以帮助抵消 X 射线管和附属设备的重量。该设计使组件更加稳定，并在患者定位时更易于移动。
Immobilization locks must be incorporated into the support mechanism to hold the X-ray tube in position. 必须将固定锁纳入支撑机制，以保持 X 射线管的位置。
In relation to the image receptor, the X -ray tube position must be indicated clearly (source-to-image distance [SID] indicator) and must be accurate to within 2%2 \% of the SID. In addition, if a radiographic examination table is present (as opposed to an upright bucky or chest unit), the maximum tabletop thickness over the bucky assembly is 1 mm of aluminum equivalent to prevent the tabletop material from absorbing excessive amounts of radiation before reaching the image receptor (which would, therefore increase the patient dose). 关于影像接收器，X 射线管的位置必须清晰指示（源到影像距离[SID]指示器），并且必须在 SID 的 2%2 \% 范围内准确。此外，如果存在放射线检查台（与直立式 Bucky 或胸部设备相对），则 Bucky 组件上方的最大台面厚度为 1 毫米铝当量，以防止台面材料在到达影像接收器之前吸收过量的辐射（这将因此增加患者剂量）。
QUALITY CONTROL PROGRAM FOR RADIOGRAPHIC UNITS 放射线设备质量控制程序
When the X-ray equipment has been installed successfully and has passed all acceptance tests, it needs to be monitored periodically to ensure it continues to perform according to the manufacturer’s specifications. This periodic testing is the quality control testing of the equipment. The main goal of this quality control program is to ensure consistent, high-quality diagnostic images, minimize radiation exposure to both 当 X 射线设备成功安装并通过所有验收测试后，需要定期进行监测，以确保其继续按照制造商的规格进行操作。这种定期测试是设备的质量控制测试。该质量控制程序的主要目标是确保一致的高质量诊断图像，最小化对患者和操作人员的辐射暴露。
patient and department staff, and help in cost effectiveness by reducing downtime and waste. The three parts of a quality control program for radiographic equipment are visual inspection, environmental inspection, and performance testing. These tests should be performed upon acceptance of new equipment (or after a major repair of existing equipment) and then at least annually. Any items that are found to not meet manufacturer’s specifications will need to be corrected or repaired. Most states and accrediting agencies require that all records of corrections or repairs be maintained for inspection. In addition, records of quality control testing should also be maintained in either written form or in a computerized database. 患者和部门工作人员，并通过减少停机时间和浪费来帮助提高成本效益。放射设备质量控制程序的三个部分是视觉检查、环境检查和性能测试。这些测试应在新设备接受时（或在现有设备进行重大维修后）进行，然后至少每年进行一次。任何未达到制造商规格的项目都需要进行修正或维修。大多数州和认证机构要求维护所有修正或维修记录以供检查。此外，质量控制测试的记录也应以书面形式或计算机数据库的形式进行保存。
Visual Inspection 目视检查
Visual inspection includes checking the main components of the equipment to ensure that there are no hazardous, inoperative, out-of-alignment, or improperly operating items in the system. This inspection should be performed at least annually (monthly for American College of Radiology accreditation), with a checklist for documentation. An example of this checklist is provided on the Evolve website. The inspection should include the control console, overhead tube crane, radiographic table, protective lead apparel, and miscellaneous equipment. 视觉检查包括检查设备的主要组件，以确保系统中没有危险、失效、未对准或操作不当的项目。此检查应至少每年进行一次（美国放射学会认证要求每月进行一次），并需有检查清单进行记录。该检查清单的示例可在 Evolve 网站上找到。检查应包括控制台、吊顶管吊车、放射摄影桌、防护铅服和其他杂项设备。
Control Console 控制台
The control console contains all the selectors for controlling X -ray production ( mAs,kVp\mathrm{mAs}, \mathrm{kVp}, and the various meters that monitor the operation of the generator). Control console inspection includes verifying the proper function of X-ray tube heat sensors and the overload protection indicator (discussed later in this chapter). The proper functioning of all panel lights, meters, and switches must be verified as well. The exposure switch must be at least 30 inches from any opening and fixed to the control console. The inspection should ensure a proper view of the exposure room through the window (an unobstructed view of the examination table) and the presence of an up-to-date technique chart that is displayed near the control panel. A technique chart provides technical factors, anatomical examination, patient thickness for examination being performed, proper exposure indicator ranges for the digital imaging system in use, and SID needed to make clinical radiographs when the radiographic system is in manual mode. Most states as well as accrediting agencies require that a technique chart relevant to the particular X-ray machine shall be provided or electronically displayed in the vicinity of the control panel and used by all operators. 控制台包含所有用于控制 X 射线产生的选择器（ mAs,kVp\mathrm{mAs}, \mathrm{kVp} ）以及监测发电机操作的各种仪表。控制台检查包括验证 X 射线管热传感器和过载保护指示器的正常功能（将在本章后面讨论）。还必须验证所有面板灯、仪表和开关的正常工作。曝光开关必须距离任何开口至少 30 英寸，并固定在控制台上。检查应确保通过窗口能够清晰地看到曝光室（对检查台的无遮挡视图），并且在控制面板附近展示有最新的技术图表。技术图表提供技术参数、解剖检查、进行检查时患者的厚度、所使用数字成像系统的适当曝光指示范围，以及在放射系统处于手动模式时制作临床放射照片所需的 SID。 大多数州以及认证机构要求提供与特定 X 射线机相关的技术图表，或在控制面板附近电子显示，并由所有操作员使用。
Overhead Tube Crane 天车
The overhead tube crane is the mounting bracket that holds the X-ray tube over the X-ray table. Items to evaluate in this section include the condition of the high-voltage cables and other wires (are they discolored or frayed?); the condition of the cable brackets, clamps, or tie-downs (are they intact and functioning normally?); the stability of the system; proper movement; SID and angulation indicator function (discussed later in this chapter); detent operation; lock function; 吊车是支撑 X 射线管在 X 射线桌子上方的安装支架。本节中需要评估的项目包括高压电缆和其他电线的状况（它们是否变色或磨损？）；电缆支架、夹具或固定装置的状况（它们是否完好并正常工作？）；系统的稳定性；正确的移动；SID 和角度指示器的功能（在本章后面讨论）；卡位操作；锁定功能；
Fig. 5.8 Image of lead apron with a large hole in the center. 图 5.8 中心有大孔的铅围裙图像。
the bucky center light; collimator light brightness (discussed later in this chapter); and interlock function. Also, ensure that there are no oil leaks around the X-ray tube and generator, and that these are free from dust. 巴基中心光；准直器光亮度（在本章后面讨论）；以及联锁功能。此外，确保 X 射线管和发电机周围没有油泄漏，并且这些设备没有灰尘。
Radiographic Table 放射线检查台
A patient is usually in contact with the X-ray table throughout the diagnostic procedure, so it must be kept clean and safe. Items to inspect include surface condition and cleanliness of the tabletop, power top and angulation switches, bucky tray and cassette locks, stability, table angulation indicator (use a protractor to verify the indicator is accurate to within +-2\pm 2 degrees), and the condition of any footboard or shoulder braces. The tabletop material over the bucky area should not absorb more than 1.0 mm of aluminum equivalent. 患者在整个诊断过程中通常与 X 光桌保持接触，因此必须保持其清洁和安全。检查项目包括桌面的表面状况和清洁度、电源开关和角度开关、Bucky 托盘和胶卷锁的状态、稳定性、桌面角度指示器（使用量角器验证指示器的准确度在 +-2\pm 2 度以内）以及任何脚踏板或肩部支架的状况。Bucky 区域上桌面的材料不应吸收超过 1.0 毫米的铝当量。
Protective Lead Apparel 防护铅服装
Lead aprons and gloves should be present in the radiographic room and should have a minimum 0.25 mm of lead-equivalent thickness. Standards set forth by accrediting agencies dictate that healthcare organizations must perform routine inspections on protective lead apparel for defects such as holes, cracks, and tears on an annual basis. These checks may be performed by visual or tactile means or X-ray imaging. If X-ray imaging is utilized, they can be radiographed or viewed fluoroscopically (with remote fluoroscopy if possible) on acceptance and then every 6 months thereafter to determine whether any cracks or holes are present (Fig. 5.8). If a defect is found, protective devices shall be replaced or removed from service until repaired. Keep a record of when these inspections are performed, as well as the results and any corrective action as documentation for accrediting agencies. Software programs are available for maintaining these inspection reports. When not in use, protective lead apparel should be properly hung on clothing hangers to prevent cracks. Lead vinyl sheets and gonadal shields also should be evaluated in the same manner. If a piece of lead protective apparel is no longer usable, it must be disposed of in an appropriate manner. According to the Health Physics Society, lead and other heavy metals meet 铅围裙和手套应在放射室内配备，且应具有至少 0.25 毫米的铅当量厚度。认证机构制定的标准要求医疗机构每年对防护铅服装进行例行检查，以发现孔洞、裂缝和撕裂等缺陷。这些检查可以通过目视或触觉方式进行，或使用 X 射线成像。如果使用 X 射线成像，可以在接受时进行放射检查或荧光透视（如果可能，使用远程荧光透视），然后每 6 个月进行一次，以确定是否存在裂缝或孔洞（见图 5.8）。如果发现缺陷，防护设备应被更换或在修复之前停止使用。请记录这些检查的时间、结果以及任何纠正措施，以作为认证机构的文档。可使用软件程序来维护这些检查报告。在不使用时，防护铅服应妥善悬挂在衣架上，以防止裂缝。铅乙烯基片和生殖腺屏障也应以相同方式进行评估。 如果一件铅防护服不再可用，必须以适当的方式处理。根据健康物理学会，铅和其他重金属符合
the criteria for hazardous materials under the Resource Conservation and Recovery Act. The best option for disposal is to recycle the protective apparel so the lead can be reused. 根据《资源保护与恢复法》，危险材料的标准。最佳的处置选项是回收防护服，以便重用铅。
Miscellaneous Equipment 杂项设备
A measuring caliper should be present in radiographic rooms in which the manual technique is used along with a technique chart to establish the correct exposure factors. Ensure that positioning sponges and other patient position aids are clean and free of contrast media. Check the manual integrity of any stepstools or intravenous fluid stands as well. 在使用手动技术的放射室中，应配备测量卡尺，并配有技术图表以确定正确的曝光因素。确保定位海绵和其他患者定位辅助工具干净且不含对比剂。同时检查任何脚凳或静脉输液架的手动完整性。
Environmental Inspection 环境检查
Environmental inspection should be performed at least annually (it may need to be performed more frequently with older equipment), and it involves general observation of mechanical and electrical integrity and stability. Often, it can be performed along with the visual inspection. 环境检查应至少每年进行一次（对于旧设备，可能需要更频繁地进行），其内容包括对机械和电气完整性及稳定性的一般观察。通常，这可以与目视检查同时进行。
Mechanical Integrity-Key items to look for are the presence of loose or absent screws, bolts, or other structural elements that may have been improperly installed or have worked loose due to use. The functioning of meters, dials, and other indicators should be checked. 机械完整性 - 需要注意的关键项目包括松动或缺失的螺丝、螺栓或其他可能因安装不当或因使用而松动的结构元素。应检查仪表、刻度盘和其他指示器的功能。
Mechanical Stability-Of key importance from the equipment side are the stability and stiffness of the X-ray tube support and image receptor (i.e., table bucky or wallmounted cassette holder). The mechanical condition of the X-ray tube counterweights and tracks (especially in overhead tube stands) must also be included in the environmental inspection. Lubricate the moving parts. The availability and adequacy of patient support devices such as the table or immobilizing devices should also be checked. In addition, it is important to check the reproducibility of positioning of the source and image receptor that may be indicated or controlled by physical marks or detents. A check of the accuracy of angulation scale should be made. As part of the check of structural stability, an inspection of the electrical and/or mechanical locks on the machine should be carried out. 机械稳定性 - 从设备方面来看，X 射线管支撑和图像接收器（即桌面 Bucky 或壁挂式胶卷盒）的稳定性和刚度至关重要。X 射线管的平衡重和轨道的机械状况（特别是在悬挂式管架中）也必须纳入环境检查。润滑活动部件。还应检查患者支撑设备的可用性和充分性，例如桌子或固定装置。此外，检查源和图像接收器的定位重现性也很重要，这可能通过物理标记或定位器进行指示或控制。应检查角度刻度的准确性。作为结构稳定性检查的一部分，应对机器上的电气和/或机械锁进行检查。
Electrical Integrity-One item included in this portion of the environmental inspection is evaluation of the condition of the X-ray tube high-tension cables, which is accomplished by checking the covering on the outside of the cables (or any other wires that are visible on the outside of the unit). Any discoloration of the outside insulation, especially where the wire or cable bends, could be an indicator of internal heat and a potential short circuit. Check to make sure that the retaining rings at the termination points are tight and that there are no breaks in the insulation. It is important to observe the “lay” of the cables. If they do not hang properly, they can interfere with the positioning of the tube and may fail prematurely. Consult a biomedical engineer, medical physicist, or vendor service technician if discoloration is present. 电气完整性——环境检查中包含的一项内容是评估 X 射线管高压电缆的状况，这通过检查电缆外部的绝缘层（或任何其他在设备外部可见的电线）来完成。外部绝缘层的任何变色，尤其是在电线或电缆弯曲的地方，可能是内部过热和潜在短路的指示。检查终端点的固定环是否紧固，并确保绝缘层没有破损。观察电缆的“铺设”非常重要。如果电缆悬挂不当，可能会干扰管的位置，并可能导致提前失效。如果出现变色，请咨询生物医学工程师、医学物理学家或供应商服务技术人员。
Electrical Safety-Electrical safety is critical for both the patient and the equipment operator. The system should be checked by a safety engineer. This involves a physical 电气安全——电气安全对患者和设备操作员都至关重要。该系统应由安全工程师进行检查。这涉及到物理
Fig. 5.9 The noninvasive evaluation of radiation output system is a microprocessor that can be programmed to acquire and analyze exposure data, providing quality control test results for numerous parameters. 图 5.9 非侵入性辐射输出系统的评估是一个微处理器，可以被编程以获取和分析曝光数据，为多个参数提供质量控制测试结果。
inspection of the electrical wiring. Key areas where problems often occur include the power cord to light indicators in the beam limitation system, the wires to the exposure hand switch, and other similar power hookups. Verify that all elements are well grounded (to each other and to the ground). All radiographic equipment should be electrically grounded, and all obvious electrical connections should be intact. 电气线路的检查。常见问题发生的关键区域包括光束限制系统中的电源线到指示灯、曝光手动开关的电线以及其他类似的电源连接。确认所有元件均良好接地（相互之间及接地）。所有放射线设备应电气接地，所有明显的电气连接应完好无损。
Should the possibility of a short circuit exist, never touch an electrical device with one hand while the other hand is touching any type of conductor; doing so directs the flow of electricity through the heart. If someone is experiencing an electric shock, do not grasp the person directly. Instead, either open the main switch (turn off the power) or use some type of insulator (dry wooden board) to separate the person from the source of the electricity. A good rule of thumb to remember when dealing with electric current is that the combination of high voltage and low amperage tends to throw a person, whereas a combination of low voltage and high amperage tends to hold a person and is potentially more dangerous. For older equipment or equipment that has a history of problems with electrical safety, a biomedical engineer, medical physicist, or vendor service technician should be consulted for environmental inspections (you may also wish to have them accompany you during these inspections). Many states require that an electrical inspection record be posted on the equipment. 如果存在短路的可能性，切勿用一只手触摸电器，同时另一只手接触任何类型的导体；这样会使电流通过心脏。如果有人正在经历电击，切勿直接抓住该人。相反，应打开主开关（切断电源）或使用某种绝缘材料（干木板）将该人与电源隔离。处理电流时，一个好的经验法则是，高电压和低电流的组合往往会使人被抛开，而低电压和高电流的组合则往往会使人被固定住，并且可能更危险。对于较旧的设备或有电气安全问题历史的设备，应咨询生物医学工程师、医学物理学家或供应商服务技术人员进行环境检查（您也可以希望他们在这些检查期间陪同您）。许多州要求在设备上张贴电气检查记录。
Performance Testing 性能测试
Performance testing evaluates the performance of the X-ray generator and X-ray tube with specialized test instrumentation, which can range from simple phantoms and test tools to sophisticated computerized systems such as the RaySafe X2 X-ray Measurement System (Fig. 5.9) or similar devices available from various manufacturers. These computerized systems make the data gathering for performance evaluations quick and easy, but they can cost thousands of dollars. It is more common for facilities to use several smaller devices to 性能测试评估 X 射线发生器和 X 射线管的性能，使用专门的测试仪器，这些仪器可以从简单的幻影和测试工具到复杂的计算机化系统，如 RaySafe X2 X 射线测量系统（图 5.9）或其他各种制造商提供的类似设备。这些计算机化系统使性能评估的数据收集变得快速而简便，但它们的成本可能高达数千美元。设施通常更倾向于使用几种较小的设备来进行测试。
Fig. 5.10 Schematic diagram of an ion chamber. 图 5.10 离子室的示意图。
Much of the data obtained during performance testing include radiation measurement; therefore some type of radiation detector is a standard piece of equipment for many of these tests. The more common type of detector used in performance testing is the gas-filled chamber. As radiation enters this chamber, it ionizes the gas along its path (Fig. 5.10), which produces a trail of ions that allows the flow of current through the chamber for a split second. This current is converted to a voltage pulse that is amplified and counted. The size of the voltage pulse is proportional to the energy expended in the chamber by the incident radiation. A quenching material may be added to the chamber to speed the return of ions to a stable state. There are three types of gas-filled chamber detectors, which vary according to the chamber voltage (Fig. 5.11): the ion chamber, the proportional counter, and the Geiger-Müller counter. 在性能测试中获得的大部分数据包括辐射测量，因此某种类型的辐射探测器是许多测试的标准设备。性能测试中使用的更常见的探测器类型是气体充填室。当辐射进入该室时，它会沿路径电离气体（图 5.10），产生一条离子轨迹，使电流在室内流动一瞬间。该电流被转换为电压脉冲，并被放大和计数。电压脉冲的大小与入射辐射在室内消耗的能量成正比。可以向室内添加一种淬灭材料，以加速离子返回稳定状态。气体充填室探测器有三种类型，依据室内电压的不同而有所变化（图 5.11）：电离室、比例计数器和盖革-穆勒计数器。
Ion chamber. With 100-300 V placed on it, the ion chamber is the least sensitive of the three chambers. The ion chamber is useful for measuring X-rays because a high sensitivity is not required for their detection; ion chambers are often used 离子室。在其上施加 100-300 伏电压时，离子室是三种室中灵敏度最低的。离子室在测量 X 射线时非常有用，因为检测它们并不需要高灵敏度；离子室通常被使用。
Fig. 5.12 Digital dosimeter. (Courtesy Gammex/RMI, Middleton, Wisconsin.) 图 5.12 数字剂量计。（感谢 Gammex/RMI，威斯康星州米德尔顿。）
in performance testing. They usually are available as pocket ionization chambers (also called pocket dosimeters) and analog or digital dosimeters (Fig. 5.12). They also can be used as the sensor in automatic exposure control (AEC) systems and as the detectors in computed tomographic scanners. 在性能测试中。它们通常以口袋电离室（也称为口袋剂量计）和模拟或数字剂量计的形式出现（图 5.12）。它们还可以作为自动曝光控制（AEC）系统中的传感器，以及计算机断层扫描仪中的探测器。
Proportional counter. A voltage of 300-900300-900 V placed on the chamber increases the sensitivity. Proportional counters are often used in stationary laboratory counters to measure small quantities of radioactive material. 比例计数器。在腔体上施加 300-900300-900 V 的电压可以提高灵敏度。比例计数器通常用于静态实验室计数器，以测量少量放射性物质。
Geiger-Müller counter. A voltage of 900-1200 V placed on the chamber yields the greatest sensitivity. Geiger-Müller counters often are used for contamination control in nuclear medicine departments. 盖革-穆勒计数器。施加在腔体上的 900-1200 伏电压可获得最大的灵敏度。盖革-穆勒计数器常用于核医学部门的污染控制。
Some newer types of radiation-monitoring devices use a solid-state or semiconducting detector instead of an ionization chamber. These models incorporate a crystal of either silicon or germanium with selected impurities (such as lithium) added to detect the incident radiation. When the crystal is attached to an electric current, little or no current can flow through the crystal because no free electrons are available. 一些较新的辐射监测设备使用固态或半导体探测器，而不是电离室。这些型号采用了掺有选定杂质（如锂）的硅或锗晶体来探测入射辐射。当晶体连接到电流时，由于没有自由电子可用，几乎没有电流能够通过晶体流动。
If the crystal is exposed to radiation, electrons are dislodged within its matrix and electric current can flow through it. The increase in current is proportional to the amount of radiation incident on the crystal and is registered with an analog or digital meter. This type of detector is relatively small and accurate but usually costs more than ionization chambers. It is also more sensitive than a gas-filled chamber. In most gases, an average energy of 30-4030-40 electron volts (eV) is expended per ion pair produced. In a silicon semiconductor, an ion pair is produced for each 3.5 eV deposited by the incident radiation. For germanium detectors, only 2.9 eV are required to produce an ion pair, which means many more ion pairs are produced in semiconductor detectors (compared with ion chambers) for a given amount of energy absorbed. 如果晶体暴露在辐射下，电子会在其基体内被驱逐，电流可以通过它流动。电流的增加与照射在晶体上的辐射量成正比，并通过模拟或数字仪表进行记录。这种类型的探测器相对较小且准确，但通常比电离室更昂贵。它的灵敏度也高于充气室。在大多数气体中，每产生一个离子对平均消耗 30-4030-40 电子伏特（eV）的能量。在硅半导体中，每吸收 3.5 eV 的辐射能量会产生一个离子对。对于锗探测器，仅需 2.9 eV 即可产生一个离子对，这意味着在给定的吸收能量下，半导体探测器产生的离子对数量远多于电离室。
The value obtained from the radiation detector is most often the radiation intensity, which can be measured in a special unit called the Roentgen ( R ), in an International System of units called coulomb per kilogram ( C//kg\mathrm{C} / \mathrm{kg} ), or in air kerma, 从辐射探测器获得的值通常是辐射强度，可以用一种特殊单位称为伦琴（R）来测量，或在国际单位制中称为库仑每千克（ C//kg\mathrm{C} / \mathrm{kg} ），或以空气剂量（air kerma）表示
which uses an International System or units called the Gray (Gy). KERMA is an acronym for kinetic energy released in matter and measures the amount of kinetic energy transferred into charged particles (such as electrons) by X-rays or gamma rays. It is expressed in units of joules per kilogram or gray. Air kerma is often used instead of the traditional SI unit of C//kg\mathrm{C} / \mathrm{kg} to express radiation intensity. 1R=8.76mGy1 \mathrm{R}=8.76 \mathrm{mGy} of air kerma. 使用一种称为戈瑞（Gy）的国际单位制。KERMA 是“物质中释放的动能”的缩写，测量 X 射线或伽马射线转移到带电粒子（如电子）中的动能量。它以焦耳每千克或戈瑞为单位表示。空气 KERMA 通常用于代替传统的国际单位制单位 C//kg\mathrm{C} / \mathrm{kg} 来表示辐射强度。 1R=8.76mGy1 \mathrm{R}=8.76 \mathrm{mGy} 的空气 KERMA。 K_("air ")(Gy)=0.00876(Gy//R)xx(R)K_{\text {air }}(G y)=0.00876(G y / R) \times(R), so 1 Gy is approximately equal to 100 Roentgen. 1 Gy 大约等于 100 伦琴。
Because both units measure a relatively large amount of radiation, smaller increments of milliroentgens ( mR ) or microcoulombs per kilogram ( muC//kg\mu \mathrm{C} / \mathrm{kg} ) are most often obtained during performance testing. Some detectors are designed so that the exposure rate (intensity of radiation per unit of time) can be displayed in addition to the radiation intensity, and they are known as rate meters. Detectors also can be calibrated to measure absorbed dosage in rads or grays. One rad is equivalent to 0.01 Gy or 1 cGy . 由于这两种仪器测量相对较大的辐射量，因此在性能测试中通常获得较小的毫伦琴（mR）或每千克微库仑（ muC//kg\mu \mathrm{C} / \mathrm{kg} ）增量。一些探测器的设计使得除了辐射强度外，还可以显示曝光率（单位时间内的辐射强度），这些探测器被称为速率计。探测器还可以校准以测量吸收剂量，单位为伦琴（rads）或戈瑞（grays）。1 rad 等于 0.01 Gy 或 1 cGy。
Reproducibility of Exposure 暴露的可重复性
An X-ray generator should always produce the same intensity of radiation each time the same set of technical factors is used to make an exposure. For example, if 80kVp,500mA80 \mathrm{kVp}, 500 \mathrm{~mA}, and 0.02 second yields 100 units of radiation when measured with a dosimeter, then at any future time when the same technical factors are entered into the same X-ray generator, the yield, when tested, should also be 100 units. This concept is known as reproducibility. The maximum variability allowed in reproducibility is +-5%\pm 5 \% according to (1020.31(b)), 21 Code of Federal Regulations Subchapter J. Evaluation of reproducibility variance requires a dosimeter, unless a computerized noninvasive system is used. Reproducibility testing should be performed after equipment installation, after a major system repair, and then annually. X 射线发生器在每次使用相同的技术参数进行曝光时，应始终产生相同强度的辐射。例如，如果 80kVp,500mA80 \mathrm{kVp}, 500 \mathrm{~mA} ，并且 0.02 秒的曝光量在剂量计测量时产生 100 单位的辐射，那么在未来任何时间，当相同的技术参数输入到同一台 X 射线发生器时，测试时的产量也应为 100 单位。这个概念被称为可重复性。根据（1020.31(b)），21 联邦法规子章 J，允许的可重复性最大变异性为 +-5%\pm 5 \% 。评估可重复性方差需要使用剂量计，除非使用计算机化的非侵入性系统。可重复性测试应在设备安装后、重大系统维修后以及每年进行一次。
PROCEDURE: REPRODUCIBILITY OF EXPOSURE 程序：暴露的可重复性
Place a lead apron on top of a radiographic tabletop with the center of the lead apron in the approximate center of the tabletop. Place a dosimeter on top of the lead apron. The lead apron absorbs backscatter from the tabletop material, which reduces the accuracy of any readings obtained. If a lead apron is unavailable, substitute a sheet of lead vinyl. Center the central ray of the X-ray beam on the dosimeter using a SID of 40 inches. Collimate the beam so that the X-ray field is just slightly larger than the dosimeter or remote probe. 在放射摄影台上放置一块铅围裙，铅围裙的中心大致位于摄影台的中心。将剂量计放在铅围裙上方。铅围裙吸收来自摄影台材料的反向散射，这会降低所获得读数的准确性。如果没有铅围裙，可以用一张铅乙烯基替代。使用 40 英寸的 SID 将 X 射线束的中心射线对准剂量计。调整光束，使 X 射线场略大于剂量计或远程探头。
Make a series of three to five separate exposures of the dosimeter at 80 kVp and 10 mAs . Clear the dosimeter (reset to zero) after each exposure. Record each reading on some type of documentation form, such as the Radiographic Survey Form found on the Evolve website. 进行三到五次独立的剂量计曝光，使用 80 kVp 和 10 mAs。每次曝光后清零剂量计。将每次读数记录在某种文档表格上，例如 Evolve 网站上的放射摄影调查表。
PROCEDURE: REPRODUCIBILITY OF EXPOSURE-cont'd 程序：暴露的可重复性-续
With the readings obtained, use the following equation to determine reproducibility variance: 根据获得的读数，使用以下方程来确定可重复性方差：
Reproducibility variance ==((" Exposure or air kerma "_(max)-" exposure or air kerma "_("min ")))/((" Exposure or air kerma "_(max)+" exposure or air kerma "_("min ")))\frac{\left(\text { Exposure or air kerma }_{\max }-\text { exposure or air kerma }_{\text {min }}\right)}{\left(\text { Exposure or air kerma }_{\max }+\text { exposure or air kerma }_{\text {min }}\right)} 可重复性方差 ==((" Exposure or air kerma "_(max)-" exposure or air kerma "_("min ")))/((" Exposure or air kerma "_(max)+" exposure or air kerma "_("min ")))\frac{\left(\text { Exposure or air kerma }_{\max }-\text { exposure or air kerma }_{\text {min }}\right)}{\left(\text { Exposure or air kerma }_{\max }+\text { exposure or air kerma }_{\text {min }}\right)}
