Purpose
The number of pencil beam scanned proton therapy (PBS‐PT) facilities equipped with cone‐beam computed tomography (CBCT) imaging treating thoracic indications is constantly rising. To enable ...daily internal motion monitoring during PBS‐PT treatments of thoracic tumors, we assess the performance of Motion‐Aware RecOnstructiOn method using Spatial and Temporal Regularization (MA‐ROOSTER) four‐dimensional CBCT (4DCBCT) reconstruction for sparse‐view CBCT data and a realistic data set of patients treated with proton therapy.
Methods
Daily CBCT projection data for nine non‐small cell lung cancer (NSCLC) patients and one SCLC patient were acquired at a proton gantry system (IBA Proteus® One). Four‐dimensional CBCT images were reconstructed applying the MA‐ROOSTER and the conventional phase‐correlated Feldkamp‐Davis‐Kress (PC‐FDK) method. Image quality was assessed by visual inspection, contrast‐to‐noise ratio (CNR), signal‐to‐noise ratio (SNR), and the structural similarity index measure (SSIM). Furthermore, gross tumor volume (GTV) centroid motion amplitudes were evaluated.
Results
Image quality for the 4DCBCT reconstructions using MA‐ROOSTER was superior to the PC‐FDK reconstructions and close to FDK images (median CNR: 1.23 PC‐FDK, 1.98 MA‐ROOSTER, and 1.98 FDK; median SNR: 2.56 PC‐FDK, 4.76 MA‐ROOSTER, and 5.02 FDK; median SSIM: 0.18 PC‐FDK vs FDK, 0.31 MA‐ROOSTER vs FDK). The improved image quality of MA‐ROOSTER facilitated GTV contour warping and realistic motion monitoring for most of the reconstructions.
Conclusion
MA‐ROOSTER based 4DCBCTs performed well in terms of image quality and appear to be promising for daily internal motion monitoring in PBS‐PT treatments of (N)SCLC patients.
Purpose
Linear accelerator‐based stereotactic radiosurgery (SRS) has become a mainstay for simultaneous management of multiple intracranial targets. Recent improvements in treatment planning systems ...(TPS) have enabled treatment of multiple brain metastases using dynamic conformal arcs (DCA) and a single treatment isocenter. However, as the volume of healthy tissue receiving at least 12 Gy (V12) is linked to the probability of developing radionecrosis, balancing target coverage while minimizing V12 is a critical factor affecting SRS plan quality. Current TPS allow users to adjust various parameters influencing plan optimization. The purpose of this work is to quantify the effect of negative margins on V12 for cranial SRS plans managing multiple brain metastases.
Methods
Using the Brainlab Elements v3.0 TPS (Brainlab, Munich, Germany), we calculated V10, V12, V15, monitor units, and conformity index for seventeen SRS plans treating 2–10 metastases on our Elekta Versa HD (Elekta, Stockholm, Sweden) linear accelerator. We compared plans optimized using 70%‐90% prescription isodose lines (IDL) in 5% increments.
Results
Irrespective of the number of treated metastases, optimization at a lower prescription IDL reduced V10, V12, and V15 and increased MU compared to the 90% IDL (p < 0.01). However, comparing the 70% and 75% IDL optimizations, there was little difference in tissue sparing. The conformity index showed no consistent trends at different IDLs due to a significant spread in case data.
Conclusion
For our plans treating up to 10 metastases, diminishing returns for tissue sparing at IDLs below 80% paired with increasing treatment MU and dosimetric hot spot made optimization at lower IDLs less favorable. In our clinic, after consulting with a physician, it was determined that optimization at the 80% IDL achieved the best balance of V12, treatment MU, and maximum dose. Clinics implementing LINAC‐based SRS programs may consider using similar evaluations to develop their own clinical protocols.
Subungual Squamous Cell Carcinoma Rosen, Lane R.; Powell, Kevin; Katz, Sanford R. ...
American journal of clinical dermatology,
01/2010, Letnik:
11, Številka:
4
Journal Article
Recenzirano
We report the outcomes of three patients who were treated with external beam radiotherapy as an alternative to distal phalanx amputation for subungual squamous cell carcinomas between December 2004 ...and September 2006. The patients’ ages ranged from 46 to 83 years and the median follow-up time was 48 months (range: 36–52 months). As of the current date, the three patients show no signs of recurrence following a course of external beam radiotherapy. Complete function of the treated digit was obtained in all three patients.
Irradiation should be considered as an alternative modality choice in the treatment of subungual squamous cell carcinoma in lieu of distal phalanx amputation.
This study quantifies the dosimetric accuracy of a commercial treatment planning system as functions of treatment depth, air gap, and range shifter thickness for superficial pencil beam scanning ...proton therapy treatments. The RayStation 6 pencil beam and Monte Carlo dose engines were each used to calculate the dose distributions for a single treatment plan with varying range shifter air gaps. Central axis dose values extracted from each of the calculated plans were compared to dose values measured with a calibrated PTW Markus chamber at various depths in RW3 solid water. Dose was measured at 12 depths, ranging from the surface to 5 cm, for each of the 18 different air gaps, which ranged from 0.5 to 28 cm. TPS dosimetric accuracy, defined as the ratio of calculated dose relative to the measured dose, was plotted as functions of depth and air gap for the pencil beam and Monte Carlo dose algorithms. The accuracy of the TPS pencil beam dose algorithm was found to be clinically unacceptable at depths shallower than 3 cm with air gaps wider than 10 cm, and increased range shifter thickness only added to the dosimetric inaccuracy of the pencil beam algorithm. Each configuration calculated with Monte Carlo was determined to be clinically acceptable. Further comparisons of the Monte Carlo dose algorithm to the measured spread‐out Bragg Peaks of multiple fields used during machine commissioning verified the dosimetric accuracy of Monte Carlo in a variety of beam energies and field sizes. Discrepancies between measured and TPS calculated dose values can mainly be attributed to the ability (or lack thereof) of the TPS pencil beam dose algorithm to properly model secondary proton scatter generated in the range shifter.
This paper summarizes clinical commissioning of the world's first commercial, clinically utilized installation of a compact, image‐guided, pencil‐beam scanning, intensity‐modulated proton therapy ...system, the IBA Proteus®ONE, at the Willis‐Knighton Cancer Center (WKCC) in Shreveport, LA. The Proteus®ONE is a single‐room, compact‐gantry system employing a cyclotron‐generated proton beam with image guidance via cone‐beam CT as well as stereoscopic orthogonal and oblique planar kV imaging. Coupling 220° of gantry rotation with a 6D robotic couch capable of in plane patient rotations of over 180° degrees allows for 360° of treatment access. Along with general machine characterization, system commissioning required: (a) characterization and calibration of the proton beam, (b) treatment planning system commissioning including CT‐to‐density curve determination, (c) image guidance system commissioning, and (d) safety verification (interlocks and radiation survey). System readiness for patient treatment was validated by irradiating calibration TLDs as well as prostate, head, and lung phantoms from the Imaging and Radiation Oncology Core (IROC), Houston. These results confirmed safe and accurate machine functionality suitable for patient treatment. WKCC also successfully completed an on‐site dosimetry review by an independent team of IROC physicists that corroborated accurate Proteus®ONE dosimetry.
This article summarizes a volume-based method by which secondary monitor unit (MU) calculations may be performed for pencil beam scanning, single field uniform dose (SFUD) proton therapy treatment ...plans.
Treatment planning system (TPS) simulations were performed by using the local beam model to define relationships between planning target volume (PTV) characteristics and the MUs required to deliver a uniform dose for a given beam orientation. Relevant target attributes included volume, depth (ie, beam range), range-shifter air gap, and the projected area of the target volume in the beam's eye view (BEV). The proposed model approximates the PTV as a simplified cuboid region of interest as defined by its volume and BEV projected area. Output factors (cGy/MU) were then tabulated for the idealized geometry through TPS simulations using region of interests with a range of dimensions expected to be seen clinically. Correction factors were applied that account for differences between the PTV and the idealized conditions, and MUs for each beam were then scaled according to the measured spread out Bragg peak (SOBP) dose in water.
Our model was applied to various treatment sites, including pelvis, brain, lung, and head and neck. Monitor units prescribed by the TPS were compared to those predicted by using the model for 78 treatment beams. The total mean percentage difference for all beams was -0.2% ± 3.8%.
This work demonstrates the potential for reasonably accurate secondary verification of MUs in pencil beam scanning proton therapy for SFUD treatment plans with the proposed method. Required inputs are few, and are readily accessible, facilitating automation and clinical application. Further investigation will expand the current model to accommodate a broader range of potential optimization problems, and intensity-modulated proton therapy treatment plans.
碩士
義守大學
管理學院管理碩士在職專班
101
Electronic medical information has become the global trend. Since the Department of Health, Executive Yuan has promoted the electronic medical records in 2000, 274 hospitals ...and clinics have been included. Promoting the electronic medical records not only provides the continual medical services and upgrades the quality and efficiency, but also minimizes the overlapping of medical resource and decreases the costs. On the other hand, the privacy is getting more important. The electronic medical records are the database of the personal and medical information. The bad maintenance of information could result in leaking of personal data and rights damage including the discrimination, fraud and etc. The violators (hospital or staff) could also be liable for the civil and criminal responsibilities.
There have been many studies on the privacy of electronic medical records mainly on the importance of privacy, the impact of leaking and the improvement of information system security. Nothing is
Objective
This study aimed to characterize clinical outcomes with 18F-fluorodeoxyglucose positron emission tomography (FDG-PET)/computed tomography (CT) scan results at different follow-up time ...points following stereotactic body radiation therapy (SBRT) for early stage non-small cell lung cancer (NSCLC).
Methods
Records of 83 patients with early stage NSCLC treated with definitive SBRT were reviewed. FDG-PET/CT scans were obtained prior to treatment, at 4 months following treatment, and serially every 6 months thereafter on all surviving patients. The FDG uptake by lesions was assessed visually as the presence or absence of focal abnormal metabolic uptake compared to pretreatment lesions and termed PET-positive or PET-negative, respectively. When available, the maximum standardized uptake value (SUV
max
) was calculated to assess semiquantitative values.
Results
No correlation between PET-positive or PET-negative scan at the 4-month time interval and overall survival was observed. The 3-year overall survival for those patients with a PET-negative scan at 10 months was 60.9 % versus a 3-year overall survival of 20.8 % for patients with a PET-positive scan at that same follow-up date (
P
= 0.001; hazard ratio (HR) = 2.86, 95 % confidence interval (CI), 1.91–12.05).
Conclusion
FDG-PET/CT scans commonly remained positive with focal FDG uptake at 4 months following SBRT; however, this did not always indicate recurrent or residual disease. PET-negative scans at 10 months following SBRT correlated with increased overall survival.
Background: To determine the influence of patient and tumor characteristics on clinical outcomes in patients with early‐stage non‐small cell lung cancer (NSCLC) treated with helical intensity ...modulated stereotactic body radiotherapy (SBRT).
Methods: From March 2005 to August 2010 a total of 62 patients with biopsy proven Stage I NSCLC underwent helical SBRT with 48 Gy in 4 fractions or 60 Gy in 5 fractions. Patient and tumor characteristics including tumor stage, age, sex, tumor histology, maximal tumor diameter, and smoking history, were evaluated in regard to local control and overall survival using Kaplan‐Meier survival curves and the Cox proportional hazard method. Treatment related toxicity in the patient subgroups was evaluated.
Results: The median follow‐up was 28 months. Total cohort local control was 93.55% and 3‐year overall survival (OS) was 53.4%. Those patients with Stage IA disease had a 3‐year OS of 64.4% versus 32.1% for Stage IB disease (P = 0.042). Tumors classified as T1a (≤20 mm) and T1b (20–30 mm) had significantly increased overall survival compared to T2 (>30 mm) tumors (P = 0.046). There was a slight survival advantage in those patients with adenocarcinoma. No correlation between age, gender or smoking history, and overall survival was found. Nine patients had radiation related toxicity, which was increasingly more common with advancing age.
Conclusion: Helical SBRT is an effective method to treat NSCLC and the most significant prognostic factors were tumor stage and size. There was no correlation between age, gender, and smoking history.
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