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The differing physicochemical prop- It is metabolized by the hepatic microsomal Propofol (Phenol derivative) erties of the different volatile agents will enzyme to form no ketamine generic cefdinir 300 mg on line antibiotic cephalexin, which is then Tis drug became commercially available in affect their pharmacological effects (Table hydroxylated to form hydroxynorketamine cheapest generic cefdinir uk infection mod. N2O generic cefdinir 300 mg online antibiotics for uti first trimester, desflurane and sevoflu- ered from the urine and less then 5 percent of soluble and is formulated in a white order generic cefdinir on-line oral antibiotics for acne yahoo answers, aqueous rane will cause rapid onset and recovery injected ketamine undergoes fecal excretion. Recovery is rapid and there is minimal surgical incision in 50 percent of subjects, 3. Oil/gas partition coefcient indicates lipid • Hypotension and fall in peripheral vas- solubility and correlates closely with anes- Contraindications cular resistance are more marked with thetic potency. Propofol is suitable both for induction as An ideal inhalational anesthetic agent would 3. Maintenance dose is be characterized by: 101 Section 4 Specialties Related to Surgery Table 15. Rapid and pleasant induction of and Pharmacologic Properties nism is still not clear. Absence of toxic efects or other adverse which results in bronchodilatation and Halothane should always be used through properties in normal doses. Minimum or no depression of the cardio- • Ether causes good skeletal muscle relaxa- vaporizer. Nausea and vomiting are common from N2O it is associated with malignant depth of anesthesia. It is a matter of regret that none of the Ether Convulsion inhalational anesthetic agents fulfll the prop- Occurs in children and in disease states like Enflurane erties of an ideal agent. It is a halogenated ether and a volatile liquid • It is treated by administration of O2 anesthetic. It was introduced in clinical prac- Classification thiopentone or diazepam and artifcial tice by Dobkin and associates in 1968. It may cause hepatotoxicity and hypothermia Halothane but less commonly than halothane. Diethyl Ether • It was frst prepared by Suckling in 1951 It produces moderate muscular relaxation This is probably the most extensively used and frst used clinically by Johnston of and excreted unchanged through the lungs. The reason for this is its wide safety • Physical properties have been described excreted through the kidney. It produces dose dependent depres- in 1965 and introduced in clinical anesthe- aldehyde in presence of light. It is typically produced by sux- threshold leading to the block of neuromus- the body. Sevoflurane • Teir action is opposed by increasing the A low blood/gas solubility coefcient facili- Suxamethonium local concentration of acetylcholine, e. It is well-suited for outpatient line molecules and acts in the same way at • Teir action is potentiated by certain surgery. Its action there- efect on the cardiovascular and respiratory fore, cannot be reversed. Because it acts on Characteristics of Nondepolarizing systems are similar to isofurane. Myocardium the acetylcholine receptor there is an initial Block is not sensitized to catecholamines. Tere is unsustained response to tetanic stimulation also called the ‘fade’ Nitrous Oxide Clinical Use response. Commonly used nondepolarizing agents (Entonox) is used for analgesia especially Dose: 1 to 1. Prolonged apnea-Some people have • Pancuronium late in the cavities of the body, e. Hyperkalemia-Occurs if it is given in Neuromuscular Blocking Agents patients with burn, tetanus and spinal Clinical Uses cord injury. The addition of muscle relaxants afords the dicated in patients with penetrating eye 2. For maintenance of paralysis during opportunity to deliver only sufcient inhala- injury. Relaxants good recovery of muscle power to maintain Depolarizing and nondepolarizing muscle Tey compete with acetylcholine for the end airway and respiration. Once a signifcant carinic action may induce a profound, brady- Tey act by causing depolarization block and number of receptors are blocked the end plate cardia, bronchoconstriction, etc. Tis technique combines Management of General Inhalation of nitrous oxide, oxygen plus a the advantages of both the intravenous and Anesthesia potent volatile anesthetic, e. Afer thetic drug dosage can be titrated according General anesthesia can be induced by giving induction, a depolarizing or nondepolarizing to the patient requirements. If there is some question about the General anesthesia reduces the tone of the Rapid Sequence Induction difculty of intubation, it can be attempted muscles that preserve the airway patency and Anesthesia is most commonly induced by while the patient is breathing spontaneously, hence there is a requirement for methods the method of rapid sequence induction in without giving a muscle relaxant. Tiopentone) is fol- children or ‘Needle – phobic’ adults and may or endotracheal tube to preserve the airway. Sir lowed by a depolarizing muscle relaxant, also be used for patients at risk of developing Ivan Magill developed the endotracheal tube e. Oxygen is usually given by mask Induction Intubation before hand (Preoxygenation) to allow maxi- Shortacting anesthetic drugs such as thio- 1. To provide positive pressure ventilation, mum time for intubation while the patient is pental, propofol or midazolam are ofen e. Urine output position of the patient is other than supine lution and is usually conducted by infusing 9. Accurate monitoring of vital functions is with the means of resuscitation and with • Accidental intubation of a main bronchus. Even for procedures under sedation, ously ill patient a high dependency unit or • Aspiration of vomitus during intubation. The com- laryngitis and laryngeal or subglottic Clinical Monitoring mon causes of failure to breathe afer general edema. Careful observation of physical signs and of anesthesia decreases, pupils-size, iii. Circulatory failure leading to respiratory capnography of the expiratory gases, inspira- • Nailbeds-Color, capillary refll. Alveolar hypoventilation from opioid ventilator disconnection alarms, are manda- drugs, or anesthetic agents. Following the induction of anesthesia, inha- Spinal, epidural and caudal blocks are lational or intravenous anesthetic agents are Auscultation commonly referred to as regional or administered to maintain an adequate depth • Chest-Ventilation and cardiac sounds. Blood pressure Locoregional anesthesia using local anes- required for maintenance. Skeletal muscle relaxation is excellent, the world, ether has generally been replaced 5. Desfurane and sevofurane are the most Common but not in routine Regional anesthesia is used most ofen recently introduced agents, conferring the 7.
Less commonly generic cefdinir 300mg with visa augmentin antibiotic 625mg, vitrectomy may be performed buy generic cefdinir 300mg online virus on mac computers, and internal drainage of fluid and cholesterol may be accomplished through a retinotomy buy cefdinir uk virus protection. At the same time buy cefdinir master card antibiotics ear drops, it is necessary to treat the abnormal vessels by photocoagulation or cryotherapy. The vision in these eyes, however, is usually quite limited, and sometimes, despite reattachment of the retina, there is no light perception. However, retinal detachment and neovascular glaucoma are the ultimate complications that may lead to loss of the globe. When retinoblastoma cannot be ruled out or when neovascular glaucoma is present in blind, painful eyes. Autoimmunity toward retinal antigens may play a role in specific types of retinitis pigmentosa. Leber T: Uber eine durch Vorkommen multipler Miliaraneurysmen charakterisierte Form von Retinaldegenera-¨ tion. Matsuura S, Shiragami C, Takasu I, et al: Retinal attachment achieved by vitrectomy in two cases of bullous exudative retinal detachment. Solomon A, Banin E, Anteby I, Benezra D: Retinitis pigmentosa, Coats disease and uveitis. Tarkkanen A, Laatikainen L: Coats disease: Clinical, angiographic, histopathological findings and clinical management. Blunt trauma to the sclera can produce a direct effect on the underlying choroid and retina. In addition, a concussive effect from force transmitted through the vitreous may be seen away from the initial point of impact. The shearing forces generated by this traction may tear the retina in the area of the vitreous base or result in avulsion of the vitreous base. Indirect damage from the concussive effect of an injury tends to occur at the interfaces of tissue with the greatest differences in density, most commonly the lens–vitreous interface and posterior vitreoretinal interface. The transmitted force may cause fragmentation of photoreceptor outer segments and damage to the receptor cell bodies. Clinically, these areas appear as opacified retina and are termed commotio retinae. Although the retinal whitening is only temporary, resolving over 3–4 weeks, permanent damage may occur. Optic nerve avulsion after severe blunt underlying an area of commotio may trauma. The eponym associated with this entity is Berlin’s edema; however, there is no true intracellular or extracellular edema, and no fluorescein leakage is seen. Retinal dialyses are usually located in the superonasal or inferotemporal quadrants (Fig. Because they can lead to retinal detachment, a careful depressed exam of all patients with a history of blunt trauma is essential. Prophylactic treatment of all dialyses with cryopexy or laser photocoagulation is recommended in the hope of decreasing the likelihood of future retinal detachments. Retinal detachments present at variable intervals after injury; however, the dialysis is usually detectable early or immediately at the time of injury. Approximately 10% of dialysis-related detachments present immediately, 30% within 1 month, 50% within 8 months, and 80% within 2 years. Most trauma victims are young with a formed vitreous that tamponades a break or dialysis, but as the vitreous eventually liquefies, fluid passes through retinal breaks causing detachments. The nature of the vitreous in such cases may explain the delay in presentation of the detachments. Besides retinal dialyses, do other trauma-related breaks need to be treated prophylactically? Horseshoe tears and operculated holes in the setting of acute trauma are usually treated by cryopexy or laser photocoagulation. Macular holes require pars plana vitrectomy with gas exchange if closure of the hole is attempted; however, macular holes usually do not progress to retinal detachments. Direct injury with necrosis of the retina is usually associated with underlying choroidal injury so that a chorioretinal adhesion may be formed spontaneously. However, any accumulation of subretinal fluid or persistent traction on damaged retina makes prophylactic treatment reasonable. What is the prognosis for repair of a retinal detachment associated with a dialysis? The characteristics of the detachment are suggestive of its chronic nature and insidious onset; however, the prognosis for repair with conventional scleral buckling techniques is good. Consequently, it is susceptible to the stretching forces exerted on the globe in blunt trauma. Choroidal ruptures may be found at the point of contact with the globe or in the posterior pole as a result of indirect forces. Clinically, choroidal rupture appears as a single area or multiple areas of subretinal hemorrhage, usually concentric and temporal to the optic nerve (Fig. Choroidal ruptures (large arrows) white area is seen where the rupture located concentric to the optic nerve. The visual consequences of a choroidal rupture depend on its location with respect to the fovea. A patient with a choroidal rupture near the fovea may have good vision; however, the break in Bruch’s membrane predisposes him or her to the development of a choroidal neovascular membrane, which may threaten vision long after the initial injury. Therefore, patients at risk should be followed regularly and advised of the potential complication. High-velocity missile injuries may cause an indirect concussive injury to the globe, resulting in retinal breaks and ruptures in Bruch’s membrane that resemble a claw. A fibroglial scar with pigment proliferation forms, but retinal detachment is rare, possibly because a firm adhesion develops,actingasa retinopexy. The five types of breaks are horseshoe tears, operculated tears, dialyses, retinal dissolution, and macular holes. A dialysis-related detachment has a very high success rate with treatment by scleral buckling. When a laceration or obvious deformation of the globe is not visible, other findings raise the index of suspicion that an injury may be more serious than initially thought. Other findings that may be helpful include a deeper than normal anterior chamber and a low intraocular pressure; however, in an eye with a posterior rupture and incarcerated uvea the intraocular pressure may be normal. The first person to evaluate the traumatized eye may have the only opportunity to assess the best visual acuity. The delay often associated with referral to other institutions or dealing with life-threatening complications may result in diffusion of vitreous hemorrhage and corneal or other anterior segment abnormalities that preclude an adequate view of the posterior segment.
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Early administration of antidepressants might ative correlation between measures of regional blood flow prevent the occurrence of progressive structural and func- in the aforementioned structures discount 300mg cefdinir with visa new antibiotics for sinus infection. It is interesting that high levels of amygdala activation may be associated with an increased prevalence of anxiety symptoms and negative affect Effect of Mood Disorders on (Davidson et al order genuine cefdinir line antibiotic resistance results from. Although Consistent with these findings order cefdinir american express infection behind ear, athletes who have ex- there has been significant progress in determining the fac- perienced a concussion and present with depression tors associated with poor outcome cheap 300 mg cefdinir visa antimicrobial jiu jitsu gi, we are still uncertain symptoms showed reduced activation in the dorsolateral about what are the most successful restorative interven- prefrontal cortex and striatum and gray matter loss in tions. There was a signif- campal volumes were associated with poor vocational out- icant association between poor psychosocial outcome and come at 1-year follow-up (Jorge et al. Patients with short-term chiatric disturbance will certainly have a negative impact depression (i. The results showed a significant association be- different pharmacological and nonpharmacological strate- tween depression and recovery status as measured by the gies. Currently, data derived from small inconclusive tri- that patients with depression or anxiety were more func- als and clinical expertise are the only things that support tionally disabled and perceived their injury and cognitive many of our daily treatment decisions. Another study analyzed the Patients with brain injury are more sensitive to the side association of major depression with behavioral outcome effects of medications, especially psychotropic agents. Individuals who devel- ver and Arciniegas (Chapter 35, this volume) propose sev- oped major depression had objective evidence of poorer eral general guidelines for their use in this population. There is also evidence that Doses of psychotropic medication must be prudently in- the effect of depression on activities of daily living func- creased to minimize side effects (i. Special care must be taken cantly lower Community Integration Questionnaire scores in monitoring drug interactions. Taken together, these stud- of a partial response to a specific medication, augmentation ies emphasize the need of recognizing and treating mood therapy may be warranted, depending on the augmenting and anxiety disorders during the rehabilitation process. We have also examined the effect of a history of alco- There is some preliminary evidence that desipramine hol misuse on vocational outcome at the 1-year follow-up may be effective for treating depression in patients with evaluation. A logistic regression model included age, severity of well as in the severity of postconcussive symptoms (Fann brain injury as measured by Glasgow Coma Scale scores, et al. Sertraline may also lead to a beneficial effect premorbid social functioning as measured by baseline on cognitive functioning (Fann et al. At variables showed that the occurrence of mood disorders 10 weeks, response and remission rates increased to 46. Selection among compet- tients with a history of alcohol misuse returned to their ing antidepressants is usually guided by their side-effect previous occupation or were competitively employed at profiles. Mild anticholinergic activity, minimal lowering the 1-year follow-up compared with 58 (78%) of 74 pa- of seizure threshold, and low sedative effects are the most tients without a history of alcohol misuse (χ2=8. Furthermore, patients with a history of alcohol depressant drug in this population. A duction in negative affect and the use of addictive sub- case report, however, reported adequate control of prob- stances. In addition, there have been brief reports that sug- stress disorder following mild head injuries. Behavioral interventions, such as the Differential ventions, treatment options are based on logic and current Reinforcement of Other Behavior, may successfully re- standards of practice rather than empirically based con- duce the frequency of problematic behavior (Hegel and trolled treatment trials. Arch Gen Psychiatry 61:42–50, 2004 tive complaints following mild traumatic brain injury. Am J Psychiatry 167:312–320, 2010 Adolphs R: Cognitive neuroscience of human social behaviour. Brain Inj 22:471–479, 2008 American Psychiatric Association, 1994 Chaytor N, Temkin N, Machamer J, et al: The ecological validity of American Psychiatric Association: Diagnostic and Statistical neuropsychological assessment and the role of depressive Manual of Mental Disorders, 4th Edition, Text Revision. Br J Psychiatry 150:690– Deb S, Lyons I, Koutzoukis C, et al: Rate of psychiatric illness 692, 1987 1 year after traumatic brain injury. Am J Psychiatry 156:374– Brooks N, Campsie L, Symington C, et al: The five year outcome of 378, 1999 severe blunt head injury: a relative’s view. J Head Trauma Re- nitive response to human traumatic brain injury: a quantita- habil 13:10–22, 1998 tive proton magnetic resonance study. Neurology 54:895–902, 2000 disorder and psychosocial functioning after severe traumatic Donnemiller E, Brenneis C, Wissel J, et al: Impaired dopaminergic brain injury. J Neu- axis responses to provocative challenge tests in adult survi- ropsychiatry Clin Neurosci 12:226–232, 2000 vors of childhood abuse. J Neurol the Rivermead Post-Concussion Symptoms Questionnaire in Neurosurg Psychiatry 72:615–620, 2002 mild-to-moderate traumatic brain injury patients. Curr Opin Neurol 14:753–757, use of mental health services, and attrition from military ser- 2001 vice after returning from deployment to Iraq or Afghanistan. J Neuropsychiatry Clin Neurosci 5:43–49, 1993b and cellular actions of current mood stabilizers. Brain Inj imaging: correlates with neuropsychological and psychological 22:705–714, 2008 outcome in traumatic brain injury. J Neurol Neurosurg Psychiatry 44:527–533, 1981 sociation between two polymorphisms in the serotonin Moghaddam B, Jackson M: Effect of stress on prefrontal cortex transporter gene and affective disorders. Psychiatr Genet and sensation seeking among African-American cocaine- 14:121–129, 2004 dependent individuals. Genes Brain Behav following traumatic brain injury: a potential role for neu- 3:328–336, 2004 rotrophin-4/5 in pyramidal cell neuroprotection. Curr Treat in the dorsolateral prefrontal cortex in schizophrenia, bipo- Options Neurol 4:477–486, 2002 lar disorder, and major depression. Synapse 51:112–118, Schoenhuber R, Gentilini M: Anxiety and depression after mild 2004 head injury: a case control study. Biol Psychiatry 55:244–249, 2004 Whyte J, Vaccaro M, Grieb-Neff P, et al: Psychostimulant use in Shiozaki T, Akai H, Taneda M, et al: Delayed hemispheric neu- the rehabilitation of individuals with traumatic brain injury. Thanks to improved protective equipment, soldiers ogy, including psychosis, has been suggested since the are better able to survive injuries that would previously nineteenth century. Early in the twentieth century, Emil have been fatal, but such injuries frequently entail brain Kraepelin (1919) hypothesized that brain injuries in child- injuries. About one-third of the (American Psychiatric Association 1987) and 102 of their posttraumatic psychosis group had a clinical picture re- unaffected siblings. Subjects in the schizophrenia group sembling schizophrenia, with paranoia and hallucina- were more likely to have had childhood head injury. The subjects of these reports ranged from civil- of Posttraumatic Psychosis ians incurring concussions to soldiers suffering combat in- jury. Location of Injury Davison and Bagley noted that the incidence of psychosis increased over time and that many individuals did not be- Accumulated evidence suggests that injuries to the left come psychotic until years after the injury. In comparing hemisphere and to the temporal lobes may be most closely this range of 0. Hillbom (1960) found that 40% of indi- lation over a period of 25 years, Davison and Bagley con- viduals with posttraumatic psychosis had temporal lobe cluded that brain trauma increased the observed incidence injuries, which was a higher proportion than in those with of psychosis by two- to threefold over a period of 10–20 nonpsychotic psychiatric disturbance. Hillbom (1960) found review of five studies published between 1932 and 1961, that the rate of psychosis increased with the severity of the Davison and Bagley (1969) found the frequency of premor- injury: 2. However, other (3/25), birth complications (2/25), attention-deficit/hyper- studies have not found severity of injury to be a predictor activity disorder (1/25), and congenital syphilis (1/25). Type of Injury There is inconsistent evidence on whether type of head in- Posttraumatic Epilepsy jury is related to psychosis risk.
The higher the grid ratio purchase cefdinir cheap win32 cryptor virus, the nar projected images of the lead strips are rower the exposed area generic cefdinir 300 mg visa virus like ebola. With Lateral Decentering linear grids there may be uniform light ening of the whole flm purchase cefdinir with visa infection xp king, one edge of the Lateral decentering results from the x ray tube being positioned lateral to the con vergent line but at the correct focal distance (Fig buy cefdinir canada antimicrobial hypothesis. All the lead strips cut off the 1\ same amount of primary radiation, so,, there is a uniform loss of radiation over,,, the entire surface of the grid, producing,,, a uniformly light radiograph. This is prob,, ably the most common kind of grid cutoff,,,,, but it cannot be recognized by inspection,, of the flm. All we see is a light flm that is,, usually attributed to incorrect exposure factors. Figure 8-12B shows a series of flm strips that were all taken with the same exposure factors, but with increasing amounts of lateral decentering. Three factors affect the magnitude of The loss of primary radiation for any given cutoff from lateral decentering: grid ratio, amount of lateral decentering can be min focal distance, and the amount of decen imized with low-ratio grids and a long focal tering. If the grid rb ratio is increased to 16: 1, the loss of pri L =- X 100 fo mary radiation increases to 45%, and if the L = loss of primary radiation (%) focal distance is then decreased to 40 in. When a linear grid is Figures 8-14 and 8-15 show the cutoff be tilted, as it frequently is in portable radi coming progressively greater with increas ography, there is a uniform loss of primary ing distance from the flm center. The cen radiation across the entire surface of the tral portion of the flm is not affected, but grid (Fig. Because the frac the same as the effect of lateral decenter tional loss of radiation is not uniform, it mg. The loss of primary radiation target of the x-ray tube is correctly cen is directly proportional to the grid ratio and tered to the grid, but it is positioned above distance from the center line. If the target is above the convergent line, it is called far focus-grid distance decentering; if the tar get is below the convergent line, it is called near focus-grid distance decentering. With far focus-grid distance decentering, the loss at the film margin de creases to 21% for a 6: l grid and 64% for a 16: l grid. Parallel grids are focused at infinity so, of course, they are always used with near focus-grid distance decentering (Fig. The only time there is no significant cutof is with long target-grid distances or small fields. A film taken with a parallel grid has a dark center and light Transmitted edges because of near focus-grid distance decentering. Figure 8-15 Cutoff from far focus-grid dis Combined Lateral and Focus-Grid tance decentering Distance Decentering The most commonly recognized kind of The equations for calculating the loss of grid cutoff is from combined lateral and primary radiation for near and far focus focus-grid distance decentering. It is prob grid distance decentering are as follows: ably not as common as lateral decentering Near Focus-Grid Far Focus-Grid alone, but lateral decentering cannot be Distance Decentering Distance Decentering recognized as such on the resultant radio graph. It causes an uneven exposure, resulting in a flm that is light on one side L = loss of primary radiation at point c (%) and dark on the other side. There are two r = grid ratio kinds of combined decentering, depending f0 = grid focusing distance on whether the tube target is above or be f, = target-grid distance (below low the convergent line. The amount of convergent line; inches), cutoff is directly proportional to the grid f2 = the target-grid distance (above ratio and decentering distance, and in convergent line; inches) versely proportional to the focal distance c = distance from center of grid (inches) of the grid. With high-ratio grids and large Table 8-6 shows the extent of cutoff at decentering errors, there is a large loss of various distances from the center of grids primary radiation. Potter in 1920 and, for many centering below the convergent line is il years, a moving grid was called a Potter lustrated in Figure 8-18. In recent years the name has images of the lead strips are broader on been shortened to Bucky grid, which is un the side opposite the tube target than on fortunate, because the name of the inven the same side, and the film is light on the tor is omitted. With equal decentering moving grids are reciprocating, which errors the amount of cutoff is greater with means they continuously move 1 to 3 em combined decentering below the conver back and forth throughout the exposure. Between pulses, the grid moves one interspace distance so that the next lead strip is over the position of the preceding strip and, with a new pulse, the two images are superimposed. They are costly, subject to failure, may vibrate the x-ray table, and put a limit on the minimum exposure time because they move slowly. Because the grid moves 1 to Film 3 em during the exposure, the tube is not Figure 8-18 Cutoff from combined lateral centered directly over the center of the grid and near focus-grid distance decentering during most of the exposure. Older grids move only as 20% of the primary radiation with a in one direction and must be cocked for high-ratio grid and a short focusing dis each exposure. With the iden Moving grids are advantageous because tical number of photons per unit area, a they eliminate grid lines from the film. The total methods, however, grids have improved so quantity of density (blackness) on the flm that grid lines are not nearly as distracting, is represented by the water level in Figure and many radiologists now prefer station 8-19A. In Figure 8-l9B a grid is im to avoid grid lines, you must take two pre mersed in the water to represent the grid cautions. If it moves too slowly, you will see either the grid lines themselves or random density variations in the flm that are just as distracting as the lines. Second, the transverse motion of the grid should be synchronous with the pulses of the x-ray generator. When this happens, the shadow of each lead strip is superim posed on the shadow of its neighbor. The total quantity of The effciency of scatter radiation ab density on the flm is the same with both sorption by various grids is shown in Figure moving and stationary grids, but with sta 8-20, which plots the fractional transmis tionary grids the flm is made up of many sion of scatter radiation against grid ratio. The im There is no simple rule to guide the cli provement in film quality in going from a nician in choosing a grid for any particular 12:1 to a 16:1 grid is not worth the greater situation. Scat grids will give adequate results below 90 ter radiation arising in the patient from kVp. Above 90 kVp, 12:1 grids are pre Compton reactions disperses in all direc ferred. Crossed grids are only used when tions, so the patient acts like a large light bulb (Fig. In the illustration, scat tered photons are shown radiating out z 0 from a point source, but the point actually � 1. Each ray Q represents a separate scattering event, and � numerous scatterings within the small G Q block produce the array shown. Scatter radiation decreases not from I fltration but from scattered photons miss i I ing the flm. With cause a natural "gap" separates the flm increasing energy, more photons scatter in from the scattering site. The difference in the forward direction, but the increase is the contribution from the two sides is even negligible in the diagnostic range. Many the energy of the incident photon is in scattered photons from the input surface creased from 10 to 140 keV, a much greater (Fig. You can see from from superfcial tissue blocks on opposite the illustration that the air gap is most ef sides of the patient. More radiation reaches fective in removing scatter radiation when the flm from scattering near the exit sur the scatter originates close to the film (Fig.