Research about Process Archive of Computerized Surgery Navigation Based on PACS

Joumal of Donghua University (Eng. Ed.) Vol. 25, No.5 (2008) 495Research about Process Archive of Computerized Surgery NavigationBased on PACSDENG Hong(邓宏)" , CHEN Li(陈笠), CHEN Xiao-jun (陈晓军), WANG Cheng-tao (王成焘)Institute of Mechanical and Pouer Engineering , Shanghai Jiaotong University, Shanghai 20030, ChinaAbstract: Since the process of the surgery navigation isand the relative position relationship between the surgicalan operation-sensitive process, it is important to recordscalpel and the surgery region; secondly, because theand archive the whole process. In this paper, some keyrefresh frequency of the video recording device is lowertechnologies are introduced to accomplish processthan that one of the display of the navigation system, it isarchive of computerized surgery navigation based on theimpossible to reproduce the real condition of thepicture archiving and communication system( PACS).navigation system and surgeon's operations in real time;Firstly, the images and track data are acquired by thefinally, since the video recording files can't be supportedscreen captured tool and the navigation software.by PACS or the hospital information system ( HIS),Secondly, these image and data files are converted tosurgeons aren't able to access PACS or HIS in bospital tothe digital imaging and communications in medicineread such files for evaluation.(DICOM) files supported by PACS and transferred intoAccording to the above deficiency and defect, somethe database in PACS. The process of surgerytechnologies for process archive are introduced in thisnavigation is recorded and archived. Finally， theoriginal data of process archive is acquired from PACS,paper. Firstly， by interfacing with the navigationand this data is used to play back and restore thesystem，the data acquisition module collects images andprocess of surgery navigation.position coordinate data from the procedure of surgeryKey words: process archive; computerized surgerynavigation in real time; secondly， these images andnarigatiom; PACS; process playback; process restoreordinate data are converted to the corresponding DICOMCLC umber: TP 391Document code: Afiles which can be supported by PACS in hospitals andArticle D: 1672 - 5220(2008)05 - 0495 - 0then transferred to PACS; finally， after finishingrecording the procedure of surgery navigation， thisprocedure can be replayed and restored according to theIntroductionabove images and ordinate data. The procedure ofsurgery navigation can be evaluated qualitatively anThe technology of computerized surgery navigation isquantitatively based on process archive of surgeryutilized to provide instructions for surgery operation tonavigation.surgeons and can be used to aid those surgeons who areshort of practical surgical experience to accomplish their1 The Flow of Process Archive and Its Keysurgeries and aid common surgeons to finish complicatedTechnologiessurgeries that require high precisionlr.However,during the course of surgery navigation, although surgery1.1 The flow of process archivenavigation system can be utilized to guide surgeonsThere are two stages in the flow of process archive.continuously, there is possibility for surgeons to takeThe first stage is to collect data from the procedure ofwrong operations to cause injury to the patient and lead tothe failure of the surgery. Therefore, it is of criticalsurgery navigation by using relevant hardware andclinical importance to record the whole surgery process insoftware of navigation system in real time, then thesereal time for evaluation of surgery process and failuredata are to be converted to the DICOM file anddiagnose in the future. The general method to recordsubsequently transferred to the PACS system. The secondsurgery process is video capture. This recording methodstage is to pick up the archived data from the PACSof surgery process has some deficiency and defect assystem and the procedure of surgery navigation is to befollows: firstly, video recording can't be used to preciselyreplayed and restored based on these data. The flow isdescribe the real movement track of the surgical sealpelillustr中国煤化工YHCNMHGReceived date: 2007-09 - 13* Correspondence should be addressed to DENG Hong, E-mail; denghongdh@126. com496Joumal of Donghua University (Eng. Ed.) Vol.25, No. 5 (2008)surgery navigation. These acquired images are to be siavedData acquisitionin time order. At the stage of surgery simulation, theData conversionacquired position coordinate data is the coordinate data ofProccss play backthe simulated osteotomy path. At the stage of real surgeryand process restoreData storagenavigation, the position coordinates of the movement trackof the surgical scalpel are acquired by the orientator in theData extractionsurgery navigation system according to the predefinedacquisition frequency. Such coordinate data is to be savedFig. 1 The flow of process archivein real time.1.2 The data acquisition1. 2.3 The outcome of the data acqulsition1.2. 1 The method for the data acquisitionDuring the whole procedure of surgery navigation, a .In order to accomplish process archive for surgeryseries of images and a TXT file of position coordinate datanavigation, the critical data which can be used to reflectare to be acquired. These images are used to ilustratethe whole process needs to be acquired. The navigationsituations of surgery navigation operation and the TXT filedisplay is the main part of the surgery navigation systemis utilized to record all of coordinate data in the surgeryand the situation about the patient and the surgical scalpelnavigation procedure. To ensure that such images can beis displayed on the screen. By capturing screens on themanaged in correct order, the acquisition time of eachdisplay and saving as the corresponding images, the wholeimage is involved in the name of such image file. The namesurgery navigation process can be recorded vividly. Byof each image file consists of the patient's ID and thecomparing the real movement track of the surgical scalpelacquisition time of such image.and the simulated osteotomy path, the surgery operations1.3 The data conversion and storagecan be assessed. The position coordinate data of the real1.3.1 The data format of DICOMmovement track of the surgical scalpel is the basis of theA DICOM file consists of a file head and a DICOMasessment and can be acquired by the orientator in thedata set. The corresponding information which is used tosurgery navigation system.identify the data set is included in the file head. The dataThe data acquisition involves image data and positionset also includes other image-related information ascoordinate data. The image data is to be saved in a series offollows: patient's name, birth date, inspect date, patient'sBMP files and all of the position coordinate data is to beID，etc. Such information consists of brief charactersaved in a TXT file only.information and numeric information. The data set consists1.2.2 The frequency of the data acquisitionof several data elements and there are four parts in eachThe frequency of data acquisition is involved in thedata element as follows: tag, data description, data lengthfrequency of image and position coordinate dataand data value. .acquisition. The frequency of image acquisition refers to1.3.2 The data conversionthe times that the image acquisition module captures screen(1) The principle and the flow of conversion from theof the navigation display in a minute. Similarly, theBMP file to the DICOM filefrequency of position coordinate data acquisition is definedBecause the common images (such as BMP, JPEG)as the times that the orientator acquires the positionare short of some information, such as patient's personalcoordinates of the surgical scalpel in a minute. In general,information, examinationinformation and seriessince higher acquisition frequency means more images to beinformation, it is difficult for surgeons to understand theacquired, the precision of process archive is improved whenparticular conditions by use of such images. However,a high acquisition frequency is applied. However, if therethe DICOM file does not only include basic medicalare too many images to be acquired, the work load of theinformation of the patient, but also contains abovesurgery navigation system is to be increased obviously.involved information. It is helpful for surgeons to use theTherefore, it is necessary to set the frequency of imageDICOM files to make a diagnosis correctly.acquisition reasonably to ensure the balance between theFurthermore, the common images can be transferred toprecision and the work louad.the PACS server and saved it in after these images areThere are two stages in the acquisition of images andconverted to the DICOM files, and surgeons can pickposition coordinate data: the surgery simulation stage andthem up from PACS Server to read easily to make andthe real surgery navigation stage. When acquiring images,verify中国煤化工d format of imagescreens of display of the surgery navigation system are to becaptured in real time according to the preset capturingileiYHCN M H Giow of coversionfrequency at the stages of surgery simulation and realfrom the BMP format to the DICOM format isJoumal of Donghua University (Eng. Ed.) Vol. 25, No. 5 (2008) 497ilustrated in Fig. 2.The TXT format is used by the data files that contain aseries of position coordinate data for surgery navigationInformationBMP fileprocess. When these TXT files are to be converted to thedatabaseDICOM files, all of data in the TXT files are witten intoData extractiondata elements corresponding to the DICOM data set. EachNon- pixel↓Pixel dataposition coordinate data consists of three coordinatedataelements: X, Y and Z. This data is written into the valuePixel pocessingTo constructfield of the data element in the DICOM data set todata tobeconstruct a DICOM data element, and the data structure ofTo construct pixelDICOMi data tobe..the DICOM file is ilstrated in Fig. 3. .elementsDICOM elementsData seTag sequenceTo create| Data element'Data elementDICOM fileFig. 2 The flow of converting the BMP file to the DICOM fileValue Value●The pixel extractionTag No.| expression lengthValue fieldFirstly, the non-pixel information is extracted fromthe BMP file to constitute the non-pixel data element of theL - - . Field alternative: TransmissionDICOM file; subsequently, the pixel data information isformat ~ dependantextracted from the BMP file and the necessary pixel processingFig. 3 The data format of the DICOM fileoperation should be made before transforming such pixel data1.3.3 The data storageinto the pixel data element of the DIOOM file.By the file conversion operation, the acquired data of) The pixel processingprocess archive is converted to the data of DICOM format.Step1 The arrangement order of pixels should beSo these converted DICOM data can be transferred into theadjusted, because such order in the BMP file is opposite todatabase of the archive server in PACS environment withthat one in the DICOM file.the transport protocols of DICOM.Step2 If the number of byte of pixel data in the row1.4 The data extractionof the BMP file's data structure can't be divided by 4The data extraction is to obtain DICOM files fromexactly, the pixel data should be remedied in byte. ThePACS for surgery navigation process and convert thesecalculation formula[8] is shown as follows;DICOM files to BMP files and TXT files correspondinglyLineSize= (Width x bitCount+ 31)32X4for process playback and restore. The conversion fromStep3 During the treatment of grey scale for colorDICOM file to BMP or TXT file is opposite to that oneimages, the below empirical formulal] is used to calculatefrom BMP or TXT file to DICOM file.Since the purpose of the data extraction is to obtainthe value of grey scale corresponding to RGB pixels:necessary data for process playback and restore, it isGray=0. 299XR +0. 587XG +0.114XBnecessary to pay attention to the order control during theWhen constructing each DICOM file, some importantprocedure of data extraction. The order control is to keepinformation should be flled in as follows; ( 0X0028,the obtained DICOM files in time order to ensure that the0X0002) Samples Per Pixel， ( 0X0028，0X0004 )process playback is in the same time order as the surgeryPhotometric Interpretation, ( 0X0028，0X0100) Bitsnavigation process. The order control is only necessary forAllocated, (0X0028, 0X0101) Bits Stored and (0X0028,obtaining DICOM files from PACS that are originated from0X0102) High Bit'9.BMP files and conversion from DICOM files to BMP files,, The file conversionbecause there are a number of DICOM files for eachAfter pixels have been processed, the DICOM elementsurgery navigation process.is to be constituted with above data, and then the DICOM1.5 The prcess playback and the process restorefile is to be created. At that time, the conversion of file is1.5.1中国煤化工series of imagesaccomplished.. navigation, a series(2) The principle and the flow of conversion from theof arcMYHCNMHGuoulyinrealtimedata file to the DICOM fileorder. The process playback of surgery navigation for oral498Joumal of Donghua University (Eng. Ed.) Vol. 25, No. 5 (2008)implant is ilustrated in Fig.4.39.2140 1360.0138N06s.14142.88.04387.0Fig. 6 The real movement track of the surgical scalpelFig 4 The poces playback of surgery narigation for oral implant1.5.4 The relation between the process playback and the1.5.2 The process restore based on a series of coordinateprocess restoredata of positionThe corresponding relationship should be createdTo accomplish the process restore based on thebetween the process playback based on images and thecoordinate data， three steps should be takenprocess restore based on coordinate data. By identifyingsequentially. Firstly, the real movement track of thsurgical scalpel is fit on the base of previously extractedthe corresponding relationship, the difference between thecoordinate data of position; secondly, the standardreal surgery process and the simulated surgery process canmovement track of the surgical scalpel is fit according tobe found out to be the basis for the surgery navigationthe coordinate data from surgery simulation; finally,assessment.the difference is attained by comparing the real1.5.5 Application of process archive for computerizedsurgery navigationmovement track and the standard movement track forThe process archive technology is applied in the imagefurther evaluation.1.5.3 The demonstration for the track of the surgical scalpelguided oral implantology system ( IGOIS)，which isThe restore of the simulated movement track of thesupported by Shanghai Science and Technology Committee.surgical scalpel ( the simulated osteotomy path); theAllof the data in Figs. 4-6 is obtained by the processsimulated movement track of the surgical scalpel can bearchive technology from IGOIS. By using of processdemonstrated by using the visualization module in Originarchive, the whole process of oral implantology surgeryand the previously archived data for the simulated surgerynavigation can be recorded and used for subsequent surgerynavigation process from PACS is used to support thedemonstration. The restore result of the simulated surgerynavigation process for oral implant is ilustrated in Fig. 5.2 ConclusionWith the development and improvement of the2+computerized surgery navigation technology， more and40-more surgery navigation systems are to be applied inclinical surgeries. So it is urgent to make a record and381archive for the process of surgery navigation. In this36-paper, according to the characteristics of computerized34surgery navigation process, the technology of process32- s全91.0archive of surgery navigation based on PACS is proposed139 140” 1489.0and all of the relevant key technologies are analyzed in42detail. These key technologies are data acquisition, dataconversion and storage. data extraction, process playbackFig. 5 The simulated movement track of the surgial scalpeland restore. By use of process archive, the whole processThe restore of the real movement track of the surgicalof surgery navigation can be recorded and saved in PACSscalpel: the restore method is identical with the restorebase中国煤化工ived process data.method of the simulated movement track. The restoreUltim三be used to provideresult of the real movement track of the surgical scalpel isimpcMYHC N M H Ggery ealuation andilustrated in Fig. 6.follow-up surgery.Joumal of Donghua University (Eng. Ed.) Vol. 25, No.5 (2008) 499Programs in Biomedicine, 2002, 69: 211- 224.References[5] Jjing Yang， Matthew O Ward, Elke A Rundenstciner.Interactive Hierarchical Displays: a Ceneral Framework for[1] Ozawa N, Muragaki Y, Shirakawa H, et al. 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