Radiation Oncology and Medical Devices ( Part 2)

Ning J. Yue, Ph.D., Professor,Ting Chen, Ph.D., Assistant Professor Wei Zou, Ph.D., Assistant Professor

Department of Radiation Oncology,Rutgers Cancer Institute of New Jersey,Rutgers University-Robert Wood Johnson Medical School

Radiation Oncology and Medical Devices ( Part 2)

Ning J. Yue, Ph.D., Professor,Ting Chen, Ph.D., Assistant Professor Wei Zou, Ph.D., Assistant Professor

Department of Radiation Oncology,Rutgers Cancer Institute of New Jersey,Rutgers University-Robert Wood Johnson Medical School

Radiation oncology is one of the three major treatment modalities to manage cancer patient cares, and is a discipline mainly driven by technology and medical devices. Modern radiation treatments have become fairly complex and involve in utilizing a variety of medical devices to achieve the goal of providing conformal radiation dose coverage to the tumor target(s) while maximizing the sparing of normal organ structures. Recently, different forms of linear accelerators/radioactive source based machines have been invented and developed with the aimof providing improved treatments and more treatment options. Besides linear accelerators (Linac) that have been undergoing constant improvement and advancement and can deliver fairly complicated dose distribution patterns, imaging systems, computer information and calculation systems have been more and more integrated into radiotherapy processes. To bring radiotherapy to a potentially higher level, many institutions have either acquired or started to consider particle therapy, especially proton therapy. The complexity of modern radiotherapy demands in-depth understanding of radiation physics and machine engineering as well as computer information systems. This paper is intended to provide an introductory description of radiation oncology and related procedures, and to provide an overviewof the current status of medical devices in radiotherapy in the United States of America. This paper covers the radiation delivery systems, imaging systems, treatment planning systems, record and verify systems, and QA systems.

radiation oncology; radiotherapy; external beamradiotherapy; Brachytherapy;intensity modulated radiotherapy; SRS; SBRT; Linac; treatment planning system; record and verify system;3DCRT; Simulator

4 Brachy therapy

Traditionally, brachytherapy are conducted exclusively with encapsulated radioactive sources. Radioactive sources decay by emitting various particles, and the rate of decay (activity, rate of disintegration) decreases with time in an exponential fashion.Although radioactive sources that emit electrons have also been used in brachytherapy, most of the brachytherapy sources are photon emitters of energies ranging fromlow20keV to over 1MeV. The half-lives of these sources range froma fewdays to over many years. The characteristics of some of the commonly used brachytherapy sources are listed in Table 1. Recently, an electronic brachytherapy system(Xoft, Inc., Sunnyvale, CA,USA) becomes available to radiation oncology communities. This systemrelies on a miniaturized x-ray tube to deliver radiation dose. Unlike radioactive sources that constantly emit radiation,the radiation source (the x-ray tube) in the electronic systemcan be turned on and off as needed.

Table I. Properties of a fewcommonly used encapsulated photon-emitting brachytherapy sources

One of the most important characteristics of a brachytherapy source is its dosimetric distribution. The dose distribution in a homogeneous water equivalent phantomcan be quantified bya fewparameters, such as source strength (air kerma strength), dose rate constant, geometry function, radial dose function, and anisotropy function, as defined in Reports 229[8],84[9], and51[10]of the American Association of Physicists in Medicine (AAPM). For radioactive sources that emit relatively lowenergy photons and electrons, these dosimetric parameters are sensitive to the source encapsulation and design, and are subject to change with different encapsulation and model design. Thus, brachytherapy sources made of identical radionuclide but of different designs or encapsulations can exhibit different dose distributions.For this reason, reports have been published to update the dosimetric information as newmodels of brachytherapy sources are introduced or existing models of brachytherapy sources are modified. AAPMand MD Anderson Radiological Physics Center of USA (RPC) have been maintaining a consensus brachytherapy source data registry (http://rpc.mdanderson.org/rpc/BrachySeeds/Source_Registry.htm) to ensure that only the brachytherapy source models of carefully examined dosimetric parameters be used in radiation treatments of patients. Similarly, the dosimetric parameters were also calculated, measured, and reported for the radiation source at several voltage settings of the Xoft electronic brachytherapy system[11].

Since patient tissues are inhomogeneous and often not water-equivalent, the adoption of the dosimetric parameters derived in homogenous water-equivalent phantomcan lead to inaccurate dose calculations for patient treatments. To address the deficiency, model based brachytherapy dose calculation methods have been developed, with the potentials to significantly improve the dose accuracy in clinical treatments. On the other hand, since most of the current clinical experiences have been acquired without the tissue inhomogeneity dose calculation correction, there are certain clinical implications one needs to take into consideration[12].

To minimize radiation exposure to health care providers,brachytherapy procedures are normally performed using after loading applicators. The applicators are first placed at desired locations and the radioactive sources are then loaded to deliver prescribed doses to the target volumes.

Brachytherapy treatments can be categorized based on type of insertion, length of treatment, and dose rate. In interstitial implants, radioactive sources are generally placed in multiple catheters inserted directly into the tumor bed; in intracavitary implants, radioactive sources are loaded in applicators placed inside a body cavity or cavity adjacent to the target volume;in intraluminal implants, source applicators are placed in the luman of a vessel, duct or airway; For lesions on patient surface,radioactive sources are placed in a mold or plaque and placed on the skin or mucosal surface for the treatment delivery.Brachytherapy procedures can be also categorized as temporary or permanent implants. Temporary implants usually lasts no more than a fewdays while permanent implants require that the sources remain inside the patient permanently. Permanent implants are practically only for interstitial treatments, and radioactive sources with relatively short half-lives are used so that the majority of the dose is delivered within a fewweeks or months. Permanent implants must employ sources with lowenergy emissions so that the dose rate at the patient's external surface is lowenough and it does not present significant risk of radiation exposure to others.Brachy implants can be further classified as high dose rate (HDR),mediumdose rate (MDR), or lowdose rate (LDR) treatments.HDR treatments deliver radiation to the target volume at a rate higher than 12Gy/hr; while LDR treatments deliver radiation in a rate between0.1(or0.2) Gy/hr and2Gy/hr, and the target dose rate in MDR treatments is between2Gy/hr and 12Gy/hr.

4.1 HDR

HDR brachytherapy treatment is almost always delivered using a remotely controlled after-loading system. The source delivery systemis controlled with a computer which is stationed outside a well shielded treatment room. Most of the HDR systems use a tiny192Ir source with an initial radioactivity of about 10Ci, although60Co source is also used in some HDR systems.The source is welded onto the end of a motor driven cable, and is housed in a shielded safe within the unit.192Irand60Co are preferred due to their high specific radioactivity. Recently, an electronic brachytherapy systemis commercially available and can be used to deliver HDR treatments.

There are three major manufacturers that provide HDR systems to the customers in the United States of America: Varian Medical Systems (Palo Alto, CA, USA), Nucletron - an Elekta Company (Stockholm, Sweden), and Xoft, Inc (Sunnyvale, CA,USA).

4.1.1 Varian Medical Systems

Currently, two models of HDR delivery systems are offered by Varian Medical Systems: VariSource iX and GammaMedplus iX afterloaders. Older models of the production lines are still being used in many clinics and are serviced by Varian Medical Systems.

The radioactive source in VariSource iX afterloader is made of two individual1922Ir sources of nominal strength5Ci.Each individual source is 2.5mmlong and0.35mmin diameter,resulting a total source strength of 10Ci and5mmin length. The two sources are encapsulated in a homogeneous nickel titaniumalloy, making the active source outer diameter about0.59mm.There are 20channels in the HDR unit (although the treatment delivery can be planned for40channels), and the source can be programmed for60dwell positions with a step size between 1and99mmin each of the channels for a dwell time ranging from0.10to999.99seconds per position and a maximumtime of50minutes per channel.

The Gamma Medplus iX series of afterloaders includes the GammaMedplus iX Systemand the GammaMedplus3/24iX system. The conventional GammaMedplus iX systemoffers 24channels and the GammaMedplus3/24iX systemoffers5channels. The combined length of the applicator and transfer tube is fixed at 1300mm. The systems provide a unique source transfer testing mechanism: the dummy source is sent to the end of the channel and then pressed for additional5mmto ensure that it detects the end of catheter for an unobstructed source path and a correct channel length. The last five channels in the GammaMedplus iX systemand last two of the GammaMedplus3/24iX systemare not tested by this mechanism. The radioactive source of the systems is4.52mmlong and0.9mmin outer diameter, and is fixed to a flexible metal cable driven by a motor system. There are60discrete dwell positions in each of the channels, with a step size from1to 10mm(in 1mmincrement).The dwell time at each dwell position can be from0.1to9999.9seconds. The systems can be used to deliver either HDR or Pulse Dose Rate (PDR) treatments.

BrachyVision, Acuros BV and Vitesse are the treatment planning systems offered by Varian Medical Systems for HDR treatments.

4.1.2 Nucletron - an Elekta Company

Nucletron provides a full range of products for HDR brachytherapy, including treatment planning system, delivery systems, and applicators. It offers two models of HDR delivery system: microSelectron Digital and Flexitron afterloading platform. With appropriate applicators, the systems can be used to treat many disease sites including head & neck, gynecology,prostate, bronchus & esophagus, skin & surface, rectum, breast,pancreas & bile duct. Both of the systems use1922Ir as their radiation source.

The micro Selectron®Digital afterloading system comes with options of6, 18or30channels. Its radioactive source size is about5mm long and 1.1mm in outer diameter. The source can be paused at dwell position intervals of 2.5,5or 10mm on the clinical preference, with a positioning accuracy of ± 1mm at each dwell position. It can be used to deliver either HDR or Pulsed Dose Rate (PDR) treatments.

The Flexitron afterloading systemis a newly designed HDR systemNucletron offers to radiation oncology communities. It can be configured with 10, 20or40channels. The source can be paused at dwell position interval of 1mmover a400mmwindowwith all of the transfer tubes of the same 1000mmlength. The source dwell positioning accuracy improves to0.5mm. The source strength can be as high as 22Ci.

Nucletron also manufactures an electronic brachytherapy HDR system(Esteya) that uses an x-ray source to treat skin cancer.

Oncentra Brachy Treatment Planning Systemis provided by Nucletron for planning HDR treatments.

4.1.3 Xoft,Inc - asubsidiary of iCAD, Inc

The Axxent Electronic Brachytherapy Systemproduced by Xoft, Inc is a HDR systemthat uses a miniaturized x-ray tube as its radiation source. The radiation source of this HDR systemcan be turned on and off electronically. The x-ray tube diameter is 2.25mmand 23mmin length. The energy level of the x-rays produced by the tube is about50kV and the nominal dose rate is about0.6Gy/min at3cmin water. The source voltage and current can be modulated, allowing flexible energy level and dose rate selection.

The electronic systemhas the advantage of reduced radiation safety concerns. However, its use may be limited by the relatively large source size and short source life time.

The commonly used HDR192Ir emits photons of relative high energies. Since the source constructions vary among different systems, careful dosimetric characterization is required for each different source design before it is put into clinical use.

4.2 LDR

137Cs,192Ir,125I,103Pdand131Cs radionuclides are commonly employed in LDR brachytherapy. In USA,192Ir,125I,103Pd and131Cs are normally available as individual seeds with the corresponding radionuclide absorbed onto substrate material and encapsulated with metallicmaterials. The typical seed size is4.5mmin length and0.8mmin outer diameter, although the values may vary fromone model to another.137Cs source is available as a tube with a much larger physical size (typically 20mmlong and3mmin outer diameter).

Since125I,103Pdand131Cs have relatively short half-lives and emit photons with relatively lowenergies, they are ideal for permanent brachy implants (e.g., permanent seed prostateimplants). On the other hand,137Csand192Ir have relatively long half-lives and emit high energy photons, they are almost always used for temporary LDR implants (e.g., breast and GYN implants).

In both HDR and LDR brachytherapy treatments,afterloading applicators play an extremely important role. They are normally designed and made to suit for treatments of certain disease sites to achieve optimal dose distribution. Their designs are likely vendor dependent and may not be interchangeable fromone vendor to another vendor.

5 Imaging and Immobilization Devices in Radiotherapy

5.1 Type of imaging device (2D,3D,MR,CT,signal based, etc)

The recent surge of image guided radiotherapy reflects the latest technology advances in imaging devices and the compatible imaging methodologies. Currently multimodality imaging protocols have been widely implemented in clinical practice for precise patient simulation and pre-treatment patient set up. In general, the devices can be classified into two categories: 2D imaging devices, and3D (or higher) image devices.

2D imaging devices currently used in radiotherapy include kV and MV x-ray imaging, fluoroscopy, angiography, and B-mode ultrasound. x-ray imaging is one of the conventional ways of detecting diseases in soft tissue and pathology of bony structures. As the x-ray beampenetrates the human body,its attenuation varies due to the physical density, electron density, and effective atomic number Z of different tissues (and diseases). x-ray imaging utilizes the variation to highlight the contrast between the targeted tissue and its surroundings. In radiation oncology, x-ray imaging can be conducted using either the conventional x-ray with energy in the kV range,or high energy x-ray in the MV range similar to the beamin radiotherapy. kV imaging usually has better tissue contrast than MV imaging. The MV based imaging, on the other hand,has less artifact to metal implants. Another advantage of MV imaging is that by sharing the same sources for imaging and radiation treatment, one can generate the beam-eye-view(BEV) to match the digitally reconstructed radiography (DRR) for accurate patient setup. Fluoroscopy is an X-ray based imaging technique that uses X-rays to obtain real-time moving images of the internal structures of a patient through the use of a fluoroscope. Angiography is a medical imaging technique used to visualize blood vessels and organs of the body, with particular interest in the arteries, veins and the heart chambers. This is traditionally done by injecting a contrast agent into the blood vessel and imaging using X-ray based techniques. B-mode ultrasound devices use the reflected signal of oscillated sound waves to detect the inner structure of human body. 2D ultrasound tomogramcan be generated using signals reflected fromdifferent depth (separated by time) with an array of sensors.

3D imaging devices currently used in radiotherapy include Computerized Tomography (CT), Magnetic Resonance Imaging (MRI), and other signal based imaging. CT technology uses computer processed penetrative X-ray signals to regenerate3D human body volumes with inner anatomies. In recent generation CT designs, a collimated x-ray source and an array of detectors are mounted at opposite positions on a rotational ring, with the presumed patient body in between. Based on the X-ray beamconfiguration, CT used in radiotherapy can be categorized into conventional CT and cone-beamCT (CBCT). During conventional CT scan, the patient supporting couch moves perpendicular to the imaging plane; and at any given time spot, the scanner is scanning a slab of the targeted patient body as the x-ray source and detectors continuously rotate around the patient body, generating x-ray attenuation projections at different angles which will be used to reconstruct human body tomography via filtered back projection algorithms. The size of the scanning slab is determined by the size of the x-ray detector, and the rows of detectors on the scanner. The x-ray source and detectors needs multiple rotations to collect adequate information to regenerate the3D patient body volume. Based on the way the couch moves corresponding to the x-ray source and detectors rotation, conventional scanning can be divided into Helical, Spiral, and Cine mode. acquisition,For CBCT acquisition, patient remains static during the data acquisition as a cone shaped broad x-ray penetrating the volume to be imaged. The CBCT x-ray source and detectors needs less than one complete rotation to regenerate the3D volume, but the maximal size of the volume is restricted by the overall size of the detectors. Respiratory motion information can also be captured using the CT technology using the respiration-correlated4DCT and4DCBCT approach. CT imaging causes extra radiation dose to the patient, which will increase the probability of the occurrence of cancer, especially for children. The evaluation and calculation of CT imaging dose to patient is comprehensively summarized in the AAPMreports[13,14]MRI images are used to visualize the human body internal anatomy. MRI makes use of the property of nuclear magnetic resonance (NMR) to imagenuclei of atoms inside the body. Radio frequency (RF) magnetic fields are used to systematically alter the alignment of nuclei (e.g.,proton in Hydrogen) to generate signals recorded and analyzed in the frequency domain (a.k.a., the k-space) using Fourier transformation.3D spatial information is visualized in this process with contrast between various tissues due to their difference in atomic composition. MRI does not cause extra radiation dose to the patient. However, it should be noted that patients with certain metallic implant and/or electronic devices are not eligible for MRI scanning. Please refer to the vendors before patient scanning to verify the MRI compatibility of implant. Positron emission tomography (PET) is a nuclear medical imaging technique that produces a three-dimensional image or picture of functional processes in the body. The commonly chosen biologically active molecule for PET in radiation oncology applications is F18-FDG, which indicates tissue metabolic activity by virtue of the regional glucose uptake, to explore the possibility of cancer metastasis. There are other RF signal based imaging devices such as the Calypso (visithttp://www.varian.com/us/oncology/imaging_solutions/calypsoformoreinformation), which continuously records real time spatial location of pre-implanted metallic fiducial markers, to help improving the precision and accuracy in radiotherapy. Ultrasound devices, when used together with calibrated location identification devices such as stepper, can also generate3D volume by merging spatial tagged 2D images.

5.2 Use of imaging devices in external beamradiotherapy

Imaging devices are used in external beamradiotherapy for two major purposes: ① simulation and treatment planning;and ② pre-treatment patient setup and infra-treatment patient motion monitoring for Image Guided Radiotherapy (IGRT). CT,with accurate HU calibration (HU/electron density, HU/relativestopping power) and radiation oncology compatible tabletop,is currently still the de facto choice for patient simulation and treatment planning in radiation oncology due to its relatively lowprice tag, minimal geometric distortion, and the correlation between the HU value and the electron density and relative stopping power of the tissue, which remains the fundamental for almost all commercially available dose calculation algorithms for photon and charged particle radiation. In addition, the DRRs generated fromCT volumes can be used for 2D image based patient setup. Latest CT models such as GE Discovery and Optima series, Siemens Somatomseries, Philips Brilliance series,implemented newtechnologies such as multi-rowdetectors,multi-sources scanning, lowdose scanning,4DCTcompatible,and etc., to achieve lower patient dose, less scanning time, finer image quality and higher resolution, and respiratory correlated tumor motion information. Varian Acuity (visithttp://www.varian.com/us/oncology/radiation_oncology/acuity/formoreinformation) is a standalone simulator which has the functionality of taking kV snapshot, fluoroscopy, and also3D CBCT images. It has been used for patient setup simulation. MRI has superior soft tissue contrast with no radiation dose, which makes it the ideal imaging modality for stereotactic radiosurgery, e.g., Gamma knife based brain SRS, simulation and treatment planning. Siemens,Philips, and GE MRI systems operating at0.35to3T provide high quality images for multiple sites in human body (for more information,visithttp://www.healthcare.siemens.com/magneticresonance-imaging,http://www.healthcare.philips.com/main/products/mri/,andhttp://www3.gehealthcare.com/en/Products/Categories/Magnetic_Resonance_Imaging). By choosing the appropriate RF pulse sequence, MRI can highlight specifictarget tissue and/or the contrast between the tissue of interest and background. After image registration, MRI and CTcan be used together to improve the accuracy and precision in radiation treatment planning: as the MRIprovides useful information about the location and extent of the tumor, and the CT-based treatment planning to optimize the conformity between tumor and dosedistribution, e.g., such as the usage of T1and T2MRI imagingin IMRT treatment planning for glioblastoma(http://www.rtog.org/ClinicalTrials/ProtocolTable/StudyDetails.aspx?study=0913).Co-registeredPET/CT(formoreinformation,visithttp://www3.gehealthcare.com/en/Products/Categories/PET-CT,http://www.healthcare.philips.com/us_en/clinicalspecialities/oncology/petct.wpd,andhttp://www.healthcare.siemens.com/molecular-imaging/pet-ctandPET/MRI(formoreinformation,visithttp://www.healthcare.siemens.com/magnetic-resonance-imaging/mr-petscanner,http://www3.gehealthcare.com/en/Products/Categories/PET-CT/PET_CT_and_MR_Trimodality_Imaging,andhttp://www.healthcare.philips.com/main/products/nuclearmedicine/products/ingenuity_tf_pet_mr/) are also widely used clinically to improve the accuracy of the tumor identification and localization by correlating the image contrast with regional biological metabolic activity. For emergency case, orthogonal kV x-ray imaging can also be used for a quick treatment planning for high energy photon-based radiotherapy. Also angiography has been used for Gamma knife treatment planning for Arterio-Venous Malformation (AVM) cases.

The pre-treatment patient setup imaging systemcan either be mounted on the treatment unit, or stand alone as a peripheral device. Onboard imaging system(OBI) has been adopted andmounted on many of newest clinical linear accelerators as a standard component, such as Varian Truebeamand Elekta Synergy systems, to provide capability of kV, MV, and CBCT imaging for 2D and3D patient setup. For lung tumor patients, kV x-ray based fluoroscopy has been used to verify the respiratorycorrelated tumor motion amplitude. Elekta Symmetry4DCBCT has also been used to regenerate corresponding3D volumes to verify the lung tumor against treatment plans. Accuray's Tomotherapy unit relies on the integrated MVCT (using the same x-ray source for treatment) for3D pretreatment patient setup.For ViewRay, a0.35T MRI has been integrated with a60Colbat treatment unit to provide real time MRI imaging for pretreatment setup and periodic patient position check. On the newly clinical SBRT systemVero, stereo kV x-ray sources mounted on the treatment annulus track the tumor motion in real time to control the delivery of treatment beam.

The Cyberknife systems use a peripheral imaging systemfor patient setup and motion monitoring: two stereo kV x-ray imaging modules (sources and detectors) are mounted to the treatment roomto provide continuous imaging to localize and track the motion of the tumor. Many newproton facilities have orthogonal kV x-ray imaging installed in the treatment roomto provide solution for patient setup in Image Guided Proton Therapy (IGPT). Calypso systemhas been used to monitor the3D tumor motion during the treatment for multiple disease sites including prostate. The detected motion of3(or more) noncoplanar implanted fiducials has been used to estimate the motion of the target volume. The treatment can be manually or automatically interfered when a pre-selected tolerance has been exceeded.

Optical imaging systems such as AlignRT system(visithttp://www.visionrt.comformoreinformation) have also been used in radiotherapy for the purpose of patient setup and motion detection.

It should be emphasized that the requirement and limitation of different imaging modalities must be clearly understood by the user for determination of imaging parameters, and for appropriate usage of acquired images. For example, when use certain imaging modality to identify or measure small structures, imaging parameters such as the slice thickness need to be carefully picked to achieve an optimal solution that balance the necessity to detect the target of interest at a fine resolution and the need to minimize the patient dose and imaging time. For another example, a valid HU to electron density calibration has to be conducted for each CT scanner to maintain the integrity and accuracy of the dose calculation for photon EBRT. Images acquired by not calibrated yet imaging devices cannot be used for tasks requiring calibration.Interchanging calibration among multiple imaging devices may cause serious clinical consequences such as over and/or under dose of the treatment target, and extraordinary toxicity to normal tissue.

5.3 Use of imaging devices in brachytherapy

Traditionally, orthogonal x-rays have been used to verify the applicator position and define the critical points of interest for GYN LDRs. The newimaging technology such as CT and CBCT gave physicians more options for image guided brachytherapy.CT and CBCT images have been used to generate volume-based HDR brachy plans for GYN, sarcoma, breast, prostate, and bronchus/esophagus diseases. Traditional CTs and simulators such as Varian Acuity can all be used in brachytherapy. CTcalibration is required for Monte-Carlo based brachytherapy dosimetry such as Varian Acuros (visithttp://www.varian.com/us/oncology/brachytherapy/acuros.htmlformoreinformation)． Recently,MRI hasbeenacceptedasacomplementary imaging modality in brachytherapy, especially for cervical cases, where high Z material of the applicator causes significant artifacts in CT images. For prostate cases (both permanent implant and HDR), transrectal ultrasound (TRUS) images have been used for pretreatment volume study, treatment guiding, and even online treatment planning (Varian Vitesee system, seehttp://www.varian.com/media/oncology/brachytherapy/pdf/Vitesse_Brochure.pdfformoreinformation). For brain related permanent radioactive source implant, MRI images are usually used for tumor localization and post-implant evaluation. PET/CT images are also used to detect metastasis tumor sites in brachytherapy. In certain interstitial brachytherapy such as Y90microsphere implant for liver tumor,fluoroscopy guidance is available through the dose delivery procedure.

Since afterloading applicators are frequently used in brachytherapy, imaging compatibility (image artifact and safety)between applicators and imaging devices needs to carefully examined to ensure high image quality and patient safety.

5.4 Immobilization Devices

There are two different kinds of immobilization devices:① is to immobilize the patient during simulation, setup, and treatment to improve the reproducibility of the patient setup,therefore to increase consistency of treatment delivery; ② is to monitor and suppress the internal motion of the tumor such as in the case of lung tumor.

Traditional immobilization systemsuch as the alpha-cradlemold has long been used in patient simulation and treatment.Currently, newsite specific immobilization devices such as thermoplastic frame masks, headrest, precise bite (for head and neck); breast boards and wing boards (for breast); belly board, base plate (for pelvic and hip); and vac-lock mold (whole body) have been applied in simulation and treatment. Special immobilization frames has been used for SRS (by Elekta-http://www.elekta.com/healthcare-professionals/products/elektaoncology/treatmenttechniques/positioning-and-immobilization.html,Civco-http://www.civco.com/ro/products/patient_immobilization,Best-http://www.arplay.com/product_pos.html,etc) and SBRT (e.g., the Abdominal Compress Board) to minimize the motion at the targeted volume for the radiosurgery. The SRS frames also help to establish the treatment coordinate systemto localize the target volume.

For the purpose to reducing internal target volume (ITV)in SBRT, respiratory restriction devices have been developed to reduce the amplitude of the respiration-correlated tumor motion.Voluntary breath hold system(visithttp://www.qfix.com/qfixproducts/sbrt-and-respiratory-gating.asp?CID=3&PLID=3formoreinformation) is another way to control the motion of lung tumor by allowing the patient to interactively control and hold their breath during simulation and radiation treatment.

6 Record and Verify Systems

Modern record and verify system(RVS) in radiotherapy not only verifies radiation treatment parameters thereafter records treatment results to reduce the risk of treatment errors but also serves as a centralized information management system. In addition to interfacing with treatment planning systems and treatment delivery systems, RVS may interface with imaging systems, other hospital medical record systems (e.g., pathology,lab, radiology), billing systems, etc. For the treatment parameter verification purpose, intended treatment parameters, such as beamtype, energy level, beamfield size, gantry angle and radiation output, are transferred to and saved in the RVS. Right before treatment, the parameters of treatment delivery systemare compared to the corresponding ones in the RVS and radiation is not delivered until the comparison is successfully completed and the parameters are verified. In many cases, RVS also feeds and controls the delivery systems for their delivery process,especially for sophisticated treatment modalities and methods (e.g., IMRT). Upon the treatment completion, the delivered machine and treatment parameters are recorded and saved in the RVS as treatment records. Beyond the primary roles as atreatment verification and record-keeping system, RVS has been expanded to include functionalities such as imaging analysis,activity schedule, data analysis, clinical assessment, care and medication documentation. With the expanded capabilities,some RVS become the preferred choice as an electronicmedical record (EMR) systemfor a radiation oncology facility. To a certain degree, RVS has become the core of a modern radiation oncology facility.

In the United States, there are two major RVSs: the ARIA Radiation Oncology Information System(Varian Medical Systems, Palo Alto, CA, USA) and MOSAIQ Radiation Oncology Information System( Elekta, Stockholm, Sweden). Both systems provide comprehensive solutions to information needs of a radiation oncology department. As a matter of fact, both systems can be expanded to provide information services to not only radiation oncology but also medical oncology and surgical oncology and act as complete oncology information management systems.

6.1 ARIA Radiation Oncology Information System

Health Level Seven (HL7) and DICOMstandard communication protocols are used in the ARIA systemto transfer data within and with other systems.

The ARIA Radiation Oncology Systemprovides (quoted fromVarian website:http://www.varian.com/us/oncology/radiation_oncology/aria/radiation_oncology.html)

6.1.1 Disease management

(1) ARIA automates cancer staging based on AJCC guidelines

(2) Manage toxicities according to disease site

(3) Access lab results, pharmacy/drug orders, and full medical oncology information if sharing ARIA medical oncology information database

6.1.2 RT treatment plan review

Prescribe treatments, create and edit plans, track dose,and reviewreference images using ARIA's treatment plan management functionality.

(1) Accelerate intent and prescription entry using customizable templates

(2) Access plans created in Eclipse treatment planning software with no import/export steps

(3) Import plan data fromany DICOM-compliant treatment planning system

6.1.3 Image review

Guide treatment decisions real time digital images. ARIAsupports a wide range of multi-modality images including MV,kV, conventional CT, CBCT, MR and PET in support of imageguided oncology program.

(1) Reviewimages remotely and send setup instructions to the treatment machine

(2) Reviewdosimetric images for IMRT pre-treatment quality assurance

(3) Compare images using automatic, manual or fiducial marker matching algorithms

6.1.4 Health assessment

Record, monitor and evaluate patient health throughout the course of treatment and design a personalized care plan that addresses the unique needs of each patient.

(1) Record results of reviewof systemand physical examusing ARIA's automatictranscription tool

(2) Graph changes in patient's vital signs and lab results to identify trends

(3) Create customizable data collection forms and questionnaires

6.1.5 RTchart auditing

Performregular chart audits to oversee each patient'streatment course.

(1) Quickly identify plan changes and treatment overrides using color-coded cues

(2) Create a reliable audit trail with electronic signature with date stamp

(3) Authorize QA completion with a single mouse click

6.1.6 Electronic documentation

ARIA can help create a fully electronic, "paperless"department. Use ARIA to document clinical activities to support evidence-based and pay-for-performance initiatives.

(1) Create customizable electronic forms to replace hard copy documentation

(2) Provide an audit trial of document approvals using electronic signoff with date/time stamps

(3) Attach images, files or patient photographs to documents

6.1.7 Scheduling

Manage staff, patient, and resource schedules with userfriendly appointment and task management system.

(1) Create recurring appointments and instantly identify any scheduling conflicts

(2) Create task lists to organize workload and standardize care

(3) Synchronize your work schedule in ARIA with Microsoft Outlook ™ calendar

6.1.8 Charge posting

Record all procedures and activities performed at the point of care to ensure accurate charge posting. ARIA records all completed activities to enable charge and relative value unit (RVU) export, process tracking and productivity analysis.

(1) Split technical and professional charges

(2) Refine charges using relative value units (RVUs),procedure codes and multiple modifiers

(3) Export charges to your choice of HL7-compliant billing software

6.1.9 Information/Image Transfer

Streamline department workflowby electronically exchanging patient data and images with other healthcare departments including pathology, radiology, pharmacy, lab and billing.

(1) Specify real-time or schedule-driven update intervals

(2) Use standard HL7interfaces or create custominterfaces as required

(3) Customize data filters to specify the types of information exchanged

6.1.10 Data archiving

Manage the growing volume of clinical data by periodically archiving patient records and images.

(1) Save data to local hard drives, online storage devices,CD/DVD or DICOM-compliant PACS

(2) Update demographic and scheduling information as required

(3) Store data in DICOMand XML format to guarantee future access

6.2 MOSAIQ Radiation Oncology Information System

The MOSAIQ Radiation Oncology Systemprovides (quoted fromElekta website:http://www.elekta.com/healthcareprofessionals/products/elekta-software/radiation-oncology.html):

6.2.1 MOSAIQ Workflowand Charting

(1) Connectivity with hospital information, diagnostic, billing and other third-party systems

(2) Integrated Practice Management including centralized department scheduling for optimal efficiency

(3) User-defined workspace and configurable screen views

(4) Extensive documentation tools

(5) Quality checklists and patient assessments

(6) Manual, barcode and biometric patient identification and verification options provide multilevel safety checkpoints

6.2.2 Treatment Planning

(1) Setup details, immobilization devices and referencemages entered into treatment chart

(2) Seamless connectivity of treatment planning data fromthe electronic patient record to the accelerator

(3) Treatment planning data is held in MOSAIQ and monitored throughout the treatment delivery, with no need to switch screens

(4) Long termimage/data storage in MOSAIQ Data Director can be accessed throughout the treatment process

(5) Integrate with virtually any treatment planning or linear accelerator

6.2.3 Image Management

(1) Sophisticated image visualization and distribution

(2) 3D viewers: RTP, XVI, and iViewGT ™ integration,adding and synchronizing tools, 2D image registration, volume image viewing

(3) External image registration, MOSAIQ Setup Intelligence

(4) Stereoscopic and volume image registration

(5) Trend analysis and treatment setup workflowmanagement

6.2.4 Patient Verification and Delivery

(1) Patient and treatment site verification

(2) Multiple patient verification tools

(3) Supports all pre-treatment checks including patient positioning, treatment accessory verification and daily and cumulative dose

(4) MOSAIQ verifies accelerator settings and records treatment delivery data and images in the patient record

(5) Connects to major treatment delivery vendors

6.2.5 Treatment Summary and FollowUp

(1) Oncology-specific code capture and complete billing systemfor fast, accurate reimbursement

(2) Treatment summary reporting to hospital information management systems and referring doctors

(3) Submission management to hospital and regional authorities

(4) Interface to local and regional cancer registry recording

(5) Reporting tools fromCrystal Reports and documentation including eScribe for importing merge fields into letters and documents

(6) Survivorship facility to link cancer survivors to their care teams

6.2.6 Evidence-based Medicine

(1) Enhanced data interrogation and trending to measure performance, quality of care and patient outcomes

(2) Access to NCCN guidelines for best practice treatment guidance fromwithin the patient record with no need to switch screens

(3) Coherent reporting across practice/financial/clinical departments

6.2.7 Delivering long termcare and followup for cancer survivors

The MOSAIQ Survivorship module creates a patientspecifictreatment summary with recommendations for followup based on the patient's cancer type. A complete viewof diagnosis, treatment delivered, contact information for key staff and a calendar for specifictests recommended over several years can be compiled and customized by the care provider for each patient. The Survivorship summary also provides cancer-specific patient education material and resources for maintaining health and well-being, such as cancer foundations, support groups and exercise classes available in the patient's local community.The care provider can select to adjust the type and quantity of material that is provided to the patient. This flexible module can be delivered to the patient and to the referring physicians by print, secure email, a password-protected jump drive or within a patient portal.

7 Quality Assurance Devices

A solid and comprehensive quality assurance (QA) programis extremely critical to the high quality of patient care in a radiation oncology department[15-24].As described in the previous sections, there can be multiple types of machine systems coexistent in a radiation oncology program, and different type of machine systemmay require different type of QA devices (visithttp://www.sunnuclear.com/home.asp,http://www.ptw.de/radiation_therapy.html,http://www.standardimaging.com/,http://www.iba-dosimetry.com/formoredetailedinformation). Although these QA devices are usually not directly used in patient care,they are extremely important and indispensable to the QA programs.

In summary, radiotherapy process becomes more and more sophisticated and are involved a variety of advanced medical devices. Most of these medical devices are computerized and require careful evaluation of their functionalities and features.The proper operation and maintenance of the medical devices demands the personnel to undergo rigorous and dedicated trainings beforehand and demands the establishment and implementation of comprehensive QA programs. Care should be taken to ensure compatibility and interchangeability among the devices themselves and with other systems in the institution,especially with imaging and information systems. It is foreseeablethat the radiotherapy medical devices will become more and more integrated in terms of functionality and information transfer and will be able to provide more accurate and precise radiation treatment tools to further improve cancer patient care.

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R197.39；TH774

B

1674-1633(2014)02-0001-10

10.3969/j.issn.1674-1633.2014.02.001

Received November5, 2013; Revision received December3, 2013

Address correspondence to N.J.Y. (e-mail: yuenj@cinj.rutgers.edu).