except as otherwise noted , the articles “ a ,” “ an ,” and “ the ” mean “ one or more .” fig1 illustrates a dxa system 10 . the dxa system 10 includes a patient table 12 having a support surface 14 that can be considered horizontal and planar in this simplified explanation and illustration , which is not necessarily accurate in scale or geometry and which is used here solely to illustrate and explain certain principles of operation . a human patient 26 is supine on surface 14 . the length of the patient is along a horizontal longitudinal axis defined as the y - axis and the patient &# 39 ; s arms are spaced from each other along the x - axis . a c - arm 16 has portions 16 a and 18 b extending below and above table 10 , respectively , and is mounted in a suitable structure ( not shown expressly ) for moving at least parallel to the y - axis along the length of patient 26 . lower portion 16 a of the c - arm carries an x - ray source 20 that can emit x - rays limited by an aperture 22 into a fan - shaped distribution 24 conforming to a plane perpendicular to the y - axis . the energy range of the x - rays can be relatively wide , to allow for the known dxa dual - energy x - ray measurements , or can be filtered or generated in a narrower range to allow for single energy x - ray measurements . the x - ray distribution can be continuous within the angle thereof or can be made up , or considered to be made up , of individual narrower beams . the x - ray distribution 24 can encompass the entire width of the patient as illustrated , or it can have a narrower angle so the entire patient can be covered only by several passes along the y - axis and the x - ray measurements from the several passes can be combined as is known in the art to simulate the use of a wider fan beam , as typical in current commercial dxa systems . alternatively , a single , pencil - like beam of x - rays can be used to scan selected regions of the patient &# 39 ; s body , e . g . in a raster pattern . the x - rays impinge on x - ray detector 28 , which can comprise one or more linear arrays of individual x - ray elements 30 , each linear array extending in the x - direction , or a continuous detector where measurements for different positions along the detector can be defined in some manner known in the art , or can be another form of detector of x - rays . c - arm 16 can move at least along the y - axis , or can be maintained at any desired position along that axis . for any one position , or any one unit of incremental travel in the y - direction of arm 16 , detector 28 can produce one or several lines of raw x - ray data . each line can correspond to a row of pixels in a resulting image , which row extends in a direction corresponding to the x - direction . each line corresponds to a particular position , or range of positions , of the c - arm in its movement along the y - axis and / or a particular linear detector , and comprises a number of individual measurements , each for a respective detector element position in the line , i . e ., represents attenuation that the x - rays have suffered in traveling from source 20 to a respective detector element position over a specified time interval . a dxa system takes a higher x - ray energy measurement h and a lower x - ray energy measurement l from each detector element position , and carries out initial processing known in the art to derive , from the raw x - ray data , a set of pixel values for a projection image . each pixel value comprises a high energy value h and a low energy value l . this can be achieved by rapidly alternating the energy level of the x - rays from source 20 between a higher and a lower range of x - ray energies , for example by rapidly rotating or otherwise moving a suitable filter in or out of the x - rays before they reach patient 26 , or by controlling the x - ray tube output , and / or by using an x - ray detector 28 that can discriminate between energy ranges to produce h and l measurements for each pixel position , e . g ., by having a low energy and a high energy detector element side - by - side or on top of each other for respective positions in the detector array . the h and l x - ray measurements for the respective pixel positions are computer - processed as known in the art to derive estimates of various parameters , including , if desired , body composition ( total mass , fat mass , and lean mass ). nonlimiting examples of dxa systems include those described in u . s . patent application publication nos . 2011 / 0235886 and 2011 / 0311122 . fig2 illustrates spacing pads of such construction in use to space the arms of a patient from the torso . as the patient is prepared for the image scan , each pad is placed between an arm and trunk of the patient , as high up into the armpit of the patient as is comfortable . hands may be positioned vertically , but not against the hips to enable visualization of the arms cleanly cut from the trunk for analysis . although not illustrated , it is appreciated that a spacer pad may also be positioned between the legs of the patient . fig4 illustrates an exemplary scan which has been obtained using the spacing pads , and illustrating the clear delineation provided using the invention . fig3 illustrates an exemplary pad of the invention , encased for use in a sanitary , disposable plastic bag . such an arrangement enables the clear delineation of the individual body parts of a patient , allowing for more accurate mass determinations for various body parts and facilitating the comparison of different masses between related appendages . as a result , lymphedema may be more rapidly identified and a patient may receive treatment before appreciable progression of the chronic disease . it is to be appreciated that embodiments of the methods and apparatuses discussed herein are not limited in application to the details of construction and the arrangement of components set forth in the following description or illustrated in the accompanying drawings . the methods and apparatuses are capable of implementation in other embodiments and of being practiced or of being carried out in various ways . examples of specific implementations are provided herein for illustrative purposes only and are not intended to be limiting . in particular , acts , elements and features discussed in connection with any one or more embodiments are not intended to be excluded from a similar role in any other embodiment . also , the phraseology and terminology used herein is for the purpose of description and should not be regarded as limiting . any references to embodiments or elements or acts of the systems and methods herein referred to in the singular may also embrace embodiments including a plurality of these elements , and any references in plural to any embodiment or element or act herein may also embrace embodiments including only a single element . the use herein of “ including ,” “ comprising ,” “ having ,” “ containing ,” “ involving ,” and variations thereof is meant to encompass the items listed thereafter and equivalents thereof as well as additional items . references to “ or ” may be construed as inclusive so that any terms described using “ or ” may indicate any of a single , more than one , and all of the described terms . all parts , ratios , and percentages herein , in the detailed description and claims are by weight and all numerical limits are used with the normal degree of accuracy afforded by the art , unless otherwise specified . the dimensions and values disclosed herein are not to be understood as being strictly limited to the exact numerical values recited . instead , unless otherwise specified , each such dimension is intended to mean both the recited value and a functionally equivalent range surrounding that value . for example , a dimension disclosed as “ 40 mm ” is intended to mean “ about 40 mm ”. it should be understood that every maximum numerical limitation given throughout this specification includes every lower numerical limitation , as if such lower numerical limitations were expressly written herein . every minimum numerical limitation given throughout this specification includes every higher numerical limitation , as if such higher numerical limitations were expressly written herein . every numerical range given throughout this specification includes every narrower numerical range that falls within such broader numerical range , as if such narrower numerical ranges were all expressly written herein . all documents cited herein are , in the relevant part , incorporated herein by reference ; the citation of any document is not to be construed as an admission that it is prior art with respect to the present invention . to the extent that any meaning or definition of a term or in this written document conflicts with any meaning or definition in a document incorporated by reference , the meaning or definition assigned to the term in this written document shall govern . having described above several aspects of at least one embodiment , it is to be appreciated various alterations , modifications , and improvements will readily occur to those skilled in the art . such alterations , modifications , and improvements are intended to be part of this disclosure and are intended to be within the scope of the invention . accordingly , the foregoing description and drawings are by way of example only .
a system for detecting lymphedema comprising a dual energy x - ray absorptiometry system and one or more spacer pads disposed within a field of view of the dual energy x - ray absorptiometry system . the dual energy x - ray absorptiometry system comprises an x - ray source and a patient support platform , wherein the patient support platform is configured to receive a patient in a supine position with the x - ray source disposed above the patient support platform . the one or more spacer pads are configured to be positioned between body parts of the patient .