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Penile plethysmography (PPG) or phallometry is measurement of bloodflow to the penis. The most commonly reported methods of conducting penile plethysmography involve the measurement of the circumference of the penis with a mercury-in-rubber or electromechanical strain gauge, or the volume of the penis with an airtight cylinder and inflatable cuff at the base of the penis. Corpus cavernosa nerve penile plethysmographs measure changes in response to inter-operative electric stimulation during surgery. The volumetric procedure was invented by Kurt Freund and is considered to be particularly sensitive at low arousal levels. The easier to use circumferential measures are more widely used, however, and more common in studies using erotic film stimuli. For sexual offenders it is typically used to determine the level of sexual arousal as the subject is exposed to sexually suggestive content, such as pictures, movies or audio. Although there are individuals who have claimed that phallometry is not always appropriate for the evaluation of sexual preferences or treatment effects,〔Simon, W. T., & Schouten, P. G. (1992). The plethysmograph reconsidered: Comments on Barker and Howell. ''Bulletin of the American Academy of Psychiatry and the Law, 20,'' 13-25.〕 large-scale meta-analytic review of the scientific reports demonstrated that phallometric response to stimuli depicting children is the single most accurate (with only 32% accuracy) method of identifying which sexual offenders will go on to commit new sexual crimes.〔Hanson, R. K., & Bussière, M. T. (1998). Predicting relapse: A meta-analysis of sexual offender recidivism studies. ''Journal of Consulting and Clinical Psychology, 66,'' 348–362.〕 For prostatectomy nerve-sparing surgery, the surgeon applies a mild electrical stimulation near the cavernous nerves of penis to verify their locations and avoid operative trauma. Damage to these difficult-to-see nerves can cause erectile dysfunction outcomes. At the surgery's conclusion, the electrical stimulation penile plethysmograph result is a prognosis which helps to manage the erectile function outcomes earlier than the many months required for recovery. ==Types== There are two types of penile plethysmograph: *Volumetric air chamber :When this is placed over the subject's penis, as tumescence increases, the air displaced is measured. *Circumferential transducer :This uses a mercury-in-rubber or indium/gallium-in-rubber ring or electromechanical strain gauge and is placed around the shaft of the subject's penis to measure changes in circumference. The circumferential type is more common,〔Howes, R. J. (1995). A survey of plethysmographic assessment in North America. ''Sexual Abuse: A Journal of Research and Treatment, 7,'' 9-24.〕 but the volumetric method is believed to be more accurate at low arousal levels. Significant suppliers of PPG machines include Behavioral Technology Inc. and Medical Monitoring Systems. The device is known to be used in Brazil, Britain, Canada, China, Czech Republic, Hong Kong, New Zealand, Norway, Slovak Republic, Spain, and the United States. The surgical machine is supplied as CaverMap by Blue Torch Medical Technology, Inc. A roughly equivalent procedure for women, vaginal photoplethysmography, measures blood through the walls of the vagina, which researchers claim increases during sexual arousal. 抄文引用元・出典: フリー百科事典『 ウィキペディア（Wikipedia）』 ■ウィキペディアで「Penile plethysmograph」の詳細全文を読む スポンサード リンク
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