A real inspector would have focused on the powdered substance hiding in my bra, the box cutter tucked into my tights and the plastic-explosive material snuggling inside my dress pocket. But because I was too close to the subject under scrutiny, I fixated on the position of my bellybutton: How strange that it sits so high up on my torso. Get over yourself, honey: The full-body scanning machines at airport security checkpoints weren't created to point out corporeal flaws but to detect suspicious objects lurking beneath airline passengers' clothing. The advanced imaging technology identifies forms that aren't traditionally part of the human physique, such as an oval mound on the hip that could be a potential bomb, or a pen shape near the ankle that might be a knife. Since I hadn't harbored any contraband in my navel, there was no cause for alarm. Yet in a broader context, plenty of people are alarmed. The machines have sparked an electric storm of controversy that touches on such knotty issues as the U.S. government's anti-terrorist strategies and an individual's privacy rights. Compared with body scanning, removing our shoes is as benign as trying on footwear at Payless. To understand the debate from all angles, I decided to undergo a scan, experiencing technology's prying eyes firsthand. Standing before a bank of uncovered windows in a second-floor office in Rosslyn, Va., I bared almost all. If you've ever walked into a boothlike apparatus, stepped on colored footprints and moved your arms like a clumsy cheerleader, you've been body-scanned. The Transportation Security Administration piloted the new technology in 2007 and rolled out 40 of the machines in 19 airports. Last fall, the agency bought 150 imaging machines, and it has since procured funding for 300 more. If all goes according to plan, the TSA will have installed 490 scanners by year's end. 'This enables the officers to identify without any physical contact something concealed under clothing,' said Jonathan Allen, a TSA spokesman. 'We need to have as many different layers of security as we can. When we put them all together, it's more formidable.' The au courant technology addresses a gap in security that garnered critical attention after the failed bombing of a Christmas Day flight to Detroit. X-ray machines catch only metal objects, and explosives trace detectors, such as the sneezelike puffers, collect only the residue of hazardous material. With pat- downs, searchers can detect foreign objects stashed on a person's figure, but private areas, such as the underwear zone of the recent terrorist, are off- limits. 'Unless it's a grope, we never would have found that device,' said Brian Jenkins, a homeland security expert and senior adviser to the president of Rand Corp. 'We can increase the restrictions, or we can deploy another array of hardware.' For now, the TSA has chosen the latter, adding another machine to its already gadget-laden process. 'Since Americans are enamored with technology, we tend to look for a silver bullet,' Jenkins said. 'Will the body scanner add to the security? Yes. Will it solve the problem and prevent all future terrorist attacks? No.' The TSA has approved two types of imaging machines that utilize different technologies but share the same purpose: peeling back a passenger's clothing to reveal suspect objects on the body. With the millimeter-wave model, radio waves bounce off the skin, lighting on foreign substances; the emission is equal to one ten-thousandth of the energy released by a cellphone. The backscatter uses low-level X-rays _ about what you'd be exposed to during a two-minute plane ride _ that seek out energy discrepancies. While the passenger is being scanned, a security official in a remote location studies the captured image for strange shapes and anomalies. The whole procedure takes 15 seconds or less. The millimeter wave transmits a black-and-white 2-D hologram that resembles an overexposed photo of an X-Man gone soft. The backscatter image looks like a body sketch by an amateur artist, unrefined and not worth hanging on the fridge door. 'It's not pornographic; it's not titillating,' said Jenkins. 'I would regard these as the most unerotic images.' Unless you have a hankering for panty lines. Only six airports operate body scanners for primary screening, so unless you depart from one of those locations (such as Miami or San Francisco) or are selected for a secondary inspection, your chances of being scanned are fairly random. Rather than leave it to fate, I arranged an imaging session with Smiths Detection, an engineering firm that designs equipment for the TSA, including a millimeter-wave machine about to be field-tested. (Note: A few weeks later, I requested a scan at the Atlanta airport. Though a TSA official told me that it wasn't 'some amusement park ride,' he directed me to a machine near lanes 1 through 4. The screeners there thought I was strange but apparently not dangerous, as I received an 'all clear; copy that.') In its Rosslyn office the company keeps an array of Security `R' Us toys, some of which looked familiar (X-ray machine), others foreign (a bottle scanner that ascertains the safety of liquids) and one reminiscent of my old Dustbuster (a portable explosives trace detector). The body scanner stood against an unadorned wall opposite a wall of windows. A pair of white footprints faced a tall detection panel as exciting as a clean blackboard. A small computer screen sat on a table within view of the feet. Shannon Town, a Smiths Detection office manager, agreed to go first. As she raised her arms and spun with comfort and ease, I sensed that she was a frequent guinea pig. In fact, Town is such a veteran model that she was able to slip some 'weaponry' under her clothes without attracting notice. Only after studying her image did I detect the smuggled box cutter and explosives stand-in material. 'We are looking at differences in shapes, sizes and densities,' explained vice president Brook Miller. 'You see what you need to see.' Truth be told, I didn't think I needed to see (begin ital) this (end ital)much of Town: her bra straps, the buttons of her pants, her wiggling toes. 'It's better for females than males,' said a male volunteer, who also pranced before the machine with a fake gun tucked into his waistband. 'It looks like what you wear at the beach.' But only if your bathing suit style tends toward Germans on holiday. Body scanners may appeal to the nudists of the world, but a number of (clothed) groups are not so supportive of the technology, viewing it as a threat to an individual's right to privacy. In 2006, the American Civil Liberties Union testified before Congress, questioning the equipment's ability to foil terrorists and raising concerns about potential violations of basic rights. More recently, the Electronic Privacy Information Center filed a Freedom of Information Act lawsuit against the Department of Homeland Security, requesting the images generated by these machines. 'Before the new technology is implemented, there should be evidence of its effectiveness against the threat. The device does not locate well-concealed items in body parts and cavities,' said Michael German, policy counsel at the ACLU, citing as one example a British study that found the scanners inept at detecting low-density materials. 'It's asking a lot of people to sacrifice their privacy for technology that's not effective.' Though many folks may be ashamed of outing their beer paunches, privacy advocates also worry that the machines could violate a person's religious beliefs or cultural customs, or may unnecessarily expose a physical disfigurement or medical condition, such as a colostomy bag. 'With the current threat, this isn't the answer,' German said. 'There are other technologies that don't have these privacy issues.' To address those concerns, the TSA has implemented a number of safeguards. Faces on the images are blurred or covered with a bar, and hair is absent, creating an extended family of look-alike baldies. The Smiths Detection model gender-proofs the review process by matching female inspectors with female passengers and male inspectors with male passengers. Screeners surveying the images are physically separated from the person being scanned, minimizing the risk of an awkward encounter. L-3 Communications, which makes the millimeter-wave scanner, is taking it further: With its new automated version (in use at Amsterdam's Schiphol airport), machine replaces man, highlighting questionable objects on a Gumby-like figure. In addition, the images cannot be saved or stored; the next scan can take place only if the previous picture is erased. Finally, travelers may opt out of the experience and request another type of screening. Note: Plan B could be a pat-down. If a recent poll by USA Today and Gallup is any indication, Americans will be queuing up for the scanners. Seventy percent of those surveyed said that, for comfort reasons, they'd rather undergo a body scan than a pat-down. Another finding: More men than women support its use, with the majority of guys saying they have no qualms about being virtually strip-searched. To prepare for my scan, I had packed some essentials: a screwdriver, a Swiss Army knife, a container of Kiehl's lotion, a fork, a candle and an orange that could be used as a weapon or a snack. However, after seeing the company's buffet of (faux) hazardous material lined up on the countertop, I quickly abandoned my props for theirs. Before entering the chamber, I sneaked into the kitchen to accessorize my body, throwing a small Mini Moo's creamer into my bra at the last minute. Bulked up, I stepped onto the footprints and lifted my arms. My first spin was too fast, so I slowed the pace for the second turn, allowing the waves enough time to penetrate my threads. From my position, I could peek at the screen, and I was impressed: I looked like a terrorist-kicking avatar dressed in a liquid catsuit. Upon closer inspection, my superhero uniform fell away. I noticed the outlines of my underwear, tights and bra, and the mid-waist tie of my dress. A shot of my backside, revealing more than a plumber's peep show, made me realize that I needed to add squats to my exercise routine. I could see the glint of my dangly gold earrings and the white of my teeth. And then there was the odd placement of my navel, a small dot too far north. Of course, America's safety _ not my ego _ was on the line. So I got serious, discerning the various shapes atypical of the basic human form: the crinkly mass above my ribcage (the baggie of sugar), the shine by my shoulder (a paper clip), the dark shadow beside my heart (the Mini Moo's). I was a voodoo doll of danger. Miller eventually deleted my image, but my mind held on to it as I tried to grasp the new bare-it-all phase of airport security. In the end, I found it comforting to know that the body scanner would uncover items missed by older equipment and that we travelers have one more layer of protection against those exceedingly crafty terrorists. For that, I could live with an exposed bellybutton. sachsa@washpost.com 