Radiation Oncology Treatment Planning Research Articles

Evaluation of a commercial automatic treatment planning system for prostate cancers

Recent developments in Radiation Oncology treatment planning have led to the development of software packages that facilitate automated intensity-modulated radiation therapy (IMRT) and volumetric-modulated arc therapy (VMAT) planning. Such solutions include site-specific modules, plan library methods, and algorithm-based methods. In this study, the plan quality for prostate cancer generated by the Auto-Planning module of the Pinnacle3 radiation therapy treatment planning system (v9.10, Fitchburg, WI) is retrospectively evaluated. The Auto-Planning module of Pinnacle3 uses a progressive optimization algorithm. Twenty-three prostate cancer cases, which had previously been planned and treated without lymph node irradiation, were replanned using the Auto-Planning module. Dose distributions were statistically compared with those of manual planning by the paired t-test at 5% significance level. Auto-Planning was performed without any manual intervention. Planning target volume (PTV) dose and dose to rectum were comparable between Auto-Planning and manual planning. The former, however, significantly reduced the dose to the bladder and femurs. Regression analysis was performed to examine the correlation between volume overlap between bladder and PTV divided by the total bladder volume and resultant V70. The findings showed that manual planning typically exhibits a logistic way for dose constraint, whereas Auto-Planning shows a more linear tendency. By calculating the Akaike information criterion (AIC) to validate the statistical model, a reduction of interoperator variation in Auto-Planning was shown. We showed that, for prostate cancer, the Auto-Planning module provided plans that are better than or comparable with those of manual planning. By comparing our results with those previously reported for head and neck cancer treatment, we recommend the homogeneous plan quality generated by the Auto-Planning module, which exhibits less dependence on anatomic complexity.

What should we know about photon dose calculation algorithms used for radiotherapy? Their impact on dose distribution and medical decisions based on TCP/NTCP

The dose calculation algorithms, integrated in a radiotherapy treatment planning system, use different approximations to swiftly compute the dose distributions. Any biological effect is somehow related to the dose delivered to the tissues. Thus, the optimization of treatment planning in radiation oncology requires, as a basis, the most accurate dose calculation to carry out the best possible prediction of the Normal Tissue Complication Probability (NTCP), as well as Tumor Control Probability (TCP). Presently, a number of bio-mathematical models exist to estimate TCP and NTCP from a physical calculated dose using the differential dose volume histogram (dDVH). The purpose of this review is to highlight the link between any change of algorithms and possible significant changes of DVH metrics, TCP, NTCP and even more of estimated Quality-adjusted life years (QALY) based on predicted NTCP. The former algorithms, such as pencil beam convolution (PBC) algorithm with 1D or 3D density correction methods, overestimated the TCP while underestimating NTCP for lung cancer. The magnitude of error depends on the algorithms, the radiobiological models and their assumed radiobiological parameters setting. The over/under estimation of radiotherapy outcomes can reach up to 50% relatively. Presently, the anisotropic analytical algorithm (AAA), collapsed cone convolution algorithm (CCC), Acuros-XB or Monte Carlo are the most recommended algorithms to consistently estimate the TCP/ NTCP outcomes and QALY score, to rank and compare radiotherapy plans, to make a useful medical decision regarding the best plan. This paper points out also that the values of the NTCP radiobiological parameters should be adjusted to each dose calculation algorithm to provide the most accurate estimates.

Issues in accurate PET for target delineation in radiotherapy

Tumor delineation in PET imaging has been one of the main concerns for treatment planning in radiation oncology. However, a standardized way of converting PET signals into target volumes is not yet available. The majority of the literature on delineation methods deals with 18FDG-PET imaging. In this context, semiautomatic and automatic segmentation methods have been developed implying gradient, region growing, clustering, statistical methods, but the majority of these new algorithms are not widely and readily available. Adaptive thresholding methods based on contrast-oriented contouring algorithms have been developed by many groups and validated in patient data for different anatomical regions. Among their strong points easiness of use and low cost must be accounted for, while among the drawbacks heterogeneity in lesion uptake and lesion motion are still open questions. Moreover, quantification and delineation issues become even more troublesome when partial volume effect is considered and corrected for by applying resolution modeling techniques. Literature shows lack of evidence ensuring that resolution modeling algorithms can provide accurate and reproducible data, suggesting that resolution modeling reconstruction algorithms in quantitative 18FDG-PET imaging need to be accurately validated before introduction in clinical routine. Other issues in tumor delineation are concerned with PET imaging performed with radiotracers different from 18FDG, for example 11C-choline and 11C-methionine for prostate and brain tumors imaging, for which the conclusions drawn for 18FDG imaging delineation may not apply and different techniques and strategies must be looked for.

The American Society for Radiation Oncology's 2015 Core Physics Curriculum for Radiation Oncology Residents

The American Society for Radiation Oncology (ASTRO) Physics Core Curriculum Subcommittee (PCCSC) has updated the recommended physics curriculum for radiation oncology resident education to improve consistency in teaching, intensity, and subject matter. The ASTRO PCCSC is composed of physicists and physicians involved in radiation oncology residency education. The PCCSC updated existing sections within the curriculum, created new sections, and attempted to provide additional clinical context to the curricular material through creation of practical clinical experiences. Finally, we reviewed the American Board of Radiology (ABR) blueprint of examination topics for correlation with this curriculum. The new curriculum represents 56hours of resident physics didactic education, including a 4-hour initial orientation. The committee recommends completion of this curriculum at least twice to assure both timely presentation of material and re-emphasis after clinical experience. In addition, practical clinical physics and treatment planning modules were created as a supplement to the didactic training. Major changes to the curriculum include addition of Fundamental Physics, Stereotactic Radiosurgery/Stereotactic Body Radiation Therapy, and Safety and Incidents sections, and elimination of the Radiopharmaceutical Physics and Dosimetry and Hyperthermia sections. Simulation and Treatment Verification and optional Research and Development in Radiation Oncology sections were also added. A feedback loop was established with the ABR to help assure that the physics component of the ABR radiation oncology initial certification examination remains consistent with this curriculum. The ASTRO physics core curriculum for radiation oncology residents has been updated in an effort to identify the most important physics topics for preparing residents for careers in radiation oncology, to reflect changes in technology and practice since the publication of previous recommended curricula, and to provide practical training modules in clinical radiation oncology physics and treatment planning. The PCCSC is committed to keeping the curriculum current and consistent with the ABR examination blueprint.

Automated segmentation of the thyroid gland on thoracic CT scans by multiatlas label fusion and random forest classification.

The thyroid is an endocrine gland that regulates metabolism. Thyroid image analysis plays an important role in both diagnostic radiology and radiation oncology treatment planning. Low tissue contrast of the thyroid relative to surrounding anatomic structures makes manual segmentation of this organ challenging. This work proposes a fully automated system for thyroid segmentation on CT imaging. Following initial thyroid segmentation with multiatlas joint label fusion, a random forest (RF) algorithm was applied. Multiatlas label fusion transfers labels from labeled atlases and warps them to target images using deformable registration. A consensus atlas solution was formed based on optimal weighting of atlases and similarity to a given target image. Following the initial segmentation, a trained RF classifier employed voxel scanning to assign class-conditional probabilities to the voxels in the target image. Thyroid voxels were categorized with positive labels and nonthyroid voxels were categorized with negative labels. Our method was evaluated on CT scans from 66 patients, 6 of which served as atlases for multiatlas label fusion. The system with independent multiatlas label fusion method and RF classifier achieved average dice similarity coefficients of [Formula: see text] and [Formula: see text], respectively. The system with sequential multiatlas label fusion followed by RF correction increased the dice similarity coefficient to [Formula: see text] and improved the segmentation accuracy.

SU‐E‐J‐192: Verification of 4D‐MRI Internal Target Volume Using Cine MRI

Purpose:To investigate the accuracy of 4D‐MRI in determining the Internal Target Volume (ITV) used in radiation oncology treatment planning of liver cancers. Cine MRI is used as the standard baseline in establishing the feasibility and accuracy of 4D‐MRI tumor motion within the liver.Methods:IRB approval was obtained for this retrospective study. Analysis was performed on MR images from four patients receiving external beam radiation therapy for liver cancer at our institution. Eligible patients received both Cine and 4D‐MRI scans before treatment. Cine images were acquired sagittally in real time at a slice bisecting the tumor, while 4D images were acquired volumetrically. Cine MR DICOM headers were manipulated such that each respiratory frame was assigned a unique slice location. This approach permitted the treatment planning system (Eclipse, Varian Medical Systems) to recognize a complete respiratory cycle as a “volume”, where the gross tumor was contoured temporally. Software was developed to calculate the union of all frame contours in the structure set, resulting in the corresponding plane of the ITV projecting through the middle of the tumor, defined as the Internal Target Area (ITA). This was repeated for 4D‐MRI, at the corresponding slice location, allowing a direct comparison of ITAs obtained from each modality.Results:Four patients have been analyzed. ITAs contoured from 4D‐MRI correlate with contours from Cine MRI. The mean error of 4D values relative to Cine values is 7.67 +/− 2.55 %. No single ITA contoured from 4D‐MRI demonstrated more than 10.5 % error compared to its Cine MRI counterpart.Conclusion:Motion management is a significant aspect of treatment planning within dynamic environments such as the liver, where diaphragmatic and cardiac activity influence plan accuracy. This small pilot study suggests that 4D‐MRI based ITA measurements agree with Cine MRI based measurements, an important step towards clinical implementation.NIH 1R21CA165384‐01A1

Investigation of a method for generating synthetic CT models from MRI scans of the head and neck for radiation therapy

Magnetic resonance (MR) images often provide superior anatomic and functional information over computed tomography (CT) images, but generally are not used alone without CT images for radiotherapy treatment planning and image guidance. This study aims to investigate the potential of probabilistic classification of voxels from multiple MRI contrasts to generate synthetic CT (‘MRCT’) images. The method consists of (1) acquiring multiple MRI volumes: T1-weighted, T2-weighted, two echoes from a ultra-short echo time (UTE) sequence, and calculated fat and water image volumes using a Dixon method, (2) classifying tissues using fuzzy c-means clustering with a spatial constraint, (3) assigning attenuation properties with weights based on the probability of individual tissue classes being present in each voxel, and (4) generating a MRCT image volume from the sum of attenuation properties in each voxel. The capability of each MRI contrast to differentiate tissues of interest was investigated based on a retrospective analysis of ten patients. For one prospective patient, the correlation of skull intensities between CT and MR was investigated, the discriminatory power of MRI in separating air from bone was evaluated, and the generated MRCT image volume was qualitatively evaluated. Our analyses showed that one MRI volume was not sufficient to separate all tissue types, and T2-weighted images was more sensitive to bone density variation compared to other MRI image types. The short echo UTE image showed significant improvement in contrasting air versus bone, but could not completely separate air from bone without false labeling. Generated MRCT and CT images showed similar contrast between bone and soft/solid tissues. These results demonstrate the potential of the presented method to generate synthetic CT images to support the workflow of radiation oncology treatment planning and image guidance.

Development and application research on thoracic-abdominal tumor precise positioning puncture devices

Objective To investigate the development and application of thoracic-abdominal tumor precise positioning puncture devices.Methods Based on the principle of locating and pendulum,as well as the isocenter multi-angle non-coplanar light principle on the chest and abdomen precise radiation therapy,the thoracic-abdominal tumor precise positioning puncture devices was developed with the use of tumor center spatial location method and radiotherapy positioning coordination system transfer method of radiation oncology treatment planning system (TPS).Results The device was applied to puncture chest tumor,reaching 100％ accuracy rate of one time biopsy.The average error in the space between tumor center (pre-puncture points) and actual puncture point (the actual arrival at the needle tip) was 2.59 mm,and the average displacement in the space distance of skin marker was 0.56 mm.Conclusion Using the newly developed thoracic-abdominal tumor precise positioning puncture devices can reduce the dependence on doctor's experience and the technique,as well can significantly improve the accuracy rate of puncture.As a result,it is a promising device which can be put in application. Key words: Cancer; Puncture; Positioning error; Coordinate system

Evaluation of process control in radiation oncology treatment planning.

186 Background: ROTP extends from simulation (SIM) through the start of treatment and constitutes a sequence of processes. Accurate implementation of each of these is essential for proper treatment. Prior guidelines had been proposed in our department for conformal treatment and intensity modulated radiation therapy (IMRT) or Volumetric Modulated Arc Therapy (VMAT); these were often not met leading to dissatisfaction by staff and patients. To improve this we evaluated the current steps in ROTP in an effort to improve our process. Methods: We analyzed the records of 157 eligible patients who underwent CT simulation from 1/1/12 through 3/30/12, excluding patients treated for benign disease, brachytherapy, or patients who never started treatment. The departmental standard was for urgent cases to start within 4 days (d), non-IMRT cases to start in 5d and IMRT/VMAT/SBRT cases to start in 10d. We defined three intervals, from SIM to start of treatment, SIM to approval of the plan by the physician, and approval to treatment start. Results: The median interval between planning landmarks in work-days and the % exceeding planning standards plus 2 days are shown below. Almost half of cases exceeded departmental standards for timeliness of ROTP. Much of the variability occurred after the physician had approved the plan. Conclusions: To improve timeliness of ROTP we have introduced changes in our planning process: 1. Strict definition of urgent cases. 2. Assigning a start date at the time of simulation. 3. Case planning review by the Radiation Oncologist, dosimetrist (+/- Physicist) at SIM. 4. Daily review of task list by Chief of Physics and Department Chair. These changes have been implemented in our department and results of the first two months of their use will be presented. [Table: see text]

MRCT: Synthetic CT Imaging for Radiation Oncology Using Magnetic Resonance Images

Purpose/Objective(s): MRI is an essential element of Radiation Oncology treatment planning. The ability of MRI data to yield synthetic CT images, specifically to define attenuation of skeletal features for dose calculation and image guidance support, was evaluated. Materials/Methods: Under a review board approved investigation, CT and various contrastMRI imageswere acquired of a dog. Imagevolumes acquired included 3D T1 gradient echo, T2 weighted, calculated water and fat (from a Dixon technique), and ultra short TE (UTE1, 70 microsecond echo time, followed by UTE2 at 3.7 ms). UTE1 images have signal intensities that are more strongly influenced by short T2 species, and show promise for separation of bone and air. Following intensity masking for separation of bone from air (using T1, UTE and water images), a classification algorithm (fuzzy c-means)was applied to themulti-spectralMRI volumes, yielding probability distributions for 5 classes (water, fat, brain, muscle, bone). Attenuationvalues were applied to each of the 5 classes and the resulting values were summed, yielding a synthetic CT (MRCT) volume. The actual CT volume was rigidly aligned with the MRI volumes (with specific focus on the skull). Regions of interest were defined based on increasing intensity thresholds on the CT scan (from400-1300HU in 300HUsteps), representing regions of increasing bone density. Intensities within these regions were evaluated on the MRCT. Intensities of MRI volumes of each contrast, as well as probabilities of class membership, were similarly evaluated within the same regions of interest. Results: Each of the input imaging sequences showed a trend of decreasing average signal intensity for regions generated via increasing CT thresholds, as expected due to the loss of signal in tissues with bone. All tissue classes except for bone decreased in membership probability in regions of increasing CT intensity, with the exception of the bone class, which increased with increasing CT value. Intensities within regions of varying bone density in the MRCT volume correlated strongly with those of the actual CT (R of 0.994). Digitally reconstructed radiographs from the actual CT volume were successfully aligned to matching projections through MRCT volumes without bias. Conclusions: The information present in MRI is sufficient to support identification and spatial mapping of skeletal features and classification can properly assign attenuation values to the heterogeneous skeletal tissues in the head. Further work will focus on assessing the accuracy of mapped attenuation of other tissues in the body and on treatment plan and IGRT comparisons using actual and synthetic CT data. Author Disclosure: Y. Cao: E. Research Grant; NIH. S. Hsu: None. A. Flammang: A. Employee; Siemens Corporate Research. J. Balter: E. Research Grant; NIH.

Characteristics of x-ray beams in two commercial multidetector computed tomography simulators: Monte Carlo simulations

As multidetector computed tomography (MDCT) scanning is routinely performed for treatment planning in radiation oncology, understanding the characteristics of the MDCT x-ray beam is essential to accurately estimate patient dose. The purpose of this study is to characterize the x-ray beams of two commercial MDCT simulators widely used in radiation oncology by Monte Carlo (MC) simulations. X-ray tube systems of two wide bore MDCT scanners (GE LightSpeed RT 4 and Philips Brilliance Big Bore) were modeled in the BEAMNRC/EGSNRC MC system. All the tube components were modeled from targets to bowtie filters. To validate our MC models, the authors measured half-value layers (HVL) using aluminum sheets and multifunctional radiation detectors and compared them to those obtained from MC simulations for 120 kVp beams. The authors also compared x-ray spectra obtained from MC simulation to the data provided by manufacturers. Additionally, lateral/axial beam profiles were measured in-air using radiochromic films and compared to the MC results. To understand the scatter effect, the authors also derived the scatter-to-primary energy fluence ratio (SPR) profiles and calculated the total SPR for each CT system with the CT dose index (CTDI) head and body phantoms using the BEAMNRC system. The authors found that the HVL, x-ray spectrum and beam profiles of the MC simulations agreed well with the manufacturer-specified data within 1%-10% on average for both scanners. The total SPR were ranged from 7.8 to 13.7% for the head phantom and from 10.7 to 18.9% for the body phantom. The authors demonstrate the full MC simulations of two commercial MDCT simulators to characterize their x-ray beams. This study may be useful to establish a patient-specific dosimetry for the MDCT systems.

SU‐E‐I‐26: A Monte Carlo Based Study on X‐Ray Characteristics of Two Commercial Multi‐Detector CT Simulators

Purpose: As multi‐detector computed tomography (MDCT) scan is routinely performed for treatment planning in radiation oncology, understanding the characteristics of MDCT x‐ray beam is essential to optimize scan protocols as well as to estimate patient dose. The purpose of this study was to characterize the x‐ray beams of two commercial MDCT simulators with Monte Carlo (MC) simulations. Methods: X‐ray tube systems of two wide bore MDCT scanners (GE LightSpeed RT, LS and Philips Brilliance Big Bore, BB) were modeled in the BEAMnrc/EGSnrc systems. All the tube components were modeled: tungsten target, inherent filter, bowtie filter, and beam collimators. Three benchmark processes were performed to validate the MC models. (1) X‐ray spectra comparison between MC and manufacturersˈ data, (2) Half‐value layers (HVLs) between MC and measurements using aluminum sheets and multi‐functional radiation detectors, (3) Lateral and axial beam profiles between MC and radiochromic film measurements To understand the scatter effect of the MDCT beams, scatter‐to‐primary energy fluence ratios (SPRs) were derived and the total SPR for each CT system was calculated with CTDI head and body phantoms.. Results: MC generated x‐ray spectra agreed well with the manufacturer‐specified data over the entire energy range. Effective photon beam energies for 120kVp beam were found to be (MC, vendor‐specified): (60.8, 60.2keV) for LS scatter, and (65.4, 64.9keV) for BB scanner. MC‐computed HVLs were found to be within 1% of the ion chamber measurements on average. The lateral and axial profiles between film and MC showed overall good agreement within 10% on average. The total SPR ranged from 3.5 to 4.9% for head phantom and from 7.1 to 11.1% for body phantom. Conclusion: Complete characterizations of two MDCT scanners have been performed using the BEAMnrc/EGSnrc MC system. This information can be utilized to optimize scan protocols as well as patient‐specific dosimetry for the MDCT systems.

The effect of acquisition time on visual and semi-quantitative analysis of F-18 FDG-PET studies in patients with head and neck cancer

To evaluate the impact of acquisition time on F-18 fluorodeoxyglucose positron emission tomography (PET) image quality, lesion detection rate, standard uptake and lesion volume measures. In 17 consecutively referred head and neck cancer patients, a 10-min acquisition of the head and neck was performed in list mode after completion of a whole-body PET-computed tomography scan. For each patient, 0.5, 1, 2, 3, 5, 7 and 10-min PET images were reconstructed. Image quality was scored on a 5-point scale. Lesions were visually identified and lesion locations were compared between scans with various acquisition times. Standard uptake values (SUVs) and lesion volumes were automatically obtained and compared. Image quality was scored excellent/good for 10 and 7-min scans; moderate for 5 and 3-min scans and poor/very poor for 2, 1 and 0.5-min scans. Lesion detection rate did not differ between scans with shorter acquisition times and the reference. Similarly, SUVmax was not significantly different between images with various scan times and the reference, except for the 0.5-min PET image (Wilcoxon, P = 0.04). Overall, lesion volume increased significantly with longer scan time (Friedman, P<0.0001). For individual lesions, however, the effect of scan time on volume was quite variable. The variability was significantly larger for images with scan times below 3 min than for images with scan times of > or = 3 min. Despite poor image quality for scans with short acquisition times, the lesion detection rate was not adversely affected. Increased scan time resulted in an increase in lesion volumes. This finding is of particular interest if PET images are implemented in radiation oncology treatment planning.

Treatment planning in Radiation Oncology

Treatment planning in Radiation Oncology

WE‐B‐211A‐01: Strengths and Limitations of Anatomical and Spectroscopic MRI in Radiation Oncology Treatment Planning

Magnetic resonance imaging (MRI) is playing an increasingly important role in radiation oncology treatment planning. As compared to computed tomography (CT), MRI provides excellent soft tissue contrast making it ideal for imaging brain tumors. Other anatomical sites (e.g., prostate, pelvis, head and neck, extremities, abdomen, etc.) also benefit from the soft tissue contrast provided by MRI, but are limited by difficulties in reproducing CT patient positioning in the MRI as well as geometric distortions introduced within the MRI datasets. These issues will be described, along with techniques for their minimization and quantification. MRI is also a powerful and non‐invasive imaging modality to assess tissue motion, caused by a host of physiological processes (respiration, peristalsis, bladder and/or rectal filling, etc.). Clinical approaches to using MRI for motion management will be described.In addition to morphological imaging, magnetic resonance spectroscopic imaging (MRSI) provides a non‐invasive spatial mapping of abnormal tumor metabolism. This information may provide critically relevant assessment of the presence and extent of tumor activity, which may be substantially different from those considered to contain tumor based on T1 and T2 imaging. Many uncertainties remain: geometric and quantification accuracy of the acquired MRSI data due to magnetic field imperfections, lack of adequate anatomical details with MRSI images for registration with planning CT, and lacking essential DICOM objects hamper the incorporation of MRSI information into the treatment planning process. Clinical approaches to using MRSI for tumor target delineation will also be described.This lecture will outline the indications for MRI in radiation oncology treatment planning for both external beam and brachytherapy. Examples are provided for many anatomical sites, along registration of MRI datasets with PET/CT. Approaches that can be used to validate MRI applications will be provided, along with a description of the current limitations.Learning Objectives:1. Widespread applications of MRI in radiation oncology treatment planning2. Assessment of geometric distortion when MRI is utilized as one of several imaging modalities: reproducibility of patient setup and image distortion3. Application of MRI to quantify and validate motion management models4. Review obstacles to clinical utilization of magnetic resonance spectroscopic imaging (MRSI)Research sponsored by Siemens Medical Solutions

SU‐GG‐T‐475: Volumetric Analysis of Moving Structures in Radiation Treatment Planning

Purpose: The purpose of this study is to design and validate a set of metrics for volumetric analysis of moving structures in radiation treatment planning. Method and Materials: 4D CT based treatment planning in thoracic radiation oncology requires a specific set of metrics for quantitative comparison of moving treatment planning volumes. For each pair of reference and test volumes axial overestimation and underestimation areas as functions of z coordinate are defined as the areas bounded by the set of contours in each axial slice. The axial underestimation and overestimation volumes are defined as integrals of corresponding areas along the z‐coordinate. The sagittal and coronal under/overestimation areas and volumes are defined analogously. An efficient and robust implementation for polygonal contours was obtained by using the Delaunay triangulation. The above metrics were used to compare different methods for determination of demonstrable respiratory motion of the GTV (iGTV) in 4‐D CT datasets. 27 patients with non‐small‐cell lung cancer (stage I: 17, stage III: 10) who underwent 4‐D CT simulation were studied. The iGTV was determined manually by (a) combining the GTV contours from 10 phases (GTVAllPhases) (b) combining the GTV contours from two extreme respiratory phases (0 and 50%) (GTV2Phases) (c) contouring using the MIP (GTVMIP) and (d) contouring using the MIP followed by modification with visual verification in individual respiratory phases (GTVMIP_Modified). For comparison of different approaches, GTVAllPhases was used as the reference. Results: The proposed metrics were successfully applied to 27 patients to show that iGTV as determined from GTVMIP and GTV2Phases underestimated iGTV as determined from the reference GTVAllPhases. Modification of iGTV determined from GTVMIP based on visual verification of contours through each individual phase reduced the degree of underestimation. Conclusion: The constructed metrics provide very good tools for volumetric analysis of moving structures.

A Bridge Between Academic and Community Radiation Oncology Treatment Planning

To evaluate Telesynergy (TS) as a method of interactive treatment planning between academic and community radiation oncology departments. Through a grant from the National Cancer Institute to improve cancer outcomes for underserved populations, community radiation oncologists at New Hanover Regional Medical Center (NHRMC) in Wilmington, North Carolina, partnered with those at the University of North Carolina (UNC) in Chapel Hill, North Carolina. TS suites were installed at both sites to facilitate teleconferencing and review of treatment planning for intensity-modulated radiation therapy (IMRT). Patients with locally advanced head and neck cancer at NHRMC who were enrolled on a clinical trial of chemoirradiation underwent IMRT planning utilizing commercial software. NHRMC physicians contoured tumor targets and adjacent healthy organs. Physics staff at NHRMC generated an initial IMRT plan for each patient. Radiation oncologists at UNC then reviewed individual IMRT plans via TS conferences. Between August 2004 and August 2005, seven IMRT plans were reviewed in eight TS conferences. Physician contours of tumor targets and healthy organs, dose volume histograms, IMRT beams, and isodose distributions were shared during each TS conference successfully. Median time for each session was 35 minutes (range, 30 to 75). Physician satisfaction with the interactive planning process was high at both NHRMC and UNC. A cycle would likely evolve of initial intensive use of TS conferences, to gradual use for ongoing quality control, then greater use as the treatment planning technology undergoes its next change. Complex IMRT treatment planning review was feasible between an academic and community hospital via TS with a high level of physician participant satisfaction.

147 The convergence of technology in radiation oncology treatment planning: Innovation in a Canadian undergraduate radiation therapy curriculum to support dual certification of radiation therapists

147 The convergence of technology in radiation oncology treatment planning: Innovation in a Canadian undergraduate radiation therapy curriculum to support dual certification of radiation therapists

Positron emission tomography in pediatric radiation oncology: integration in the treatment-planning process.

The application of PET imaging to pediatric radiation oncology allows new approaches to targeting and selection of radiation dose based not only on the size of a tumor, but also on its metabolic activity. In order to integrate PET into treatment planning for radiation oncology, logistical issues regarding patient setup, image fusion, and target selection must be addressed. Through prospective study, the role of PET in pediatric malignancies will be established for diagnosis, treatment, and surveillance. To explore the potential role of PET and its incorporation into treatment planning in pediatric radiation oncology, an example case of pediatric Hodgkin's disease is discussed.

Breathing-synchronized radiotherapy program at the University of California Davis Cancer Center.

In this paper we present a complete description of the breathing synchronized radiotherapy (BSRT) system, which has been jointly developed between the University of California Davis Cancer Center and Varian Associates. BSRT is a description of an emerging radiation oncology procedure, where simulation, CT scan, treatment planning, and radiation treatment are synchronized with voluntary breath-hold, forced breath-hold, or breathing gating. The BSRT system consists of a breathing monitoring system (BMOS) and a linear accelerator gating hardware and software package. Two methods, a video camera-based method and the use of wraparound inductive plethysmography (RespiTrace), generate the BMOS signals. The BMOS signals and the synchronized fluoroscopic images are simultaneously recorded in the simulation room and are later analyzed to define the ideal treatment point (ITP) where organ motion is stationary. The BMOS signals at ITP can be used to gate a CT scanner or a linear accelerator to maintain the same organ configuration as in the simulation. The BSRT system allows breath-hold or gating. This dual role allows the system to be applicable for a variety of patients, i.e., the breath-hold method for those patients who can maintain and reproduce the ITP, and the forced breath-hold or gating method for those who are not ideal for voluntary breath-hold.