bluuebunny/crossref_metadata_2025_split huggingface dataset:
Chimerism and T‐cell receptor repertoire analysis after unrelated cord blood transplantation with a reduced‐intensity conditioning regimen following autologous stem cell transplantation for multiple myeloma
Authors: TOUBAI T. , HIRATE D. , SHONO Y. , OTA S. , IBATA M. , MASHIKO S. , SUGITA J. , SHIGEMATSU A. , MIURA Y. , KATO N. , UMEHARA S. , KAHATA K. , TSUTSUMI Y. , IWAO N. , TOYOSHIMA N. , TANAKA J. , ASAKA M. , IMAMURA M. 
Published: February 2007

SummaryA 65‐year‐old Japanese male was diagnosed as multiple myeloma with Bence Jones kappa type, clinical stage IIIA. His disease status reached partial remission after chemotherapy. Thereafter, he received tandem transplantation, consisting of high‐dose chemotherapy with autologous stem cell transplantation (ASCT), followed by unrelated cord blood transplantation (U‐CBT). U‐CBT with a reduced‐intensity conditioning regimen (RI‐CBT) was performed in August 2003. HLA mismatch between the patient and the CBT donor was present at two serological loci (B and DR). A total nucleated CBT cell dose of 2.45 × 107/kg body weight was infused on day 0. Graft‐vs.‐host disease (GVHD) prophylaxis consisted of cyclosporine A and short‐term methotrexate. Neutrophil engraftment (>0.5 × 109/l) was obtained on day 46. He developed positive cytomegalovirus antigenemia, grade II acute GVHD involving skin and liver, varicella–zoster virus infection, septic shock, hemorrhagic cystitis caused by adenovirus and acute hepatitis B virus infection after U‐CBT. We retrospectively analyzed T‐cell receptor (TCR) repertoire diversity and found that TCR repertoire diversity decreased continuously after U‐CBT. Therefore, low‐TCR repertoire diversity in this patient appears to be associated with various infections caused by immunodeficiency.
Guide to clinical use of electronic portal imaging
Authors: Herman Michael G. , Kruse Jon J. , Hagness Christopher R. 
Published: February 2007

The Electronic Portal Imaging Device (EPID) provides localization quality images and computer‐aided analysis, which should in principal, replace portal film imaging. Modern EPIDs deliver superior image quality and an array of analysis tools that improve clinical decision making. It has been demonstrated that the EPID can be a powerful tool in the reduction of treatment setup errors and the quality assurance and verification of complex treatments. However, in many radiation therapy clinics EPID technology is not in routine clinical use. This low utilization suggests that the capability and potential of the technology alone do not guarantee its full adoption. This paper addresses basic considerations required to facilitate clinical implementation of the EPID technology and gives specific examples of successful implementations. © 2000 American College of Medical Physics.PACS number(s): 87.53.–j, 87.57.–s
On the need for monitor unit calculations as part of a beam commissioning methodology for a radiation treatment planning system
Authors: Starkschall George , Steadham Roy E. , Wells Nathan H. , O'Neill Laura , Miller Linda A. , Rosen Isaac I. 
Published: February 2007

This paper illustrates the need for validating the calculation of monitor units as part of the process of commissioning a photon beam model in a radiation treatment planning system. Examples are provided in which this validation identified subtle errors, either in the dose model or in the implementation of the dose algorithm. These errors would not have been detected if the commissioning process only compared relative dose distributions. A set of beam configurations, with varying field sizes, source‐to‐skin distances, wedges, and blocking, were established to validate monitor unit calculations for two different beam models in two different radiation treatment planning systems. Monitor units calculated using the treatment planning systems were compared with monitor units calculated from point dose calculations from tissue‐maximum ratio (TMR) tables. When discrepancies occurred, the dose models and the code were analyzed to identify the causes of the discrepancies. Discrepancies in monitor unit calculations were both significant (up to 5%) and systematic. Analysis of the dose computation software found: (1) a coordinate system transformation error, (2) mishandling of dose‐spread arrays, (3) differences between dose calculations in the commissioning software and the planning software, and (4) shortcomings in modeling of head scatter. Corrections were made in the beam calculation software or in the data sets to overcome these discrepancies. Consequently, we recommend incorporating validation of monitor unit calculations as part of a photon beam commissioning process.PACS number(s): 87.53.–j, 87.66.–a
Comparison between TG‐51 and TG‐21: Calibration of photon and electron beams in water using cylindrical chambers
Authors: Cho S. H. , Lowenstein J. R. , Balter P. A. , Wells N. H. , Hanson W. F. 
Published: February 2007

A new calibration protocol, developed by the AAPM Task Group 51 (TG‐51) to replace the TG‐21 protocol, is based on an absorbed‐dose to water standard and calibration factor , while the TG‐21 protocol is based on an exposure (or air‐kerma) standard and calibration factor . Because of differences between these standards and the two protocols, the results of clinical reference dosimetry based on TG‐51 may be somewhat different from those based on TG‐21. The Radiological Physics Center has conducted a systematic comparison between the two protocols, in which photon and electron beam outputs following both protocols were compared under identical conditions. Cylindrical chambers used in this study were selected from the list given in the TG‐51 report, covering the majority of current manufacturers. Measured ratios between absorbed‐dose and air‐kerma calibration factors, derived from the standards traceable to the NIST, were compared with calculated values using the TG‐21 protocol. The comparison suggests that there is roughly a 1% discrepancy between measured and calculated ratios. This discrepancy may provide a reasonable measure of possible changes between the absorbed‐dose to water determined by TG‐51 and that determined by TG‐21 for photon beam calibrations. The typical change in a 6 MV photon beam calibration following the implementation of the TG‐51 protocol was about 1%, regardless of the chamber used, and the change was somewhat smaller for an 18 MV photon beam. On the other hand, the results for 9 and 16 MeV electron beams show larger changes up to 2%, perhaps because of the updated electron stopping power data used for the TG‐51 protocol, in addition to the inherent 1% discrepancy presented in the calibration factors. The results also indicate that the changes may be dependent on the electron energy.PACS number(s): 87.66.–a, 87.53.–j
An investigation of eye lens dose for gamma knife treatments of trigeminal neuralgia
Authors: Ma Lijun , Chin Lawrence , Sarfaraz Mehrdad , Shepard David , Yu Cedric 
Published: February 2007

Stereotactic Gamma Knife radiosurgery has been widely used for treating trigeminal neuralgia (TN). A single large fractional dose of 7000 to 9000 cGy is commonly prescribed as the maximum dose for these treatments. For this reason, if a small percentage of the prescribed dose such as 2–3 % scattered to the eye, it could reach or even exceed the tolerance dose of the lens. For several TN cases, we found that the Leksell Gamma Plan system calculates the lens dose about 0.5–2 % of the maximum dose independent of the use of eye shielding. These dose values are significantly high and it motivated us to investigate the lens dose for the TN patients treated with stereotactic Gamma Knife radiosurgery. Phantom studies and in vivo dosimetry measurements were carried out for six patients treated at our institution. The average dose to the lens ipsilateral to the treated nerve was measured to be . Based on the biological model of Lyman and Emami [Int. J. Radiat. Oncol. Biol. Phys. 21, 109–122 (1991)], the probability of the lens complication (cataract) was determined to be 0.1%. Our findings suggest that few TN patients would develop cataracts after receiving Gamma Knife radiosurgery.PACS number(s): 87.53.–j, 87.66.–a
Independent corroboration of monitor unit calculations performed by a 3D computerized planning system
Authors: Leszczynski Konrad W. , Dunscombe Peter B. 
Published: February 2007

The checking of monitor unit calculations is recognized as a vital component of quality assurance in radiotherapy. Using straightforward but detailed computer‐based verification calculations it is possible to achieve a precision of 1% when compared with a three‐dimensional (3D) treatment planning system monitor unit calculation. The method is sufficiently sensitive to identify significant errors and is consistent with current recommendations on the magnitude of uncertainties in clinical dosimetry. Moreover, the approach is accurate in the sense of being highly consistent with the validated 3D treatment planning system's calculations.PACS number(s): 87.53.–j, 87.52.–g
Evaluation of an innovative plastic cube phantom designed to improve the efficiency of accelerator QA
Authors: Huang J. C. , Reinstein L. E. 
Published: February 2007

A new cubic phantom was designed to improve the efficiency on the QA measurement of accelerator. It has a variety of applications, such as dose constancy check, depth dose verifications, and symmetry and flatness evaluations. In particular, this new design makes it much easier to perform the check on output constancy vs. gantry angles as a cylindrical ion chamber positioned at the center of the phantom. The reproducibility of the setup using this phantom has been investigated. The charge effect of the phantom is found to be insignificant. It also reduces the monthly dosimetric QA time spent on a typical multimodality accelerator by approximately 40%.PACS number(s): 87.66.–a
Comparison of RTP dose distributions in heterogeneous phantoms with thebeamMonte Carlo simulation system
Authors: Miften Moyed , Wiesmeyer Mark , Kapur Ajay , Ma C.‐M. Charlie 
Published: February 2007

Therapeutic treatment plan evaluation is often based on examining the radiotherapy treatment planning (RTP) system dose distributions in the target and surrounding normal structures. To study the effects of tissue inhomogeneities on photon dose distributions, we compared FOCUS RTP system dose distributions from the measurement‐based Clarkson and model‐based MultiGrid Superposition (MGS) algorithms with those from thebeamMonte Carlo code system in a set of heterogeneous phantoms. The phantom inhomogeneities mimic relevant clinical treatment sites, which include lung slab, lung‐bone slab, bone‐lung slab, mediastinum, and tumor geometries. The benchmark comparisons were performed in lung densities of 0.20 and, and a bone density offorandand 15‐MV photon beams. Benchmark comparison results show that the MGS model andbeamdoses match better than 3% or 3 mm, and the MGS model is more accurate than the Clarkson model in all phantoms. The MGS model, unlike the Clarkson model, predicts the build‐down and build‐up of dose near tissue interfaces and penumbra broadening in lung associated with high energy beams. The Clarkson model overestimates the dose in lung by a maximum of 10% compared tobeam. Dose comparisons suggest turning‐off the effective path length inhomogeneity correction in the Clarkson model for lung treatments.PACS number(s): 87.53.–j, 87.53.Bn
The treatment of large extraskeletal chondrosarcoma of the leg: Comparison of IMRT and conformal radiotherapy techniques
Authors: Chan Maria F. , Chui Chen‐Shou , Schupakm Karen , Amols Howard , Burman Chandra , Ling C. Clifton 
Published: February 2007

Extraskeletal chondrosarcoma of the leg is a rare, malignant neoplasm with very few cases having been reported in the literature. In this study we investigate the possibility of using intensity modulated radiotherapy (IMRT) for this type of disease and demonstrate its advantages over conventional three‐dimensional (3D) conformal treatment. A case was presented of a patient with extraskeletal chondrosarcoma of the lateral compartment of the leg in which the target volume was 50 cm in length and twisted around the surrounding bones. Both the 3D conformal plan and IMRT plan were designed using the Memorial Sloan‐Kettering Cancer Center planning system. The IMRT plan produced a superior dose distribution to the patient as compared to the 3D conformal plan both in terms of dose conformity and homogeneity in the target volumes, and reduction of the maximum dose to the bone. The planning time of the IMRT plan was about 3–5 times shorter than that of the 3D conformal plan. It was demonstrated that the IMRT technique can be used not just for small tumors, but also for large and spiral‐shaped tumors close to critical organs. The IMRT method requires less planning time, and provides better target coverage with more sparing of critical structures. When planning patients with multiple target volumes receiving different prescribed doses, the IMRT technique can more easily meet this requirement.PACS number(s): 87.53.–j, 87.90.+y
The dose distribution of medium energy electron boosts to the laryngectomy stoma
Authors: Yorke Ellen D. , Kassaee Alireza , Doyle Todd , Loevner Laurie A. , Rosenthal David I. 
Published: February 2007

An en face, medium energy electron boost of approximately 10 Gy is often given to stomal and peristomal tissues. Because the boost is considered a simple treatment, CT‐based treatment planning is rarely used. Further, the results of such a plan might be inaccurate, as the complex dose distribution surrounding the stoma air cavity is poorly modeled by many treatment planning systems. We constructed three phantoms—two with a central vertical cavity to mimic the size and shape of the stoma and proximal trachea and one with a cavity inclined at 45° to the horizontal to better simulate anatomy. These were used to investigate the dose distribution surrounding the stoma. In all cases, the entrance to the stoma opening was centered in a field defined by a 7‐cm circular cutout and the phantom was irradiated at a source‐surface distance (SSD) of 100 cm with either vertically incident 9‐ or 12‐MeV electrons. Film measurements were made at a range of depths below and lateral to the cavity. For the vertical cavity phantoms, diode measurements were performed and isodose plans using CT scans of the phantoms were generated on a modern treatment planning system. For these two phantoms, the combined effects of lateral scatter from surrounding material and reduced equivalent thickness for electrons which pass directly through the cavity increases the dose within a centimeter of the bottom of cavity by as much as 50% for 9 MeV and 70% for 12 MeV. In material at the shallower (“superior”) end of the inclined cavity, a overdose was noted. The dose increase is geometry dependent and is not predicted by the available treatment planning system. The potential of such a dose increase to affect normal tissues such as the neopharynx should be considered.PACS number(s): 87.53.–j, 87.66.–a
An image fusion study of the geometric accuracy of magnetic resonance imaging with the Leksell stereotactic localization system
Authors: Yu Cheng , Petrovich Zbigniew , Apuzzo Michael L. J. , Luxton Gary 
Published: February 2007

A special acrylic phantom designed for both magnetic resonance imaging (MRI) and computed tomography (CT) was used to assess the geometric accuracy of MRI‐based stereotactic localization with the Leksell stereotactic head frame and localizer system. The acrylic phantom was constructed in the shape of a cube, 164 mm in each dimension, with three perpendicular arrays of solid acrylic rods, 5 mm in diameter and spaced 30 mm apart within the phantom. Images from two MR scanners and a CT scanner were obtained with the same Leksell head frame placement. Using image fusion provided by the Leksell GammaPlan (LGP) software, the coordinates of the intraphantom rod positions from two MRI scanners were compared to that of CT imaging. The geometric accuracy of MR images from the Siemens scanner was greatly improved after the implementation of a special software patch provided by the manufacturer. In general, much better accuracy was achieved in the transverse plane where images were acquired. Most distortion was found around the periphery while least distortion was present in the middle and most other parts of the phantom. For most intracranial lesions undergoing stereotactic radiosurgery, accuracy of target localization can be achieved within size of a voxel, especially with the Siemens scanner. However, extra caution should be taken for imaging of peripheral lesions where the distortion is the greatest.PACS number(s): 87.61.–c, 87.57.–s
Technical innovation to calibrate the gantry angle indicators of linear accelerators
Authors: Chang Liyun , Ho Sheng‐Yow , Wu Jia‐Ming , Yu Chin‐Yen , Sung Chien‐Chen 
Published: February 2007

Finding the actual zero degree of the gantry angle is important in order to perform the mechanical quality assurance (QA) of linear accelerators. To determine real zero, we must locate a “good surface” which could be defined as a plane on the surface of the gantry head that is perpendicular to the direction of radiation. The actual gantry angle could then be defined as the angle between vertical, as indicated by a plumb bob, and the direction of the beam axis that could be indicated by the position of a BB placed in the central axis and its shadow. From this we located the real zero degree and the good surface. The good surface can be applied to check the important mechanical readouts. The technique we introduce could solve the essential problems of a traditional QA technique, as well as taking up an important role in the quality assurance of a patient's treatment.PACS number(s): 87.56.–v
Development of a treatment planning protocol for prostate treatments using intensity modulated radiotherapy
Authors: Ezzell Gary A. , Schild Steven E. , Wong William W. 
Published: February 2007

We have developed a treatment planning protocol for intensity‐modulated radiation therapy of the prostate using commercially available inverse planning software. Treatment plans were developed for ten patients using the Corvus version 3.8 planning system, testing various prescription options, including tissue types, dose volume histogram values for the target and normal structures, beam arrangements, and number of intensity levels. All plans were scaled so that 95% of the clinical target volume received 75.6 Gy; mean doses to the prostate were typically 79 Gy. The reproducibility of the inverse planning algorithm was tested by repeating a set of the plans five times. Plans were deemed acceptable if they satisfied predefined dose constraints for the targets and critical organs. Figures of merit for target coverage, target dose uniformity, and organ sparing were used to rank acceptable plans. Certain systematic behaviors of the optimizer were noted: the high dose regions for both targets and critical organs were 5–10 Gy more than prescribed; reducing bladder and rectum tolerance increased the range of doses within the target; increasing the number of fields incrementally improved plan quality. A set of planning parameters was found that usually satisfied the minimum requirements. Repeating the optimization with different beam order produced similar but slightly different dose distributions, which was sometimes useful for finding acceptable solutions for difficult cases. The standard set of parameters serves as a useful starting point for individualized planning.PACS number(s): 87.53.–j, 87.90.+y
Geometry function of a linear brachytherapy source
Authors: King R. Paul , Anderson R. Scott , Mills Michael D. 
Published: February 2007

An equation is derived for the TG43 geometry function, G(r,θ), of a linear brachytherapy source in terms of its active length. This equation is validated by comparison to published values. It is then used to calculate values of the geometry function for the Model seed, which is a segmented linear source.PACS number(s): 87.53.–j
Evaluation of a quality control phantom for digital chest radiography
Authors: Mah Eugene , Samei Ehsan , Peck Donald J. 
Published: February 2007

Rationale and Objectives: To examine the effectiveness and suitability of a quality control (QC) phantom for a routine QC program in digital radiography. Materials and Methods: The chest phantom consists of copper and aluminum cutouts arranged to resemble the appearance of a chest. Performance of the digital radiography (DR) system is evaluated using high and low contrast resolution objects placed in the “heart,” “lung,” and “subdiaphragm” areas of the phantom. In addition, the signal levels from these areas were compared to similar areas from clinical chest radiographs. Results: The test objects included within the phantom were effective in assessing image quality except within the subdiaphragm area, where most of the low contrast disks were visible. Spatial resolution for the DR systems evaluated with the phantom ranged from 2.6 lp/mm to 4 lp/mm, falling within the middle of the line pair range provided. The signal levels of the heart and diaphragm regions relative to the lung region of the phantom were significantly higher than in clinical chest radiographs (0.67 versus 0.21 and 0.28 versus 0.10 for the heart and diaphragm regions, respectively). The heart‐to‐diaphragm signal level ratio, however, was comparable to those in clinical radiographs. Conclusion: The findings suggest that the attenuation characteristics of the phantom are somewhat different from actual chests, but this did not appear to affect the post‐processing used by the imaging systems and usefulness for QC of these systems. The qualitative and quantitative measurements on the phantom for different systems were similar, suggesting that a single phantom can be used to evaluate system performance in a routine QC program for a wide range of digital radiography systems. This makes the implementation of a uniform QC program easier for institutions with a mixture of different digital radiography systems.PACS number(s): 87.57.–s, 87.62.+n
Commissioning of a mobile electron accelerator for intraoperative radiotherapy
Authors: Mills Michael D. , Fajardo Liliosa C. , Wilson David L. , Daves Jodi L. , Spanos William J. 
Published: February 2007

Radiation performance characteristics of a dedicated intraoperative accelerator were determined to prepare the unit for clinical use. The linear accelerator uses standing wave X‐band technology (wavelength approximately 3 centimeters) in order to minimize the mass of the accelerator. The injector design, smaller accelerator components, and low electron beam currents minimize radiation leakage. The unit may be used in a standard operating room without additional shielding. The mass of the accelerator gantry is 1250 Kg (weight approximately 2750 lbs) and the unit is transportable between operating rooms. Nominal electron energies are 4, 6, 9, and 12 MeV, and operate at selectable dose rates of 2.5 or 10 Gray per minute. depths in water for a 10 cm applicator are 0.7, 1.3, 1.7, and 2.0 for these energies, respectively. The depths of 80% dose are 1.2, 2.1, 3.1, and 3.9 cm, respectively. Absolute calibration using the American Association of Physicists in Medicine TG‐51 protocol was performed for all electron energies using the 10 cm applicator. Applicator sizes ranged from 3 to 10 cm diameter for flat applicators, and 3 to 6 cm diameter for 30° beveled applicators. Output factors were determined for all energies relative to the 10 cm flat applicator. Central axis depth dose profiles and isodose plots were determined for every applicator and energy combination. A quality assurance protocol, performed each day before patient treatment, was developed for output and energy constancy.PACS number(s): 87.53.–j, 87.52.–g