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Sample records for external radiotherapy photon

  1. TOPICAL REVIEW: Monte Carlo modelling of external radiotherapy photon beams

    NASA Astrophysics Data System (ADS)

    Verhaegen, Frank; Seuntjens, Jan

    2003-11-01

    An essential requirement for successful radiation therapy is that the discrepancies between dose distributions calculated at the treatment planning stage and those delivered to the patient are minimized. An important component in the treatment planning process is the accurate calculation of dose distributions. The most accurate way to do this is by Monte Carlo calculation of particle transport, first in the geometry of the external or internal source followed by tracking the transport and energy deposition in the tissues of interest. Additionally, Monte Carlo simulations allow one to investigate the influence of source components on beams of a particular type and their contaminant particles. Since the mid 1990s, there has been an enormous increase in Monte Carlo studies dealing specifically with the subject of the present review, i.e., external photon beam Monte Carlo calculations, aided by the advent of new codes and fast computers. The foundations for this work were laid from the late 1970s until the early 1990s. In this paper we will review the progress made in this field over the last 25 years. The review will be focused mainly on Monte Carlo modelling of linear accelerator treatment heads but sections will also be devoted to kilovoltage x-ray units and 60Co teletherapy sources.

  2. Monte Carlo modelling of external radiotherapy photon beams.

    PubMed

    Verhaegen, Frank; Seuntjens, Jan

    2003-11-01

    An essential requirement for successful radiation therapy is that the discrepancies between dose distributions calculated at the treatment planning stage and those delivered to the patient are minimized. An important component in the treatment planning process is the accurate calculation of dose distributions. The most accurate way to do this is by Monte Carlo calculation of particle transport, first in the geometry of the external or internal source followed by tracking the transport and energy deposition in the tissues of interest. Additionally, Monte Carlo simulations allow one to investigate the influence of source components on beams of a particular type and their contaminant particles. Since the mid 1990s, there has been an enormous increase in Monte Carlo studies dealing specifically with the subject of the present review, i.e., external photon beam Monte Carlo calculations, aided by the advent of new codes and fast computers. The foundations for this work were laid from the late 1970s until the early 1990s. In this paper we will review the progress made in this field over the last 25 years. The review will be focused mainly on Monte Carlo modelling of linear accelerator treatment heads but sections will also be devoted to kilovoltage x-ray units and 60Co teletherapy sources. PMID:14653555

  3. Modulated photon radiotherapy (XMRT): an algorithm for the simultaneous optimization of photon beamlet energy and intensity in external beam radiotherapy (EBRT) planning

    NASA Astrophysics Data System (ADS)

    McGeachy, Philip; Villarreal-Barajas, Jose Eduardo; Zinchenko, Yuriy; Khan, Rao

    2016-02-01

    This is a proof of principle study on an algorithm for optimizing external beam radiotherapy in terms of both photon beamlet energy and fluence. This simultaneous beamlet energy and fluence optimization is denoted modulated photon radiotherapy (XMRT). XMRT is compared with single-energy intensity modulated radiotherapy (IMRT) for five clinically relevant test geometries to determine whether treating beamlet energy as a decision variable improves the dose distributions. All test geometries were modelled in a cylindrical water phantom. XMRT optimized the fluence for 6 and 18 MV beamlets while IMRT optimized with only 6 MV and only 18 MV. CERR (computational environment for radiotherapy research) was used to calculate the dose deposition matrices and the resulting dose for XMRT and IMRT solutions. Solutions were compared via their dose volume histograms and dose metrics, such as the mean, maximum, and minimum doses for each structure. The homogeneity index (HI) and conformity number (CN) were calculated to assess the quality of the target dose coverage. Complexity of the resulting fluence maps was minimized using the sum of positive gradients technique. The results showed XMRT’s ability to improve healthy-organ dose reduction while yielding comparable coverage of the target relative to IMRT for all geometries. All three energy-optimization approaches yielded similar HI and CNs for all geometries, as well as a similar degree of fluence map complexity. The dose reduction provided by XMRT was demonstrated by the relative decrease in the dose metrics for the majority of the organs at risk (OARs) in all geometries. Largest reductions ranged between 5% to 10% in the mean dose to OARs for two of the geometries when compared with both single-energy IMRT schemes. XMRT has shown potential dosimetric benefits through improved OAR sparing by allowing beam energy to act as a degree of freedom in the EBRT optimization process.

  4. Modulated photon radiotherapy (XMRT): an algorithm for the simultaneous optimization of photon beamlet energy and intensity in external beam radiotherapy (EBRT) planning.

    PubMed

    McGeachy, Philip; Villarreal-Barajas, Jose Eduardo; Zinchenko, Yuriy; Khan, Rao

    2016-02-21

    This is a proof of principle study on an algorithm for optimizing external beam radiotherapy in terms of both photon beamlet energy and fluence. This simultaneous beamlet energy and fluence optimization is denoted modulated photon radiotherapy (XMRT). XMRT is compared with single-energy intensity modulated radiotherapy (IMRT) for five clinically relevant test geometries to determine whether treating beamlet energy as a decision variable improves the dose distributions. All test geometries were modelled in a cylindrical water phantom. XMRT optimized the fluence for 6 and 18 MV beamlets while IMRT optimized with only 6 MV and only 18 MV. CERR (computational environment for radiotherapy research) was used to calculate the dose deposition matrices and the resulting dose for XMRT and IMRT solutions. Solutions were compared via their dose volume histograms and dose metrics, such as the mean, maximum, and minimum doses for each structure. The homogeneity index (HI) and conformity number (CN) were calculated to assess the quality of the target dose coverage. Complexity of the resulting fluence maps was minimized using the sum of positive gradients technique. The results showed XMRT's ability to improve healthy-organ dose reduction while yielding comparable coverage of the target relative to IMRT for all geometries. All three energy-optimization approaches yielded similar HI and CNs for all geometries, as well as a similar degree of fluence map complexity. The dose reduction provided by XMRT was demonstrated by the relative decrease in the dose metrics for the majority of the organs at risk (OARs) in all geometries. Largest reductions ranged between 5% to 10% in the mean dose to OARs for two of the geometries when compared with both single-energy IMRT schemes. XMRT has shown potential dosimetric benefits through improved OAR sparing by allowing beam energy to act as a degree of freedom in the EBRT optimization process. PMID:26808280

  5. Commissioning and quality assurance of the Pinnacle(3) radiotherapy treatment planning system for external beam photons.

    PubMed

    Bedford, J L; Childs, P J; Nordmark Hansen, V; Mosleh-Shirazi, M A; Verhaegen, F; Warrington, A P

    2003-03-01

    The commissioning of a Pinnacle(3) treatment planning system is described. Four Elekta linear accelerators were commissioned for external beam photons. Measured data were used to derive parameter values for the Pinnacle(3) beam model by (1). fitting a Monte Carlo model of the accelerator head to measured data and then extracting the parameters for the Pinnacle(3) beam model, and by (2). using the auto-modelling facility within Pinnacle(3). Both of these methods yielded dose distributions in accord with published recommendations. A separate small-field beam model, customized for an in-house compact blocking system, was also created, which satisfied appropriate acceptance criteria for stereotactically guided conformal brain treatments. Inhomogeneous, oblique, asymmetrical and irregular fields were also assessed, with calculated and measured doses agreeing to within +/-3%. Dose-volume histogram calculation was found to be accurate to within +/-5% dose or volume for a grid size of 4 mm x 4 mm x 4 mm, with better accuracy being achieved for finer grids. Isocentric doses were compared between Pinnacle(3)'s collapsed cone convolution algorithm and the Bentley-Milan algorithm within the Target-2 treatment planning system. Dose differences were generally less than 3% in the dose prescribed, with larger values for breast plans, where the Pinnacle(3) algorithm calculated scatter more accurately. Pelvic and thoracic plans were also verified using an anthropomorphic phantom, with local dose differences between calculated and delivered dose of up to 8%, but mainly less than 3%, and with no systematic difference. Ionization chamber verifications using START and RT-01 trial procedures demonstrated differences between calculated and measured doses of less than 2%. Following satisfactory performance in the commissioning process, Pinnacle(3) has now been introduced into routine clinical use. PMID:12684232

  6. [Prostate cancer external beam radiotherapy].

    PubMed

    de Crevoisier, R; Pommier, P; Latorzeff, I; Chapet, O; Chauvet, B; Hennequin, C

    2016-09-01

    The prostate external beam radiotherapy techniques are described, when irradiating the prostate or after prostatectomy, with and without pelvic lymph nodes. The following parts are presented: indications of radiotherapy, total dose and fractionation, planning CT image acquisition, volume of interest delineation (target volumes and organs at risk) and margins, Intensity modulated radiotherapy planning and corresponding dose-volume constraints, and finally Image guided radiotherapy. PMID:27516051

  7. The influence of neutron contamination on dosimetry in external photon beam radiotherapy

    SciTech Connect

    Horst, Felix Czarnecki, Damian; Zink, Klemens

    2015-11-15

    Purpose: Photon fields with energies above ∼7 MeV are contaminated by neutrons due to photonuclear reactions. Their influence on dosimetry—although considered to be very low—is widely unexplored. Methods: In this work, Monte Carlo based investigations into this issue performed with FLUKA and EGSNRC are presented. A typical Linac head in 18 MV-X mode was modeled equivalently within both codes. EGSNRC was used for the photon and FLUKA for the neutron production and transport simulation. Water depth dose profiles and the response of different detectors (Farmer chamber, TLD-100, TLD-600H, and TLD-700H chip) in five representative depths were simulated and the neutrons’ impact (neutron absorbed dose relative to photon absorbed dose) was calculated. To take account of the neutrons’ influence, a theoretically required correction factor was defined and calculated for five representative water depths. Results: The neutrons’ impact on the absorbed dose to water was found to be below 0.1% for all depths and their impact on the response of the Farmer chamber and the TLD-700H chip was found to be even less. For the TLD-100 and the TLD-600H chip it was found to be up to 0.3% and 0.7%, respectively. The theoretical correction factors to be applied to absorbed dose to water values measured with these four detectors in a depth different from the reference/calibration depth were calculated and found to be below 0.05% for the Farmer chamber and the TLD-700H chip, but up to 0.15% and 0.35% for the TLD-100 and TLD-600H chips, respectively. In thermoluminescence dosimetry the neutrons’ influence (and therefore the additional inaccuracy in measurement) was found to be higher for TLD materials whose {sup 6}Li fraction is high, such as TLD-100 and TLD-600H, resulting from the thermal neutron capture reaction on {sup 6}Li. Conclusions: The impact of photoneutrons on the absorbed dose to water and on the response of a typical ionization chamber as well as three different types

  8. In vivo dosimetry in external beam radiotherapy

    SciTech Connect

    Mijnheer, Ben; Beddar, Sam; Izewska, Joanna; Reft, Chester

    2013-07-15

    In vivo dosimetry (IVD) is in use in external beam radiotherapy (EBRT) to detect major errors, to assess clinically relevant differences between planned and delivered dose, to record dose received by individual patients, and to fulfill legal requirements. After discussing briefly the main characteristics of the most commonly applied IVD systems, the clinical experience of IVD during EBRT will be summarized. Advancement of the traditional aspects of in vivo dosimetry as well as the development of currently available and newly emerging noninterventional technologies are required for large-scale implementation of IVD in EBRT. These new technologies include the development of electronic portal imaging devices for 2D and 3D patient dosimetry during advanced treatment techniques, such as IMRT and VMAT, and the use of IVD in proton and ion radiotherapy by measuring the decay of radiation-induced radionuclides. In the final analysis, we will show in this Vision 20/20 paper that in addition to regulatory compliance and reimbursement issues, the rationale for in vivo measurements is to provide an accurate and independent verification of the overall treatment procedure. It will enable the identification of potential errors in dose calculation, data transfer, dose delivery, patient setup, and changes in patient anatomy. It is the authors' opinion that all treatments with curative intent should be verified through in vivo dose measurements in combination with pretreatment checks.

  9. Proton Radiotherapy for Liver Tumors: Dosimetric Advantages Over Photon Plans

    SciTech Connect

    Wang Xiaochun Krishnan, Sunil; Zhang Xiaodong; Dong Lei; Briere, Tina; Crane, Christopher H.; Martel, Mary; Gillin, Michael; Mohan, Radhe; Beddar, Sam

    2008-01-01

    The purpose of the study is to dosimetrically investigate the advantages of proton radiotherapy over photon radiotherapy for liver tumors. The proton plan and the photon plan were designed using commercial treatment planning systems. The treatment target dose conformity and heterogeneity and dose-volume analyses of normal structures were compared between proton and photon radiotherapy for 9 patients with liver tumors. Proton radiotherapy delivered a more conformal target dose with slightly less homogeneity when compared with photon radiotherapy. Protons significantly reduced the fractional volume of liver receiving dose greater or equal to 30 Gy (V{sub 30}) and the mean liver dose. The stomach and duodenal V{sub 45} were significantly lower with the use of proton radiotherapy. The V{sub 40} and V{sub 50} of the heart and the maximum spinal cord dose were also significantly lower with the use of proton radiotherapy. Protons were better able to spare one kidney completely and deliver less dose to one (generally the left) kidney than photons. The mean dose to the total body and most critical structures was significantly decreased using protons when compared to corresponding photon plans. In conclusion, our study suggests the dosimetric benefits of proton radiotherapy over photon radiotherapy. These dosimetric advantages of proton plans may permit further dose escalation with lower risk of complications.

  10. Optimization approaches for planning external beam radiotherapy

    NASA Astrophysics Data System (ADS)

    Gozbasi, Halil Ozan

    Cancer begins when cells grow out of control as a result of damage to their DNA. These abnormal cells can invade healthy tissue and form tumors in various parts of the body. Chemotherapy, immunotherapy, surgery and radiotherapy are the most common treatment methods for cancer. According to American Cancer Society about half of the cancer patients receive a form of radiation therapy at some stage. External beam radiotherapy is delivered from outside the body and aimed at cancer cells to damage their DNA making them unable to divide and reproduce. The beams travel through the body and may damage nearby healthy tissue unless carefully planned. Therefore, the goal of treatment plan optimization is to find the best system parameters to deliver sufficient dose to target structures while avoiding damage to healthy tissue. This thesis investigates optimization approaches for two external beam radiation therapy techniques: Intensity-Modulated Radiation Therapy (IMRT) and Volumetric-Modulated Arc Therapy (VMAT). We develop automated treatment planning technology for IMRT that produces several high-quality treatment plans satisfying provided clinical requirements in a single invocation and without human guidance. A novel bi-criteria scoring based beam selection algorithm is part of the planning system and produces better plans compared to those produced using a well-known scoring-based algorithm. Our algorithm is very efficient and finds the beam configuration at least ten times faster than an exact integer programming approach. Solution times range from 2 minutes to 15 minutes which is clinically acceptable. With certain cancers, especially lung cancer, a patient's anatomy changes during treatment. These anatomical changes need to be considered in treatment planning. Fortunately, recent advances in imaging technology can provide multiple images of the treatment region taken at different points of the breathing cycle, and deformable image registration algorithms can

  11. Coupled External Cavity Photonic Crystal Enhanced Fluorescence

    PubMed Central

    Pokhriyal, Anusha; Lu, Meng; Ge, Chun; Cunningham, Brian T.

    2016-01-01

    We report a fundamentally new approach to enhance fluorescence in which surface adsorbed fluorophore-tagged biomolecules are excited on a photonic crystal surface that functions as a narrow bandwidth and tunable mirror of an external cavity laser. This scheme leads to ~10× increase in the electromagnetic enhancement factor compared to ordinary photonic crystal enhanced fluorescence. In our experiments, the cavity automatically tunes its lasing wavelength to the resonance wavelength of the photonic crystal, ensuring optimal on-resonance coupling even in the presence of variable device parameters and variations in the density of surface-adsorbed capture molecules. We achieve ~105× improvement in the limit of detection of a fluorophore-tagged protein compared to its detection on an unpatterned glass substrate. The enhanced fluorescence signal and easy optical alignment make cavity-coupled photonic crystals a viable approach for further reducing detection limits of optically-excited light emitters that are used in biological assays. PMID:23129575

  12. Photonic water dynamically responsive to external stimuli.

    PubMed

    Sano, Koki; Kim, Youn Soo; Ishida, Yasuhiro; Ebina, Yasuo; Sasaki, Takayoshi; Hikima, Takaaki; Aida, Takuzo

    2016-01-01

    Fluids that contain ordered nanostructures with periodic distances in the visible-wavelength range, anomalously exhibit structural colours that can be rapidly modulated by external stimuli. Indeed, some fish can dynamically change colour by modulating the periodic distance of crystalline guanine sheets cofacially oriented in their fluid cytoplasm. Here we report that a dilute aqueous colloidal dispersion of negatively charged titanate nanosheets exhibits structural colours. In this 'photonic water', the nanosheets spontaneously adopt a cofacial geometry with an ultralong periodic distance of up to 675 nm due to a strong electrostatic repulsion. Consequently, the photonic water can even reflect near-infrared light up to 1,750 nm. The structural colour becomes more vivid in a magnetic flux that induces monodomain structural ordering of the colloidal dispersion. The reflective colour of the photonic water can be modulated over the entire visible region in response to appropriate physical or chemical stimuli. PMID:27572806

  13. Review of photon and proton radiotherapy for skull base tumours.

    PubMed

    Fossati, Piero; Vavassori, Andrea; Deantonio, Letizia; Ferrara, Eleonora; Krengli, Marco; Orecchia, Roberto

    2016-01-01

    An extremely large variety of benign and malignant tumours occur at skull base; these tumour lesions are in the proximity to structures deputed to relevant physiologic functions, limiting extensive surgical approaches to this body district. Most recent progresses of surgery and radiotherapy have allowed to improve local control with acceptable rates of side effects. Various photon radiotherapy techniques are employed, including 3-dimensional conformal radiotherapy, intensity modulated radiotherapy (IMRT), stereotactic radiotherapy (SRT) and brachytherapy that is manly limited to the treatment of primary or recurrent nasopharyngeal carcinoma. Proton beam radiotherapy is also extensively used thanks to its physical characteristics. Our review, focusing in particular on meningioma, chordoma, and chondrosarcoma, suggests that proton therapy plays a major role in the treatment of malignant tumours whereas photon therapy still plays a relevant role in the treatment of benign tumour lesions. PMID:27330419

  14. Bilateral Rhegmatogenous Retinal Detachment during External Beam Radiotherapy.

    PubMed

    Hidaka, Takako; Chuman, Hideki; Nao-I, Nobuhisa

    2016-01-01

    Herein, we report a case of nontraumatic bilateral rhegmatogenous retinal detachment (RRD) during external beam radiotherapy for nonocular tumor, presented as an observational case study in conjunction with a review of the relevant literature. A 65-year-old male was referred to our hospital due to bilateral RRD. He underwent a biopsy for a tumor of the left frontal lobe 4 months prior to presentation, and the tumor had been diagnosed as primary central nerve system B-cell type lymphoma. He received chemotherapy and external beam radiotherapy for 1 month. There were no traumatic episodes. Bilateral retinal detachment occurred during a series of radiotherapies. Simultaneous nontraumatic bilateral retinal detachment is rare. The effects of radiotherapy on ocular functionality, particularly in cases involving retinal adhesion and vitreous contraction, may include RRD. Thus, it is necessary to closely monitor the eyes of patients undergoing radiotherapy, particularly those undergoing surgery for retinal detachment and those with a history of photocoagulation for retinal tears, a relevant family history, or risk factors known to be associated with RRD. PMID:27462261

  15. Bilateral Rhegmatogenous Retinal Detachment during External Beam Radiotherapy

    PubMed Central

    Hidaka, Takako; Chuman, Hideki; Nao-i, Nobuhisa

    2016-01-01

    Herein, we report a case of nontraumatic bilateral rhegmatogenous retinal detachment (RRD) during external beam radiotherapy for nonocular tumor, presented as an observational case study in conjunction with a review of the relevant literature. A 65-year-old male was referred to our hospital due to bilateral RRD. He underwent a biopsy for a tumor of the left frontal lobe 4 months prior to presentation, and the tumor had been diagnosed as primary central nerve system B-cell type lymphoma. He received chemotherapy and external beam radiotherapy for 1 month. There were no traumatic episodes. Bilateral retinal detachment occurred during a series of radiotherapies. Simultaneous nontraumatic bilateral retinal detachment is rare. The effects of radiotherapy on ocular functionality, particularly in cases involving retinal adhesion and vitreous contraction, may include RRD. Thus, it is necessary to closely monitor the eyes of patients undergoing radiotherapy, particularly those undergoing surgery for retinal detachment and those with a history of photocoagulation for retinal tears, a relevant family history, or risk factors known to be associated with RRD. PMID:27462261

  16. Treatment of Retinoblastoma: The Role of External Beam Radiotherapy

    PubMed Central

    Park, Younghee

    2015-01-01

    The risk of radiotherapy-related secondary cancers in children with constitutional retinoblastoma 1 (RB1) mutations has led to reduced use of external beam radiotherapy (EBRT) for RB. Presently, tumor reduction with chemotherapy with or without focal surgery (chemosurgery) is most commonly undertaken; EBRT is avoided as much as possible and is considered only as the last treatment option prior to enucleation. Nevertheless, approximately 80% of patients are diagnosed at a locally advanced stage, and only 20-25% of early stage RB patients can be cured with a chemosurgery strategy. As a whole, chemotherapy fails in more than two-thirds of eyes with advanced stage disease, requiring EBRT or enucleation. Radiotherapy is still considered necessary for patients with large tumor(s) who are not candidates for chemosurgery but who have visual potential. When radiation therapy is indicated, the lowest possible radiation dose combined with systemic or local chemotherapy and focal surgery may yield the best clinical outcomes in terms of local control and treatment-related toxicity. Proton beam therapy is one EBRT method that can be used for treatment of RB and reduces the radiation dose delivered to the adjacent orbital bone while maintaining an adequate dose to the tumor. To maximize the therapeutic success of treatment of advanced RB, the possibility of integrating radiotherapy at early stages of treatment may need to be discussed by a multidisciplinary team, rather than considering EBRT as only a last treatment option. PMID:26446627

  17. Improving external beam radiotherapy by combination with internal irradiation

    PubMed Central

    Koi, L; Zöphel, K; Sihver, W; Kotzerke, J; Baumann, M; Krause, M

    2015-01-01

    The efficacy of external beam radiotherapy (EBRT) is dose dependent, but the dose that can be applied to solid tumour lesions is limited by the sensitivity of the surrounding tissue. The combination of EBRT with systemically applied radioimmunotherapy (RIT) is a promising approach to increase efficacy of radiotherapy. Toxicities of both treatment modalities of this combination of internal and external radiotherapy (CIERT) are not additive, as different organs at risk are in target. However, advantages of both single treatments are combined, for example, precise high dose delivery to the bulk tumour via standard EBRT, which can be increased by addition of RIT, and potential targeting of micrometastases by RIT. Eventually, theragnostic radionuclide pairs can be used to predict uptake of the radiotherapeutic drug prior to and during therapy and find individual patients who may benefit from this treatment. This review aims to highlight the outcome of pre-clinical studies on CIERT and resultant questions for translation into the clinic. Few clinical data are available until now and reasons as well as challenges for clinical implementation are discussed. PMID:25782328

  18. Photon, light ion, and heavy ion cancer radiotherapy: paths from physics and biology to clinical practice

    PubMed Central

    2015-01-01

    External beam radiotherapy has proven highly effective against a wide range of cancers, and in recent decades there have been rapid advances with traditional photon-based (X-ray) radiotherapy and the development of two particle-based techniques, proton and carbon ion radiotherapy (CIRT). There are major cost differences and both physical and biological differences among these modalities that raise important questions about relative treatment efficacy and cost-effectiveness. Randomized clinical trials (RCTs) represent the gold standard for comparing treatments, but there are significant cost and ethical barriers to their wide-spread use. Meta-analysis of non-coordinated clinical trials data is another tool that can be used to compare treatments, and while this approach has recognized limitations, it is argued that meta-analysis represents an early stage of investigation that can help inform the design of future RCTs. PMID:26734646

  19. Photon, light ion, and heavy ion cancer radiotherapy: paths from physics and biology to clinical practice.

    PubMed

    Nickoloff, Jac A

    2015-12-01

    External beam radiotherapy has proven highly effective against a wide range of cancers, and in recent decades there have been rapid advances with traditional photon-based (X-ray) radiotherapy and the development of two particle-based techniques, proton and carbon ion radiotherapy (CIRT). There are major cost differences and both physical and biological differences among these modalities that raise important questions about relative treatment efficacy and cost-effectiveness. Randomized clinical trials (RCTs) represent the gold standard for comparing treatments, but there are significant cost and ethical barriers to their wide-spread use. Meta-analysis of non-coordinated clinical trials data is another tool that can be used to compare treatments, and while this approach has recognized limitations, it is argued that meta-analysis represents an early stage of investigation that can help inform the design of future RCTs. PMID:26734646

  20. Water-equivalent dosimeter array for small-field external beam radiotherapy

    SciTech Connect

    Archambault, Louis; Beddar, A. Sam; Gingras, Luc; Lacroix, Frederic; Roy, Rene; Beaulieu, Luc

    2007-05-15

    With the increasing complexity of dose patterns external beam radiotherapy, there is a great need for new types of dosimeters. We studied the first prototype of a new dosimeter array consisting of water-equivalent plastic scintillating fibers for dose measurement in external beam radiotherapy. We found that this array allows precise, rapid dose evaluation of small photon fields. Starting with a dosimeter system constructed with a single scintillating fiber coupled to a clear optical fiber and read using a charge coupled device camera, we looked at the dosimeter's spatial resolution under small radiation fields and angular dependence. Afterward, we analyzed the camera's light collection to determine the maximum array size that could be built. Finally, we developed a prototype made of ten scintillating fiber detectors to study the behavior and precision of this system in simple dosimetric situations. The scintillation detector showed no measurable angular dependence. Comparison of the scintillation detector and a small-volume ion chamber showed agreement except for 1x1 and 0.5x5.0 cm{sup 2} fields where the output factor measured by the scintillator was higher. The actual field of view of the camera could accept more than 4000 scintillating fiber detectors simultaneously. Evaluation of the dose profile and depth dose curve using a prototype with ten scintillating fiber detectors showed precise, rapid dose evaluation even with placement of more than 75 optical fibers in the field to simulate what would happen in a larger array. We concluded that this scintillating fiber dosimeter array is a valuable tool for dose measurement in external beam radiotherapy. It possesses the qualities necessary to evaluate small and irregular fields with various incident angles such as those encountered in intensity-modulated radiotherapy, radiosurgery, and tomotherapy.

  1. Energy Modulated Photon Radiotherapy: A Monte Carlo Feasibility Study

    PubMed Central

    Zhang, Ying; Feng, Yuanming; Ming, Xin

    2016-01-01

    A novel treatment modality termed energy modulated photon radiotherapy (EMXRT) was investigated. The first step of EMXRT was to determine beam energy for each gantry angle/anatomy configuration from a pool of photon energy beams (2 to 10 MV) with a newly developed energy selector. An inverse planning system using gradient search algorithm was then employed to optimize photon beam intensity of various beam energies based on presimulated Monte Carlo pencil beam dose distributions in patient anatomy. Finally, 3D dose distributions in six patients of different tumor sites were simulated with Monte Carlo method and compared between EMXRT plans and clinical IMRT plans. Compared to current IMRT technique, the proposed EMXRT method could offer a better paradigm for the radiotherapy of lung cancers and pediatric brain tumors in terms of normal tissue sparing and integral dose. For prostate, head and neck, spine, and thyroid lesions, the EMXRT plans were generally comparable to the IMRT plans. Our feasibility study indicated that lower energy (<6 MV) photon beams could be considered in modern radiotherapy treatment planning to achieve a more personalized care for individual patient with dosimetric gains. PMID:26977413

  2. Energy Modulated Photon Radiotherapy: A Monte Carlo Feasibility Study.

    PubMed

    Zhang, Ying; Feng, Yuanming; Ming, Xin; Deng, Jun

    2016-01-01

    A novel treatment modality termed energy modulated photon radiotherapy (EMXRT) was investigated. The first step of EMXRT was to determine beam energy for each gantry angle/anatomy configuration from a pool of photon energy beams (2 to 10 MV) with a newly developed energy selector. An inverse planning system using gradient search algorithm was then employed to optimize photon beam intensity of various beam energies based on presimulated Monte Carlo pencil beam dose distributions in patient anatomy. Finally, 3D dose distributions in six patients of different tumor sites were simulated with Monte Carlo method and compared between EMXRT plans and clinical IMRT plans. Compared to current IMRT technique, the proposed EMXRT method could offer a better paradigm for the radiotherapy of lung cancers and pediatric brain tumors in terms of normal tissue sparing and integral dose. For prostate, head and neck, spine, and thyroid lesions, the EMXRT plans were generally comparable to the IMRT plans. Our feasibility study indicated that lower energy (<6 MV) photon beams could be considered in modern radiotherapy treatment planning to achieve a more personalized care for individual patient with dosimetric gains. PMID:26977413

  3. A dose comparison of proton radiotherapy and photon radiotherapy for pediatric brain tumor

    NASA Astrophysics Data System (ADS)

    Kim, S. Y.; Cho, J. H.

    2014-12-01

    The purpose of this study was to investigate the effectiveness of photon radiotherapy and to compare the dose of treatment planning between proton radiotherapy and 3D conformal radiation therapy (3D-CRT) for pediatric brain tumor patients. This study was conducted in five pediatric brain tumor patients who underwent craniospinal irradiation treatment from October 2013 to April 2014 in the hospital. The study compared organs at risk (OARs) by assessing the dose distribution of normal tissue from the proton plan and 3D-CRT. Furthermore, this study assessed the treatment plans by looking at the homogeneity index (HI) and conformity index (CI). As a result, the study revealed OARs due to the small volume proton radiotherapy dose distribution in the normal tissue. Also, by comparing HI and CI between the 3D-CRT and proton radiotherapy plan, the study found that the dose of proton radiotherapy plan was homogenized. When conducting 3D-CRT and proton radiotherapy in a dose-volume histogram comparison, the dose of distribution turned out to be low. Consequently, proton radiotherapy is used for protecting the normal tissue, and is used in tumor tissue as a homogenized dose for effective treatment.

  4. Dysprosium detector for neutron dosimetry in external beam radiotherapy

    NASA Astrophysics Data System (ADS)

    Ostinelli, A.; Berlusconi, C.; Conti, V.; Duchini, M.; Gelosa, S.; Guallini, F.; Vallazza, E.; Prest, M.

    2014-09-01

    Radiotherapy treatments with high-energy (>8 MeV) photon beams are a standard procedure in clinical practice, given the skin and near-target volumes sparing effect, the accurate penetration and the uniform spatial dose distribution. On the other hand, despite these advantages, neutrons may be produced via the photo-nuclear (γ,n) reactions of the high-energy photons with the high-Z materials in the accelerator head, in the treatment room and in the patient, resulting in an unwanted dose contribution which is of concern, given its potential to induce secondary cancers, and which has to be monitored. This work presents the design and the test of a portable Dysprosium dosimeter to be used during clinical treatments to estimate the "in vivo" dose to the patient. The dosimeter has been characterized and validated with tissue-equivalent phantom studies with a Varian Clinical iX 18 MV photon beam, before using it with a group of patients treated at the S. Anna Hospital in Como. The working principle of the dosimeter together with the readout chain and the results in terms of delivered dose are presented.

  5. Absorbed dose behind eye shields during kilovoltage photon radiotherapy.

    PubMed

    Baker, C R; Luhana, F; Thomas, S J

    2002-08-01

    The absorbed dose at the position of the lens of the eye under lead or tungsten eye shields during kilovoltage photon radiotherapy is critically dependent not so much on the thickness of the eye shield itself as on the size of the treatment field and the diameter of the shield used. Whilst dose from primary photons is easily attenuated to relatively insignificant levels by a few millimetres of lead or tungsten, scattered photons from outside the shielded area can provide over 25% of the prescribed dose. Since backscatter factors do not increase monotonically with photon energy, it is not safe to assume that the highest photon energy used will provide the highest dose. A simple method to estimate the dose under an eye shield based on tabulated backscatter factors is shown. Measurements under commercially available eye shields were made to verify the expression and to determine the attenuation of primary photons. Predicted and measured absorbed dose under the eye shields were found to agree to within 1% of the prescribed dose. The relative dose due to primary photons beneath the eye shields was found to be less than 0.1% and 0.5 (+/-0.1)% for the 150 kV and 260 kV beams, respectively. This is considerably less than the dose from backscattered radiation. PMID:12153943

  6. Excellent Local Control With Stereotactic Radiotherapy Boost After External Beam Radiotherapy in Patients With Nasopharyngeal Carcinoma

    SciTech Connect

    Hara, Wendy; Loo, Billy W.; Goffinet, Don R.; Chang, Steven D.; Adler, John R.; Pinto, Harlan A.; Fee, Willard E.; Kaplan, Michael J.; Fischbein, Nancy J.; Le, Quynh-Thu

    2008-06-01

    Purpose: To determine long-term outcomes in patients receiving stereotactic radiotherapy (SRT) as a boost after external beam radiotherapy (EBRT) for locally advanced nasopharyngeal carcinoma (NPC). Methods and Materials: Eight-two patients received an SRT boost after EBRT between September 1992 and July 2006. Nine patients had T1, 30 had T2, 12 had T3, and 31 had T4 tumors. Sixteen patients had Stage II, 19 had Stage III, and 47 had Stage IV disease. Patients received 66 Gy of EBRT followed by a single-fraction SRT boost of 7-15 Gy, delivered 2-6 weeks after EBRT. Seventy patients also received cisplatin-based chemotherapy delivered concurrently with and adjuvant to radiotherapy. Results: At a median follow-up of 40.7 months (range, 6.5-144.2 months) for living patients, there was only 1 local failure in a patient with a T4 tumor. At 5 years, the freedom from local relapse rate was 98%, freedom from nodal relapse 83%, freedom from distant metastasis 68%, freedom from any relapse 67%, and overall survival 69%. Late toxicity included radiation-related retinopathy in 3, carotid aneurysm in 1, and radiographic temporal lobe necrosis in 10 patients, of whom 2 patients were symptomatic with seizures. Of 10 patients with temporal lobe necrosis, 9 had T4 tumors. Conclusion: Stereotactic radiotherapy boost after EBRT provides excellent local control for patients with NPC. Improved target delineation and dose homogeneity of radiation delivery for both EBRT and SRT is important to avoid long-term complications. Better systemic therapies for distant control are needed.

  7. [Biochemical recurrence criteria after radiotherapy (external beam, brachytherapy). Natural history of the disease after radiotherapy].

    PubMed

    Villoslada, Carmen Ibáñez; Olombrada, Maria Victoria de Torres; San Segundo, Carmen González

    2012-01-01

    Prostate specific antigen (PSA) is the main tool in the follow-up of prostate cancer patients after definitive therapy. It's widely used as an early marker to value treatment success. Biochemical recurrence predicts metastatic disease progression and prostate cancer-specific mortality. In 1996, the American Society for Therapeutic Radiology and Oncology (ASTRO) provided a definition of biochemical failure after radiotherapy, based on three consecutive increases in PSA after nadir. As more experience was gained using the proposed definition and follow up duration in the PSA era matured, deficiencies and controversial issues emerged, so more recently proposed candidate definitions have provided consistent outcome. In view of the criticisms, a second consensus conference was held on 2005, with "nadir + 2 ng/ml" accepted as standard definition. The natural history and evidence of PSA kinetic parameters and different definitions of biochemical failure after external beam radiation therapy and/or brachytherapy are reviewed in the following article. PMID:22318174

  8. Technical advances in external radiotherapy for hepatocellular carcinoma

    PubMed Central

    Park, Shin-Hyung; Kim, Jae-Chul; Kang, Min Kyu

    2016-01-01

    Radiotherapy techniques have substantially improved in the last two decades. After the introduction of 3-dimensional conformal radiotherapy, radiotherapy has been increasingly used for the treatment of hepatocellular carcinoma (HCC). Currently, more advanced techniques, including intensity-modulated radiotherapy (IMRT), stereotactic ablative body radiotherapy (SABR), and charged particle therapy, are used for the treatment of HCC. IMRT can escalate the tumor dose while sparing the normal tissue even though the tumor is large or located near critical organs. SABR can deliver a very high radiation dose to small HCCs in a few fractions, leading to high local control rates of 84%-100%. Various advanced imaging modalities are used for radiotherapy planning and delivery to improve the precision of radiotherapy. These advanced techniques enable the delivery of high dose radiotherapy for early to advanced HCCs without increasing the radiation-induced toxicities. However, as there have been no effective tools for the prediction of the response to radiotherapy or recurrences within or outside the radiation field, future studies should focus on selecting the patients who will benefit from radiotherapy. PMID:27621577

  9. Technical advances in external radiotherapy for hepatocellular carcinoma.

    PubMed

    Park, Shin-Hyung; Kim, Jae-Chul; Kang, Min Kyu

    2016-08-28

    Radiotherapy techniques have substantially improved in the last two decades. After the introduction of 3-dimensional conformal radiotherapy, radiotherapy has been increasingly used for the treatment of hepatocellular carcinoma (HCC). Currently, more advanced techniques, including intensity-modulated radiotherapy (IMRT), stereotactic ablative body radiotherapy (SABR), and charged particle therapy, are used for the treatment of HCC. IMRT can escalate the tumor dose while sparing the normal tissue even though the tumor is large or located near critical organs. SABR can deliver a very high radiation dose to small HCCs in a few fractions, leading to high local control rates of 84%-100%. Various advanced imaging modalities are used for radiotherapy planning and delivery to improve the precision of radiotherapy. These advanced techniques enable the delivery of high dose radiotherapy for early to advanced HCCs without increasing the radiation-induced toxicities. However, as there have been no effective tools for the prediction of the response to radiotherapy or recurrences within or outside the radiation field, future studies should focus on selecting the patients who will benefit from radiotherapy. PMID:27621577

  10. External Beam Radiotherapy for Colon Cancer: Patterns of Care

    SciTech Connect

    Dunn, Emily F.; Kozak, Kevin R.; Moody, John S.

    2010-04-15

    Purpose: Despite its common and well characterized use in other gastrointestinal malignancies, little is known about radiotherapy (RT) use in nonmetastatic colon cancer in the United States. To address the paucity of data regarding RT use in colon cancer management, we examined the RT patterns of care in this patient population. Methods and Materials: Patients with nonmetastatic colon cancer, diagnosed between 1988 and 2005, were identified in the Surveillance, Epidemiology, and End Results (SEER) database. Univariate and multivariate methods were used to identify factors associated with RT use. Results: On univariate analysis, tumor location, age, sex, race, T stage, N stage, and geographic location were each associated with differences in RT use (all p < 0.01). In general, younger patients, male patients, and patients with more advanced disease were more likely to receive RT. On multivariate analysis, tumor location, age, gender, T and N stage, time of diagnosis and geographic location were significantly associated with RT use (all p < 0.001). Race, however, was not associated with RT use. On multivariate analysis, patients diagnosed in 1988 were 2.5 times more likely to receive RT than those diagnosed in 2005 (p = 0.001). Temporal changes in RT use reflect a responsiveness to evolving evidence related to the therapeutic benefits of adjuvant RT. Conclusions: External beam RT is infrequently used for colon cancer, and its use varies according to patient and tumor characteristics. RT use has declined markedly since the late 1980s; however, it continues to be used for nonmetastatic disease in a highly individualized manner.

  11. Characterization of a computed radiography system for external radiotherapy beam dosimetry.

    PubMed

    Aberle, Christoph; Kapsch, Ralf-Peter

    2016-06-01

    A commercial computed radiography (CR) system was studied as an option for quantitative dosimetry quality assurance of external radiotherapy beams. Following the examination of influencing quantities, practical measurement procedures are discussed. Corrections were derived for image fading, an observed long-term response drift and the image length scale, which was found to be off by up to 2-3%. It is known that energy dependence is important for CR measurements. Therefore, signal-to-dose calibration curves and the energy dependence of the response were studied extensively using multiple photon and electron beam qualities. Doses which yield the same signal vary by up to tens of percent for different beam qualities. Results on the directional response of the plates are presented. It was found that rotations of up to 30° to 40° relative to perpendicular irradiation yield no significant change in response. Finally, the homogeneity of the response over the measurement region was studied for electrons and photons and a correction method is described. In summary, relative dose measurements with uncertainties of a few percent are feasible in regions of constant beam energy. PMID:27163755

  12. Characterization of a computed radiography system for external radiotherapy beam dosimetry

    NASA Astrophysics Data System (ADS)

    Aberle, Christoph; Kapsch, Ralf-Peter

    2016-06-01

    A commercial computed radiography (CR) system was studied as an option for quantitative dosimetry quality assurance of external radiotherapy beams. Following the examination of influencing quantities, practical measurement procedures are discussed. Corrections were derived for image fading, an observed long-term response drift and the image length scale, which was found to be off by up to 2–3%. It is known that energy dependence is important for CR measurements. Therefore, signal-to-dose calibration curves and the energy dependence of the response were studied extensively using multiple photon and electron beam qualities. Doses which yield the same signal vary by up to tens of percent for different beam qualities. Results on the directional response of the plates are presented. It was found that rotations of up to 30° to 40° relative to perpendicular irradiation yield no significant change in response. Finally, the homogeneity of the response over the measurement region was studied for electrons and photons and a correction method is described. In summary, relative dose measurements with uncertainties of a few percent are feasible in regions of constant beam energy.

  13. Peripheral photon and neutron doses from prostate cancer external beam irradiation.

    PubMed

    Bezak, Eva; Takam, Rundgham; Marcu, Loredana G

    2015-12-01

    Peripheral photon and neutron doses from external beam radiotherapy (EBRT) are associated with increased risk of carcinogenesis in the out-of-field organs; thus, dose estimations of secondary radiation are imperative. Peripheral photon and neutron doses from EBRT of prostate carcinoma were measured in Rando phantom. (6)LiF:Mg,Cu,P and (7)LiF:Mg,Cu,P glass-rod thermoluminescence dosemeters (TLDs) were inserted in slices of a Rando phantom followed by exposure to 80 Gy with 18-MV photon four-field 3D-CRT technique. The TLDs were calibrated using 6- and 18-MV X-ray beam. Neutron dose equivalents measured with CR-39 etch-track detectors were used to derive readout-to-neutron dose conversion factor for (6)LiF:Mg,Cu,P TLDs. Average neutron dose equivalents per 1 Gy of isocentre dose were 3.8±0.9 mSv Gy(-1) for thyroid and 7.0±5.4 mSv Gy(-1) for colon. For photons, the average dose equivalents per 1 Gy of isocentre dose were 0.2±0.1 mSv Gy(-1) for thyroid and 8.1±9.7 mSv Gy(-1) for colon. Paired (6)LiF:Mg,Cu,P and (7)LiF:Mg,Cu,P TLDs can be used to measure photon and neutron doses simultaneously. Organs in close proximity to target received larger doses from photons than those from neutrons whereas distally located organs received higher neutron versus photon dose. PMID:25564673

  14. Salivary Gland. Photon beam and particle radiotherapy: Present and future.

    PubMed

    Orlandi, Ester; Iacovelli, Nicola Alessandro; Bonora, Maria; Cavallo, Anna; Fossati, Piero

    2016-09-01

    Salivary gland cancers (SGCs) are rare diseases and their treatment depends upon histology, stage and site of origin. Radical surgery is the mainstay of treatment but radiotherapy (RT) plays a key role in both the postoperative and the inoperable setting, as well as in recurrent disease. In the absence of prospective randomized trials, a wide retrospective literature suggests postoperative RT (PORT) in patients with high risk pathological features. SGCs, and adenoid cystic carcinoma (ACC) in particular, are known to be radio-resistant tumors and should therefore respond well to particle beam therapy. Recently, excellent outcome has been reported with radical carbon ion RT (CIRT) in particular for ACC. Both modern photon- and hadron-based treatments are effective and are characterized by a favourable toxicity profile. But it is not clear whether one modality is superior to the other for disease control, due to the differences in patients' selection, techniques, fractionation schedules and outcome measurements among clinical experiences. In this paper, we review the role of photon and particle RT for malignant SGCs, discussing the difference between modalities in terms of biological and technical characteristics. RT dose and target volumes for different histologies (ACC versus non-ACC) have also been taken into consideration. PMID:27394087

  15. [Description of latest generation equipment in external radiotherapy].

    PubMed

    Pellejero, S; Lozares, S; Mañeru, F

    2009-01-01

    Both the planning systems and the form of administering radiotherapy have changed radically since the introduction of 3D planning. At present treatment planning based on computerised axial tomography (CAT) images is standard practice in radiotherapy services. In recent years lineal accelerators for medical use have incorporated technology capable of administering intensity modulated radiation beams (IMRT). With this mode distributions of conformed doses are generated that adjust to the three dimensional form of the white volume, providing appropriate coverage and a lower dose to nearby risk organs. The use of IMRT is rapidly spreading amongst radiotherapy centres throughout the world. This growing use of IMRT has focused attention on the need for greater control of the geometric uncertainties in positioning the patient and control of internal movements. To this end, both flat and volumetric image systems have been incorporated into the treatment equipment, making image-guided radiotherapy (IGRT) possible. This article offers a brief description of the latest advances included in the planning and administration of radiotherapy treatment. PMID:19738655

  16. Intraoperative Radiotherapy Versus Whole-Breast External Beam Radiotherapy in Early-Stage Breast Cancer

    PubMed Central

    Zhang, Li; Zhou, Zhirui; Mei, Xin; Yang, Zhaozhi; Ma, Jinli; Chen, Xingxing; Wang, Junqi; Liu, Guangyu; Yu, Xiaoli; Guo, Xiaomao

    2015-01-01

    Abstract There has not been a clear answer about the efficacy of intraoperative radiotherapy (IORT) for women with early-stage breast cancer. The aim of this meta-analysis was to summarize the available evidence comparing the efficacy and safety of IORT with those of whole-breast external beam radiotherapy (EBRT) for women with early-stage breast cancer. MEDLINE, EMBASE, the Web of Science, and the Cochrane Library were searched up to October 2014. Two authors independently conducted the literature selection and data extraction. Studies that compared IORT with whole-breast EBRT were included in the systematic review. IORT was defined as a single dose of irradiation to the tumor bed during breast-conserving surgery rather than whole-breast irradiation. Qualities of RCTs were evaluated according to the PEDro scale. Qualities of non-RCTs were evaluated according to the Methodological Index for Non-Randomized Studies (MINORS). The risk ratios (RRs) of ipsilateral breast tumor recurrence, overall mortality, breast cancer mortality, non-breast cancer mortality, and distant metastasis were pooled using a random-effects model. Four studies with 5415 patients were included in this meta-analysis, including 2 randomized controlled trials (RCTs) and 2 non-RCTs. Ipsilateral breast tumor recurrence was significantly higher in patients with IORT compared to those with whole-breast EBRT (RR 2.83, 95% CI 1.23–6.51), but with significant heterogeneity (I2 = 58.5%, P = 0.065). Comparing IORT with whole-breast EBRT, the pooled RRs for overall mortality, breast cancer mortality, non-breast cancer mortality, and distant metastasis were 0.88 (95% CI: 0.66–1.17), 1.20 (95% CI: 0.77–1.86), 0.76 (95% CI: 0.44–1.31), and 0.95 (95% CI: 0.61–1.49), respectively. IORT had a significantly higher risk of ipsilateral breast tumor recurrence than whole-breast EBRT. Overall mortality did not differ significantly. IORT should be used in conjunction with the prudent selection of

  17. Intensity modulated neutron radiotherapy optimization by photon proxy

    SciTech Connect

    Snyder, Michael; Hammoud, Ahmad; Bossenberger, Todd; Spink, Robyn; Burmeister, Jay

    2012-08-15

    Purpose: Introducing intensity modulation into neutron radiotherapy (IMNRT) planning has the potential to mitigate some normal tissue complications seen in past neutron trials. While the hardware to deliver IMNRT plans has been in use for several years, until recently the IMNRT planning process has been cumbersome and of lower fidelity than conventional photon plans. Our in-house planning system used to calculate neutron therapy plans allows beam weight optimization of forward planned segments, but does not provide inverse optimization capabilities. Commercial treatment planning systems provide inverse optimization capabilities, but currently cannot model our neutron beam. Methods: We have developed a methodology and software suite to make use of the robust optimization in our commercial planning system while still using our in-house planning system to calculate final neutron dose distributions. Optimized multileaf collimator (MLC) leaf positions for segments designed in the commercial system using a 4 MV photon proxy beam are translated into static neutron ports that can be represented within our in-house treatment planning system. The true neutron dose distribution is calculated in the in-house system and then exported back through the MATLAB software into the commercial treatment planning system for evaluation. Results: The planning process produces optimized IMNRT plans that reduce dose to normal tissue structures as compared to 3D conformal plans using static MLC apertures. The process involves standard planning techniques using a commercially available treatment planning system, and is not significantly more complex than conventional IMRT planning. Using a photon proxy in a commercial optimization algorithm produces IMNRT plans that are more conformal than those previously designed at our center and take much less time to create. Conclusions: The planning process presented here allows for the optimization of IMNRT plans by a commercial treatment planning

  18. Improving the neutron-to-photon discrimination capability of detectors used for neutron dosimetry in high energy photon beam radiotherapy.

    PubMed

    Irazola, L; Terrón, J A; Bedogni, R; Pola, A; Lorenzoli, M; Sánchez-Nieto, B; Gómez, F; Sánchez-Doblado, F

    2016-09-01

    The increasing interest of the medical community to radioinduced second malignancies due to photoneutrons in patients undergoing high-energy radiotherapy, has stimulated in recent years the study of peripheral doses, including the development of some dedicated active detectors. Although these devices are designed to respond to neutrons only, their parasitic photon response is usually not identically zero and anisotropic. The impact of these facts on measurement accuracy can be important, especially in points close to the photon field-edge. A simple method to estimate the photon contribution to detector readings is to cover it with a thermal neutron absorber with reduced secondary photon emission, such as a borated rubber. This technique was applied to the TNRD (Thermal Neutron Rate Detector), recently validated for thermal neutron measurements in high-energy photon radiotherapy. The positive results, together with the accessibility of the method, encourage its application to other detectors and different clinical scenarios. PMID:27337649

  19. Kilovoltage Rotational External Beam Radiotherapy on a Breast Computed Tomography Platform: A Feasibility Study

    SciTech Connect

    Prionas, Nicolas D.; McKenney, Sarah E.; Stern, Robin L.; Boone, John M.

    2012-10-01

    Purpose: To demonstrate the feasibility of a dedicated breast computed tomography (bCT) platform to deliver rotational kilovoltage (kV) external beam radiotherapy (RT) for partial breast irradiation, whole breast irradiation, and dose painting. Methods and Materials: Rotational kV-external beam RT using the geometry of a prototype bCT platform was evaluated using a Monte Carlo simulator. A point source emitting 178 keV photons (approximating a 320-kVp spectrum with 4-mm copper filtration) was rotated around a 14-cm voxelized polyethylene disk (0.1 cm tall) or cylinder (9 cm tall) to simulate primary and primary plus scattered photon interactions, respectively. Simulations were also performed using voxelized bCT patient images. Beam collimation was varied in the x-y plane (1-14 cm) and in the z-direction (0.1-10 cm). Dose painting for multiple foci, line, and ring distributions was demonstrated using multiple rotations with varying beam collimation. Simulations using the scanner's native hardware (120 kVp filtered by 0.2-mm copper) were validated experimentally. Results: As the x-y collimator was narrowed, the two-dimensional dose profiles shifted from a cupped profile with a high edge dose to an increasingly peaked central dose distribution with a sharp dose falloff. Using a 1-cm beam, the cylinder edge dose was <7% of the dose deposition at the cylinder center. Simulations using 120-kVp X-rays showed distributions similar to the experimental measurements. A homogeneous dose distribution (<2.5% dose fluctuation) with a 20% decrease in dose deposition at the cylinder edge (i.e., skin sparing) was demonstrated by weighted summation of four dose profiles using different collimation widths. Simulations using patient bCT images demonstrated the potential for treatment planning and image-guided RT. Conclusions: Rotational kV-external beam RT for partial breast irradiation, dose painting, and whole breast irradiation with skin sparing is feasible on a bCT platform with

  20. Hypofractionated External-Beam Radiotherapy for Prostate Cancer

    PubMed Central

    Cho, L. Chinsoo; Timmerman, Robert; Kavanagh, Brian

    2013-01-01

    There are radiobiological rationales supporting hypofractionated radiotherapy for prostate cancer. The recent advancements in treatment planning and delivery allow sophisticated radiation treatments to take advantage of the differences in radiobiology of prostate cancer and the surrounding normal tissues. The preliminary results from clinical studies indicate that abbreviated fractionation programs can result in successful treatment of localized prostate cancer without escalation of late toxicity. PMID:23533777

  1. Variation in Adherence to External Beam Radiotherapy Quality Measures Among Elderly Men With Localized Prostate Cancer

    SciTech Connect

    Bekelman, Justin E. Zelefsky, Michael J.; Jang, Thomas L.; Basch, Ethan M.; Schrag, Deborah

    2007-12-01

    Purpose: To characterize the variation in adherence to quality measures of external beam radiotherapy (EBRT) for localized prostate cancer and its relation to patient and provider characteristics in a population-based, representative sample of U.S. men. Methods and Materials: We evaluated EBRT quality measures proposed by a RAND expert panel of physicians among men aged {>=}65 years diagnosed between 2000 and 2002 with localized prostate cancer and treated with primary EBRT using data from the linked Surveillance, Epidemiology, and End Results (SEER)-Medicare program. We assessed the adherence to five EBRT quality measures that were amenable to analysis using SEER-Medicare data: (1) use of conformal RT planning; (2) use of high-energy (>10-MV) photons; (3) use of custom immobilization; (4) completion of two follow-up visits with a radiation oncologist in the year after therapy; and (5) radiation oncologist board certification. Results: Of the 11,674 patients, 85% had received conformal RT planning, 75% had received high-energy photons, and 97% had received custom immobilization. One-third of patients had completed two follow-up visits with a radiation oncologist, although 91% had at least one visit with a urologist or radiation oncologist. Most patients (85%) had been treated by a board-certified radiation oncologist. Conclusions: The overall high adherence to EBRT quality measures masked substantial variation in geography, socioeconomic status in the area of residence, and teaching affiliation of the RT facility. Future research should examine the reasons for the variations in these measures and whether the variation is associated with important clinical outcomes.

  2. External Beam Radiotherapy for Prostate Cancer Patients on Anticoagulation Therapy: How Significant is the Bleeding Toxicity?

    SciTech Connect

    Choe, Kevin S.; Jani, Ashesh B.; Liauw, Stanley L.

    2010-03-01

    Purpose: To characterize the bleeding toxicity associated with external beam radiotherapy for prostate cancer patients receiving anticoagulation (AC) therapy. Methods and Materials: The study cohort consisted of 568 patients with adenocarcinoma of the prostate who were treated with definitive external beam radiotherapy. Of these men, 79 were receiving AC therapy with either warfarin or clopidogrel. All patients were treated with three-dimensional conformal radiotherapy or intensity-modulated radiotherapy. Bleeding complications were recorded during treatment and subsequent follow-up visits. Results: With a median follow-up of 48 months, the 4-year actuarial risk of Grade 3 or worse bleeding toxicity was 15.5% for those receiving AC therapy compared with 3.6% among those not receiving AC (p < .0001). On multivariate analysis, AC therapy was the only significant factor associated with Grade 3 or worse bleeding (p < .0001). For patients taking AC therapy, the crude rate of bleeding was 39.2%. Multivariate analysis within the AC group demonstrated that a higher radiotherapy dose (p = .0408), intensity-modulated radiotherapy (p = 0.0136), and previous transurethral resection of the prostate (p = .0001) were associated with Grade 2 or worse bleeding toxicity. Androgen deprivation therapy was protective against bleeding, with borderline significance (p = 0.0599). Dose-volume histogram analysis revealed that Grade 3 or worse bleeding was minimized if the percentage of the rectum receiving >=70 Gy was <10% or the rectum receiving >=50 Gy was <50%. Conclusion: Patients taking AC therapy have a substantial risk of bleeding toxicity from external beam radiotherapy. In this setting, dose escalation or intensity-modulated radiotherapy should be used judiciously. With adherence to strict dose-volume histogram criteria and minimizing hotspots, the risk of severe bleeding might be reduced.

  3. Analysis of errors detected in external beam audit dosimetry program at Mexican radiotherapy centers

    NASA Astrophysics Data System (ADS)

    Álvarez-Romero, José T.; Tovar-Muñoz, Víctor M.

    2012-10-01

    Presented and analyzed are the causes of deviation observed in the pilot postal dosimetry audit program to verify the absorbed dose to water Dw in external beams of teletherapy 60Co and/or linear accelerators in Mexican radiotherapy centers, during the years 2007-2011.

  4. On beam quality and flatness of radiotherapy megavoltage photon beams

    PubMed Central

    Hossain, Murshed; Rhoades, Jeffrey

    2015-01-01

    Ratio of percentage depth dose (PDD) at two depths, PDD at a depth of 10 cm (PDD10), and beam flatness are monitored regularly for radiotherapy beams for quality assurance. The purpose of this study is to understand the effects of changes in one of these parameters on the other. Is it possible to monitor only the beam flatness and not PDD? The investigation has two components. Naturally occurring i.e., unintended changes in PDD ratio and in-plane flatness for 6 and 10 MV photon beams for one particular Siemens Artiste Linac are monitored for a period of about 4 years. Secondly, deliberate changes in the beam parameters are induced by changing the bending magnet current (BMI). Relationships between various beam parameters for unintended changes as well as deliberate changes are characterized. Long term unintentional changes of PDD ratio are found to have no systematic trend. The flatness in the inplane direction for 6 and 10 MV beams show slow increase of 0.43% and 0.75% respectively in about 4 years while the changes in the PDD ratio show no such trend. Over 10% changes in BMI are required to induce changes in the beam quality indices at 2% level. PDD ratio for the 10 MV beam is found to be less sensitive, while the depth of maximum dose, dmax, is more sensitive to the changes in BMI compared to the 6 MV beam. Tolerances are more stringent for PDD10 than PDD ratio for the 10 MV beam. PDD ratio, PDD10, and flatness must be monitored independently. Furthermore, off axis ratio alone cannot be used to monitor flatness. The effect of beam quality change in the absolute dose is clinically insignificant. PMID:26634604

  5. Prostate-specific antigen kinetics following hypofractionated stereotactic body radiotherapy boost as post-external beam radiotherapy versus conventionally fractionated external beam radiotherapy for localized prostate cancer

    PubMed Central

    Phak, Jeong Hoon; Kim, Hun Jung; Kim, Woo Chul

    2015-01-01

    Background Stereotactic body radiotherapy (SBRT) has emerged as an effective treatment for localized prostate cancer. The purpose of this study was to compare the prostate-specific antigen (PSA) kinetics between conventionally fractionated external beam radiotherapy (CF-EBRT) and SBRT boost after whole pelvis EBRT (WP-EBRT) in localized prostate cancer. Methods A total of 77 patients with localized prostate cancer [T-stage, T1–T3; Gleason score (GS) 5–9; PSA < 20 ng/mL] were enrolled. A total of 35 patients were treated with SBRT boost (21 Gy in 3 fractions) after WP-EBRT and 42 patients were treated with CF-EBRT (45 Gy WP-EBRT and boost of 25.2–30.6 Gy in 1.8-Gy fractions). PSA nadir and rate of change in PSA (slope) were calculated and compared. Results With a median follow-up of 52.4 months (range, 14–74 months), the median PSA nadir and slope for SBRT boost were 0.29 ng/mL and −0.506, −0.235, −0.129, and −0.092 ng/mL/mo, respectively, for durations of 1 year, 2 years, 3 years, and 4 years postradiotherapy. Similarly, for CF-EBRT, the median PSA nadir and slopes were 0.39 ng/mL and −0.720 ng/mL/mo, −0.204 ng/mL/mo, −0.121 ng/mL/mo, and −0.067 ng/mL/mo, respectively. The slope of CF-EBRT was significantly different with a greater median rate of change for 1 year postradiotherapy than that of SBRT boost (P = 0.018). Contrastively, the slopes of SBRT boost for durations of 2 years, 3 years, and 4 years tended to be continuously greater than that of CF-EBRT. The significantly lower PSA nadir was observed in SBRT boost (median nadir 0.29 ng/mL) compared with CF-EBRT (median nadir 0.35 ng/mL, P = 0.025). Five-year biochemical failure (BCF) free survival was 94.3% for SBRT boost and 78.6% for CF-EBRT (P = 0.012). Conclusion Patients treated with SBRT boost after WP-EBRT experienced a lower PSA nadir and there tended to be a continuously greater rate of decline of PSA for durations of 2 years, 3 years, and

  6. Development of silicon monolithic arrays for dosimetry in external beam radiotherapy

    NASA Astrophysics Data System (ADS)

    Bisello, Francesca; Menichelli, David; Scaringella, Monica; Talamonti, Cinzia; Zani, Margherita; Bucciolini, Marta; Bruzzi, Mara

    2015-10-01

    New tools for dosimetry in external beam radiotherapy have been developed during last years in the framework of the collaboration among the University of Florence, INFN Florence and IBA Dosimetry. The first step (in 2007) was the introduction in dosimetry of detector solutions adopted from high energy physics, namely epitaxial silicon as the base detector material and a guard ring in diode design. This allowed obtaining state of the art radiation hardness, in terms of sensitivity dependence on accumulated dose, with sensor geometry particularly suitable for the production of monolithic arrays with modular design. Following this study, a 2D monolithic array has been developed, based on 6.3×6.3 cm2 modules with 3 mm pixel pitch. This prototype has been widely investigated and turned out to be a promising tool to measure dose distributions of small and IMRT fields. A further linear array prototype has been recently design with improve spatial resolution (1 mm pitch) and radiation hardness. This 24 cm long device is constituted by 4×64 mm long modules. It features low sensitivity changes with dose (0.2%/kGy) and dose per pulse (±1% in the range 0.1-2.3 mGy/pulse, covering applications with flattened and unflattened photon fields). The detector has been tested with very satisfactory results as a tool for quality assurance of linear accelerators, with special regards to small fields, and proton pencil beams. In this contribution, the characterization of the linear array with unflattened MV X-rays, 60Co radiation and 226 MeV protons is reported.

  7. Injectable silver nanosensors: in vivo dosimetry for external beam radiotherapy using positron emission tomography

    NASA Astrophysics Data System (ADS)

    Christensen, A. N.; Rydhög, J. S.; Søndergaard, R. V.; Andresen, T. L.; Holm, S.; Munck Af Rosenschöld, P.; Conradsen, K.; Jølck, R. I.

    2016-05-01

    Development of safe and efficient radiotherapy routines requires quantification of the delivered absorbed dose to the cancer tissue in individual patients. In vivo dosimetry can provide accurate information about the absorbed dose delivered during treatment. In the current study, a novel silver-nanosensor formulation based on poly(vinylpyrrolidinone)-coated silver nanoparticles formulated in a gelation matrix composed of sucrose acetate isobutyrate has been developed for use as an in vivo dosimeter for external beam radiotherapy. In situ photonuclear reactions trigger the formation of radioactive 106Ag, which enables post treatment verification of the delivered dose using positron emission tomography imaging. The silver-nanosensor was investigated in a tissue equivalent thorax phantom using clinical settings and workflow for both standard fractionated radiotherapy (2 Gy) and stereotactic radiotherapy (10- and 22 Gy) in a high-energy beam setting (18 MV). The developed silver-nanosensor provided high radiopacity on the planning CT-scans sufficient for patient positioning in image-guided radiotherapy and provided dosimetric information about the absorbed dose with a 10% and 8% standard deviation for the stereotactic regimens, 10 and 22 Gy, respectively.Development of safe and efficient radiotherapy routines requires quantification of the delivered absorbed dose to the cancer tissue in individual patients. In vivo dosimetry can provide accurate information about the absorbed dose delivered during treatment. In the current study, a novel silver-nanosensor formulation based on poly(vinylpyrrolidinone)-coated silver nanoparticles formulated in a gelation matrix composed of sucrose acetate isobutyrate has been developed for use as an in vivo dosimeter for external beam radiotherapy. In situ photonuclear reactions trigger the formation of radioactive 106Ag, which enables post treatment verification of the delivered dose using positron emission tomography imaging. The

  8. Triple course external beam radiotherapy for carcinoma of the prostate

    SciTech Connect

    El-Mahdi, A.M.; Turalba, C.I.C.; Schellhammer, P.F.; Peeples, W.J.

    1984-04-01

    In 1976 this hospital began using a triple-course technique of external beam irradiation for localized carcinoma of the prostate. The treatment consisted of 2 courses of 20 Gy in 2 weeks to the pelvis and a third course of 20-25 Gy in 2-2 1/2 weeks as a boost to the prostate. A 2 week rest followed the first and second courses. The results of this treatment technique are reported on the first 50 patients who had been followed for at least 3 years. Although 96% of these patients developed bladder and/or bowel reactions, the majority of the symptoms were in the very mild to mild category, with only 2% severe reactions referrable to each organ. The incidence of late complications in this series compared favorably to those reported by other authors. Clinical local control was 96% while postreatment needle biopsy performed on 22/50 patients yielded a negative rate of 86%. This study has shown that with triple course external beam irradiation, excellent control of localized carcinoma of the prostate can be achieved with minimal acute morbidity.

  9. Salvage brachytherapy for locally recurrent prostate cancer after external beam radiotherapy.

    PubMed

    Yamada, Yasuhiro; Okihara, Koji; Iwata, Tsuyoshi; Masui, Koji; Kamoi, Kazumi; Yamada, Kei; Miki, Tsuneharu

    2015-01-01

    External beam radiotherapy (EBRT) is a standard treatment for prostate cancer. Despite the development of novel radiotherapy techniques such as intensity-modulated conformal radiotherapy, the risk of local recurrence after EBRT has not been obviated. Various local treatment options (including salvage prostatectomy, brachytherapy, cryotherapy, and high-intensity focused ultrasound [HIFU]) have been employed in cases of local recurrence after primary EBRT. Brachytherapy is the first-line treatment for low-risk and selected intermediate-risk prostate tumors. However, few studies have examined the use of brachytherapy to treat post-EBRT recurrent prostate cancer. The purpose of this paper is to analyze the current state of our knowledge about the effects of salvage brachytherapy in patients who develop locally recurrent prostate cancer after primary EBRT. This article also introduces our novel permanent brachytherapy salvage method. PMID:26112477

  10. Injectable silver nanosensors: in vivo dosimetry for external beam radiotherapy using positron emission tomography.

    PubMed

    Christensen, A N; Rydhög, J S; Søndergaard, R V; Andresen, T L; Holm, S; Munck Af Rosenschöld, P; Conradsen, K; Jølck, R I

    2016-06-01

    Development of safe and efficient radiotherapy routines requires quantification of the delivered absorbed dose to the cancer tissue in individual patients. In vivo dosimetry can provide accurate information about the absorbed dose delivered during treatment. In the current study, a novel silver-nanosensor formulation based on poly(vinylpyrrolidinone)-coated silver nanoparticles formulated in a gelation matrix composed of sucrose acetate isobutyrate has been developed for use as an in vivo dosimeter for external beam radiotherapy. In situ photonuclear reactions trigger the formation of radioactive (106)Ag, which enables post treatment verification of the delivered dose using positron emission tomography imaging. The silver-nanosensor was investigated in a tissue equivalent thorax phantom using clinical settings and workflow for both standard fractionated radiotherapy (2 Gy) and stereotactic radiotherapy (10- and 22 Gy) in a high-energy beam setting (18 MV). The developed silver-nanosensor provided high radiopacity on the planning CT-scans sufficient for patient positioning in image-guided radiotherapy and provided dosimetric information about the absorbed dose with a 10% and 8% standard deviation for the stereotactic regimens, 10 and 22 Gy, respectively. PMID:27174233

  11. External beam radiotherapy for palliation of pain from metastatic carcinoma of the prostate

    SciTech Connect

    Benson, R.C. Jr.; Hasan, S.M.; Jones, A.G.; Schlise, S.

    1982-01-01

    Radiotherapy often is used for palliation of bone pain from metastatic cancer of the prostate but an objective evaluation of its efficacy in a large series of patients is unavailable. We report the results of external beam irradiation in 62 patients who had bone pain secondary to stage D carcinoma of the prostate. The variables used to judge pain before and after radiotherapy included subjective evaluation of pain, status of activity and quantitation of analgesic use. Complete relief of pain was achieved in 26 patients (42 per cent), partial relief in 22 (35 per cent) and no relief in 14 (23 per cent). On the basis of our experience external beam irradiation is useful palliative therapy for pain from metastatic cancer of the prostate.

  12. Effect of external shielding for neutrons during radiotherapy for prostate cancer, considering the 2300 CD linear accelerator and voxel phantom

    NASA Astrophysics Data System (ADS)

    Thalhofer, J. L.; Roque, H. S.; Rebello, W. F.; Correa, S. A.; Silva, A. X.; Souza, E. M.; Batita, D. V. S.; Sandrini, E. S.

    2014-02-01

    Photoneutron production occurs when high energy photons, greater than 6.7 MeV, interact with linear accelerator head structures. In Brazil, the National Cancer Institute, one of the centers of reference in cancer treatment, uses radiation at 4 angles (0°, 90°, 180° and 270°) as treatment protocol for prostate cancer. With the objective of minimizing the dose deposited in the patient due to photoneutrons, this study simulated radiotherapy treatment using MCNPX, considering the most realistic environment; simulating the radiotherapy room, the Linac 2300 head, the MAX phantom and the treatment protocol with the accelerator operating at 18 MV. In an attempt to reduce the dose deposited by photoneutrons, an external shielding was added to the Linac 2300. Results show that the equivalent dose due to photoneutrons deposited in the patient diminished. The biggest reduction was seen in bone structures, such as the tibia and fibula, and mandible, at approximately 75%. Besides that, organs such as the brain, pancreas, small intestine, lungs and thyroid revealed a reduction of approximately 60%. It can be concluded that the shielding developed by our research group is efficient in neutron shielding, reducing the dose for the patient, and thus, the risk of secondary cancer, and increasing patient survival rates.

  13. Spontaneous emission control of quantum dots embedded in photonic crystals: Effects of external fields and dimension

    NASA Astrophysics Data System (ADS)

    Vaseghi, B.; Hashemi, H.

    2016-06-01

    In this paper simultaneous effects of external electric and magnetic fields and quantum confinement on the radiation properties of spherical quantum dot embedded in a photonic crystal are investigated. Under the influence of photonic band-gap, effects of external static fields and dot dimension on the amplitude and spectrum of different radiation fields emitted by the quantum dot are studied. Our results show the considerable effects of external fields and quantum confinement on the spontaneous emission of the system.

  14. Survival rates in patients with differentiated thyroid carcinoma. Influence of postoperative external radiotherapy

    SciTech Connect

    Benker, G.; Olbricht, T.; Reinwein, D.; Reiners, C.; Sauerwein, W.; Krause, U.; Mlynek, M.L.; Hirche, H. )

    1990-04-01

    Nine hundred thirty-two patients with papillary and follicular thyroid carcinomas were seen at the Departments of Medicine, Surgery, and Radiology of the University of Essen, Essen, Germany, between 1970 and 1986. In addition to standard treatment by surgery, radioactive iodine and medical thyroid stimulating hormone (TSH) suppression, 346 patients had received conventional external irradiation to the neck before referral to our institutions, whereas 586 patients had not received radiotherapy. From the follow-up data of these patients, survival rates were calculated separately for tumor Stages T1 (n = 203), T2 (n = 552), and T3/T4 (n = 277) using life-table analysis. Distribution of risk factors (histologic type of tumor, grading of malignancy, presence of distant metastases, age and sex) was similar in all groups with the one exception, that the radiotherapy patients with Stage T3/T4 were older. There was no significant difference in the life expectancy of irradiated and not irradiated patients by Breslow and Mantel-Cox tests. In Stages T1, T2, and T3/T4, 75% of the radiotherapy patients survived for 10.6 +/- 0.32, 11.5 +/- 0.61, and 6.71 +/- 0.85 years, respectively; the figures for the nonirradiated patients were 9.4 +/- 0.17, 10.8 +/- 0.37, and 6.26 +/- 0.51 years, respectively. When survival rates were calculated separately for patients with Stage T3/T4 older and younger than 40 years, there was no obvious effect of radiotherapy in the younger group, whereas in the older patients, improvement of survival by radiation just failed to reach statistical significance. In conclusion, this retrospective analysis failed to prove that survival is prolonged in patients with differentiated carcinoma by administration of conventional external radiotherapy after surgery. A benefit to older patients with locally advanced tumors has still to be demonstrated.

  15. Beam related response of in vivo diode detectors for external radiotherapy

    NASA Astrophysics Data System (ADS)

    Baci, Syrja; Telhaj, Ervis; Malkaj, Partizan

    2016-03-01

    In Vivo Dosimetry (IVD) is a set of methods used in cancer treatment clinics to determine the real dose of radiation absorbed by target volume in a patient's body. IVD has been widely implemented in radiotherapy treatment centers and is now recommended part of Quality Assurance program by many International health and radiation organizations. Because of cost and lack of specialized personnel, IVD has not been practiced as yet, in Albanian radiotherapy clinics. At Hygeia Hospital Tirana, patients are irradiated with high energy photons generated by Elekta Synergy Accelerators. We have recently started experimenting with the purpose of establishing an IVD practice at this hospital. The first set of experiments was aimed at calibration of diodes that are going to be used for IVD. PMMA, phantoms by PTW were used to calibrate p - type Si, semiconductor diode dosimeters, made by PTW Freiburg for entrance dose. Response of the detectors is affected by energy of the beam, accumulated radiation dose, dose rate, temperature, angle against the beam axis, etc. Here we present the work done for calculating calibration factor and correction factors of source to surface distance, field size, and beam incidence for the entrance dose for both 6 MV photon beam and 18 MV photon beam. Dependence of dosimeter response was found to be more pronounced with source to surface distance as compared to other variables investigated.

  16. External radiotherapy prior to thyroid cancer: A case-control study

    SciTech Connect

    Hallquist, A.; Loefroth, P.O. ); Hardell, L. )

    1993-12-01

    The aim of this investigation was to study previous radiotherapy of malignant diseases as a risk factor for thyroid cancer. By using the Swedish Cancer Registry all cases of thyroid cancer with another malignant disease at least one year previously and living within the catchment area of the hospital were traced. During 1959-1989 a total of 1056 cases of thyroid cancer were identified. Of these, 37 had had another previous malignant disease and they constituted the cases in this study. As controls four persons with at least two malignant diseases, thyroid cancer excluded, were selected for each case from the same cancer registry. Ten (27.0%) of the 37 patients with thyroid cancer as a second tumor had earlier been irradiated with the treatment dose including the thyroid gland as compared with 34 (24.5%) of the 139 control patients. Eight of the ten cases with previous irradiation of the thyroid gland had papillary cancer. The median latency was 13 years. The estimated radiation dose in the thyroid varied between 3 and 40 Gy. External radiotherapy gave a crude odds ratio of 1.1 with 95% confidence interval = 0.5-2.8 for thyroid cancer. The weighted odds ratio was calculated to 2.3 with confidence interval = 0.5-8.9. This case-control study gave a nonsignificantly increased odds ratio for thyroid cancer in patients with external radiotherapy including the thyroid gland. 26 refs., 4 tabs.

  17. Multi-photon absorption in the channeling of electrons in an external field

    NASA Astrophysics Data System (ADS)

    Yaralov, V.

    2016-07-01

    Following the methods developed for atom ionization by alternating electric field the probability of multi-photon absorption of photons of the strong external laser field by channeled electron (extraction of electron from the channel) have been calculated for different strengths of the monochromatic external field. The emission spectra of 54 MeV electron channeled in diamond crystal planes (110) are shown for different values of the resonant laser field of a frequency close to the transition frequency in the channel taking into account multi-photon absorption. It is shown that the multi-photon phenomena give some contribution to the total level width.

  18. Effects of external beam radiotherapy on endocrine function in patients with carcinoma of the prostate

    SciTech Connect

    Grigsby, P.W.; Perez, C.A.

    1986-04-01

    Serum levels of testosterone, dihydrotestosterone, and follicle-stimulating and luteinizing hormones were determined prospectively in 59 patients with carcinoma of the prostate treated curatively with external beam radiotherapy. Hormone levels were determined before the initiation of therapy and up to 2 years following completion of therapy. Testosterone levels remained unchanged but dihydrotestosterone levels decreased slightly. Follicle-stimulating and luteinizing hormone levels increased significantly during therapy and remained elevated for up to 2 years after therapy. These findings are consistent with low dose irradiation of the testis.

  19. On-chip interference of single photons from an embedded quantum dot and an external laser

    NASA Astrophysics Data System (ADS)

    Prtljaga, N.; Bentham, C.; O'Hara, J.; Royall, B.; Clarke, E.; Wilson, L. R.; Skolnick, M. S.; Fox, A. M.

    2016-06-01

    In this work, we demonstrate the on-chip two-photon interference between single photons emitted by a single self-assembled InGaAs quantum dot and an external laser. The quantum dot is embedded within one arm of an air-clad directional coupler which acts as a beam-splitter for incoming light. Photons originating from an attenuated external laser are coupled to the second arm of the beam-splitter and then combined with the quantum dot photons, giving rise to two-photon quantum interference between dissimilar sources. We verify the occurrence of on-chip Hong-Ou-Mandel interference by cross-correlating the optical signal from the separate output ports of the directional coupler. This experimental approach allows us to use a classical light source (laser) to assess in a single step the overall device performance in the quantum regime and probe quantum dot photon indistinguishability on application realistic time scales.

  20. Verification of the pure alanine in PMMA tube dosimeter applicability for dosimetry of radiotherapy photon beams: a feasibility study.

    PubMed

    Al-Karmi, Anan M; Ayaz, Ali Asghar H; Al-Enezi, Mamdouh S; Abdel-Rahman, Wamied; Dwaikat, Nidal

    2015-09-01

    Alanine dosimeters in the form of pure alanine powder in PMMA plastic tubes were investigated for dosimetry in a clinical application. Electron paramagnetic resonance (EPR) spectroscopy was used to measure absorbed radiation doses by detection of signals from radicals generated in irradiated alanine. The measurements were performed for low-dose ranges typical for single-fraction doses often used in external photon beam radiotherapy. First, the dosimeters were irradiated in a solid water phantom to establish calibration curves in the dose range from 0.3 to 3 Gy for 6 and 18 MV X-ray beams from a clinical linear accelerator. Next, the dosimeters were placed at various locations in an anthropomorphic pelvic phantom to measure the dose delivery of a conventional four-field box technique treatment plan to the pelvis. Finally, the doses measured with alanine dosimeters were compared against the doses calculated with a commercial treatment planning system (TPS). The results showed that the alanine dosimeters have a highly sensitive dose response with good linearity and no energy dependence in the dose range and photon beams used in this work. Also, a fairly good agreement was found between the in-phantom dose measurements with alanine dosimeters and the TPS dose calculations. The mean value of the ratios of measured to calculated dose values was found to be near unity. The measured points in the in-field region passed dose-difference acceptance criterion of 3% and those in the penumbral region passed distance-to-agreement acceptance criterion of 3 mm. These findings suggest that the pure alanine powder in PMMA tube dosimeter is a suitable option for dosimetry of radiotherapy photon beams. PMID:26138456

  1. Second Primary Cancer After Radiotherapy for Prostate Cancer-A SEER Analysis of Brachytherapy Versus External Beam Radiotherapy

    SciTech Connect

    Abdel-Wahab, May Reis, Isildinha M.; Hamilton, Kara

    2008-09-01

    Purpose: To determine the incidence of second primary cancers (SPCs) and radiotherapy-induced SPCs (RTSPCs). Patients and Methods: The incidence of SPCs and RTSPCs was compared among four treatment groups with locoregional prostate adenocarcinoma in the 1973-2002 Surveillance, Epidemiology, and End Results database. These groups were no radiotherapy (RT), no surgery (Group 1); external beam RT (EBRT) (Group 2); brachytherapy (Group 3); and a combination of EBRT and brachytherapy (Group 4). Results: The age-adjusted estimates of SPCs were greater with EBRT than with brachytherapy (2,178 vs. 1,901 SPCs/100,000; p = 0.025) or with the no RT, no surgery group (1,971 SPCs/100,000; p <0.0001). The age-adjusted rate of late SPC ({>=}5 years) for EBRT (2,425 SPCs/100,000) was only significantly greater (p <0.0001) than that for no RT, no surgery (1,950 SPCs/100,000). The hazard ratio adjusted for age, race/ethnicity, and grade was constant at 1.263 for EBRT compared with no RT, no surgery (p <0.0001) but varied with the length of follow-up in both the brachytherapy (0.721 at 5 years to 1.200 at 9 years) and combination (0.920 at 5 years to 1.317 at 9 years) groups. The incidence of RTSPCs was only significantly different between the no RT, no surgery group and the EBRT group, with an increase of 162 cases/100,000 or a 0.16% increased SPC risk (p = 0.023). No significant differences in the incidence of RTSPC were seen between the RT groups. Conclusion: No significant differences were seen in the incidence of RTSPCs between the RT groups. The initial smaller relative risk of overall SPCs in the brachytherapy group increased with time until the curves converged, suggesting that the effect had resulted from patient selection bias.

  2. Influence of an externally modulated photonic link on a microwave communications system

    NASA Technical Reports Server (NTRS)

    Yao, X. S.; Maleki, L.

    1994-01-01

    We analyze the influence of an externally modulated photonic link on the performance of a microwave communications system. From the analysis, we deduce limitations on the photocurrent, magnitude of the relaxation oscillation noise of the laser, third-order intercept point of the preamplifier, and other parameters in order for the photonic link to function according to the system specifications. Based on this, we outline a procedure for designing a photonic link that can be integrated in a system with minimal performance degradation.

  3. Proton radiotherapy for orbital rhabdomyosarcoma: Clinical outcome and a dosimetric comparison with photons

    SciTech Connect

    Yock, Torunn . E-mail: tyock@partners.org; Schneider, Robert C.; Friedmann, Alison; Adams, Judith C.; Fullerton, Barbara; Tarbell, Nancy

    2005-11-15

    Background: Over 85% of pediatric orbital rhabdomyosarcoma (RMS) are cured with combined chemotherapy and radiation. However, the late effects of photon radiation compromise function and cosmetic outcome. Proton radiation can provide excellent tumor dose distributions while sparing normal tissues better than photon irradiation. Methods and Materials: Conformal 3D photon and proton radiotherapy plans were generated for children treated with proton irradiation for orbital RMS at Massachusetts General Hospital. Dose-volume histograms (90%, 50%, 10%) were generated and compared for important orbital and central nervous system structures. Average percentages of total dose prescribed were calculated based on the 3 dose-volume histogram levels for normal orbital structures for both the proton and photon plans. The percent of normal tissue spared by using protons was calculated. Results: Seven children were treated for orbital rhabdomyosarcoma with proton irradiation and standard chemotherapy. The median follow-up is 6.3 years (range, 3.5-9.7 years). Local and distant controls compare favorably to those in other published accounts. There was an advantage in limiting the dose to the brain, pituitary, hypothalamus, temporal lobes, and ipsilateral and contralateral orbital structures. Tumor size and location affect the degree of sparing of normal structures. Conclusions: Fractionated proton radiotherapy is superior to 3D conformal photon radiation in the treatment of orbital RMS. Proton therapy maintains excellent tumor coverage while reducing the radiation dose to adjacent normal structures. Proton radiation therapy minimizes long-term side effects.

  4. Nanoparticle-aided external beam radiotherapy leveraging the Čerenkov effect

    PubMed Central

    Ouyang, Zi; Liu, Bo; Yasmin-Karim, Sayeda; Sajo, Erno; Ngwa, Wilfred

    2016-01-01

    This study investigates the feasibility of exploiting the Čerenkov radiation (CR) present during external beam radiotherapy (EBRT) for significant therapeutic gain, using titanium dioxide (titania) nanoparticles (NPs) delivered via newly designed radiotherapy biomaterials. Using Monte Carlo radiation transport simulations, we calculated the total CR yield inside a tumor volume during EBRT compared to that of the radionuclides. We also considered a novel approach for intratumoral titania delivery using radiotherapy biomaterials (e.g. fiducials) loaded with NPs. The intratumoral distribution/diffusion of titania released from the fiducials was calculated. To confirm the CR induced enhancement in EBRT experimentally, we used 6 MV radiation to irradiate human lung cancer cells with or without titania NPs and performed clonogenic assays. For a radiotherapy biomaterial loaded with 20 μg/g of 2-nm titania NPs, at least 1 μg/g could be delivered throughout a tumor sub-volume of 2-cm diameter after 14 days. This concentration level could inflict substantial damage to cancer cells during EBRT. The Monte Carlo results showed the CR yield by 6 MV radiation was higher than by the radionuclides of interest and hence greater damage may be obtained during EBRT. In vitro study showed significant enhancement with 6 MV radiation and titania NPs. These preliminary findings demonstrate a potential new approach that can be used to take advantage of the CR present during megavoltage EBRT to boost damage to cancer cells. The results provide significant impetus for further experimental studies towards the development of nanoparticle-aided EBRT powered by the Čerenkov effect. PMID:27397906

  5. Estimating Need for Palliative External Beam Radiotherapy in Adult Cancer Patients

    SciTech Connect

    Nieder, Carsten; Pawinski, Adam; Haukland, Ellinor; Dokmo, Raymond; Phillipi, Isabelle; Dalhaug, Astrid

    2010-01-15

    Purpose: Older surveys and benchmark data from different sources have suggested that 46-53% of all radiotherapy courses were administered with palliative intent. In Sweden, 87 annual palliative treatment courses per 100,000 inhabitants were registered in 2001, mainly for the treatment of bone and brain metastases (95% confidence interval [CI] 85-89). The corresponding number for Norway was 95 (95% CI 93-98) in 2004. New data are lacking, although new systemic treatment options might alter this number. Methods and Materials: We collected prospective data on the use of palliative external beam radiotherapy for adult cancer patients during a 12-month period between 2007 and 2008. All patients (median age 69 years) were treated in one Norwegian county and had unlimited, rapid access to treatment. Efforts were made to account for potential overuse. Results: Most irradiated patients had skeletal target volumes, followed by nonbony thoracic targets and brain metastases. In the present population, 133 annual treatments per 100,000 inhabitants were registered (after correction for overuse, but not accounting for radiosurgery of brain metastases and emerging treatment options; e.g., stereotactic radiotherapy for lung and liver metastases; 95% CI 119-149). Because some patients received simultaneous treatment to different target volumes, the annual number of target volumes amounted to 175 per 100,000 inhabitants (95% CI 161-191). Conclusion: The need for palliative radiotherapy has not decreased and might be greater than previously estimated. In regions with a significantly different cancer incidence, age structure, and other socioeconomic factors than northern Europe, separate analyses should be conducted.

  6. Nanoparticle-aided external beam radiotherapy leveraging the Čerenkov effect.

    PubMed

    Ouyang, Zi; Liu, Bo; Yasmin-Karim, Sayeda; Sajo, Erno; Ngwa, Wilfred

    2016-07-01

    This study investigates the feasibility of exploiting the Čerenkov radiation (CR) present during external beam radiotherapy (EBRT) for significant therapeutic gain, using titanium dioxide (titania) nanoparticles (NPs) delivered via newly designed radiotherapy biomaterials. Using Monte Carlo radiation transport simulations, we calculated the total CR yield inside a tumor volume during EBRT compared to that of the radionuclides. We also considered a novel approach for intratumoral titania delivery using radiotherapy biomaterials (e.g. fiducials) loaded with NPs. The intratumoral distribution/diffusion of titania released from the fiducials was calculated. To confirm the CR induced enhancement in EBRT experimentally, we used 6MV radiation to irradiate human lung cancer cells with or without titania NPs and performed clonogenic assays. For a radiotherapy biomaterial loaded with 20μg/g of 2-nm titania NPs, at least 1μg/g could be delivered throughout a tumor sub-volume of 2-cm diameter after 14days. This concentration level could inflict substantial damage to cancer cells during EBRT. The Monte Carlo results showed the CR yield by 6MV radiation was higher than by the radionuclides of interest and hence greater damage might be obtained during EBRT. In vitro study showed significant enhancement with 6MV radiation and titania NPs. These preliminary findings demonstrate a potential new approach that can be used to take advantage of the CR present during megavoltage EBRT to boost damage to cancer cells. The results provide significant impetus for further experimental studies towards the development of nanoparticle-aided EBRT powered by the Čerenkov effect. PMID:27397906

  7. External respiratory motion for abdominal radiotherapy patients: implications for patient alignment

    SciTech Connect

    Kearvell, Rachel; Ebert, Martin A

    2003-12-31

    Conformal external beam radiotherapy relies on accurate spatial positioning of the tumor and normal tissues during treatment. For abdominal patients, this is complicated by the motion of internal organs and the external patient contour due to respiration. As external motion influences the degree of accuracy achievable in patient setup, this motion was studied to provide indication of motions occurring during treatment, as well as to assess the technique of breath-holding at exhale (B-HEX). The motion of external abdominal points (anterior and right lateral) of a series of volunteers was tracked in real-time using an infrared tracking system, with the volunteers in treatment position. The resulting motion data was assessed to evaluate (1) the change in position of each point per breath/breath-hold, (2) the change in position between breaths/breath-holds, and (3) the change in position across the whole recording time. Analysis shows that, for the anterior abdominal point, there is little difference in the variation of position with time for free-breathing as opposed to the B-HEX technique. For the lateral point however, the B-HEX technique reduces the motion during each treatment cycle (i.e., during the breath-hold) and over an extended period (i.e., during a series of breath-holds). The B-HEX technique thus provides greater accuracy for setup to lateral markers and provides the opportunity to reduce systematic and random localization errors.

  8. Experimental and Monte Carlo measurements of dose perturbation around a non-radioactive brachytherapy seed in external beam radiotherapy

    NASA Astrophysics Data System (ADS)

    Steinman, James P.

    limited to ~2 mm upstream and ~5 mm downstream with reference to the seed surface in relation to the incident photon beam. As with other heterogeneities in a human body, the dose perturbation due to I-125 seeds in external beam radiotherapy depends on incident beam energy, field size, and the composition of the seed. However, unlike other heterogeneities, no depth dependence of the seed in the material was noted. With multiple seeds spaced apart and multiple fields normally used in prostate treatment, the dose perturbation due to them may not be clinically significant.

  9. Radiotherapy.

    PubMed

    Adamietz, Irenaus A

    2010-01-01

    The intrathoracic growth of the tumor causes several severe symptoms as cough, dyspnea, chest pain, hemoptysis, hoarseness, anorexia/nausea, and dysphagia. In patients with manifest or threatening symptoms radiotherapy (RT) as an effective measure should be implemented into the management concept. Palliative RT radiotherapy prefers short hypofractionated schemas (e.g. 10 x 3 Gy, 4 x 5 Gy, 2 x 8 Gy, 1 x 10 Gy). Careful radiation planning supports the precision of palliative RT and reduces significantly the complication rate. A good response and prolonged palliation effects (6-12 months) can be achieved in many cases. However, the minimum biologically equivalent dose should not be less than 35 Gy. RT produces a good outcome in all types of metastases of lung carcinoma. In emergencies like VCSS or spinal cord compression RT should be initiated immediately. The selection of the optimal therapy for locally advanced lung carcinoma with malignant airway obstruction is difficult. Both brachytherapy and percutaneous irradiation are effective, however published results including local a sum of response, functionality and life quality demonstrates more benefit by percutaneous RT. Due to different physical properties of these two methods the combination of brachytherapy and external beam irradiation may be advantageous. PMID:19955803

  10. Fast Monte Carlo Electron-Photon Transport Method and Application in Accurate Radiotherapy

    NASA Astrophysics Data System (ADS)

    Hao, Lijuan; Sun, Guangyao; Zheng, Huaqing; Song, Jing; Chen, Zhenping; Li, Gui

    2014-06-01

    Monte Carlo (MC) method is the most accurate computational method for dose calculation, but its wide application on clinical accurate radiotherapy is hindered due to its poor speed of converging and long computation time. In the MC dose calculation research, the main task is to speed up computation while high precision is maintained. The purpose of this paper is to enhance the calculation speed of MC method for electron-photon transport with high precision and ultimately to reduce the accurate radiotherapy dose calculation time based on normal computer to the level of several hours, which meets the requirement of clinical dose verification. Based on the existing Super Monte Carlo Simulation Program (SuperMC), developed by FDS Team, a fast MC method for electron-photon coupled transport was presented with focus on two aspects: firstly, through simplifying and optimizing the physical model of the electron-photon transport, the calculation speed was increased with slightly reduction of calculation accuracy; secondly, using a variety of MC calculation acceleration methods, for example, taking use of obtained information in previous calculations to avoid repeat simulation of particles with identical history; applying proper variance reduction techniques to accelerate MC method convergence rate, etc. The fast MC method was tested by a lot of simple physical models and clinical cases included nasopharyngeal carcinoma, peripheral lung tumor, cervical carcinoma, etc. The result shows that the fast MC method for electron-photon transport was fast enough to meet the requirement of clinical accurate radiotherapy dose verification. Later, the method will be applied to the Accurate/Advanced Radiation Therapy System ARTS as a MC dose verification module.

  11. Multiobjective optimization with a modified simulated annealing algorithm for external beam radiotherapy treatment planning

    SciTech Connect

    Aubry, Jean-Francois; Beaulieu, Frederic; Sevigny, Caroline; Beaulieu, Luc; Tremblay, Daniel

    2006-12-15

    Inverse planning in external beam radiotherapy often requires a scalar objective function that incorporates importance factors to mimic the planner's preferences between conflicting objectives. Defining those importance factors is not straightforward, and frequently leads to an iterative process in which the importance factors become variables of the optimization problem. In order to avoid this drawback of inverse planning, optimization using algorithms more suited to multiobjective optimization, such as evolutionary algorithms, has been suggested. However, much inverse planning software, including one based on simulated annealing developed at our institution, does not include multiobjective-oriented algorithms. This work investigates the performance of a modified simulated annealing algorithm used to drive aperture-based intensity-modulated radiotherapy inverse planning software in a multiobjective optimization framework. For a few test cases involving gastric cancer patients, the use of this new algorithm leads to an increase in optimization speed of a little more than a factor of 2 over a conventional simulated annealing algorithm, while giving a close approximation of the solutions produced by a standard simulated annealing. A simple graphical user interface designed to facilitate the decision-making process that follows an optimization is also presented.

  12. Long-term changes in natural killer activity after external pelvic radiotherapy. [X ray

    SciTech Connect

    Onsrud, M.; Thorsby, E.

    1981-05-01

    Peripheral lymphocytes from 24 Stage I endometrial cancer patients treated 3 to 5 years earlier were tested for their natural killer (NK) cell activity against K562 cell line targets and for surface markers. The patients were free of recurrence at the time of investigation. They belonged to a clinical trial where group A (control) received surgery only and group B also received 4000 rad external pelvic field irradiation post surgery. Lymphocyte suspensions from group B patients showed, on a per cell basis, a higher NK activity and a higher percentage of cells bearing receptors for the Fc part of immunoglobulin G than did group A lymphocytes. Expressed per volume unit of blood, however, these differences were insignificant. A depletion of T lymphocytes from the peripheral circulation was seen 3 to 5 years after radiotherapy. On a per cell basis, however, the T cell functional capacity, as estimated from the mitogenic (PHA) response, seemed unaffected.

  13. Age-dependent protection quantities for external photon irradiation.

    PubMed

    Chou, D P; Wang, J N; Chen, I J

    2001-01-01

    The age-dependent conversion coefficients of the protection quantities, the equivalent dose and the effective dose defined by the International Commission on Radiological Protection (ICRP), are obtained. A Monte Carlo computer code and the age-dependent hermaphrodite mathematical phantoms of six age groups: newborn, 1, 5, 10, 15 years old and adult are used for the evaluation. Twenty-three photon source energies from 10 keV to 10 MeV and six kinds of irradiation geometries: AP, PA, RLAT, LLAT, ROT, and ISO are chosen in the calculation. The evaluated conversion coefficients for the adult are compared with those in ICRP Publication 74 with good agreement. The conversion coefficients of the equivalent dose and the effective dose increase while the age of the phantom decreases, but with some exceptions for the AP irradiation geometry under certain conditions. PMID:11605795

  14. Two-temperature accretion disks with electron-positron pairs - Effects of Comptonized external soft photons

    NASA Technical Reports Server (NTRS)

    Kusunose, Masaaki; Takahara, Fumio

    1990-01-01

    The present account of the effects of soft photons from external sources on two-temperature accretion disks in electron-positron pair equilibrium solves the energy-balance equation for a given radial distribution of the input rate of soft photons, taking into account their bremsstrahlung and Comptonization. Critical rate behavior is investigated as a function of the ratio of the energy flux of incident soft photons and the energy-generation rate. As in a previous study, the existence of a critical accretion rate is established.

  15. Gold nanoparticle induced vasculature damage in radiotherapy: Comparing protons, megavoltage photons, and kilovoltage photons

    SciTech Connect

    Lin, Yuting Paganetti, Harald; Schuemann, Jan; McMahon, Stephen J.

    2015-10-15

    Purpose: The purpose of this work is to investigate the radiosensitizing effect of gold nanoparticle (GNP) induced vasculature damage for proton, megavoltage (MV) photon, and kilovoltage (kV) photon irradiation. Methods: Monte Carlo simulations were carried out using tool for particle simulation (TOPAS) to obtain the spatial dose distribution in close proximity up to 20 μm from the GNPs. The spatial dose distribution from GNPs was used as an input to calculate the dose deposited to the blood vessels. GNP induced vasculature damage was evaluated for three particle sources (a clinical spread out Bragg peak proton beam, a 6 MV photon beam, and two kV photon beams). For each particle source, various depths in tissue, GNP sizes (2, 10, and 20 nm diameter), and vessel diameters (8, 14, and 20 μm) were investigated. Two GNP distributions in lumen were considered, either homogeneously distributed in the vessel or attached to the inner wall of the vessel. Doses of 30 Gy and 2 Gy were considered, representing typical in vivo enhancement studies and conventional clinical fractionation, respectively. Results: These simulations showed that for 20 Au-mg/g GNP blood concentration homogeneously distributed in the vessel, the additional dose at the inner vascular wall encircling the lumen was 43% of the prescribed dose at the depth of treatment for the 250 kVp photon source, 1% for the 6 MV photon source, and 0.1% for the proton beam. For kV photons, GNPs caused 15% more dose in the vascular wall for 150 kVp source than for 250 kVp. For 6 MV photons, GNPs caused 0.2% more dose in the vascular wall at 20 cm depth in water as compared to at depth of maximum dose (Dmax). For proton therapy, GNPs caused the same dose in the vascular wall for all depths across the spread out Bragg peak with 12.7 cm range and 7 cm modulation. For the same weight of GNPs in the vessel, 2 nm diameter GNPs caused three times more damage to the vessel than 20 nm diameter GNPs. When the GNPs were attached

  16. Gold nanoparticle induced vasculature damage in radiotherapy: Comparing protons, megavoltage photons, and kilovoltage photons

    PubMed Central

    Lin, Yuting; Paganetti, Harald; McMahon, Stephen J.; Schuemann, Jan

    2015-01-01

    Purpose: The purpose of this work is to investigate the radiosensitizing effect of gold nanoparticle (GNP) induced vasculature damage for proton, megavoltage (MV) photon, and kilovoltage (kV) photon irradiation. Methods: Monte Carlo simulations were carried out using tool for particle simulation (TOPAS) to obtain the spatial dose distribution in close proximity up to 20 μm from the GNPs. The spatial dose distribution from GNPs was used as an input to calculate the dose deposited to the blood vessels. GNP induced vasculature damage was evaluated for three particle sources (a clinical spread out Bragg peak proton beam, a 6 MV photon beam, and two kV photon beams). For each particle source, various depths in tissue, GNP sizes (2, 10, and 20 nm diameter), and vessel diameters (8, 14, and 20 μm) were investigated. Two GNP distributions in lumen were considered, either homogeneously distributed in the vessel or attached to the inner wall of the vessel. Doses of 30 Gy and 2 Gy were considered, representing typical in vivo enhancement studies and conventional clinical fractionation, respectively. Results: These simulations showed that for 20 Au-mg/g GNP blood concentration homogeneously distributed in the vessel, the additional dose at the inner vascular wall encircling the lumen was 43% of the prescribed dose at the depth of treatment for the 250 kVp photon source, 1% for the 6 MV photon source, and 0.1% for the proton beam. For kV photons, GNPs caused 15% more dose in the vascular wall for 150 kVp source than for 250 kVp. For 6 MV photons, GNPs caused 0.2% more dose in the vascular wall at 20 cm depth in water as compared to at depth of maximum dose (Dmax). For proton therapy, GNPs caused the same dose in the vascular wall for all depths across the spread out Bragg peak with 12.7 cm range and 7 cm modulation. For the same weight of GNPs in the vessel, 2 nm diameter GNPs caused three times more damage to the vessel than 20 nm diameter GNPs. When the GNPs were attached

  17. Combined Proton and Photon Conformal Radiotherapy for Intracranial Atypical and Malignant Meningioma

    SciTech Connect

    Boskos, Christos Feuvret, Loic; Noel, Georges; Habrand, Jean-Louis; Pommier, Pascal; Alapetite, Claire; Mammar, Hamid; Ferrand, Regis; Boisserie, Gilbert; Mazeron, Jean-Jacques

    2009-10-01

    Purpose: To evaluate retrospectively the efficacy of conformal fractionated radiotherapy combining proton and photon beams after primary surgery for treatment of atypical and malignant meningiomas. Patients and Methods: Between September 1999 and October 2006, 24 patients (12 male, 12 female) with histopathologically proven meningioma (atypical 19, malignant 5) received postoperative combined radiotherapy with a 201-MeV proton beam at the Centre Protontherapie d'Orsay and a high-energy photon beam. Six patients underwent gross total resection and 18 a subtotal resection. Median gross tumor volume and clinical target volume were 44.7 cm{sup 3} and 153.3 cm{sup 3}, respectively. Mean total irradiation dose was 65.01 CGE (cobalt gray equivalent), with a mean proton total dose of 34.05 CGE and a mean photon total dose 30.96 CGE. Results: The median (range) follow-up interval was 32.2 (1-72) months. The overall mean local relapse-free interval was 27.2 (10-50) months, 28.3 (10-50) months for atypical meningioma and 23 (13-33) months for malignant meningioma. Ten tumors recurred locally. One-, 2-, 3-, 4-, 5-, and 8- year local control rates for the entire group of patients were 82.9% {+-} 7.8%, 82.9% {+-} 7.8%, 61.3% {+-} 11%, 61.3% {+-} 11%, 46.7% {+-} 12.3%, and 46.7% {+-} 12.3%, respectively. One-, 2-, 3-, 4-, 5-, and 8- year overall survival rates were 100%, 95.5% {+-} 4.4%, 80.4% {+-} 8.8%, 65.3% {+-} 10.6%, 53.2% {+-} 11.6%, and 42.6% {+-} 13%, respectively. Survival was significantly associated with total dose. There was no acute morbidity of radiotherapy. One patient developed radiation necrosis 16 months after treatment. Conclusions: Postoperative combination of conformal radiotherapy with protons and photons for atypical and malignant meningiomas is a well-tolerated treatment producing long-term tumor stabilization.

  18. Investigation of photon beam models in heterogeneous media of modern radiotherapy.

    PubMed

    Ding, W; Johnston, P N; Wong, T P Y; Bubb, I F

    2004-06-01

    This study investigates the performance of photon beam models in dose calculations involving heterogeneous media in modern radiotherapy. Three dose calculation algorithms implemented in the CMS FOCUS treatment planning system have been assessed and validated using ionization chambers, thermoluminescent dosimeters (TLDs) and film. The algorithms include the multigrid superposition (MGS) algorithm, fast Fourier Transform Convolution (FFTC) algorithm and Clarkson algorithm. Heterogeneous phantoms used in the study consist of air cavities, lung analogue and an anthropomorphic phantom. Depth dose distributions along the central beam axis for 6 MV and 10 MV photon beams with field sizes of 5 cm x 5 cm and 10 cm x 10 cm were measured in the air cavity phantoms and lung analogue phantom. Point dose measurements were performed in the anthropomorphic phantom. Calculated results with three dose calculation algorithms were compared with measured results. In the air cavity phantoms, the maximum dose differences between the algorithms and the measurements were found at the distal surface of the air cavity with a 10 MV photon beam and a 5 cm x 5 cm field size. The differences were 3.8%. 24.9% and 27.7% for the MGS. FFTC and Clarkson algorithms. respectively. Experimental measurements of secondary electron build-up range beyond the air cavity showed an increase with decreasing field size, increasing energy and increasing air cavity thickness. The maximum dose differences in the lung analogue with 5 cm x 5 cm field size were found to be 0.3%. 4.9% and 6.9% for the MGS. FFTC and Clarkson algorithms with a 6 MV photon beam and 0.4%. 6.3% and 9.1% with a 10 MV photon beam, respectively. In the anthropomorphic phantom, the dose differences between calculations using the MGS algorithm and measurements with TLD rods were less than +/-4.5% for 6 MV and 10 MV photon beams with 10 cm x 10 cm field size and 6 MV photon beam with 5 cm x 5 cm field size, and within +/-7.5% for 10 MV with 5 cm

  19. On charged particle equilibrium violation in external photon fields

    SciTech Connect

    Bouchard, Hugo; Seuntjens, Jan; Palmans, Hugo

    2012-03-15

    Purpose: In a recent paper by Bouchard et al.[Med. Phys. 36(10), 4654-4663 (2009)], a theoretical model of quality correction factors for idealistic so-called plan-class specific reference (PCSR) fields was proposed. The reasoning was founded on the definition of PCSR fields made earlier by Alfonso et al.[Med. Phys. 35(11), 5179-5186 (2008)], requiring the beam to achieve charged particle equilibrium (CPE), in a time-averaged sense, in the reference medium. The relation obtained by Bouchard et al. was derived using Fano's theorem (1954) which states that if CPE is established in a given medium, the dose is independent of point-to-point density variations. A potential misconception on the achievability of the condition required by Fano (1954) might be responsible for false practical conclusions, both in the definition of PCSR fields as well as the theoretical model of quality correction factor. Methods: In this paper, the practical achievability of CPE in external beams is treated in detail. The fact that this condition is not achievable in single or composite deliveries is illustrated by an intuitive method and is also formally demonstrated. Conclusions: Fano's theorem is not applicable in external beam radiation dosimetry without (virtually) removing attenuation effects, and therefore, the relation conditionally defined by Bouchard et al. (2009) cannot be valid in practice. A definition of PCSR fields in the recent formalism for nonstandard beams proposed by Alfonso et al. (2008) should be modified, revising the criterion of CPE condition. The authors propose reconsidering the terminology used to describe standard and nonstandard beams. The authors argue that quality correction factors of intensity modulated radiation therapy PCSR fields (i.e., k{sub Q{sub p{sub c{sub s{sub r,Q}{sup f{sub p}{sub c}{sub s}{sub r},f{sub r}{sub e}{sub f}}}}}}) could be unity under ideal conditions, but it is concluded that further investigation is necessary to confirm that hypothesis.

  20. Secondary external-beam radiotherapy and hyperthermia for local recurrence after 125-iodine implantation in adenocarcinoma of the prostate

    SciTech Connect

    Kaplan, I.; Kapp, D.S.; Bagshaw, M.A. )

    1991-03-01

    At Standford, six patients underwent a course of external radiotherapy after local recurrence following 125-iodine implantation. Four of the six patients also received concomitant hyperthermia. Four patients were initially managed with hormonal manipulation at time of local relapse and subsequently received external beam radiotherapy with or without hyperthermia. The hyperthermia was non-invasively induced using an annular phased array radiative electromagnetic system. Treatment was well tolerated, and none of the patients experienced severe rectal or bladder complications. Three patients are free from disease; one patient experience local-regional recurrence based on biopsy; one recurred in the bladder, was treated with cystoprostatectomy and subsequently succumbed to metastatic disease; and one patient died of presumed metastatic disease. External-beam irradiation with concurrent hyperthermia can be safely delivered to treat locally recurrent prostatic carcinoma after 125-iodine implantation.

  1. SU-E-T-221: Investigation of Lower Energy (< 6 MV) Photon Beams for Cancer Radiotherapy

    SciTech Connect

    Zhang, Y; Ming, X; Feng, Y; Zhou, L; Ahmad, M; Deng, J; Nguyen, K; Griffin, M

    2014-06-01

    Purpose: To study the potential applications of the lower energy (< 6MV) photon beams in the radiotherapeutic management of pediatric cancer and lung cancer patients. Methods: Photon beams of 2, 3, 4, 5 and 6MV were first simulated with EGS4/BEAM and then used for Monte-Carlo dose calculations. For four pediatric patients with abdominal and brain lesions, six 3D-conformal radiotherapy (3DCRT) plans were generated using single photon energy (2 to 6MV) or mixed energies (3 and 6MV). Furthermore, a virtual machine of 3 and 6MV was commissioned in a treatment planning system (TPS) based on Monte-Carlo simulated data. Three IMRT plans of a lung cancer patient were generated on this virtual machine. All plans were normalized to D95% of target dose for 6MV plan and then compared in terms of integral dose and OAR sparing. Results: For the four pediatric patients, the integral dose for the 2, 3, 4 and 5MV plans increased by 9%, 5%, 3.5%, 1.7%, respectively as compared to 6MV. Almost all OARs in the 2MV plan received more than 10% more doses than 6MV. Mixed energy 3DCRT plans were of the same quality as 6MV plans. For the lung IMRT plans, both the 3MV plan and the mixed beam plan showed better OAR sparing in comparison to 6MV plan. Specifically, the maximum and mean doses to the spinal cord in the mixed energy plan were lower by 21% and 16%, respectively. Conclusion: Single lower energy photon beam was found to be inferior to 6MV in the radiotherapy of pediatric patients and lung cancer patients when the integral doses and the doses to the OARs were considered. However, mixed energy plans combining low with high energy beams showed significant OAR sparing while maintaining the same PTV coverage. Investigation with more patient data is ongoing for further confirmation.

  2. Six fractions per week of external beam radiotherapy and high-dose-rate brachytherapy for carcinoma of the uterine cervix: A phase I/II study

    SciTech Connect

    Yoon, Sang Min; Huh, Seung Jae . E-mail: sjhuh@smc.samsung.co.kr; Park, Won; Lee, Jeung Eun; Park, Young Je; Nam, Hee Rim; Lim, Do Hoon; Ahn, Yong Chan

    2006-08-01

    Purpose: This study evaluated the treatment results of external beam radiotherapy administered in six fractions per week and high-dose-rate (HDR) brachytherapy for the treatment of cervical cancer. Methods and Materials: From July 2000 to July 2003, 43 patients were enrolled in this study. The patients received 45 Gy from a 10-MV photon beam using four-field box or anterior-posterior beams. Parametrial regions and the pelvic side walls were boosted with up to 50.4 Gy using a midline block. The daily fraction dose was 1.8 Gy administered in six-weekly fractions, from Monday to Saturday. HDR brachytherapy was also delivered at doses of 24 Gy to point A in six fractions twice a week. The median follow-up time was 37 months (range, 9-60 months). Results: The median overall treatment time was 51 days for all patients (range, 44-62 days). Thirty-four patients (79.1%) achieved complete remission and 8 (18.6%) achieved partial remission after radiotherapy. Locoregional recurrence occurred in 5 patients (11.6%), and a distant metastasis was encountered in 6 patients (13.9%). The 3-year overall survival, locoregional, and distant metastasis-free survival rates were 74.7%, 87.8%, and 84.7%, respectively. Grade 2 and 3 late rectal complications were encountered in 3 (6.5%) and 1 (2.2%), respectively. There were no Grade 3 late bladder complications. Conclusions: Six fractions per week of external beam radiotherapy and HDR brachytherapy is an effective treatment for patients with a carcinoma of the uterine cervix and can be used as a possible alternative to concomitant chemoradiotherapy in elderly patients or in patients with co-morbidity.

  3. Collective Evidence for Inverse Compton Emission from External Photons in High-Power Blazars

    NASA Technical Reports Server (NTRS)

    Meyer, Eileen T.; Fossati, Giovanni; Georganopoulos, Markos; Lister, Matthew L.

    2012-01-01

    We present the first collective evidence that Fermi-detected jets of high kinetic power (L(sub kin)) are dominated by inverse Compton emission from upscattered external photons. Using a sample with a broad range in orientation angle, including radio galaxies and blazars, we find that very high power sources (L(sub kin) > 10(exp 45.5) erg/s) show a significant increase in the ratio of inverse Compton to synchrotron power (Compton dominance) with decreasing orientation angle, as measured by the radio core dominance and confirmed by the distribution of superluminal speeds. This increase is consistent with beaming expectations for external Compton (EC) emission, but not for synchrotron self Compton (SSC) emission. For the lowest power jets (L(sub kin) < 10(exp 43.5) erg /s), no trend between Compton and radio core dominance is found, consistent with SSC. Importantly, the EC trend is not seen for moderately high power flat spectrum radio quasars with strong external photon fields. Coupled with the evidence that jet power is linked to the jet speed, this finding suggests that external photon fields become the dominant source of seed photons in the jet comoving frame only for the faster and therefore more powerful jets.

  4. Quantification of shape variation of prostate and seminal vesicles during external beam radiotherapy

    SciTech Connect

    Deurloo, Kirsten; Rasch, Coen . E-mail: portal@nki.nl

    2005-01-01

    Purpose: The prostate is known to translate and rotate under influence of rectal filling changes and many studies have addressed the magnitude of these motions. However, prostate shape variations also have been reported. For image-guided radiotherapy, it is essential to know the relative magnitude of translations, rotations, and shape variation so that the most appropriate correction strategy can be chosen. However, no quantitative analysis of shape variation has been performed. It is, therefore, the purpose of this article to develop a method to determine shape variation of complex organs and apply it to determine shape variation during external beam radiotherapy of a GTV (gross tumor volume) consisting of prostate and seminal vesicles. Methods and materials: For this study, the data of 19 patients with prostate cancer were used. Each patient received a planning computed tomography (CT) scan and 8-12 (11 on average) repeat CT scans that were made during the course of conformal radiotherapy. One observer delineated the GTV in all scans, and volume variations were measured. After matching the GTVs for each patient for translation and rotation, a coverage probability matrix was constructed and the 50% isosurface was taken to determine the average GTV surface. Perpendicular distances between the average GTV and the individual GTVs were calculated for each point of the average GTV, and their variation was expressed in terms of local standard deviation (SD). The local SDs of the shape variation of all 19 patients were mapped onto a reference case by matching and morphing of the individual average GTVs. Repeated delineation of the GTV was done for 6 patients to determine intraobserver variation. Finally, the measured shape variation was corrected for intraobserver variation to estimate the 'real' shape variation. Results: No significant variations in GTV volume were observed. The measured shape variation (including delineation variation) was largest at the tip of the

  5. Safety and Efficacy of Thoracic External Beam Radiotherapy After Airway Stenting in Malignant Airway Obstruction

    SciTech Connect

    Rochet, Nathalie; Hauswald, Henrik; Schmaus, Martina; Hensley, Frank; Huber, Peter; Eberhardt, Ralf; Herth, Felix J.; Debus, Juergen; Neuhof, Dirk

    2012-05-01

    Purpose: We retrospectively evaluated the outcome and toxicity of external beam radiotherapy (EBRT) after airway stents were placed in patients treated for malignant airway obstruction. Methods and Materials: Between 2004 and 2009, we performed airway stenting followed by EBRT in 43 patients for symptomatic primary lung cancer (n = 31) or other thoracic malignancies (n = 12). The median time interval between stent placement and first irradiation was 14 days. A median total dose of 50 Gy was delivered. Sixty-seven percent of the patients had reduced performance status (Karnofsky performance score, {<=}70). Results: EBRT had to be stopped prematurely in 16 patients (37%), at a median total dose of 17 Gy, for various reasons. In this group of patients, the survival was poor, with a median overall survival (OS) of only 21 days. Twenty-seven patients (63%) completed radiotherapy as planned, with a median OS of 8.4 months. Fourteen of 43 patients (33%) developed at least one Common Terminology Criteria for Adverse Event of grade 3 to 5. The most common event was a malignant restenosis of the stent leading to asphyxia (n = 7), followed by fistula formation (n = 4), necrosis (n = 3), mediastinitis with abscess (n = 1), secondary nonmalignant airway stenosis (n = 1), and hemoptysis (n = 1). With the exception of one event, all events were associated with a local progression of the tumor. Conclusions: Although the long-term prognosis for patients with malignant airway obstruction is poor, airway stenting combined with EBRT offers a possible therapeutic option, achieving fast relief of acute respiratory distress with an associated antitumor effect, resulting in a potential survival benefit. However, due to local advanced tumor growth, increased rates of adverse events are to be expected, necessitating careful monitoring.

  6. Targeted Intraoperative Radiotherapy for Breast Cancer in Patients in Whom External Beam Radiation Is Not Possible

    SciTech Connect

    Keshtgar, Mohammed R.S.; Joseph, David; Stacey, Chris; Metaxas, Marinos G.; Corica, Tammy; Williams, Norman R.; Baum, Michael

    2011-05-01

    Purpose: External beam radiation therapy (EBRT) following wide local excision of the primary tumor is the standard treatment in early breast cancer. In some circumstances this procedure is not possible or is contraindicated or difficult. The purpose of this study was to determine the safety and efficacy of targeted intraoperative radiotherapy (TARGIT) when EBRT is not feasible. Methods and Materials: We report our experience with TARGIT in three centers (Australia, Germany, and the United Kingdom) between 1999 and 2008. Patients at these centers received a single radiation dose of 20 Gy to the breast tissue in contact with the applicator (or 6 Gy at 1-cm distance), as they could not be given EBRT and were keen to avoid mastectomy. Results: Eighty patients were treated with TARGIT. Reasons for using TARGIT were 21 patients had previously received EBRT, and 31 patients had clinical reasons such as systemic lupus erythematosus, motor neuron disease, Parkinson's disease, ankylosing spondylitis, morbid obesity, and cardiovascular or severe respiratory disease. Three of these patients received percutaneous radiotherapy without surgery; 28 patients were included for compelling personal reasons, usually on compassionate grounds. After a median follow-up of 38 months, only two local recurrences were observed, an annual local recurrence rate of 0.75% (95% confidence interval, 0.09%-2.70%). Conclusions: While we await the results of the randomized trial (over 2,000 patients have already been recruited), TARGIT is an acceptable option but only in highly selected cases that cannot be recruited in the trial and in whom EBRT is not feasible/possible.

  7. Patient preferences regarding intraoperative versus external beam radiotherapy following breast-conserving surgery.

    PubMed

    Alvarado, Michael D; Conolly, Jay; Park, Catherine; Sakata, Theadora; Mohan, Aron J; Harrison, Brittany L; Hayes, Mitchell; Esserman, Laura J; Ozanne, Elissa M

    2014-01-01

    The TARGIT-A Trial is an international randomized, prospective trial comparing intraoperative radiotherapy (IORT) for equivalence to external beam radiotherapy (EBRT) following lumpectomy for invasive breast cancer in selected low-risk patients; early results suggest that outcomes are similar. In addition to effectiveness data and cost considerations, the preferences of patients should help inform practice. This study was undertaken to explore and quantify preference in choosing between IORT and the current standard, EBRT. Eligible subjects were current or past candidates for breast-conserving surgery and radiation being seen at the University of California, San Francisco Breast Care Center. A trade-off technique varying the risk of local recurrence for IORT was used to quantify any additional accepted risk that these patients would accept to receive either treatment. Patients were first presented with a slideshow comparing EBRT with the experimental IORT option before being asked their preferences given hypothetical 10-year local recurrence risks. Patients were then given a questionnaire on demographic, social and clinical factors. Data from 81 patients were analyzed. The median additional accepted risk to have IORT was 2.3 % (-9 to 39 %), mean 3.2 %. Only 7 patients chose to accept additional risk for EBRT; 22 accepted IORT at no additional risk; and the remaining 52 chose IORT with some additional risk. Patients weigh trade-offs of risks and benefits when presented with medical treatment choices. Our results show that the majority of breast cancer patients will accept a small increment of local risk for a simpler delivery of radiation. Further studies that incorporate outcome and side effect data from the TARGIT-A trial clarify the expected consequences of a local recurrence, and include an expanded range of radiation options that could help guide clinical decision making in this area. PMID:24292868

  8. Postoperative External Beam Radiotherapy for Differentiated Thyroid Cancer: Outcomes and Morbidity With Conformal Treatment

    SciTech Connect

    Schwartz, David L. Lobo, Mark J.; Ang, K. Kian; Morrison, William H.; Rosenthal, David I.; Ahamad, Anesa; Evans, Douglas B.; Clayman, Gary; Sherman, Steven I.; Garden, Adam S.

    2009-07-15

    Purpose: To review institutional outcomes for patients treated for differentiated thyroid cancer with postoperative conformal external beam radiotherapy (EBRT). Methods and Materials: This is a single-institution retrospective review of 131 consecutive patients with differentiated thyroid cancer who underwent EBRT between January 1996 and December 2005. Histologic diagnoses included 104 papillary, 21 follicular, and six mixed papillary-follicular types. American Joint Committee on Cancer stage distribution was Stage III in 2 patients, Stage IVa-IVc in 128, and not assessable in 1. Thirty-four patients (26%) had high-risk histologic types and 76 (58%) had recurrent disease. Extraglandular disease spread was seen in 126 patients (96%), microscopically positive surgical margins were seen in 62 patients (47%), and gross residual disease was seen in 15 patients (11%). Median EBRT dose was 60 Gy (range, 38-72 Gy). Fifty-seven patients (44%) were treated with intensity-modulated radiotherapy (IMRT) to a median dose of 60 Gy (range, 56-66 Gy). Median follow-up was 38 months (range, 0-134 months). Results: Kaplan-Meier estimates of locoregional relapse-free survival, disease-specific survival, and overall survival at 4 years were 79%, 76%, and 73%, respectively. On multivariate analysis, high-risk histologic features and gross residual disease predicted for inferior locoregional relapse-free survival, whereas high-risk histologic features, M1 disease, and gross residual disease predicted for inferior disease-specific and overall survival. The IMRT did not impact on survival outcomes, but was associated with less frequent severe late morbidity (12% vs. 2%). Conclusions: Postoperative conformal EBRT provides durable locoregional disease control for patients with high-risk differentiated thyroid cancer if disease is reduced to microscopic burden. Patients with gross disease face significantly worse outcomes. The IMRT may significantly reduce chronic radiation morbidity, but

  9. Risk of second malignant neoplasm following proton versus intensity-modulated photon radiotherapies for hepatocellular carcinoma

    NASA Astrophysics Data System (ADS)

    Taddei, Phillip J.; Howell, Rebecca M.; Krishnan, Sunil; Scarboro, Sarah B.; Mirkovic, Dragan; Newhauser, Wayne D.

    2010-12-01

    Hepatocellular carcinoma (HCC), the sixth most common cancer in the world, is a global health concern. Radiotherapy for HCC is uncommon, largely because of the likelihood of radiation-induced liver disease, an acute side effect that is often fatal. Proton beam therapy (PBT) and intensity-modulated radiation therapy (IMRT) may offer HCC patients a better option for treating the diseased liver tissue while largely sparing the surrounding tissues, especially the non-tumor liver. However, even advanced radiotherapies carry a risk of late effects, including second malignant neoplasms (SMNs). It is unclear whether PBT or IMRT confers less risk of an SMN than the other. The purpose of this study was to compare the predicted risk of developing an SMN for a patient with HCC between PBT and IMRT. For both treatments, radiation doses in organs and tissues from primary radiation were determined using a treatment planning system; doses in organs and tissues from stray radiation from PBT were determined using Monte Carlo simulations and from IMRT using thermo-luminescent dosimeter measurements. Risk models of SMN incidence were taken from the literature. The predicted absolute lifetime attributable risks of SMN incidence were 11.4% after PBT and 19.2% after IMRT. The results of this study suggest that using proton beams instead of photon beams for radiotherapy may reduce the risk of SMN incidence for some HCC patients.

  10. Investigations of high mobility single crystal chemical vapor deposition diamond for radiotherapy photon beam monitoring

    SciTech Connect

    Tromson, D.; Descamps, C.; Tranchant, N.; Bergonzo, P.; Nesladek, M.; Isambert, A.

    2008-03-01

    The intrinsic properties of diamond make this material theoretically very suitable for applications in medical physics. Until now ionization chambers have been fabricated from natural stones and are commercialized by PTW, but their fairly high costs and long delivery times have often limited their use in hospital. The properties of commercialized intrinsic polycrystalline diamond were investigated in the past by many groups. The results were not completely satisfactory due to the nature of the polycrystalline material itself. In contrast, the recent progresses in the growth of high mobility single crystal synthetic diamonds prepared by chemical vapor deposition (CVD) technique offer new alternatives. In the framework of the MAESTRO project (Methods and Advanced Treatments and Simulations for Radio Oncology), the CEA-LIST is studying the potentialities of synthetic diamond for new techniques of irradiation such as intensity modulated radiation therapy. In this paper, we present the growth and characteristics of single crystal diamond prepared at CEA-LIST in the framework of the NoRHDia project (Novel Radiation Hard CVD Diamond Detector for Hadrons Physics), as well as the investigations of high mobility single crystal CVD diamond for radiotherapy photon beam monitoring: dosimetric analysis performed with the single crystal diamond detector in terms of stability and repeatability of the response signal, signal to noise ratio, response speed, linearity of the signal versus the absorbed dose, and dose rate. The measurements performed with photon beams using radiotherapy facilities demonstrate that single crystal CVD diamond is a good alternative for air ionization chambers for beam quality control.

  11. EPR dosimetry of radiotherapy photon beams in inhomogeneous media using alanine films

    NASA Astrophysics Data System (ADS)

    Helge Østerås, Bjørn; Olaug Hole, Eli; Rune Olsen, Dag; Malinen, Eirik

    2006-12-01

    In the current work, EPR (electron paramagnetic resonance) dosimetry using alanine films (134 µm thick) was utilized for dose measurements in inhomogeneous phantoms irradiated with radiotherapy photon beams. The main phantom material was PMMA, while either Styrofoam or aluminium was introduced as an inhomogeneity. The phantoms were irradiated to a maximum dose of about 30 Gy with 6 or 15 MV photons. The performance of the alanine film dosimeters was investigated and compared to results from ion chamber dosimetry, Monte Carlo simulations and radiotherapy treatment planning calculations. It was found that the alanine film dosimeters had a linear dose response above approximately 5 Gy, while a background signal obscured the response at lower dose levels. For doses between 5 and 60 Gy, the standard deviation of single alanine film dose estimates was about 2%. The alanine film dose estimates yielded results comparable to those from the Monte Carlo simulations and the ion chamber measurements, with absolute differences between estimates in the order of 1 15%. The treatment planning calculations exhibited limited applicability. The current work shows that alanine film dosimetry is a method suitable for estimating radiotherapeutical doses and for dose measurements in inhomogeneous media.

  12. External beam radiotherapy as postoperative treatment of diffuse pigmented villonodular synovitis

    SciTech Connect

    Berger, Bernhard . E-mail: Bernhard.Berger@med.uni-tuebingen.de; Ganswindt, Ute; Bamberg, Michael; Hehr, Thomas

    2007-03-15

    Purpose: Diffuse pigmented villonodular synovitis is a rare proliferative disorder of synovial membranes with invasive and expansive growth patterns. Radical synovectomy is regarded as the treatment of choice. However, because of the high recurrence rates, additive treatment might be useful. Radiotherapy (RT) has been evaluated with positive results, but the optimal treatment schedules are vague. We have reviewed our experience with postoperative RT in cases of suspected or proven residual disease. Methods and Materials: Between December 1996 and January 2006, 7 diffuse pigmented villonodular synovitis patients underwent RT at our institution. The most common location was the knee joint (5 patients). All patients underwent radical surgery and were treated subsequently with 6-MV photon RT. The total doses applied were 30-50 Gy, depending on the resection status and estimated risk of relapse. For analysis, we retrospectively reviewed all patients in April 2006. Results: The mean follow-up time was 29 months (range, 3-112 months). RT had no acute adverse effects. At the assessment, no evidence was found of recurrent or persisting disease in any patient. Of the 7 patients, 6 reported asymptomatic limb function and excellent quality of life; 1 patient had persistent restriction of joint movement after repeated surgery. No radiotherapeutic late effects were seen. Conclusion: The results of our series have confirmed the efficacy and safety of postoperative RT for diffuse pigmented villonodular synovitis. Hence, this treatment should be considered for patients with suspected or proven residual disease.

  13. A Review on the Use of Grid-Based Boltzmann Equation Solvers for Dose Calculation in External Photon Beam Treatment Planning

    PubMed Central

    Kan, Monica W. K.; Yu, Peter K. N.; Leung, Lucullus H. T.

    2013-01-01

    Deterministic linear Boltzmann transport equation (D-LBTE) solvers have recently been developed, and one of the latest available software codes, Acuros XB, has been implemented in a commercial treatment planning system for radiotherapy photon beam dose calculation. One of the major limitations of most commercially available model-based algorithms for photon dose calculation is the ability to account for the effect of electron transport. This induces some errors in patient dose calculations, especially near heterogeneous interfaces between low and high density media such as tissue/lung interfaces. D-LBTE solvers have a high potential of producing accurate dose distributions in and near heterogeneous media in the human body. Extensive previous investigations have proved that D-LBTE solvers were able to produce comparable dose calculation accuracy as Monte Carlo methods with a reasonable speed good enough for clinical use. The current paper reviews the dosimetric evaluations of D-LBTE solvers for external beam photon radiotherapy. This content summarizes and discusses dosimetric validations for D-LBTE solvers in both homogeneous and heterogeneous media under different circumstances and also the clinical impact on various diseases due to the conversion of dose calculation from a conventional convolution/superposition algorithm to a recently released D-LBTE solver. PMID:24066294

  14. Performance analysis of the Monte Carlo code MCNP4A for photon-based radiotherapy applications

    SciTech Connect

    DeMarco, J.J.; Solberg, T.D.; Wallace, R.E.; Smathers, J.B.

    1995-12-31

    The Los Alamos code MCNP4A (Monte Carlo M-Particle version 4A) is currently used to simulate a variety of problems ranging from nuclear reactor analysis to boron neutron capture therapy. This study is designed to evaluate MCNP4A as the dose calculation system for photon-based radiotherapy applications. A graphical user interface (MCNP Radiation Therapy) has been developed which automatically sets up the geometry and photon source requirements for three-dimensional simulations using Computed Tomography (CT) data. Preliminary results suggest the code is capable of calculating satisfactory dose distributions in a variety of simulated homogeneous and heterogeneous phantoms. The major drawback for this dosimetry system is the amount of time to obtain a statistically significant answer. MCNPRT allows the user to analyze the performance of MCNP4A as a function of material, geometry resolution and MCNP4A photon and electron physics parameters. A typical simulation geometry consists of a 10 MV photon point source incident on a 15 x 15 x 15 cm{sup 3} phantom composed of water voxels ranging in size from 10 x 10 x 10 mm{sup 3} to 2 x 2 x 2 mm{sup 3}. As the voxel size is decreased, a larger percentage of time is spent tracking photons through the voxelized geometry as opposed to the secondary electrons. A PRPR Patch file is under development that will optimize photon transport within the simulation phantom specifically for radiotherapy applications. MCNP4A also supports parallel processing capabilities via the Parallel Virtual Machine (PVM) message passing system. A dedicated network of five SUN SPARC2 processors produced a wall-clock speedup of 4.4 based on a simulation phantom containing 5 x 5 x 5 mm{sup 3} water voxels. The code was also tested on the 80 node IBM RS/6000 cluster at the Maui High Performance Computing Center (NHPCC). A non-dedicated system of 75 processors produces a wall clock speedup of 29 relative to one SUN SPARC2 computer.

  15. Deterministic photon kerma distribution based on the Boltzmann equation for external beam radiation therapy

    SciTech Connect

    Yuan Jiankui; Jette, David; Chen Weimin

    2008-09-15

    A photon transport algorithm for fully three-dimensional radiotherapy treatment planning has been developed based on the discrete ordinates (S{sub N}) solution of the Boltzmann equation. The algorithm is characterized by orthogonal adaptive meshes, which place additional points where large gradients occur and a procedure to evaluate the collided flux using the representation of spherical harmonic expansion instead of the summation of the volume-weighted contribution from discrete angles. The Boltzmann equation was solved in the form of S{sub N} spatial, energy, and angular discretization with mitigation of ray effects by the first-collision source method. Unlike existing S{sub N} codes, which were designed for general purpose for multiparticle transport in areas such as nuclear engineering, our code is optimized for medical radiation transport. To validate the algorithm, several examples were employed to calculate the photon flux distribution. Numerical results show good agreement with the Monte Carlo calculations using EGSnrc.

  16. Variation in Use of Androgen Suppression With External-Beam Radiotherapy for Nonmetastatic Prostate Cancer

    SciTech Connect

    Swisher-McClure, Samuel; Pollack, Craig E.; Christodouleas, John P.; Guzzo, Thomas J.; Haas, Naomi B.; Vapiwala, Neha; Bekelman, Justin E.

    2012-05-01

    Purpose: To describe practice patterns associated with androgen suppression (AS) stratified by disease risk group in patients undergoing external-beam radiotherapy (EBRT) for localized prostate cancer. Methods and Materials: We identified 2,184 low-risk, 2,339 intermediate-risk, and 2,897 high-risk patients undergoing EBRT for nonmetastatic prostate cancer diagnosed between January 1, 2004, and December 31, 2005, in the linked Surveillance, Epidemiology, and End Results-Medicare database. We examined the association of patient, clinical, and demographic characteristics with AS use by multivariate logistic regression. Results: The proportions of patients receiving AS for low-risk, intermediate-risk, and high-risk prostate cancer were 32.2%, 56.3%, and 81.5%, respectively. AS use among men in the low-risk disease category varied widely, ranging from 13.6% in Detroit to 47.8% in Kentucky. We observed a significant decline in AS use between 2004 and 2005 within all three disease risk categories. Men aged {>=}75 years or with elevated comorbidity levels were more likely to receive AS. Conclusion: Our results identified apparent overuse and underuse of AS among men within the low-risk and high-risk disease categories, respectively. These results highlight the need for clinician and patient education regarding the appropriate use of AS. Practice patterns among intermediate-risk patients reflect the clinical heterogeneity of this population and underscore the need for better evidence to guide the treatment of these patients.

  17. Evaluation of target dose based on water-equivalent thickness in external beam radiotherapy

    PubMed Central

    Moghaddam, Behnaz Ghanbar; Vahabi-Moghaddam, Masoud; Sadremomtaz, Alireza

    2013-01-01

    In vivo dosimetry was carried out for 152 patients receiving external beam radiotherapy and the treatment sites were divided into two main groups: Thorax, Abdomen, and Pelvic (120 fields) and Head and Neck (52 fields). Combined entrance and exit dose measurements were performed using LiF: Mg, Cu, P thermoluminescent dosimeters (TLDs). Water-equivalent (effective) thicknesses and target dose were evaluated using dose transmission data. The ratio of measured to expected value for each quantity was considered as an indicator for the accuracy of the parameter. The average ratio of the entrance dose was evaluated as 1.01 ± 0.07. In the diameter measurement, the mean ratio of effective depth divided by the contour depth is 1.00 ± 0.13 that shows a wide distribution which reflects the influence of contour inaccuracies as well as tissue inhomogeneities. At the target level, the mean ratio of measured to the prescribed dose is 1.00 ± 0.07. According to our findings, the difference between effective depth and patient depth has a direct relation to target dose discrepancies. There are some inevitable sources which may cause the difference. Evaluation and application of effective diameter in treatment calculations would lead to a more reliable target dose, especially for fields which involve Thorax, Abdomen, and Pelvic. PMID:23532059

  18. Time of Decline in Sexual Function After External Beam Radiotherapy for Prostate Cancer

    SciTech Connect

    Siglin, Joshua; Kubicek, Gregory J.; Leiby, Benjamin; Valicenti, Richard K.

    2010-01-15

    Purpose: Erectile dysfunction is one of the most concerning toxicities for patients in the treatment of prostate cancer. The inconsistent evaluation of sexual function (SF) and limited follow-up data have necessitated additional study to clarify the rate and timing of erectile dysfunction after external beam radiotherapy (EBRT) for prostate cancer. Methods and Materials: A total of 143 men completed baseline data on SF before treatment and at the subsequent follow-up visits. A total of 1187 validated SF inventories were analyzed from the study participants. Multiple domains of SF (sex drive, erectile function, ejaculatory function, and overall satisfaction) were analyzed for <=8 years of follow-up. Results: The median follow-up was 4.03 years. The strongest predictor of SF after EBRT was SF before treatment. For all domains of SF, the only statistically significant decrease in function occurred in the first 24 months after EBRT. SF stabilized 2 years after treatment completion, with no statistically significant change in any area of SF >2 years after the end of EBRT. Conclusion: These data suggest that SF does not have a continuous decline after EBRT. Instead, SF decreases maximally within the first 24 months after EBRT, with no significant changes thereafter.

  19. Stage II endometrial carcinoma treated with external-beam radiotherapy, intracavitary application of cesium, and surgery

    SciTech Connect

    Podczaski, E.S.; Kaminski, P.; Manetta, A.; Louk, D.; Andrews, C.; Larson, J.; DeGeest, K.; Mortel, R. )

    1989-11-01

    From September 1972 to September 1987, thirty-six patients with stage II carcinoma of the endometrium were treated with external-beam radiotherapy to the pelvis, a single intracavitary application of cesium-137, and extrafascial hysterectomy with adnexectomy. Patients were followed for a median of 54.4 months. Overall 2- and 5-year actuarial survival rates were 83 and 58%, respectively. Survival was analyzed in terms of the independent variables surgical stage, presence of a gross cervical lesion, and residual disease within the myometrium or cervix. Factors contributing to patients survival were analyzed by the log-rank method. The 12 patients with a gross cervical lesion had an adverse prognosis, as compared to those without such a lesion (P less than 0.05). Seven of the twelve patients (58%) with a cervical lesion at clinical staging demonstrated persistent or recurrent disease. The presence of extrauterine disease at surgery was a major prognostic factor in patient survival (P less than 0.01). All six patients with extrauterine disease expired 2.3 to 53.0 months after hysterectomy. Two patients with persistence of disease expired 2.3 and 7.5 months after hysterectomy. Eleven patients developed recurrent disease 2.1 to 56.5 months after hysterectomy. All presented with distant metastases. Four of the thirteen patients with persistent or recurrent disease had no residual tumor within the myometrium.

  20. Respiratory gating for proton beam scanning versus photon 3D-CRT for breast cancer radiotherapy.

    PubMed

    Flejmer, Anna M; Edvardsson, Anneli; Dohlmar, Frida; Josefsson, Dan; Nilsson, Mats; Witt Nyström, Petra; Dasu, Alexandru

    2016-05-01

    Background Respiratory gating and proton therapy have both been proposed to reduce the cardiopulmonary burden in breast cancer radiotherapy. This study aims to investigate the additional benefit of proton radiotherapy for breast cancer with and without respiratory gating. Material and methods Twenty left-sided patients were planned on computed tomography (CT)-datasets acquired during enhanced inspiration gating (EIG) and free-breathing (FB), using photon three-dimensional conformal radiation therapy (3D-CRT) and scanned proton beams. Ten patients received treatment to the whole breast only (WBO) and 10 were treated to the breast and the regional lymph nodes (BRN). Dosimetric parameters characterizing the coverage of target volumes and the cardiopulmonary burden were compared using a paired, two-tailed Student's t-test. Results Protons ensured comparable or better target coverage than photons in all patients during both EIG and FB. The heterogeneity index decreased from 12% with photons to about 5% with protons. The mean dose to the ipsilateral lung was reduced in BRN patients from 12 Gy to 7 Gy  (RBE) in EIG and from 14 Gy to 6-7 Gy (RBE) in FB, while for WBO patients all values were about 5-6 Gy (RBE). The mean dose to heart decreased by a factor of four in WBO patients [from 1.1 Gy to 0.3 Gy (RBE) in EIG and from 2.1 Gy to 0.5 Gy (RBE) in FB] and 10 in BRN patients [from 2.1 Gy to 0.2 Gy (RBE) in EIG and from 3.4 Gy to 0.3 Gy (RBE) in FB]. Similarly, the mean and the near maximum dose to the left anterior descending artery (LAD) were significantly lower (p < 0.05) with protons in comparison with photons. Conclusion Proton spot scanning has a high potential to reduce the irradiation of organs at risk and other normal tissues for most patients, beyond what could be achieved with EIG and photon therapy. The largest dose sparing has been seen for BRN patients, both in terms of cardiopulmonary burden and integral dose. PMID:27027913

  1. Magnetic confinement of electron and photon radiotherapy dose: A Monte Carlo simulation with a nonuniform longitudinal magnetic field

    SciTech Connect

    Chen Yu; Bielajew, Alex F.; Litzenberg, Dale W.; Moran, Jean M.; Becchetti, Frederick D.

    2005-12-15

    It recently has been shown experimentally that the focusing provided by a longitudinal nonuniform high magnetic field can significantly improve electron beam dose profiles. This could permit precise targeting of tumors near critical areas and minimize the radiation dose to surrounding healthy tissue. The experimental results together with Monte Carlo simulations suggest that the magnetic confinement of electron radiotherapy beams may provide an alternative to proton or heavy ion radiation therapy in some cases. In the present work, the external magnetic field capability of the Monte Carlo code PENELOPE was utilized by providing a subroutine that modeled the actual field produced by the solenoid magnet used in the experimental studies. The magnetic field in our simulation covered the region from the vacuum exit window to the phantom including surrounding air. In a longitudinal nonuniform magnetic field, it is observed that the electron dose can be focused in both the transverse and longitudinal directions. The measured dose profiles of the electron beam are generally reproduced in the Monte Carlo simulations to within a few percent in the region of interest provided that the geometry and the energy of the incident electron beam are accurately known. Comparisons for the photon beam dose profiles with and without the magnetic field are also made. The experimental results are qualitatively reproduced in the simulation. Our simulation shows that the excessive dose at the beam entrance is due to the magnetic field trapping and focusing scattered secondary electrons that were produced in the air by the incident photon beam. The simulations also show that the electron dose profile can be manipulated by the appropriate control of the beam energy together with the strength and displacement of the longitudinal magnetic field.

  2. Monte Carlo source model for photon beam radiotherapy: photon source characteristics

    SciTech Connect

    Fix, Michael K.; Keall, Paul J.; Dawson, Kathryn; Siebers, Jeffrey V.

    2004-11-01

    A major barrier to widespread clinical implementation of Monte Carlo dose calculation is the difficulty in characterizing the radiation source within a generalized source model. This work aims to develop a generalized three-component source model (target, primary collimator, flattening filter) for 6- and 18-MV photon beams that match full phase-space data (PSD). Subsource by subsource comparison of dose distributions, using either source PSD or the source model as input, allows accurate source characterization and has the potential to ease the commissioning procedure, since it is possible to obtain information about which subsource needs to be tuned. This source model is unique in that, compared to previous source models, it retains additional correlations among PS variables, which improves accuracy at nonstandard source-to-surface distances (SSDs). In our study, three-dimensional (3D) dose calculations were performed for SSDs ranging from 50 to 200 cm and for field sizes from 1x1 to 30x30 cm{sup 2} as well as a 10x10 cm{sup 2} field 5 cm off axis in each direction. The 3D dose distributions, using either full PSD or the source model as input, were compared in terms of dose-difference and distance-to-agreement. With this model, over 99% of the voxels agreed within {+-}1% or 1 mm for the target, within 2% or 2 mm for the primary collimator, and within {+-}2.5% or 2 mm for the flattening filter in all cases studied. For the dose distributions, 99% of the dose voxels agreed within 1% or 1 mm when the combined source model--including a charged particle source and the full PSD as input--was used. The accurate and general characterization of each photon source and knowledge of the subsource dose distributions should facilitate source model commissioning procedures by allowing scaling the histogram distributions representing the subsources to be tuned.

  3. Monte Carlo simulation of photon buildup factors for shielding materials in radiotherapy x-ray facilities

    SciTech Connect

    Karim Karoui, Mohamed; Kharrati, Hedi

    2013-07-15

    Purpose: This paper presents the results of a series of calculations to determine buildup factors for ordinary concrete, baryte concrete, lead, steel, and iron in broad beam geometry for photons energies from 0.125 to 25.125 MeV at 0.250 MeV intervals.Methods: Monte Carlo N-particle radiation transport computer code has been used to determine the buildup factors for the studied shielding materials.Results: The computation of the primary broad beams using buildup factors data was done for nine published megavoltage photon beam spectra ranging from 4 to 25 MV in nominal energies, representing linacs made by the three major manufacturers. The first tenth value layer and the equilibrium tenth value layer are calculated from the broad beam transmission for these nine primary megavoltage photon beam spectra.Conclusions: The results, compared with published data, show the ability of these buildup factor data to predict shielding transmission curves for the primary radiation beam. Therefore, the buildup factor data can be combined with primary, scatter, and leakage x-ray spectra to perform computation of broad beam transmission for barriers in radiotherapy shielding x-ray facilities.

  4. Optical eye tracking system for real-time noninvasive tumor localization in external beam radiotherapy

    SciTech Connect

    Via, Riccardo Fassi, Aurora; Fattori, Giovanni; Fontana, Giulia; Pella, Andrea; Tagaste, Barbara; Ciocca, Mario; Riboldi, Marco; Baroni, Guido; Orecchia, Roberto

    2015-05-15

    Purpose: External beam radiotherapy currently represents an important therapeutic strategy for the treatment of intraocular tumors. Accurate target localization and efficient compensation of involuntary eye movements are crucial to avoid deviations in dose distribution with respect to the treatment plan. This paper describes an eye tracking system (ETS) based on noninvasive infrared video imaging. The system was designed for capturing the tridimensional (3D) ocular motion and provides an on-line estimation of intraocular lesions position based on a priori knowledge coming from volumetric imaging. Methods: Eye tracking is performed by localizing cornea and pupil centers on stereo images captured by two calibrated video cameras, exploiting eye reflections produced by infrared illumination. Additionally, torsional eye movements are detected by template matching in the iris region of eye images. This information allows estimating the 3D position and orientation of the eye by means of an eye local reference system. By combining ETS measurements with volumetric imaging for treatment planning [computed tomography (CT) and magnetic resonance (MR)], one is able to map the position of the lesion to be treated in local eye coordinates, thus enabling real-time tumor referencing during treatment setup and irradiation. Experimental tests on an eye phantom and seven healthy subjects were performed to assess ETS tracking accuracy. Results: Measurements on phantom showed an overall median accuracy within 0.16 mm and 0.40° for translations and rotations, respectively. Torsional movements were affected by 0.28° median uncertainty. On healthy subjects, the gaze direction error ranged between 0.19° and 0.82° at a median working distance of 29 cm. The median processing time of the eye tracking algorithm was 18.60 ms, thus allowing eye monitoring up to 50 Hz. Conclusions: A noninvasive ETS prototype was designed to perform real-time target localization and eye movement monitoring

  5. A feasibility study of using couch-based real time dosimetric device in external beam radiotherapy

    SciTech Connect

    Prabhakar, Ramachandran; Cramb, Jim; Kron, Tomas

    2011-12-15

    Purpose: Measurement of actual dose delivered during radiotherapy treatment aids in checking the accuracy of dose delivered to the patient. In this study, a couch-based real time dosimetric device has been proposed to measure the exit or entrance dose to a patient during external beam radiotherapy. The utility and feasibility of such a device using a 2D array of diodes has been demonstrated. Methods: Two MAPCHECK devices: MAPCHECK (1175) and MAPCHECK 2 (both SunNuclear) were embedded in a foam block in the treatment couch of a Varian 21iX linear accelerator. The angular dependence of the detector response for both devices was studied before implementing the MAPCHECKs for experimental purposes. An Alderson Rando head phantom was scanned with the MAPCHECK and MAPCHECK 2 devices separately and four different treatment plans were generated with target volumes at three different positions simulating typical clinical situations. The analytical anisotropic algorithm (AAA) was used to compute the doses in an Eclipse treatment planning system (Varian Medical Systems). The Rando phantom with the MAPCHECK device was exposed in Clinac 21iX linear accelerator. The measured dose distribution was compared with the calculated dose distribution to check for the accuracy in dose delivery. Results: Measured and computed dose distribution were found to agree with more than 93% of pixels passing at 3% and 3 mm gamma criteria for all the treatment plans. The couch-based real time dosimetry system may also be applied for noncoplanar beams where electronic portal imaging device (EPID) is not practical to measure the dose. Other advantages include checking the beam stability during the patient treatment, performing routine morning quality assurance (QA) tests in the linear accelerator, and to perform pretreatment verification of intensity modulated radiation therapy (IMRT). One of the drawbacks of this system is that it cannot be used for measuring the dose at 90 deg. or 270 deg. gantry

  6. Two-Photon Frequency Comb Excitation of Rubidium Atoms in External Magnetic Field

    NASA Astrophysics Data System (ADS)

    Vujičić, N.; Ban, T.; Skenderović, H.; Vdović, S.; Pichler, G.

    2008-10-01

    In the present experiment the 5S-5D two-photon transitions in 85Rb and 87Rb atoms as a result of the interaction of the femtosecond frequency comb with atomic levels of both rubidium isotopes are investigated. The main problem in studying of two-photon transitions is in optimization of the excitation efficiency of the desired state. There are two general cases: those transition with an intermediate resonance those in which the pulse spectrum is far detuned from an intermediate resonance. In order to investigate the dependence of the two-photon fluorescence signal as a result of interaction of the frequency comb with perturbed energy-level pattern an external magnetic field was applied.

  7. Modelocked external-cavity semiconductor laser noise characterization and application to photonic arbitrary waveform generation

    NASA Astrophysics Data System (ADS)

    Yilmaz, Tolga

    There are several applications of low-noise, coherent optical frequency combs generated by modelocked lasers. One application is to use the optical comb source in a photonic arbitrary waveform generator. Performance of electronic arbitrary waveform generators is hindered by the speed and linearity limitations of digital-to-analog converters. These limitations may be overcome by the use of high-bandwidth optical techniques. This thesis investigates the possibility of using actively and hybridly modelocked external-cavity semiconductor lasers to improve upon the speed limitations of electronic arbitrary waveform generators. Pulsetrain noise properties have been studied for different cavity geometries and semiconductor gain medium types. Modelocked laser optical frequency comb stabilization has been achieved and it has made it possible to use the laser in a photonic arbitrary waveform generator architecture. The potential for arbitrary waveform generation and photonic synthesis has been demonstrated by the generated waveforms at microwave frequencies.

  8. Boosting runtime-performance of photon pencil beam algorithms for radiotherapy treatment planning.

    PubMed

    Siggel, M; Ziegenhein, P; Nill, S; Oelfke, U

    2012-10-01

    Pencil beam algorithms are still considered as standard photon dose calculation methods in Radiotherapy treatment planning for many clinical applications. Despite their established role in radiotherapy planning their performance and clinical applicability has to be continuously adapted to evolving complex treatment techniques such as adaptive radiation therapy (ART). We herewith report on a new highly efficient version of a well-established pencil beam convolution algorithm which relies purely on measured input data. A method was developed that improves raytracing efficiency by exploiting the capability of modern CPU architecture for a runtime reduction. Since most of the current desktop computers provide more than one calculation unit we used symmetric multiprocessing extensively to parallelize the workload and thus decreasing the algorithmic runtime. To maximize the advantage of code parallelization, we present two implementation strategies - one for the dose calculation in inverse planning software, and one for traditional forward planning. As a result, we could achieve on a 16-core personal computer with AMD processors a superlinear speedup factor of approx. 18 for calculating the dose distribution of typical forward IMRT treatment plans. PMID:22071169

  9. A dosimetric intercomparison of megavoltage photon beams in UK radiotherapy centres.

    PubMed

    Thwaites, D I; Williams, J R; Aird, E G; Klevenhagen, S C; Williams, P C

    1992-02-01

    A dosimetry intercomparison has been carried out for all 64 radiotherapy centres in the UK. Doses were measured with an ionization chamber in an epoxy resin water-substitute phantom of relatively simple geometry. Reference-point measurements were made for all MV photon beams. For 61 Co-60 beams, a mean ratio of measured-to-stated dose of 1.002 was observed with a standard deviation of 0.014, whilst for 100 MV x-ray beams, the corresponding figures were 1.003 and 0.015. 97% of beams lay within a +/- 3% deviation. One measurement was instrumental in discovering a large discrepancy. Doses were also investigated in two planned three-field distributions at one beam quality in each centre. One of these was in a homogeneous phantom, whilst the second included a lung-equivalent insert. Doses were measured at the central point and at four other points in the high dose volume. In both situations, the mean ratio of measured-to-calculated doses for all points was 1.008, with standard deviations of 0.027 and 0.035 for the uniform and non-uniform phantoms, respectively. Discrepancies over 5% were followed up. The work must be viewed in the context of other international intercomparisons and is an essential part of wider radiotherapy audit processes. PMID:1553393

  10. Dose-rate conversion factors for external exposure to photons and electrons

    SciTech Connect

    Kocher, D.C.

    1981-08-01

    Dose-rate conversion factors for external exposure to photons and electrons have been calculated for approximately 500 radionuclides of potential importance in environmental radiological assessments. The dose-rate factors were obtained using the DOSFACTER computer code. The results given in this report incorporate calculation of electron dose-rate factors for radiosensitive tissues of the skin, improved estimates of organ dose-rate factors for photons, based on organ doses for monoenergetic sources at the body surface of an exposed individual, and the spectra of scattered photons in air from monoenergetic sources in an infinite, uniformly contaminated atmospheric cloud, calculation of dose-rate factors for other radionuclides in addition to those of interest in the nuclear fuel cycle, and incorporation of updated radioactive decay data for all radionuclides. Dose-rate factors are calculated for three exposure modes - immersion in contaminated air, immersion in contaminated water, and exposure at a height of 1 m above a contaminated ground surface. The report presents the equations used to calculate the external dose-rate factors for photons and electrons, documentation of the revised DOSFACTER computer code, and a complete tabulation of the calculated dose-rate factors. 30 refs., 12 figs.

  11. Multivariate analyses of locoregional recurrences and skin complications after postmastectomy radiotherapy using electrons or photons

    SciTech Connect

    Huang, E.-Y.; Chen, H.-C.; Sun, L.-M.; Fang, F.-M.; Hsu, H.-C.; Hsiung, C.-Y.; Huang, Y.-J.; Wang, C.-Y.; Wang, C.-J. . E-mail: cjw1010@adm.cgmh.org.tw

    2006-08-01

    Purpose: We retrospectively analyzed factors of locoregional (LR) recurrence and skin complications in patients after postmastectomy radiotherapy (PMRT). Methods and Materials: From January 1988 to December 1999, a total of 246 women with Stage II and III breast cancer received PMRT. Doses of 46 to 52.2 Gy/23 to 29 fractions were delivered to the chest wall (CW) and peripheral lymphatic drainage with 12 to 15 MeV single-portal electrons or 6MV photons. Of the patients, 84 patients received an additional 6 to 20 Gy boost to the surgical scar using 9 MeV electrons. We used the Cox regression model for multivariate analyses of CW, supraclavicular nodes (SCN), and LR recurrence. Results: N3 stage (positive nodes >9) (p = 0.003) and diabetes (p = 0.004) were independent factors of CW recurrence. Analysis of ipsilateral SCN recurrence showed that N3 stage (p < 0.001) and electrons (p = 0.006) were independent factors. For LR recurrence, N3 (p < 0.001), T3 to T4 (p = 0.033) and electrons (p = 0.003) were significant factors. Analysis of skin telangiectasia revealed that electrons (p < 0.001) and surgical scar boost (p = 0.003) were independent factors. Conclusions: Photons are superior to single-portal electrons in patients receiving postmastectomy radiotherapy because of better locoregional control and less skin telangiectasia. In patients in whom the number of positive axillary nodes is >9, more aggressive treatment may be considered for better locoregional control.

  12. Retinoblastoma-comparative analysis of external radiotherapy techniques, including an IMRT technique

    SciTech Connect

    Reisner, Marcio Lemberg . E-mail: mreisner@uol.com.br; Viegas, Celia Maria Pais; Grazziotin, Rachele Zanchet; Santos Batista, Delano Valdivino; Carneiro, Tulio Meneses; Mendonca de Araujo, Carlos Manoel; Marchiori, Edson

    2007-03-01

    Purpose: To compare the numerous external radiotherapy (RT) techniques for the treatment of retinoblastoma, as well as an intensity-modulated RT (IMRT) technique. The latter was elaborated to evaluate the potential dose reduction in the surrounding tissue, as well as the potential avoidance of subdosage in the ora serrata retinae. Methods and Materials: A 2-year-old patient with unilateral retinoblastoma underwent CT. With the aid of an ophthalmologist, the ocular structures were delimited, and 13 techniques described in published reports were reproduced on three-dimensional planning software and identified according to their authors. A technique with four noncoplanar fields using IMRT was also elaborated. These techniques were compared according to the dose to the ora serrata retinae, lens, orbit (volume that received a dose of {>=}20 Gy), vitreous, optic nerve, lacrimal gland (volume that received a dose of {>=}34 Gy), and cornea and according to their ease of reproducibility. Results: The techniques that attained the therapeutic dose to the ora serrata retinae were the IMRT technique and the techniques of Haye, Cassady, Cormack, and al-Beteri. The Cormack technique had the lowest volume that received a dose of {>=}20 Gy in the orbit, followed by the IMRT technique. The IMRT technique also achieved the lowest volume that received a dose of {>=}34 Gy (14%) in the lacrimal gland. The Abramson/McCormick/Blach, Cassady, Reese, and Schipper techniques were the easiest to reproduce and the Chin the most complex. Conclusion: Retinoblastoma treatment with IMRT has an advantage over the other techniques, because it allows for the greatest reduction of dose to the orbit and lacrimal gland, while maintaining the therapeutic dose to the ora serrata retinae and vitreous.

  13. Unified registration framework for cumulative dose assessment in cervical cancer across external beam radiotherapy and brachytherapy

    NASA Astrophysics Data System (ADS)

    Roy, Sharmili; Totman, John J.; Choo, Bok A.

    2016-03-01

    Dose accumulation across External Beam Radiotherapy (EBRT) and Brachytherapy (BT) treatment fractions in cervical cancer is extremely challenging due to structural dissimilarities and large inter-fractional anatomic deformations between the EBRT and BT images. The brachytherapy applicator and the bladder balloon, present only in the BT images, introduce missing structural correspondences for the underlying registration problem. Complex anatomical deformations caused by the applicator and the balloon, different rectum and bladder filling and tumor shrinkage compound the registration difficulties. Conventional free-form registration methods struggle to handle such topological differences. In this paper, we propose a registration pipeline that first transforms the original images to their distance maps based on segmentations of critical organs and then performs non-linear registration of the distance maps. The resulting dense deformation field is then used to transform the original anatomical image. The registration accuracy is evaluated on 27 image pairs from stage 2B-4A cervical cancer patients. The algorithm reaches a Hausdorff distance of close to 0:5 mm for the uterus, 2:2 mm for the bladder and 1:7 mm for the rectum when applied to (EBRT,BT) pairs, taken at time points more than three months apart. This generalized model-free framework can be used to register any combination of EBRT and BT images as opposed to methods in the literature that are tuned for either only (BT,BT) pair, or only (EBRT,EBRT) pair or only (BT,EBRT) pair. A unified framework for 3D dose accumulation across multiple EBRT and BT fractions is proposed to facilitate adaptive personalized radiation therapy.

  14. CAPRA-S predicts outcome for adjuvant and salvage external beam radiotherapy after radical prostatectomy

    PubMed Central

    Zimmermann, Michel; Delouya, Guila; Alenizi, Abdullah M.; Rajih, Emad; Zorn, Kevin C.; Taussky, Daniel

    2016-01-01

    Introduction: We aimed to evaluate the predictive value of the Cancer of the Prostate Risk Assessment Postsurgical Score (CAPRA-S) for patients treated with radical prostatectomy followed by subsequent external beam radiotherapy (EBRT). Methods: A total of 373 patients treated with EBRT between January 2000 and June 2015 were identified in the institutional database. Followup and complete CAPRA-S score were available for 334 (89.5%) patients. CAPRA-S scores were sorted into previously defined categories of low- (score 0–2), intermediate- (3–5), and high-risk (6–12). Time to biochemical recurrence (BCR) was defined as prostate-specific antigen (PSA) >0.20 ng/mL after EBRT. Survival analyses were performed using the Kaplan-Meier method and comparisons were made using the log-rank test. Results: Overall median time from surgery to EBRT was 18 months (interquartile range [IQR] 8–36) and median followup since EBRT was 48 months (IQR 28–78). CAPRA-S predicted time to BCR (<0.001), time to palliative androgen-deprivation therapy (ADT) (p=0.017), and a trend for significantly predicting overall survival (OS, p=0.058). On multivariate analysis, the CAPRA-S was predictive of time to BCR only (low-risk vs. intermediate-risk; hazard ratio [HR] 0.14, 95% confidence interval [CI] 0.043–0.48, p=0.001). The last PSA measurement before EBRT as a continuous and grouped variable proved highly significant in predicting all outcomes tested, including OS (p≤0.002). Conclusions: CAPRA-S predicts time to BCR and freedom from palliative ADT, and is borderline significant for OS. Together with the PSA before EBRT, CAPRA-S is a useful, predictive tool. The main limitation of this study is its retrospective design. PMID:27217861

  15. Comparative Study of Inguinal Hernia Repair Rates After Radical Prostatectomy or External Beam Radiotherapy

    SciTech Connect

    Lughezzani, Giovanni; Sun, Maxine; Perrotte, Paul; Alasker, Ahmed; Jeldres, Claudio; Isbarn, Hendrik; Budaeus, Lars; Lattouf, Jean-Baptiste; Valiquette, Luc; Benard, Francois; Saad, Fred; Graefen, Markus; Montorsi, Francesco; Karakiewicz, Pierre I.

    2010-12-01

    Purpose: We tested the hypothesis that patients treated for localized prostate cancer with radical prostatectomy (RP) have a higher risk of requiring an inguinal hernia (IH) repair than their counterparts treated with external beam radiotherapy (EBRT). Methods and Materials: Within the Quebec Health Plan database, we identified 6,422 men treated with RP and 4,685 men treated with EBRT for localized prostate cancer between 1990 and 2000, in addition to 6,933 control patients who underwent a prostate biopsy. From among that population, we identified patients who underwent a unilateral or bilateral hernia repair after either RP or EBRT. Kaplan-Meier plots showed IH repair-free survival rates. Univariable and multivariable Cox regression models tested the predictors of IH repair after RP or EBRT. Covariates consisted of age, year of surgery, and Charlson Comorbidity Index. Results: IH repair-free survival rates at 1, 2, 5, and 10 years were 96.8, 94.3, 90.5, and 86.2% vs. 98.9, 98.0, 95.4, and 92.2%, respectively, in RP vs. EBRT patients (log-rank test, p < 0.001). IH repair-free survival rates in the biopsy population were 98.3, 97.1, 94.9, and 90.2% at the same four time points. In multivariable Cox regression models, RP predisposed to a 2.3-fold higher risk of IH repair than EBRT (p < 0.001). Besides therapy type, patient age (p < 0.001) represented the only other independent predictor of IH repair. Conclusions: RP predisposes to a higher rate of IH repair relative to EBRT. This observation should be considered at informed consent.

  16. Fractionated External Beam Radiotherapy as a Suitable Preparative Regimen for Hepatocyte Transplantation After Partial Hepatectomy

    SciTech Connect

    Krause, Petra; Wolff, Hendrik A.; Rave-Frank, Margret; Schmidberger, Heinz; Becker, Heinz; Hess, Clemens Friedrich; Christiansen, Hans; Koenig, Sarah

    2011-07-15

    Purpose: Hepatocyte transplantation is strongly considered to be a promising option to correct chronic liver failure through repopulation of the diseased organ. We already reported on extensive liver repopulation by hepatocytes transplanted into rats preconditioned with 25-Gy single dose selective external beam irradiation (IR). Herein, we tested lower radiation doses and fractionated protocols, which would be applicable in clinical use. Methods and Material: Livers of dipeptidylpeptidase IV (DPPIV)-deficient rats were preconditioned with partial liver external beam single dose IR at 25 Gy, 8 Gy, or 5 Gy, or fractionated IR at 5 x 5 Gy or 5 x 2 Gy. Four days after completion of IR, a partial hepatectomy (PH) was performed to resect the untreated liver section. Subsequently, 12 million wild-type (DPPIV{sup +}) hepatocytes were transplanted via the spleen into the recipient livers. The degree of donor cell integration and liver repopulation was studied 16 weeks after transplantation by means of immunofluorescence and DPPIV-luminescence assay. Results: Donor hepatocyte integration and liver repopulation were more effective in the irradiated livers following pretreatment with the IR doses 1 x 25 Gy and 5 x 5 Gy (formation of large DPPIV-positive cell clusters) than single-dose irradiation at 8 Gy or 5 Gy (DPPIV-positive clusters noticeably smaller and less frequent). Quantitative analysis of extracted DPPIV revealed signals exceeding the control level in all transplanted animals treated with IR and PH. Compared with the standard treatment of 1 x 25 Gy, fractionation with 5 x 5 Gy was equally efficacious, the Mann-Whitney U test disclosing no statistically significant difference (p = 0.146). The lower doses of 1 x 5 Gy, 1 x 8 Gy, and 5 x 2 Gy were significantly less effective with p < 0.05. Conclusion: This study suggests that fractionated radiotherapy in combination with PH is a conceivable pretreatment approach to prime the host liver for hepatocyte transplantation

  17. Optimum location of external markers using feature selection algorithms for real-time tumor tracking in external-beam radiotherapy: a virtual phantom study.

    PubMed

    Nankali, Saber; Esmaili Torshabi, Ahmad; Samadi Miandoab, Payam; Baghizadeh, Amin

    2016-01-01

    In external-beam radiotherapy, using external markers is one of the most reliable tools to predict tumor position, in clinical applications. The main challenge in this approach is tumor motion tracking with highest accuracy that depends heavily on external markers location, and this issue is the objective of this study. Four commercially available feature selection algorithms entitled 1) Correlation-based Feature Selection, 2) Classifier, 3) Principal Components, and 4) Relief were proposed to find optimum location of external markers in combination with two "Genetic" and "Ranker" searching procedures. The performance of these algorithms has been evaluated using four-dimensional extended cardiac-torso anthropomorphic phantom. Six tumors in lung, three tumors in liver, and 49 points on the thorax surface were taken into account to simulate internal and external motions, respectively. The root mean square error of an adaptive neuro-fuzzy inference system (ANFIS) as prediction model was considered as metric for quantitatively evaluating the performance of proposed feature selection algorithms. To do this, the thorax surface region was divided into nine smaller segments and predefined tumors motion was predicted by ANFIS using external motion data of given markers at each small segment, separately. Our comparative results showed that all feature selection algorithms can reasonably select specific external markers from those segments where the root mean square error of the ANFIS model is minimum. Moreover, the performance accuracy of proposed feature selection algorithms was compared, separately. For this, each tumor motion was predicted using motion data of those external markers selected by each feature selection algorithm. Duncan statistical test, followed by F-test, on final results reflected that all proposed feature selection algorithms have the same performance accuracy for lung tumors. But for liver tumors, a correlation-based feature selection algorithm, in

  18. Macro-step Monte Carlo Methods and their Applications in Proton Radiotherapy and Optical Photon Transport

    NASA Astrophysics Data System (ADS)

    Jacqmin, Dustin J.

    Monte Carlo modeling of radiation transport is considered the gold standard for radiotherapy dose calculations. However, highly accurate Monte Carlo calculations are very time consuming and the use of Monte Carlo dose calculation methods is often not practical in clinical settings. With this in mind, a variation on the Monte Carlo method called macro Monte Carlo (MMC) was developed in the 1990's for electron beam radiotherapy dose calculations. To accelerate the simulation process, the electron MMC method used larger steps-sizes in regions of the simulation geometry where the size of the region was large relative to the size of a typical Monte Carlo step. These large steps were pre-computed using conventional Monte Carlo simulations and stored in a database featuring many step-sizes and materials. The database was loaded into memory by a custom electron MMC code and used to transport electrons quickly through a heterogeneous absorbing geometry. The purpose of this thesis work was to apply the same techniques to proton radiotherapy dose calculation and light propagation Monte Carlo simulations. First, the MMC method was implemented for proton radiotherapy dose calculations. A database composed of pre-computed steps was created using MCNPX for many materials and beam energies. The database was used by a custom proton MMC code called PMMC to transport protons through a heterogeneous absorbing geometry. The PMMC code was tested against MCNPX for a number of different proton beam energies and geometries and proved to be accurate and much more efficient. The MMC method was also implemented for light propagation Monte Carlo simulations. The widely accepted Monte Carlo for multilayered media (MCML) was modified to incorporate the MMC method. The original MCML uses basic scattering and absorption physics to transport optical photons through multilayered geometries. The MMC version of MCML was tested against the original MCML code using a number of different geometries and

  19. Radiogenic Side Effects After Hypofractionated Stereotactic Photon Radiotherapy of Choroidal Melanoma in 212 Patients Treated Between 1997 and 2007

    SciTech Connect

    Dunavoelgyi, Roman; Dieckmann, Karin; Gleiss, Andreas; Sacu, Stefan; Kircher, Karl; Georgopoulos, Michael; Georg, Dietmar; Zehetmayer, Martin; Poetter, Richard

    2012-05-01

    Purpose: To evaluate side effects of hypofractionated stereotactic photon radiotherapy for patients with choroidal melanoma. Patients and Methods: Two hundred and twelve patients with choroidal melanoma unsuitable for ruthenium-106 brachytherapy or local resection were treated stereotactically at the Medical University of Vienna between 1997 and 2007 with a Linac with 6-MV photon beams in five fractions with 10, 12, or 14 Gy per fraction. Examinations for radiogenic side effects were performed at baseline and every 3 months in the first 2 years, then every 6 months until 5 years and then once a year thereafter until 10 years after radiotherapy. Adverse side effects were assessed using slit-lamp examination, funduscopy, gonioscopy, tonometry, and, if necessary, fundus photography and fluorescein angiography. Evaluations of incidence of side effects are based on an actuarial analysis. Results: One hundred and eighty-nine (89.2%) and 168 (79.2%) of the tumors were within 3 mm of the macula and the optic disc, respectively. The five most common radiotherapy side effects were retinopathy and optic neuropathy (114 cases and 107 cases, respectively), cataract development (87 cases), neovascular glaucoma (46 cases), and corneal epithelium defects (41 cases). In total, 33.6%, 38.5%, 51.2%, 75.5%, and 77.6% of the patients were free of any radiation retinopathy, optic neuropathy, cataract, neovascular glaucoma, or corneal epithelium defects 5 years after radiotherapy, respectively. Conclusion: In centrally located choroidal melanoma hypofractionated stereotactic photon radiotherapy shows a low to moderate rate of adverse long-term side effects comparable with those after proton beam radiotherapy. Future fractionation schemes should seek to further reduce adverse side effects rate while maintaining excellent local tumor control.

  20. Intraoperative radiotherapy (IORT) combined with external beam radiotherapy (EBRT) for soft-tissue sarcomas – a retrospective evaluation of the Homburg experience in the years 1995–2007

    PubMed Central

    Niewald, Marcus; Fleckenstein, Jochen; Licht, Norbert; Bleuzen, Caroline; Ruebe, Christian

    2009-01-01

    Purpose To retrospectively evaluate the results after a regimen of surgery, IORT (intraoperative radiotherapy), and EBRT (external beam radiotherapy) for soft-tissue sarcomas Methods 38 consecutive patients underwent IORT for soft-tissue sarcoma; 29 were treated for primary tumours, 9 for recurrences. There were 14 cases with liposarcomas, 8 with leiomyosarcomas, 7 with malignant fibrous histiocytomas. 27/38 tumours were located in the extremities, the remaining ones in the retroperitoneum or the chest. Radical resection was attempted in all patients; a R0-resection was achieved in 15/38 patients, R1 in 12/38 pats and R2 in 4/38 pats. IORT was performed using a J-125 source and a HDR (high dose rate) afterloading machine after suturing silicone flaps to the tumour bed. The total dose applied ranged from 8–15 Gy/0.5 cm tissue depth measured from the flap surface. After wound healing external beam radiotherapy (EBRT) was applied in 31/38 patients with total doses of 23–56 Gy dependent on resection status and wound situation. The mean duration of follow-up was 2.3 years. Results A local recurrence was found in 10/36 patients, lymph node metastases in 2/35, and distant metastases in 6/35 patients. The actuarial local control rate was 63%/5 years. The overall survival rate was 57%/5 years. There was no statistically significant difference between the results after treatment for primaries or for recurrences. Late toxicity to the skin was found in 13/31 patients, wound healing problems in 5/31 patients. A neuropathy was never seen. Conclusion The combination of surgery, IORT, and EBRT yields favourable local control and survival data which are well within the range of the results reported in the literature. The complication rates, however, are considerable although the complications are not severe, they should be taken into account when therapy decisions are made. PMID:19709420

  1. An alternative approach to compensators design for photon beams used in radiotherapy

    NASA Astrophysics Data System (ADS)

    Jurković, S.; Žauhar, G.; Bistrović, M.; Faj, D.; Kaliman, Z.; Smilović Radojčić, Đ.

    2007-09-01

    The use of compensators in order to achieve desired dose distribution has a long history and is a well-established technique in radiation therapy planning. There are several different calculation methods for determining a compensator's thickness. An alternative method that is based on the Cunningham's modification of Clarkson's method to calculate scattered radiation in beams with an inhomogeneous cross-section is proposed. It is well known that the total dose distribution of radiotherapy photon beam consists of the contributions of the primary beam, attenuated by the tissue layer, and the scattered radiation generated by the primary radiation in single and multiple photon scatter events. The scattered component can be represented as a function of the primary radiation. The central point of our method is the numerical estimation of the primary distribution required to achieve the desired total distribution. Now using the calculated primary distribution, the shape of the modulator could be determined. In this way the contribution of the scattered component is validated in a more accurate way than using effective attenuation coefficients, which is a common practice. The method is verified in various clinical situations and compared with the standard method. The accuracy, although dependent on geometry, was improved by at least 2%. With more complex geometries there is an even higher gain in accuracy with our method when compared to the standard method.

  2. Accuracy of the photon and electron physics in GEANT4 for radiotherapy applications

    SciTech Connect

    Poon, Emily; Verhaegen, Frank

    2005-06-15

    This work involves a validation of the photon and electron transport of the GEANT4 particle simulation toolkit for radiotherapy physics applications. We examine the cross sections and sampling algorithms of the three electromagnetic physics models in version 4.6.1 of the toolkit: Standard, Low-energy, and Penelope. The depth dose distributions in water for incident monoenergetic and clinical beams are compared to the EGSNRC results. In photon beam simulations, all three models agree with EGSNRC to within 2%, except for the buildup region. Larger deviations are found for incident electron beams, and the differences are affected by user-imposed electron step limitations. Particle distributions through thin layers of clinical target materials, and perturbation effects near high-Z and low-Z interfaces are also investigated. The electron step size artifacts observed in our studies indicate potential problems with the condensed history algorithm. A careful selection of physics processes and transport parameters is needed for optimum efficiency and accuracy.

  3. Dose-distance metric that predicts late rectal bleeding in patients receiving radical prostate external-beam radiotherapy

    NASA Astrophysics Data System (ADS)

    Lee, Richard; Chan, Elisa K.; Kosztyla, Robert; Liu, Mitchell; Moiseenko, Vitali

    2012-12-01

    The relationship between rectal dose distribution and the incidence of late rectal complications following external-beam radiotherapy has been previously studied using dose-volume histograms or dose-surface histograms. However, they do not account for the spatial dose distribution. This study proposes a metric based on both surface dose and distance that can predict the incidence of rectal bleeding in prostate cancer patients treated with radical radiotherapy. One hundred and forty-four patients treated with radical radiotherapy for prostate cancer were prospectively followed to record the incidence of grade ≥2 rectal bleeding. Radiotherapy plans were used to evaluate a dose-distance metric that accounts for the dose and its spatial distribution on the rectal surface, characterized by a logistic weighting function with slope a and inflection point d0. This was compared to the effective dose obtained from dose-surface histograms, characterized by the parameter n which describes sensitivity to hot spots. The log-rank test was used to determine statistically significant (p < 0.05) cut-off values for the dose-distance metric and effective dose that predict for the occurrence of rectal bleeding. For the dose-distance metric, only d0 = 25 and 30 mm combined with a > 5 led to statistical significant cut-offs. For the effective dose metric, only values of n in the range 0.07-0.35 led to statistically significant cut-offs. The proposed dose-distance metric is a predictor of rectal bleeding in prostate cancer patients treated with radiotherapy. Both the dose-distance metric and the effective dose metric indicate that the incidence of grade ≥2 rectal bleeding is sensitive to localized damage to the rectal surface.

  4. Incorporating Androgen Deprivation With Dose-Escalated External-Beam Radiotherapy for Prostate Cancer.

    PubMed

    Dosoretz, Arie P; Yu, James B

    2016-05-20

    was concerned about the potential for greater urinary incontinence and/or urinary irritation associated with these treatments compared with external-beam radiotherapy (RT).(1,2). PMID:27001587

  5. Second cancer incidence risk estimates using BEIR VII models for standard and complex external beam radiotherapy for early breast cancer

    SciTech Connect

    Donovan, E. M.; James, H.; Bonora, M.; Yarnold, J. R.; Evans, P. M.

    2012-10-15

    Purpose: To compare organ specific cancer incidence risks for standard and complex external beam radiotherapy (including cone beam CT verification) following breast conservation surgery for early breast cancer.Method: Doses from breast radiotherapy and kilovoltage cone beam CT (CBCT) exposures were obtained from thermoluminescent dosimeter measurements in an anthropomorphic phantom in which the positions of radiosensitive organs were delineated. Five treatment deliveries were investigated: (i) conventional tangential field whole breast radiotherapy (WBRT), (ii) noncoplanar conformal delivery applicable to accelerated partial beast irradiation (APBI), (iii) two-volume simultaneous integrated boost (SIB) treatment, (iv) forward planned three-volume SIB, and (v) inverse-planned three volume SIB. Conformal and intensity modulated radiotherapy methods were used to plan the complex treatments. Techniques spanned the range from simple methods appropriate for patient cohorts with a low cancer recurrence risk to complex plans relevant to cohorts with high recurrence risk. Delineated organs at risk included brain, salivary glands, thyroid, contralateral breast, left and right lung, esophagus, stomach, liver, colon, and bladder. Biological Effects of Ionizing Radiation (BEIR) VII cancer incidence models were applied to the measured mean organ doses to determine lifetime attributable risk (LAR) for ages at exposure from 35 to 80 yr according to radiotherapy techniques, and included dose from the CBCT imaging. Results: All LAR decreased with age at exposure and were lowest for brain, thyroid, liver, and bladder (<0.1%). There was little dependence of LAR on radiotherapy technique for these organs and for colon and stomach. LAR values for the lungs for the three SIB techniques were two to three times those from WBRT and APBI. Uncertainties in the LAR models outweigh any differences in lung LAR between the SIB methods. Constraints in the planning of the SIB methods ensured that

  6. Second Cancer Incidence Risk Estimates using BEIR VII Models for Standard and Complex External Beam Radiotherapy for Early Breast Cancer

    PubMed Central

    Donovan, E M; James, H; Bonora, M; Yarnold, JR; Evans, PM

    2012-01-01

    Purpose To compare organ specific cancer incidence risks for standard and complex external beam radiotherapy including cone beam CT verification following breast conservation surgery for early breast cancer. Method Doses from breast radiotherapy and kilovoltage cone beam CT (CBCT) exposures were obtained from thermoluminescent dosimeter (TLD) measurements in an anthropomorphic phantom in which the positions of radiosensitive organs were delineated. Five treatment deliveries were investigated : (i) conventional tangential field whole breast radiotherapy (WBRT), (ii) non-coplanar conformal delivery applicable to accelerated partial beast irradiation (APBI), (iii) two-volume simultaneous integrated boost (SIB) treatment, (iv) forward planned three-volume SIB, (v) inverse-planned three volume SIB. Conformal and intensity modulated radiotherapy (IMRT) methods were used to plan the complex treatments. Techniques spanned the range from simple methods appropriate for patient cohorts with a low local cancer recurrence risk to complex plans relevant to cohorts with high recurrence risk. Delineated organs at risk included brain, salivary glands, thyroid, contra-lateral breast, left and right lung, oesophagus, stomach, liver, colon and bladder. Biological Effects of Ionising Radiation (BEIR) VII cancer incidence models were applied to the measured mean organ doses to determine Lifetime Attributable Risk (LAR) for ages at exposure from 35 to 80 years according to radiotherapy techniques, and included dose from the CBCT imaging. Results All LAR decreased with age at exposure and were lowest for brain, thyroid, liver and bladder (< 0.1%). There was little dependence of LAR on radiotherapy technique for these organs and for colon and stomach. LAR values for the lungs for the three SIB techniques were two to three times those from WBRT and APBI. Uncertainties in the LAR models outweigh any differences in lung LAR between the SIB methods. Constraints in the planning of the SIB

  7. Craniospinal Irradiation Techniques: A Dosimetric Comparison of Proton Beams With Standard and Advanced Photon Radiotherapy

    SciTech Connect

    Yoon, Myonggeun; Shin, Dong Ho; Kim, Jinsung; Kim, Jong Won; Kim, Dae Woong; Park, Sung Yong; Lee, Se Byeong; Kim, Joo Young; Park, Hyeon-Jin; Park, Byung Kiu; Shin, Sang Hoon

    2011-11-01

    Purpose: To evaluate the dosimetric benefits of advanced radiotherapy techniques for craniospinal irradiation in cancer in children. Methods and Materials: Craniospinal irradiation (CSI) using three-dimensional conformal radiotherapy (3D-CRT), tomotherapy (TOMO), and proton beam treatment (PBT) in the scattering mode was planned for each of 10 patients at our institution. Dosimetric benefits and organ-specific radiation-induced cancer risks were based on comparisons of dose-volume histograms (DVHs) and on the application of organ equivalent doses (OEDs), respectively. Results: When we analyzed the organ-at-risk volumes that received 30%, 60%, and 90% of the prescribed dose (PD), we found that PBT was superior to TOMO and 3D-CRT. On average, the doses delivered by PBT to the esophagus, stomach, liver, lung, pancreas, and kidney were 19.4 Gy, 0.6 Gy, 0.3 Gy, 2.5 Gy, 0.2 Gy, and 2.2 Gy for the PD of 36 Gy, respectively, which were significantly lower than the doses delivered by TOMO (22.9 Gy, 4.5 Gy, 6.1 Gy, 4.0 Gy, 13.3 Gy, and 4.9 Gy, respectively) and 3D-CRT (34.6 Gy, 3.6 Gy, 8.0 Gy, 4.6 Gy, 22.9 Gy, and 4.3 Gy, respectively). Although the average doses delivered by PBT to the chest and abdomen were significantly lower than those of 3D-CRT or TOMO, these differences were reduced in the head-and-neck region. OED calculations showed that the risk of secondary cancers in organs such as the stomach, lungs, thyroid, and pancreas was much higher when 3D-CRT or TOMO was used than when PBT was used. Conclusions: Compared with photon techniques, PBT showed improvements in most dosimetric parameters for CSI patients, with lower OEDs to organs at risk.

  8. Dose-rate conversion factors for external exposure to photons and electrons

    SciTech Connect

    Kocher, D. C.

    1980-01-01

    This paper describes recent modifications of the computer code DOSFACTER, which was developed for the purpose of estimating dose-rate conversion factors for external exposure to photons and electrons emitted by radionuclides dispersed in the environment. The modifications and additions which have been made to the calculations outlined above include the following: (1) calculation of electron dose-rate factors for radiosensitive portions of the skin; (2) incorporation of improved estimates of organ dose-rate factors for photons; and (3) calculation of dose-rate factors for additional radio nuclides and incorporation of updated radioactive decay data for all radionuclides. The revised dose-rate factors described in this paper are available upon request from the Radiation Shielding Information Center at Oak Ridge National Laboratory.

  9. Reproducibility of the external surface position in left-breast DIBH radiotherapy with spirometer-based monitoring.

    PubMed

    Fassi, Aurora; Ivaldi, Giovanni B; Meaglia, Ilaria; Porcu, Patrizia; Tabarelli de Fatis, Paola; Liotta, Marco; Riboldi, Marco; Baroni, Guido

    2014-01-01

    Deep inspiration breath hold (DIBH) in left-sided breast cancer radiotherapy treatments allows for a reduction in cardiac and pulmonary doses without compromising target coverage. The selection of the most appropriate technology for DIBH monitoring is a crucial issue. We evaluated the stability and reproducibility of DIBHs controlled by a spirometric device, by assessing the variability of the external surface position within a single DIBH (intra-DIBH) and between DIBHs performed in the same treatment session (intrafraction) or in different sessions (interfraction). The study included seven left-breast cancer patients treated with spirometer-based DIBH radiotherapy. Infrared optical tracking was used to record the 3D coordinates of seven to eleven passive markers placed on the patient's thoraco-abdominal surface during 29-43 DIBHs performed in six to eight treatment sessions. The obtained results showed displacements of the external surface between different sessions up to 6.3mm along a single direction, even at constant inspired volumes. The median value of the interfraction variability in the position of breast passive markers was 2.9 mm (range 1.9-4.8 mm) in the latero-lateral direction, 3.6 mm (range 2.2-4.6mm) in the antero-posterior direction, and 4.3mm (range 2.8-6.2 mm) in the cranio-caudal direction. There were no significant dose distribution variations for target and organs at risk with respect to the treatment plan, confirming the adequacy of the applied clinical margins (15 mm) to compensate for the measured setup uncertainties. This study demonstrates that spirometer-based control does not guarantee a stable and reproducible position of the external surface in left-breast DIBH radiotherapy, suggesting the need for more robust DIBH monitoring techniques when reduced margins and setup uncertainties are required for improving normal tissue sparing and decreasing cardiac and pulmonary toxicity. PMID:24423845

  10. SU-E-T-234: Modulated Photon Radiotherapy (XMRT):The Impact of Incorporating Energy Modulation Into Intensity Modulated Radiotherapy (IMRT) Optimization

    SciTech Connect

    McGeachy, P; Khan, R

    2014-06-01

    Purpose: To develop a new radiotherapy plan optimization technique that, for a given organ geometry, will find the optimal photon beam energies and fluences to produce a desirable dose distribution. This new modulated (both in energy and fluence) photon radiotherapy (XMRT) was compared with intensity modulated radiotherapy (IMRT) for a simple organ geometry. Methods: The XMRT optimization was formulated using a linear programming approach where the objective function is the mean dose to the healthy organs and dose-point constraints were assigned to each organ of interest. The organ geometry consisted of a target, two organs at risk (OARs), and normal tissue. A seven-equispaced-coplanar beam arrangement was used. For conventional IMRT, only 6 MV beams were available, while XMRT was optimized using 6 and 18 MV beams. A prescribed dose (PD) of 72 GY was assigned to the target, with upper and lower bounds of 110% and 95% of the PD, respectively. Both OARs were assigned a maximum dose of 64 Gy, while the normal tissue was assigned a maximum dose of 66 Gy. A numerical solver, Gurobi, generated solutions for the XMRT and IMRT problems. The dose-volume histograms from IMRT and XMRT solutions were compared. Results: The maximum, minimum, mean, and homogeneity of the dose to the target were comparable between IMRT and XMRT. Though IMRT had improved dose conformity relative to XMRT, XMRT reduced the mean dose to both OARs by more than 1 Gy. For normal tissue, an increase of 5 Gy in mean dose and 27 percent in integral dose was seen for IMRT relative to XMRT. Conclusion: This work demonstrates the benefits of simultaneously modulating photon beam energy and fluence using our XMRT approach in a given phantom geometry. While target coverage was comparable, dose to healthy structures was reduced using XMRT.

  11. Wavelength-controlled external-cavity laser with a silicon photonic crystal resonant reflector

    NASA Astrophysics Data System (ADS)

    Gonzalez-Fernandez, A. A.; Liles, Alexandros A.; Persheyev, Saydulla; Debnath, Kapil; O'Faolain, Liam

    2016-03-01

    We report the experimental demonstration of an alternative design of external-cavity hybrid lasers consisting of a III-V Semiconductor Optical Amplifier with fiber reflector and a Photonic Crystal (PhC) based resonant reflector on SOI. The Silicon reflector comprises a polymer (SU8) bus waveguide vertically coupled to a PhC cavity and provides a wavelength-selective optical feedback to the laser cavity. This device exhibits milliwatt-level output power and sidemode suppression ratio of more than 25 dB.

  12. Practical and fast quantum random number generation based on photon arrival time relative to external reference

    SciTech Connect

    Nie, You-Qi; Zhang, Jun Pan, Jian-Wei; Zhang, Hong-Fei; Wang, Jian; Zhang, Zhen; Ma, Xiongfeng

    2014-02-03

    We present a practical high-speed quantum random number generator, where the timing of single-photon detection relative to an external time reference is measured as the raw data. The bias of the raw data can be substantially reduced compared with the previous realizations. The raw random bit rate of our generator can reach 109 Mbps. We develop a model for the generator and evaluate the min-entropy of the raw data. Toeplitz matrix hashing is applied for randomness extraction, after which the final random bits are able to pass the standard randomness tests.

  13. Monte Carlo calculation based on hydrogen composition of the tissue for MV photon radiotherapy.

    PubMed

    Demol, Benjamin; Viard, Romain; Reynaert, Nick

    2015-01-01

    The purpose of this study was to demonstrate that Monte Carlo treatment planning systems require tissue characterization (density and composition) as a function of CT number. A discrete set of tissue classes with a specific composition is introduced. In the current work we demonstrate that, for megavoltage photon radiotherapy, only the hydrogen content of the different tissues is of interest. This conclusion might have an impact on MRI-based dose calculations and on MVCT calibration using tissue substitutes. A stoichiometric calibration was performed, grouping tissues with similar atomic composition into 15 dosimetrically equivalent subsets. To demonstrate the importance of hydrogen, a new scheme was derived, with correct hydrogen content, complemented by oxygen (all elements differing from hydrogen are replaced by oxygen). Mass attenuation coefficients and mass stopping powers for this scheme were calculated and compared to the original scheme. Twenty-five CyberKnife treatment plans were recalculated by an in-house developed Monte Carlo system using tissue density and hydrogen content derived from the CT images. The results were compared to Monte Carlo simulations using the original stoichiometric calibration. Between 300 keV and 3 MeV, the relative difference of mass attenuation coefficients is under 1% within all subsets. Between 10 keV and 20 MeV, the relative difference of mass stopping powers goes up to 5% in hard bone and remains below 2% for all other tissue subsets. Dose-volume histograms (DVHs) of the treatment plans present no visual difference between the two schemes. Relative differences of dose indexes D98, D95, D50, D05, D02, and Dmean were analyzed and a distribution centered around zero and of standard deviation below 2% (3 σ) was established. On the other hand, once the hydrogen content is slightly modified, important dose differences are obtained. Monte Carlo dose planning in the field of megavoltage photon radiotherapy is fully achievable using

  14. Monte Carlo based beam model using a photon MLC for modulated electron radiotherapy

    SciTech Connect

    Henzen, D. Manser, P.; Frei, D.; Volken, W.; Born, E. J.; Vetterli, D.; Chatelain, C.; Fix, M. K.; Neuenschwander, H.; Stampanoni, M. F. M.

    2014-02-15

    Purpose: Modulated electron radiotherapy (MERT) promises sparing of organs at risk for certain tumor sites. Any implementation of MERT treatment planning requires an accurate beam model. The aim of this work is the development of a beam model which reconstructs electron fields shaped using the Millennium photon multileaf collimator (MLC) (Varian Medical Systems, Inc., Palo Alto, CA) for a Varian linear accelerator (linac). Methods: This beam model is divided into an analytical part (two photon and two electron sources) and a Monte Carlo (MC) transport through the MLC. For dose calculation purposes the beam model has been coupled with a macro MC dose calculation algorithm. The commissioning process requires a set of measurements and precalculated MC input. The beam model has been commissioned at a source to surface distance of 70 cm for a Clinac 23EX (Varian Medical Systems, Inc., Palo Alto, CA) and a TrueBeam linac (Varian Medical Systems, Inc., Palo Alto, CA). For validation purposes, measured and calculated depth dose curves and dose profiles are compared for four different MLC shaped electron fields and all available energies. Furthermore, a measured two-dimensional dose distribution for patched segments consisting of three 18 MeV segments, three 12 MeV segments, and a 9 MeV segment is compared with corresponding dose calculations. Finally, measured and calculated two-dimensional dose distributions are compared for a circular segment encompassed with a C-shaped segment. Results: For 15 × 34, 5 × 5, and 2 × 2 cm{sup 2} fields differences between water phantom measurements and calculations using the beam model coupled with the macro MC dose calculation algorithm are generally within 2% of the maximal dose value or 2 mm distance to agreement (DTA) for all electron beam energies. For a more complex MLC pattern, differences between measurements and calculations are generally within 3% of the maximal dose value or 3 mm DTA for all electron beam energies. For the

  15. Out-of-field neutron and leakage photon exposures and the associated risk of second cancers in high-energy photon radiotherapy: current status.

    PubMed

    Takam, R; Bezak, E; Marcu, L G; Yeoh, E

    2011-10-01

    Determination and understanding of out-of-field neutron and photon doses in accelerator-based radiotherapy is an important issue since linear accelerators operating at high energies (>10 MV) produce secondary radiations that irradiate parts of the patient's anatomy distal to the target region, potentially resulting in detrimental health effects. This paper provides a compilation of data (technical and clinical) reported in the literature on the measurement and Monte Carlo simulations of peripheral neutron and photon doses produced from high-energy medical linear accelerators and the reported risk and/or incidence of second primary cancer of tissues distal to the target volume. Information in the tables facilitates easier identification of (1) the various methods and measurement techniques used to determine the out-of-field neutron and photon radiations, (2) reported linac-dependent out-of-field doses, and (3) the risk/incidence of second cancers after radiotherapy due to classic and modern treatment methods. Regardless of the measurement technique and type of accelerator, the neutron dose equivalent per unit photon dose ranges from as low as 0.1 mSv/Gy to as high as 20.4 mSv/Gy. This radiation dose potentially contributes to the induction of second primary cancer in normal tissues outside the treated area. PMID:21756083

  16. Single Photon Scattering Properties in Coupled-Resonator Waveguide Coupling with a Nanocavity Interacting with an External Mirror

    NASA Astrophysics Data System (ADS)

    Mu-Tian, Cheng; Wei-Wei, Zong; Gen-Long, Ye; Xiao-San, Ma; Jia-Yan, Zhang; Bing, Wang

    2016-06-01

    We investigate theoretically single photon transport properties in coupled-resonator waveguide coupling with a nanocavity interacting with an external mirror. By using the discrete coordinates approach, transmission and reflection amplitudes of the propagating single photon in the waveguide are obtained. The influence of the coupling strength between the nanocavity and the external mirror on the single photon scattering spectra is discussed. We also extend the results to the waveguide with linear and quadratic form dispersion relations. Supported by the National Natural Science Foundation of China under Grant Nos. 11105001 and 61472282, the Anhui Provincial Natural Science Foundation under Grant Nos. 1408085QA22, 1608085MA09, and 1508085MF129.

  17. A Dosimetric Comparison of Proton and Intensity-Modulated Photon Radiotherapy for Pediatric Parameningeal Rhabdomyosarcomas

    SciTech Connect

    Kozak, Kevin R.; Adams, Judith; Krejcarek, Stephanie J.; Tarbell, Nancy J.; Yock, Torunn I.

    2009-05-01

    Purpose: We compared tumor and normal tissue dosimetry of proton radiation therapy with intensity-modulated radiation therapy (IMRT) for pediatric parameningeal rhabdomyosarcomas (PRMS). Methods and Materials: To quantify dosimetric differences between contemporary proton and photon treatment for pediatric PRMS, proton beam plans were compared with IMRT plans. Ten patients treated with proton radiation therapy at Massachusetts General Hospital had IMRT plans generated. To facilitate dosimetric comparisons, clinical target volumes and normal tissue volumes were held constant. Plans were optimized for target volume coverage and normal tissue sparing. Results: Proton and IMRT plans provided acceptable and comparable target volume coverage, with at least 99% of the CTV receiving 95% of the prescribed dose in all cases. Improved dose conformality provided by proton therapy resulted in significant sparing of all examined normal tissues except for ipsilateral cochlea and mastoid; ipsilateral parotid gland sparing was of borderline statistical significance (p = 0.05). More profound sparing of contralateral structures by protons resulted in greater dose asymmetry between ipsilateral and contralateral retina, optic nerves, cochlea, and mastoids; dose asymmetry between ipsilateral and contralateral parotids was of borderline statistical significance (p = 0.05). Conclusions: For pediatric PRMS, superior normal tissue sparing is achieved with proton radiation therapy compared with IMRT. Because of enhanced conformality, proton plans also demonstrate greater normal tissue dose distribution asymmetry. Longitudinal studies assessing the impact of proton radiotherapy and IMRT on normal tissue function and growth symmetry are necessary to define the clinical consequences of these differences.

  18. A Phase II study of external-beam radiotherapy and endovascular brachytherapy with PTA and stenting for femoropopliteal artery restenosis

    SciTech Connect

    Narayan, Kailash . E-mail: kailash.narayan@petermac.org; Denton, Michael; Das, Ram; Bernshaw, David; Rolfo, Aldo; Dyk, Sylvia van; Mirakian, Alex

    2006-09-01

    Purpose: To assess the safety and seek evidence of efficacy of combined external-beam radiotherapy (EBRT) and endovascular brachytherapy in the treatment of stenotic vascular lesions. Methods and Materials: Seventeen patients with high risk for restenosis of femoropopliteal arteries were enrolled in this study from February 2000 to August 2002. The external beam radiotherapy regimen consisted of 10 Gy in 5 fractions of 2 Gy, starting on Day 0. This was followed on Day 6 by angiography, stent placement, and intraluminal brachytherapy to a dose of 10 Gy at 1.2 mm from stent surface. The EBRT was continued from the same day to another 10 Gy in 2 Gy daily fractions for 5 days. Results: The follow up ranged from 33 months to 60 months. At the time of analysis 15 of 17 patients were alive with patent stents. Of these, 10 were symptom-free. Two patients died of unrelated causes. Conclusions: The combination of EBRT and endovascular brachytherapy provided adequate dose distribution without any geographical miss or 'candy wrapper' restenosis. No incidence of aneurysmal dilation of radiated vascular segment was observed. The treatment was feasible, well tolerated, and achieved 88% stenosis free survival.

  19. The role of postoperative external-beam radiotherapy in the management of patients with papillary thyroid cancer invading the trachea

    SciTech Connect

    Keum, Ki Chang; Suh, Yang Gun; Koom, Woong Sub; Cho, Jae Ho; Shim, Su Jung; Lee, Chang Geol; Park, Chung Soo; Chung, Woong Youn; Kim, Gwi Eon . E-mail: gekim@yumc.yonsei.ac.kr

    2006-06-01

    Purpose: To determine the role of adjuvant external-beam radiotherapy (EBRT) in the management of patients with well-differentiated thyroid cancer invading the trachea. Methods and Materials: Of 1,098 thyroid cancer patients, 68 (6%) were found to have tracheal invasion, and they all received 'shave' excision of the tracheal cartilage. Among them, 12 patients had no postoperative residuum, 43 patients had microscopic residuum, and 13 patients had macroscopic residuum. All patients were divided into two groups according to treatment modality with or without EBRT; (1) the control group (n = 43) and (2) the EBRT group (n = 25). Results: The locoregional recurrence rate for EBRT patients was much lower than that of control patients (51% for the control group vs. 8% for the EBRT group) (p < 0.01). The 10-year local progression-free survival rate for the EBRT group was significantly better than that of the control group (89% in the EBRT group vs. 38% in the control group) (log-rank, p < 0.01). The use of adjuvant EBRT after conservative surgery was an independent prognostic factor in univariate and multivariate analyses. Conclusions: External-beam radiotherapy was found to be effective, particularly in patients with thyroid cancer invading the trachea with microscopic or gross residuum after conservative surgery.

  20. Down-staging of hepatocellular carcinoma via external-beam radiotherapy with subsequent liver transplantation: a case report.

    PubMed

    Wigg, Alan; Hon, Kenneth; Mosel, Leigh; Sladden, Nicole; Palumbo, Kevin

    2013-10-01

    Despite the widespread use of locoregional therapies [radiofrequency ablation and transarterial chemoembolization (TACE)], there is currently a lack of high-quality evidence supporting their use for hepatocellular carcinoma (HCC) in patients on the liver transplantation (LT) waiting list or requiring down-staging. Radiotherapy has rarely been used in this setting and has usually been in the form of more complex and less accessible techniques such as proton-beam and stereotactic body radiation therapy. Only 1 report describes the use of conventional 3-dimensional conformal external-beam radiotherapy (cEBRT) techniques as neoadjuvant or down-staging therapy for patients who are LT candidates. This report describes the use of cEBRT in a 52-year-old hepatitis C-positive man with cirrhosis. A 40-mm right lobe HCC was treated initially with TACE while he was on the waiting list. The lesion progressed beyond transplant criteria (76 mm). Conventional external-beam radiotherapy (EBRT) was used (54 Gy in 27 fractions) to down-stage the lesion. EBRT was well tolerated and resulted in a complete radiological response with no arterial enhancement of the lesion for a total of 16 months. Subsequent LT and a review of the explant demonstrated complete histological necrosis of the lesion. This report provides the first description of complete histological necrosis of HCC through the use of cEBRT techniques as down-staging/neoadjuvant therapy before LT. Because of its potential efficacy, accessibility, tolerability, noninvasive and outpatient nature, and ability to treat lesions adjacent to vessels and biliary structures, further trials examining the efficacy of cEBRT versus other neoadjuvant techniques are urgently required. PMID:23894122

  1. Organ dose conversion coefficients for external photon irradiation using the Chinese voxel phantom (CVP).

    PubMed

    Li, Junli; Qiu, Rui; Zhang, Zhan; Liu, Liye; Zeng, Zhi; Bi, Lei; Li, Wenqian

    2009-07-01

    A set of conversion coefficients from kerma free-in-air to the organ absorbed dose are presented for external monoenergetic photon beams from 10 keV to 10 MeV based on a whole-body, Chinese adult male voxel phantom. This computational phantom, called the Chinese voxel phantom (CVP), including totally 23 organs, was developed from magnetic resonance imaging of a young healthy Chinese man at a resolution of 2 x 2 mm. Compared with the ICRP Reference Man, more than half of the organs or tissues in the CVP show mass differences of more than 20. Monte Carlo simulations with MCNP code were carried out to calculate the organ dose conversion coefficients. Irradiation conditions include anterior-posterior, posterior-anterior (PA), right-lateral, left-lateral, rotational and isotropic geometries. Organ dose conversion coefficients from this study are compared with the data from the Asian voxel phantoms Visible Chinese Human and KORMAN. These data sets agree with each other within 10% for photon energy >5 MeV. However, discrepancies of 34-63% were observed for organs of the alimentary tract, such as the oesophagus and stomach, those of the urinary system, such as the bladder wall and thyroid, especially at low photon energy range and PA geometry. These results suggest that the anatomical variation within the Chinese population, as represented by these adult male voxel phantoms, can lead to uncertainties when a standard phantom is used for the entire population. PMID:19457976

  2. SU-E-T-43: Analytical Model for Photon Peripheral Dose in Radiotherapy Treatments

    SciTech Connect

    Nieto, B Sanchez; El far, R; Romero-Exposito, M; Lagares, J; Mateo, JC; Terron, JA; Irazola, L; Sanchez-Doblado, F

    2014-06-01

    Purpose: The higher survival rate of radiotherapy patients entails a growing concern on second cancers associated to peripheral doses. Currently, dosimetry of out-of field doses is still under development. Our group has developed a methodology to estimate neutron equivalent dose in organs (1,2). We aimed to propose a model to estimate out-of-field photon doses in isocentric treatments from basic clinical data. Methods: The proposed function models the dose as the sum of leakage and scatter terms. The latter is modeled as a virtual source at the collimator, which suffers from attenuation in air and tissue, corrected by the inverse-square-law. The model was parameterized using experimental measurements with TLD700 chips placed inside an anthropomorphic phantom (6–18MV) irradiated with conformal and modulated techniques in Elekta, Siemens and Varian linacs. This model provides photon dose at a point as a function of clinical parameters as prescription dose/UM, PTV volume, distance to the field edge, height of the MLC leaves and distance from the the MLC to the isocenter. Model was tested against independent measurements (TLD100) for a VMAT treatment on a Elekta. Dose to organs is modeled from dose to points along the head-to-feet axis of the organ of a “standard man” escalated by patient height. Results: Our semi-empirical model depends on 3 given parameters (leakage parameter can be individualized). A novelty of our model, over other models (e.g., PERIDOSE), arises from its applicability to any technique (independently of the number of MU needed to deliver a dose). Differences between predictions and measurements were < 0.005mSv/UM. Conclusion: We have proposed a unique model which successfully account for photon peripheral organ dose. This model can be applied in the day-to-day clinic as it only needs a few basic parameters which are readily accessible.1. Radiother. Oncol. 107:234–243, 2013. 2. Phys. Med. Biol. 57:6167–6191, 2012.

  3. Reconstruction of Organ Dose for External Radiotherapy Patients in Retrospective Epidemiologic Studies

    PubMed Central

    Lee, Choonik; Jung, Jae Won; Pelletier, Christopher; Pyakuryal, Anil; Lamart, Stephanie; Kim, Jongoh; Lee, Choonsik

    2015-01-01

    Organ dose estimation for retrospective epidemiological studies of late effects in radiotherapy patients involves two challenges: radiological images to represent patient anatomy are not usually available for patient cohorts who were treated years ago, and efficient dose reconstruction methods for large-scale patient cohorts are not well established. In the current study, we developed methods to reconstruct organ doses for radiotherapy patients by using a series of computational human phantoms coupled with a commercial treatment planning system (TPS) and a radiotherapy-dedicated Monte Carlo transport code, and performed illustrative dose calculations. First, we developed methods to convert the anatomy and organ contours of the pediatric and adult hybrid computational phantom series to Digital Imaging and Communications in Medicine (DICOM)-image and DICOM-structure files, respectively. The resulting DICOM files were imported to a commercial TPS for simulating radiotherapy and dose calculation for in-field organs. The conversion process was validated by comparing electron densities relative to water and organ volumes between the hybrid phantoms and the DICOM files imported in TPS, which showed agreements within 0.1% and 2%, respectively. Second, we developed a procedure to transfer DICOM-RT files generated from the Eclipse system directly to a Monte Carlo transport code, X-ray Voxel Monte Carlo (XVMC) for more accurate dose calculations. Third, to illustrate the performance of the established methods, we simulated a whole brain treatment for the 10-year-old male phantom and a prostate treatment for the adult male phantom. Radiation doses to selected organs were calculated using the Eclipse and XVMC, and compared to each other. Organ average doses from the two methods matched within 7%, whereas maximum and minimum point doses differed up to 45%. The dosimetry methods and procedures established in this study will be useful for the reconstruction of organ dose to

  4. Reconstruction of organ dose for external radiotherapy patients in retrospective epidemiologic studies.

    PubMed

    Lee, Choonik; Jung, Jae Won; Pelletier, Christopher; Pyakuryal, Anil; Lamart, Stephanie; Kim, Jong Oh; Lee, Choonsik

    2015-03-21

    Organ dose estimation for retrospective epidemiological studies of late effects in radiotherapy patients involves two challenges: radiological images to represent patient anatomy are not usually available for patient cohorts who were treated years ago, and efficient dose reconstruction methods for large-scale patient cohorts are not well established. In the current study, we developed methods to reconstruct organ doses for radiotherapy patients by using a series of computational human phantoms coupled with a commercial treatment planning system (TPS) and a radiotherapy-dedicated Monte Carlo transport code, and performed illustrative dose calculations. First, we developed methods to convert the anatomy and organ contours of the pediatric and adult hybrid computational phantom series to Digital Imaging and Communications in Medicine (DICOM)-image and DICOM-structure files, respectively. The resulting DICOM files were imported to a commercial TPS for simulating radiotherapy and dose calculation for in-field organs. The conversion process was validated by comparing electron densities relative to water and organ volumes between the hybrid phantoms and the DICOM files imported in TPS, which showed agreements within 0.1 and 2%, respectively. Second, we developed a procedure to transfer DICOM-RT files generated from the TPS directly to a Monte Carlo transport code, x-ray Voxel Monte Carlo (XVMC) for more accurate dose calculations. Third, to illustrate the performance of the established methods, we simulated a whole brain treatment for the 10 year-old male phantom and a prostate treatment for the adult male phantom. Radiation doses to selected organs were calculated using the TPS and XVMC, and compared to each other. Organ average doses from the two methods matched within 7%, whereas maximum and minimum point doses differed up to 45%. The dosimetry methods and procedures established in this study will be useful for the reconstruction of organ dose to support

  5. Reconstruction of organ dose for external radiotherapy patients in retrospective epidemiologic studies

    NASA Astrophysics Data System (ADS)

    Lee, Choonik; Jung, Jae Won; Pelletier, Christopher; Pyakuryal, Anil; Lamart, Stephanie; Kim, Jong Oh; Lee, Choonsik

    2015-03-01

    Organ dose estimation for retrospective epidemiological studies of late effects in radiotherapy patients involves two challenges: radiological images to represent patient anatomy are not usually available for patient cohorts who were treated years ago, and efficient dose reconstruction methods for large-scale patient cohorts are not well established. In the current study, we developed methods to reconstruct organ doses for radiotherapy patients by using a series of computational human phantoms coupled with a commercial treatment planning system (TPS) and a radiotherapy-dedicated Monte Carlo transport code, and performed illustrative dose calculations. First, we developed methods to convert the anatomy and organ contours of the pediatric and adult hybrid computational phantom series to Digital Imaging and Communications in Medicine (DICOM)-image and DICOM-structure files, respectively. The resulting DICOM files were imported to a commercial TPS for simulating radiotherapy and dose calculation for in-field organs. The conversion process was validated by comparing electron densities relative to water and organ volumes between the hybrid phantoms and the DICOM files imported in TPS, which showed agreements within 0.1 and 2%, respectively. Second, we developed a procedure to transfer DICOM-RT files generated from the TPS directly to a Monte Carlo transport code, x-ray Voxel Monte Carlo (XVMC) for more accurate dose calculations. Third, to illustrate the performance of the established methods, we simulated a whole brain treatment for the 10 year-old male phantom and a prostate treatment for the adult male phantom. Radiation doses to selected organs were calculated using the TPS and XVMC, and compared to each other. Organ average doses from the two methods matched within 7%, whereas maximum and minimum point doses differed up to 45%. The dosimetry methods and procedures established in this study will be useful for the reconstruction of organ dose to support

  6. Photonic Crystals with a Reversibly Inducible and Erasable Defect State Using External Stimuli.

    PubMed

    Chen, Mao; Zhang, Yapeng; Jia, Siyu; Zhou, Lin; Guan, Ying; Zhang, Yongjun

    2015-08-01

    The controlled introduction of artificial extrinsic defects is critical to achieve the functions of photonic crystals. Smart defects capable of responding to external stimuli lead to more advanced applications. Here we report a microgel colloidal crystal with a defect state which could be induced and erased reversibly by external stimuli. The crystal was assembled from PNIPAM microgel and P(NIPAM-AAc) microgel of the same size. The resulting doped crystal does not exhibit a defect state in its stop band because of the similar optical properties of the dopant and the host. By increasing the pH value, however, the dopant P(NIPAM-AAc) spheres swell to a larger size and turn into real defects in the crystal, resulting in the appearance of defect state. Adjusting the pH value back restores the size of the dopant spheres, and thus erases the defect state. Temperature, a second external stimulus, could also be used to induce and erase defect states of the crystal. PMID:26102095

  7. Effect of beam arrangement on oral cavity dose in external beam radiotherapy of nasopharyngeal carcinoma

    SciTech Connect

    Wu, Vincent W.C.; Yang Zhining; Zhang Wuzhe; Wu Lili; Lin Zhixiong

    2012-07-01

    This study compared the oral cavity dose between the routine 7-beam intensity-modulated radiotherapy (IMRT) beam arrangement and 2 other 7-beam IMRT with the conventional radiotherapy beam arrangements in the treatment of nasopharyngeal carcinoma (NPC). Ten NPC patients treated by the 7-beam routine IMRT technique (IMRT-7R) between April 2009 and June 2009 were recruited. Using the same computed tomography data, target information, and dose constraints for all the contoured structures, 2 IMRT plans with alternative beam arrangements (IMRT-7M and IMRT-7P) by avoiding the anterior facial beam and 1 conventional radiotherapy plan (CONRT) were computed using the Pinnacle treatment planning system. Dose-volume histograms were generated for the planning target volumes (PTVs) and oral cavity from which the dose parameters and the conformity index of the PTV were recorded for dosimetric comparisons among the plans with different beam arrangements. The dose distributions to the PTVs were similar among the 3 IMRT beam arrangements, whereas the differences were significant between IMRT-7R and CONRT plans. For the oral cavity dose, the 3 IMRT beam arrangements did not show significant difference. Compared with IMRT-7R, CONRT plan showed a significantly lower mean dose, V30 and V-40, whereas the V-60 was significantly higher. The 2 suggested alternative beam arrangements did not significantly reduce the oral cavity dose. The impact of varying the beam angles in IMRT of NPC did not give noticeable effect on the target and oral cavity. Compared with IMRT, the 2-D conventional radiotherapy irradiated a greater high-dose volume in the oral cavity.

  8. Potential for enhancing external beam radiotherapy for lung cancer using high-Z nanoparticles administered via inhalation.

    PubMed

    Hao, Yao; Altundal, Yucel; Moreau, Michele; Sajo, Erno; Kumar, Rajiv; Ngwa, Wilfred

    2015-09-21

    Nanoparticle-aided radiation therapy is emerging as a promising modality to enhance radiotherapy via the radiosensitizing action of high atomic number (Z) nanoparticles. However, the delivery of sufficiently potent concentrations of such nanoparticles to the tumor remain a challenge. This study investigates the dose enhancement to lung tumors due to high-Z nanoparticles (NPs) administered via inhalation during external beam radiotherapy. Here NPs investigated include: cisplatin nanoparticles (CNPs), carboplatin nanoparticles (CBNPs), and gold nanoparticles (GNPs). Using Monte Carlo-generated megavoltage energy spectra, a previously employed analytic method was used to estimate dose enhancement to lung tumors due to radiation-induced photoelectrons from the NPs administered via inhalation route (IR) in comparison to intravenous (IV) administration. Previous studies have indicated about 5% of FDA-approved cisplatin concentrations reach the lung via IV. Meanwhile recent experimental studies indicate that 3.5-14.6 times higher concentrations of NPs can reach the lung by IR compared to IV. Taking these into account, the dose enhancement factor (DEF) defined as the ratio of the radiotherapy dose with and without nanoparticles was calculated for a range of NPs concentrations and tumor sizes. The DEF for IR was then compared with that for IV. For IR with 3.5 times higher concentrations than IV, and 2 cm diameter tumor, clinically significant DEF values of up to 1.19, 1.26, and 1.51 were obtained for CNPs, CBNPs and GNPs. In comparison values of 1.06, 1.08, and 1.15 were obtained via IV administration. For IR with 14.6 times higher concentrations, even higher DEF values were obtained e.g. 1.81 for CNPs. Results also showed that the DEF increased with increasing field size or decreasing tumor volume, as expected. The results of this work indicate that IR administration of targeted high-Z CNPs/CBNPs/GNPs could enable clinically significant DEF to lung tumors compared to IV

  9. Potential for enhancing external beam radiotherapy for lung cancer using high-Z nanoparticles administered via inhalation

    NASA Astrophysics Data System (ADS)

    Hao, Yao; Altundal, Yucel; Moreau, Michele; Sajo, Erno; Kumar, Rajiv; Ngwa, Wilfred

    2015-09-01

    Nanoparticle-aided radiation therapy is emerging as a promising modality to enhance radiotherapy via the radiosensitizing action of high atomic number (Z) nanoparticles. However, the delivery of sufficiently potent concentrations of such nanoparticles to the tumor remain a challenge. This study investigates the dose enhancement to lung tumors due to high-Z nanoparticles (NPs) administered via inhalation during external beam radiotherapy. Here NPs investigated include: cisplatin nanoparticles (CNPs), carboplatin nanoparticles (CBNPs), and gold nanoparticles (GNPs). Using Monte Carlo-generated megavoltage energy spectra, a previously employed analytic method was used to estimate dose enhancement to lung tumors due to radiation-induced photoelectrons from the NPs administered via inhalation route (IR) in comparison to intravenous (IV) administration. Previous studies have indicated about 5% of FDA-approved cisplatin concentrations reach the lung via IV. Meanwhile recent experimental studies indicate that 3.5-14.6 times higher concentrations of NPs can reach the lung by IR compared to IV. Taking these into account, the dose enhancement factor (DEF) defined as the ratio of the radiotherapy dose with and without nanoparticles was calculated for a range of NPs concentrations and tumor sizes. The DEF for IR was then compared with that for IV. For IR with 3.5 times higher concentrations than IV, and 2 cm diameter tumor, clinically significant DEF values of up to 1.19, 1.26, and 1.51 were obtained for CNPs, CBNPs and GNPs. In comparison values of 1.06, 1.08, and 1.15 were obtained via IV administration. For IR with 14.6 times higher concentrations, even higher DEF values were obtained e.g. 1.81 for CNPs. Results also showed that the DEF increased with increasing field size or decreasing tumor volume, as expected. The results of this work indicate that IR administration of targeted high-Z CNPs/CBNPs/GNPs could enable clinically significant DEF to lung tumors compared to IV

  10. Potential for enhancing external beam radiotherapy for lung cancer using high-Z nanoparticles administered via inhalation

    PubMed Central

    Hao, Yao; Altundal, Yucel; Moreau, Michele; Sajo, Erno; Kumar, Rajiv; Ngwa, Wilfred

    2016-01-01

    Nanoparticle-aided radiation therapy is emerging as a promising modality to enhance radiotherapy via the radiosensitizing action of high atomic number (Z) nanoparticles. However, the delivery of sufficiently potent concentrations of such nanoparticles to the tumor remain a challenge. This study investigates the dose enhancement to lung tumors due to high-Z nanoparticles (NPs) administered via inhalation during external beam radiotherapy. Here NPs investigated include: cisplatin nanoparticles (CNPs), carboplatin nanoparticles (CBNPs), and gold nanoparticles (GNPs). Using Monte Carlo–generated megavoltage energy spectra, a previously employed analytic method was used to estimate dose enhancement to lung tumors due to radiation-induced photoelectrons from the NPs administered via inhalation route (IR) in comparison to intravenous (IV) administration. Previous studies have indicated about 5% of FDA-approved cisplatin concentrations reach the lung via IV. Meanwhile recent experimental studies indicate that 3.5–14.6 times higher concentrations of NPs can reach the lung by IR compared to IV. Taking these into account, the dose enhancement factor (DEF) defined as the ratio of the radiotherapy dose with and without nanoparticles was calculated for a range of NPs concentrations and tumor sizes. The DEF for IR was then compared with that for IV. For IR with 3.5 times higher concentrations than IV, and 2 cm diameter tumor, clinically significant DEF values of up to 1.19, 1.26, and 1.51 were obtained for CNPs, CBNPs and GNPs. In comparison values of 1.06, 1.08, and 1.15 were obtained via IV administration. For IR with 14.6 times higher concentrations, even higher DEF values were obtained e.g. 1.81 for CNPs. Results also showed that the DEF increased with increasing field size or decreasing tumor volume, as expected. The results of this work indicate that IR administration of targeted high-Z CNPs/CBNPs/GNPs could enable clinically significant DEF to lung tumors compared to

  11. External Beam Radiotherapy for Clinically Localized Hormone-Refractory Prostate Cancer: Clinical Significance of Nadir Prostate-Specific Antigen Value Within 12 Months

    SciTech Connect

    Ogawa, Kazuhiko Nakamura, Katsumasa; Sasaki, Tomonari; Onishi, Hiroshi; Koizumi, Masahiko; Shioyama, Yoshiyuki; Araya, Masayuki; Mukumoto, Nobutaka M.S.; Mitsumori, Michihide; Teshima, Teruki

    2009-07-01

    Purpose: To analyze retrospectively the results of external beam radiotherapy for clinically localized hormone-refractory prostate cancer and investigate the clinical significance of nadir prostate-specific antigen (PSA) value within 12 months (nPSA12) as an early estimate of clinical outcomes after radiotherapy. Methods and Materials: Eighty-four patients with localized hormone-refractory prostate cancer treated with external beam radiotherapy were retrospectively reviewed. The total radiation doses ranged from 30 to 76 Gy (median, 66 Gy), and the median follow-up period for all 84 patients was 26.9 months (range, 2.7-77.3 months). Results: The 3-year actuarial overall survival, progression-free survival (PFS), and local control rates in all 84 patients after radiotherapy were 67%, 61%, and 93%, respectively. Although distant metastases and/or regional lymph node metastases developed in 34 patients (40%) after radiotherapy, local progression was observed in only 5 patients (6%). Of all 84 patients, the median nPSA12 in patients with clinical failure and in patients without clinical failure was 3.1 ng/mL and 0.5 ng/mL, respectively. When dividing patients according to low (<0.5 ng/mL) and high ({>=}0.5 ng/mL) nPSA12 levels, the 3-year PFS rate in patients with low nPSA12 and in those with high nPSA12 was 96% and 44%, respectively (p < 0.0001). In univariate analysis, nPSA12 and pretreatment PSA value had a significant impact on PFS, and in multivariate analysis nPSA12 alone was an independent prognostic factor for PFS after radiotherapy. Conclusions: External beam radiotherapy had an excellent local control rate for clinically localized hormone-refractory prostate cancer, and nPSA12 was predictive of clinical outcomes after radiotherapy.

  12. Real and virtual photons in an external constant electromagnetic field of most general form

    SciTech Connect

    Shabad, Anatoly E.; Usov, Vladimir V.

    2010-06-15

    The photon behavior in an arbitrary superposition of constant magnetic and electric fields is considered on most general grounds based on the first principles like Lorentz, gauge, charge, and parity invariance. We make model-independent and approximation-independent, but still rather informative, statements about the behavior that the requirement of causal propagation prescribes to massive and massless branches of dispersion curves, and describe the way the eigenmodes are polarized. We find, as a consequence of Hermiticity in the transparency domain, that adding a smaller electric field to a strong magnetic field in parallel to the latter causes enhancement of birefringence. We find the magnetic field produced by a point electric charge far from it--a manifestation of magnetoelectric phenomenon. We establish degeneracies of the polarization tensor that--under special kinematical conditions--occur due to space-time symmetries of the vacuum left after the external field is imposed.

  13. Effect of Gold Nanoparticles on Prostate Dose Distribution under Ir-192 Internal and 18 MV External Radiotherapy Procedures Using Gel Dosimetry and Monte Carlo Method

    PubMed Central

    Khosravi, H.; Hashemi, B.; Mahdavi, S. R.; Hejazi, P.

    2015-01-01

    Background Gel polymers are considered as new dosimeters for determining radiotherapy dose distribution in three dimensions. Objective The ability of a new formulation of MAGIC-f polymer gel was assessed by experimental measurement and Monte Carlo (MC) method for studying the effect of gold nanoparticles (GNPs) in prostate dose distributions under the internal Ir-192 and external 18MV radiotherapy practices. Method A Plexiglas phantom was made representing human pelvis. The GNP shaving 15 nm in diameter and 0.1 mM concentration were synthesized using chemical reduction method. Then, a new formulation of MAGIC-f gel was synthesized. The fabricated gel was poured in the tubes located at the prostate (with and without the GNPs) and bladder locations of the phantom. The phantom was irradiated to an Ir-192 source and 18 MV beam of a Varian linac separately based on common radiotherapy procedures used for prostate cancer. After 24 hours, the irradiated gels were read using a Siemens 1.5 Tesla MRI scanner. The absolute doses at the reference points and isodose curves resulted from the experimental measurement of the gels and MC simulations following the internal and external radiotherapy practices were compared. Results The mean absorbed doses measured with the gel in the presence of the GNPs in prostate were 15% and 8 % higher than the corresponding values without the GNPs under the internal and external radiation therapies, respectively. MC simulations also indicated a dose increase of 14 % and 7 % due to presence of the GNPs, for the same experimental internal and external radiotherapy practices, respectively. Conclusion There was a good agreement between the dose enhancement factors (DEFs) estimated with MC simulations and experiment gel measurements due to the GNPs. The results indicated that the polymer gel dosimetry method as developed and used in this study, can be recommended as a reliable method for investigating the DEF of GNPs in internal and external

  14. Investigation of the robustness of adaptive neuro-fuzzy inference system for tracking moving tumors in external radiotherapy.

    PubMed

    Torshabi, Ahmad Esmaili

    2014-12-01

    In external radiotherapy of dynamic targets such as lung and breast cancers, accurate correlation models are utilized to extract real time tumor position by means of external surrogates in correlation with the internal motion of tumors. In this study, a correlation method based on the neuro-fuzzy model is proposed to correlate the input external motion data with internal tumor motion estimation in real-time mode, due to its robustness in motion tracking. An initial test of the performance of this model was reported in our previous studies. In this work by implementing some modifications it is resulted that ANFIS is still robust to track tumor motion more reliably by reducing the motion estimation error remarkably. After configuring new version of our ANFIS model, its performance was retrospectively tested over ten patients treated with Synchrony Cyberknife system. In order to assess the performance of our model, the predicted tumor motion as model output was compared with respect to the state of the art model. Final analyzed results show that our adaptive neuro-fuzzy model can reduce tumor tracking errors more significantly, as compared with ground truth database and even tumor tracking methods presented in our previous works. PMID:25412886

  15. Measurement of skin and target dose in post-mastectomy radiotherapy using 4 and 6 MV photon beams

    PubMed Central

    2013-01-01

    Background For patients with high risk breast cancer and mastectomy, radiotherapy is the treatment of choice to improve survival and local control. Target dose is mainly limited due to skin reactions. The feasibility of using 4 MV beams for chest wall treatment was studied and compared to standard 6 MV bolus radiotherapy. Methods Post-mastectomy IMRT was planned on an Alderson-phantom using 4 and 6 MV photon beams without/with a 0.5 cm thick bolus. Dose was measured using TLDs placed at 8 locations in 1 and 3 mm depth to represent skin and superficial target dose, respectively. Results 4 MV and 6 MV beams with bolus perform equally regarding target coverage. The minimum and mean superficial target dose for the 6 MV and 4 MV were 93.0% and 94.7%, and 93.1% and 94.4%, respectively. Regarding skin dose the 4 MV photon beam was advantageous. The minimum and mean skin dose for the 6 MV and 4 MV was 76.7% and 81.6%, and 69.4% and 72.9%, respectively. The TPS was able to predict dose in the build-up region with a precision of around 5%. Conclusions The use of 4 MV photon beams are a good alternative for treating the thoracic wall without the need to place a bolus on the patient. The main limitation of 4 MV beams is the limited dose rate. PMID:24238366

  16. SU-E-T-577: Commissioning of a Deterministic Algorithm for External Photon Beams

    SciTech Connect

    Zhu, T; Finlay, J; Mesina, C; Liu, H

    2014-06-01

    Purpose: We report commissioning results for a deterministic algorithm for external photon beam treatment planning. A deterministic algorithm solves the radiation transport equations directly using a finite difference method, thus improve the accuracy of dose calculation, particularly under heterogeneous conditions with results similar to that of Monte Carlo (MC) simulation. Methods: Commissioning data for photon energies 6 – 15 MV includes the percentage depth dose (PDD) measured at SSD = 90 cm and output ratio in water (Spc), both normalized to 10 cm depth, for field sizes between 2 and 40 cm and depths between 0 and 40 cm. Off-axis ratio (OAR) for the same set of field sizes was used at 5 depths (dmax, 5, 10, 20, 30 cm). The final model was compared with the commissioning data as well as additional benchmark data. The benchmark data includes dose per MU determined for 17 points for SSD between 80 and 110 cm, depth between 5 and 20 cm, and lateral offset of up to 16.5 cm. Relative comparisons were made in a heterogeneous phantom made of cork and solid water. Results: Compared to the commissioning beam data, the agreement are generally better than 2% with large errors (up to 13%) observed in the buildup regions of the FDD and penumbra regions of the OAR profiles. The overall mean standard deviation is 0.04% when all data are taken into account. Compared to the benchmark data, the agreements are generally better than 2%. Relative comparison in heterogeneous phantom is in general better than 4%. Conclusion: A commercial deterministic algorithm was commissioned for megavoltage photon beams. In a homogeneous medium, the agreement between the algorithm and measurement at the benchmark points is generally better than 2%. The dose accuracy for a deterministic algorithm is better than a convolution algorithm in heterogeneous medium.

  17. Toxicity Profile With a Large Prostate Volume After External Beam Radiotherapy for Localized Prostate Cancer

    SciTech Connect

    Pinkawa, Michael Fischedick, Karin; Asadpour, Branka; Gagel, Bernd; Piroth, Marc D.; Nussen, Sandra; Eble, Michael J.

    2008-01-01

    Purpose: To assess the impact of prostate volume on health-related quality of life (HRQOL) before and at different intervals after radiotherapy for prostate cancer. Methods and Materials: A group of 204 patients was surveyed prospectively before (Time A), at the last day (Time B), 2 months after (Time C), and 16 months (median) after (Time D) radiotherapy, with a validated questionnaire (Expanded Prostate Cancer Index Composite). The group was divided into subgroups with a small (11-43 cm{sup 3}) and a large (44-151 cm{sup 3}) prostate volume. Results: Patients with large prostates presented with lower urinary bother scores (median 79 vs. 89; p = 0.01) before treatment. Urinary function/bother scores for patients with large prostates decreased significantly compared to patients with small prostates due to irritative/obstructive symptoms only at Time B (pain with urination more than once daily in 48% vs. 18%; p < 0.01). Health-related quality of life did not differ significantly between both patient groups at Times C and D. In contrast to a large prostate, a small initial bladder volume (with associated higher dose-volume load) was predictive for lower urinary bother scores both in the acute and late phase; at Time B it predisposed for pollakiuria but not for pain. Patients with neoadjuvant hormonal therapy reached significantly lower HRQOL scores in several domains (affecting only incontinence in the urinary domain), despite a smaller prostate volume (34 cm{sup 3} vs. 47 cm{sup 3}; p < 0.01). Conclusions: Patients with a large prostate volume have a great risk of irritative/obstructive symptoms (particularly dysuria) in the acute radiotherapy phase. These symptoms recover rapidly and do not influence long-term HRQOL.

  18. Evaluation of Organs at Risk’s Dose in External Radiotherapy of Brain Tumors

    PubMed Central

    Nazemi-Gelyan, Hamideh; Hasanzadeh, Hadi; Makhdumi, Yasha; Abdollahi, Sara; Akbari, Fatemeh; Varshoee-Tabrizi, Fatemeh; Almasrou, Hamzeh; Nikoofar, Alireza; Rezaei-Tavirani, Mostafa

    2015-01-01

    Background Radiotherapy plays an important role in the management of most malignant and many benign primary central nervous system (CNS) tumors. Radiotherapy affects both tumor cells and uninvolved normal cells; so, it is important to estimate absorbed dose to organs at risk in this kind of treatment. The aim of this study was to determine the absorbed dose to chiasma, lens, optic nerve, retina, parotid, thyroid and submandibular gland in frontal lobe brain tumors radiotherapy based on treatment planning system (TPS) calculation and direct measurement on the phantom. Methods A head and neck phantom was constructed using natural human bone and combination of paraffin wax and Sodium Chloride (NaCl) as tissue-equivalent material. Six cylinders were made of phantom material which had cavities to insert Thermoluminescent Dosimeters (TLDs) at several depths in order to measure absorbed dose to chiasma, lens, optic nerve, retina, parotid, thyroid and submandibular gland. Three routine conventional plans associated with tumors of this region and a new purposed technique were performed on the phantom and dose distribution and absorbed dose to critical organs were compared using treatment planning system (TPS) calculation and direct measurement on the phantom. Results Absorbed doses were measured with calibrated TLDs and are expressed in centigray (cGy). In all techniques absorbed dose to all organs except the lenses were at their tolerance dose levels and in the new purposed technique, absorbed dose to chiasma was significantly reduced. Conclusion Our findings showed differences in the range of 1-5% in all techniques between TPS calculation and direct measurements for all organs except submandibular glands and thyroid. Because submandibular glands and thyroid are far from primary radiation field, TLD reading in these regions although small but differs from TPS calculation which shows very smaller doses. This might be due to scattered radiation which is not well considered

  19. Photochemical Internalization of Bleomycin Before External-Beam Radiotherapy Improves Locoregional Control in a Human Sarcoma Model

    SciTech Connect

    Norum, Ole-Jacob; Bruland, Oyvind Sverre; Gorunova, Ludmila; Berg, Kristian

    2009-11-01

    Purpose: The aim of this study was to explore the tumor growth response of the combination photochemical internalization and external-beam radiotherapy. Photochemical internalization is a technology to improve the utilization of therapeutic macromolecules in cancer therapy by photochemical release of endocytosed macromolecules into the cytosol. Methods and Materials: A human sarcoma xenograft TAX-1 was inoculated subcutaneously into nude mice. The photosensitizer AlPcS{sub 2a} and bleomycin were intraperitoneally administrated 48 h and 30 min, respectively, before diode laser light exposure at 670 nm (20 J/cm{sup 2}). Thirty minutes or 7 days after photochemical treatment, the animals were subjected to 4 Gy of ionizing radiation. Results: Using photochemical internalization of bleomycin as an adjunct to ionizing radiation increased the time to progression for the tumors from 17 to 33 days as compared with that observed with photodynamic therapy combined with ionizing radiation as well as for radiochemotherapy with bleomycin. The side effects observed when photochemical internalization of bleomycin was given shortly before ionizing radiation were eliminated by separating the treatment modalities in time. Conclusion: Photochemical internalization of bleomycin combined with ionizing radiation increased the time to progression and showed minimal toxicity and may therefore reduce the total radiation dose necessary to obtain local tumor control while avoiding long-term sequelae from radiotherapy.

  20. External-beam radiotherapy for differentiated thyroid cancer locoregional control: A statement of the American Head and Neck Society

    PubMed Central

    Kiess, Ana P.; Agrawal, Nishant; Brierley, James D.; Duvvuri, Umamaheswar; Ferris, Robert L.; Genden, Eric; Wong, Richard J.; Tuttle, R. Michael; Lee, Nancy Y.; Randolph, Gregory W.

    2016-01-01

    The use of external-beam radiotherapy (EBRT) in differentiated thyroid cancer (DTC) is debated because of a lack of prospective clinical data, but recent retrospective studies have reported benefits in selected patients. The Endocrine Surgery Committee of the American Head and Neck Society provides 4 recommendations regarding EBRT for locoregional control in DTC, based on review of literature and expert opinion of the authors. (1) EBRT is recommended for patients with gross residual or unresectable locoregional disease, except for patients <45 years old with limited gross disease that is radioactive iodine (RAI)-avid. (2) EBRT should not be routinely used as adjuvant therapy after complete resection of gross disease. (3) After complete resection, EBRT may be considered in select patients >45 years old with high likelihood of microscopic residual disease and low likelihood of responding to RAI. (4) Cervical lymph node involvement alone should not be an indication for adjuvant EBRT. PMID:26716601

  1. External-beam radiotherapy for differentiated thyroid cancer locoregional control: A statement of the American Head and Neck Society.

    PubMed

    Kiess, Ana P; Agrawal, Nishant; Brierley, James D; Duvvuri, Umamaheswar; Ferris, Robert L; Genden, Eric; Wong, Richard J; Tuttle, R Michael; Lee, Nancy Y; Randolph, Gregory W

    2016-04-01

    The use of external-beam radiotherapy (EBRT) in differentiated thyroid cancer (DTC) is debated because of a lack of prospective clinical data, but recent retrospective studies have reported benefits in selected patients. The Endocrine Surgery Committee of the American Head and Neck Society provides 4 recommendations regarding EBRT for locoregional control in DTC, based on review of literature and expert opinion of the authors. (1) EBRT is recommended for patients with gross residual or unresectable locoregional disease, except for patients <45 years old with limited gross disease that is radioactive iodine (RAI)-avid. (2) EBRT should not be routinely used as adjuvant therapy after complete resection of gross disease. (3) After complete resection, EBRT may be considered in select patients >45 years old with high likelihood of microscopic residual disease and low likelihood of responding to RAI. (4) Cervical lymph node involvement alone should not be an indication for adjuvant EBRT. PMID:26716601

  2. Results of external review Sandia National Laboratories microelectronics and photonics program (October 2002).

    SciTech Connect

    Peercy, Paul S.; Myers, David R.

    2003-10-01

    The US Department of Energy requires a periodic 'self assessment' of Sandia's Microsystems Program. An external panel review of this program is held approximately every 18 months, and the report from the external review panel serves as the basis for the DOE 'self assessment.' The review for this fiscal year was held on September 30-October 1, 2002 at Sandia National Laboratories, Albuquerque, NM. The panel was comprised of experts in the fields of microelectronics, photonics and microsystems from universities, industry and other Government agencies. A complete list of the panel members is shown as Appendix A to the attached report. The review assesses four areas: relevance to national needs and agency mission; quality of science technology and engineering; performance in the operation of a major facility; and program performance management and planning. Relevance to national needs and agency mission was rated as 'outstanding.' The quality of science, technology, and engineering was rated as 'outstanding.' Operation of a major facility was noted as 'outstanding,' while the category of program performance, management, and planning was rated as 'outstanding.' Sandia's Microsystems Program received an overall rating of 'outstanding' [the highest possible rating]. The attached report was prepared by the panel in a format requested by Sandia to conform with the performance criteria for the DOE self assessment.

  3. Comparative study of membranes induced by PMMA or silicone in rats, and influence of external radiotherapy.

    PubMed

    de Monès, Erwan; Schlaubitz, Silke; Oliveira, Hugo; d'Elbée, Jean-Marie; Bareille, Reine; Bourget, Chantal; Couraud, Lionel; Fricain, Jean-Christophe

    2015-06-01

    The induced membrane technique has been used for long bone defect reconstruction after traumatism. One of the major drawbacks of this method is the difficult removal of the polymethyl methacrylate spacer after membrane formation. We therefore replaced the stiff PMMA spacer with a semi-flexible medical grade silicone spacer. This study aimed to compare subcutaneously formed membranes, induced by PMMA and silicone, in the irradiated or not irradiated areas within 28 rats that received the spacers. Histological analysis was performed to evaluate the composition of the membrane and to quantify the amount of vessels. Histomorphometric measurements were used to evaluate membranes' thickness, while fibrosis and inflammation were scored. The expression of VEGF and BMP-2 in lysates of the crushed membranes was determined by Western blotting. ALP expression was analyzed in HBMSC cultures in contact with the same lysates. Non-irradiated membranes induced by the two spacer types were non-inflammatory, fibrous and organized in layers. Irradiation did not change the macroscopic properties of membranes that were induced by silicone, while PMMA induced membranes were sensitive to the radiotherapy, resulting in thicker, strongly inflammatory membranes. Irradiated membranes showed an overall reduced osteogenic potential. Medical grade silicone is safe for the use in radiotherapy and might therefore be of great advantage for patients in need of cancer treatment. PMID:25770925

  4. Externalities.

    ERIC Educational Resources Information Center

    Zicht, Barbara, Ed.; And Others

    1982-01-01

    This issue explains the concept of externalities (benefits or burdens which accrue to society when there is a difference between the private cost or benefit of an action and the social cost or benefit of that action). These external or social costs of individual actions are often referred to as spillover costs. Three brief teaching units follow…

  5. Quantum correlations and violation of the Bell inequality induced by an external field in a two-photon radiative cascade

    SciTech Connect

    Yuan Luqi; Das, Sumanta

    2011-06-15

    We study the polarization-dependent second-order correlation of a pair of photons emitted in a four-level radiative cascade driven by an external field. It is found that the quantum correlations of the emitted photons, degraded by the energy splitting of the intermediate levels in the radiative cascade, can be efficiently revived by a far-detuned external field. The physics of this revival is linked to an induced Stark shift and the formation of dressed states in the system by the nonresonant external field. Furthermore, we investigated the competition between the effect of the coherent external field and incoherent dephasing of the intermediate levels. We find that the degradation of quantum correlations due to the incoherent dephasing can be contained for small dephasing with the external field. We also studied the nonlocality of the correlations by evaluating the Bell inequality in the linear polarization basis for the radiative cascade. We find that the Bell parameter decreases rapidly with increase in the intermediate-level energy splitting or incoherent dephasing rate to the extent that there is no violation. However, the presence of an external field leads to control over the degrading mechanisms and preservation of nonlocal correlation among the photons. This in turn can induce a violation of Bell's inequality in the radiative cascade for arbitrary intermediate-level splitting and small incoherent dephasing.

  6. Californium-252 Brachytherapy Combined With External-Beam Radiotherapy for Cervical Cancer: Long-Term Treatment Results

    SciTech Connect

    Lei Xin; Qian Chengyuan; Qing Yi; Zhao Kewei; Yang Zhengzhou; Dai Nan; Zhong Zhaoyang; Tang Cheng; Li Zheng; Gu Xianqing; Zhou Qian; Feng Yan; Xiong Yanli; Shan Jinlu; Wang Dong

    2011-12-01

    Purpose: To observe, by retrospective analysis, the curative effects and complications due to californium-252 ({sup 252}Cf) neutron intracavitary brachytherapy (ICBT) combined with external-beam radiotherapy (EBRT) in the treatment of cervical cancer. Methods and Materials: From February 1999 to December 2007, 696 patients with cervical cancer (Stages IB to IIIB) were treated with {sup 252}Cf-ICBT in combination of EBRT. Of all, 31 patients were at Stage IB, 104 at IIA, 363 at IIB, 64 at IIIA, and 134 at IIIB. Californium-252 ICBT was delivered at 7-12 Gy per insertion per week, with a total dose of 29-45 Gy to reference point A in three to five insertions. The whole pelvic cavity was treated with 8-MV X-ray external irradiation at 2 Gy per fraction, four times per week. After 16-38 Gy of external irradiation, the center of the whole pelvic field was blocked with a 4-cm-wide lead shield, with a total external irradiation dose of 44-56 Gy. The total treatment course was 5 to 6 weeks. Results: Overall survival rate at 3 and 5 years for all patients was 76.0% and 64.9%, respectively. Disease-free 3- and 5-year survival rates of patients were 71.2% and 58.4%, respectively. Late complications included vaginal contracture and adhesion, radiation proctitis, radiation cystitis, and inflammatory bowel, which accounted for 5.8%, 7.1%, 6.2%, and 4.9%, respectively. Univariate analysis results showed significant correlation of stage, age, histopathologic grade, and lymph node status with overall survival. Cox multiple regression analysis showed that the independent variables were stage, histopathologic grade, tumor size, and lymphatic metastasis in all patients. Conclusion: Results of this series suggest that the combined use of {sup 252}Cf-ICBT with EBRT is an effective method for treatment of cervical cancer.

  7. Photon trapping in a high-Q cavity by non-resonant atoms coupled with an external broadband vacuum field

    NASA Astrophysics Data System (ADS)

    Basharov, A. M.

    2012-05-01

    A new effect of the decay suppression of photon mode non-resonant to the cavity atoms coupled with an external broadband vacuum field has been described. At a certain number Nacr of cavity atoms, the emission of cavity photons due to the non-resonant interaction with cavity atoms has been stopped by the Stark interaction of cavity atoms with the external broadband vacuum field. In the case of high-Q cavity this provides the effect of radiation trapping. The cavity photon has obtained an additional energy shift. These results have been obtained on the basis of a theory of localized quantum open systems developed with the help of the quantum stochastic differential equation of the generalized Langevin (non-Wiener) type.

  8. Stereotactic Body Radiotherapy as Monotherapy or Post-External Beam Radiotherapy Boost for Prostate Cancer: Technique, Early Toxicity, and PSA Response

    SciTech Connect

    Jabbari, Siavash; Weinberg, Vivian K.; Kaprealian, Tania; Hsu, I-Chow; Ma Lijun; Chuang, Cynthia; Descovich, Martina; Shiao, Stephen; Shinohara, Katsuto; Roach, Mack; Gottschalk, Alexander R.

    2012-01-01

    Purpose: High dose rate (HDR) brachytherapy has been established as an excellent monotherapy or after external-beam radiotherapy (EBRT) boost treatment for prostate cancer (PCa). Recently, dosimetric studies have demonstrated the potential for achieving similar dosimetry with stereotactic body radiotherapy (SBRT) compared with HDR brachytherapy. Here, we report our technique, PSA nadir, and acute and late toxicity with SBRT as monotherapy and post-EBRT boost for PCa using HDR brachytherapy fractionation. Patients and Methods: To date, 38 patients have been treated with SBRT at University of California-San Francisco with a minimum follow-up of 12 months. Twenty of 38 patients were treated with SBRT monotherapy (9.5 Gy Multiplication-Sign 4 fractions), and 18 were treated with SBRT boost (9.5 Gy Multiplication-Sign 2 fractions) post-EBRT and androgen deprivation therapy. PSA nadir to date for 44 HDR brachytherapy boost patients with disease characteristics similar to the SBRT boost cohort was also analyzed as a descriptive comparison. Results: SBRT was well tolerated. With a median follow-up of 18.3 months (range, 12.6-43.5), 42% and 11% of patients had acute Grade 2 gastrourinary and gastrointestinal toxicity, respectively, with no Grade 3 or higher acute toxicity to date. Two patients experienced late Grade 3 GU toxicity. All patients are without evidence of biochemical or clinical progression to date, and favorably low PSA nadirs have been observed with a current median PSA nadir of 0.35 ng/mL (range, <0.01-2.1) for all patients (0.47 ng/mL, range, 0.2-2.1 for the monotherapy cohort; 0.10 ng/mL, range, 0.01-0.5 for the boost cohort). With a median follow-up of 48.6 months (range, 16.4-87.8), the comparable HDR brachytherapy boost cohort has achieved a median PSA nadir of 0.09 ng/mL (range, 0.0-3.3). Conclusions: Early results with SBRT monotherapy and post-EBRT boost for PCa demonstrate acceptable PSA response and minimal toxicity. PSA nadir with SBRT boost

  9. Intraoperative Radiotherapy Versus Whole-Breast External Beam Radiotherapy in Early-Stage Breast Cancer: A Systematic Review and Meta-Analysis.

    PubMed

    Zhang, Li; Zhou, Zhirui; Mei, Xin; Yang, Zhaozhi; Ma, Jinli; Chen, Xingxing; Wang, Junqi; Liu, Guangyu; Yu, Xiaoli; Guo, Xiaomao

    2015-07-01

    There has not been a clear answer about the efficacy of intraoperative radiotherapy (IORT) for women with early-stage breast cancer.The aim of this meta-analysis was to summarize the available evidence comparing the efficacy and safety of IORT with those of whole-breast external beam radiotherapy (EBRT) for women with early-stage breast cancer.MEDLINE, EMBASE, the Web of Science, and the Cochrane Library were searched up to October 2014. Two authors independently conducted the literature selection and data extraction.Studies that compared IORT with whole-breast EBRT were included in the systematic review. IORT was defined as a single dose of irradiation to the tumor bed during breast-conserving surgery rather than whole-breast irradiation.Qualities of RCTs were evaluated according to the PEDro scale. Qualities of non-RCTs were evaluated according to the Methodological Index for Non-Randomized Studies (MINORS). The risk ratios (RRs) of ipsilateral breast tumor recurrence, overall mortality, breast cancer mortality, non-breast cancer mortality, and distant metastasis were pooled using a random-effects model.Four studies with 5415 patients were included in this meta-analysis, including 2 randomized controlled trials (RCTs) and 2 non-RCTs. Ipsilateral breast tumor recurrence was significantly higher in patients with IORT compared to those with whole-breast EBRT (RR 2.83, 95% CI 1.23-6.51), but with significant heterogeneity (I = 58.5%, P = 0.065). Comparing IORT with whole-breast EBRT, the pooled RRs for overall mortality, breast cancer mortality, non-breast cancer mortality, and distant metastasis were 0.88 (95% CI: 0.66-1.17), 1.20 (95% CI: 0.77-1.86), 0.76 (95% CI: 0.44-1.31), and 0.95 (95% CI: 0.61-1.49), respectively.IORT had a significantly higher risk of ipsilateral breast tumor recurrence than whole-breast EBRT. Overall mortality did not differ significantly. IORT should be used in conjunction with the prudent selection of suitable patients. It is

  10. Dose conversion coefficients based on the Chinese mathematical phantom and MCNP code for external photon irradiation.

    PubMed

    Qiu, Rui; Li, Junli; Zhang, Zhan; Liu, Liye; Bi, Lei; Ren, Li

    2009-02-01

    A set of conversion coefficients from kerma free-in-air to the organ-absorbed dose are presented for external monoenergetic photon beams from 10 keV to 10 MeV based on the Chinese mathematical phantom, a whole-body mathematical phantom model. The model was developed based on the methods of the Oak Ridge National Laboratory mathematical phantom series and data from the Chinese Reference Man and the Reference Asian Man. This work is carried out to obtain the conversion coefficients based on this model, which represents the characteristics of the Chinese population, as the anatomical parameters of the Chinese are different from those of Caucasians. Monte Carlo simulation with MCNP code is carried out to calculate the organ dose conversion coefficients. Before the calculation, the effects from the physics model and tally type are investigated, considering both the calculation efficiency and precision. In the calculation irradiation conditions include anterior-posterior, posterior-anterior, right lateral, left lateral, rotational and isotropic geometries. Conversion coefficients from this study are compared with those recommended in the Publication 74 of International Commission on Radiological Protection (ICRP74) since both the sets of data are calculated with mathematical phantoms. Overall, consistency between the two sets of data is observed and the difference for more than 60% of the data is below 10%. However, significant deviations are also found, mainly for the superficial organs (up to 65.9%) and bone surface (up to 66%). The big difference of the dose conversion coefficients for the superficial organs at high photon energy could be ascribed to kerma approximation for the data in ICRP74. Both anatomical variations between races and the calculation method contribute to the difference of the data for bone surface. PMID:19376886

  11. Peripheral dose measurement in high-energy photon radiotherapy with the implementation of MOSFET

    PubMed Central

    Vlachopoulou, Vassiliki; Malatara, Georgia; Delis, Harry; Theodorou, Kiki; Kardamakis, Dimitrios; Panayiotakis, George

    2010-01-01

    AIM: To study the peripheral dose (PD) from high-energy photon beams in radiotherapy using the metal oxide semiconductor field effect transistor (MOSFET) dose verification system. METHODS: The radiation dose absorbed by the MOSFET detector was calculated taking into account the manufacturer’s Correction Factor, the Calibration Factor and the threshold voltage shift. PD measurements were carried out for three different field sizes (5 cm × 5 cm, 10 cm × 10 cm and 15 cm × 15 cm) and for various depths with the source to surface distance set at 100 cm. Dose measurements were realized on the central axis and then at distances (1 to 18 cm) parallel to the edge of the field, and were expressed as the percentage PD (% PD) with respect to the maximum dose (dmax). The accuracy of the results was evaluated with respect to a calibrated 0.3 cm3 ionization chamber. The reproducibility was expressed in terms of standard deviation (s) and coefficient of variation. RESULTS: % PD is higher near the phantom surface and drops to a minimum at the depth of dmax, and then tends to become constant with depth. Internal scatter radiation is the predominant source of PD and the depth dependence is determined by the attenuation of the primary photons. Closer to the field edge, where internal scatter from the phantom dominates, the % PD increases with depth because the ratio of the scatter to primary increases with depth. A few centimeters away from the field, where collimator scatter and leakage dominate, the % PD decreases with depth, due to attenuation by the water. The % PD decreases almost exponentially with the increase of distance from the field edge. The decrease of the % PD is more than 60% and can reach up to 90% as the measurement point departs from the edge of the field. For a given distance, the % PD is significantly higher for larger field sizes, due to the increase of the scattering volume. Finally, the measured PD obtained with MOSFET is higher than that obtained with an

  12. Track-Structure Monte Carlo Modelling in X-ray and Megavoltage Photon Radiotherapy

    NASA Astrophysics Data System (ADS)

    Hugtenburg, Richard P.

    The use of track structure calculations in radiotherapy using conventional low-LET radiation sources is discussed. Microdosimetry and emergent nanodosimetry methods are considered in explaining variations in quality factors associated with clinical practice and in vitro data. Transformation rate in the human derived for the in vitro system CGL1 is presented as a model for the induction of secondary cancer, a late effect associated with radiotherapy treatment.

  13. External-beam radiotherapy as preparative regimen for hepatocyte transplantation after partial hepatectomy

    SciTech Connect

    Christiansen, Hans . E-mail: hchrist@gwdg.de; Koenig, Sarah; Krause, Petra; Hermann, Robert Michael; Rave-Frank, Margret; Proehl, Thomas; Becker, Heinz; Hess, Clemens Friedrich; Schmidberger, Heinz

    2006-06-01

    Purpose: The transplantation of donor hepatocytes is considered a promising option to correct chronic liver failure through repopulation of the diseased organ. This study describes a novel selective external-beam irradiation technique as a preparative regimen for hepatocyte transplantation. Methods and Materials: Livers of dipeptidylpeptidase IV (DPPIV)-deficient rats were preconditioned with external-beam single-dose irradiation (25 Gy) delivered to two thirds of the liver. Four days later, a one-third partial hepatectomy (PH) was performed to resect the untreated liver section, and 15 million wild-type (DPPIV{sup +}) hepatocytes were transplanted via the spleen into the recipient livers. The degree of donor-cell integration and growth was studied 8 h, 3 days, and 5 and 12 weeks after transplantation. Results: Transplanted hepatocytes integrated rapidly into the irradiated liver and proliferated as clusters, finally repopulating the host liver to approximately 20% hepatocyte mass. After 12 weeks, donor cells and their numerous descendents were fully integrated and expressed functional markers to the same extent as host hepatocytes. Conclusions: We demonstrate that external-beam liver irradiation is sufficient to achieve partial repopulation of the host liver after hepatocyte transplantation, under the additional stimulus of one-third PH. The method described has potentially good prospects for its application in a clinically viable form of treatment.

  14. Modeling secondary cancer risk following paediatric radiotherapy: a comparison of intensity modulated proton therapy and photon therapy

    NASA Astrophysics Data System (ADS)

    Shin, Naomi

    Proton radiotherapy is known to reduce the radiation dose delivered to normal healthy tissue compared to photon techniques. The increase in normal tissue sparing could result in fewer acute and late effects from radiation therapy. In this work proton therapy plans were created for patients previously treated using photon therapy. Intensity modulated proton therapy (IMPT) plans were planned using inverse planning in VarianRTM's Eclipse(TM) treatment planning system with a scanning proton beam model to the same relative biological effectiveness (RBE)-weighted prescription dose as the photon plan. Proton and photon plans were compared for target dose conformity and homogeneity, body volumes receiving 2 Gy and 5 Gy, integral dose, dose to normal tissues and second cancer risk. Secondary cancer risk was determined using two methods. The relative risk of secondary cancer was found using the method described by Nguyen et al. 1 by applying a linear relationship between integral dose and relative risk of secondary cancer. The second approach used Schneider et al. 's organ equivalent dose concept to describe the dose in the body and then calculate the excess absolute risk and cumulative risk for solid cancers in the body. IMPT and photon plans had similar target conformity and homogeneity. However IMPT plans had reduced integral dose and volumes of the body receiving low dose. Overall the risk of radiation induced secondary cancer was lower for IMPT plans compared to the corresponding photon plans with a reduction of ~36% using the integral dose model and ˜50% using the organ equivalent dose model. *Please refer to dissertation for footnotes.

  15. Real-Time Study of Prostate Intrafraction Motion During External Beam Radiotherapy With Daily Endorectal Balloon

    SciTech Connect

    Both, Stefan; Wang, Ken Kang-Hsin; Plastaras, John P.; Deville, Curtiland; Bar Ad, Voika; Tochner, Zelig; Vapiwala, Neha

    2011-12-01

    Purpose: To prospectively investigate intrafraction prostate motion during radiofrequency-guided prostate radiotherapy with implanted electromagnetic transponders when daily endorectal balloon (ERB) is used. Methods and Materials: Intrafraction prostate motion from 24 patients in 787 treatment sessions was evaluated based on three-dimensional (3D), lateral, cranial-caudal (CC), and anterior-posterior (AP) displacements. The mean percentage of time with 3D, lateral, CC, and AP prostate displacements >2, 3, 4, 5, 6, 7, 8, 9, and 10 mm in 1 minute intervals was calculated for up to 6 minutes of treatment time. Correlation between the mean percentage time with 3D prostate displacement >3 mm vs. treatment week was investigated. Results: The percentage of time with 3D prostate movement >2, 3, and 4 mm increased with elapsed treatment time (p < 0.05). Prostate movement >5 mm was independent of elapsed treatment time (p = 0.11). The overall mean time with prostate excursions >3 mm was 5%. Directional analysis showed negligible lateral prostate motion; AP and CC motion were comparable. The fraction of time with 3D prostate movement >3 mm did not depend on treatment week of (p > 0.05) over a 4-minute mean treatment time. Conclusions: Daily endorectal balloon consistently stabilizes the prostate, preventing clinically significant displacement (>5 mm). A 3-mm internal margin may sufficiently account for 95% of intrafraction prostate movement for up to 6 minutes of treatment time. Directional analysis suggests that the lateral internal margin could be further reduced to 2 mm.

  16. Investigation of bladder dose and volume factors influencing late urinary toxicity after external beam radiotherapy for prostate cancer

    SciTech Connect

    Cheung, M. Rex . E-mail: mrcheung@mdanderson.org; Tucker, Susan L.; Dong Lei; Crevoisier, Renaud de; Lee, Andrew K.; Frank, Steven; Kudchadker, Rajat J.; Thames, Howard; Mohan, Radhe; Kuban, Deborah

    2007-03-15

    Background: We sought to identify the bladder dose-volume factors associated with an increased risk of late urinary toxicity among prostate cancer patients treated with radiotherapy. Methods and Materials: This retrospective analysis included data from 128 prostate cancer patients treated on protocol with 2 Gy/fraction to 46 Gy followed by a boost to 78 Gy. The endpoint for this analysis was Grade 1 or greater late genitourinary (GU) toxicity occurring within two years of treatment. The Lyman-Kutcher-Burman, mean dose, threshold dose, and hottest volume models were fitted to the toxicity data using the maximum likelihood method. Results: Model fits based on dose-volume histograms tended to fit the toxicity data better than models based on dose-wall histograms. The hottest volume (hotspot) model was found to be the best-fitting model investigated. The best fit was for the hottest 2.9% of bladder (95% CI, 1.1-6.8%). This model has an area under the receiver operating characteristic curve of 0.74. The hotspot model separated the patients into clinically meaningful subgroups with {approx}25% of the patients who received <78 Gy to the hottest 2.9% of bladder had GU toxicity at eight years compared with {approx}50% when the dose was {>=}78 Gy (p = 0.002). Conclusion: This provides the first evidence supporting that bladder 'hotspots' are related to GU toxicity within two years after external beam radiotherapy for prostate cancer. Confirming data are needed from other investigators. Particular attention should be given to hotspots higher than 78 Gy in bladder in radiation treatment planning.

  17. External Beam Radiotherapy for Prostate Cancer: Urinary Outcomes for Men With High International Prostate Symptom Scores (IPSS)

    SciTech Connect

    Malik, Renuka; Jani, Ashesh B.; Liauw, Stanley L.

    2011-07-15

    Purpose: To report the urinary outcome of men treated for prostate cancer with external beam radiotherapy (EBRT) who have pretreatment obstructive urinary symptoms (International Prostate Symptom Score [IPSS] {>=}15). Methods and Materials: We treated 368 patients with EBRT for localized prostate cancer, and pre- and post-radiotherapy (RT) IPSSs were recorded. In total, 80 men had an IPSS {>=}15, 48% of whom were taking genitourinary (GU) medications before RT. The IPSS was followed over time and analyzed as a pretreatment factor against Radiation Therapy Oncology Group acute and late GU toxicity. Results: The median follow-up was 44 months. Among men with a pre-RT IPSS {>=}15, the median IPSS at baseline, first follow-up, and last follow-up was 18 (range, 15 to 34), 17 (range, 0 to 32), and 13 (range, 0 to 34), respectively. The mean patient declines in IPSS from baseline to first and last follow-up were -3.6 points (p < 0.0004) and -6.9 points (p < 0.0001), respectively. At last follow-up, 43 men (54%) took GU medications. Pre-RT IPSS {>=}15 vs. {<=}14 was associated with a higher incidence of Grade {>=}2 acute GU toxicity (64% vs. 42%, p = 0.0005), and 4-year freedom from Grade {>=}2 late GU toxicity was 38% vs. 64% (p < 0.0001). There was no greatly increased risk of Grade {>=}3 late GU toxicity for men with IPSS {>=}15 (4-year freedom from Grade {>=}3 late GU toxicity of 90% vs. 96%, p = 0.0964). Conclusions: Although the improvement is not immediate, men with moderate to severe obstructive GU symptoms can have improvement in urinary function after EBRT, without significant risk for severe morbidity.

  18. Combination of external-beam radiotherapy with intraoperative electron-beam therapy is effective in incompletely resected pediatric malignancies

    SciTech Connect

    Oertel, Susanne; Niethammer, Andreas G.; Krempien, Robert . E-mail: robert_krempien@med.uni-heidelberg.de; Roeder, Falk; Eble, Michael J.; Baer, Claudia; Huber, Peter E.; Kulozik, Andreas; Waag, Karl-Ludwig; Treiber, Martina; Debus, Juergen

    2006-01-01

    Purpose: Intraoperative electron-beam radiotherapy (IOERT) has been applied for local dose escalation in over 1,400 patients in Heidelberg since 1991. Among these were 30 children, in 18 of whom IOERT was employed in radiation treatment with external-beam radiotherapy (EBRT) on account of incomplete resection. We address the question whether IOERT is able to compensate for microscopic or macroscopic tumor residue if employed in the overall radiation regimen. Methods and Materials: The data of the aforementioned 18 children were analyzed with regard to local recurrence, overall survival, and complication rates. All children suffered from either sarcomas or neuroblastomas. In all children, IOERT was employed for local dose escalation after or before EBRT. Results: After a median follow-up of 60.5 months, 15 of the treated children are alive. One local failure has been observed. Six children show clinically significant late morbidity, including the loss of a treated limb (Radiation Therapy Oncology Group Grade 4 [RTOG 4]), a severe nerve lesion (RTOG 3), an orthopedic complication (RTOG 2), a ureteral stenosis (not clinically significant), and a kidney hypotrophy (not clinically significant). In 1 child a fracture due to radionecrosis (RTOG 4) was diagnosed; however, in the follow-up, local tumor relapse was diagnosed as another possible reason for the fracture. Conclusions: Regarding the low incidence of local failure, IOERT seems to be able to compensate incomplete tumor resection in childhood sarcoma and neuroblastoma patients. The incidence of late morbidity is low enough to justify the employment of IOERT as part of the radiation treatment regimen for pediatric patients.

  19. Survey of Stereotactic Body Radiation Therapy in Japan by the Japan 3-D Conformal External Beam Radiotherapy Group

    SciTech Connect

    Nagata, Yasushi Hiraoka, Masahiro; Mizowaki, Takashi; Narita, Yuichiro; Matsuo, Yukinori; Norihisa, Yoshiki; Onishi, Hiroshi; Shirato, Hiroki

    2009-10-01

    Purpose: To recognize the current status of stereotactic body radiotherapy (SBRT) in Japan, using a nationwide survey conducted by the Japan 3-D Conformal External Beam Radiotherapy Group. Methods and Materials: The questionnaire was sent by mail to 117 institutions. Ninety-four institutions (80%) responded by the end of November 2005. Fifty-three institutions indicated that they have already started SBRT, and 38 institutions had been reimbursed by insurance. Results: A total of 1111 patients with histologically confirmed lung cancer were treated. Among these patients, 637 had T1N0M0 and 272 had T2N0M0 lung cancer. Metastatic lung cancer was found in 702 and histologically unconfirmed lung tumor in 291 patients. Primary liver cancer was found in 207 and metastatic liver cancer in 76 patients. The most frequent schedule used for primary lung cancer was 48Gy in 4 fractions at 22 institutions (52%), followed by 50Gy in 5 fractions at 11 institutions (26%) and 60Gy in 8 fractions at 4 institutions (10%). The tendency was the same for metastatic lung cancer. The average number of personnel involved in SBRT was 1.8 radiation oncologists, including 1.1 certified radiation oncologists, 2.8 technologists, 0.7 nurses, and 0.6 certified quality assurance personnel and 0.3 physicists. The most frequent amount of time for treatment planning was 61-120min, for quality assurance was 50-60min, and for treatment was 30min. There were 14 (0.6% of all cases) reported Grade 5 complications: 11 cases of radiation pneumonitis, 2 cases of hemoptysis, and 1 case of radiation esophagitis. Conclusion: The current status of SBRT in Japan was surveyed.

  20. External beam radiotherapy for palliation of painful bone metastases: pooled data bioeffect dose response analysis of dose fractionation

    NASA Astrophysics Data System (ADS)

    Naveen, T.; Supe, Sanjay S.; Ganesh, K. M.; Samuel, Jacob

    2009-01-01

    Bone metastases develop in up to 70% of newly diagnosed cancer patients and result in immobility, anxiety, and depression, severely diminishing the patients quality of life. Radiotherapy is a frequently used modality for bone metastasis and has been shown to be effective in reducing metastatic bone pain and in some instances, causing tumor shrinkage or growth inhibition. There is controversy surrounding the optimal fractionation schedule and total dose of external beam radiotherapy, despite many randomized trials and overviews addressing the issue. This study was undertaken to apply BED to clinical fractionation data of radiotherapeutic management of bone metastases in order to arrive at optimum BED values for acceptable level of response rate. A computerised literature search was conducted to identify all prospective clinical studies that addressed the issue of fractionation for the treatment of bone metastasis. The results of these studies were pooled together to form the database for the analysis. A total of 4111 number of patients received radiation dose ranging from 4 to 40.5 Gy in 1 to 15 fractions with dose per fraction ranging from 2 to 10 Gy. Single fraction treatments were delivered in 2013 patients and the dose varied from 4 to 10 Gy. Multifraction treatments were delivered in 2098 patients and the dose varied from 15 to 40.5 Gy. The biological effective dose (BED) was evaluated for each fractionation schedule using the linear quadratic model and an α/β value of 10 Gy. Response rate increased significantly beyond a BED value of 14.4 Gy (p < 0.01). Based on our analysis and indications from the literature about higher retreatment and fracture rate of single fraction treatments, minimum BED value of 14.4 Gy is recommended.

  1. Radical External Beam Radiotherapy for Clinically Localized Prostate Cancer in Japan: Changing Trends in the Patterns of Care Process Survey

    SciTech Connect

    Ogawa, Kazuhiko; Nakamura, Katsumasa; Sasaki, Tomonari; Onishi, Hiroshi; Koizumi, Masahiko; Araya, Masayuki; Mukumoto, Nobutaka; Teshima, Teruki; Mitsumori, Michihide

    2011-12-01

    Purpose: To delineate changing trends in radical external beam radiotherapy (EBRT) for prostate cancer in Japan. Methods and Materials: Data from 841 patients with clinically localized prostate cancer treated with EBRT in the Japanese Patterns of Care Study (PCS) from 1996 to 2005 were analyzed. Results: Significant increases in the proportions of patients with stage T1 to T2 disease and decrease in prostate-specific antigen values were observed. Also, there were significant increases in the percentages of patients treated with radiotherapy by their own choice. Median radiation doses were 65.0 Gy and 68.4 Gy from 1996 to 1998 and from 1999 to 2001, respectively, increasing to 70 Gy from 2003 to 2005. Moreover, conformal therapy was more frequently used from 2003 to 2005 (84.9%) than from 1996 to 1998 (49.1%) and from 1999 to 2001 (50.2%). On the other hand, the percentage of patients receiving hormone therapy from 2003 to 2005 (81.1%) was almost the same as that from 1996 to 1998 (86.3%) and from 1999 to 2001 (89.7%). Compared with the PCS in the United States, patient characteristics and patterns of treatments from 2003 to 2005 have become more similar to those in the United States than those from 1996 to 1998 and those from 1999 to 2001. Conclusions: This study indicates a trend toward increasing numbers of patients with early-stage disease and increasing proportions of patients treated with higher radiation doses with advanced equipment among Japanese prostate cancer patients treated with EBRT during 1996 to 2005 survey periods. Patterns of care for prostate cancer in Japan are becoming more similar to those in the United States.

  2. Determining the role of external beam radiotherapy in unresectable intrahepatic cholangiocarcinoma: a retrospective analysis of 84 patients

    PubMed Central

    2010-01-01

    Background Intrahepatic cholangiocarcinoma (ICC) is the second most common type of primary liver cancer. Only few studies have focused on palliative radiotherapy used for patients who weren't suitable for resection by surgery. This study was conducted to investigate the effect of external beam radiotherapy (EBRT) for patients with unresectable ICC. Methods We identified 84 patients with ICC from December 1998 through December 2008 for retrospective analysis. Thirty-five of 84 patients received EBRT therapy five times a week (median dose, 50 Gy; dose range, 30-60 Gy, in fractions of 1.8-2.0 Gy daily; EBRT group); the remaining 49 patients comprised the non-EBRT group. Tumor response, jaundice relief, and survival rates were compared by Kaplan-Meier analysis. Patient records were reviewed and compared using Cox proportional hazard analysis to determine factors that affect survival time in ICC. Results After EBRT, complete response (CR) and partial response (PR) of primary tumors were observed in 8.6% and 28.5% of patients, respectively, and CR and PR of lymph node metastases were observed in 20% and 40% of patients. In 19 patients with jaundice, complete and partial relief was observed in 36.8% and 31.6% of patients, respectively. Median survival times were 5.1 months for the non-EBRT group and 9.5 months for the EBRT group (P = 0.003). One-and two-year survival rates for EBRT versus non-EBRT group were 38.5% versus 16.4%, and 9.6% versus 4.9%, respectively. Multivariate analysis revealed that clinical symptoms, larger tumor size, no EBRT, multiple nodules and synchronous lymph node metastases were associated with poorer prognosis. Conclusions EBRT as palliative care appears to improve prognosis and relieve the symptom of jaundice in patients with unresectable ICC. PMID:20840777

  3. Californium versus cobalt brachytherapy combined with external-beam radiotherapy for IIB stage cervical cancer: long-term experience of a single institute

    PubMed Central

    Janulionis, Ernestas; Valuckas, Konstantinas Povilas; Samerdokiene, Vitalija; Atkocius, Vydmantas

    2015-01-01

    Purpose The purpose of this paper was to observe and compare long-term curative effects and complications of FIGO stage IIB cervical cancer patients (n = 232) treated with high-dose-rate (HDR) californium (252Cf) neutron or cobalt (60Co) photon intracavitary brachytherapy (ICBT) combined with external-beam radiotherapy (EBRT). Material and methods The EBRT dose to the small pelvis was 50 Gy in both groups. The brachytherapy component of 252Cf or 60Co was added in the 3rd week of EBRT, 5 fractions were performed once per week resulting in a total ICBT dose of 40 Gy/Gyeq (point A). Results Overall survival (OS) at 5, 10 and 15 years was 63.6%, 50.4% and 38.8% in the 252Cf group and 62.2%, 50.5%, 39.9%, in the 60Co group, respectively (p = 0.74). The percentage of tumour recurrence was statistically significantly lower in the 252Cf group with 7.4% versus 17.1% in the 60Co group (p = 0.02). Second primary cancers have developed similarly 9.1% and 8.1% cases for 252Cf and 60Co groups, respectively. Conclusions Our long-term retrospective study comparing 252Cf and 60Co isotopes with brachytherapy in combined treatment of FIGO IIB stage cervix carcinoma patients shows, that overall survival in the both groups are similar. However, the recurrence of tumour was significantly lower in the 252Cf group. The incidence of second primary cancers was similar in both groups. PMID:26622239

  4. ON THE DOUBLE NATURED SOLUTIONS OF THE TWO-TEMPERATURE EXTERNAL SOFT PHOTON COMPTONIZED ACCRETION DISKS

    SciTech Connect

    Meirelles Filho, Cesar

    2009-08-01

    We have analyzed pair production in the innermost region of a two-temperature external soft photon Comptonized accretion disk. We have shown that, if the viscosity parameter is greater than a critical value {alpha}{sub c}, the solution to the disk equation is double valued: one, advection dominated, and the other, radiation dominated. When {alpha} {<=} {alpha}{sub c}, the accretion rate has to satisfy m-dot{sub 1}{<=}m-dot{<=}m-dot{sub c} in order to have two steady-state solutions. It is shown that these critical parameters m-dot{sub 1}, m-dot{sub c} are functions of r, {alpha}, and {theta}{sub e}, and {alpha}{sub c} is a function of r and {theta}{sub e}. Depending on the combination of the parameters, the advection-dominated solution may not be physically consistent. It is also shown that the electronic temperature is maximum at the onset of the thermal instability, from which results this inner region. These solutions are stable against perturbations in the electron temperature and in the density of pairs.

  5. Combined treatment of anaplastic thyroid carcinoma with surgery, chemotherapy, and hyperfractionated accelerated external radiotherapy

    SciTech Connect

    De Crevoisier, Renaud . E-mail: rdecrevo@mdanderson.org; Baudin, Eric; Bachelot, Anne; Leboulleux, Sophie; Travagli, Jean-Paul; Caillou, Bernard; Schlumberger, Martin

    2004-11-15

    Purpose: To analyze a prospective protocol combining surgery, chemotherapy (CT), and hyperfractionated accelerated radiotherapy (RT) in anaplastic thyroid carcinoma. Methods and materials: Thirty anaplastic thyroid carcinoma patients (mean age, 59 years) were treated during 1990-2000. Tumor extended beyond the capsule gland in 26 patients, with tracheal extension in 8. Lymph node metastases were present in 18 patients and lung metastases in 6. Surgery was performed before RT-CT in 20 patients and afterwards in 4. Two cycles of doxorubicin (60 mg/m{sup 2}) and cisplatin (120 mg/m{sup 2}) were delivered before RT and four cycles after RT. RT consisted of two daily fractions of 1.25 Gy, 5 days per week to a total dose of 40 Gy to the cervical lymph node areas and the superior mediastinum. Results: Acute toxicity (World Health Organization criteria) was Grade 3 or 4 pharyngoesophagitis in 10 patients; Grade 4 neutropenia in 21, with infection in 13; and Grade 3 or 4 anemia and thrombopenia in 8 and 4, respectively. At the end of the treatment, a complete local response was observed in 19 patients. With a median follow-up of 45 months (range, 12-78 months), 7 patients were alive in complete remission, of whom 6 had initially received a complete tumor resection. Overall survival rate at 3 years was 27% (95% confidence interval 10-44%) and median survival 10 months. In multivariate analysis, tracheal extension and macroscopic complete tumor resection were significant factors in overall survival. Death was related to local progression in 5% of patients, to distant metastases in 68%, and to both in 27%. Conclusions: Main toxicity was hematologic. High long-term survival was obtained when RT-CT was given after complete surgery. This protocol avoided local tumor progression, and death was mainly caused by distant metastases.

  6. Residual motion of lung tumors in end-of-inhale respiratory gated radiotherapy based on external surrogates

    SciTech Connect

    Berbeco, Ross I.; Nishioka, Seiko; Shirato, Hiroki; Jiang, Steve B.

    2006-11-15

    It has been noted that some lung tumors exhibit large periodic motion due to respiration. To limit the amount of dose to healthy lung tissues, many clinics have begun gating radiotherapy treatment using externally placed surrogates. It has been observed by several institutions that the end-of-exhale (EOE) tumor position is more reproducible than other phases of the breathing cycle, so the gating window is often set there. From a treatment planning perspective, end-of-inhale (EOI) phase might be preferred for gating because the expanded lungs will further decrease the healthy tissue within the treatment field. We simulate gated treatment at the EOI phase, using a set of recently measured internal/external anatomy patient data. This paper attempts to answer three questions: (1) How much is the tumor residual motion when we use an external surrogate gating window at EOI? (2) How could we reduce the residual motion in the EOI gating window? (3) Is there a preference for amplitude- versus phase-based gating at EOI? We found that under free breathing conditions the residual motion of the tumors is much larger for EOI phase than for EOE phase. The mean values of residual motion at EOI were found to be 2.2 and 2.7 mm for amplitude- and phase-based gating, respectively, and, at EOE, 1.0 and 1.2 mm for amplitude- and phase-based gating, respectively. However, we note that the residual motion in the EOI gating window is correlated well with the reproducibility of the external surface position in the EOI phase. Using the results of a published breath-coaching study, we deduce that the residual motion of a lung tumor at EOI would approach that at EOE, with the same duty cycle (30%), under breath-coaching conditions. Additionally, we found that under these same conditions, phase-based gating approaches the same residual motion as amplitude-based gating, going from a 28% difference to 11%, for the patient with the largest difference between the two gating modalities. We conclude

  7. Precision radiotherapy for cancer of the pancreas: technique and results. [Photons and electrons

    SciTech Connect

    Dobelbower, R.R. Jr.; Borgelt, B.B.; Strubler, K.A.; Kutcher, G.J.; Suntharalingam, N.

    1980-09-01

    Forty patients with locally extensive, unresectable adenocarcinoma of the pancreas received precision high dose (PHD) radiation therapy with a 45 MeV betatron. PHD radiotherapy was generally well tolerated. During treatment, only 7 patients experienced significant nausea, vomiting, diarrhea or anorexia. Late gastrointestinal radiation reactions were observed in 7 patients. Twelve patients received adjuvant chemotherapy. The projected survival of patients with unresectable pancreatic cancer treated with PHD radiotherapy is comparable to that of patients with resectable disease operated on for cure. The projected one year survival rate is 49%.

  8. External Beam Radiotherapy With Endocavitary Boost for Nasopharyngeal Cancer: Treatment Results and Late Toxicity After Extended Follow-Up

    SciTech Connect

    Schinagl, Dominic A.X.; Marres, Henri A.M.; Kappelle, Arnoud C.; Merkx, Matthias A.W.; Pop, Lucas A.M.; Verstappen, Suzan M.M.; Kaanders, Johannes H.A.M.

    2010-11-01

    Purpose: To evaluate the long-term outcome after treatment of nasopharyngeal carcinoma and assess late toxicity in a multidisciplinary clinic. Methods and Materials: A retrospective analysis of 117 patients treated for nasopharyngeal cancer in a single institute between 1985 and 2002 was performed. Fifty-one long-term survivors were evaluated for late toxicity by a multidisciplinary team comprising a radiation oncologist, otolaryngologist, neurologist, and oral and maxillofacial surgeon. Results: The 5-year local control rate for T1 to T2 and T3 to T4 tumors was 97% and 76%, respectively. Five-year disease-free survival and overall survival were 82% and 88% for Stage I to IIb disease and 46% and 52% for Stage III to IVb, respectively. Late morbidity evaluation revealed Radiation Therapy Oncology Group (RTOG) Grade III to IV toxicity in 71% of patients. A high incidence of cranial nerve palsies (47%) and mandibular osteolysis (82%) was found, although these complications had limited clinical impact. Conclusions: The multidisciplinary late morbidity clinic revealed an unexpected high incidence of cranial nerve palsies and mandibular osteolysis and overall an RTOG Grade III to IV toxicity in 71% of patients treated for nasopharyngeal cancer. External beam radiotherapy with endocavitary brachytherapy produces excellent rates of local control for T1 to T2 tumors, but the high incidence of late toxicity suggests an overtreatment.

  9. Predictors of severe gastrointestinal toxicity after external beam radiotherapy and interstitial brachytherapy for advanced or recurrent gynecologic malignancies

    SciTech Connect

    Kasibhatla, Mohit . E-mail: Mohit.S.Kasibhatla@Hitchcock.org; Clough, Robert W. B.A.; Montana, Gustavo S.; Oleson, James R.; Light, Kim C.; Steffey, Beverley A.; Jones, Ellen L.

    2006-06-01

    Purpose: The aim of this retrospective review of patients with gynecologic malignancies treated with external beam radiotherapy (EBRT) and interstitial brachytherapy was to determine the rate of Grade {>=}2 rectovaginal fistula and Grade {>=}4 small bowel obstruction as defined by the National Cancer Institute Common Toxicity Criteria for Adverse Events, version 3.0. Methods and Materials: Thirty-six patients with primary and recurrent gynecologic cancers were treated with EBRT and interstitial brachytherapy. Median doses to tumor, bladder, and rectum were 75 Gy, 61 Gy, and 61 Gy, respectively. A univariate analysis was performed to identify variables that correlated with toxicity. Results: At median follow-up of 19 months, the 3-year risk of small bowel obstruction was 6%. Those patients with prior abdomino-pelvic surgery who received EBRT with antero-posterior fields had higher rates of obstruction than patients without prior abdomino-pelvic surgery or those who received EBRT with four fields (50% vs. 0%, p < 0.0001). The 3-year risk of rectovaginal fistula was 18% and was significantly higher in patients who received >76 Gy to the rectum compared with those who received {<=}76 Gy (100% vs. 7%, p = 0.009). Conclusions: Patients treated with EBRT and interstitial brachytherapy after abdomino-pelvic surgery should receive EBRT with four fields and the cumulative rectal dose should be {<=}76 Gy.

  10. Radrue method for reconstruction of external photon doses for Chernobyl liquidators in epidemiological studies.

    PubMed

    Kryuchkov, Victor; Chumak, Vadim; Maceika, Evaldas; Anspaugh, Lynn R; Cardis, Elisabeth; Bakhanova, Elena; Golovanov, Ivan; Drozdovitch, Vladimir; Luckyanov, Nickolas; Kesminiene, Ausrele; Voillequé, Paul; Bouville, André

    2009-10-01

    Between 1986 and 1990, several hundred thousand workers, called "liquidators" or "clean-up workers," took part in decontamination and recovery activities within the 30-km zone around the Chernobyl nuclear power plant in Ukraine, where a major accident occurred in April 1986. The Chernobyl liquidators were mainly exposed to external ionizing radiation levels that depended primarily on their work locations and the time after the accident when the work was performed. Because individual doses were often monitored inadequately or were not monitored at all for the majority of liquidators, a new method of photon (i.e., gamma and x rays) dose assessment, called "RADRUE" (Realistic Analytical Dose Reconstruction with Uncertainty Estimation), was developed to obtain unbiased and reasonably accurate estimates for use in three epidemiologic studies of hematological malignancies and thyroid cancer among liquidators. The RADRUE program implements a time-and-motion dose-reconstruction method that is flexible and conceptually easy to understand. It includes a large exposure rate database and interpolation and extrapolation techniques to calculate exposure rates at places where liquidators lived and worked within approximately 70 km of the destroyed reactor. The RADRUE technique relies on data collected from subjects' interviews conducted by trained interviewers, and on expert dosimetrists to interpret the information and provide supplementary information, when necessary, based upon their own Chernobyl experience. The RADRUE technique was used to estimate doses from external irradiation, as well as uncertainties, to the bone marrow for 929 subjects and to the thyroid gland for 530 subjects enrolled in epidemiologic studies. Individual bone marrow dose estimates were found to range from less than one muGy to 3,300 mGy, with an arithmetic mean of 71 mGy. Individual thyroid dose estimates were lower and ranged from 20 muGy to 507 mGy, with an arithmetic mean of 29 mGy. The

  11. RADRUE METHOD FOR RECONSTRUCTION OF EXTERNAL PHOTON DOSES TO CHERNOBYL LIQUIDATORS IN EPIDEMIOLOGICAL STUDIES

    PubMed Central

    Kryuchkov, Victor; Chumak, Vadim; Maceika, Evaldas; Anspaugh, Lynn R.; Cardis, Elisabeth; Bakhanova, Elena; Golovanov, Ivan; Drozdovitch, Vladimir; Luckyanov, Nickolas; Kesminiene, Ausrele; Voillequé, Paul; Bouville, André

    2010-01-01

    Between 1986 and 1990, several hundred thousand workers, called “liquidators” or “clean-up workers”, took part in decontamination and recovery activities within the 30-km zone around the Chernobyl nuclear power plant in Ukraine, where a major accident occurred in April 1986. The Chernobyl liquidators were mainly exposed to external ionizing radiation levels that depended primarily on their work locations and the time after the accident when the work was performed. Because individual doses were often monitored inadequately or were not monitored at all for the majority of liquidators, a new method of photon (i.e. gamma and x-rays) dose assessment, called “RADRUE” (Realistic Analytical Dose Reconstruction with Uncertainty Estimation) was developed to obtain unbiased and reasonably accurate estimates for use in three epidemiologic studies of hematological malignancies and thyroid cancer among liquidators. The RADRUE program implements a time-and-motion dose reconstruction method that is flexible and conceptually easy to understand. It includes a large exposure rate database and interpolation and extrapolation techniques to calculate exposure rates at places where liquidators lived and worked within ~70 km of the destroyed reactor. The RADRUE technique relies on data collected from subjects’ interviews conducted by trained interviewers, and on expert dosimetrists to interpret the information and provide supplementary information, when necessary, based upon their own Chernobyl experience. The RADRUE technique was used to estimate doses from external irradiation, as well as uncertainties, to the bone-marrow for 929 subjects and to the thyroid gland for 530 subjects enrolled in epidemiologic studies. Individual bone-marrow dose estimates were found to range from less than one μGy to 3,300 mGy, with an arithmetic mean of 71 mGy. Individual thyroid dose estimates were lower and ranged from 20 μGy to 507 mGy, with an arithmetic mean of 29 mGy. The

  12. Modeling of an industrial environment: external dose calculations based on Monte Carlo simulations of photon transport.

    PubMed

    Kis, Zoltán; Eged, Katalin; Voigt, Gabriele; Meckbach, Reinhard; Müller, Heinz

    2004-02-01

    External gamma exposures from radionuclides deposited on surfaces usually result in the major contribution to the total dose to the public living in urban-industrial environments. The aim of the paper is to give an example for a calculation of the collective and averted collective dose due to the contamination and decontamination of deposition surfaces in a complex environment based on the results of Monte Carlo simulations. The shielding effects of the structures in complex and realistic industrial environments (where productive and/or commercial activity is carried out) were computed by the use of Monte Carlo method. Several types of deposition areas (walls, roofs, windows, streets, lawn) were considered. Moreover, this paper gives a summary about the time dependence of the source strengths relative to a reference surface and a short overview about the mechanical and chemical intervention techniques which can be applied in this area. An exposure scenario was designed based on a survey of average German and Hungarian supermarkets. In the first part of the paper the air kermas per photon per unit area due to each specific deposition area contaminated by 137Cs were determined at several arbitrary locations in the whole environment relative to a reference value of 8.39 x 10(-4) pGy per gamma m(-2). The calculations provide the possibility to assess the whole contribution of a specific deposition area to the collective dose, separately. According to the current results, the roof and the paved area contribute the most part (approximately 92%) to the total dose in the first year taking into account the relative contamination of the deposition areas. When integrating over 10 or 50 y, these two surfaces remain the most important contributors as well but the ratio will increasingly be shifted in favor of the roof. The decontamination of the roof and the paved area results in about 80-90% of the total averted collective dose in each calculated time period (1, 10, 50 y

  13. Extramedullary Plasmacytoma of the Paranasal Sinuses: Combining Surgery with External Radiotherapy.

    PubMed

    Vlad, Diana; Trombitas, Veronica; Albu, Silviu

    2016-03-01

    Extramedullary plasmacytomas (EMP) are rare neoplasms characterized by the proliferation of a single B-lymphoid cell clone, arising primarily in the head and neck region. The purpose of this study is to report our experience in the management of EMPs arising in the paranasal sinuses. We retrospectively reviewed clinical records of 7 patients (4 men and 3 women), admitted between 1995 and 2010 for EMPs of the paranasal sinuses-5 within the ethmoid and 2 in the maxillary sinus. Treatment consisted in endoscopic resection followed by external RT. The mean follow-up period is 50 months (range 9-67 months). Local recurrences developed in 2 out of 7 cases. Both recurrences occurred in maxillary EMPs and they underwent salvage treatment-combination of RT and surgery. At the time of analyzing these data 5 patients (70 %) were alive and two (30 %) have died of their disease. A single patient, presenting local relapse at 6 months, died due to the disease at 9 months. One patient progressed to multiple myeloma. Larger controlled clinical trials are necessary to establish an optimal treatment of choice that implies an individualized management of these patients. PMID:27066407

  14. Methods for the measurement of the refractive index of MeV photons using total internal and external reflection

    NASA Astrophysics Data System (ADS)

    Aginian, M. A.; Ispirian, K. A.; Ispiryan, M.

    2014-05-01

    Recently it has been theoretically and experimentally shown that for 1-10 MeV and 1-2 MeV photons, respectively, the refractive index of Si is greater than 1. Taking into account the difficulties of the carried out experiment it is proposed to measure directly the refractive index of Si and other materials detecting the total internal and external reflections.

  15. Daily targeting of liver tumors: Screening patients with a mock treatment and using a combination of internal and external fiducials for image-guided respiratory-gated radiotherapy

    SciTech Connect

    Krishnan, Sunil; Briere, Tina Marie; Dong Lei; Murthy, Ravi; Ng, Chaan; Balter, Peter; Mohan, Radhe; Gillin, Michael T.; Beddar, A. Sam

    2007-12-15

    The feasibility and accuracy of using a mock treatment to screen suitable patients for respiratory-gated image-guided radiotherapy was investigated. Radio-opaque fiducials implanted adjacent to the liver tumor were used for online positioning to minimize the systematic error in patient positioning. The consistency in the degree of correlation between the external and internal fiducials was analyzed during a mock treatment. This technique could screen patients for gated therapy, reduce setup inaccuracy, and possibly individualize treatment margins.

  16. WE-D-BRE-03: Late Toxicity Following Photon Or Proton Radiotherapy in Patients with Brain Tumors

    SciTech Connect

    Munbodh, R; Ding, X; Yin, L; Anamalayil, S; Dorsey, J; Lustig, R; Alonso-Basanta, M

    2014-06-15

    Purpose: To identify indicators of Late Grade 3 (LG3) toxicity, late vision and hearing changes in patients treated for primary brain tumors with photon (XRT) or proton radiotherapy (PRT). Methods: We retrospectively reviewed 102 patients who received brain XRT or PRT to doses of 54 or 59.6 Gy in daily fractions of 1.8–2 Gy. Of the 80 patients (34 XRT, 39 PRT and 7 both modalities) reviewed for indicators of LG3 toxicity, 25 developed LG3 toxicity 90 to 500 days after radiotherapy completion. 55 patients had less than LG3 toxicity > 500 days after treatment. In that time, late vision and hearing changes were seen in 44 of 75 and 25 of 78 patients, respectively. The correlation between late toxicity and prescription dose, planning target volume (PTV) size, and doses to the brainstem, brain, optic chiasm, optic nerves, eyes and cochlea was evaluated. A two-tailed Fisher's exact test and Wilcoxon rank sum test were used for the statistical analysis for XRT, PRT and all patients combined. Results: Exceeding the 54 Gy-5% dose-volume brainstem constraint, but not the optic structure constraints, was significantly correlated (p < 0.05) with late vision changes in all three groups. Exceeding maximum and mean cochlear doses of 45 and 30 Gy, respectively, was a significant indicator of hearing changes (p < 0.05) in PRT patients and all patients combined. In a sub-group of 52 patients in whom the brain was contoured, the absolute brain volume receiving ≤ 50 Gy and > 60 Gy was significantly larger in patients with LG3 toxicity for all patients combined (p < 0.05). Prescription dose, brainstem dose and PTV volume were not correlated to LG3 toxicity. Conclusion: Our results indicate the importance of minimizing the brain volume irradiated, and brainstem and cochlea doses to reduce the risk of late toxicities following brain radiotherapy.

  17. The Relationship Between Local Recurrence and Radiotherapy Treatment Volume for Soft Tissue Sarcomas Treated With External Beam Radiotherapy and Function Preservation Surgery

    SciTech Connect

    Dickie, Colleen I.; Griffin, Anthony M.; Parent, Amy L.; Chung, Peter W.M.; Catton, Charles N.; Svensson, Jon; Ferguson, Peter C.; Wunder, Jay S.; Bell, Robert S.; Sharpe, Michael B.; O'Sullivan, Brian

    2012-03-15

    Purpose: To examine the geometric relationship between local recurrence (LR) and external beam radiotherapy (RT) volumes for soft-tissue sarcoma (STS) patients treated with function-preserving surgery and RT. Methods and Materials: Sixty of 768 (7.8%) STS patients treated with combined therapy within our institution from 1990 through 2006 developed an LR. Thirty-two received preoperative RT, 16 postoperative RT, and 12 preoperative RT plus a postoperative boost. Treatment records, RT simulation images, and diagnostic MRI/CT data sets of the original and LR disease were retrospectively compared. For LR location analysis, three RT target volumes were defined according to the International Commission on Radiation Units and Measurements 29 as follows: (1) the gross tumor or operative bed; (2) the treatment volume (TV) extending 5 cm longitudinally beyond the tumor or operative bed unless protected by intact barriers to spread and at least 1-2 cm axially (the TV was enclosed by the isodose curve representing the prescribed target absorbed dose [TAD] and accounted for target/patient setup uncertainty and beam characteristics), and (3) the irradiated volume (IRV) that received at least 50% of the TAD, including the TV. LRs were categorized as developing in field within the TV, marginal (on the edge of the IRV), and out of field (occurring outside of the IRV). Results: Forty-nine tumors relapsed in field (6.4% overall). Nine were out of field (1.1% overall), and 2 were marginal (0.3% overall). Conclusions: The majority of STS tumors recur in field, indicating that the incidence of LR may be affected more by differences in biologic and molecular characteristics rather than aberrations in RT dose or target volume coverage. In contrast, only two patients relapsed at the IRV boundary, suggesting that the risk of a marginal relapse is low when the TV is appropriately defined. These data support the accurate delivery of optimal RT volumes in the most precise way using advanced

  18. Clinical assessment of three-dimensional ultrasound prostate localization for external beam radiotherapy

    SciTech Connect

    Orton, Nigel P.; Jaradat, Hazim A.; Tome, Wolfgang A.

    2006-12-15

    Three-dimensional ultrasound localization has been performed for external beam prostate treatments at our institution since September 2001. This article presents data from the daily shifts for 221 patients and 5005 fractions, and the results of tests performed to assess the system's performance under clinical conditions. Three tests are presented: (1) To measure the accuracy of the shifts, eight patients treated on a helical tomotherapy machine were localized daily using both ultrasound (US) and a megavoltage computed tomography (MVCT) scan. Comparison of the shifts showed that US localization improved alignment for six of the eight patients when compared to alignment using skin marks alone. The mean US-MVCT vector for these six patients was 3.1{+-}1.3 mm, compared to 5.1{+-}2.1 mm between the MVCT and the skin marks. The other two patients were identified as poor candidates for US prior to their first treatment fraction. (2) To assess the extent of intrafraction motion, US localization was repeated after treatment for six patients and a total of 29 fractions. The mean intrafraction prostate shift was 1.9{+-}1.0 mm, and the shift was within the 3 mm localization uncertainty [Tome et al., Med. Phys. 29, 1781-1788 (2002); in New Technologies in Radiotion Oncology, edited by W. Schlegel, T. Bortfelde, and A. Grosu (Springer, Berlin, 2005)] of the system for 25 of 29 fractions. (3) To assess the interuser variation in shifts, four experienced operators independently localized five patients for five consecutive fractions. The standard deviation of the users' shifts was found to be approximately the same as the system's localization uncertainty. For shifts larger than the system localization uncertainty, the standard deviation of the users' shifts was nearly always much smaller than the mean shift. Taken together with the results of the US-MVCT comparison, this indicates that the shifts improved patient localization despite differences between users.

  19. Brachytherapy or Conformal External Radiotherapy for Prostate Cancer: A Single-Institution Matched-Pair Analysis

    SciTech Connect

    Pickles, Tom; Keyes, Mira; Morris, W. James

    2010-01-15

    Purpose: In the absence of randomized study data, institutional case series have shown brachytherapy (BT) to produce excellent biochemical control (bNED) in patients with localized prostate cancer compared with alternative curative treatments. This study was designed to overcome some of the limitations of case series studies by using a matched-pair design in patients treated contemporaneously with BT and external beam radiation therapy (EBRT) at a single institution. Methods and Materials: Six hundred one eligible patients treated between 1998 and 2001 were prospectively followed up in our institutional databases and matched on a 1:1 basis for the following known prognostic variables: prostate-specific antigen (PSA) level, Gleason score, T stage, the use and duration of neoadjuvant androgen deprivation therapy, and the percentage of positive tissue core samples. Two hundred seventy-eight perfect matches of patients (139 in each group) with low- and intermediate-risk cancer were further analyzed. bNED (Phoenix definition) was the primary endpoint. Other endpoints were toxicity, PSA kinetics, and the secondary use of androgen deprivation therapy. Results: The 5-year bNED rates were 95% (BT) and 85% (EBRT) (p < 0.001). After 7 years, the BT bNED result was unchanged, but the rate in EBRT patients had fallen to 75%. The median posttreatment PSA nadirs were 0.04 ng/mL (BT) and 0.62 ng/mL (EBRT, p < 0.001), which predicted a higher ongoing treatment failure rate in association with EBRT use than with BT use. Late urinary toxicity and rectal/bowel toxicity were worse in patients treated with BT and EBRT, respectively. Conclusions: BT for both low-risk and selected intermediate-risk cancers achieves exceptional cure rates. Even with dose escalation, it will be difficult for EBRT to match the proven track record of BT seen over the past decade.

  20. SU-E-T-415: An Ionization Chamber Array with High Spatial Resolution for External Beam Radiotherapy

    SciTech Connect

    Togno, M; Wilkens, J; Menichelli, D

    2014-06-01

    Purpose: To characterize an ionization chamber array technology with high spatial resolution and high charge collection efficiency for external beam radiotherapy. Methods: The prototype under test is a linear array of air vented ionization chambers developed by IBA Dosimetry, consisting of 80 pixels with 3.5mm spatial resolution and 4mm{sup 3} sensitive volume. The detector was characterized in a plastic phantom with {sup 60} Co radiation and MV X-rays from an ELEKTA Agility LINAC (with flattened and unflattened beam qualities). Bias voltage was varied in order to evaluate charge collection efficiency. A commercial array of ionization chambers (MatriXX Evolution, IBA Dosimetry) and an amorphous silicon flat panel in direct conversion configuration were used as references. Results: Repeatability (0.4%) and stability under continuous gamma irradiation (0.3%) are very good, in spite of low active volume and sensitivity (∼200pC/Gy). Charge collection efficiency is higher than 99% already at 150V with ∼2mGy dose per pulse, leading to a ±1.1% sensitivity change with dose per pulse in the range 0.09-2mGy (covering all flattened and unflattened applications). Measured dose profiles are in agreement with MatriXX for fields larger than 2×2cm{sup 2}, in which case the linear array offers a much better characterization of the penumbra region. Down to 1×1cm{sup 2}, measured profiles are in very good agreement with the flat panel. Conclusion: The array represents a valuable tool for the characterization of treatment fields in which high spatial resolution is required, together with the dosimetric performance of air vented ionization chambers. Such a technology would be particularly valuable in association with advanced treatment modalities such as rotational radiotherapy, stereotactic treatments (even with unflattened beam qualities) and proton therapy, due to the insensitivity of the chambers on dose per pulse. In the future, a two dimensional prototype based on this

  1. Bowel sparing in pediatric cranio-spinal radiotherapy: a comparison of combined electron and photon and helical TomoTherapy techniques to a standard photon method

    SciTech Connect

    Harron, Elizabeth; Lewis, Joanne

    2012-07-01

    The aim of this study was to compare the dose to organs at risk (OARs) from different craniospinal radiotherapy treatment approaches available at the Northern Centre for Cancer Care (NCCC), with a particular emphasis on sparing the bowel. Method: Treatment plans were produced for a pediatric medulloblastoma patient with inflammatory bowel disease using 3D conformal 6-MV photons (3DCP), combined 3D 6-MV photons and 18-MeV electrons (3DPE), and helical photon TomoTherapy (HT). The 3DPE plan was a modification of the standard 3DCP technique, using electrons to treat the spine inferior to the level of the diaphragm. The plans were compared in terms of the dose-volume data to OARs and the nontumor integral dose. Results: The 3DPE plan was found to give the lowest dose to the bowel and the lowest nontumor integral dose of the 3 techniques. However, the coverage of the spine planning target volume (PTV) was least homogeneous using this technique, with only 74.6% of the PTV covered by 95% of the prescribed dose. HT was able to achieve the best coverage of the PTVs (99.0% of the whole-brain PTV and 93.1% of the spine PTV received 95% of the prescribed dose), but delivered a significantly higher integral dose. HT was able to spare the heart, thyroid, and eyes better than the linac-based techniques, but other OARs received a higher dose. Conclusions: Use of electrons was the best method for reducing the dose to the bowel and the integral dose, at the expense of compromised spine PTV coverage. For some patients, HT may be a viable method of improving dose homogeneity and reducing selected OAR doses.

  2. Dynamic Contrast-Enhanced Magnetic Resonance Imaging for Localization of Recurrent Prostate Cancer After External Beam Radiotherapy

    SciTech Connect

    Haider, Masoom A. Chung, Peter; Sweet, Joan; Toi, Ants; Jhaveri, Kartik; Menard, Cynthia; Warde, Padraig; Trachtenberg, John; Lockwood, Gina M.Math.; Milosevic, Michael

    2008-02-01

    Purpose: To compare the performance of T2-weighted (T2w) imaging and dynamic contrast-enhanced (DCE) magnetic resonance imaging (MRI) of the prostate gland in the localization of recurrent prostate cancer in patients with biochemical failure after external beam radiotherapy (EBRT). Methods and Materials: T2-weighted imaging and DCE MRI were performed in 33 patients with suspected relapse after EBRT. Dynamic contrast-enhanced MRI was performed with a temporal resolution of 95 s. Voxels enhancing at 46 s after injection to a greater degree than the mean signal intensity of the prostate at 618 s were considered malignant. Results from MRI were correlated with biopsies from six regions in the peripheral zone (PZ) (base, mid, and apex). The percentage of biopsy core positive for malignancy from each region was correlated with the maximum diameter of the tumor on DCE MRI with a linear regression model. Results: On a sextant basis, DCE MRI had significantly better sensitivity (72% [21of 29] vs. 38% [11 of 29]), positive predictive value (46% [21 of 46] vs. 24% [11 of 45]) and negative predictive value (95% [144 of 152] vs. 88% [135 of 153] than T2w imaging. Specificities were high for both DCE MRI and T2w imaging (85% [144 of 169] vs. 80% [135 of 169]). There was a linear relationship between tumor diameters on DCE MRI and the percentage of cancer tissue in the corresponding biopsy core (r = 0.9, p < 0.001), with a slope of 1.2. Conclusions: Dynamic contrast-enhanced MRI performs better than T2w imaging in the detection and localization of prostate cancer in the peripheral zone after EBRT. This may be helpful in the planning of salvage therapy.

  3. Retrospective Comparison of External Beam Radiotherapy and Radical Prostatectomy in High-Risk, Clinically Localized Prostate Cancer

    SciTech Connect

    Arcangeli, Giorgio; Strigari, Lidia; Arcangeli, Stefano; Petrongari, Maria Grazia; Saracino, Biancamaria; Gomellini, Sara; Papalia, Rocco; Simone, Giuseppe; De Carli, Piero; Gallucci, Michele

    2009-11-15

    Purpose: Because of the lack of conclusive and well-conducted randomized studies, the optimal therapy for prostate tumors remains controversial. The aim of this study was to retrospectively compare the results of radical surgery vs. a conservative approach such as external beam radiotherapy (EBRT) plus androgen deprivation therapy using an intent-to-treat analysis on two pretreatment defined, concurrently treated, high-risk patient populations. Methods and Materials: Between January 2003 and December 2007, 162 patients with high-risk prostate cancer underwent an EBRT plus androgen deprivation therapy program at the RT department of our institute. In the same period, 122 patients with the same high-risk disease underwent radical prostatectomy (RP) at the urologic department of our institute. Patients with adverse pathologic factors also underwent adjuvant EBRT with or without androgen deprivation therapy. The primary endpoint was freedom from biochemical failure. Results: The two groups of high-risk patients were homogeneous in terms of freedom from biochemical failure on the basis of the clinical T stage, biopsy Gleason score, and initial prostate-specific antigen level. The median follow-up was 38.6 and 33.8 months in the EBRT and RP groups, respectively. The actuarial analysis of the freedom from biochemical failure showed a 3-year rate of 86.8% and 69.8% in the EBRT and RP group, respectively (p = .001). Multivariate analysis of the whole group revealed the initial prostate-specific antigen level and treatment type (EBRT vs. RP) as significant covariates. Conclusion: This retrospective intention-to-treat analysis showed a significantly better outcome after EBRT than after RP in patients with high-risk prostate cancer, although a well-conducted randomized comparison would be the best procedure to confirm these results.

  4. NOTE Thyroid volume measurement in external beam radiotherapy patients using CT imaging: correlation with clinical and anthropometric characteristics

    NASA Astrophysics Data System (ADS)

    Veres, C.; Garsi, J. P.; Rubino, C.; Pouzoulet, F.; Bidault, F.; Chavaudra, J.; Bridier, A.; Ricard, M.; Ferreira, I.; Lefkopoulos, D.; de Vathaire, F.; Diallo, I.

    2010-11-01

    The aim of this study is to define criteria for accurate representation of the thyroid in human models used to represent external beam radiotherapy (EBRT) patients and evaluate the relationship between the volume of this organ and clinical and anthropometric characteristics. From CT images, we segmented the thyroid gland and calculated its volume for a population of 188 EBRT patients of both sexes, with ages ranging from 1 to 89 years. To evaluate uncertainties linked to measured volumes, experimental studies on the Livermore anthropomorphic phantom were performed. For our population of EBRT patients, we observed that in children, thyroid volume increased rapidly with age, from about 3 cm3 at 2 years to about 16 cm3 at 20. In adults, the mean thyroid gland volume was 23.5 ± 9 cm3 for males and 17.5 ± 8 cm3 for females. According to anthropometric parameters, the best fit for children was obtained by modeling the log of thyroid volume as a linear function of body surface area (BSA) (p < 0.0001) and age (p = 0.04) and for adults, as a linear function of BSA (p < 0.0001) and gender (p = 0.01). This work enabled us to demonstrate that BSA was the best indicator of thyroid volume for both males and females. These results should be taken into account when modeling the volume of the thyroid in human models used to represent EBRT patients for dosimetry in retrospective studies of the relationship between the estimated dose to the thyroid and long-term follow-up data on EBRT patients.

  5. Evaluation of three types of reference image data for external beam radiotherapy target localization using digital tomosynthesis (DTS)

    SciTech Connect

    Godfrey, Devon J.; Ren Lei; Yan Hui; Wu, Q.; Yoo Sua; Oldham, M.; Yin Fangfang

    2007-08-15

    Digital tomosynthesis (DTS) is a fast, low-dose three-dimensional (3D) imaging approach which yields slice images with excellent in-plane resolution, though low plane-to-plane resolution. A stack of DTS slices can be reconstructed from a single limited-angle scan, with typical scan angles ranging from 10 deg. to 40 deg. and acquisition times of less than 10 s. The resulting DTS slices show soft tissue contrast approaching that of full cone-beam CT. External beam radiotherapy target localization using DTS requires the registration of on-board DTS images with corresponding reference image data. This study evaluates three types of reference volume: original reference CT, exact reference DTS (RDTS), and a more computationally efficient approximate reference DTS (RDTS{sub approx}), as well as three different DTS scan angles (22 deg., 44 deg., and 65 deg.) for the DTS target localization task. Three-dimensional mutual information (MI) shared between reference and on-board DTS volumes was computed in a region surrounding the spine of a chest phantom, as translations spanning {+-}5 mm and rotations spanning {+-}5 deg. were simulated along each dimension in the reference volumes. The locations of the MI maxima were used as surrogates for registration accuracy, and the width of the MI peaks were used to characterize the registration robustness. The results show that conventional treatment planning CT volumes are inadequate reference volumes for direct registration with on-board DTS data. The efficient RDTS{sub approx} method also appears insufficient for MI-based registration without further refinement of the technique, though it may be suitable for manual registration performed by a human observer. The exact RDTS volumes, on the other hand, delivered a 3D DTS localization accuracy of 0.5 mm and 0.5 deg. along each axis, using only a single 44 deg. coronal on-board DTS scan of the chest phantom.

  6. Dependence of Cell Survival on Iododeoxyuridine Concentration in 35-keV Photon-Activated Auger Electron Radiotherapy

    SciTech Connect

    Dugas, Joseph P.; Varnes, Marie E.; Sajo, Erno; Welch, Christopher E.; Ham, Kyungmin; Hogstrom, Kenneth R.

    2011-01-01

    Purpose: To measure and compare Chinese hamster ovary cell survival curves using monochromatic 35-keV photons and 4-MV x-rays as a function of concentration of the radiosensitizer iododeoxyuridine (IUdR). Methods and Materials: IUdR was incorporated into Chinese hamster ovary cell DNA at 16.6 {+-} 1.9%, 12.0 {+-} 1.4%, and 9.2 {+-} 1.3% thymidine replacement. Cells were irradiated from 1 to 8 Gy with 35-keV synchrotron-generated photons and conventional radiotherapy 4-MV x-rays. The effects of the radiation were measured via clonogenic survival assays. Surviving fraction was plotted vs. dose and fit to a linear quadratic model. Sensitization enhancement ratios (SER{sub 10}) were calculated as the ratio of doses required to achieve 10% surviving fraction for cells without and with DNA-incorporated IUdR. Results: At 4 MV, SER{sub 10} values were 2.6 {+-} 0.1, 2.2 {+-} 0.1, and 1.5 {+-} 0.1 for 16.6%, 12.0%, and 9.2% thymidine replacement, respectively. At 35 keV, SER{sub 10} values were 4.1 {+-} 0.2, 3.0 {+-} 0.1, and 2.0 {+-} 0.1, respectively, which yielded SER{sub 10} ratios (35 keV:4 MV) of 1.6 {+-} 0.1, 1.4 {+-} 0.1, and 1.3 {+-} 0.1, respectively. Conclusions: SER{sub 10} increases monotonically with percent thymidine replacement by IUdR for both modalities. As compared to 4-MV x-rays, 35-keV photons produce enhanced SER{sub 10} values whose ratios are linear with percent thymidine replacement and assumed to be due to Auger electrons contributing to enhanced dose to DNA. Although this Auger effectiveness factor is less than the radiosensitization factor of IUdR, both could be important for the clinical efficacy of IUdR radiotherapy.

  7. The optimal conditions for the correlation of object pulse temporary form with the stimulated photon echo response in the presence of external spatial inhomogeneous electric fields

    NASA Astrophysics Data System (ADS)

    Garnaeva, G. I.; Nefediev, L. A.; Hakimzyanova, E. I.; Nefedieva, K. L.

    2014-08-01

    The influence of external spatially inhomogeneous electric fields on the reproducibility of the information and effectiveness of stimulated photon echo responses locking at different encoding information in the object laser pulses are investigated.

  8. Estimation of photoneutron intensities around radiotherapy linear accelerator 23-MV photon beam.

    PubMed

    Shweikani, R; Anjak, O

    2015-05-01

    CR-39 solid-state nuclear track detectors (SSNTDs) were used to study the variations of fast neutron relative intensities around a high-energy (23MV) linear accelerator (Varian 21EX) photon beam. The variations were determined on the patient plane at 0, 50, 100, 150 and 200cm from the isocenter of the photon beam. In addition, photoneutron intensities and distributions at isocenter level with field size of 40×40cm(2) at Source Axis Distance (SAD)=100cm around 23MV photon beam were also determined. The results showed that the photoneutron intensities decreased rapidly by increasing the distance from the center of the x-ray beam towards the periphery, for the open fields. PMID:25770858

  9. Clinical assessment of 252Californium neutron intracavitary brachytherapy using a two-channel Y applicator combined with external beam radiotherapy for endometrial cancer

    PubMed Central

    Zhou, Qian; Cheng Tang; Zhao, Ke-Wei; Xiong, Yan-Li; Chen, Shu; Xu, Wen-Jing; Lei, Xin

    2016-01-01

    OBJECTIVE: The aim of this study was to determine the efficacy of 252Californium neutron intracavitary brachytherapy using a two-channel Y applicator combined with external beam radiotherapy for the treatment of endometrial cancer. METHODS: Thirty-one patients with stage I–III endometrial cancer were recruited for this study. The stage I patients received only 252Californium neutron intracavitary brachytherapy with a two-channel applicator. The stage II and III patients received both 252Californium neutron intracavitary brachytherapy using a two-channel applicator and parallel-opposed whole pelvic radiotherapy. RESULTS: The five-year local control rate was 80.6% (25/31), the overall survival rate was 51.6% (16/31), and the disease-free survival rate was 54.8% (17/31). The incidence of serious late complications was 12.9% (4/31). CONCLUSIONS: 252Californium neutron intracavitary brachytherapy using a two-channel applicator combined with external beam radiotherapy was effective for treating endometrial cancer and the incidence of serious late complications related to this combination was within an acceptable range. PMID:26872078

  10. Tuning the defect mode in ternary photonic crystal with external voltage for designing a controllable optical filter

    NASA Astrophysics Data System (ADS)

    Jamshidi-Ghaleh, Kazem; Rashidi, Shiva; Vahedi, Ali

    2015-09-01

    In this work, behavior of defect mode in one-dimensional ternary photonic crystal (1DTPC) structure with arrangement of (MgF2/Ag/TiO2)5LiNbO3(TiO2/Ag/MgF2)5 was investigated under the applied external electric dc voltage. The defect layer is lithium niobate (LiNbO3), an electro-optical (EO) material whose refractive index is voltage-dependent with high EO coefficient. In comparison, magnesium fluoride (MgF2) and titanium dioxide (TiO2) layers have very low EO coefficients. A narrow localized defect mode with perfect transmittance was appeared inside the photonic band gap. Under applying the positive or negative biases, red shift and blue shift was observed in the defect mode, respectively. More than 120 nm tunability was obtained under externally applied voltage in the range of -200 V to 200 V. The physical interpretation is very simple. Change in optical path-length displaces the localized wavelength of the defect mode due to Bragg interface condition. The externally tunable localized mode can be employed in designing a controllable optical filter, one of the essential devices for new-generation all-optical integrated circuits.

  11. The dosimetric impact of different photon beam energy on RapidArc radiotherapy planning for cervix carcinoma

    PubMed Central

    Kumar, Lalit; Yadav, Girigesh; Raman, Kothanda; Bhushan, Manindra; Pal, Manoj

    2015-01-01

    The main purpose of this study is to know the effect of three different photon energies viz., 6, 10, and 15 mega voltage (MV) on RapidArc (RA) planning for deep-seated cervix tumor and to develop clinically acceptable RA plans with suitable photon energy. RA plans were generated for 6, 10, and 15 MV photon energies for twenty patients reported with cervix carcinoma. RA plans were evaluated in terms of planning target volume (PTV) coverage, dose to organs at risk (OARs), conformity index (CI), homogeneity index (HI), gradient measure, external volume index of dose distribution produced, total number of monitor units (MUs), nontumor integral dose (ID), and low dose volume of normal tissue. A two-sample paired t-test was performed to compare the dosimetric parameters of RA plans. Irrespective of photon energy used for RA planning, plans were dosimetrically similar in terms of PTV coverage, OARs sparing, CI and HI. The numbers of MUs were 13.4 ± 1.4% and 18.2 ± 1.5% higher and IDs were 2.7 ± 0.8% and 3.7 ± 0.9% higher in 6 MV plans in comparison to that in the 10 and 15 MV plans, respectively. V1Gy, V2Gy, V3Gy, and V4Gy were higher in 6 MV plans in comparison to that in 10 and 15 MV plans. Based on this study, 6 MV photon beam is a good choice for RA planning in case of cervix carcinoma, as it does not deliver additional exposure to patients caused by photoneutrons produced in high energy beams. PMID:26865756

  12. MO-G-BRE-01: A Real-Time Virtual Delivery System for Photon Radiotherapy Delivery Monitoring

    SciTech Connect

    Shi, F; Gu, X; Jiang, S; Jia, X; Graves, Y

    2014-06-15

    Purpose: Treatment delivery monitoring is important for radiotherapy, which enables catching dosimetric error at the earliest possible opportunity. This project develops a virtual delivery system to monitor the dose delivery process of photon radiotherapy in real-time using GPU-based Monte Carlo (MC) method. Methods: The simulation process consists of 3 parallel CPU threads. A thread T1 is responsible for communication with a linac, which acquires a set of linac status parameters, e.g. gantry angles, MLC configurations, and beam MUs every 20 ms. Since linac vendors currently do not offer interface to acquire data in real time, we mimic this process by fetching information from a linac dynalog file at the set frequency. Instantaneous beam fluence map (FM) is calculated. A FM buffer is also created in T1 and the instantaneous FM is accumulated to it. This process continues, until a ready signal is received from thread T2 on which an inhouse developed MC dose engine executes on GPU. At that moment, the accumulated FM is transferred to T2 for dose calculations, and the FM buffer in T1 is cleared. Once the calculation finishes, the resulting 3D dose distribution is directed to thread T3, which displays it in three orthogonal planes overlaid on the CT image for treatment monitoring. This process continues to monitor the 3D dose distribution in real-time. Results: An IMRT and a VMAT cases used in our patient-specific QA are studied. Maximum dose differences between our system and treatment planning system are 0.98% and 1.58% for the two cases, respectively. The average time per MC calculation is 0.1sec with <2% relative uncertainty. The update frequency of ∼10Hz is considered as real time. Conclusion: By embedding a GPU-based MC code in a novel data/work flow, it is possible to achieve real-time MC dose calculations to monitor delivery process.

  13. Lithographic wavelength control of an external cavity laser with a silicon photonic crystal cavity-based resonant reflector.

    PubMed

    Liles, Alexandros A; Debnath, Kapil; O'Faolain, Liam

    2016-03-01

    We report the experimental demonstration of a new design for external cavity hybrid lasers consisting of a III-V semiconductor optical amplifier (SOA) with fiber reflector and a photonic crystal (PhC)-based resonant reflector on SOI. The silicon reflector is composed of an SU8 polymer bus waveguide vertically coupled to a PhC cavity and provides a wavelength-selective optical feedback to the laser cavity. This device exhibits milliwatt-level output power and side-mode suppression ratios of more than 25 dB. PMID:26974073

  14. Projected Second Tumor Risk and Dose to Neurocognitive Structures After Proton Versus Photon Radiotherapy for Benign Meningioma

    SciTech Connect

    Arvold, Nils D.; Niemierko, Andrzej; Broussard, George P.; Adams, Judith; Fullerton, Barbara; Loeffler, Jay S.; Shih, Helen A.

    2012-07-15

    Purpose: To calculated projected second tumor rates and dose to organs at risk (OAR) in patients with benign intracranial meningioma (BM), according to dosimetric comparisons between proton radiotherapy (PRT) and photon radiotherapy (XRT) treatment plans. Methods and Materials: Ten patients with BM treated at Massachusetts General Hospital during 2006-2010 with PRT were replanned with XRT (intensity-modulated or three-dimensional conformal radiotherapy), optimizing dose to the tumor while sparing OAR. Total dose was 54 Gy in 1.8 Gy per fraction for all plans. We calculated equivalent uniform doses, normal tissue complication probabilities, and whole brain-based estimates of excess risk of radiation-associated intracranial second tumors. Results: Excess risk of second tumors was significantly lower among PRT compared with XRT plans (1.3 vs. 2.8 per 10,000 patients per year, p < 0.002). Mean equivalent uniform doses were lower among PRT plans for the whole brain (19.0 vs. 22.8 Gy, p < 0.0001), brainstem (23.8 vs. 35.2 Gy, p = 0.004), hippocampi (left, 13.5 vs. 25.6 Gy, p < 0.0001; right, 7.6 vs. 21.8 Gy, p = 0.001), temporal lobes (left, 25.8 vs. 34.6 Gy, p = 0.007; right, 25.8 vs. 32.9 Gy, p = 0.008), pituitary gland (29.2 vs. 37.0 Gy, p = 0.047), optic nerves (left, 28.5 vs. 33.8 Gy, p = 0.04; right, 25.1 vs. 31.1 Gy, p = 0.07), and cochleas (left, 12.2 vs. 15.8 Gy, p = 0.39; right,1.5 vs. 8.8 Gy, p = 0.01). Mean normal tissue complication probability was <1% for all structures and not significantly different between PRT and XRT plans. Conclusions: Compared with XRT, PRT for BM decreases the risk of RT-associated second tumors by half and delivers significantly lower doses to neurocognitive and critical structures of vision and hearing.

  15. Can All Centers Plan Intensity-Modulated Radiotherapy (IMRT) Effectively? An External Audit of Dosimetric Comparisons Between Three-Dimensional Conformal Radiotherapy and IMRT for Adjuvant Chemoradiation for Gastric Cancer

    SciTech Connect

    Chung, Hans T. Lee, Brian; Park, Eileen; Lu, Jiade J.; Xia Ping

    2008-07-15

    Purpose: To compare dosimetric endpoints between three-dimensional conformal radiotherapy (3D-CRT) and intensity-modulated radiotherapy (IMRT) at our center with limited IMRT experience, and to perform an external audit of the IMRT plans. Methods and Materials: Ten patients, who received adjuvant chemoradiation for gastric cancer, formed the study cohort. For standardization, the planning target volume (PTV) and organs at risk were recontoured with the assistance of a study protocol radiologic atlas. The cohort was replanned with CMS Xio to generate coplanar 3D-CRT and IMRT plans. All 10 datasets, including volumes but without the plans (i.e., blinded), were transmitted to an experienced center where IMRT plans were designed using Nomos Corvus (IMRT-C) and ADAC Pinnacle (IMRT-P). All IMRT plans were normalized to D95% receiving 45 Gy. Results: Intensity-modulated radiotherapy yielded higher PTV V45 (volume that receives {>=}45 Gy) (p < 0.001) than 3D-CRT. No difference in V20 was seen in the right (p = 0.9) and left (p 0.3) kidneys, but the liver mean dose (p < 0.001) was superior with IMRT. For the external audit, IMRT-C (p = 0.002) and IMRT-P (p < 0.001) achieved significantly lower left kidney V20 than IMRT, and IMRT-P (p < 0.001) achieved lower right kidney V20 than IMRT. The IMRT-C (p = 0.003) but not IMRT-P (p = 0.6) had lower liver mean doses than IMRT. Conclusions: At our institution with early IMRT experience, IMRT improved PTV dose coverage and liver doses but not kidney doses. An external audit of IMRT plans showed that an experienced center can yield superior IMRT plans.

  16. Intraoperative radiotherapy with low energy photons in recurrent colorectal cancer: a single centre retrospective study

    PubMed Central

    Skórzewska, Magdalena; Mielko, Jerzy; Kurylcio, Andrzej; Romanek, Jarosław

    2016-01-01

    Aim of the study Intraoperative radiotherapy (IORT) may improve outcome of surgical treatment of recurrent colorectal cancer (CRC). The aim of this study is to determine the feasibility, safety and long-term results of surgical treatment of recurrent CRC with orthovolt IORT. Material and methods Fifty-nine consecutive CRC patients with local recurrence (LR), undergoing surgery, were included in the retrospective analysis of prospectively collected data. The modified Wanebo classification was used to stage LR (Tr). Twenty-five (43%) patients received IORT using INTRABEAM® PRS 500. The complications were classified according to the Clavien-Dindo classification. Results There were 32 males and 27 females, with a median age of 63 years. Multi-visceral resections were performed in 37 (63%) patients. Median hospitalization time after surgery with IORT was 7 days. One (1.7%) in-hospital postoperative death was reported. Grade 3/4 postoperative complications were found in 11 (19%) patients. Intraoperative radiotherapy had no effect on the postoperative hospitalization time, morbidity and mortality. Median survival after R0 resection was 32 months. Complete resection (R0), no synchronous liver metastases (M0), and no lateral and posterior pelvic wall involvement, were significant predictors of improved survival. Stage of LR was found to be an independent prognostic factor in the multivariate analysis (p = 0.03); Cox regression model). In patients with LR stage < Tr5, a 3-year overall survival (OS) rate was 52%. Conclusions Combination of surgical resection and orthovolt IORT is a safe and feasible procedure that does not increase the risk of postoperative complications or prolongs the hospital stay. Despite aggressive surgery supported by IORT, the advanced stage of LR is a limiting factor of long-term survival. PMID:27095940

  17. Superficial dosimetry imaging based on Čerenkov emission for external beam radiotherapy with megavoltage x-ray beam

    PubMed Central

    Zhang, Rongxiao; Glaser, Adam K.; Gladstone, David J.; Fox, Colleen J.; Pogue, Brian W.

    2013-01-01

    results show there is good potential for real-time superficial dose monitoring. Dose imaging under normal ambient room lighting was validated, using gated detection and a breast phantom. Conclusions: This study indicates that Čerenkov emission imaging might provide a valuable way to superficial dosimetry imaging in real time for external beam radiotherapy with megavoltage x-ray beams. PMID:24089916

  18. Experimental assessment of out-of-field dose components in high energy electron beams used in external beam radiotherapy.

    PubMed

    M Alabdoaburas, Mohamad; Mege, Jean-Pierre; Chavaudra, Jean; Vũ Bezin, Jérémi; Veres, Atilla; De Vathaire, Florent; Lefkopoulos, Dimitri; Diallo, Ibrahima

    2015-01-01

    The purpose of this work was to experimentally investigate the out-of-field dose in a water phantom, with several high energy electron beams used in external beam radiotherapy (RT). The study was carried out for 6, 9, 12, and 18 MeV electron beams, on three different linear accelerators, each equipped with a specific applicator. Measurements were performed in a water phantom, at different depths, for different applicator sizes, and off-axis distances up to 70 cm from beam central axis (CAX). Thermoluminescent powder dosimeters (TLD-700) were used. For given cases, TLD measurements were compared to EBT3 films and parallel-plane ionization chamber measurements. Also, out-of-field doses at 10 cm depth, with and without applicator, were evaluated. With the Siemens applicators, a peak dose appears at about 12-15 cm out of the field edge, at 1 cm depth, for all field sizes and energies. For the Siemens Primus, with a 10 × 10 cm(²) applicator, this peak reaches 2.3%, 1%, 0.9% and 1.3% of the maximum central axis dose (Dmax) for 6, 9, 12 and 18 MeV electron beams, respectively. For the Siemens Oncor, with a 10 × 10 cm(²) applicator, this peak dose reaches 0.8%, 1%, 1.4%, and 1.6% of Dmax for 6, 9, 12, and 14 MeV, respectively, and these values increase with applicator size. For the Varian 2300C/D, the doses at 12.5 cm out of the field edge are 0.3%, 0.6%, 0.5%, and 1.1% of Dmax for 6, 9, 12, and 18 MeV, respectively, and increase with applicator size. No peak dose is evidenced for the Varian applicator for these energies. In summary, the out-of-field dose from electron beams increases with the beam energy and the applicator size, and decreases with the distance from the beam central axis and the depth in water. It also considerably depends on the applicator types. Our results can be of interest for the dose estimations delivered in healthy tissues outside the treatment field for the RT patient, as well as in studies exploring RT long-term effects. PMID:26699572

  19. Superficial dosimetry imaging based on Čerenkov emission for external beam radiotherapy with megavoltage x-ray beam

    SciTech Connect

    Zhang, Rongxiao; Glaser, Adam K.; Gladstone, David J.; Fox, Colleen J.; Pogue, Brian W.

    2013-10-15

    results show there is good potential for real-time superficial dose monitoring. Dose imaging under normal ambient room lighting was validated, using gated detection and a breast phantom.Conclusions: This study indicates that Čerenkov emission imaging might provide a valuable way to superficial dosimetry imaging in real time for external beam radiotherapy with megavoltage x-ray beams.

  20. External Beam Radiotherapy Followed by {sup 90}Y Ibritumomab Tiuxetan in Relapsed or Refractory Bulky Follicular Lymphoma

    SciTech Connect

    Burdick, Michael J.; Neumann, Donald; Pohlman, Brad; Reddy, Chandana A.; Tendulkar, Rahul D.; Macklis, Roger

    2011-03-15

    Purpose: We combined external beam radiotherapy (EBRT) with yttrium-90 ibritumomab tiuxetan ({sup 90}Y-IT) in an attempt to improve therapeutic response in patients with relapsed or refractory bulky follicular lymphoma (RRBFL). Methods and Materials: Between February 2006 and September 2007, 11 patients with RRBFL were treated with EBRT followed by {sup 90}Y-IT. Bulky disease (BD) was defined as >5 cm. EBRT was delivered to BD as 2,400 cGy in eight fractions using computed tomography (CT)-based planning. BD was contoured as the gross tumor volume. A planning margin of 1 to 2 cm was added depending on anatomical location. After recovery of complete blood counts (CBC), {sup 90}Y-IT was administered at a dose of 0.3 or 0.4 mCi/kg depending on platelet counts. Hematologic toxicity was monitored through weekly CBC. Response was measured by positron emission tomography/CT or CT 3-4 months after {sup 90}Y-IT. Results: Only 2 patients required prolonged breaks between EBRT and {sup 90}Y-IT. The median time after {sup 90}Y-IT for platelets to recover to >100,000/ml was 55 days (range, 41-128 days). Platelet counts for 1 patient, who had received 4 previous chemotherapy regimens, never reached 100,000/ml. The complete and overall responses to combined therapy as measured 3-4 months after {sup 90}Y-IT were 64%. No patients relapsed within the EBRT field. With a median follow-up of 36.1 months, 6 patients have relapsed, 2 of whom have died. Median progression-free survival was 17.5 months. Conclusions: In contrast to prior failure analysis data for RRBFL patients treated with {sup 90}Y-IT alone, a brief course of EBRT prevented relapse in sites of BD. EBRT used to pretreat bulky sites may improve clinical outcomes and potentially extend survival when combined with {sup 90}Y-IT.

  1. Outcomes of Patients With Non-Hodgkin's Lymphoma Treated With Bexxar With or Without External-Beam Radiotherapy

    SciTech Connect

    Smith, Kristy; Byer, Gracie; Morris, Christopher G.; Kirwan, Jessica M.; Lightsey, Judith; Mendenhall, Nancy P.; Hoppe, Bradford S.; Lynch, James

    2012-03-01

    Purpose: To compare the efficacy and toxicity of external-beam radiotherapy (EBRT) to sites of bulky lymphadenopathy in patients with chemotherapy-refractory low-grade non-Hodgkin's lymphoma (NHL) immediately before receiving Bexxar (tositumomab and {sup 131}I) vs. in patients receiving Bexxar alone for nonbulky disease. Methods and Materials: Nineteen patients with chemotherapy-refractory NHL were treated with Bexxar at our institution (University of Florida, Gainesville, FL) from 2005 to 2008. Seventeen patients had Grade 1-2 follicular lymphoma. Ten patients received a median of 20 Gy in 10 fractions to the areas of clinical involvement, immediately followed by Bexxar (EBRT + Bexxar); 9 patients received Bexxar alone. The median tumor sizes before EBRT + Bexxar and Bexxar alone were 4.8 cm and 3.3 cm, respectively. All 5 patients with a tumor diameter >5 cm were treated with EBRT + Bexxar. A univariate analysis of prognostic factors for progression-free survival (PFS) was performed. Results: The median follow-up was 2.3 years for all patients and 3.1 years for 12 patients alive at last follow-up. Of all patients, 79% had a partial or complete response; 4 of the 8 responders in the EBRT + Bexxar group achieved a durable response of over 2 years, including 3 of the 5 with tumors >5 cm. Three of 9 patients treated with Bexxar alone achieved a durable response over 2 years. Actuarial estimates of 3-year overall survival and PFS for EBRT + Bexxar and Bexxar alone were 69% and 38% and 62% and 33%, respectively. The median time to recurrence after EBRT + Bexxar and Bexxar alone was 9 months. Having fewer than 4 involved lymph-node regions was associated with superior PFS at 3 years (63% vs. 18%). There was no Grade 4 or 5 complications. Conclusions: Adding EBRT immediately before Bexxar produced PFS equivalent to that with Bexxar alone, despite bulkier disease. Hematologic toxicity was not worsened. EBRT combined with Bexxar adds a safe and effective therapeutic

  2. Instant-mix whole brain photon with neutron boost radiotherapy for malignant gliomas

    SciTech Connect

    Kolker, J.D.; Halpern, H.J.; Krishnasamy, S.; Brown, F.; Dohrmann, G.; Ferguson, L.; Hekmatpanah, J.; Mullan, J.; Wollman, R.; Blough, R. )

    1990-08-01

    From July 1985 through March 1987, 44 consecutive patients with supratentorial, nonmetastatic anaplastic astrocytoma (AA) and glioblastoma multiforme (GBM) were treated with whole brain photon irradiation with concomitant neutron boost at the University of Chicago. All patients had biopsy proven disease and surgery ranged from biopsy to total gross excision. Whole brain photon radiation was given at 1.5 Gy per fraction, 5 days weekly for a total dose of 45 Gy in 6 weeks. Neutron boost radiation was prescribed to a target minimum dose that included the pre-surgical CT tumor volume plus 1 cm margin. Neutrons were administered 5-20 minutes prior to photon radiation twice weekly and a total dose of 5.2 Gyn gamma was administered over 6 weeks. Median follow-up was 36 months. The median survival was 40.3 months for anaplastic astrocytoma (10 patients) and 11 months for glioblastoma multiforme (34 patients) and 12 months for the overall group. Variables that predicted longer median survival included histology (AA vs. GBM), age (less than or equal to 39 years vs. older), and extent of surgery (total gross or partial excision vs. biopsy) whereas tumor size and Karnofsky performance status did not have a significant influence. The median survival of the anaplastic astrocytoma group was better than expected compared to the RTOG 80-07 study (a dose-finding study of similar design to this study) and historical data. Reasons for this are discussed.

  3. Percentage of Cancer Volume in Biopsy Cores Is Prognostic for Prostate Cancer Death and Overall Survival in Patients Treated With Dose-Escalated External Beam Radiotherapy

    SciTech Connect

    Vance, Sean M.; Stenmark, Matthew H.; Blas, Kevin; Halverson, Schulyer; Hamstra, Daniel A.; Feng, Felix Y.

    2012-07-01

    Purpose: To investigate the prognostic utility of the percentage of cancer volume (PCV) in needle biopsy specimens for prostate cancer patients treated with dose-escalated external beam radiotherapy. Methods and Materials: The outcomes were analyzed for 599 men treated for localized prostate cancer with external beam radiotherapy to a minimal planning target volume dose of 75 Gy (range, 75-79.2). We assessed the effect of PCV and the pretreatment and treatment-related factors on the freedom from biochemical failure, freedom from metastasis, cause-specific survival, and overall survival. Results: The median number of biopsy cores was 7 (interquartile range, 6-12), median PCV was 10% (interquartile range, 2.5-25%), and median follow-up was 62 months. The PCV correlated with the National Comprehensive Cancer Network risk group and individual risk features, including T stage, prostate-specific antigen level, Gleason score, and percentage of positive biopsy cores. On log-rank analysis, the PCV stratified by quartile was prognostic for all endpoints, including overall survival. In addition, the PCV was a stronger prognostic factor than the percentage of positive biopsy cores when the two metrics were analyzed together. On multivariate analysis, the PCV predicted a worse outcome for all endpoints, including freedom from biochemical failure, (hazard ratio, 1.9; p = .0035), freedom from metastasis (hazard ratio, 1.7, p = .09), cause-specific survival (hazard ratio, 3.9, p = .014), and overall survival (hazard ratio, 1.8, p = .02). Conclusions: For patients treated with dose-escalated external beam radiotherapy, the volume of cancer in the biopsy specimen adds prognostic value for clinically relevant endpoints, particularly in intermediate- and high-risk patients. Although the PCV determination is more arduous than the percentage of positive biopsy cores, it provides superior risk stratification.

  4. Phase II Trial of Combined High-Dose-Rate Brachytherapy and External Beam Radiotherapy for Adenocarcinoma of the Prostate: Preliminary Results of RTOG 0321

    SciTech Connect

    Hsu, I-Chow; Bae, Kyounghwa; Shinohara, Katsuto; Pouliot, Jean; Purdy, James; Ibbott, Geoffrey; Speight, Joycelyn; Vigneault, Eric; Ivker, Robert M.D.; Sandler, Howard M.D.

    2010-11-01

    Purpose: To estimate the rate of late Grade 3 or greater genitourinary (GU) and gastrointestinal (GI) adverse events (AEs) after treatment with external beam radiotherapy and prostate high-dose-rate (HDR) brachytherapy. Methods and Materials: Each participating institution submitted computed tomography-based HDR brachytherapy dosimetry data electronically for credentialing and for each study patient. Patients with locally confined Stage T1c-T3b prostate cancer were eligible for the present study. All patients were treated with 45 Gy in 25 fractions using external beam radiotherapy and one HDR implant delivering 19 Gy in two fractions. All AEs were graded according to the Common Terminology Criteria for Adverse Events, version 3.0. Late GU/GI AEs were defined as those occurring >9 months from the start of the protocol treatment, in patients with {>=}18 months of potential follow-up. Results: A total of 129 patients from 14 institutions were enrolled in the present study. Of the 129 patients, 125 were eligible, and AE data were available for 112 patients at analysis. The pretreatment characteristics of the patients were as follows: Stage T1c-T2c, 91%; Stage T3a-T3b, 9%; prostate-specific antigen level {<=}10 ng/mL, 70%; prostate-specific antigen level >10 but {<=}20 ng/mL, 30%; and Gleason score 2-6, 10%; Gleason score 7, 72%; and Gleason score 8-10, 18%. At a median follow-up of 29.6 months, three acute and four late Grade 3 GU/GI AEs were reported. The estimated rate of late Grade 3-5 GU and GI AEs at 18 months was 2.56%. Conclusion: This is the first prospective, multi-institutional trial of computed tomography-based HDR brachytherapy and external beam radiotherapy. The technique and doses used in the present study resulted in acceptable levels of AEs.

  5. Single Photon Emission Computed Tomography-Based Three-Dimensional Conformal Radiotherapy for Hepatocellular Carcinoma With Portal Vein Tumor Thrombus

    SciTech Connect

    Shirai, Shintaro; Sato, Morio Suwa, Kazuhiro; Kishi, Kazushi; Shimono, Chigusa; Kawai, Nobuyuki; Tanihata, Hirohiko; Minamiguchi, Hiroki; Nakai, Motoki

    2009-03-01

    Purpose: To evaluate the safety and efficacy of three-dimensional conformal radiotherapy (3D-CRT) using single photon emission computed tomography (SPECT) in unresectable hepatocellular carcinoma (HCC) with portal vein tumor thrombus (PVTT). Methods and Materials: Patients with HCC with PVTT in the first branch and/or main trunk were selected for this study. The optimal beam directions for 3D-CRT were explored using a Tc-99m-galactosyl human serum albumin SPECT image for guidance. The SPECT image was classified as either wedge type or localized type. The clinical target volume to a total dose of 45 or 50 Gy per 18-20 fractions included the main tumor and PVTT in the wedge type and PVTT alone in the localized type. Results: Twenty-six patients were enrolled: 18 with wedge type and 8 with localized type. Mean tumor size was 7.1 cm (range, 4.4-12.3 cm). Clinical target volumes of wedge type vs. localized type were 111.2 cm{sup 3} vs. 48.4 cm{sup 3} (p = 0.010), respectively. Mean dose to normal liver and mean dose to functional liver were 1185 cGy and 988 cGy (p = 0.001) in wedge type and 1046 cGy and 1043 cGy (p = 0.658) in localized type, respectively. Despite an incidence of Child-Pugh B and C of 57.7%, no patients experienced radiation-induced liver disease. The progression of PVTT was inhibited, with an incidence of 92.2%; survival rates at 1 and 2 years were 44% and 30%, respectively. Conclusion: Single photon emission computed tomography-based 3D-CRT enables irradiation of both the main tumor and PVTT with low toxicity and promising survival.

  6. Phase II Study of High-Dose Photon/Proton Radiotherapy in the Management of Spine Sarcomas

    SciTech Connect

    DeLaney, Thomas F. Liebsch, Norbert J.; Pedlow, Francis X.; Adams, Judith; Dean, Susan; Yeap, Beow Y.; McManus, Patricia; Rosenberg, Andrew E.; Nielsen, G. Petur; Harmon, David C.; Spiro, Ira J.; Raskin, Kevin A.; Suit, Herman D.; Yoon, Sam S.; Hornicek, Francis J.

    2009-07-01

    Purpose: Radiotherapy (XRT) for spine sarcomas is constrained by spinal cord, nerve, and viscera tolerance. Negative surgical margins are uncommon; hence, doses of {>=}66 Gy are recommended. A Phase II clinical trial evaluated high-dose photon/proton XRT for spine sarcomas. Methods and Materials: Eligible patients had nonmetastatic, thoracic, lumbar, and/or sacral spine/paraspinal sarcomas. Treatment included pre- and/or postoperative photon/proton XRT with or without radical resection; patients with osteosarcoma and Ewing's sarcoma received chemotherapy. Shrinking fields delivered 50.4 cobalt Gray equivalent (Gy RBE) to subclinical disease, 70.2 Gy RBE to microscopic disease in the tumor bed, and 77.4 Gy RBE to gross disease at 1.8 Gy RBE qd. Doses were reduced for radiosensitive histologies, concurrent chemoradiation, or when diabetes or autoimmune disease present. Spinal cord dose was limited to 63/54 Gy RBE to surface/center. Intraoperative boost doses of 7.5 to 10 Gy could be given by dural plaque. Results: A total of 50 patients (29 chordoma, 14 chondrosarcoma, 7 other) underwent gross total (n = 25) or subtotal (n = 12) resection or biopsy (n = 13). With 48 month median follow-up, 5-year actuarial local control, recurrence-free survival, and overall survival are: 78%, 63%, and 87% respectively. Two of 36 (5.6%) patients treated for primary versus 7/14 (50%) for recurrent tumor developed local recurrence (p < 0.001). Five patients developed late radiation-associated complications; no myelopathy developed but three sacral neuropathies appeared after 77.12 to 77.4 Gy RBE. Conclusions: Local control with this treatment is high in patients radiated at the time of primary presentation. Spinal cord dose constraints appear to be safe. Sacral nerves receiving 77.12-77.4 Gy RBE are at risk for late toxicity.

  7. Validation of a new grid-based Boltzmann equation solver for dose calculation in radiotherapy with photon beams

    NASA Astrophysics Data System (ADS)

    Vassiliev, Oleg N.; Wareing, Todd A.; McGhee, John; Failla, Gregory; Salehpour, Mohammad R.; Mourtada, Firas

    2010-02-01

    A new grid-based Boltzmann equation solver, Acuros™, was developed specifically for performing accurate and rapid radiotherapy dose calculations. In this study we benchmarked its performance against Monte Carlo for 6 and 18 MV photon beams in heterogeneous media. Acuros solves the coupled Boltzmann transport equations for neutral and charged particles on a locally adaptive Cartesian grid. The Acuros solver is an optimized rewrite of the general purpose Attila© software, and for comparable accuracy levels, it is roughly an order of magnitude faster than Attila. Comparisons were made between Monte Carlo (EGSnrc) and Acuros for 6 and 18 MV photon beams impinging on a slab phantom comprising tissue, bone and lung materials. To provide an accurate reference solution, Monte Carlo simulations were run to a tight statistical uncertainty (σ ≈ 0.1%) and fine resolution (1-2 mm). Acuros results were output on a 2 mm cubic voxel grid encompassing the entire phantom. Comparisons were also made for a breast treatment plan on an anthropomorphic phantom. For the slab phantom in regions where the dose exceeded 10% of the maximum dose, agreement between Acuros and Monte Carlo was within 2% of the local dose or 1 mm distance to agreement. For the breast case, agreement was within 2% of local dose or 2 mm distance to agreement in 99.9% of voxels where the dose exceeded 10% of the prescription dose. Elsewhere, in low dose regions, agreement for all cases was within 1% of the maximum dose. Since all Acuros calculations required less than 5 min on a dual-core two-processor workstation, it is efficient enough for routine clinical use. Additionally, since Acuros calculation times are only weakly dependent on the number of beams, Acuros may ideally be suited to arc therapies, where current clinical algorithms may incur long calculation times.

  8. Photonic crystal-based flat lens integrated on a Bragg mirror for high-Q external cavity low noise laser.

    PubMed

    Seghilani, M S; Sellahi, M; Devautour, M; Lalanne, P; Sagnes, I; Beaudoin, G; Myara, M; Lafosse, X; Legratiet, L; Yang, J; Garnache, A

    2014-03-10

    We demonstrate a high reflectivity (> 99%), low-loss (< 0.1%) and aberrations-free (2% of λ rms phase fluctuations) concave Bragg mirror (20mm radius of curvature) integrating a photonic crystal with engineered spherical phase and amplitude transfer functions, based on a III-V semiconductors flat photonics technology. This mirror design is of high interest for highly coherent high power stable external cavity semiconductor lasers, exhibiting very low noise. We design the photonic crystal for operation in the pass band. The approach incorporates spatial, spectral (filter bandwidth= 5nm) and polarization filtering capabilities. Thanks to the mirror, a compact single mode TEM(00) 2mm-long air gap high finesse (cold cavity Q-factor 10(6) - 10(7)) stable laser cavity is demonstrated with a GaAs-based quantum-wells 1/2-VCSEL gain structure at 1μm. Excellent laser performances are obtained in single frequency operation: low threshold density of 2kW/cm(2) with high differential efficiency (21%). And high spatial, temporal and polarization coherence: TEM(00) beam close to diffraction limit, linear light polarization (> 60dB), Side Mode Suppression Ratio > 46dB, relative intensity noise at quantum limit (< -150dB) in 1MHz-84GHz radio frequency range, and a theoretical linewidth fundamental limit at 10 Hz (Q-factor ∼ 3.10(13)). PMID:24663933

  9. Monte Carlo photon beam modeling and commissioning for radiotherapy dose calculation algorithm.

    PubMed

    Toutaoui, A; Ait chikh, S; Khelassi-Toutaoui, N; Hattali, B

    2014-11-01

    The aim of the present work was a Monte Carlo verification of the Multi-grid superposition (MGS) dose calculation algorithm implemented in the CMS XiO (Elekta) treatment planning system and used to calculate the dose distribution produced by photon beams generated by the linear accelerator (linac) Siemens Primus. The BEAMnrc/DOSXYZnrc (EGSnrc package) Monte Carlo model of the linac head was used as a benchmark. In the first part of the work, the BEAMnrc was used for the commissioning of a 6 MV photon beam and to optimize the linac description to fit the experimental data. In the second part, the MGS dose distributions were compared with DOSXYZnrc using relative dose error comparison and γ-index analysis (2%/2 mm, 3%/3 mm), in different dosimetric test cases. Results show good agreement between simulated and calculated dose in homogeneous media for square and rectangular symmetric fields. The γ-index analysis confirmed that for most cases the MGS model and EGSnrc doses are within 3% or 3 mm. PMID:24947967

  10. Correlation Between Acute and Late Toxicity in 973 Prostate Cancer Patients Treated With Three-Dimensional Conformal External Beam Radiotherapy

    SciTech Connect

    Jereczek-Fossa, Barbara A.; Zerini, Dario; Fodor, Cristiana

    2010-09-01

    Purpose: To analyze the correlation between acute and late injury in 973 prostate cancer patients treated with radiotherapy and to evaluate the effect of patient-, tumor-, and treatment-related variables on toxicity. Methods and Materials: Of the 973 patients, 542 and 431 received definitive or postprostatectomy radiotherapy, respectively. Three-dimensional conformal radiotherapy included a six-field technique and two-dynamic arc therapy. Toxicity was classified according to the Radiation Therapy Oncology Group/European Organization for Research and Treatment of Cancer criteria. The correlation between acute and late toxicity (incidence and severity) was assessed. Results: Multivariate analysis showed that age {<=}65 years (p = .06) and use of the three-dimensional, six-field technique (p <.0001) correlated significantly with greater acute rectal toxicity. The three-dimensional, six-field technique (p = .0002), dose >70 Gy (p = .014), and radiotherapy duration (p = .05) correlated with greater acute urinary toxicity. Acute rectal toxicity (p <.0001) was the only factor that correlated with late rectal injury on multivariate analysis. Late urinary toxicity correlated with acute urinary events (p <.0001) and was inversely related to the use of salvage radiotherapy (p = .018). A highly significant correlation was found between the incidence of acute and late events for both rectal (p <.001) and urinary (p <.001) reactions. The severity of acute toxicity (Grade 2 or greater) was predictive for the severity of late toxicity for both rectal and urinary events (p <.001). Conclusion: The results of our study have shown that the risk of acute reactions depends on both patient-related (age) and treatment-related (dose, technique) factors. Acute toxicity was an independent significant predictor of late toxicity. These findings might help to predict and prevent late radiotherapy-induced complications.

  11. Multi-institutional clinical experience with the Calypso System in localization and continuous, real-time monitoring of the prostate gland during external radiotherapy

    SciTech Connect

    Kupelian, Patrick . E-mail: patrick.kupelian@orhs.org; Willoughby, Twyla; Mahadevan, Arul; Djemil, Toufik; Weinstein, Geoffrey; Jani, Shirish; Enke, Charles; Solberg, Timothy; Flores, Nicholas

    2007-03-15

    Purpose: To report the clinical experience with an electromagnetic treatment target positioning and continuous monitoring system in patients with localized prostate cancer receiving external beam radiotherapy. Methods and Materials: The Calypso System is a target positioning device that continuously monitors the location of three implanted electromagnetic transponders at a rate of 10 Hz. The system was used at five centers to position 41 patients over a full course of therapy. Electromagnetic positioning was compared to setup using skin marks and to stereoscopic X-ray localization of the transponders. Continuous monitoring was performed in 35 patients. Results: The difference between skin mark vs. the Calypso System alignment was found to be >5 mm in vector length in more than 75% of fractions. Comparisons between the Calypso System and X-ray localization showed good agreement. Qualitatively, the continuous motion was unpredictable and varied from persistent drift to transient rapid movements. Displacements {>=}3 and {>=}5 mm for cumulative durations of at least 30 s were observed during 41% and 15% of sessions. In individual patients, the number of fractions with displacements {>=}3 mm ranged from 3% to 87%; whereas the number of fractions with displacements {>=}5 mm ranged from 0% to 56%. Conclusion: The Calypso System is a clinically efficient and objective localization method for positioning prostate patients undergoing radiotherapy. Initial treatment setup can be performed rapidly, accurately, and objectively before radiation delivery. The extent and frequency of prostate motion during radiotherapy delivery can be easily monitored and used for motion management.

  12. Analysis of coupling between two-dimensional photonic crystal waveguide and external waveguide

    NASA Astrophysics Data System (ADS)

    Miyai, Eiji; Okano, Makoto; Mochizuki, Masamitsu; Noda, Susumu

    2002-11-01

    Coupling between conventional wire waveguide and two-dimensional photonic crystal waveguide was analyzed by means of a three-dimensional finite difference time domain method. We evaluated the transmittance corresponding to the coupling efficiency between two waveguides. By using SiO2 clad below the wire and setting the width of the wire to be an appropriate value, we obtained single mode guiding and a coupling efficiency over 80% for the wave length around 1.55 mum.

  13. Monte Carlo calculation of dose rate conversion factors for external exposure to photon emitters in soil.

    PubMed

    Clouvas, A; Xanthos, S; Antonopoulos-Domis, M; Silva, J

    2000-03-01

    The dose rate conversion factors D(CF) (absorbed dose rate in air per unit activity per unit of soil mass, nGy h(-1) per Bq kg(-1)) are calculated 1 m above ground for photon emitters of natural radionuclides uniformly distributed in the soil. Three Monte Carlo codes are used: 1) The MCNP code of Los Alamos; 2) The GEANT code of CERN; and 3) a Monte Carlo code developed in the Nuclear Technology Laboratory of the Aristotle University of Thessaloniki. The accuracy of the Monte Carlo results is tested by the comparison of the unscattered flux obtained by the three Monte Carlo codes with an independent straightforward calculation. All codes and particularly the MCNP calculate accurately the absorbed dose rate in air due to the unscattered radiation. For the total radiation (unscattered plus scattered) the D(CF) values calculated from the three codes are in very good agreement between them. The comparison between these results and the results deduced previously by other authors indicates a good agreement (less than 15% of difference) for photon energies above 1,500 keV. Antithetically, the agreement is not as good (difference of 20-30%) for the low energy photons. PMID:10688452

  14. Improving anatomical mapping of complexly deformed anatomy for external beam radiotherapy and brachytherapy dose accumulation in cervical cancer

    SciTech Connect

    Vásquez Osorio, Eliana M. Kolkman-Deurloo, Inger-Karine K.; Schuring-Pereira, Monica; Zolnay, András; Heijmen, Ben J. M.; Hoogeman, Mischa S.

    2015-01-15

    Purpose: In the treatment of cervical cancer, large anatomical deformations, caused by, e.g., tumor shrinkage, bladder and rectum filling changes, organ sliding, and the presence of the brachytherapy (BT) applicator, prohibit the accumulation of external beam radiotherapy (EBRT) and BT dose distributions. This work proposes a structure-wise registration with vector field integration (SW+VF) to map the largely deformed anatomies between EBRT and BT, paving the way for 3D dose accumulation between EBRT and BT. Methods: T2w-MRIs acquired before EBRT and as a part of the MRI-guided BT procedure for 12 cervical cancer patients, along with the manual delineations of the bladder, cervix-uterus, and rectum-sigmoid, were used for this study. A rigid transformation was used to align the bony anatomy in the MRIs. The proposed SW+VF method starts by automatically segmenting features in the area surrounding the delineated organs. Then, each organ and feature pair is registered independently using a feature-based nonrigid registration algorithm developed in-house. Additionally, a background transformation is calculated to account for areas far from all organs and features. In order to obtain one transformation that can be used for dose accumulation, the organ-based, feature-based, and the background transformations are combined into one vector field using a weighted sum, where the contribution of each transformation can be directly controlled by its extent of influence (scope size). The optimal scope sizes for organ-based and feature-based transformations were found by an exhaustive analysis. The anatomical correctness of the mapping was independently validated by measuring the residual distances after transformation for delineated structures inside the cervix-uterus (inner anatomical correctness), and for anatomical landmarks outside the organs in the surrounding region (outer anatomical correctness). The results of the proposed method were compared with the results of the

  15. Intraoperative electron boost radiation followed by moderate doses of external beam radiotherapy in limb-sparing treatment of patients with extremity soft-tissue sarcoma

    SciTech Connect

    Oertel, Susanne; Treiber, Martina; Zahlten-Hinguranage, Angelika; Eichin, Steffen; Roeder, Falk; Funk, Angela; Hensley, Frank W.; Timke, Carmen; Niethammer, Andreas G.; Huber, Peter E.; Weitz, Juergen; Eble, Micheal J.; Buchler, Markus W.; Bernd, Ludger; Debus, Juergen; Krempien, Robert C. . E-mail: robert_krempien@med.uni-heidelberg.de

    2006-04-01

    Purpose: To analyze long-term prognosis and morbidity after limb-sparing treatment of patients with extremity soft-tissue sarcoma, with intraoperative electron boost radiotherapy (IOERT) followed by a moderate dose of external beam radiotherapy (EBRT). Methods and Materials: A total of 153 patients who were treated in a single center from 1991 to 2004 were evaluated. Median IOERT dose was 15 Gy, mean EBRT dose 43 Gy (range, 40-50.4 Gy) in conventional fractionation (1.8-2 Gy). Median duration of follow-up was 33 months. Acute toxicity was assessed with Common Toxicity Criteria; late toxic effects were scored according to European Organization for Research and Treatment of Cancer/Radiation Therapy Oncology Group criteria. Results: Five-year overall survival and 5-year local control rates were 77% and 78%, respectively. Whereas tumor size, patient age, and EBRT dose did not significantly affect outcome, resection status and grading were significant for survival; resection status and IOERT dose were significant for local control. Extremity salvage until death or time of follow-up was achieved in 90% of our patients, 86% of whom showed excellent limb function without impairment in activities of daily life. Acute toxicity Grade 2-4 was observed in 23% and late toxicity Grade 2-4 in 17% of patients. Conclusions: Treatment with IOERT combined with moderate doses of external beam irradiation yields high local control and extremity preservation rates in resected extremity soft-tissue sarcoma.

  16. Health-Related Quality of Life 2 Years After Treatment With Radical Prostatectomy, Prostate Brachytherapy, or External Beam Radiotherapy in Patients With Clinically Localized Prostate Cancer

    SciTech Connect

    Ferrer, Montserrat Suarez, Jose Francisco; Guedea, Ferran; Fernandez, Pablo; Macias, Victor; Marino, Alfonso; Hervas, Asuncion; Herruzo, Ismael; Ortiz, Maria Jose; Villavicencio, Humberto; Craven-Bratle, Jordi; Garin, Olatz; Aguilo, Ferran

    2008-10-01

    Purpose: To compare treatment impact on health-related quality of life (HRQL) in patients with localized prostate cancer, from before treatment to 2 years after the intervention. Methods and Materials: This was a longitudinal, prospective study of 614 patients with localized prostate cancer treated with radical prostatectomy (134), three-dimensional external conformal radiotherapy (205), and brachytherapy (275). The HRQL questionnaires administered before and after treatment (months 1, 3, 6, 12, and 24) were the Medical Outcomes Study 36-Item Short Form, the Functional Assessment of Cancer Therapy (General and Prostate Specific), the Expanded Prostate Cancer Index Composite (EPIC), and the American Urological Association Symptom Index. Differences between groups were tested by analysis of variance and within-group changes by univariate repeated-measures analysis of variance. Generalized estimating equations (GEE) models were constructed to assess between-group differences in HRQL at 2 years of follow-up after adjusting for clinical variables. Results: In each treatment group, HRQL initially deteriorated after treatment with subsequent partial recovery. However, some dimension scores were still significantly lower after 2 years of treatment. The GEE models showed that, compared with the brachytherapy group, radical prostatectomy patients had worse EPIC sexual summary and urinary incontinence scores (-20.4 and -14.1; p < 0.001), and external radiotherapy patients had worse EPIC bowel, sexual, and hormonal summary scores (-3.55, -5.24, and -1.94; p < 0.05). Prostatectomy patients had significantly better EPIC urinary irritation scores than brachytherapy patients (+4.16; p < 0.001). Conclusions: Relevant differences between treatment groups persisted after 2 years of follow-up. Radical prostatectomy had a considerable negative effect on sexual functioning and urinary continence. Three-dimensional conformal radiotherapy had a moderate negative impact on bowel

  17. Predictors of Long-Term Toxicity Using Three-Dimensional Conformal External Beam Radiotherapy to Deliver Accelerated Partial Breast Irradiation

    SciTech Connect

    Shaitelman, Simona F.; Kim, Leonard H.; Grills, Inga S.; Chen, Peter Y.; Ye Hong; Kestin, Larry L.; Yan Di; Vicini, Frank A.

    2011-11-01

    Purpose: We analyzed variables associated with long-term toxicity using three-dimensional conformal external beam radiation therapy (3D-CRT) to deliver accelerated partial breast irradiation. Methods and Materials: One hundred patients treated with 3D-CRT accelerated partial breast irradiation were evaluated using Common Terminology Criteria for Adverse Events version 4.0 scale. Cosmesis was scored using Harvard criteria. Multiple dosimetric and volumetric parameters were analyzed for their association with worst and last (W/L) toxicity outcomes. Results: Sixty-two patients had a minimum of 36 months of toxicity follow-up (median follow-up, 4.8 years). The W/L incidence of poor-fair cosmesis, any telangiectasia, and grade {>=}2 induration, volume reduction, and pain were 16.4%/11.5%, 24.2%/14.5%, 16.1%/9.7%, 17.7%/12.9%, and 11.3%/3.2%, respectively. Only the incidence of any telangiectasia was found to be predicted by any dosimetric parameter, with the absolute breast volume receiving 5% to 50% of the prescription dose (192.5 cGy-1925 cGy) being significant. No associations with maximum dose, volumes of lumpectomy cavity, breast, modified planning target volume, and PTV, dose homogeneity index, number of fields, and photon energy used were identified with any of the aforementioned toxicities. Non-upper outer quadrant location was associated with grade {>=}2 volume reduction (p = 0.02 W/p = 0.04 L). A small cavity-to-skin distance was associated with a grade {>=}2 induration (p = 0.03 W/p = 0.01 L), a borderline significant association with grade {>=}2 volume reduction (p = 0.06 W/p = 0.06 L) and poor-fair cosmesis (p = 0.08 W/p = 0.09 L), with threshold distances ranging from 5 to 8 mm. Conclusions: No dose--volume relationships associated with long-term toxicity were identified in this large patient cohort with extended follow-up. Cosmetic results were good-to-excellent in 88% of patients at 5 years.

  18. Comparison of Monte Carlo collimator transport methods for photon treatment planning in radiotherapy

    SciTech Connect

    Schmidhalter, D.; Manser, P.; Frei, D.; Volken, W.; Fix, M. K.

    2010-02-15

    Purpose: The aim of this work was a Monte Carlo (MC) based investigation of the impact of different radiation transport methods in collimators of a linear accelerator on photon beam characteristics, dose distributions, and efficiency. Thereby it is investigated if it is possible to use different simplifications in the radiation transport for some clinical situations in order to save calculation time. Methods: Within the Swiss Monte Carlo Plan, a GUI-based framework for photon MC treatment planning, different MC methods are available for the radiation transport through the collimators [secondary jaws and multileaf collimator (MLC)]: EGSnrc (reference), VMC++, and Pin (an in-house developed MC code). Additional nonfull transport methods were implemented in order to provide different complexity levels for the MC simulation: Considering collimator attenuation only, considering Compton scatter only or just the firstCompton process, and considering the collimators as totally absorbing. Furthermore, either a simple or an exact geometry of the collimators can be selected for the absorbing or attenuation method. Phasespaces directly above and dose distributions in a water phantom are analyzed for academic and clinical treatment fields using 6 and 15 MV beams, including intensity modulated radiation therapy with dynamic MLC. Results: For all MC transport methods, differences in the radial mean energy and radial energy fluence are within 1% inside the geometric field. Below the collimators, the energy fluence is underestimated for nonfull MC transport methods ranging from 5% for Compton to 100% for Absorbing. Gamma analysis using EGSnrc calculated doses as reference shows that the percentage of voxels fulfilling a 1% /1 mm criterion is at least 98% when using VMC++, Compton, or firstCompton transport methods. When using the methods Pin, Transmission, Flat-Transmission, Flat-Absorbing or Absorbing, the mean value of points fulfilling this criterion over all tested cases is 97

  19. PSA nadir predicts biochemical and distant failures after external beam radiotherapy for prostate cancer: A multi-institutional analysis

    SciTech Connect

    Ray, Michael E. . E-mail: mray@umich.edu; Thames, Howard D.; Levy, Larry B.; Horwitz, Eric M.; Kupelian, Patrick A.; Martinez, Alvaro A.; Michalski, Jeff M.; Pisansky, Thomas M.; Shipley, William U.; Zelefsky, Michael J.; Zietman, Anthony L.; Kuban, Deborah A.

    2006-03-15

    Purpose: To determine the significance of prostate-specific antigen (PSA) nadir (nPSA) and the time to nPSA (T{sub nPSA}) in predicting biochemical or clinical disease-free survival (PSA-DFS) and distant metastasis-free survival (DMFS) in patients treated with definitive external beam radiotherapy (RT) for clinical Stage T1b-T2 prostate cancer. Methods and Materials: Nine participating institutions submitted data on 4839 patients treated between 1986 and 1995 for Stage T1b-T2cN0-NxM0 prostate cancer. All patients were treated definitively with RT alone to doses {>=}60 Gy, without neoadjuvant or planned adjuvant androgen suppression. A total of 4833 patients with a median follow-up of 6.3 years met the criteria for analysis. Two endpoints were considered: (1) PSA-DFS, defined as freedom from PSA failure (American Society for Therapeutic Radiology and Oncology definition), initiation of androgen suppression after completion of RT, or documented local or distant failure; and (2) DMFS, defined as freedom from clinically apparent distant failure. In patients with failure, nPSA was defined as the lowest PSA measurement before any failure. In patients without failure, nPSA was the lowest PSA measurement during the entire follow-up period. T{sub nPSA} was calculated from the completion of RT to the nPSA date. Results: A greater nPSA level and shorter T{sub nPSA} were associated with decreased PSA-DFS and DMFS in all patients and in all risk categories (low [Stage T1b, T1c, or T2a, Gleason score {<=}6, and PSA level {<=}10 ng/mL], intermediate [Stage T1b, T1c, or T2a, Gleason score {<=}6, and PSA level >10 but {<=}20 ng/mL, or Stage T2b or T2c, Gleason score {<=}6, and PSA level {<=}20 ng/mL, or Gleason score 7 and PSA level {<=}20 ng/mL], and high [Gleason score 8-10 or PSA level >20 ng/mL]), regardless of RT dose. The 8-year PSA-DFS and DMFS rate for patients with nPSA <0.5 ng/mL was 75% and 97%; nPSA {>=}0.5 but <1.0 ng/mL, 52% and 96%; nPSA {>=}1.0 but <2.0 ng/mL, 40

  20. Freeform three-dimensional embedded polymer waveguides enabled by external-diffusion assisted two-photon lithography.

    PubMed

    Duc Nguyen, Ho Hoai; Hollenbach, Uwe; Ostrzinski, Ute; Pfeiffer, Karl; Hengsbach, Stefan; Mohr, Juergen

    2016-03-10

    This paper introduces a unique method to fabricate free-form symmetrical three-dimensional single-mode waveguides embedded in a newly developed photopolymer. The fabrication process requires only one layer of a single material by combining two-photon lithography and external monomer diffusion resulting in a high refractive index contrast of 0.013. The cured material exhibits high chemical and thermal stability. Transmission loss of 0.37  dB/cm at 850 nm is achieved. Due to the fact that waveguide arrays are produced with high density, this technique could pave the way for three-dimensional optical interconnects at the board level with high complexity and bandwidth density. PMID:26974781

  1. Review of ultrasound image guidance in external beam radiotherapy: I. Treatment planning and inter-fraction motion management.

    PubMed

    Fontanarosa, Davide; van der Meer, Skadi; Bamber, Jeffrey; Harris, Emma; O'Shea, Tuathan; Verhaegen, Frank

    2015-02-01

    In modern radiotherapy, verification of the treatment to ensure the target receives the prescribed dose and normal tissues are optimally spared has become essential. Several forms of image guidance are available for this purpose. The most commonly used forms of image guidance are based on kilovolt or megavolt x-ray imaging. Image guidance can also be performed with non-harmful ultrasound (US) waves. This increasingly used technique has the potential to offer both anatomical and functional information.This review presents an overview of the historical and current use of two-dimensional and three-dimensional US imaging for treatment verification in radiotherapy. The US technology and the implementation in the radiotherapy workflow are described. The use of US guidance in the treatment planning process is discussed. The role of US technology in inter-fraction motion monitoring and management is explained, and clinical studies of applications in areas such as the pelvis, abdomen and breast are reviewed. A companion review paper (O'Shea et al 2015 Phys. Med. Biol. submitted) will extensively discuss the use of US imaging for intra-fraction motion quantification and novel applications of US technology to RT. PMID:25592664

  2. Review of ultrasound image guidance in external beam radiotherapy: I. Treatment planning and inter-fraction motion management

    NASA Astrophysics Data System (ADS)

    Fontanarosa, Davide; van der Meer, Skadi; Bamber, Jeffrey; Harris, Emma; O'Shea, Tuathan; Verhaegen, Frank

    2015-02-01

    In modern radiotherapy, verification of the treatment to ensure the target receives the prescribed dose and normal tissues are optimally spared has become essential. Several forms of image guidance are available for this purpose. The most commonly used forms of image guidance are based on kilovolt or megavolt x-ray imaging. Image guidance can also be performed with non-harmful ultrasound (US) waves. This increasingly used technique has the potential to offer both anatomical and functional information. This review presents an overview of the historical and current use of two-dimensional and three-dimensional US imaging for treatment verification in radiotherapy. The US technology and the implementation in the radiotherapy workflow are described. The use of US guidance in the treatment planning process is discussed. The role of US technology in inter-fraction motion monitoring and management is explained, and clinical studies of applications in areas such as the pelvis, abdomen and breast are reviewed. A companion review paper (O’Shea et al 2015 Phys. Med. Biol. submitted) will extensively discuss the use of US imaging for intra-fraction motion quantification and novel applications of US technology to RT.

  3. Diffuse neutrino intensity from the inner jets of active galactic nuclei: Impacts of external photon fields and the blazar sequence

    NASA Astrophysics Data System (ADS)

    Murase, Kohta; Inoue, Yoshiyuki; Dermer, Charles D.

    2014-07-01

    We study high-energy neutrino production in inner jets of radio-loud active galactic nuclei (AGN), taking into account effects of external photon fields and the blazar sequence. We show that the resulting diffuse neutrino intensity is dominated by quasar-hosted blazars, in particular, flat spectrum radio quasars, and that PeV-EeV neutrino production due to photohadronic interactions with broadline and dust radiation is unavoidable if the AGN inner jets are ultrahigh-energy cosmic-ray (UHECR) sources. Their neutrino spectrum has a cutoff feature around PeV energies since target photons are due to Lyα emission. Because of infrared photons provided by the dust torus, neutrino spectra above PeV energies are too hard to be consistent with the IceCube data unless the proton spectral index is steeper than 2.5, or the maximum proton energy is ≲100 PeV. Thus, the simple model has difficulty in explaining the IceCube data. For the cumulative neutrino intensity from blazars to exceed ˜10-8 GeV cm-2 s-1 sr-1, their local cosmic-ray energy generation rate would be ˜10-100 times larger than the local UHECR emissivity but is comparable to the averaged γ-ray blazar emissivity. Interestingly, future detectors such as the Askaryan Radio Array can detect ˜0.1-1 EeV neutrinos even in more conservative cases, allowing us to indirectly test the hypothesis that UHECRs are produced in the inner jets. We find that the diffuse neutrino intensity from radio-loud AGN is dominated by blazars with γ-ray luminosity of ≳1048 erg s-1, and the arrival directions of their ˜1-100 PeV neutrinos correlate with the luminous blazars detected by Fermi.

  4. Optimised geometry to calculate dose rate conversion coefficient for external exposure to photons.

    PubMed

    Askri, B; Manai, K; Trabelsi, A; Baccari, B

    2008-01-01

    A single-parameter geometry to describe soil is achieved for Monte Carlo calculation of absorbed dose rate in air for photon emitters from natural radionuclides. This optimised geometry based on physical assumptions consists of the soil part whose emitted radiation has a given minimum probability to reach the detector. This geometry was implemented in Geant4 toolkit and a significant reduction in computation time was achieved. Simulation tests have shown that for soil represented by a cylinder of 40 m radius and 1 m deep, >98% of the calculated dose rate conversion coefficients in air at 1 m above the ground is generated by only 6% of the soil volume in the case of uniform distribution of radioactivity, and >99.2% of the calculated dose rate for an exponential distribution. When the soil is represented by the entire optimised geometry, 99% of the conversion coefficients values are reached for a soil depth of 1 m and 100% for that of approximately 2 m. PMID:17959610

  5. Clinical results of external beam radiotherapy alone with a concomitant boost program or with conventional fractionation for cervical cancer patients who did not receive intracavitary brachytherapy

    PubMed Central

    Matsuura, Kanji; Okabe, Tomoyuki; Fujita, Kazushi; Tanimoto, Hirotoshi; Akagi, Yukio; Kagemoto, Masayuki

    2012-01-01

    A combination of external beam radiotherapy (EBRT) and intracavitary brachytherapy (ICBT) is well established as the standard radical radiotherapy (RT) for cervical cancer. However, it is sometimes necessary to perform EBRT alone for patients where ICBT is not feasible. For these patients, we initiated EBRT alone with three-dimensional conformal radiotherapy (3DCRT). The purpose of this study is to evaluate the results of EBRT alone without ICBT for patients with cervical cancer. Sixteen patients were treated with EBRT alone between 2002 and 2009. There were three stage IIB, six stage IIIB and seven patients with stage IVA disease. A total of 10 patients were treated with a median dose of 66 Gy with a median overall treatment time (OTT) of 40 days delivered by a concomitant boost (CCB), and a median dose of 60 Gy with a median OTT of 47 days was administered for six patients by conventional fractionation (CF). The 3-year overall survival (OAS) and local control (LC) rates were 43.8% and 75.0%, respectively. The 3-year LC rate was 90.0% for the CCB group, 50.0% for the CF group (P = 0.0692); 100% for OTT ≤42 days, 42.9% for OTT ≥43 days (P = 0.0095). No severe acute and late adverse effects were encountered for any of the patients. These outcomes suggest that EBRT with a CCB program may be a promising radical treatment for cervical cancer that provides better LC with minimal complications, especially in cases where ICBT cannot be performed. PMID:22859563

  6. Successful delivery of adjuvant external beam radiotherapy for ependymoma in a patient with Ondine׳s curse.

    PubMed

    Choi, Mehee; Thoma, Miranda; Tolekidis, George; Byrne, Richard W; Diaz, Aidnag Z

    2015-01-01

    Ondine׳s curse is a rare, potentially life-threatening disorder characterized by loss of automatic breathing during sleep and preserved voluntary breathing. It is seldom encountered in the radiotherapy clinic but can pose significant technical challenges and safety concerns in the delivery of a prescribed radiation course. We report a unique case of successful delivery of radiotherapy for ependymoma in a patient with Ondine׳s curse. A 53-year-old gentleman presented with vertigo when lying down. Brain magnetic resonance imaging revealed an enhancing mass in the floor of the fourth ventricle. He underwent maximal safe resection. Pathology revealed ependymoma. The patient was referred for radiotherapy. Computed tomography simulation was performed in supine position with 3-point thermoplastic mask immobilization. Sequential TomoTherapy plans were developed. At first scheduled treatment, shortly after mask placement, his arms went limp and he was unresponsive. Vitals showed oxygen saturation 83%, pulse 127, and blood pressure 172/97mmHg. He was diagnosed with Ondine׳s curse thought secondary to previous brainstem damage; the combination of lying flat and pressure from the mask was causing him to go into respiratory arrest. As supine positioning did not seem clinically advisable, he was simulated in prone position. A RapidArc plan and a back-up conformal plan were developed. Prescriptions were modified to meet conservative organs-at-risk constraints. Several strategies were used to minimize uncertainties in set-up reproducibility associated with prone positioning. He tolerated prone RapidArc treatments well. The report highlights the importance of applying practical patient safety and treatment planning/delivery strategies in the management of this challenging case. PMID:26087849

  7. Pretreatment Endorectal Magnetic Resonance Imaging and Magnetic Resonance Spectroscopic Imaging Features of Prostate Cancer as Predictors of Response to External Beam Radiotherapy

    SciTech Connect

    Joseph, Tim; McKenna, David A.; Westphalen, Antonio C.; Coakley, Fergus V. Zhao Shoujun; Lu Ying; Hsu, I.-C.; Roach, Mack; Kurhanewicz, John

    2009-03-01

    Purpose: To evaluate whether pretreatment combined endorectal magnetic resonance imaging (MRI) and magnetic resonance spectroscopic imaging (MRSI) findings are predictive of outcome in patients who undergo external beam radiotherapy for prostate cancer. Methods and Materials: We retrospectively identified 67 men with biopsy-proven prostate cancer who underwent combined endorectal MRI and MRSI at our institution between January 1998 and October 2003 before whole-pelvis external beam radiotherapy. A single reader recorded tumor presence, stage, and metabolic abnormality at combined MRI and MRSI. Kaplan-Meier survival and Cox univariate and multivariate analyses explored the relationship between clinical and imaging variables and outcome, using biochemical or metastatic failure as endpoints. Results: After a mean follow-up of 44 months (range, 3-96), 6 patients developed both metastatic and biochemical failure, with an additional 13 patients developing biochemical failure alone. Multivariate Cox analysis demonstrated that the only independent predictor of biochemical failure was the volume of malignant metabolism on MRSI (hazard ratio [HR] 1.63, 95% confidence interval [CI] 1.29-2.06; p < 0.0001). The two independent predictors of metastatic failure were MRI tumor size (HR 1.34, 95% CI 1.03-1.73; p = 0.028) and the finding of seminal vesicle invasion on MRI (HR 28.05, 95% CI 3.96-198.67; p = 0.0008). Conclusions: In multivariate analysis, MRI and MRSI findings before EBRT in patients with prostate cancer are more accurate independent predictors of outcome than clinical variables, and in particular, the findings of seminal vesicle invasion and extensive tumor predict a worse prognosis.

  8. Experimental method of in-vivo dosimetry without build-up device on the skin for external beam radiotherapy

    NASA Astrophysics Data System (ADS)

    Jeon, Hosang; Nam, Jiho; Lee, Jayoung; Park, Dahl; Baek, Cheol-Ha; Kim, Wontaek; Ki, Yongkan; Kim, Dongwon

    2015-06-01

    Accurate dose delivery is crucial to the success of modern radiotherapy. To evaluate the dose actually delivered to patients, in-vivo dosimetry (IVD) is generally performed during radiotherapy to measure the entrance doses. In IVD, a build-up device should be placed on top of an in-vivo dosimeter to satisfy the electron equilibrium condition. However, a build-up device made of tissue-equivalent material or metal may perturb dose delivery to a patient, and requires an additional laborious and time-consuming process. We developed a novel IVD method using a look-up table of conversion ratios instead of a build-up device. We validated this method through a monte-carlo simulation and 31 clinical trials. The mean error of clinical IVD is 3.17% (standard deviation: 2.58%), which is comparable to that of conventional IVD methods. Moreover, the required time was greatly reduced so that the efficiency of IVD could be improved for both patients and therapists.

  9. Poster — Thur Eve — 35: The impact of intensity- and energy-modulated photon radiotherapy (XMRT) optimization on a variety of organ geometries

    SciTech Connect

    McGeachy, P.; Villarreal-Barajas, J. E.; Khan, R.; Zinchenko, Y.

    2014-08-15

    We previously reported on a novel, modulated in both energy and intensity; photon radiotherapy (XMRT) optimization technique. The purpose of this investigation was to test this XMRT optimization against conventional intensity modulated radiotherapy (IMRT) optimization on four different organ test geometries. All geometries mimicked clinically relevant scenarios. Both IMRT and XMRT were based on a linear programming approach where the objective function was the mean dose to healthy organs and organ-specific linear dose-point constraints were used. For IMRT, the beam energy was fixed to 6 MV while XMRT optimized in terms of both 6 and 18 MV beams. All plans consisted of a seven beam coplanar arrangement. All organ geometries were contoured on a 25cm diameter cylindrical water phantom in open source radiotherapy research software known as CERR. Solutions for both IMRT and XMRT were obtained for each geometry using a numerical solver Gurobi. Analyzing the quality of the solutions was done by comparing dose distributions and dose volume histograms calculated using CERR. For all four geometries, IMRT and XMRT solutions were comparable in terms of target coverage. For two of the geometries, IMRT provided an advantage in terms of reduced dose to the healthy structures. XMRT showed improved dose reduction to healthy organs for one geometry and a comparable dose distribution to IMRT for the remaining geometry. The inability to exploit the benefits of using multiple energies may be attributed to limited water phantom diameter and having the majority of the organs in close proximity to the transverse axis.

  10. Local Tumor Control, Visual Acuity, and Survival After Hypofractionated Stereotactic Photon Radiotherapy of Choroidal Melanoma in 212 Patients Treated Between 1997 and 2007

    SciTech Connect

    Dunavoelgyi, Roman; Dieckmann, Karin; Gleiss, Andreas; Sacu, Stefan; Kircher, Karl; Georgopoulos, Michael; Georg, Dietmar; Zehetmayer, Martin; Poetter, Richard

    2011-09-01

    Purpose: To evaluate long-term local tumor control, visual acuity, and survival after hypofractionated linear accelerator-based stereotactic photon radiotherapy in patients with choroidal melanoma. Methods and Materials: Between 1997 and 2007, 212 patients with choroidal melanoma unsuitable for ruthenium-106 brachytherapy or local resection were treated stereotactically at a linear accelerator with 6-MV photon beams at the Medical University of Vienna in five fractions over 7 days. Twenty-four patients received a total dose of 70 Gy (five fractions of 14 Gy), 158 a total dose of 60 Gy (five fractions of 12 Gy) and 30 patients a total dose of 50 Gy (five fractions of 10 Gy) applied on the 80% isodose. Ophthalmologic examinations were performed at baseline and every 3 months in the first 2 years, every 6 months until 5 years, and once a year thereafter until 10 years after radiotherapy. Assessment of visual acuity, routine ophthalmologic examinations, and measurement of tumor base dimension and height using standardized A-scan and B-scan echography were done at each visit. Funduscopy and fluorescein angiography were done when necessary to document tumor response. Results: Median tumor height and volume decreased from 4.8 mm and 270.7 mm{sup 3} at baseline to 2.6 mm and 86.6 mm{sup 3} at the last individual follow-up, respectively (p < 0.001, p < 0.001). Median visual acuity decreased from 0.55 at baseline to hand motion at the last individual follow-up (p < 0.001). Local tumor control was 95.9% after 5 years and 92.6% after 10 years. Thirty-two patients developed metastatic disease, and 22 of these patients died during the follow-up period. Conclusion: Hypofractionated stereotactic photon radiotherapy with 70 to 50 Gy delivered in five fractions in 7 days is sufficient to achieve excellent local tumor control in patients with malignant melanoma of the choroid. Disease outcome and vision are comparable to those achieved with proton beam radiotherapy. Decreasing the

  11. Effects of computational phantoms on the effective dose and two-dosimeter algorithm for external photon beams.

    PubMed

    Karimi-Shahri, K; Rafat-Motavalli, L; Miri-Hakimabad, H; Liu, L; Li, J

    2016-09-01

    In this study, the effect of computational phantoms on the effective dose (E), dosimeter responses positioned on the front (chest) and back of phantom, and two-dosimeter algorithm was investigated for external photon beams. This study was performed using Korean Typical MAN-2 (KTMAN-2), Chinese Reference Adult Male (CRAM), ICRP male reference, and Male Adult meSH (MASH) reference phantoms. Calculations were performed for beam directions in different polar and azimuthal angles using the Monte Carlo code of MCNP at energies of 0.08, 0.3, and 1MeV. Results show that the body shape significantly affects E and two-dosimeter responses when the dosimeters are indirectly irradiated. The acquired two-dosimeter algorithms are almost the same for all the mentioned phantoms except for KTMAN-2. Comparisons between the obtained E and estimated E (Eest), acquired from two-dosimeter algorithm, illustrate that the Eest is overestimated in overhead (OH) and underfoot (UF) directions. The effect of using one algorithm for all phantoms was also investigated. Results show that application of one algorithm to all reference phantoms is possible. PMID:27389880

  12. Organ dose conversion coefficients on an ICRP-based Chinese adult male voxel model from idealized external photons exposures

    NASA Astrophysics Data System (ADS)

    Liu, Liye; Zeng, Zhi; Li, Junli; Qiu, Rui; Zhang, Binquan; Ma, Jizeng; Li, Ren; Li, Wenqian; Bi, Lei

    2009-11-01

    A high-resolution whole-body voxel model called CAM representing the Chinese adult male was constructed in this paper based on a previous individual voxel model. There are more than 80 tissues and organs in CAM, including almost all organs required in the ICRP new recommendation. The mass of individual organs has been adjusted to the Chinese reference data. Special considerations were given to representing the gross spatial distribution of various bone constituents as realistically as possible during the construction of the site-specific skeleton. Organ dose conversion coefficients were calculated for six idealized external photon exposures from 10 keV to 10 MeV by using Monte Carlo simulation. The resulting dose coefficients were then compared with those from other models, e.g. CMP, ICRP 74, Rex, HDRK-man and VIP-man. Old and new effective male doses of CAM were calculated by using the tissue weighting factors from ICRP 60 and 103 Publications, respectively. Dosimetric differences between mathematical and voxel models, and the differences between Asian and Caucasian models are also discussed in this paper.

  13. Organ dose conversion coefficients on an ICRP-based Chinese adult male voxel model from idealized external photons exposures.

    PubMed

    Liu, Liye; Zeng, Zhi; Li, Junli; Qiu, Rui; Zhang, Binquan; Ma, Jizeng; Li, Ren; Li, Wenqian; Bi, Lei

    2009-11-01

    A high-resolution whole-body voxel model called CAM representing the Chinese adult male was constructed in this paper based on a previous individual voxel model. There are more than 80 tissues and organs in CAM, including almost all organs required in the ICRP new recommendation. The mass of individual organs has been adjusted to the Chinese reference data. Special considerations were given to representing the gross spatial distribution of various bone constituents as realistically as possible during the construction of the site-specific skeleton. Organ dose conversion coefficients were calculated for six idealized external photon exposures from 10 keV to 10 MeV by using Monte Carlo simulation. The resulting dose coefficients were then compared with those from other models, e.g. CMP, ICRP 74, Rex, HDRK-man and VIP-man. Old and new effective male doses of CAM were calculated by using the tissue weighting factors from ICRP 60 and 103 Publications, respectively. Dosimetric differences between mathematical and voxel models, and the differences between Asian and Caucasian models are also discussed in this paper. PMID:19841518

  14. Radiation-induced second primary cancer risks from modern external beam radiotherapy for early prostate cancer: impact of stereotactic ablative radiotherapy (SABR), volumetric modulated arc therapy (VMAT) and flattening filter free (FFF) radiotherapy

    NASA Astrophysics Data System (ADS)

    Murray, Louise J.; Thompson, Christopher M.; Lilley, John; Cosgrove, Vivian; Franks, Kevin; Sebag-Montefiore, David; Henry, Ann M.

    2015-02-01

    Risks of radiation-induced second primary cancer following prostate radiotherapy using 3D-conformal radiotherapy (3D-CRT), intensity-modulated radiotherapy (IMRT), volumetric modulated arc therapy (VMAT), flattening filter free (FFF) and stereotactic ablative radiotherapy (SABR) were evaluated. Prostate plans were created using 10 MV 3D-CRT (78 Gy in 39 fractions) and 6 MV 5-field IMRT (78 Gy in 39 fractions), VMAT (78 Gy in 39 fractions, with standard flattened and energy-matched FFF beams) and SABR (42.7 Gy in 7 fractions with standard flattened and energy-matched FFF beams). Dose-volume histograms from pelvic planning CT scans of three prostate patients, each planned using all 6 techniques, were used to calculate organ equivalent doses (OED) and excess absolute risks (EAR) of second rectal and bladder cancers, and pelvic bone and soft tissue sarcomas, using mechanistic, bell-shaped and plateau models. For organs distant to the treatment field, chamber measurements recorded in an anthropomorphic phantom were used to calculate OEDs and EARs using a linear model. Ratios of OED give relative radiation-induced second cancer risks. SABR resulted in lower second cancer risks at all sites relative to 3D-CRT. FFF resulted in lower second cancer risks in out-of-field tissues relative to equivalent flattened techniques, with increasing impact in organs at greater distances from the field. For example, FFF reduced second cancer risk by up to 20% in the stomach and up to 56% in the brain, relative to the equivalent flattened technique. Relative to 10 MV 3D-CRT, 6 MV IMRT or VMAT with flattening filter increased second cancer risks in several out-of-field organs, by up to 26% and 55%, respectively. For all techniques, EARs were consistently low. The observed large relative differences between techniques, in absolute terms, were very low, highlighting the importance of considering absolute risks alongside the corresponding relative risks, since when absolute

  15. Ultrasound-Guided Transrectal Implantation of Gold Markers for Prostate Localization During External Beam Radiotherapy: Complication Rate and Risk Factors

    SciTech Connect

    Langenhuijsen, Johan F.; Lin, Emile N.J.T. van Kiemeney, Lambertus A.; Vight, Lisette P. van der; McColl, Gill; Visser, Andries G.; Witjes, J. Alfred

    2007-11-01

    Purpose: To report the complication rate and risk factors of transrectally implanted gold markers, used for prostate position verification and correction procedures. Methods and Materials: In 209 consecutive men with localized prostate cancer, four gold markers (1 x 7 mm) were inserted under ultrasound guidance in an outpatient setting, and the toxicity was analyzed. All patients received a questionnaire regarding complications after marker implantation. The complications and risk factors were further evaluated by reviewing the medical charts. Results: Of the 209 men, 13 (6.2%) had a moderate complication, consisting of pain and fever that resolved after treatment with oral medication. In 1.9% of the men, minor voiding complaints were observed. Other minor transient complications, defined as hematuria lasting >3 days, hematospermia, and rectal bleeding, occurred in 3.8%, 18.5%, and 9.1% of the patients, respectively. These complications were seen more often in patients with advanced tumor stage, younger age, and shorter duration of hormonal therapy. Conclusion: Transrectal gold marker implantation for high-precision prostate radiotherapy is a safe and well-tolerated procedure.

  16. Development of a Synthetic Adaptive Neuro-Fuzzy Prediction Model for Tumor Motion Tracking in External Radiotherapy by Evaluating Various Data Clustering Algorithms.

    PubMed

    Ghorbanzadeh, Leila; Torshabi, Ahmad Esmaili; Nabipour, Jamshid Soltani; Arbatan, Moslem Ahmadi

    2016-04-01

    In image guided radiotherapy, in order to reach a prescribed uniform dose in dynamic tumors at thorax region while minimizing the amount of additional dose received by the surrounding healthy tissues, tumor motion must be tracked in real-time. Several correlation models have been proposed in recent years to provide tumor position information as a function of time in radiotherapy with external surrogates. However, developing an accurate correlation model is still a challenge. In this study, we proposed an adaptive neuro-fuzzy based correlation model that employs several data clustering algorithms for antecedent parameters construction to avoid over-fitting and to achieve an appropriate performance in tumor motion tracking compared with the conventional models. To begin, a comparative assessment is done between seven nuero-fuzzy correlation models each constructed using a unique data clustering algorithm. Then, each of the constructed models are combined within an adaptive sevenfold synthetic model since our tumor motion database has high degrees of variability and that each model has its intrinsic properties at motion tracking. In the proposed sevenfold synthetic model, best model is selected adaptively at pre-treatment. The model also updates the steps for each patient using an automatic model selectivity subroutine. We tested the efficacy of the proposed synthetic model on twenty patients (divided equally into two control and worst groups) treated with CyberKnife synchrony system. Compared to Cyberknife model, the proposed synthetic model resulted in 61.2% and 49.3% reduction in tumor tracking error in worst and control group, respectively. These results suggest that the proposed model selection program in our synthetic neuro-fuzzy model can significantly reduce tumor tracking errors. Numerical assessments confirmed that the proposed synthetic model is able to track tumor motion in real time with high accuracy during treatment. PMID:25765021

  17. Radical Prostatectomy versus External Beam Radiotherapy for cT1-4N0M0 Prostate Cancer: Comparison of Patient Outcomes Including Mortality

    PubMed Central

    Taguchi, Satoru; Fukuhara, Hiroshi; Shiraishi, Kenshiro; Nakagawa, Keiichi; Morikawa, Teppei; Kakutani, Shigenori; Takeshima, Yuta; Miyazaki, Hideyo; Fujimura, Tetsuya; Nakagawa, Tohru; Kume, Haruki; Homma, Yukio

    2015-01-01

    Background Although radical prostatectomy (RP) and external beam radiotherapy (EBRT) have been considered as comparable treatments for localized prostate cancer (PC), it is controversial which treatment is better. The present study aimed to compare outcomes, including mortality, of RP and EBRT for localized PC. Methods We retrospectively analyzed 891 patients with cT1-4N0M0 PC who underwent either RP (n = 569) or EBRT (n = 322) with curative intent at our single institution between 2005 and 2012. Of the EBRT patients, 302 (93.8%) underwent intensity-modulated radiotherapy. Primary endpoints were overall survival (OS) and cancer-specific survival (CSS). Related to these, other-cause mortality (OCM) was also calculated. Biochemical recurrence-free survival was assessed as a secondary endpoint. Cox proportional hazards model was used for multivariate analysis. Results Median follow-up durations were 53 and 45 months, and median ages were 66 and 70 years (P <0.0001), in the RP and EBRT groups, respectively. As a whole, significantly better prognoses of the RP group than the EBRT group were observed for both OS and CSS, although OCM was significantly higher in the EBRT group. There was no death from PC in men with low and intermediate D’Amico risks, except one with intermediate-risk in the EBRT group. In high-risk patients, significantly more patients died from PC in the EBRT group than the RP group. Multivariate analysis demonstrated the RP group to be an independent prognostic factor for better CSS. On the other hand, the EBRT group had a significantly longer biochemical recurrence-free survival than the RP group. Conclusions Mortality outcomes of both RP and EBRT were generally favorable in low and intermediate risk patients. Improvement of CSS in high risk patients was seen in patients receiving RP over those receiving EBRT. PMID:26506569

  18. Poster — Thur Eve — 48: Dosimetric dependence on bone backscatter in orthovoltage radiotherapy: A Monte Carlo photon fluence spectral study

    SciTech Connect

    Chow, J; Grigor, G

    2014-08-15

    This study investigated dosimetric impact due to the bone backscatter in orthovoltage radiotherapy. Monte Carlo simulations were used to calculate depth doses and photon fluence spectra using the EGSnrc-based code. Inhomogeneous bone phantom containing a thin water layer (1–3 mm) on top of a bone (1 cm) to mimic the treatment sites of forehead, chest wall and kneecap was irradiated by the 220 kVp photon beam produced by the Gulmay D3225 x-ray machine. Percentage depth doses and photon energy spectra were determined using Monte Carlo simulations. Results of percentage depth doses showed that the maximum bone dose was about 210–230% larger than the surface dose in the phantoms with different water thicknesses. Surface dose was found to be increased from 2.3 to 3.5%, when the distance between the phantom surface and bone was increased from 1 to 3 mm. This increase of surface dose on top of a bone was due to the increase of photon fluence intensity, resulting from the bone backscatter in the energy range of 30 – 120 keV, when the water thickness was increased. This was also supported by the increase of the intensity of the photon energy spectral curves at the phantom and bone surface as the water thickness was increased. It is concluded that if the bone inhomogeneity during the dose prescription in the sites of forehead, chest wall and kneecap with soft tissue thickness = 1–3 mm is not considered, there would be an uncertainty in the dose delivery.

  19. A comparative dosimetric study on tangential photon beams, intensity-modulated radiation therapy (IMRT) and modulated electron radiotherapy (MERT) for breast cancer treatment

    NASA Astrophysics Data System (ADS)

    Ma, C.-M.; Ding, M.; Li, J. S.; Lee, M. C.; Pawlicki, T.; Deng, J.

    2003-04-01

    Recently, energy- and intensity-modulated electron radiotherapy (MERT) has garnered a growing interest for the treatment of superficial targets. In this work, we carried out a comparative dosimetry study to evaluate MERT, photon beam intensity-modulated radiation therapy (IMRT) and conventional tangential photon beams for the treatment of breast cancer. A Monte Carlo based treatment planning system has been investigated, which consists of a set of software tools to perform accurate dose calculation, treatment optimization, leaf sequencing and plan analysis. We have compared breast treatment plans generated using this home-grown treatment optimization and dose calculation software for these treatment techniques. The MERT plans were planned with up to two gantry angles and four nominal energies (6, 9, 12 and 16 MeV). The tangential photon treatment plans were planned with 6 MV wedged photon beams. The IMRT plans were planned using both multiple-gantry 6 MV photon beams or two 6 MV tangential beams. Our results show that tangential IMRT can reduce the dose to the lung, heart and contralateral breast compared to conventional tangential wedged beams (up to 50% reduction in high dose volume or 5 Gy in the maximum dose). MERT can reduce the maximum dose to the lung by up to 20 Gy and to the heart by up to 35 Gy compared to conventional tangential wedged beams. Multiple beam angle IMRT can significantly reduce the maximum dose to the lung and heart (up to 20 Gy) but it induces low and medium doses to a large volume of normal tissues including lung, heart and contralateral breast. It is concluded that MERT has superior capabilities to achieve dose conformity both laterally and in the depth direction, which will be well suited for treating superficial targets such as breast cancer.

  20. Evaluation of the use of surrogate tissues for calculating radiation dose to lymphatic nodes from external photon beams

    PubMed Central

    Lamart, Stephanie; Moroz, Brian E.; Lee, Choonsik

    2013-01-01

    Lymphatic node chains of the human body are particularly difficult to realistically model in computational human phantoms. In the absence of a lymphatic node model, researchers have used the following surrogate tissues to calculate the radiation dose to the lymphatic nodes: blood vessels, muscle and the combination of the muscle and adipose tissues. In the present work, the authors investigated whether and in which extent the use of different surrogate tissues is appropriate to assess the lymph node dose, using a realistic model of lymphatic nodes that the authors recently reported. Using a Monte Carlo radiation transport method coupled with the adult male hybrid phantom that included the lymph node model, the air kerma-to-absorbed dose conversion coefficients (Gy Gy−1) to the lymph nodes and other tissues used as surrogates for external photon beams of 15 discrete energies (0.015–10 MeV) were computed using the following six idealised geometries: anterior–posterior (AP), posterior–anterior (PA), right lateral, left lateral, rotational and isotropic. To validate the results of this study, the lymph node dose calculated here was compared with the dose published by the International Commission on Radiological Protection for the adult male reference phantom. The lymph node dose conversion coefficients with the values calculated for the blood vessels, muscle, adipose tissue and the combination of muscle and adipose tissues were then compared. It was found that muscle was the best estimator for the lymph nodes, with a dose difference averaged across energies >0.08 MeV of <8 % in all irradiation geometries excluding the AP and PA geometries for which the blood vessels were found to be the best estimator. In conclusion, muscle and blood vessels may preferably be used as surrogate tissues in the absence of lymphatic nodes in a given voxel phantom. For energies <0.08 MeV, for which the authors observed a difference of up to 30-fold, an explicit lymph node model may

  1. External beam radiotherapy and abiraterone in men with localized prostate cancer: safety and effect on tissue androgens

    PubMed Central

    Cho, Eunpi; Mostaghel, Elahe A.; Russell, Kenneth J.; Liao, Jay J.; Konodi, Mark A.; Kurland, Brenda F.; Marck, Brett T.; Matsumoto, Alvin M.; Dalkin, Bruce L.; Montgomery, R. Bruce

    2015-01-01

    Purpose/Objectives Optimizing androgen suppression may provide better control of localized prostate cancer (PCa). Numerous trials have supported the benefit of combining androgen deprivation with definitive radiotherapy in men with locally advanced or high-grade disease. Addition of abiraterone to LHRH agonist (LHRHa) with radiation has not been reported. We examined the safety of this combination as well as its impact on androgen suppression. Materials/Methods A prospective, phase II study was conducted in men with localized PCa treated with 6 months of neoadjuvant and concurrent abiraterone with LHRHa and radiation. Duration of adjuvant LHRHa was at discretion of treating clinician. Prostate biopsies were obtained prior to start of therapy and prior to radiation. Serum and tissue androgen levels were measured by liquid chromatography-tandem mass spectrometry. Results 22 men with intermediate (3) and high-risk PCa (19) received study therapy. 16 men completed the intended course of abiraterone, and 19 men completed planned radiation to 77.4–81 Gy. Radiation to pelvic nodes was administered in 20 men. The following grade 3 toxicities were reported: lymphopenia (14),, fatigue (1), transaminitis (2), hypertension (2), and hypokalemia (1). There were no grade 4 toxicities. All 21 men who complied with at least 3 months of abiraterone had pre-radiation PSA nadir of <0.3. Median levels of tissue androgens downstream of CYP17A were significantly suppressed after treatment with abiraterone, and upstream steroids were increased. At median follow-up of 21 months (range 3–37), only one patient (who had discontinued abiraterone at 3 months) had biochemical relapse. Conclusions Addition of abiraterone to LHRHa with radiation is safe and achieves effective prostatic androgen suppression. Preliminary analysis of the clinical data is also promising with excellent PSA nadir and no relapse to date in this high-risk population. PMID:25772183

  2. Comparison of Three-Dimensional (3D) Conformal Proton Radiotherapy (RT), 3D Conformal Photon RT, and Intensity-Modulated RT for Retroperitoneal and Intra-Abdominal Sarcomas

    SciTech Connect

    Swanson, Erika L.; Indelicato, Daniel J.; Louis, Debbie; Flampouri, Stella; Li, Zuofeng; Morris, Christopher G.; Paryani, Nitesh; Slopsema, Roelf

    2012-08-01

    Purpose: To compare three-dimensional conformal proton radiotherapy (3DCPT), intensity-modulated photon radiotherapy (IMRT), and 3D conformal photon radiotherapy (3DCRT) to predict the optimal RT technique for retroperitoneal sarcomas. Methods and Materials: 3DCRT, IMRT, and 3DCPT plans were created for treating eight patients with retroperitoneal or intra-abdominal sarcomas. The clinical target volume (CTV) included the gross tumor plus a 2-cm margin, limited by bone and intact fascial planes. For photon plans, the planning target volume (PTV) included a uniform expansion of 5 mm. For the proton plans, the PTV was nonuniform and beam-specific. The prescription dose was 50.4 Gy/Cobalt gray equivalent CGE. Plans were normalized so that >95% of the CTV received 100% of the dose. Results: The CTV was covered adequately by all techniques. The median conformity index was 0.69 for 3DCPT, 0.75 for IMRT, and 0.51 for 3DCRT. The median inhomogeneity coefficient was 0.062 for 3DCPT, 0.066 for IMRT, and 0.073 for 3DCRT. The bowel median volume receiving 15 Gy (V15) was 16.4% for 3DCPT, 52.2% for IMRT, and 66.1% for 3DCRT. The bowel median V45 was 6.3% for 3DCPT, 4.7% for IMRT, and 15.6% for 3DCRT. The median ipsilateral mean kidney dose was 22.5 CGE for 3DCPT, 34.1 Gy for IMRT, and 37.8 Gy for 3DCRT. The median contralateral mean kidney dose was 0 CGE for 3DCPT, 6.4 Gy for IMRT, and 11 Gy for 3DCRT. The median contralateral kidney V5 was 0% for 3DCPT, 49.9% for IMRT, and 99.7% for 3DCRT. Regardless of technique, the median mean liver dose was <30 Gy, and the median cord V50 was 0%. The median integral dose was 126 J for 3DCPT, 400 J for IMRT, and 432 J for 3DCRT. Conclusions: IMRT and 3DCPT result in plans that are more conformal and homogenous than 3DCRT. Based on Quantitative Analysis of Normal Tissue Effects in Clinic benchmarks, the dosimetric advantage of proton therapy may be less gastrointestinal and genitourinary toxicity.

  3. Health-Related Quality of Life After Single-Fraction High-Dose-Rate Brachytherapy and Hypofractionated External Beam Radiotherapy for Prostate Cancer

    SciTech Connect

    Morton, Gerard C.; Loblaw, D. Andrew; Chung, Hans; Tsang, Gail; Sankreacha, Raxa; Deabreu, Andrea; Zhang Liying; Mamedov, Alexandre; Cheung, Patrick; Batchelar, Deidre; Danjoux, Cyril; Szumacher, Ewa

    2011-08-01

    Purpose: To investigate the change in health-related quality of life for men after high-dose-rate brachytherapy and external beam radiotherapy for prostate cancer and the factors associated with this change. Methods and Materials: Eligible patients had clinically localized intermediate-risk prostate cancer. The patients received high-dose-rate brachytherapy as a single 15-Gy implant, followed by external beam radiotherapy to 37.5 Gy in 15 fractions. The patients were monitored prospectively for toxicity (Common Terminology Criteria for Adverse Events, version 3.0) and health-related quality of life (Expanded Prostate Cancer Index Composite [EPIC]). The proportion of patients developing a clinically significant difference in the EPIC domain score (minimally important difference of >0.5 standard deviation) was determined and correlated with the baseline clinical and dosimetric factors. The study accrued 125 patients, with a median follow-up of 24 months. Results: By 24 months, 23% had Grade 2 urinary toxicity and only 5% had Grade 2 bowel toxicity, with no Grade 3 toxicity. The proportion of patients reporting a significant decrease in EPIC urinary, bowel, sexual, and hormonal domain scores was 53%, 51%, 45%, and 40% at 12 months and 57%, 65%, 51%, and 30% at 24 months, respectively. The proportion with a >1 standard deviation decrease in the EPIC urinary, bowel, sexual, and hormonal domain scores was 38%, 36%, 24%, and 20% at 12 months and 46%, 48%, 19%, and 8% at 24 months, respectively. On multivariate analysis, the dose to 10% of the urethra was associated with a decreasing EPIC urinary domain score (p = .0089) and, less strongly (p = .0312) with a decreasing hormonal domain score. No association was found between the prostate volume, bladder dose, or high-dose volume and urinary health-related quality of life. A high baseline International Index of Erectile Function score was associated (p = .0019) with a decreasing sexual domain score. The optimal maximal dose

  4. SU-E-T-283: Research of the Irradiation Damage to the Skin Cell by the Contaminative Electron in External Radiotherapy

    SciTech Connect

    Xiong, Z; Lin, H; Jing, J; Dai, Y; Cai, J

    2014-06-01

    Purpose: To investigate the micro-damage mechanism of the contaminative electron to the skin cell in external radiotherapy, the cell damage yield was simulated. Methods: The physical interaction and the energy deposited events of contaminative electrons in the cell DNA were modeled based on Geant4-DNA low energy physical model. The densitybased cluster mining algorithm was used to analyze the micro-damage yield and obtain its detailed compositive information. By taking the irradiation sensitive parameter and the clinical feature dose threshold of the skin cell into consideration, the damage features of the low energy contaminative electron to the skin cell were studied. The DSB and SSB yield and ratio, the cluster size and the root mean square radius, the cell SF and the lethal coefficient ε of the complex cDSB were researched. Results: For some very low energy electrons such as 20keV and 100keV, the cluster size can be more than 5 SSBs. The irradiation protection will be more crucial for the later response and the high α tissue. The lethal coefficient ε of the complex cDSB will increase with the incident electron number and the accumulative dose increasing for the dose square term in LQ model. However, the ε increment will increase 3%∼15% when the incident electron increases up to 100000. Conclusion: The simulation of the direct physical damage of the cell can be adjusted by a probability parameter to offset the simulation of the indirect biochemical damage. Thus the micro-damage mechanism of the contaminative electron to the skin cell can be detected at a certain extent by Monte Carlo physical simulation. This damage model of the low energy electron to DNA and these simulated results could be used to evaluate the damage effect of the low energy contaminative electron to the skin cells in the external radiotherapy. Strategic Priority Research Program of the Chinese Academy of Sciences (XDA03040000), Fundamental Research Funds for the Central Universities

  5. WE-G-BRE-06: New Potential for Enhancing External Beam Radiotherapy for Lung Cancer Using FDA-Approved Concentrations of Cisplatin Or Carboplatin Nanoparticles Administered Via Inhalation

    SciTech Connect

    Hao, Y; Altundal, Y; Sajo, E; Detappe, A; Makrigiorgos, G; Berbeco, R; Ngwa, W

    2014-06-15

    Purpose: This study investigates, for the first time, the dose enhancement to lung tumors due to cisplatin nanoparticles (CNPs) and carboplatin nanoparticles (CBNPs) administered via inhalation route (IR) during external beam radiotherapy. Methods: Using Monte Carlo generated 6 MV energy fluence spectra, a previously employed analytic method was used to estimate dose enhancement to lung tumor due to radiation-induced photoelectrons from CNPs administered via IR in comparison to intravenous (IV) administration. Previous studies have indicated about 5% of FDA-approved cisplatin concentrations reach the lung tumor via IV. Meanwhile recent experimental studies indicate that 3.5–14.6 times higher concentrations of CNPs can reach the lung tumors by IR compared to IV. Taking these into account, the dose enhancement factor (DEF) defined as the ratio of the dose with and without CNPs was calculated for field size of 10 cm × 10 cm (sweeping gap), for a range of tumor depths and tumor sizes. Similar calculations were done for CBNPs. Results: For IR with 3.5 times higher concentrations than IV, and 2 cm diameter tumor, clinically significant DEF values of 1.19–1.30 were obtained for CNPs at 3–10 cm depth, respectively, in comparison to 1.06–1.09 for IV. For CBNPs, DEF values of 1.26–1.41 were obtained in comparison to 1.07–1.12 for IV. For IR with 14.6 times higher concentrations, higher DEF values were obtained e.g. 1.81–2.27 for CNPs. DEF increased with increasing field size or decreasing tumor size. Conclusions: Our preliminary results indicate that major dose enhancement to lung tumors can be achieved using CNPs/CBNPs administered via IR, in contrast to IV administration during external beam radiotherapy. These findings highlight a potential new approach for radiation boosting to lung tumors using CNPs/CBNPs administered via IR. This would, especially, be applicable during concomitant chemoradiotherapy, potentially allowing for dose enhancement while

  6. Localized Dose Enhancement to Tumor Blood Vessel Endothelial Cells via Megavoltage X-rays and Targeted Gold Nanoparticles: New Potential for External Beam Radiotherapy

    SciTech Connect

    Berbeco, Ross I.; Ngwa, Wilfred; Makrigiorgos, G. Mike

    2011-09-01

    Purpose: Tumor endothelial cell damage during radiation therapy may contribute significantly to tumor eradication and treatment efficacy. Gold nanoparticles (AuNPs) delivered preferentially to the walls of tumor blood vessels produce low-energy, short-range photoelectrons during external beam radiotherapy, boosting dose to the tumor microvasculature. In this study dosimetry at the single-cell level is used to estimate the anticipated AuNP-mediated dose enhancement to tumor endothelial cells during 6-MV X-ray irradiation. Methods and Materials: Endothelial cells are modeled as thin slabs with 100-nm-diameter AuNPs attached within the blood vessel. The number of photoelectrons emitted per AuNP per gray of X-rays is computed at multiple points along the external beam central axis by use of a Monte Carlo-generated energy fluence spectrum. The energy deposited from AuNP emissions to the endothelium is calculated based on an analytic method incorporating the energy-loss formula of Cole. The endothelial dose enhancement factor (EDEF) is the ratio of the overall (externally plus internally generated) dose to endothelial cells in the presence of AuNPs to the dose without AuNPs (from the external beam only). Results: At 20-cm depth, the EDEF is 1.7 (70% dose increase) for an intravascular AuNP concentration of 30 mg/g. Most of this dose enhancement arises from the low-energy (approximately 100 keV) portion of the linear accelerator X-ray spectrum. Furthermore, for AuNP concentrations ranging from 7 to 140 mg/g, EDEF values of 1.2 to 4.4 (20-340% dose increase) are calculated. Conclusions: In contrast to calculations assuming that AuNPs distributed homogeneously throughout the target volume (macrodosimetry), our cellular microdosimetry calculations predict a major dose enhancement to tumor microvasculature from conventional linear accelerator X-rays. This effect may enable the delivery of ablative therapeutic doses to these sensitive microstructures while maintaining

  7. Review of ultrasound image guidance in external beam radiotherapy part II: intra-fraction motion management and novel applications.

    PubMed

    O'Shea, Tuathan; Bamber, Jeffrey; Fontanarosa, Davide; van der Meer, Skadi; Verhaegen, Frank; Harris, Emma

    2016-04-21

    Imaging has become an essential tool in modern radiotherapy (RT), being used to plan dose delivery prior to treatment and verify target position before and during treatment. Ultrasound (US) imaging is cost-effective in providing excellent contrast at high resolution for depicting soft tissue targets apart from those shielded by the lungs or cranium. As a result, it is increasingly used in RT setup verification for the measurement of inter-fraction motion, the subject of Part I of this review (Fontanarosa et al 2015 Phys. Med. Biol. 60 R77-114). The combination of rapid imaging and zero ionising radiation dose makes US highly suitable for estimating intra-fraction motion. The current paper (Part II of the review) covers this topic. The basic technology for US motion estimation, and its current clinical application to the prostate, is described here, along with recent developments in robust motion-estimation algorithms, and three dimensional (3D) imaging. Together, these are likely to drive an increase in the number of future clinical studies and the range of cancer sites in which US motion management is applied. Also reviewed are selections of existing and proposed novel applications of US imaging to RT. These are driven by exciting developments in structural, functional and molecular US imaging and analytical techniques such as backscatter tissue analysis, elastography, photoacoustography, contrast-specific imaging, dynamic contrast analysis, microvascular and super-resolution imaging, and targeted microbubbles. Such techniques show promise for predicting and measuring the outcome of RT, quantifying normal tissue toxicity, improving tumour definition and defining a biological target volume that describes radiation sensitive regions of the tumour. US offers easy, low cost and efficient integration of these techniques into the RT workflow. US contrast technology also has potential to be used actively to assist RT by manipulating the tumour cell environment and by

  8. Review of ultrasound image guidance in external beam radiotherapy part II: intra-fraction motion management and novel applications

    NASA Astrophysics Data System (ADS)

    O'Shea, Tuathan; Bamber, Jeffrey; Fontanarosa, Davide; van der Meer, Skadi; Verhaegen, Frank; Harris, Emma

    2016-04-01

    Imaging has become an essential tool in modern radiotherapy (RT), being used to plan dose delivery prior to treatment and verify target position before and during treatment. Ultrasound (US) imaging is cost-effective in providing excellent contrast at high resolution for depicting soft tissue targets apart from those shielded by the lungs or cranium. As a result, it is increasingly used in RT setup verification for the measurement of inter-fraction motion, the subject of Part I of this review (Fontanarosa et al 2015 Phys. Med. Biol. 60 R77-114). The combination of rapid imaging and zero ionising radiation dose makes US highly suitable for estimating intra-fraction motion. The current paper (Part II of the review) covers this topic. The basic technology for US motion estimation, and its current clinical application to the prostate, is described here, along with recent developments in robust motion-estimation algorithms, and three dimensional (3D) imaging. Together, these are likely to drive an increase in the number of future clinical studies and the range of cancer sites in which US motion management is applied. Also reviewed are selections of existing and proposed novel applications of US imaging to RT. These are driven by exciting developments in structural, functional and molecular US imaging and analytical techniques such as backscatter tissue analysis, elastography, photoacoustography, contrast-specific imaging, dynamic contrast analysis, microvascular and super-resolution imaging, and targeted microbubbles. Such techniques show promise for predicting and measuring the outcome of RT, quantifying normal tissue toxicity, improving tumour definition and defining a biological target volume that describes radiation sensitive regions of the tumour. US offers easy, low cost and efficient integration of these techniques into the RT workflow. US contrast technology also has potential to be used actively to assist RT by manipulating the tumour cell environment and by

  9. /sup 125/Iodine implants as an adjuvant to surgery and external beam radiotherapy in the management of locally advanced head and neck cancer

    SciTech Connect

    Martinez, A.; Goffinet, D.R.; Fee, W.; Goode, R.; Cox, R.S.

    1983-03-15

    /sup 125/Iodine seeds either individually placed or inserted into absorbable Vicryl suture carriers were utilized in conjunction with surgery and external beam radiotherapy in an attempt to increase local control rates in patients with (1) advanced oropharyngeal and laryngopharyngeal cancers (T3-T4, N2-N3), (2) massive cervical lymphadenopathy (N3) and an unknown primary site and (3) locally recurrent head and neck cancers. Forty-eight patients were treated with 55 implants. The carotid artery was implanted in 15 patients, while seven patients had seeds inserted into the base of the skull region, and another three patients had implants near cranial nerves. Eighteen of the 48 patients were treated for cure. The actuarial survival at five years in this subgroup was 50%. The overall local control in the head and neck area was 58%. In this group no patients to date have had a local failure in the implanted volume. Seventeen patients with comparable stage of disease treated prior to 1974 with curative intent without /sup 125/I implants were analyzed retrospectively for comparison with the implanted patients. The actuarial survival of these patients was 18% and the overall head and neck control was 21%. These differences are statistically significant at a P value of 0.01 and 0.007, respectively. Seventeen patients received implants for local recurrence. The local control in the head and neck area was 50%; however, the 2.5 year actuarial survival was only 17%. The complication rate was 11% (six of 55 implants). The improved survival, the high local control, and the minimal complication rates in this series makes the intraoperative implantation of /sup 125/I seeds and effective adjunctive treatment to surgery and external beam irradiation.

  10. /sup 125/I implants as an adjuvant to surgery and external beam radiotherapy in the management of locally advanced head and neck cancer

    SciTech Connect

    Martinez, A.; Goffinet, D.R.; Fee, W.; Goode, R.; Cox, R.S.

    1983-03-15

    /sup 125/I seeds either individually placed or inserted into absorbable Vicryl suture carriers were utilized in conjunction with surgery and external beam radiotherapy in an attempt to increase local control rates in patients with advanced oropharyngeal and laryngopharyngeal cancers (T3-T4, N2-N3), massive cervical lymphadenopathy (N3) and an unknown primary site and locally recurrent head and neck cancers. Forty-eight patients were treated with 55 implants. The carotid artery was implanted in 15 patients, while seven patients had seeds inserted into the base of the skull region, and another three patients had implants near cranial nerves. Eighteen of the 48 patients were treated for cure. The actuarial survival at five years in this subgroup was 50%. The overall local control in the head and neck area was 58%. In this group no patients to date have had a local failure in the implanted volume. Seventeen patients with comparable stage of disease treated prior to 1974 with curative intent without /sup 125/I implants were analyzed retrospectively for comparison with the implanted patients. The actuarial survival of these patients was 18% and the overall head and neck control was 21%. These differences are statistically significant at a P value of 0.01 and 0.007, respectively. Seventeen patients received implants for local recurrence. The local control in the head and neck area was 50%; however, the 2.5 year actuarial survival was only 17%. The complication rate was 11% (six of 55 implants). The improved survival, the high local control, and the minimal complication rates in this series makes the intraoperative implantation of /sup 125/I seeds and effective adjunctive treatment to surgery and external beam irradiation.

  11. Use of External Beam Radiotherapy Is Associated With Reduced Incidence of Second Primary Head and Neck Cancer: A SEER Database Analysis

    SciTech Connect

    Rusthoven, Kyle; Chen Changhu Raben, David; Kavanagh, Brian

    2008-05-01

    Purpose: Patients with head and neck cancer have a significant risk of developing a second primary cancer of the head and neck. We hypothesized that treatment with external beam radiotherapy (RT) might reduce this risk, because RT can eradicate occult foci of second head and neck cancer (HNCA). Methods and Materials: The data of patients with Surveillance, Epidemiology, and End Results Historic Stage A localized squamous cell carcinoma of the oral cavity, larynx, and pharynx were queried using the Surveillance, Epidemiology, and End Results database. For patients treated with or without RT, the incidence of second HNCA was determined and compared using the log-rank method. Cox proportional hazards analysis was performed for each site, evaluating the influence of covariates on the risk of second HNCA. Results: Between 1973 and 1997, 27,985 patients were entered with localized HNCA. Of these patients, 44% had received RT and 56% had not. The 15-year incidence of second HNCA was 7.7% with RT vs. 10.5% without RT (hazard ratio 0.71, p <0.0001). The effect of RT was more profound in patients diagnosed between 1988 and 1997 (hazard ratio 0.53, p <0.0001) and those with pharynx primaries (hazard ratio 0.47, p <0.0001). On multivariate analysis, RT was associated with a reduced risk of second HNCA for pharynx (p <0.0001) and larynx (p = 0.04) tumors. For oral cavity primaries, RT was associated with an increased risk of second HNCA in patients treated before 1988 (p <0.001), but had no influence on patients treated between 1988 and 1997 (p = 0.91). Conclusion: For localized HNCA, RT is associated with a reduced incidence of second HNCA. These observations are consistent with the eradication of microscopic foci of second HNCA with external beam RT.

  12. Chlorotoxin-Conjugated Multifunctional Dendrimers Labeled with Radionuclide 131I for Single Photon Emission Computed Tomography Imaging and Radiotherapy of Gliomas.

    PubMed

    Zhao, Lingzhou; Zhu, Jingyi; Cheng, Yongjun; Xiong, Zhijuan; Tang, Yueqin; Guo, Lilei; Shi, Xiangyang; Zhao, Jinhua

    2015-09-01

    Chlorotoxin-conjugated multifunctional dendrimers labeled with radionuclide 131I were synthesized and utilized for targeted single photon emission computed tomography (SPECT) imaging and radiotherapy of cancer. In this study, generation five amine-terminated poly(amidoamine) dendrimers were used as a platform to be sequentially conjugated with polyethylene glycol (PEG), targeting agent chlorotoxin (CTX), and 3-(4'-hydroxyphenyl)propionic acid-OSu (HPAO). This was followed by acetylation of the remaining dendrimer terminal amines and radiolabeling with 131I to form the targeted theranostic dendrimeric nanoplatform. We show that the dendrimer platform possessing approximately 7.7 CTX and 21.1 HPAO moieties on each dendrimer displays excellent cytocompatibility in a given concentration range (0-20 μM) and can specifically target cancer cells overexpressing matrix metallopeptidase 2 (MMP2) due to the attached CTX. With the attached HPAO moiety having the phenol group, the dendrimer platform can be effectively labeled with radioactive 131I with good stability and high radiochemical purity. Importantly, the 131I labeling renders the dendrimer platform with an ability to be used for targeted SPECT imaging and radiotherapy of an MMP2-overexpressing glioma model in vivo. The developed radiolabeled multifunctional dendrimeric nanoplatform may hold great promise to be used for targeted theranostics of human gliomas. PMID:26291070

  13. Histologically Proven Radiation-Induced Brainstem Glioma 93 Months After External Beam Radiotherapy for Pituitary Macroadenoma: Radiation Treatment Dose and Volume Correlation.

    PubMed

    Abboud, Salim E; Wolansky, Leo J; Manjila, Sunil V; Lo, Simon S; Arafah, Baha M; Selman, Warren R; Couce, Marta E; Rogers, Lisa R

    2015-01-01

    Patient is a 29-year-old with a history of recurrent growth hormone-secreting pituitary macroadenoma diagnosed 12 years prior to presentation. Eight years prior to current presentation, the patient underwent re-resection and received 50.4 Gy external beam radiotherapy (EBRT) in 28 fractions of 1.8 Gy each. Serial postradiation MRIs demonstrated regression in pituitary tumor size. Patient presented with new headaches 7.5 years after completing EBRT. Brain MRI demonstrated new FLAIR hyperintensity and contrast enhancement within the pons and medulla, corresponding to the 36 Gy isodose line of each radiation dose fraction. Differential diagnosis included radiation necrosis and radiation-induced glioma (RIG). The patient's neurologic exam worsened over the following 4 months. MRI showed progressive increase in mass effect, extent of FLAIR hyperintensity, and contrast enhancement in the brainstem. Stereotactic-assisted biopsy showed infiltrating astrocytoma with moderate atypia. A PubMed search showed this is the first case of histologically verified brainstem RIG correlated with 3-dimensional conformational radiation therapy dose and volume planning following EBRT for a pituitary adenoma. The rare occurrence of brainstem RIG after radiation therapy for pituitary tumor supports the need for long-term imaging monitoring of such patients. PMID:25345677

  14. Hemoglobin levels do not predict biochemical outcome for localized prostate cancer treated with neoadjuvant androgen-suppression therapy and external-beam radiotherapy

    SciTech Connect

    Pai, Howard Huaihan . E-mail: hpai@bccancer.bc.ca; Ludgate, Charles; Pickles, Tom; Paltiel, Chuck M.Sc.; Agranovich, Alex; Berthelet, Eric; Duncan, Graeme; Kim-Sing, Charmaine; Kwan, Winkle; Lim, Jan; Liu, Mitchell; Tyldesley, Scott

    2006-07-15

    Purpose: To investigate whether hemoglobin (Hb) levels affect outcome in men with localized prostate adenocarcinoma (LPA) treated with neoadjuvant androgen-suppression therapy (NAST) and external-beam radiotherapy (EBRT). Methods and Materials: A total of 563 men with LPA treated with NAST (median: 5.3 months) and EBRT who had Hb levels during treatment were retrospectively reviewed. Patient, tumor, and treatment variables, including the following Hb variables, were subjected to univariate and multivariable analyses to identify factors that predict biochemical control (bNED) and overall survival (OS): pre-EBRT Hb, Hb nadir during EBRT, and change in Hb from pre-EBRT to nadir during EBRT. Results: Median PSA follow-up was 4.25 years. Forty-nine percent of men were anemic during EBRT, with a median Hb of 13.4 g/dL, and 68% experienced a decline in Hb from pre-EBRT to during EBRT of median 0.6 g/dL. Five-year Nadir + 2 bNED and OS rates were similar for anemic and nonanemic patients during EBRT. High percent-positive biopsies, PSA and Gleason score, and use of AA monotherapy predicted worse bNED. High stage and age predicted worse OS. Hb variables were not predictive of bNED or OS. Conclusions: Anemia is a common side effect of NAST and is usually mild. Hb levels, however, do not predict biochemical control or survival.

  15. Evaluation of the effect of tooth and dental restoration material on electron dose distribution and production of photon contamination in electron beam radiotherapy.

    PubMed

    Bahreyni Toossi, Mohammad Taghi; Ghorbani, Mahdi; Akbari, Fatemeh; Mehrpouyan, Mohammad; Sobhkhiz Sabet, Leila

    2016-03-01

    The aim of this study is to evaluate the effect of tooth and dental restoration materials on electron dose distribution and photon contamination production in electron beams of a medical linac. This evaluation was performed on 8, 12 and 14 MeV electron beams of a Siemens Primus linac. MCNPX Monte Carlo code was utilized and a 10 × 10 cm(2) applicator was simulated in the cases of tooth and combinations of tooth and Ceramco C3 ceramic veneer, tooth and Eclipse alloy and tooth and amalgam restoration materials in a soft tissue phantom. The relative electron and photon contamination doses were calculated for these materials. The presence of tooth and dental restoration material changed the electron dose distribution and photon contamination in phantom, depending on the type of the restoration material and electron beam's energy. The maximum relative electron dose was 1.07 in the presence of tooth including amalgam for 14 MeV electron beam. When 100.00 cGy was prescribed for the reference point, the maximum absolute electron dose was 105.10 cGy in the presence of amalgam for 12 MeV electron beam and the maximum absolute photon contamination dose was 376.67 μGy for tooth in 14 MeV electron beam. The change in electron dose distribution should be considered in treatment planning, when teeth are irradiated in electron beam radiotherapy. If treatment planning can be performed in such a way that the teeth are excluded from primary irradiation, the potential errors in dose delivery to the tumour and normal tissues can be avoided. PMID:26581762

  16. Image-Guided Intensity-Modulated Photon Radiotherapy Using Multifractionated Regimen to Paraspinal Chordomas and Rare Sarcomas

    SciTech Connect

    Terezakis, Stephanie A. Lovelock, D. Michael; Bilsky, Mark H.; Hunt, Margaret A.; Zatcky, Joan N.P.; Yamada, Yoshiya

    2007-12-01

    Purpose: Image-guided intensity-modulated radiotherapy enables delivery of high-dose radiation to tumors close to the spinal cord. We report our experience with multifractionated regimens using image-guided intensity-modulated radiotherapy to treat gross paraspinal disease to doses beyond cord tolerance. Methods and Materials: We performed a retrospective review of 27 consecutive patients with partially resected or unresectable paraspinal tumors irradiated to >5,300 cGy in standard fractionation. Results: The median follow-up was 17.4 months (range, 2.1-47.3). Eighteen sarcomas, seven chordomas, and two ependymomas were treated. The median dose to the planning target volume was 6,600 cGy (range, 5,396-7,080) in 180- or 200-cGy fractions. The median planning target volume was 164 cm{sup 3} (range, 29-1,116). Seven patients developed recurrence at the treatment site (26%), and 6 of these patients had high-grade tumors. Three patients with recurrence had metastatic disease at the time of radiotherapy. The 2-year local control rate was 65%, and the 2-year overall survival rate was 79%. Of the 5 patients who died, 4 had metastatic disease at death. Twenty-three patients (84%) reported either no pain or improved pain at the last follow-up visit. Sixteen patients discontinued narcotic use after treatment (62.5%). Twenty-three patients (89%) had a stable or improved American Spine Injury Association score at the last follow-up visit. No patient experienced radiation-induced myelopathy. Conclusions: The dose to paraspinal tumors has traditionally been limited to respect cord tolerance. With image-guided intensity-modulated radiotherapy, greater doses of radiation delivered in multiple fractions can be prescribed with excellent target coverage, effective palliation, and acceptable toxicity and local control.

  17. Chest Reirradiation With External Beam Radiotherapy for Locally Recurrent Non-Small-Cell Lung Cancer: A Review

    SciTech Connect

    Jeremic, Branislav; Videtic, Gregory M.M.

    2011-07-15

    appropriately characterize the historic practice relevant to thoracic reirradiation of recurrent lung cancer, we carried out a comprehensive search of the English-language literature to identify and review relevant studies of the use of EBRT in the treatment of locally recurrent cancer. We limited our scope to treatment of NSCLC and excluded other RT modalities such as brachytherapy and stereotactic body radiotherapy (SBRT). The goal of this systematic review was to better inform current practice in order to ultimately generate appropriate future research endeavors in this setting.

  18. The Natural History and Predictors of Outcome Following Biochemical Relapse in the Dose Escalation Era for Prostate Cancer Patients Undergoing Definitive External Beam Radiotherapy

    PubMed Central

    Zumsteg, Zachary S.; Spratt, Daniel E.; Romesser, Paul B.; Pei, Xin; Zhang, Zhigang; Polkinghorn, William; McBride, Sean; Kollmeier, Marisa; Yamada, Yoshiya; Zelefsky, Michael J.

    2016-01-01

    Background The management of biochemical failure (BF) following external beam radiotherapy (EBRT) for prostate cancer is controversial, due to both the heterogeneous disease course following a BF and a lack of clinical trials in this setting. Objective We sought to characterize the natural history and predictors of outcome for patients experiencing BF in a large cohort of men with localized prostate cancer undergoing definitive dose-escalated EBRT. Design, setting, and participants This retrospective analysis included 2694 patients with localized prostate cancer treated with EBRT at a large academic center. Of these, 609 experienced BF, defined as prostate-specific antigen (PSA) nadir + 2 ng/ml. The median follow-up was 83 mo for all patients and 122 mo for BF patients. Intervention(s) All patients received EBRT at doses of 75.6–86.4 Gy. Outcome measurements and statistical analysis The primary objective of this study was to determine predictors of distant progression at the time of BF. Cox proportional hazards models were used in univariate and multivariate analyses of distant metastases (DM), and a competing risks method was used to analyze prostate cancer–specific mortality (PCSM). Results and limitations From the date of BF, the median times to DM and PCSM mortality were 5.4 yr and 10.5 yr, respectively. Shorter posttreatment PSA doubling time, a higher initial clinical tumor stage, a higher pretreatment Gleason score, and a shorter interval from the end of radiotherapy to BF were independent predictors for clinical progression following BF. Patients with two of these risk factors had a significantly higher incidence of DM and PCSM following BF than those with zero or one risk factor. The main limitations of this study are its retrospective nature and heterogeneous salvage interventions. Conclusions Clinical and pathologic factors can help identify patients at high risk of clinical progression following BF. Patient summary In this report, we look at

  19. Radiotherapy of Cervical Cancer.

    PubMed

    Vordermark, Dirk

    2016-01-01

    Curative-intent radical radiotherapy of cervical cancer consists of external-beam radiotherapy, brachytherapy, and concomitant chemotherapy with cisplatin. For each element, new developments aim to improve tumor control rates or treatment tolerance. Intensity-modulated radiotherapy (IMRT) has been shown to reduce gastrointestinal toxicity and can be used to selectively increase the radiotherapy dose. Individualized, image-guided brachytherapy enables better adaptation of high-dose volumes to the tumor extension. Intensification of concomitant or sequential systemic therapy is under evaluation. PMID:27614991

  20. Serial megavoltage CT imaging during external beam radiotherapy for non-small-cell lung cancer: Observations on tumor regression during treatment

    SciTech Connect

    Kupelian, Patrick A. . E-mail: kupelian@orhs.org; Ramsey, Chester; Meeks, Sanford L.; Willoughby, Twyla R.; Forbes, Alan; Wagner, Thomas H.; Langen, Katja M.

    2005-11-15

    Purpose: The ability to obtain soft-tissue imaging in the treatment room, such as with megavoltage CT imaging, enables the observation of tumor regression during a course of external beam radiation therapy. In this current study, we report on the most extensive study looking at the rate of regression of non-small-cell lung cancers during a course of external beam radiotherapy by analyzing serial megavoltage CT images obtained on 10 patients. Methods and Materials: The analysis is performed on 10 patients treated with the Helical Tomotherapy Hi*Art device. All 10 patients had non-small-cell lung cancer. A total of 274 megavoltage CT sets were obtained on the 10 patients (average, 27 scans per patient; range, 9-35). All patients had at least a scan at beginning and at the end of treatment. The frequency of scanning was determined by the treating physician. The treatment was subsequently delivered with the Tomotherapy Hi*Art system. The gross tumor volumes (GTVs) were later contoured on each megavoltage CT scan, and tumor volumes were calculated. Although some patients were treated to draining nodal areas in addition to the primary tumor, only the primary GTVs were tracked. Response to treatment was quantified by the relative decrease in tumor volume over time, i.e., elapsed days from the first day of therapy. The individual GTVs ranged from 5.9 to 737.2 cc in volume at the start of treatment. In 6 of the 10 patients, dose recalculations were also performed to document potential variations in delivered doses within the tumors. The megavoltage CT scans were used, and the planned treatment was recalculated on the daily images. The hypothesis was that dose deposited in the target would increase throughout the course of radiotherapy because of tumor shrinkage and subsequent decreasing attenuation. Specifically, the dose received by 95% of the GTV (D{sub 95}) was monitored over time for each of the 6 patients treated at M.D. Anderson Cancer Center Orlando. Results

  1. Report of the AAPM Task Group No. 105: Issues associated with clinical implementation of Monte Carlo-based photon and electron external beam treatment planning

    SciTech Connect

    Chetty, Indrin J.; Curran, Bruce; Cygler, Joanna E.; DeMarco, John J.; Ezzell, Gary; Faddegon, Bruce A.; Kawrakow, Iwan; Keall, Paul J.; Liu, Helen; Ma, C.-M. Charlie; Rogers, D. W. O.; Seuntjens, Jan; Sheikh-Bagheri, Daryoush; Siebers, Jeffrey V.

    2007-12-15

    The Monte Carlo (MC) method has been shown through many research studies to calculate accurate dose distributions for clinical radiotherapy, particularly in heterogeneous patient tissues where the effects of electron transport cannot be accurately handled with conventional, deterministic dose algorithms. Despite its proven accuracy and the potential for improved dose distributions to influence treatment outcomes, the long calculation times previously associated with MC simulation rendered this method impractical for routine clinical treatment planning. However, the development of faster codes optimized for radiotherapy calculations and improvements in computer processor technology have substantially reduced calculation times to, in some instances, within minutes on a single processor. These advances have motivated several major treatment planning system vendors to embark upon the path of MC techniques. Several commercial vendors have already released or are currently in the process of releasing MC algorithms for photon and/or electron beam treatment planning. Consequently, the accessibility and use of MC treatment planning algorithms may well become widespread in the radiotherapy community. With MC simulation, dose is computed stochastically using first principles; this method is therefore quite different from conventional dose algorithms. Issues such as statistical uncertainties, the use of variance reduction techniques, the ability to account for geometric details in the accelerator treatment head simulation, and other features, are all unique components of a MC treatment planning algorithm. Successful implementation by the clinical physicist of such a system will require an understanding of the basic principles of MC techniques. The purpose of this report, while providing education and review on the use of MC simulation in radiotherapy planning, is to set out, for both users and developers, the salient issues associated with clinical implementation and

  2. Postoperative Intensity-Modulated Radiotherapy for Squamous Cell Carcinoma of the External Auditory Canal and Middle Ear: Treatment Outcomes, Marginal Misses, and Perspective on Target Delineation

    SciTech Connect

    Chen, Wan-Yu; Kuo, Sung-Hsin; Chen, Yu-Hsuan; Lu, Szu-Huai; Tsai, Chiao-Ling; Chia-Hsien Cheng, Jason; Hong, Ruey-Long; Chen, Ya-Fang; Hsu, Chuan-Jen; Lin, Kai-Nan; Ko, Jenq-Yuh; Lou, Pei-Jen; Wang, Cheng-Ping; Chong, Fok-Ching; Wang, Chun-Wei

    2012-03-15

    Purpose: To report outcomes of the rare disease of squamous cell carcinoma (SCC) of the external auditory canal (EAC) and middle ear treated with surgery and postoperative intensity-modulated radiotherapy (IMRT). Failure patterns related to spatial dose distribution were also analyzed to provide insight into target delineation. Methods and Materials: A retrospective review was conducted of the records of 11 consecutive patients with SCC of the EAC and middle ear who were treated with curative surgery and postoperative IMRT at one institution between January 2007 and February 2010. The prescribed IMRT dose was 60 to 66 Gy at 2 Gy per fraction. Three patients also received concurrent cisplatin-based chemotherapy, and 1 patient received concurrent oral tegafur/uracil. The median follow-up time was 19 months (range, 6-33 months). Results: Four patients had locoregional recurrence, yielding an estimated 2-year locoregional control rate of 70.7%. Among them, 1 patient had persistent disease after treatment, and 3 had marginal recurrence. Distant metastasis occurred in 1 patient after extensive locoregional recurrence, yielding an estimated 2-year distant control rate of 85.7%. The estimated 2-year overall survival was 67.5%. The three cases of marginal recurrence were near the preauricular space and glenoid fossa of the temporomandibular joint, adjacent to the apex of the ear canal and glenoid fossa of the temporomandibular joint, and in the postauricular subcutaneous area and ipsilateral parotid nodes, respectively. Conclusions: Marginal misses should be recognized to improve target delineation. When treating SCC of the EAC and middle ear, care should be taken to cover the glenoid fossa of the temporomandibular joint and periauricular soft tissue. Elective ipsilateral parotid irradiation should be considered. The treatment planning procedure should also be refined to balance subcutaneous soft-tissue dosimetry and toxicity.

  3. High-Dose-Rate Brachytherapy and External-Beam Radiotherapy for Hormone-Naieve Low- and Intermediate-Risk Prostate Cancer: A 7-Year Experience

    SciTech Connect

    Aluwini, Shafak; Rooij, Peter H. van; Kirkels, Wim J.; Jansen, Peter P.; Praag, John O.; Bangma, Chris H.; Kolkman-Deurloo, Inger-Karine K.

    2012-08-01

    Purpose: To report clinical outcomes and early and late complications in 264 hormone-naieve patients with low- and intermediate-risk prostate cancer treated with high-dose-rate brachytherapy (HDR-BT) in combination with external-beam radiotherapy (EBRT). Methods and Materials: Between February 2000 and July 2007, 264 patients underwent HDR-BT in combination with EBRT as a treatment for their low- to intermediate-risk prostate cancer. The HDR-BT was performed using ultrasound-based implantation. The total HDR-BT dose was 18 Gy in 3 fractions within 24 h, with a 6-h minimum interval. The EBRT started 2 weeks after HDR-BT and was delivered in 25 fractions of 1.8 Gy to 45 Gy within 5 weeks. Results: After a mean follow-up of 74.5 months, 4 patients (1.5%) showed prostate-specific antigen progression according to the American Society for Radiation Oncology definition and 8 patients (3%) according to the Phoenix definition. A biopsy-proven local recurrence was registered in 1 patient (0.4%), and clinical progression (bone metastases) was documented in 2 patients (0.7%). Seven-year actuarial freedom from biochemical failure was 97%, and 7-year disease-specific survival and overall survival were 100% and 91%, respectively. Toxicities were comparable to other series. Conclusions: Treatment with interstitial HDR-BT plus EBRT shows a low incidence of late complications and a favorable oncologic outcome after 7 years follow-up.

  4. Detection of Local, Regional, and Distant Recurrence in Patients With PSA Relapse After External-Beam Radiotherapy Using {sup 11}C-Choline Positron Emission Tomography

    SciTech Connect

    Breeuwsma, Anthonius J.; Pruim, Jan; Bergh, Alphons C.M. van den; Leliveld, Anna M.; Nijman, Rien J.M.; Dierckx, Rudi A.J.O.; Jong, Igle J. de

    2010-05-01

    Purpose: An elevated serum prostate-specific antigen (PSA) level cannot distinguish between local-regional recurrences and the presence of distant metastases after treatment with curative intent for prostate cancer. With the advent of salvage treatment such as cryotherapy, it has become important to localize the site of recurrence (local or distant). In this study, the potential of {sup 11}C-choline positron emission tomography (PET) to identify site of recurrence was investigated in patients with rising PSA after external-beam radiotherapy (EBRT). Methods and Materials: Seventy patients with histologically proven prostate cancer treated with EBRT and showing biochemical recurrence as defined by American Society for Therapeutic Radiology and Oncology consensus statement and 10 patients without recurrence underwent a PET scan using 400 MBq {sup 11}C-choline intravenously. Biopsy-proven histology from the site of suspicion, findings with other imaging modalities, clinical follow-up and/or response to adjuvant therapy were used as comparative references. Results: None of the 10 patients without biochemical recurrence had a positive PET scan. Fifty-seven of 70 patients with biochemical recurrence (median PSA 9.1 ng/mL; mean PSA 12.3 ng/mL) showed an abnormal uptake pattern (sensitivity 81%). The site of recurrence was only local in 41 of 57 patients (mean PSA 11.1 ng/mL at scan), locoregionally and/or distant in 16 of 57 patients (mean PSA 17.7 ng/mL). Overall the positive predictive value and negative predictive value for {sup 11}C-choline PET scan were 1.0 and 0.44 respectively. Accuracy was 84%. Conclusions: {sup 11}C-choline PET scan is a sensitive technique to identify the site of recurrence in patients with PSA relapse after EBRT for prostate cancer.

  5. Impact of External Beam Adjuvant Radiotherapy on Health-Related Quality of Life for Long-Term Survivors of Endometrial Adenocarcinoma: A Population-Based Study

    SciTech Connect

    Poll-Franse, Lonneke V. van de; Essink-Bot, Marie-Louise; Vingerhoets, Ad J.J.M.; Lybeert, Marnix L.M.; Berg, Hetty A. van den; Coebergh, Jan Willem W.

    2007-09-01

    Purpose: To compare the health-related quality of life (HRQOL) among 5-10-year survivors of Stage I-II endometrial (adeno-)carcinoma (EC) treated with surgery alone or surgery with external beam adjuvant radiotherapy (EBRT) and an age-matched norm population. Methods and Materials: A population-based, cross-sectional survey was conducted by the Eindhoven Cancer Registry. All patients were included who had been diagnosed with EC between 1994 and 1998 (n = 462). Information from the questionnaires returned was linked to data from the Eindhoven Cancer Registry on patient, tumor, and treatment characteristics. Results: Responses were received from 75% of the patients. The analyses were restricted to women with Stage I-II disease at diagnosis, treated with either surgery alone or surgery with adjuvant EBRT, and without recurrent disease or new primary malignancies (n = 264). The patients who had received adjuvant EBRT (n = 80) had had a significantly higher tumor stage and grade at diagnosis (p < 0.0001) and a longer mean time since diagnosis (p = 0.04). Age, number of comorbid diseases, current marital status, nulliparity, education, and occupation were similar for both treatment groups. On multivariate analyses, adjuvant EBRT was independently and negatively associated with the vitality and physical and social well-being scale scores. The HRQOL scores of both treatment groups, however, were similar to those of an age-matched norm population. Conclusion: In general, the HRQOL of EC survivors is good. EC survivors treated with surgery alone had a better HRQOL than women treated with surgery and adjuvant EBRT, although for both groups, the HRQOL was in the range of the norm population.

  6. Role of External Beam Radiotherapy in Patients With Advanced or Recurrent Nonanaplastic Thyroid Cancer: Memorial Sloan-Kettering Cancer Center Experience

    SciTech Connect

    Terezakis, Stephanie A. Lee, Kyungmouk S.; Ghossein, Ronald A.; Rivera, Michael; Tuttle, Robert M.; Wolden, Suzanne L.; Zelefsky, Michael J.; Wong, Richard J.; Patel, Snehal G.; Pfister, David G.; Shaha, Ashok R.; Lee, Nancy Y.

    2009-03-01

    Purpose: External beam radiotherapy (EBRT) plays a controversial role in the management of nonanaplastic thyroid cancer. We reviewed our institution's outcomes in patients treated with EBRT for advanced or recurrent nonanaplastic thyroid cancer. Methods and Materials: Between April 1989 and April 2006, 76 patients with nonanaplastic thyroid cancer were treated with EBRT. The median follow-up for the surviving patients was 35.3 months (range, 4.2-178.4). The lesions were primarily advanced and included Stage T2 in 5 (7%), T3 in 5 (7%), and T4 in 64 (84%) patients. Stage N1 disease was present in 60 patients (79%). Distant metastases before EBRT were identified in 27 patients (36%). The median total EBRT dose delivered was 6,300 cGy. The histologic features examined included medullary in 12 patients (16%) and nonmedullary in 64 (84%). Of the 76 patients, 71 (93%) had undergone surgery before RT, and radioactive iodine treatment was used in 56 patients (74%). Results: The 2- and 4-year overall locoregional control rate for all histologic types was 86% and 72%, respectively, and the 2- and 4-year overall survival rate for all patients was 74% and 55%, respectively. No significant differences were found in locoregional control, overall survival, or distant metastases-free survival for patients with complete resection, microscopic residual disease, or gross residual disease. Grade 3 acute mucositis and dysphagia occurred in 14 (18%) and 24 (32%) patients, respectively. Late adverse toxicity was notable for percutaneous endoscopic gastrostomy tube use in 4 patients (5%). Conclusion: The results of our study have shown that EBRT is effective for locoregional control of selected locally advanced or recurrent nonanaplastic thyroid malignancies, with acceptable acute toxicity.

  7. Development of Late Toxicity and International Prostate Symptom Score Resolution After External-Beam Radiotherapy Combined With Pulsed Dose Rate Brachytherapy for Prostate Cancer

    SciTech Connect

    Pieters, Bradley R.; Rezaie, Elisa; Geijsen, Elisabeth D.; Koedooder, Kees; Grient, Johan N.B. van der; Blank, Leo E.C.M.; Reijke, Theo M. de; Koning, Caro C.E.

    2011-11-01

    Purpose: To investigate the development of gastrointestinal (GI) toxicity, genitourinary (GU) toxicity, erectile dysfunction, and International Prostate Symptom Score (IPSS) resolution in a cohort of patients treated with external-beam radiotherapy (EBRT) followed by a brachytherapy pulsed dose rate (PDR) boost. Methods and Materials: Between 2002 and 2008, 110 patients were treated with 46-Gy EBRT followed by PDR brachytherapy (24.96-28.80 Gy). The investigated outcome variables, GI toxicity, GU toxicity, erectile dysfunction, and IPSS were prospectively scored at several time points during follow-up. Association between time (as continuous and categorical variable) and the outcome variables was assessed using generalized linear models. Results: No statistically significant association was found between time (continuous) and GI toxicity (odds ratio [OR], 0.97; 95% confidence interval [CI], 0.89-1.06), GU toxicity (OR, 0.97; 95% CI, 0.91-1.03), erectile dysfunction (OR, 1.06; 95% CI, 0.99-1.11), and IPSS (-0.11; 95% CI, -0.41-0.20). Also, no statistically significant association was found between these variables and time as a categorical variable. GU toxicity was associated with IPSS resolution (OR, 1.16; 95% CI, 1.09-1.24). Posttreatment IPSS was associated with pretreatment IPSS (0.52; 95% CI, 0.25-0.79). Conclusions: No accumulation of high-grade toxicity over time could be established for a group of patients treated with EBRT and PDR brachytherapy for prostate cancer, probably because high-grade late toxicity resolves with time. Also, differences in IPSS values among patients are smaller after treatment than before treatment.

  8. Dose-Volume Parameters of the Corpora Cavernosa Do Not Correlate With Erectile Dysfunction After External Beam Radiotherapy for Prostate Cancer: Results From a Dose-Escalation Trial

    SciTech Connect

    Wielen, Gerard J. van der Hoogeman, Mischa S.; Dohle, Gert R.; Putten, Wim L.J. van; Incrocci, Luca

    2008-07-01

    Purpose: To analyze the correlation between dose-volume parameters of the corpora cavernosa and erectile dysfunction (ED) after external beam radiotherapy (EBRT) for prostate cancer. Methods and Materials: Between June 1997 and February 2003, a randomized dose-escalation trial comparing 68 Gy and 78 Gy was conducted. Patients at our institute were asked to participate in an additional part of the trial evaluating sexual function. After exclusion of patients with less than 2 years of follow-up, ED at baseline, or treatment with hormonal therapy, 96 patients were eligible. The proximal corpora cavernosa (crura), the superiormost 1-cm segment of the crura, and the penile bulb were contoured on the planning computed tomography scan and dose-volume parameters were calculated. Results: Two years after EBRT, 35 of the 96 patients had developed ED. No statistically significant correlations between ED 2 years after EBRT and dose-volume parameters of the crura, the superiormost 1-cm segment of the crura, or the penile bulb were found. The few patients using potency aids typically indicated to have ED. Conclusion: No correlation was found between ED after EBRT for prostate cancer and radiation dose to the crura or penile bulb. The present study is the largest study evaluating the correlation between ED and radiation dose to the corpora cavernosa after EBRT for prostate cancer. Until there is clear evidence that sparing the penile bulb or crura will reduce ED after EBRT, we advise to be careful in sparing these structures, especially when this involves reducing treatment margins.

  9. Randomized Control Trial: Evaluating Aluminum-Based Antiperspirant Use, Axilla Skin Toxicity, and Reported Quality of Life in Women Receiving External Beam Radiotherapy for Treatment of Stage 0, I, and II Breast Cancer

    SciTech Connect

    Watson, Linda C.; Gies, Donna; Thompson, Emmanuel; Thomas, Bejoy

    2012-05-01

    Purpose: Standard skin care instructions regarding the use of antiperspirants during radiotherapy to the breast varies across North America. Women have articulated that when instructed to not use antiperspirant, the potential for body odor is distressing. Historical practices and individual opinions have often guided practice in this field. The present study had 2 purposes. To evaluate whether the use of aluminum-based antiperspirant while receiving external beam radiotherapy for stage 0, I, or II breast cancer will increase axilla skin toxicity and to evaluate whether the use of antiperspirant during external beam radiotherapy improves quality of life. Methods: A total of 198 participants were randomized to either the experimental group (antiperspirant) or control group (standard care-wash only). The skin reactions in both groups were measured weekly and 2 weeks after treatment using the National Cancer Institute Common Toxicity Criteria Adverse Events, version 3, toxicity grading criteria. Both groups completed the Functional Assessment for Chronic Illness Therapy's questionnaire for the breast population quality of life assessment tool, with additional questions evaluating the effect of underarm antiperspirant use on quality of life before treatment, immediately after treatment, and 2 weeks after treatment during the study. Results: The skin reaction data were analyzed using the generalized estimating equation. No statistically significant difference was seen in the skin reaction between the 2 groups over time. The quality of life data also revealed no statistically significant difference between the 2 groups over time. Conclusions: Data analysis indicates that using antiperspirant routinely during external beam radiotherapy for Stage 0, I, or II breast cancer does not affect the intensity of the skin reaction or the self-reported quality of life. This evidence supports that in this particular population, there is no purpose to restrict these women from using

  10. Quality control of the TSV multi-pixel photon counter arrays, and modules for the external plate of EndoTOF-PET ultrasound detector

    NASA Astrophysics Data System (ADS)

    Liu, Z.; Doroud, K.; Auffray, E.; Ben Mimoun Bel Hadj, F.; Cortinovis, D.; Garutti, E.; Lecoq, P.; Paganoni, M.; Pizzichemi, M.; Silenzi, A.; Xu, C.; Zvolsky, M.

    2015-07-01

    The aim of the EndoTOFPET-US collaboration is to develop a multi-modal imaging tool combining ultrasound with time-of-flight positron emission tomography into an endoscopic imaging device. One of the objectives of this scanner is to reach a coincidence time resolution of 200 ps full width at half maximum. The external detector is constructed with 256 matrices of 4×4 lutetium-yttrium oxyorthosilicate scintillating crystals, each with a size of 3.5 × 3.5 × 15mm3, coupled to 256 Hamamatsu TSV multi-pixel photon counter arrays (S12643-050CN). A full characterisation of these arrays has been performed in order to assure the quality of the arrays prior to the gluing to the crystal matrices. The breakdown voltage, dark count rate and single photon time resolution have been measured both at DESY and CERN. After this characterisation, the crystal matrices were glued to the multi-pixel photon counter arrays. The coincidence time resolution of each module has been measured at CERN using an ultra-fast amplifier-discriminator as the reference readout ASIC. Results of the characterisation of multi-pixel photon counter arrays and the crystal modules are presented here.

  11. Retinoblastoma external beam photon irradiation with a special ‘D’-shaped collimator: a comparison between measurements, Monte Carlo simulation and a treatment planning system calculation

    NASA Astrophysics Data System (ADS)

    Brualla, L.; Mayorga, P. A.; Flühs, A.; Lallena, A. M.; Sempau, J.; Sauerwein, W.

    2012-11-01

    Retinoblastoma is the most common eye tumour in childhood. According to the available long-term data, the best outcome regarding tumour control and visual function has been reached by external beam radiotherapy. The benefits of the treatment are, however, jeopardized by a high incidence of radiation-induced secondary malignancies and the fact that irradiated bones grow asymmetrically. In order to better exploit the advantages of external beam radiotherapy, it is necessary to improve current techniques by reducing the irradiated volume and minimizing the dose to the facial bones. To this end, dose measurements and simulated data in a water phantom are essential. A Varian Clinac 2100 C/D operating at 6 MV is used in conjunction with a dedicated collimator for the retinoblastoma treatment. This collimator conforms a ‘D’-shaped off-axis field whose irradiated area can be either 5.2 or 3.1 cm2. Depth dose distributions and lateral profiles were experimentally measured. Experimental results were compared with Monte Carlo simulations’ run with the penelope code and with calculations performed with the analytical anisotropic algorithm implemented in the Eclipse treatment planning system using the gamma test. penelope simulations agree reasonably well with the experimental data with discrepancies in the dose profiles less than 3 mm of distance to agreement and 3% of dose. Discrepancies between the results found with the analytical anisotropic algorithm and the experimental data reach 3 mm and 6%. Although the discrepancies between the results obtained with the analytical anisotropic algorithm and the experimental data are notable, it is possible to consider this algorithm for routine treatment planning of retinoblastoma patients, provided the limitations of the algorithm are known and taken into account by the medical physicist and the clinician. Monte Carlo simulation is essential for knowing these limitations. Monte Carlo simulation is required for optimizing the

  12. [Radiotherapy for Thyroid Cancer].

    PubMed

    Jingu, Keiichi; Maruoka, Shin; Umezawa, Rei; Takahashi, Noriyoshi

    2015-06-01

    Radioactive 131I therapy for differentiated thyroid cancer has been used since the 1940s and is an established and effective treatment. In contrast, external beam radiotherapy (EBRT) was considered to be effective for achieving local control but not for prolonging survival. Although clinicians were hesitant to administer EBRT owing to the potential radiation-induced adverse effects of 2 dimensional (2D)-radiotherapy until 2000, it is expected that adverse effects will be reduced and treatment efficacy improved through the introduction of more advanced techniques for delivering radiation (eg, 3D-radiotherapy and intensity modulated radiotherapy [IMRT]). The prognosis of undifferentiated thyroid cancer is known to be extremely bad, although in very rare cases, multimodality therapy (total or subtotal resection, chemotherapy, and radiotherapy) has allowed long-term survival. Here, we report the preliminary results of using hypofractionated radiotherapy for undifferentiated thyroid cancer in our institution. PMID:26199238

  13. Dosimetric Comparison of Involved-Field Three-Dimensional Conformal Photon Radiotherapy and Breast-Sparing Proton Therapy for the Treatment of Hodgkin's Lymphoma in Female Pediatric Patients

    SciTech Connect

    Andolino, David L.; Hoene, Ted; Xiao, Lu; Buchsbaum, Jeffrey; Chang, Andrew L.

    2011-11-15

    Purpose: To assess the potential reduction in breast dose for young girls with Hodgkin's lymphoma (HL) treated with breast-sparing proton therapy (BS-PT) as compared with three-dimensional conformal involved-field photon radiotherapy (3D-CRT). Methods and Materials: The Clarian Health Cancer Registry was queried for female pediatric patients with the diagnosis of HL who received radiotherapy at the Indiana University Simon Cancer Center during 2006-2009. The original CT simulation images were obtained, and 3D-CRT and BS-PT plans delivering 21 Gy or cobalt gray equivalent (CGE) in 14 fractions were created for each patient. Dose-volume histogram data were collected for both 3D-CRT and BS-PT plans and compared by paired t test for correlated samples. Results: The cancer registry provided 10 female patients with Ann Arbor Stage II HL, aged 10-18 years at the time of treatment. Both mean and maximum breast dose were significantly less with BS-PT compared with 3D-CRT: 0.95 CGE vs. 4.70 Gy (p < 0.001) and 21.07 CGE vs. 23.11 Gy (p < 0.001), respectively. The volume of breast receiving 1.0 Gy/CGE and 5.0 Gy/CGE was also significantly less with BS-PT, 194 cm{sup 3} and 93 cm{sup 3}, respectively, compared with 790 cm{sup 3} and 360 cm{sup 3} with 3D-CRT (p = 0.009, 0.013). Conclusion: Breast-sparing proton therapy has the potential to reduce unnecessary breast dose in young girls with HL by as much as 80% relative to involved-field 3D-CRT.

  14. Widely tunable eye-safe laser by a passively Q-switched photonic crystal fiber laser and an external-cavity optical parametric oscillator

    NASA Astrophysics Data System (ADS)

    Chang, H. L.; Zhuang, W. Z.; Huang, W. C.; Huang, J. Y.; Huang, K. F.; Chen, Y. F.

    2011-09-01

    We report on a widely tunable passively Q-switched photonic crystal fiber (PCF) laser with wavelength tuning range up to 80 nm. The PCF laser utilizes an AlGaInAs quantum well/barrier structure as a saturable absorber and incorporates an external-cavity optical parametric oscillator (OPO) to achieve wavelength conversion. Under a pump power of 13.1 W at 976 nm, the PCF laser generated 1029-nm radiation with maximum output energy of 750 μJ and was incident into an external-cavity OPO. The output energy and peak power of signal wave was found to be 138 μJ and 19 kW, respectively. By tuning the temperature of nonlinear crystal, periodically poled lithium niobate (PPLN), in the OPO, the signal wavelength in eye-safe regime from 1513 to 1593 nm was obtained.

  15. 2D mapping of the MV photon fluence and 3D dose reconstruction in real time for quality assurance during radiotherapy treatment

    NASA Astrophysics Data System (ADS)

    Alrowaili, Z. A.; Lerch, M. L. F.; Carolan, M.; Fuduli, I.; Porumb, C.; Petasecca, M.; Metcalfe, P.; Rosenfeld, A. B.

    2015-09-01

    Summary: the photon irradiation response of a 2D solid state transmission detector array mounted in a linac block tray is used to reconstruct the projected 2D dose map in a homogenous phantom along rays that diverge from the X-ray source and pass through each of the 121 detector elements. A unique diode response-to-dose scaling factor, applied to all detectors, is utilised in the reconstruction to demonstrate that real time QA during radiotherapy treatment is feasible. Purpose: to quantitatively demonstrate reconstruction of the real time radiation dose from the irradiation response of the 11×11 silicon Magic Plate (MP) detector array operated in Transmission Mode (MPTM). Methods and Materials: in transmission mode the MP is positioned in the block tray of a linac so that the central detector of the array lies on the central axis of the radiation beam. This central detector is used to determine the conversion factor from measured irradiation response to reconstructed dose at any point on the central axis within a homogenous solid water phantom. The same unique conversion factor is used for all MP detector elements lying within the irradiation field. Using the two sets of data, the 2D or 3D dose map is able to be reconstructed in the homogenous phantom. The technique we have developed is illustrated here for different depths and irradiation field sizes, (5 × 5 cm2 to 40 × 40 cm2) as well as a highly non uniform irradiation field. Results: we find that the MPTM response is proportional to the projected 2D dose map measured at a specific phantom depth, the "sweet depth". A single factor, for several irradiation field sizes and depths, is derived to reconstruct the dose in the phantom along rays projected from the photon source through each MPTM detector element. We demonstrate that for all field sizes using the above method, the 2D reconstructed and measured doses agree to within ± 2.48% (2 standard deviation) for all in-field MP detector elements. Conclusions: a

  16. Threshold intensity and coefficient of raman scattering amplification in a high- Q bilayer microresonator during the formation of internal and external submicron photonic jets: A photonic nanojet in the near field

    NASA Astrophysics Data System (ADS)

    Zhuravlev, M. V.; Solis, N. W.; Peretyagin, P. Yu.; Okun'kova, A. A.; Torrecillas, R.

    2016-04-01

    Using quantum and semiclassical approaches, the energy excitation threshold for induced Raman scattering is estimated and a relationship between the excitation threshold and the concentration of optically active molecules in a bilayer microresonator is established. Estimates are made during the formation of specially configured optical fields: internal and external photonic nanojets. Based on the amount of stored energy per mode and the value of the threshold intensity, an additional generalized selection rule for whispering gallery modes is suggested. It is shown that the bilayer microresonator can focus incident radiation (laser pumping) into a submicron focal volume at a low threshold intensity.

  17. Prognostic Significance of 5-Year PSA Value for Predicting Prostate Cancer Recurrence After Brachytherapy Alone and Combined With Hormonal Therapy and/or External Beam Radiotherapy

    SciTech Connect

    Stock, Richard G. Klein, Thomas J.; Cesaretti, Jamie A.; Stone, Nelson N.

    2009-07-01

    Purpose: To analyze the prognosis and outcomes of patients who remain free of biochemical failure during the first 5 years after treatment. Methods and Materials: Between 1991 and 2002, 742 patients with prostate cancer were treated with brachytherapy alone (n = 306), brachytherapy and hormonal therapy (n = 212), or combined implantation and external beam radiotherapy (with or without hormonal therapy; n = 224). These patients were free of biochemical failure (American Society for Therapeutic Radiology and Oncology [ASTRO] definition) during the first 5 post-treatment years and had a documented 5-year prostate-specific antigen (PSA) value. The median follow-up was 6.93 years. Results: The actuarial 10-year freedom from PSA failure rate was 97% using the ASTRO definition and 95% using the Phoenix definition. The median 5-year PSA level was 0.03 ng/mL (range, 0-3.6). The 5-year PSA value was {<=}0.01 in 47.7%, >0.01-0.10 in 31.1%, >0.10-0.2 in 10.2%, >0.2-0.5 in 7.82%, and >0.5 in 3.10%. The 5-year PSA value had prognostic significance, with a PSA value of {<=}0.2 ng/mL (n = 661) corresponding to a 10-year freedom from PSA failure rate of 99% with the ASTRO definition and 98% with the Phoenix definition vs. 86% (ASTRO definition) and 81% (Phoenix definition) for a PSA value {>=}0.2 ng/mL (n = 81; p < .0001). The treatment regimen had no effect on biochemical failure. None of the 742 patients in this study developed metastatic disease or died of prostate cancer. Conclusion: The results of this study have shown that the prognosis for patients treated with brachytherapy and who remain biochemically free of disease for {>=}5 years is excellent and none developed metastatic disease during the first 10 years after treatment. The 5-year PSA value is prognostic, and patients with a PSA value <0.2 ng/mL are unlikely to develop subsequent biochemical relapse.

  18. Quality of Life After Whole Pelvic Versus Prostate-Only External Beam Radiotherapy for Prostate Cancer: A Matched-Pair Comparison

    SciTech Connect

    Pinkawa, Michael; Piroth, Marc D.; Holy, Richard; Fischedick, Karin; Klotz, Jens; Szekely-Orban, Dalma; Eble, Michael J.

    2011-09-01

    Purpose: Comparison of health-related quality of life after whole pelvic (WPRT) and prostate-only (PORT) external beam radiotherapy for prostate cancer. Methods and Materials: A group of 120 patients (60 in each group) was surveyed prospectively before radiation therapy (RT) (time A), at the last day of RT (time B), at a median time of 2 months (time C) and >1 year after RT (time D) using a validated questionnaire (Expanded Prostate Cancer Index Composite). All patients were treated with 1.8- to 2.0-Gy fractions up to 70.2 to 72.0 Gy with or without WPRT up to 45 to 46 Gy. Pairs were matched according to the following criteria: age {+-} 5years, planning target volume {+-} 10 cc (considering planning target volume without pelvic nodes for WPRT patients), urinary/bowel/sexual function score before RT {+-} 10, and use of antiandrogens. Results: With the exception of prognostic risk factors, both groups were well balanced with respect to baseline characteristics. No significant differences were found with regard to urinary and sexual score changes. Mean bladder function scores reached baseline levels in both patient subgroups after RT. However, bowel function scores decreased significantly more for patients after WPRT than in those receiving PORT at all times (p < 0.01, respectively). Significant differences were found for most items in the bowel domain in the acute phase. At time D, patients after WPRT reported rectal urgency (>once a day in 15% vs. 3%; p = 0.03), bloody stools ({>=}half the time in 7% vs. 0%; p = 0.04) and frequent bowel movements (>two on a typical day in 32% vs. 7%; p < 0.01) more often than did patients after PORT. Conclusion: In comparison to PORT, WPRT (larger bladder and rectum volumes in medium dose levels, but similar volumes in high dose levels) was associated with decreased bowel quality of life in the acute and chronic phases after treatment but remained without adverse long-term urinary effects.

  19. 20 Gy Versus 44 Gy of Supplemental External Beam Radiotherapy With Palladium-103 for Patients With Greater Risk Disease: Results of a Prospective Randomized Trial

    SciTech Connect

    Merrick, Gregory S.; Butler, Wayne M.; Galbreath, Robert W.; Orio, Peter

    2012-03-01

    Purpose: The necessity of external beam radiotherapy (EBRT) as a supplement to prostate brachytherapy remains unknown. We report brachytherapy outcomes for patients with higher risk features randomized to substantially different supplemental EBRT regimens. Methods and Materials: Between December 1999 and June 2004, 247 patients were randomized to 20 Gy vs. 44 Gy EBRT followed by a palladium-103 boost (115 Gy vs. 90 Gy). The eligibility criteria included clinically organ-confined disease with Gleason score 7-10 and/or pretreatment prostate-specific antigen (PSA) level 10-20 ng/mL. The median follow-up period was 9.0 years. Biochemical progression-free survival (bPFS) was defined as a PSA level of {<=}0.40 ng/mL after nadir. The median day 0 prescribed dose covering 90% of the target volume was 125.7%; 80 men received androgen deprivation therapy (median, 4 months). Multiple parameters were evaluated for their effect on bPFS. Results: For the entire cohort, the cause-specific survival, bPFS, and overall survival rates were 97.7%, 93.2%, and 80.8% at 8 years and 96.9%, 93.2%, and 75.4% at 10 years, respectively. The bPFS rate was 93.1% and 93.4% for the 20-Gy and 44-Gy arms, respectively (p = .994). However, no statistically significant differences were found in cause-specific survival or overall survival were identified. When stratified by PSA level of {<=}10 ng/mL vs. >10 ng/mL, Gleason score, or androgen deprivation therapy, no statistically significant differences in bPFS were discerned between the two EBRT regimens. On multivariate analysis, bPFS was most closely related to the preimplant PSA and clinical stage. For patients with biochemically controlled disease, the median PSA level was <0.02 ng/mL. Conclusion: The results of the present trial strongly suggest that two markedly different supplemental EBRT regimens result in equivalent cause-specific survival, bPFS, and overall survival. It is probable that the lack of benefit for a higher supplemental EBRT dose

  20. Effusive molecular beam-sampled Knudsen flow reactor coupled to vacuum ultraviolet single photon ionization mass spectrometry using an external free radical source

    SciTech Connect

    Leplat, N.; Rossi, M. J.

    2013-11-15

    A new apparatus using vacuum ultraviolet single photon ionization mass spectrometry (VUV SPIMS) of an effusive molecular beam emanating from a Knudsen flow reactor is described. It was designed to study free radical-molecule kinetics over a significant temperature range (300–630 K). Its salient features are: (1) external free radical source, (2) counterpropagating molecular beam and diffuse VUV photon beam meeting in a crossed-beam ion source of a quadrupole mass spectrometer with perpendicular ion extraction, (3) analog detection of the photocurrent of the free radical molecular cation, and (4) possibility of detecting both free radicals and closed shell species in the same apparatus and under identical reaction conditions owing to the presence of photoelectrons generated by the photoelectric effect of the used VUV-photons. The measured thermal molecular beam-to-background ratio was 6.35 ± 0.39 for Ar and 10.86 ± 1.59 for i-C{sub 4}H{sub 10} at 300 K, a factor of 2.52 and 1.50 smaller, respectively, than predicted from basic gas-dynamic considerations. Operating parameters as well as the performance of key elements of the instrument are presented and discussed. Coupled to an external free radical source a steady-state specific exit flow of 1.6 × 10{sup 11} and 5.0 × 10{sup 11} molecule s{sup −1} cm{sup −3} of C{sub 2}H{sub 5}{sup •} (ethyl) and t-C{sub 4}H{sub 9}{sup •} (t-butyl) free radicals have been detected using VUV SPIMS at their molecular ion m/z 29 and 57, respectively, at 300 K.

  1. Effusive molecular beam-sampled Knudsen flow reactor coupled to vacuum ultraviolet single photon ionization mass spectrometry using an external free radical source.

    PubMed

    Leplat, N; Rossi, M J

    2013-11-01

    A new apparatus using vacuum ultraviolet single photon ionization mass spectrometry (VUV SPIMS) of an effusive molecular beam emanating from a Knudsen flow reactor is described. It was designed to study free radical-molecule kinetics over a significant temperature range (300-630 K). Its salient features are: (1) external free radical source, (2) counterpropagating molecular beam and diffuse VUV photon beam meeting in a crossed-beam ion source of a quadrupole mass spectrometer with perpendicular ion extraction, (3) analog detection of the photocurrent of the free radical molecular cation, and (4) possibility of detecting both free radicals and closed shell species in the same apparatus and under identical reaction conditions owing to the presence of photoelectrons generated by the photoelectric effect of the used VUV-photons. The measured thermal molecular beam-to-background ratio was 6.35 ± 0.39 for Ar and 10.86 ± 1.59 for i-C4H10 at 300 K, a factor of 2.52 and 1.50 smaller, respectively, than predicted from basic gas-dynamic considerations. Operating parameters as well as the performance of key elements of the instrument are presented and discussed. Coupled to an external free radical source a steady-state specific exit flow of 1.6 × 10(11) and 5.0 × 10(11) molecule s(-1) cm(-3) of C2H5(●) (ethyl) and t-C4H9(●) (t-butyl) free radicals have been detected using VUV SPIMS at their molecular ion m/z 29 and 57, respectively, at 300 K. PMID:24289411

  2. Methods and computer readable medium for improved radiotherapy dosimetry planning

    DOEpatents

    Wessol, Daniel E.; Frandsen, Michael W.; Wheeler, Floyd J.; Nigg, David W.

    2005-11-15

    Methods and computer readable media are disclosed for ultimately developing a dosimetry plan for a treatment volume irradiated during radiation therapy with a radiation source concentrated internally within a patient or incident from an external beam. The dosimetry plan is available in near "real-time" because of the novel geometric model construction of the treatment volume which in turn allows for rapid calculations to be performed for simulated movements of particles along particle tracks therethrough. The particles are exemplary representations of alpha, beta or gamma emissions emanating from an internal radiation source during various radiotherapies, such as brachytherapy or targeted radionuclide therapy, or they are exemplary representations of high-energy photons, electrons, protons or other ionizing particles incident on the treatment volume from an external source. In a preferred embodiment, a medical image of a treatment volume irradiated during radiotherapy having a plurality of pixels of information is obtained.

  3. Evaluation of PENFAST--a fast Monte Carlo code for dose calculations in photon and electron radiotherapy treatment planning.

    PubMed

    Habib, B; Poumarede, B; Tola, F; Barthe, J

    2010-01-01

    The aim of the present study is to demonstrate the potential of accelerated dose calculations, using the fast Monte Carlo (MC) code referred to as PENFAST, rather than the conventional MC code PENELOPE, without losing accuracy in the computed dose. For this purpose, experimental measurements of dose distributions in homogeneous and inhomogeneous phantoms were compared with simulated results using both PENELOPE and PENFAST. The simulations and experiments were performed using a Saturne 43 linac operated at 12 MV (photons), and at 18 MeV (electrons). Pre-calculated phase space files (PSFs) were used as input data to both the PENELOPE and PENFAST dose simulations. Since depth-dose and dose profile comparisons between simulations and measurements in water were found to be in good agreement (within +/-1% to 1 mm), the PSF calculation is considered to have been validated. In addition, measured dose distributions were compared to simulated results in a set of clinically relevant, inhomogeneous phantoms, consisting of lung and bone heterogeneities in a water tank. In general, the PENFAST results agree to within a 1% to 1 mm difference with those produced by PENELOPE, and to within a 2% to 2 mm difference with measured values. Our study thus provides a pre-clinical validation of the PENFAST code. It also demonstrates that PENFAST provides accurate results for both photon and electron beams, equivalent to those obtained with PENELOPE. CPU time comparisons between both MC codes show that PENFAST is generally about 9-21 times faster than PENELOPE. PMID:19342258

  4. Monitor unit calculations for external photon and electron beams: Report of the AAPM Therapy Physics Committee Task Group No. 71

    SciTech Connect

    Gibbons, John P.; Antolak, John A.; Followill, David S.; Huq, M. Saiful; Klein, Eric E.; Lam, Kwok L.; Palta, Jatinder R.; Roback, Donald M.; Reid, Mark; Khan, Faiz M.

    2014-03-15

    A protocol is presented for the calculation of monitor units (MU) for photon and electron beams, delivered with and without beam modifiers, for constant source-surface distance (SSD) and source-axis distance (SAD) setups. This protocol was written by Task Group 71 of the Therapy Physics Committee of the American Association of Physicists in Medicine (AAPM) and has been formally approved by the AAPM for clinical use. The protocol defines the nomenclature for the dosimetric quantities used in these calculations, along with instructions for their determination and measurement. Calculations are made using the dose per MU under normalization conditions, D{sub 0}{sup ′}, that is determined for each user's photon and electron beams. For electron beams, the depth of normalization is taken to be the depth of maximum dose along the central axis for the same field incident on a water phantom at the same SSD, where D{sub 0}{sup ′} = 1 cGy/MU. For photon beams, this task group recommends that a normalization depth of 10 cm be selected, where an energy-dependent D{sub 0}{sup ′} ≤ 1 cGy/MU is required. This recommendation differs from the more common approach of a normalization depth of d{sub m}, with D{sub 0}{sup ′} = 1 cGy/MU, although both systems are acceptable within the current protocol. For photon beams, the formalism includes the use of blocked fields, physical or dynamic wedges, and (static) multileaf collimation. No formalism is provided for intensity modulated radiation therapy calculations, although some general considerations and a review of current calculation techniques are included. For electron beams, the formalism provides for calculations at the standard and extended SSDs using either an effective SSD or an air-gap correction factor. Example tables and problems are included to illustrate the basic concepts within the presented formalism.

  5. Consistency in reference radiotherapy dosimetry: resolution of an apparent conundrum when 60Co is the reference quality for charged-particle and photon beams

    NASA Astrophysics Data System (ADS)

    Andreo, Pedro; Wulff, Jörg; Burns, David T.; Palmans, Hugo

    2013-10-01

    Substantial changes in ion chamber perturbation correction factors in 60Co γ-rays, suggested by recent Monte Carlo (MC) calculations, would cause a decrease of about 1.5% in the reference dosimetry of all types of charged particles (electrons, protons and heavier ions) based on calculated kQ values. It has gone largely unnoticed that the ratio of calibration coefficients ND, w, Co60 and NK, air, Co60 yields an experimental value of Fch, Co60 = (sw-air pch)Co60 through ND, air, Co60. Coefficients provided by the IAEA and traceable to the BIPM for 91 NE-2571 chambers result in an average Fch, Co60 which is compared with published (and new) MC simulations and with the value in IAEA TRS-398. It is shown that TRS-398 agrees within 0.12% with the experimental Fch, Co60. The 1.5% difference resulting from MC calculations (1.1% for the new simulations) cannot be justified using current fundamental data and BIPM standards if consistency in the entire dosimetry chain is sought. For photons, MC kQ factors are compared with TRS-398. Using the same uncertainty for Wair, the two sets of data overlap considerably. Experimental kQ values from standards laboratories lie between the two sets of calculated values, showing no preference for one set over the other. Observed chamber-to-chamber differences, that include the effect of waterproof sleeves (also seen for 60Co), justify the recommendation in TRS-398 for kQ values specifically measured for the user chamber. Current developments on I-values for the stopping powers of water and graphite are presented. A weighted average Iwater = 78 ± 2 eV is obtained from published experimental and DRF-based values; this would decrease sw-air for all types of radiotherapy beams between 0.3% and 0.6%, and would consequently decrease the MC derived Fch, Co60. The implications of a recent proposal for Igraphite = 81 eV are analysed, resulting in a potential decrease of 0.7% in NK, air, Co60 which would raise the experimental Fch, Co60

  6. Adaptive-Predictive Organ Localization Using Cone-Beam Computed Tomography for Improved Accuracy in External Beam Radiotherapy for Bladder Cancer

    SciTech Connect

    Lalondrelle, Susan; Huddart, Robert; Warren-Oseni, Karole; Hansen, Vibeke Nordmark; McNair, Helen; Thomas, Karen; Dearnaley, David; Horwich, Alan; Khoo, Vincent

    2011-03-01

    Purpose: To examine patterns of bladder wall motion during high-dose hypofractionated bladder radiotherapy and to validate a novel adaptive planning method, A-POLO, to prevent subsequent geographic miss. Methods and Materials: Patterns of individual bladder filling were obtained with repeat computed tomography planning scans at 0, 15, and 30 minutes after voiding. A series of patient-specific plans corresponding to these time-displacement points was created. Pretreatment cone-beam computed tomography was performed before each fraction and assessed retrospectively for adaptive intervention. In fractions that would have required intervention, the most appropriate plan was chosen from the patient's 'library,' and the resulting target coverage was reassessed with repeat cone-beam computed tomography. Results: A large variation in patterns of bladder filling and interfraction displacement was seen. During radiotherapy, predominant translations occurred cranially (maximum 2.5 cm) and anteriorly (maximum 1.75 cm). No apparent explanation was found for this variation using pretreatment patient factors. A need for adaptive planning was demonstrated by 51% of fractions, and 73% of fractions would have been delivered correctly using A-POLO. The adaptive strategy improved target coverage and was able to account for intrafraction motion also. Conclusions: Bladder volume variation will result in geographic miss in a high proportion of delivered bladder radiotherapy treatments. The A-POLO strategy can be used to correct for this and can be implemented from the first fraction of radiotherapy; thus, it is particularly suited to hypofractionated bladder radiotherapy regimens.

  7. Implementation and validation of a fluence pencil kernels model for GaN-based dosimetry in photon beam radiotherapy

    NASA Astrophysics Data System (ADS)

    Wang, Ruoxi; Pittet, Patrick; Ribouton, Julien; Lu, Guo-Neng; Chaikh, Abdulhamid; Ahnesjö, Anders

    2013-10-01

    Gallium nitride (GaN), a direct-gap semiconductor that is radioluminescent, can be used as a transducer yielding a high signal from a small detecting volume and thus potentially suitable for use in small fields and for high dose gradients. A common drawback of semiconductor dosimeters with effective atomic numbers higher than soft tissues is that their responses depend on the presence of low energy photons for which the photoelectric cross section varies strongly with atomic number, which may affect the accuracy of dosimetric measurements. To tackle this ‘over-response’ issue, we propose a model for GaN-based dosimetry with readout correction. The local photon spectrum is calculated by convolving fluence pencil kernel spectra with the beam aperture fluence distribution. The response of a GaN detector is modelled by combining large cavity theory and small cavity theory for the low and high energy components of the local spectrum. Monte Carlo simulations are employed for determination of specific correction factors for different GaN transducer sizes and irradiation conditions. Some model parameters such as the cut-off energy and partitioning energy are discussed. The accuracy of the GaN dosimetric response model has been evaluated for tissue phantom ratio experiments along the central axis. These experiments have shown that calculated and measured GaN responses stay within ±3% at all depths beyond the build-up depth. The calculated GaN response factor is also in good agreement with measured data (±2.5%). The validated model with response compensation improves significantly the accuracy of dosimetric measurements: below 2.5% deviation as compared to 13% without compensation, for a 10 × 10 cm2 field, at depth from 1.5 to 22 cm.

  8. Selected organ dose conversion coefficients for external photons calculated using ICRP adult voxel phantoms and Monte Carlo code FLUKA.

    PubMed

    Patni, H K; Nadar, M Y; Akar, D K; Bhati, S; Sarkar, P K

    2011-11-01

    The adult reference male and female computational voxel phantoms recommended by ICRP are adapted into the Monte Carlo transport code FLUKA. The FLUKA code is then utilised for computation of dose conversion coefficients (DCCs) expressed in absorbed dose per air kerma free-in-air for colon, lungs, stomach wall, breast, gonads, urinary bladder, oesophagus, liver and thyroid due to a broad parallel beam of mono-energetic photons impinging in anterior-posterior and posterior-anterior directions in the energy range of 15 keV-10 MeV. The computed DCCs of colon, lungs, stomach wall and breast are found to be in good agreement with the results published in ICRP publication 110. The present work thus validates the use of FLUKA code in computation of organ DCCs for photons using ICRP adult voxel phantoms. Further, the DCCs for gonads, urinary bladder, oesophagus, liver and thyroid are evaluated and compared with results published in ICRP 74 in the above-mentioned energy range and geometries. Significant differences in DCCs are observed for breast, testis and thyroid above 1 MeV, and for most of the organs at energies below 60 keV in comparison with the results published in ICRP 74. The DCCs of female voxel phantom were found to be higher in comparison with male phantom for almost all organs in both the geometries. PMID:21147784

  9. Monte Carlo study for designing a dedicated “D”-shaped collimator used in the external beam radiotherapy of retinoblastoma patients

    SciTech Connect

    Mayorga, P. A.; Brualla, L.; Sauerwein, W.; Lallena, A. M.

    2014-01-15

    Purpose: Retinoblastoma is the most common intraocular malignancy in the early childhood. Patients treated with external beam radiotherapy respond very well to the treatment. However, owing to the genotype of children suffering hereditary retinoblastoma, the risk of secondary radio-induced malignancies is high. The University Hospital of Essen has successfully treated these patients on a daily basis during nearly 30 years using a dedicated “D”-shaped collimator. The use of this collimator that delivers a highly conformed small radiation field, gives very good results in the control of the primary tumor as well as in preserving visual function, while it avoids the devastating side effects of deformation of midface bones. The purpose of the present paper is to propose a modified version of the “D”-shaped collimator that reduces even further the irradiation field with the scope to reduce as well the risk of radio-induced secondary malignancies. Concurrently, the new dedicated “D”-shaped collimator must be easier to build and at the same time produces dose distributions that only differ on the field size with respect to the dose distributions obtained by the current collimator in use. The scope of the former requirement is to facilitate the employment of the authors' irradiation technique both at the authors' and at other hospitals. The fulfillment of the latter allows the authors to continue using the clinical experience gained in more than 30 years. Methods: The Monte Carlo codePENELOPE was used to study the effect that the different structural elements of the dedicated “D”-shaped collimator have on the absorbed dose distribution. To perform this study, the radiation transport through a Varian Clinac 2100 C/D operating at 6 MV was simulated in order to tally phase-space files which were then used as radiation sources to simulate the considered collimators and the subsequent dose distributions. With the knowledge gained in that study, a new, simpler,

  10. Fractionated beam radiotherapy is a special case of continuous beam radiotherapy when irradiation time is small.

    PubMed

    Biswas, Jayanta; Rajguru, Tapan K; Choudhury, Krishnangshu B; Dutta, Sumita; Sharma, Shyam; Sarkar, Aniruddha

    2013-01-01

    Fractionated beam radiotherapy, in other terms, external beam radiotherapy (EBRT) and continuous beam radiotherapy or Brachytherapy are two modes of radiotherapy techniques. Although in many ways, they appear to be different, radiobiologically, with the help of mathematics, it can be proved that the biological effective dose (BED) of EBRT is similar to BED of Brachytherapy, when irradiation time is small. Here an attempt is made to correlate these two predominant modes of radiotherapy techniques. PMID:24125964

  11. Potential risk of alpha-glucosidase inhibitor administration in prostate cancer external radiotherapy by exceptional rectal gas production: a case report

    PubMed Central

    2014-01-01

    Introduction Radiotherapy is a standard treatment for prostate cancer, and image-guided radiotherapy is increasingly being used to aid precision of dose delivery to targeted tissues. However, precision during radiotherapy cannot be maintained when unexpected intrafraction organ motion occurs. Case presentation We report our experience of internal organ motion caused by persistent gas production in a patient taking an alpha-glucosidase inhibitor. A 68-year-old Japanese man with prostate cancer visited our institution for treatment with helical tomotherapy. He suffered from diabetes mellitus and took an alpha-glucosidase inhibitor. Routine treatment planning computed tomography showed a large volume of rectal gas; an enema was given to void the rectum. Subsequent treatment planning computed tomography again showed a large volume of gas. After exercise (walking) to remove the intestinal gas, a third scan was performed as a test scan without tight fixation, which showed a sufficiently empty rectum for planning. However, after only a few minutes, treatment planning computed tomography again showed extreme accumulation of gas. Therefore, we postponed treatment planning computed tomography and consulted his doctor to suspend the alpha-glucosidase inhibitor, which was the expected cause of his persistent gas. Four days after the alpha-glucosidase inhibitor regimen was suspended, we took a fourth treatment planning computed tomography and made a treatment plan without gas accumulation. Thereafter, the absence of rectal gas accumulation was confirmed using daily megavolt computed tomography before treatment, and the patient received 37 fractions of intensity-modified radiotherapy at 74Gy without rectal gas complications. In this case study, the alpha-glucosidase inhibitor induced the accumulation of intestinal gas, which may have caused unexpected organ motion, untoward reactions, and insufficient doses to clinical targets. Conclusions We suggest that patients who are taking

  12. EURADOS INTERCOMPARISONS IN EXTERNAL RADIATION DOSIMETRY: SIMILARITIES AND DIFFERENCES AMONG EXERCISES FOR WHOLE-BODY PHOTON, WHOLE-BODY NEUTRON, EXTREMITY, EYE-LENS AND PASSIVE AREA DOSEMETERS.

    PubMed

    Romero, Ana M; Grimbergen, Tom; McWhan, Andrew; Stadtmann, Hannes; Fantuzzi, Elena; Clairand, Isabelle; Neumaier, Stefan; Figel, Markus; Dombrowski, Harald

    2016-09-01

    The European Radiation Dosimetry Group (EURADOS) has been organising dosimetry intercomparisons for many years in response to an identified requirement from individual monitoring services (IMS) for independent performance tests for dosimetry systems. The participation in intercomparisons gives IMS the opportunity to show compliance with their own quality management system, compare results with other participants and develop plans for improving their dosimetry systems. In response to growing demand, EURADOS has increased the number of intercomparisons for external radiation dosimetry. Most of these fit into the programme of self-financing intercomparisons for dosemeters routinely used by IMS. This programme is being coordinated by EURADOS working group 2 (WG2). Up to now, this programme has included four intercomparisons for whole-body dosemeters in photon fields, one for extremity dosemeters in photon and beta fields, and one for whole-body dosemeters in neutron fields. Other EURADOS working groups have organised additional intercomparisons including events in 2014 for eye-lens dosemeters and passive area dosemeters for environmental monitoring. In this paper, the organisation and achievements of these intercomparisons are compared in detail focusing on the similarities and differences in their execution. PMID:26759475

  13. Photon-activation therapy

    SciTech Connect

    Fairchild, R.G.; Bond, V.P.

    1982-01-01

    Photon Activation Therapy (PAT) is a technique in which radiation dose to tumor is enhanced via introduction of stable /sup 127/I in the form of iodinated deoxyuridine (IdUrd). Stimulation of cytotoxic effects from IdUrd is accomplished by activation with external (or implanted) radiation sources. Thus, accumulations of this nucleoside in actively competing cellpools do not preclude therapy in so far as such tissues can be excluded from the radiation field. Calculations show that 5% replacement of thymidine (Tyd) in tumor DNA should enhance the biological effectiveness of a given photon radiotherapy dose by a factor of approx. 3. Proportionally higher gains would result from higher replacements of Tyd and IdUrd. In addition, biological response is enhanced by chemical sensitization with IdUrd. The data indicate that damage from photon activation as well as chemical sensitization does not repair. Thus, at low dose rates, a further increase in therapeutic gain should accrue as normal tissues are allowed to repair and regenerate. A samarium-145 source has been developed for PAT, with activating x-ray energies of from 38 to 45 keV. Favorable clinical results can be expected through the use of IdUrd and protracted irradiations with low energy x-rays. In particular, PAT may provide unique advantages at selected sites such as brain, or head and neck tumors. (ERB)

  14. Verification of external exposure assessment for the upper Techa riverside by luminescence measurements and Monte Carlo photon transport modeling.

    PubMed

    Taranenko, V; Meckbach, R; Degteva, M O; Bougrov, N G; Göksu, Y; Vorobiova, M I; Jacob, P

    2003-04-01

    An area located in the Southern Urals was contaminated in 1949-1956 as a result of radioactive waste releases into the Techa river by the Mayak Production Association. The external dose reconstruction of the Techa river dosimetry system (TRDS-2000) for the exposed population is based on an assessment of dose rates in air (DRA) obtained by modeling transport and deposition of radionuclides along the river for the time before 1952 and by gamma dose rate measurements since 1952. The aim of this paper is to contribute to a verification of the TRDS-2000 external dose assessment. Absorbed doses in bricks from a 130-year-old building in the heavily exposed Metlino settlement were measured by a luminescence technique. By the autumn of 1956 the population of Metlino had been evacuated, and then a water reservoir was created at the village location, which led to a change in the radioactive source geometry. Radiation transport calculations for assumed environmental sources before and since 1957 were performed with the MCNP Monte Carlo code. In combination with TRDS-2000 estimates for annual dose rates in air at the shore of the Techa river for the period 1949-1956 and contemporary dose rate in air measurements, absorbed doses in bricks were calculated. These calculations were performed deterministically with best estimates of the modeling parameters and stochastically by propagating uncertainty distributions through the calculation scheme. Assessed doses in bricks were found to be consistent with measured values within the uncertainty bounds, while their best estimates were approximately 15% lower than the luminescence measurements. PMID:12687379

  15. Topical application of a sandal wood oil and turmeric based cream prevents radiodermatitis in head and neck cancer patients undergoing external beam radiotherapy: a pilot study

    PubMed Central

    Palatty, P L; Azmidah, A; Rao, S; Jayachander, D; Thilakchand, K R; Rai, M P; Haniadka, R; Simon, P; Ravi, R; Jimmy, R; D'souza, P F; Fayad, R

    2014-01-01

    Objective: The study objective was to assess the effectiveness of a turmeric- and sandal wood oil-containing cream [Vicco® turmeric cream (VTC); Vicco Laboratories, Parel, India] on radiodermatitis in patients with head and neck cancer undergoing radiotherapy. Methods: A total of 50 patients with head and neck cancer requiring >60 Gy of curative radiotherapy/chemoradiotherapy were enrolled in the study. The volunteers were randomly divided into two groups of 25 patients. Group 1 was assigned to a topical application of Johnson's® baby oil (Johnson & Johnson Ltd, Baddi, India) and Group 2 for VTC. Prophylactic application of the cream was initiated on Day 1 and continued every day until 2 weeks after the end of treatment. Both agents were symmetrically applied within the irradiated field five times a day, and the acute skin reactions were assessed twice weekly in accordance with the Radiation Therapy Oncology Group scores by an investigator who was unaware of the details. Results: The incidence of radiodermatitis increased with the exposure to radiation and was the highest in both groups at Week 7. However, a significant reduction in grades of dermatitis were seen in cohorts applying VTC at all time points, including 2 weeks post radiotherapy (p < 0.015 to p < 0.001). The occurrence of Grade 3 dermatitis was lower in the cohorts using VTC and was statistically significant (p < 0.01). Additionally, follow-up observations 2 weeks after the completion of radiotherapy also showed a reduced degree of radiodermatitis in cohorts applying VTC, which was significant (p = 0.015). Conclusion: VTC is shown to be effective in preventing radiodermatitis and needs to be validated in larger double-blind trials. Advances in knowledge: For the first time, this study shows that the turmeric- and sandal oil-based cream was effective in preventing radiation-induced dermatitis. PMID:24694358

  16. Timing of High-Dose Rate Brachytherapy With External Beam Radiotherapy in Intermediate and High-Risk Localized Prostate CAncer (THEPCA) Patients and Its Effects on Toxicity and Quality of Life: Protocol of a Randomized Feasibility Trial

    PubMed Central

    Palvai, Sreekanth; Harrison, Michael; Shibu Thomas, Sharon; Hayden, Karen; Green, James; Anderson, Oliver; Romero, Lavinia; Lodge, Richard; Burns, Patricia

    2015-01-01

    Background Prostate cancer is the most common cancer in males in the UK and affects around 105 men for every 100,000. The role of radiotherapy in the management of prostate cancer significantly changed over the last few decades with developments in brachytherapy, external beam radiotherapy (EBRT), intensity-modulated radiotherapy (IMRT), and image-guided radiotherapy (IGRT). One of the challenging factors of radiotherapy treatment of localized prostate cancer is the development of acute and late genitourinary and gastrointestinal toxicities. The recent European guidelines suggest that there is no consensus regarding the timing of high-dose rate (HDR) brachytherapy and EBRT. The schedules vary in different institutions where an HDR boost can be given either before or after EBRT. Few centers deliver HDR in between the fractions of EBRT. Objective Assessment of acute genitourinary and gastrointestinal toxicities at various time points to better understand if the order in which treatment modality is delivered (ie, HDR brachytherapy or EBRT first) has an effect on the toxicity profile. Methods Timing of HDR brachytherapy with EBRT in Prostate CAncer (THEPCA) is a single-center, open, randomized controlled feasibility trial in patients with intermediate and high-risk localized prostate cancer. A group of 50 patients aged 18 years old and over with histological diagnosis of prostate cancer (stages T1b-T3BNOMO), will be randomized to one of two treatment arms (ratio 1:1), following explanation of the study and informed consent. Patients in both arms of the study will be treated with HDR brachytherapy and EBRT, however, the order in which they receive the treatments will vary. In Arm A, patients will receive HDR brachytherapy before EBRT. In Arm B (control arm), patients will receive EBRT before HDR brachytherapy. Study outcomes will look at prospective assessment of genitourinary and gastrointestinal toxicities. The primary endpoint will be grade 3 genitourinary toxicity

  17. Organ-confined prostate carcinoma radiation brachytherapy compared with external either photon- or hadron-beam radiation therapy. Just a short up-to-date.

    PubMed

    Alberti, C

    2011-07-01

    Both low dose rate (LDR) permanent either 1251 or 103Pd seed implant and high dose rate (HDR) 1921r temporary implant are an excellent way to release high dose of ionizing radiations to cancerous lesions while significantly sparing the surrounding healthy tissues. Therefore, the radiation brachytherapy, among the established treatment options of organ-confined prostate carcinoma--interstitial radiofrequency, high intensity focused ultrasound, cryotherapy--has gained large acceptance in the last decades. The LDR permanent interstitial radioactive seed implantation is often used as monotherapy for low risk prostate carcinoma whereas the HDR temporary implant may useful to treat intermediate-to-high risk prostate tumors as a radiation boost to combined external beam radiation therapy (EBRT). On the other hand, with recent refinement of EBRT techniques--either three-dimensional conformal- or intensity-modulated radiotherapy, cyber-knife radiosurgery with even 4D-high resolution image-guided tracking--high doses of X-rays may be precisely delivered to prostate malignant lesions without increasing toxicity for surrounding normal structures. Also hadron therapy is an increasingly successful technique that allows the release of effective energy of protons (H+), neutrons or carbon ions (6(12)C) to the limited extent of the cancerous target site, thus destroying malignant lesion with millimetric precision--just as bloodless surgery--while less damaging the neighbouring healthy tissues. Looking to the near future, even more effective oncotherapy modality appears to be the use of antiprotons because of their highly confined energy deposition at well defined body dept around the annihilation point in contact with protons of the ordinary matter, so targeting only a very limited body volume. PMID:21780545

  18. A randomized, double-blind, placebo-controlled, cross-over study to assess the efficacy of tadalafil (Cialis[reg]) in the treatment of erectile dysfunction following three-dimensional conformal external-beam radiotherapy for prostatic carcinoma

    SciTech Connect

    Incrocci, Luca . E-mail: l.incrocci@erasmusmc.nl; Slagter, Cleo; Slob, A. Koos; Hop, Wim C.J.

    2006-10-01

    Purpose: Erectile dysfunction after three-dimensional conformal external-beam radiotherapy (3DCRT) for prostatic carcinoma is reported in as many as 64% of those patients. The purpose of this study was to determine the efficacy of the oral drug tadalafil (Cialis (registered) ) in patients with erectile dysfunction after radiotherapy for prostatic carcinoma. Methods and Materials: Patients (N = 358) who completed radiotherapy at least 12 months before the study were approached by mail. All patients had been treated by 3DCRT; 60 patients were included and entered a double-blind, placebo-controlled, cross-over study lasting 12 weeks. They received 20 mg of tadalafil or placebo for 6 weeks. Drug or placebo was taken on demand at patient's discretion, with no restrictions regarding the consumption of alcohol or food, at least once a week and no more than once daily. At 6 weeks patients crossed over to the alternative treatment. Data were collected using the Sexual Encounter Profile (SEP) and the International Index of Erectile Function (IIEF) questionnaires. Side effects were also recorded. Results: Mean age at study entry was 69 years. All patients completed the study. For almost all questions of the IIEF questionnaire there was a significant increase in mean scores from baseline with tadalafil, but not with placebo. Sixty-seven percent of the patients reported an improvement of erectile function with tadalafil (placebo: 20%), and 48% reported successful intercourse with tadalafil (placebo: 9%) (p < 0.0001). Side effects were mild or moderate. Conclusions: Tadalafil is an effective treatment for erectile dysfunction after 3DCRT for prostatic carcinoma with successful intercourse reported in almost 50% of the patients, and it is well tolerated.

  19. Volumetric modulated arc planning for lung stereotactic body radiotherapy using conventional and unflattened photon beams: a dosimetric comparison with 3D technique

    PubMed Central

    2011-01-01

    Purpose Frequently, three-dimensional (3D) conformal beams are used in lung cancer stereotactic body radiotherapy (SBRT). Recently, volumetric modulated arc therapy (VMAT) was introduced as a new treatment modality. VMAT techniques shorten delivery time, reducing the possibility of intrafraction target motion. However dose distributions can be quite different from standard 3D therapy. This study quantifies those differences, with focus on VMAT plans using unflattened photon beams. Methods A total of 15 lung cancer patients previously treated with 3D or VMAT SBRT were randomly selected. For each patient, non-coplanar 3D, coplanar and non-coplanar VMAT and flattening filter free VMAT (FFF-VMAT) plans were generated to meet the same objectives with 50 Gy covering 95% of the PTV. Two dynamic arcs were used in each VMAT plan. The couch was set at ± 5° to the 0° straight position for the two non-coplanar arcs. Pinnacle version 9.0 (Philips Radiation Oncology, Fitchburg WI) treatment planning system with VMAT capabilities was used. We analyzed the conformity index (CI), which is the ratio of the total volume receiving at least the prescription dose to the target volume receiving at least the prescription dose; the conformity number (CN) which is the ratio of the target coverage to CI; and the gradient index (GI) which is the ratio of the volume of 50% of the prescription isodose to the volume of the prescription isodose; as well as the V20, V5, and mean lung dose (MLD). Paired non-parametric analysis of variance tests with post-tests were performed to examine the statistical significance of the differences of the dosimetric indices. Results Dosimetric indices CI, CN and MLD all show statistically significant improvement for all studied VMAT techniques compared with 3D plans (p < 0.05). V5 and V20 show statistically significant improvement for the FFF-VMAT plans compared with 3D (p < 0.001). GI is improved for the FFF-VMAT and the non-coplanar VMAT plans (p < 0.01 and p

  20. Skeletal dosimetry for external exposures to photons based on {mu}CT images of spongiosa: Consideration of voxel resolution, cluster size, and medullary bone surfaces

    SciTech Connect

    Kramer, R.; Khoury, H. J.; Vieira, J. W.; Brown, K. A. Robson

    2009-11-15

    Skeletal dosimetry based on {mu}CT images of trabecular bone has recently been introduced to calculate the red bone marrow (RBM) and the bone surface cell (BSC) equivalent doses in human phantoms for external exposure to photons. In order to use the {mu}CT images for skeletal dosimetry, spongiosa voxels in the skeletons were replaced at run time by so-called micromatrices, which have exactly the size of a spongiosa voxel and contain segmented trabecular bone and marrow microvoxels. A cluster (=parallelepiped) of 2x2x2=8 micromatrices was used systematically and periodically throughout the spongiosa volume during the radiation transport calculation. Systematic means that when a particle leaves a spongiosa voxel to enter into a neighboring spongiosa voxel, then the next micromatrix in the cluster will be used. Periodical means that if the particle travels through more than two spongiosa voxels in a row, then the cluster will be repeated. Based on the bone samples available at the time, clusters of up to 3x3x3=27 micromatrices were studied. While for a given trabecular bone volume fraction the whole-body RBM equivalent dose showed converging results for cluster sizes between 8 and 27 micromatrices, this was not the case for the BSC equivalent dose. The BSC equivalent dose seemed to be very sensitive to the number, form, and thickness of the trabeculae. In addition, the cluster size and/or the microvoxel resolution were considered to be possible causes for the differences observed. In order to resolve this problem, this study used a bone sample large enough to extract clusters containing up to 8x8x8=512 micromatrices and which was scanned with two different voxel resolutions. Taking into account a recent proposal, this investigation also calculated the BSC equivalent dose on medullary surfaces of cortical bone in the arm and leg bones. The results showed (1) that different voxel resolutions have no effect on the RBM equivalent dose but do influence the BSC equivalent

  1. Single-photon emission at a rate of 143 MHz from a deterministic quantum-dot microlens triggered by a mode-locked vertical-external-cavity surface-emitting laser

    NASA Astrophysics Data System (ADS)

    Schlehahn, A.; Gaafar, M.; Vaupel, M.; Gschrey, M.; Schnauber, P.; Schulze, J.-H.; Rodt, S.; Strittmatter, A.; Stolz, W.; Rahimi-Iman, A.; Heindel, T.; Koch, M.; Reitzenstein, S.

    2015-07-01

    We report on the realization of a quantum dot (QD) based single-photon source with a record-high single-photon emission rate. The quantum light source consists of an InGaAs QD which is deterministically integrated within a monolithic microlens with a distributed Bragg reflector as back-side mirror, which is triggered using the frequency-doubled emission of a mode-locked vertical-external-cavity surface-emitting laser (ML-VECSEL). The utilized compact and stable laser system allows us to excite the single-QD microlens at a wavelength of 508 nm with a pulse repetition rate close to 500 MHz at a pulse width of 4.2 ps. Probing the photon statistics of the emission from a single QD state at saturation, we demonstrate single-photon emission of the QD-microlens chip with g(2)(0) < 0.03 at a record-high single-photon flux of (143 ± 16) MHz collected by the first lens of the detection system. Our approach is fully compatible with resonant excitation schemes using wavelength tunable ML-VECSELs, which will optimize the quantum optical properties of the single-photon emission in terms of photon indistinguishability.

  2. Single-photon emission at a rate of 143 MHz from a deterministic quantum-dot microlens triggered by a mode-locked vertical-external-cavity surface-emitting laser

    SciTech Connect

    Schlehahn, A.; Gschrey, M.; Schnauber, P.; Schulze, J.-H.; Rodt, S.; Strittmatter, A.; Heindel, T. Reitzenstein, S.; Gaafar, M.; Vaupel, M.; Stolz, W.; Rahimi-Iman, A.; Koch, M.

    2015-07-27

    We report on the realization of a quantum dot (QD) based single-photon source with a record-high single-photon emission rate. The quantum light source consists of an InGaAs QD which is deterministically integrated within a monolithic microlens with a distributed Bragg reflector as back-side mirror, which is triggered using the frequency-doubled emission of a mode-locked vertical-external-cavity surface-emitting laser (ML-VECSEL). The utilized compact and stable laser system allows us to excite the single-QD microlens at a wavelength of 508 nm with a pulse repetition rate close to 500 MHz at a pulse width of 4.2 ps. Probing the photon statistics of the emission from a single QD state at saturation, we demonstrate single-photon emission of the QD-microlens chip with g{sup (2)}(0) < 0.03 at a record-high single-photon flux of (143 ± 16) MHz collected by the first lens of the detection system. Our approach is fully compatible with resonant excitation schemes using wavelength tunable ML-VECSELs, which will optimize the quantum optical properties of the single-photon emission in terms of photon indistinguishability.

  3. The evaluation of neutron and gamma ray dose equivalent distributions in patients and the effectiveness of shield materials for high energy photons radiotherapy facilities.

    PubMed

    Ghassoun, J; Senhou, N

    2012-04-01

    In this study, the MCNP5 code was used to model radiotherapy room of a medical linear accelerator operating at 18 MV and to evaluate the neutron and the secondary gamma ray fluences, the energy spectra and the dose equivalent distributions inside a liquid tissue-equivalent (TE) phantom. The obtained results were compared with measured data published in the literature. Moreover, the shielding effects of various neutron material shields on the radiotherapy room wall were also investigated. Our simulation results showed that paraffin wax containing boron carbide presents enough effectiveness to reduce both neutron and secondary gamma ray doses. PMID:22257567

  4. High-dose-rate brachytherapy and hypofractionated external beam radiotherapy combined with long-term hormonal therapy for high-risk and very high-risk prostate cancer: outcomes after 5-year follow-up

    PubMed Central

    Ishiyama, Hiromichi; Satoh, Takefumi; Kitano, Masashi; Tabata, Ken-ichi; Komori, Shouko; Ikeda, Masaomi; Soda, Itaru; Kurosaka, Shinji; Sekiguchi, Akane; Kimura, Masaki; Kawakami, Shogo; Iwamura, Masatsugu; Hayakawa, Kazushige

    2014-01-01

    The purpose of this study was to report the outcomes of high-dose-rate (HDR) brachytherapy and hypofractionated external beam radiotherapy (EBRT) combined with long-term androgen deprivation therapy (ADT) for National Comprehensive Cancer Network (NCCN) criteria-defined high-risk (HR) and very high-risk (VHR) prostate cancer. Data from 178 HR (n = 96, 54%) and VHR (n = 82, 46%) prostate cancer patients who underwent 192Ir-HDR brachytherapy and hypofractionated EBRT with long-term ADT between 2003 and 2008 were retrospectively analyzed. The mean dose to 90% of the planning target volume was 6.3 Gy/fraction of HDR brachytherapy. After five fractions of HDR treatment, EBRT with 10 fractions of 3 Gy was administered. All patients initially underwent ≥6 months of neoadjuvant ADT, and adjuvant ADT was continued for 36 months after EBRT. The median follow-up was 61 months (range, 25–94 months) from the start of radiotherapy. The 5-year biochemical non-evidence of disease, freedom from clinical failure and overall survival rates were 90.6% (HR, 97.8%; VHR, 81.9%), 95.2% (HR, 97.7%; VHR, 92.1%), and 96.9% (HR, 100%; VHR, 93.3%), respectively. The highest Radiation Therapy Oncology Group-defined late genitourinary toxicities were Grade 2 in 7.3% of patients and Grade 3 in 9.6%. The highest late gastrointestinal toxicities were Grade 2 in 2.8% of patients and Grade 3 in 0%. Although the 5-year outcome of this tri-modality approach seems favorable, further follow-up is necessary to validate clinical and survival advantages of this intensive approach compared with the standard EBRT approach. PMID:24222312

  5. Dose reconstruction technique using non-rigid registration to evaluate spatial correspondence between high-dose region and late radiation toxicity: a case of tracheobronchial stenosis after external beam radiotherapy combined with endotracheal brachytherapy for tracheal cancer

    PubMed Central

    Murakami, Naoya; Inaba, Koji; Wakita, Akihisa; Nakamura, Satoshi; Okamoto, Hiroyuki; Sato, Jun; Umezawa, Rei; Takahashi, Kana; Igaki, Hiroshi; Ito, Yoshinori; Shigematsu, Naoyuki; Itami, Jun

    2016-01-01

    Purpose Small organ subvolume irradiated by a high-dose has been emphasized to be associated with late complication after radiotherapy. Here, we demonstrate a potential use of surface-based, non-rigid registration to investigate how high-dose volume topographically correlates with the location of late radiation morbidity in a case of tracheobronchial radiation stenosis. Material and methods An algorithm of point set registration was implemented to handle non-rigid registration between contour points on the organ surfaces. The framework estimated the global correspondence between the dose distribution and the varying anatomical structure. We applied it to an 80-year-old man who developed tracheobronchial stenosis 2 years after high-dose-rate endobronchial brachytherapy (HDR-EBT) (24 Gy in 6 Gy fractions) and external beam radiotherapy (EBRT) (40 Gy in 2 Gy fractions) for early-stage tracheal cancer. Results and conclusions Based on the transformation function computed by the non-rigid registration, irradiated dose distribution was reconstructed on the surface of post-treatment tracheobronchial stenosis. For expressing the equivalent dose in a fractional dose of 2 Gy in HDR-EBT, α/β of linear quadratic model was assumed as 3 Gy for the tracheal bronchus. The tracheobronchial surface irradiated by more than 100 Gyαβ3 tended to develop severe stenosis, which attributed to a more than 50% decrease in the luminal area. The proposed dose reconstruction technique can be a powerful tool to predict late radiation toxicity with spatial consideration. PMID:27257421

  6. Bone Fractures Following External Beam Radiotherapy and Limb-Preservation Surgery for Lower Extremity Soft Tissue Sarcoma: Relationship to Irradiated Bone Length, Volume, Tumor Location and Dose

    SciTech Connect

    Dickie, Colleen I.; Parent, Amy L.; Griffin, Anthony M.; Fung, Sharon; Chung, Peter W.M.; Catton, Charles N.; Ferguson, Peter C.; Wunder, Jay S.; Bell, Robert S.; Sharpe, Michael B.; O'Sullivan, Brian

    2009-11-15

    Purpose: To examine the relationship between tumor location, bone dose, and irradiated bone length on the development of radiation-induced fractures for lower extremity soft tissue sarcoma (LE-STS) patients treated with limb-sparing surgery and radiotherapy (RT). Methods and Materials: Of 691 LE-STS patients treated from 1989 to 2005, 31 patients developed radiation-induced fractures. Analysis was limited to 21 fracture patients (24 fractures) who were matched based on tumor size and location, age, beam arrangement, and mean total cumulative RT dose to a random sample of 53 nonfracture patients and compared for fracture risk factors. Mean dose to bone, RT field size (FS), maximum dose to a 2-cc volume of bone, and volume of bone irradiated to >=40 Gy (V40) were compared. Fracture site dose was determined by comparing radiographic images and surgical reports to fracture location on the dose distribution. Results: For fracture patients, mean dose to bone was 45 +- 8 Gy (mean dose at fracture site 59 +- 7 Gy), mean FS was 37 +- 8 cm, maximum dose was 64 +- 7 Gy, and V40 was 76 +- 17%, compared with 37 +- 11 Gy, 32 +- 9 cm, 59 +- 8 Gy, and 64 +- 22% for nonfracture patients. Differences in mean, maximum dose, and V40 were statistically significant (p = 0.01, p = 0.02, p = 0.01). Leg fractures were more common above the knee joint. Conclusions: The risk of radiation-induced fracture appears to be reduced if V40 <64%. Fracture incidence was lower when the mean dose to bone was <37 Gy or maximum dose anywhere along the length of bone was <59 Gy. There was a trend toward lower mean FS for nonfracture patients.

  7. External Beam Radiotherapy Plus 24-Hour Continuous Infusion of Gemcitabine in Unresectable Pancreatic Carcinoma: Long-Term Results of a Phase II Study

    SciTech Connect

    Mattiucci, Gian C.; Morganti, Alessio G.; Valentini, Vincenzo; Ippolito, Edy; Alfieri, Sergio; Antinori, Armando; Crucitti, Antonio; D'Agostino, Giuseppe R.; Di Lullo, Liberato; Luzi, Stefano; Mantini, Giovanna; Smaniotto, Daniela; Doglietto, Gian B.; Cellini, Numa

    2010-03-01

    Purpose: To evaluate the efficacy of gemcitabine-based chemoradiation (CT-RT) in treating patients (pts) affected by locally advanced pancreatic cancers (LAPC). Methods and Materials: Weekly gemcitabine (100 mg/m{sup 2}) was given as a 24-hour infusion during the course of three-dimensional radiotherapy (50.4 Gy to the tumor, 39.6 Gy to the nodes). After CT-RT, pts received five cycles of sequential chemotherapy with gemcitabine (1000 mg/m{sup 2}; 1, 8, q21). Response rate was assessed according to World Health Organization criteria 6 weeks after the end of CT-RT. Local control (LC), time to progression (TTP), metastases-free survival (MFS), and overall survival (OS) were analyzed by the Kaplan Meier method. Results: Forty pts (male/female 22/18; median age 62 years, range, 36-76) were treated from 2000 to 2005. The majority had T4 tumour (n = 34, 85%), six pts (15%) had T3 tumour. Sixteen pts (40%) were node positive at diagnosis. Grade 3-4 acute toxicity was observed in 21 pts (52.5%). Thirty pts (75%) completed the treatment schedule. A clinical response was achieved in 12 pts (30%). With a median follow-up of 76 months (range, 32-98), 2-year LC was 39.6% (median, 12 months), 2-year TTP was 18.4% (median, 10 months), and 2-year MFS was 29.7% (median, 10 months). Two-year OS (25%; median, 15.5 months) compared with our previous study on 5-fluorouracil-based CT-RT (2.8%) was significantly improved (p <0.001). Conclusions: Gemcitabine CT-RT seems correlated with improved outcomes. Healthier patients who are likely to complete the treatment schedule may benefit most from this therapy.

  8. Determinants of Toxicity, Patterns of Failure, and Outcome Among Adult Patients With Soft Tissue Sarcomas of the Extremity and Superficial Trunk Treated With Greater Than Conventional Doses of Perioperative High-Dose-Rate Brachytherapy and External Beam Radiotherapy

    SciTech Connect

    San Miguel, Inigo; San Julian, Mikel; Cambeiro, Mauricio; Sanmamed, Miguel Fernandez; Vazquez-Garcia, Blanca; Pagola, Maria; Gaztanaga, Miren; Martin-Algarra, Salvador; Martinez-Monge, Rafael

    2011-11-15

    Purpose: The present study was undertaken to determine factors predictive of toxicity, patterns of failure, and survival in 60 adult patients with soft tissue sarcomas of the extremity and superficial trunk treated with combined perioperative high-dose-rate brachytherapy and external beam radiotherapy. Methods and Materials: The patients were treated with surgical resection and perioperative high-dose-rate brachytherapy (16 or 24 Gy) for negative and close/microscopically positive resection margins, respectively. External beam radiotherapy (45 Gy) was added postoperatively to reach a 2-Gy equivalent dose of 62.9 and 72.3 Gy, respectively. Adjuvant chemotherapy with ifosfamide and doxorubicin was given to patients with advanced high-grade tumors. Results: Grade 3 toxic events were observed in 18 patients (30%) and Grade 4 events in 6 patients (10%). No Grade 5 events were observed. A location in the lower limb was significant for Grade 3 or greater toxic events on multivariate analysis (p = .013), and the tissue volume encompassed by the 150% isodose line showed a trend toward statistical significance (p = .086). The local control, locoregional control, and distant control rate at 9 years was 77.4%, 69.5%, and 63.8%, respectively. On multivariate analysis, microscopically involved margins correlated with local control (p = .036) and locoregional control (p = .007) and tumor size correlated with distant metastases (p = .004). The 9-year disease-free survival and overall survival rate was 47.0% and 61.5%, respectively. Multivariate analysis showed poorer disease-free survival rates for patients with tumors >6 cm (p = .005) and microscopically involved margins (p = .043), and overall survival rates decreased with increasing tumor size (p = .011). Conclusions: Grade 3 or greater wound complications can probably be decreased using meticulous treatment planning to decrease the tissue volume encompassed by the 150% isodose line, especially in lower limb locations

  9. [Stereotactic radiotherapy in brain metastases].

    PubMed

    Dhermain, F; Reyns, N; Colin, P; Métellus, P; Mornex, F; Noël, G

    2015-02-01

    Stereotactic radiotherapy of brain metastases is increasingly proposed after polydisciplinary debates among experts. Its definition and modalities of prescription, indications and clinical interest regarding the balance between efficacy versus toxicity need to be discussed. Stereotactic radiotherapy is a 'high precision' irradiation technique (within 1mm), using different machines (with invasive contention or frameless, photons X or gamma) delivering high doses (4 to 25Gy) in a limited number of fractions (usually 1 to 5, ten maximum) with a high dose gradient. Dose prescription will depend on materials, dose constraints to organs at risk varying with fractionation. Stereotactic radiotherapy may be proposed: (1) in combination with whole brain radiotherapy with the goal of increasing (modestly) overall survival of patients with a good performance status, 1 to 3 brain metastases and a controlled extracranial disease; (2) for recurrence of 1-3 brain metastases after whole brain radiotherapy; (3) after complete resection of a large and/or symptomatic brain metastases; (4) after diagnosis of 3-5 asymptomatic new or progressing brain metastases during systemic therapy, with the aim of delaying whole brain radiotherapy (avoiding its potential neurotoxicity) and maintaining a high focal control rate. Only a strict follow-up with clinical and MRI every 3 months will permit to deliver iterative stereotactic radiotherapies without jeopardizing survival. Simultaneous delivering of stereotactic radiotherapy with targeted medicines should be carefully discussed. PMID:25640215

  10. Consideration of the ICRP 2006 revised tissue weighting factors on age-dependent values of the effective dose for external photons.

    PubMed

    Lee, Choonsik; Lee, Choonik; Han, Eun Young; Bolch, Wesley E

    2007-01-01

    The effective dose recommended by the International Commission on Radiological Protection (ICRP) is the sum of organ equivalent doses weighted by corresponding tissue weighting factors, w(T). ICRP is in the process of revising its 1990 recommendations on the effective dose where new values of organs and tissue weighting factors have been proposed and published in draft form for consultation by the radiological protection community. In its 5 June 2006 draft recommendations, new organs and tissues have been introduced in the effective dose which do not exist within the 1987 Oak Ridge National Laboratory (ORNL) phantom series (e.g., salivary glands). Recently, the investigators at University of Florida have updated the series of ORNL phantoms by implementing new organ models and adopting organ-specific elemental composition and densities. In this study, the effective dose changes caused by the transition from the current recommendation of ICRP Publication 60 to the 2006 draft recommendations were investigated for external photon irradiation across the range of ICRP reference ages (newborn, 1-year, 5-year, 10-year, 15-year and adult) and for six idealized irradiation geometries: anterior-posterior (AP), posterior-anterior (PA), left-lateral (LLAT), right-lateral (RLAT), rotational (ROT) and isotropic (ISO). Organ-absorbed doses were calculated by implementing the revised ORNL phantoms in the Monte Carlo radiation transport code, MCNPX2.5, after which effective doses were calculated under the 1990 and draft 2006 evaluation schemes of the ICRP. Effective doses calculated under the 2006 draft scheme were slightly higher than estimated under ICRP Publication 60 methods for all irradiation geometries exclusive of the AP geometry where an opposite trend was observed. The effective doses of the adult phantom were more greatly affected by the change in tissue weighting factors than that seen within the paediatric members of the phantom series. Additionally, dose conversion

  11. Fiber-coupled organic plastic scintillator for on-line dose rate monitoring in 6 MV X-ray beam for external radiotherapy

    NASA Astrophysics Data System (ADS)

    Lindvold, Lars R.; Beierholm, A. R.; Andersen, C. E.

    2010-02-01

    Fiber-coupled organic plastic scintillators enable on-line dose rate monitoring in conjunction with pulsed radiation sources like linear medical accelerators (linacs). The accelerator, however, generates a significant amount of stray ionizing radiation. This radiation excites the long optical fiber (15-20 m), connecting the scintillator, typically with a diameter of 1 mm and 5 mm in length, with the optical detector circuit, causing parasitic luminescence in the optical fiber. In this paper we propose a method for circumventing this problem. The method is based on the use of an organic scintillator, 2-Naphthoic acid, doped in an optical polymer. The organic scintillator possesses a long luminescent lifetime (room temperature phosphorescence). The scintillator is molded onto the distal end of a polymer optical fiber. The luminescent signal from the scintillator is detected by a PMT in photon-counting mode. The long lifetime of the scintillator signal facilitates a temporal gating of the dose rate signal with respect to the parasitic luminescence from the optical fiber. We will present data obtained using a solid water phantom irradiated with 6 MV Xrays from a medical linac at the Copenhagen University Hospital. Also issues pertaining to the selection of proper matrix as well as phosphorescent dye will be presented in this paper.

  12. Anatomy-based inverse optimization in high-dose-rate brachytherapy combined with hypofractionated external beam radiotherapy for localized prostate cancer: Comparison of incidence of acute genitourinary toxicity between anatomy-based inverse optimization and geometric optimization

    SciTech Connect

    Akimoto, Tetsuo . E-mail: takimoto@showa.gunma-u.ac.jp; Katoh, Hiroyuki; Kitamoto, Yoshizumi; Shirai, Katsuyuki; Shioya, Mariko; Nakano, Takashi

    2006-04-01

    Purpose: To evaluate the advantages of anatomy-based inverse optimization (IO) in planning high-dose-rate (HDR) brachytherapy. Methods and Materials: A total of 114 patients who received HDR brachytherapy (9 Gy in two fractions) combined with hypofractionated external beam radiotherapy (EBRT) were analyzed. The dose distributions of HDR brachytherapy were optimized using geometric optimization (GO) in 70 patients and by anatomy-based IO in the remaining 44 patients. The correlation between the dose-volume histogram parameters, including the urethral dose and the incidence of acute genitourinary (GU) toxicity, was evaluated. Results: The averaged values of the percentage of volume receiving 80-150% of the prescribed minimal peripheral dose (V{sub 8}-V{sub 15}) of the urethra generated by anatomy-based IO were significantly lower than the corresponding values generated by GO. Similarly, the averaged values of the minimal dose received by 5-50% of the target volume (D{sub 5}-D{sub 5}) obtained using anatomy-based IO were significantly lower than those obtained using GO. Regarding acute toxicity, Grade 2 or worse acute GU toxicity developed in 23% of all patients, but was significantly lower in patients for whom anatomy-based IO (16%) was used than in those for whom GO was used (37%), consistent with the reduced urethral dose (p <0.01). Conclusion: The results of this study suggest that anatomy-based IO is superior to GO for dose optimization in HDR brachytherapy for prostate cancer.

  13. Squamous cell carcinoma of external auditory canal lacking epidermal growth factor receptor protein overexpression, in an elderly Omani with oculocutaneous albinism treated with palliative radiotherapy.

    PubMed

    Furrukh, Muhammad; Mufti, Taha; Hamid, Rana Shoaib; Qureshi, Asim

    2014-01-01

    We report a case of squamous cell carcinoma of external auditory canal in an Omani man with oculocutaneous albinism. The disease mimicked inflammatory process revealing positive cultures for various microorganisms during the course of his illness. He was eventually biopsied to rule out atypical infective process or presence of malignancy. He was staged as T4N0M0 and treated with radical doses of palliative radiation therapy which was very well tolerated and resulted in a complete resolution of disease clinically and a major soft tissue response on radiological imaging. Another unique finding was the absence of epidermal growth factor receptor (EGFR) protein overexpression in the tumour specimen. More than 90% of mucosal squamous cell carcinoma (SCC) involving the head and neck region overexpress the EGFR protein in normal skin patients. SCC is the predominant cutaneous malignancy in albinos, and the presence of EGFR protein overexpression in cutaneous SCC is believed to be 56-58% in normal skin patients. The scientific literature is scarce on reporting incidence of EGFR overexpression in either cutaneous or mucosal SCC in albinos, and it remains to be defined whether being albino is the cause for its absence. PMID:24907210

  14. Squamous cell carcinoma of external auditory canal lacking epidermal growth factor receptor protein overexpression, in an elderly Omani with oculocutaneous albinism treated with palliative radiotherapy

    PubMed Central

    Furrukh, Muhammad; Mufti, Taha; Hamid, Rana Shoaib; Qureshi, Asim

    2014-01-01

    We report a case of squamous cell carcinoma of external auditory canal in an Omani man with oculocutaneous albinism. The disease mimicked inflammatory process revealing positive cultures for various microorganisms during the course of his illness. He was eventually biopsied to rule out atypical infective process or presence of malignancy. He was staged as T4N0M0 and treated with radical doses of palliative radiation therapy which was very well tolerated and resulted in a complete resolution of disease clinically and a major soft tissue response on radiological imaging. Another unique finding was the absence of epidermal growth factor receptor (EGFR) protein overexpression in the tumour specimen. More than 90% of mucosal squamous cell carcinoma (SCC) involving the head and neck region overexpress the EGFR protein in normal skin patients. SCC is the predominant cutaneous malignancy in albinos, and the presence of EGFR protein overexpression in cutaneous SCC is believed to be 56–58% in normal skin patients. The scientific literature is scarce on reporting incidence of EGFR overexpression in either cutaneous or mucosal SCC in albinos, and it remains to be defined whether being albino is the cause for its absence. PMID:24907210

  15. Cerenkov emission induced by external beam radiation stimulates molecular fluorescence

    SciTech Connect

    Axelsson, Johan; Davis, Scott C.; Gladstone, David J.; Pogue, Brian W.

    2011-07-15

    Purpose: Cerenkov emission is induced when a charged particle moves faster than the speed of light in a given medium. Both x-ray photons and electrons produce optical Cerenkov photons in everyday radiation therapy of tissue; yet, this phenomenon has never been fully documented. This study quantifies the emissions and also demonstrates that the Cerenkov emission can excite a fluorophore, protoporphyrin IX (PpIX), embedded in biological phantoms. Methods: In this study, Cerenkov emission induced by radiation from a clinical linear accelerator is investigated. Biological mimicking phantoms were irradiated with x-ray photons, with energies of 6 or 18 MV, or electrons at energies 6, 9, 12, 15, or 18 MeV. The Cerenkov emission and the induced molecular fluorescence were detected by a camera or a spectrometer equipped with a fiber optic cable. Results: It is shown that both x-ray photons and electrons, at MeV energies, produce optical Cerenkov photons in tissue mimicking media. Furthermore, we demonstrate that the Cerenkov emission can excite a fluorophore, protoporphyrin IX (PpIX), embedded in biological phantoms. Conclusions: The results here indicate that molecular fluorescence monitoring during external beam radiotherapy is possible.

  16. Effect of external magnetic field on the Kβ/Kα X-ray intensity ratios of TixNi1-x alloys excited by 59.54 and 22.69keV photons.

    PubMed

    Perişanoğlu, Ufuk; Alım, Bünyamin; Uğurlu, Mine; Demir, Lütfü

    2016-09-01

    The effects of external magnetic field and exciting photon energies on the Kβ/Kα X-ray intensity ratios of various alloy compositions of Ti-Ni transition metal alloys have been investigated in this work using X-ray fluorescence spectroscopy. The spectrum of characteristic K-X-ray photons from pure Ti, pure Ni and TixNi1-x (x=0.30; 0.40; 0.50; 0.60; 0.70) alloys were detected with a high resolution Si (Li) solid-state detector. Firstly, Kβ/Kα X-ray intensity ratios of pure Ti, pure Ni and TixNi1-x alloys were measured following excitation by 59.54keV γ-rays from a 200mCi (241)Am radioactive point source without any magnetic field and under 0.5 and 1T external magnetic fields, separately. Later, the same measurements were repeated under the same experimental conditions for 22.69keV X-rays from a 370 MBq(1)(0)(9)Cd radioactive point source. The results obtained for Kβ/Kα X-ray intensity ratios of pure Ti, pure Ni, Ti and Ni in various Ti-Ni alloys were evaluated in terms of both external magnetic field effect and exciting photon energy effect. When the results obtained for both exciting photon energies are evaluated in terms of changing of Kβ/Kα X-ray intensity ratios depending on the alloy composition, the tendency of these changes are observed to be similar. Also, Kβ/Kα X-ray intensity ratios for all samples examined have changed with increasing external magnetic field. Therefore, the results obtained have shown that Kβ/Kα X-ray intensity ratios of Ti and Ni in TixNi1-x alloys are connected with the external magnetic field. The present study makes it possible to perform reliable interpretation of experimental Kβ/Kα X-ray intensity ratios for Ti, Ni and TixNi1-x alloys and can also provide quantitative information about the changes of the Kβ/Kα X-ray intensity ratios of these metals with alloy composition. PMID:27395003

  17. SU-E-T-55: Biological Equivalent Dose (BED) Comparison Between Permanent Interstitial Brachytherapy and Conventional External Beam Radiotherapy for Prostate Cancer

    SciTech Connect

    Liu, X; Rahimian, J; Cosmatos, H; Goy, B; Heywood, C; Qian, Y

    2014-06-01

    Purpose: The goal of this research is to calculate and compare the Biological Equivalent Dose (BED) between permanent prostate Iodine-125 implant brachytherapy as monotherapy with the BED of conventional external beam radiation therapy (EBRT). Methods: A retrospective study of 605 patients treated with Iodine-125 seed implant was performed in which physician A treated 274 patients and physician B treated 331 patients. All the Brachytherapy treatment plans were created using VariSeed 8 planning system. The Iodine-125 seed source activities and loading patterns varied slightly between the two physicians. The prescription dose is 145 Gy to PTV for each patient. The BED and Tumor Control Probability (TCP) were calculated based on the TG 137 formulas. The BED for conventional EBRT of the prostate given in our institution in 2Gy per fraction for 38 fractions was calculated and compared. Results: Physician A treated 274 patients with an average BED of 123.92±0.87 Gy and an average TCP of 99.20%; Physician B treated 331 patients with an average BED of 124.87±1.12 Gy and an average TCP of 99.30%. There are no statistically significant differences (T-Test) between the BED and TCP values calculated for these two group patients.The BED of the patients undergoing conventional EBRT is calculated to be 126.92Gy. The BED of the patients treated with permanent implant brachytherapy and EBRT are comparable. Our BED and TCP values are higher than the reported values by TG 137 due to higher Iodine-125 seed activity used in our institution. Conclusion: We calculated the BED,a surrogate of the biological response to a permanent prostate brachytherapy using TG 137 formulas and recommendation. The TCP of better than 99% is calculated for these patients. A clinical outcome study of these patients correlating the BED and TCP values with PSA and Gleason Levels as well as patient survival is warranted.

  18. Combination of External Beam Radiotherapy (EBRT) With Intratumoral Injection of Dendritic Cells as Neo-Adjuvant Treatment of High-Risk Soft Tissue Sarcoma Patients

    SciTech Connect

    Finkelstein, Steven E.; Iclozan, Cristina; Bui, Marilyn M.; Cotter, Matthew J.; Ramakrishnan, Rupal; Ahmed, Jamil; Noyes, David R.; Cheong, David; Gonzalez, Ricardo J.; Heysek, Randy V.; Berman, Claudia; Lenox, Brianna C.; Janssen, William; Zager, Jonathan S.; Sondak, Vernon K.; Letson, G. Douglas; Antonia, Scott J.; Gabrilovich, Dmitry I.

    2012-02-01

    Purpose: The goal of this study was to determine the effect of combination of intratumoral administration of dendritic cells (DC) and fractionated external beam radiation (EBRT) on tumor-specific immune responses in patients with soft-tissue sarcoma (STS). Methods and Material: Seventeen patients with large (>5 cm) high-grade STS were enrolled in the study. They were treated in the neoadjuvant setting with 5,040 cGy of EBRT, split into 28 fractions and delivered 5 days per week, combined with intratumoral injection of 10{sup 7} DCs followed by complete resection. DCs were injected on the second, third, and fourth Friday of the treatment cycle. Clinical evaluation and immunological assessments were performed. Results: The treatment was well tolerated. No patient had tumor-specific immune responses before combined EBRT/DC therapy; 9 patients (52.9%) developed tumor-specific immune responses, which lasted from 11 to 42 weeks. Twelve of 17 patients (70.6%) were progression free after 1 year. Treatment caused a dramatic accumulation of T cells in the tumor. The presence of CD4{sup +} T cells in the tumor positively correlated with tumor-specific immune responses that developed following combined therapy. Accumulation of myeloid-derived suppressor cells but not regulatory T cells negatively correlated with the development of tumor-specific immune responses. Experiments with {sup 111}In labeled DCs demonstrated that these antigen presenting cells need at least 48 h to start migrating from tumor site. Conclusions: Combination of intratumoral DC administration with EBRT was safe and resulted in induction of antitumor immune responses. This suggests that this therapy is promising and needs further testing in clinical trials design to assess clinical efficacy.

  19. Intraoperative Radiotherapy in Childhood Malignant Astrocytoma

    PubMed Central

    Rana, Sohail R.; Haddy, Theresa B.; Ashayeri, Ebrahim; Goldson, Alfred L.

    1984-01-01

    A 12-year-old black male patient with glioblastoma multiforme was treated with intraoperative radiotherapy followed by conventional external beam radiation and chemotherapy. The authors' clinical experience with these therapeutic measures is discussed. PMID:6330375

  20. A Dosimetric Evaluation of Conventional Helmet Field Irradiation Versus Two-Field Intensity-Modulated Radiotherapy Technique

    SciTech Connect

    Yu, James B.; Shiao, Stephen L.; Knisely, Jonathan . E-mail: jonathan.knisely@yale.edu

    2007-06-01

    Purpose: To compare dosimetric differences between conventional two-beam helmet field irradiation (external beam radiotherapy, EBRT) of the brain and a two-field intensity-modulated radiotherapy (IMRT) technique. Methods and Materials: Ten patients who received helmet field irradiation at our institution were selected for study. External beam radiotherapy portals were planned per usual practice. Intensity-modulated radiotherapy fields were created using the identical field angles as the EBRT portals. Each brain was fully contoured along with the spinal cord to the bottom of the C2 vertebral body. This volume was then expanded symmetrically by 0.5 cm to construct the planning target volume. An IMRT plan was constructed using uniform optimization constraints. For both techniques, the nominal prescribed dose was 3,000 cGy in 10 fractions of 300 cGy using 6-MV photons. Comparative dose-volume histograms were generated for each patient and analyzed. Results: Intensity-modulated radiotherapy improved dose uniformity over EBRT for whole brain radiotherapy. The mean percentage of brain receiving >105% of dose was reduced from 29.3% with EBRT to 0.03% with IMRT. The mean maximum dose was reduced from 3,378 cGy (113%) for EBRT to 3,162 cGy (105%) with IMRT. The mean percent volume receiving at least 98% of the prescribed dose was 99.5% for the conventional technique and 100% for IMRT. Conclusions: Intensity-modulated radiotherapy reduces dose inhomogeneity, particularly for the midline frontal lobe structures where hot spots occur with conventional two-field EBRT. More study needs to be done addressing the clinical implications of optimizing dose uniformity and its effect on long-term cognitive function in selected long-lived patients.

  1. Lowering Whole-Body Radiation Doses in Pediatric Intensity-Modulated Radiotherapy Through the Use of Unflattened Photon Beams;Flattening filter; Pediatric; Intensity-modulated radiotherapy; Second cancers; Radiation-induced malignancies

    SciTech Connect

    Cashmore, Jason; Ramtohul, Mark; Ford, Dan

    2011-07-15

    Purpose: Intensity modulated radiotherapy (IMRT) has been linked with an increased risk of secondary cancer induction due to the extra leakage radiation associated with delivery of these techniques. Removal of the flattening filter offers a simple way of reducing head leakage, and it may be possible to generate equivalent IMRT plans and to deliver these on a standard linear accelerator operating in unflattened mode. Methods and Materials: An Elekta Precise linear accelerator has been commissioned to operate in both conventional and unflattened modes (energy matched at 6 MV) and a direct comparison made between the treatment planning and delivery of pediatric intracranial treatments using both approaches. These plans have been evaluated and delivered to an anthropomorphic phantom. Results: Plans generated in unflattened mode are clinically identical to those for conventional IMRT but can be delivered with greatly reduced leakage radiation. Measurements in an anthropomorphic phantom at clinically relevant positions including the thyroid, lung, ovaries, and testes show an average reduction in peripheral doses of 23.7%, 29.9%, 64.9%, and 70.0%, respectively, for identical plan delivery compared to conventional IMRT. Conclusions: IMRT delivery in unflattened mode removes an unwanted and unnecessary source of scatter from the treatment head and lowers leakage doses by up to 70%, thereby reducing the risk of radiation-induced second cancers. Removal of the flattening filter is recommended for IMRT treatments.

  2. The Degree of Lipiodol Accumulation Can Be an Indicator of Successful Treatment for Unresectable Hepatocellular Carcinoma (HCC) Patients - in the Case of Transcatheter Arterial Chemoembolization (TACE) and External Beam Radiotherapy (EBRT)

    PubMed Central

    Yang, Ping; Zeng, Zhao-Chong; Wang, Bin-Liang; Zhang, Jian-Ying; Fan, Jia; Zhou, Jian; Hu, Yong

    2016-01-01

    Purpose: Transcatheter arterial chemoembolization (TACE) in combination with external beam radiotherapy (EBRT) results in improved survival due to better local control in patients with unresectable hepatocellular carcinoma (HCC). The purpose of this study was to investigate lipiodol accumulation, as it reflects tumor burden and is a potential prognostic factor, in HCC patients treated with TACE/EBRT. Methods and Materials: We retrospectively studied 147 patients with unresectable HCC treated with TACE and EBRT. Clinical features, adverse reactions, and prognostic factors were analyzed. All patients were treated with TACE 1-6 times in combination with EBRT (44-66 Gy) in dose of 2 Gy/fraction given once a day five times a week. Tumor status and laboratory findings were followed. The degree of lipiodol accumulation was assessed by computed tomography before EBRT, and was categorized as either complete/intense or low/moderate. Results: The response rate of tumor size after EBRT was 68.2%, median survival was 23.1 months, and overall survival rates were 86.6%, 49.2%, and 28.2% at 1, 2, and 3 years, respectively. Univariate analysis showed that lower hemoglobin levels, higher alkaline phosphatase levels, Child-Pugh B, negative alpha-fetoprotein (AFP) response after EBRT, poor treatment response after EBRT, tumor diameter >10 cm, and poor lipiodol accumulation were unfavorable prognostic factors. On multivariate analysis, higher hemoglobin levels, Child-Pugh A, decreased AFP levels after treatment, Helical Tomotherapy (HT) and intense lipiodol accumulation after TACE were significant favorable predictors. Conclusions: The degree of lipiodol accumulation before EBRT is a prognostic factor in patients with unresectable HCC. Increased AFP levels after EBRT are always associated with poor survival. HT is recommended as a potentially better EBRT modality than three-dimensional conformal radiation therapy (3D-CRT). PMID:27471557

  3. Three-dimensional conformal external beam radiotherapy compared with permanent prostate implantation in low-risk prostate cancer based on endorectal magnetic resonance spectroscopy imaging and prostate-specific antigen level

    SciTech Connect

    Pickett, Barby . E-mail: pickett@radonc17.ucsf.edu; Kurhanewicz, John; Pouliot, Jean; Weinberg, Vivian; Shinohara, Katsuto; Coakley, Fergus; Roach, Mack

    2006-05-01

    Purpose: To evaluate the metabolic response by comparing the time to resolution of spectroscopic abnormalities (TRSA) and the time to prostate-specific antigen level in low-risk prostate cancer patients after treatment with three-dimensional conformal external beam radiotherapy (3D-CRT) compared with permanent prostate implantation (PPI). Recent studies have suggested that the treatment of low-risk prostate cancer yields similar results for patients treated with 3D-CRT or PPI. Methods and Materials: A total of 50 patients, 25 in each group, who had been treated with 3D-CRT or PPI, had undergone endorectal magnetic resonance spectroscopy imaging before and/or at varying times after therapy. The 3D-CRT patients had received radiation doses of {>=}72 Gy compared with 144 Gy for the PPI patients. The spectra from all usable voxels were examined for detectable levels of metabolic signal, and the percentages of atrophic and cancerous voxels were tabulated. Results: The median time to resolution of the spectroscopic abnormalities was 32.2 and 24.8 months and the time to the nadir prostate-specific antigen level was 52.4 and 38.0 months for the 3D-CRT and PPI patients, respectively. Of the 3D-CRT patients, 92% achieved negative endorectal magnetic resonance spectroscopy imaging findings, with 40% having complete metabolic atrophy. All 25 PPI patients had negative endorectal magnetic resonance spectroscopy imaging findings, with 60% achieving complete metabolic atrophy. Conclusion: The results of this study suggest that metabolic and biochemical responses of the prostate are more pronounced after PPI. Our results have not proved PPI is more effective at curing prostate cancer, but they have demonstrated that it may be more effective at destroying prostate metabolism.

  4. Multi-energy imagers for a radiotherapy treatment environment

    NASA Astrophysics Data System (ADS)

    Antonuk, Larry E.; Liu, Langechuan; Liang, Albert K.; El-Mohri, Youcef; Zhao, Qihua; Koniczek, Martin; Jiang, Hao

    2015-03-01

    Over the last ~15 years, the central goal in external beam radiotherapy of maximizing dose to the tumor while minimizing dose to surrounding normal tissues has been greatly facilitated by the development and clinical implementation of many innovations. These include megavoltage active matrix flat-panel imagers (MV AMFPIs) designed to image the treatment beam, and separate kilovoltage (kV) AMFPIs and x-ray sources designed to provide high-contrast projection and cone-beam CT images in the treatment room. While these systems provide clinically valuable information, a variety of advantages would accrue through introduction of the capability to produce clinically useful, high quality imaging information at multiple energies (e.g., kV and MV) from a single detector along the treatment beam direction. One possible approach for achieving this goal involves substitution of the x-ray converters used in conventional MV AMFPIs with thick, segmented crystalline scintillators designed for dual-energy operation, coupled with the addition of x-ray imaging beams that contain a significant diagnostic component. A second approach involves introduction of a large area, monolithic array of photon counting pixels with multiple energy thresholds and event counters, which could provide multi-spectral views of the treatment beam with improved contrast. In this paper, the motivations behind, and the merits of each approach are described. In addition, prospects for such dual-energy imagers and photon counting array designs are discussed in the context of the radiotherapy environment.

  5. Calorimetric determination of kQ factors for NE 2561 and NE 2571 ionization chambers in 5 cm × 5 cm and 10 cm × 10 cm radiotherapy beams of 8 MV and 16 MV photons

    NASA Astrophysics Data System (ADS)

    Krauss, Achim; Kapsch, Ralf-Peter

    2007-10-01

    The relative uncertainty of the ionometric determination of the absorbed dose to water, Dw, in the reference dosimetry of high-energy photon beams is in the order of 1.5% and is dominated by the uncertainty of the calculated chamber- and energy-dependent correction factors kQ. In the present investigation, kQ values were determined experimentally in 5 cm × 5 cm and 10 cm × 10 cm radiotherapy beams of 8 MV and 16 MV bremsstrahlung by means of a water calorimeter operated at 4 °C. Ionization chambers of the types NE 2561 and NE 2571 were calibrated directly in the water phantom of the calorimeter. The measurements were carried out at the linear accelerator of the Physikalisch-Technische Bundesanstalt. It is shown that the kQ factor of a single ionization chamber can be measured with a standard uncertainty of less than 0.3%. No significant variations of kQ were found for the different lateral sizes of the radiation fields used in this investigation.

  6. Esthesioneuroblastoma treated with external radiotherapy. Case report

    PubMed Central

    Tramacere, F; Bambace, S; De Luca, MC; Castagna, R; Francavilla, MC; Leone, A; Monastero, S; Fucilli, F; Pili, G; Portaluri, M

    2008-01-01

    Summary Esthesioneuroblastoma is a rare tumour arising from the olfactory epithelium of the nasal vault which frequently invades the cranial base and orbit. Esthesioneuroblastoma has a bimodal age distribution between 11 and 20 years and between 51 and 60 years. Esthesioneuroblastoma accounts for approximately 1-5% of intranasal cancers. The case is reported of a 79-year-old female patient with a Kadish stage C tumour with a one-year history of headache, nasal obstruction, anosmia, rhinorrhoea and epistaxis. Aim of this study is to analyse the natural history, treatment and prognosis of this tumour, based on a review of the literature. PMID:18939712

  7. EXTERNAL INVERSE COMPTON SPECTRA FOR MONOENERGETIC AND BLACKBODY PHOTON FIELDS UPSCATTERED BY A POWER-LAW ELECTRON DISTRIBUTION WITH A FINITE ENERGY RANGE

    SciTech Connect

    Fouka, M.; Ouichaoui, S. E-mail: souichaoui@usthb.dz

    2011-08-20

    We have calculated the inverse Compton (IC) integrated spectral power within the Thomson limit for a monoenergetic isotropic photon field upscattered off highly relativistic electrons assuming an isotropic power-law distribution of the latter, N({gamma}) = C{gamma}{sup -p}, with Lorentz parameter values {gamma}{sub 1} < {gamma} < {gamma}{sub 2}. Our interest was essentially focused on the case of a finite energy range (finite {gamma}{sub 2}) possibly having realistic applications in high-energy astrophysical sites, mainly relativistic shock regions. To this end, we have defined and derived a dimensionless parametric function, F{sub p} (z{sub 1}, {eta}), with variables z{sub 1} = {epsilon}{sub 1}/4{gamma}{sup 2}{sub 1}{epsilon} and {eta} = {gamma}{sub 2}/{gamma}{sub 1}. This result was used to derive the IC-integrated spectral power for an upscattered blackbody (BB) photon field using a dimensionless parametric function, W{sub p} ({xi}, {eta}), with variable {xi} = {epsilon}{sub 1}/4{gamma}{sup 2}{sub 1} kT. Asymptotic forms of this function have been derived for three energy ranges, i.e., {xi} << 1, 1 << {xi} << {eta}{sup 2}, and {xi} >> {eta}{sup 2}. Then, a characteristic value, {eta}{sub c}(p, {epsilon}) with {epsilon} << 1, of parameter {eta} was defined such that the middle range asymptotic form of W{sub p} ({xi}, {eta}) could be valid and good when {eta} {approx}> {eta}{sub c}(p, {epsilon}), by deriving an approximate expression of this particular value for {epsilon} = 10{sup -3}. The resulting spectra featured by a high-energy cutoff in the case of low values of the ratio {eta} can be discussed at least for a population of short gamma-ray bursts (GRBs), those best described by the cutoff power-law model with a low-energy spectral index, {alpha} {approx} 0. Furthermore, it is suggested that for GRB spectra with {alpha} < -1/2 pertaining to the prompt emission phase, the IC is a likely emission mechanism for both monoenergetic and BB photon fields if one

  8. Midline Dose Verification with Diode In Vivo Dosimetry for External Photon Therapy of Head and Neck and Pelvis Cancers During Initial Large-Field Treatments

    SciTech Connect

    Tung, Chuan-Jong; Yu, Pei-Chieh; Chiu, Min-Chi; Yeh, Chi-Yuan; Lee, Chung-Chi; Chao, Tsi-Chian

    2010-01-01

    During radiotherapy treatments, quality assurance/control is essential, particularly dose delivery to patients. This study was designed to verify midline doses with diode in vivo dosimetry. Dosimetry was studied for 6-MV bilateral fields in head and neck cancer treatments and 10-MV bilateral and anteroposterior/posteroanterior (AP/PA) fields in pelvic cancer treatments. Calibrations with corrections of diodes were performed using plastic water phantoms; 190 and 100 portals were studied for head and neck and pelvis treatments, respectively. Calculations of midline doses were made using the midline transmission, arithmetic mean, and geometric mean algorithms. These midline doses were compared with the treatment planning system target doses for lateral or AP (PA) portals and paired opposed portals. For head and neck treatments, all 3 algorithms were satisfactory, although the geometric mean algorithm was less accurate and more uncertain. For pelvis treatments, the arithmetic mean algorithm seemed unacceptable, whereas the other algorithms were satisfactory. The random error was reduced by using averaged midline doses of paired opposed portals because the asymmetric effect was averaged out. Considering the simplicity of in vivo dosimetry, the arithmetic mean and geometric mean algorithm should be adopted for head/neck and pelvis treatments, respectively.

  9. Scattered radiation from dental metallic crowns in head and neck radiotherapy.

    PubMed

    Shimozato, T; Igarashi, Y; Itoh, Y; Yamamoto, N; Okudaira, K; Tabushi, K; Obata, Y; Komori, M; Naganawa, S; Ueda, M

    2011-09-01

    We aimed to estimate the scattered radiation from dental metallic crowns during head and neck radiotherapy by irradiating a jaw phantom with external photon beams. The phantom was composed of a dental metallic plate and hydroxyapatite embedded in polymethyl methacrylate. We used radiochromic film measurement and Monte Carlo simulation to calculate the radiation dose and dose distribution inside the phantom. To estimate dose variations in scattered radiation under different clinical situations, we altered the incident energy, field size, plate thickness, plate depth and plate material. The simulation results indicated that the dose at the incident side of the metallic dental plate was approximately 140% of that without the plate. The differences between dose distributions calculated with the radiation treatment-planning system (TPS) algorithms and the data simulation, except around the dental metallic plate, were 3% for a 4 MV photon beam. Therefore, we should carefully consider the dose distribution around dental metallic crowns determined by a TPS. PMID:21813962

  10. Monte Carlo Calculation of the Response of an External Detector to a Photon Source in the Lungs of a Heterogeneous Phantom.

    Energy Science and Technology Software Center (ESTSC)

    1980-05-19

    FANTOM calculates the response of a 20-cm-diameter phoswich (3 mm NaI(Tl) primary detector) to a source of low energy photons distributed in the lungs of a heterogeneous MIRD phantom, approximating ICRP Reference Man. The program considers the trunk region of the MIRD phantom which is made up of three types of tissues with different densities: skeletal tissue (1.85), lung tissue (0.3) and soft tissue (1). Each organ in the thorax region is described by simplemore » quadratic equations, with respect to a Cartesian coordinate system (X,Y,Z), the origin of which is located at the center of the base of the trunk, with positive Z-axis, Y-axis, and X-axis directed toward the head, posterior, and left side of the phantom, respectively.« less

  11. Development and implementation in the Monte Carlo code PENELOPE of a new virtual source model for radiotherapy photon beams and portal image calculation.

    PubMed

    Chabert, I; Barat, E; Dautremer, T; Montagu, T; Agelou, M; Croc de Suray, A; Garcia-Hernandez, J C; Gempp, S; Benkreira, M; de Carlan, L; Lazaro, D

    2016-07-21

    This work aims at developing a generic virtual source model (VSM) preserving all existing correlations between variables stored in a Monte Carlo pre-computed phase space (PS) file, for dose calculation and high-resolution portal image prediction. The reference PS file was calculated using the PENELOPE code, after the flattening filter (FF) of an Elekta Synergy 6 MV photon beam. Each particle was represented in a mobile coordinate system by its radial position (r s ) in the PS plane, its energy (E), and its polar and azimuthal angles (φ d and θ d ), describing the particle deviation compared to its initial direction after bremsstrahlung, and the deviation orientation. Three sub-sources were created by sorting out particles according to their last interaction location (target, primary collimator or FF). For each sub-source, 4D correlated-histograms were built by storing E, r s , φ d and θ d values. Five different adaptive binning schemes were studied to construct 4D histograms of the VSMs, to ensure histogram efficient handling as well as an accurate reproduction of E, r s , φ d and θ d distribution details. The five resulting VSMs were then implemented in PENELOPE. Their accuracy was first assessed in the PS plane, by comparing E, r s , φ d and θ d distributions with those obtained from the reference PS file. Second, dose distributions computed in water, using the VSMs and the reference PS file located below the FF, and also after collimation in both water and heterogeneous phantom, were compared using a 1.5%-0 mm and a 2%-0 mm global gamma index, respectively. Finally, portal images were calculated without and with phantoms in the beam. The model was then evaluated using a 1%-0 mm global gamma index. Performance of a mono-source VSM was also investigated and led, as with the multi-source model, to excellent results when combined with an adaptive binning scheme. PMID:27353090

  12. Development and implementation in the Monte Carlo code PENELOPE of a new virtual source model for radiotherapy photon beams and portal image calculation

    NASA Astrophysics Data System (ADS)

    Chabert, I.; Barat, E.; Dautremer, T.; Montagu, T.; Agelou, M.; Croc de Suray, A.; Garcia-Hernandez, J. C.; Gempp, S.; Benkreira, M.; de Carlan, L.; Lazaro, D.

    2016-07-01

    This work aims at developing a generic virtual source model (VSM) preserving all existing correlations between variables stored in a Monte Carlo pre-computed phase space (PS) file, for dose calculation and high-resolution portal image prediction. The reference PS file was calculated using the PENELOPE code, after the flattening filter (FF) of an Elekta Synergy 6 MV photon beam. Each particle was represented in a mobile coordinate system by its radial position (r s ) in the PS plane, its energy (E), and its polar and azimuthal angles (φ d and θ d ), describing the particle deviation compared to its initial direction after bremsstrahlung, and the deviation orientation. Three sub-sources were created by sorting out particles according to their last interaction location (target, primary collimator or FF). For each sub-source, 4D correlated-histograms were built by storing E, r s , φ d and θ d values. Five different adaptive binning schemes were studied to construct 4D histograms of the VSMs, to ensure histogram efficient handling as well as an accurate reproduction of E, r s , φ d and θ d distribution details. The five resulting VSMs were then implemented in PENELOPE. Their accuracy was first assessed in the PS plane, by comparing E, r s , φ d and θ d distributions with those obtained from the reference PS file. Second, dose distributions computed in water, using the VSMs and the reference PS file located below the FF, and also after collimation in both water and heterogeneous phantom, were compared using a 1.5%–0 mm and a 2%–0 mm global gamma index, respectively. Finally, portal images were calculated without and with phantoms in the beam. The model was then evaluated using a 1%–0 mm global gamma index. Performance of a mono-source VSM was also investigated and led, as with the multi-source model, to excellent results when combined with an adaptive binning scheme.

  13. Thermoluminescence of Ge- and Al-Doped SiO2 Optical Fibers Subjected to 0.2-4.0 Gy External Photon Radiotherapeutic Dose

    NASA Astrophysics Data System (ADS)

    Hossain, I.; Wagiran, H.; Yaakob, N. H.

    2013-09-01

    In this work, we studied the thermoluminescence response of Ge- and Al-doped optical fibers, its linearity, energy dependence, and sensitivity. The Ge-doped optical fibers demonstrate useful TL properties and represent an excellent candidate for use in TL dosimetry of ionizing radiation. The TL response increases monotonically over a wide photon dose range, from 0.2 Gy to 4.0 Gy. The TL results for these fibers have been compared with similar TL data for phosphor TLD-100. Commercially available Al- and Ge-doped optical fibers have both been found to yield a linear dose-TL signal relationship, although the Al-doped fiber provides only 5 % of the sensitivity of the Ge-doped fibers. The TL characteristics of Ge-doped optical fiber, plus its small size (125 μm diameter), high flexibility, ease of handling, and low cost compared with other TL materials, make this commercial optical fiber a very promising TL material for use in medicine, industry, reactor operation, and a variety of other areas.

  14. Dose to 'water-like' media or dose to tissue in MV photons radiotherapy treatment planning: still a matter of debate.

    PubMed

    Andreo, Pedro

    2015-01-01

    The difference between Monte Carlo Treatment Planning (MCTP) based on the assumption of 'water-like' tissues with densities obtained from CT procedures, or on tissue compositions derived from CT-determined densities, have been investigated. Stopping powers and electron fluences have been calculated for a range of media and body tissues for 6 MV photon beams, including changes in their physical data (density and stopping powers). These quantities have been used to determine absorbed doses using cavity theory. It is emphasized that tissue compositions given in ICRU or ICRP reports should not be given the standing of physical constants as they correspond to average values obtained for a limited number of human-body samples. It has been shown that mass stopping-power ratios to water are more dependent on patient-to-patient composition differences, and therefore on their mean excitation energies (I-values), than on mass density. Electron fluence in different media are also more dependent on media composition (and their I-values) than on density. However, as a consequence of the balance between fluence and stopping powers, doses calculated from their product are more constant than what the independent stopping powers and fluence variations suggest. Additionally, cancelations in dose ratios minimize the differences between the 'water-like' and 'tissue' approaches, yielding practically identical results except for bone, and to a lesser extent for adipose tissue. A priori, changing from one approach to another does not seem to be justified considering the large number of approximations and uncertainties involved throughout the treatment planning tissue segmentation and dose calculation procedures. The key issue continues to be the composition of tissues and their I-values, and as these cannot be obtained for individual patients, whatever approach is selected does not lead to significant differences from a water reference dose, the maximum of these being of the order of 5

  15. Dose to ‘water-like’ media or dose to tissue in MV photons radiotherapy treatment planning: still a matter of debate

    NASA Astrophysics Data System (ADS)

    Andreo, Pedro

    2015-01-01

    The difference between Monte Carlo Treatment Planning (MCTP) based on the assumption of ‘water-like’ tissues with densities obtained from CT procedures, or on tissue compositions derived from CT-determined densities, have been investigated. Stopping powers and electron fluences have been calculated for a range of media and body tissues for 6 MV photon beams, including changes in their physical data (density and stopping powers). These quantities have been used to determine absorbed doses using cavity theory. It is emphasized that tissue compositions given in ICRU or ICRP reports should not be given the standing of physical constants as they correspond to average values obtained for a limited number of human-body samples. It has been shown that mass stopping-power ratios to water are more dependent on patient-to-patient composition differences, and therefore on their mean excitation energies (I-values), than on mass density. Electron fluence in different media are also more dependent on media composition (and their I-values) than on density. However, as a consequence of the balance between fluence and stopping powers, doses calculated from their product are more constant than what the independent stopping powers and fluence variations suggest. Additionally, cancelations in dose ratios minimize the differences between the ‘water-like’ and ‘tissue’ approaches, yielding practically identical results except for bone, and to a lesser extent for adipose tissue. A priori, changing from one approach to another does not seem to be justified considering the large number of approximations and uncertainties involved throughout the treatment planning tissue segmentation and dose calculation procedures. The key issue continues to be the composition of tissues and their I-values, and as these cannot be obtained for individual patients, whatever approach is selected does not lead to significant differences from a water reference dose, the maximum of these being of the

  16. Dosimetric comparison of Monte Carlo codes (EGS4, MCNP, MCNPX) considering external and internal exposures of the Zubal phantom to electron and photon sources.

    PubMed

    Chiavassa, S; Lemosquet, A; Aubineau-Lanièce, I; de Carlan, L; Clairand, I; Ferrer, L; Bardiès, M; Franck, D; Zankl, M

    2005-01-01

    This paper aims at comparing dosimetric assessments performed with three Monte Carlo codes: EGS4, MCNP4c2 and MCNPX2.5e, using a realistic voxel phantom, namely the Zubal phantom, in two configurations of exposure. The first one deals with an external irradiation corresponding to the example of a radiological accident. The results are obtained using the EGS4 and the MCNP4c2 codes and expressed in terms of the mean absorbed dose (in Gy per source particle) for brain, lungs, liver and spleen. The second one deals with an internal exposure corresponding to the treatment of a medullary thyroid cancer by 131I-labelled radiopharmaceutical. The results are obtained by EGS4 and MCNPX2.5e and compared in terms of S-values (expressed in mGy per kBq and per hour) for liver, kidney, whole body and thyroid. The results of these two studies are presented and differences between the codes are analysed and discussed. PMID:16604715

  17. On bolus for megavoltage photon and electron radiation therapy

    SciTech Connect

    Vyas, Vedang; Palmer, Lisa; Mudge, Ray; Jiang, Runqing; Fleck, Andre; Schaly, Bryan; Osei, Ernest; Charland, Paule

    2013-10-01

    Frequently, in radiation therapy one must treat superficial lesions on cancer patients; these are at or adjacent to the skin. Megavoltage photon radiotherapy penetrates through the skin to irradiate deep-seated tumors, with skin-sparing property. Hence, to treat superficial lesions, one must use a layer of scattering material to feign as the skin surface. Although megavoltage electron beams are used for superficial treatments, one occasionally needs to enhance the dose near the surface. Such is the function of a “bolus,” a natural or synthetically developed material that acts as a layer of tissue to provide a more effective treatment to the superficial lesions. Other uses of boluses are to correct for varying surface contours and to add scattering material around the patient's surface. Materials used as bolus vary from simple water to metal and include various mixtures and compounds. Even with the modernization of the technology for external-beam therapy and the emergence of various commercial boluses, the preparation and utilization of a bolus in clinical radiotherapy remains an art. Considering the varying experiences and practices, this paper briefly summarizes available boluses that have been proposed and are employed in clinical radiotherapy. Although this review is not exhaustive, it provides some initial guidance and answers questions that may arise in clinical practice.

  18. Commissioning of intensity modulated neutron radiotherapy (IMNRT)

    SciTech Connect

    Burmeister, Jay; Snyder, Michael; Spink, Robyn; Liang Liang; Bossenberger, Todd; Halford, Robert; Brandon, John; Delauter, Jonathan

    2013-02-15

    Purpose: Intensity modulated neutron radiotherapy (IMNRT) has been developed using inhouse treatment planning and delivery systems at the Karmanos Cancer Center/Wayne State University Fast Neutron Therapy facility. The process of commissioning IMNRT for clinical use is presented here. Results of commissioning tests are provided including validation measurements using representative patient plans as well as those from the TG-119 test suite. Methods: IMNRT plans were created using the Varian Eclipse optimization algorithm and an inhouse planning system for calculation of neutron dose distributions. Tissue equivalent ionization chambers and an ionization chamber array were used for point dose and planar dose distribution comparisons with calculated values. Validation plans were delivered to water and virtual water phantoms using TG-119 measurement points and evaluation techniques. Photon and neutron doses were evaluated both inside and outside the target volume for a typical IMNRT plan to determine effects of intensity modulation on the photon dose component. Monitor unit linearity and effects of beam current and gantry angle on output were investigated, and an independent validation of neutron dosimetry was obtained. Results: While IMNRT plan quality is superior to conventional fast neutron therapy plans for clinical sites such as prostate and head and neck, it is inferior to photon IMRT for most TG-119 planning goals, particularly for complex cases. This results significantly from current limitations on the number of segments. Measured and calculated doses for 11 representative plans (six prostate/five head and neck) agreed to within -0.8 {+-} 1.4% and 5.0 {+-} 6.0% within and outside the target, respectively. Nearly all (22/24) ion chamber point measurements in the two phantom arrangements were within the respective confidence intervals for the quantity [(measured-planned)/prescription dose] derived in TG-119. Mean differences for all measurements were 0.5% (max

  19. Photon-photon collisions

    SciTech Connect

    Burke, D.L.

    1982-10-01

    Studies of photon-photon collisions are reviewed with particular emphasis on new results reported to this conference. These include results on light meson spectroscopy and deep inelastic e..gamma.. scattering. Considerable work has now been accumulated on resonance production by ..gamma gamma.. collisions. Preliminary high statistics studies of the photon structure function F/sub 2//sup ..gamma../(x,Q/sup 2/) are given and comments are made on the problems that remain to be solved.

  20. Monte Carlo Study of Radiation Dose Enhancement by Gadolinium in Megavoltage and High Dose Rate Radiotherapy

    PubMed Central

    Zhang, Daniel G.; Feygelman, Vladimir; Moros, Eduardo G.; Latifi, Kujtim; Zhang, Geoffrey G.

    2014-01-01

    MRI is often used in tumor localization for radiotherapy treatment planning, with gadolinium (Gd)-containing materials often introduced as a contrast agent. Motexafin gadolinium is a novel radiosensitizer currently being studied in clinical trials. The nanoparticle technologies can target tumors with high concentration of high-Z materials. This Monte Carlo study is the first detailed quantitative investigation of high-Z material Gd-induced dose enhancement in megavoltage external beam photon therapy. BEAMnrc, a radiotherapy Monte Carlo simulation package, was used to calculate dose enhancement as a function of Gd concentration. Published phase space files for the TrueBeam flattening filter free (FFF) and conventional flattened 6MV photon beams were used. High dose rate (HDR) brachytherapy with Ir-192 source was also investigated as a reference. The energy spectra difference caused a dose enhancement difference between the two beams. Since the Ir-192 photons have lower energy yet, the photoelectric effect in the presence of Gd leads to even higher dose enhancement in HDR. At depth of 1.8 cm, the percent mean dose enhancement for the FFF beam was 0.38±0.12, 1.39±0.21, 2.51±0.34, 3.59±0.26, and 4.59±0.34 for Gd concentrations of 1, 5, 10, 15, and 20 mg/mL, respectively. The corresponding values for the flattened beam were 0.09±0.14, 0.50±0.28, 1.19±0.29, 1.68±0.39, and 2.34±0.24. For Ir-192 with direct contact, the enhanced were 0.50±0.14, 2.79±0.17, 5.49±0.12, 8.19±0.14, and 10.80±0.13. Gd-containing materials used in MRI as contrast agents can also potentially serve as radiosensitizers in radiotherapy. This study demonstrates that Gd can be used to enhance radiation dose in target volumes not only in HDR brachytherapy, but also in 6 MV FFF external beam radiotherapy, but higher than the currently used clinical concentration (>5 mg/mL) would be needed. PMID:25275550

  1. The use of low energy, ion induced nuclear reactions for proton radiotherapy applications

    SciTech Connect

    Horn, K.M.; Doyle, B.; Segal, M.N.; Hamm, R.W.; Adler, R.J.; Glatstein, E.

    1995-04-01

    Medical radiotherapy has traditionally relied upon the use of external photon beams and internally implanted radioisotopes as the chief means of irradiating tumors. However, advances in accelerator technology and the exploitation of novel means of producing radiation may provide useful alternatives to some current modes of medical radiation delivery with reduced total dose to surrounding healthy tissue, reduced expense, or increased treatment accessibility. This paper will briefly overview currently established modes of radiation therapy, techniques still considered experimental but in clinical use, innovative concepts under study that may enable new forms of treatment or enhance existing ones. The potential role of low energy, ion-induced nuclear reactions in radiotherapy applications is examined specifically for the 650 keV d({sup 3}He,p){sup 4}He nuclear reaction. This examination will describe the basic physics associated with this reaction`s production of 17.4 MeV protons and the processes used to fabricate the necessary materials used in the technique. Calculations of the delivered radiation dose, heat generation, and required exposure times are presented. Experimental data are also presented validating the dose calculations. The design of small, lower cost ion accelerators, as embodied in `nested`-tandem and radio frequency quadrupole accelerators is examined, as is the potential use of high-output {sup 3}He and deuterium ion sources. Finally, potential clinical applications are discussed in terms of the advantages and disadvantages of this technique with respect to current radiotherapy methods and equipment.

  2. Monte Carlo Treatment Planning for Molecular Targeted Radiotherapy within the MINERVA System

    SciTech Connect

    Lehmann, J; Siantar, C H; Wessol, D E; Wemple, C A; Nigg, D; Cogliati, J; Daly, T; Descalle, M; Flickinger, T; Pletcher, D; DeNardo, G

    2004-09-22

    The aim of this project is to extend accurate and patient-specific treatment planning to new treatment modalities, such as molecular targeted radiation therapy, incorporating previously crafted and proven Monte Carlo and deterministic computation methods. A flexible software environment is being created that allows planning radiation treatment for these new modalities and combining different forms of radiation treatment with consideration of biological effects. The system uses common input interfaces, medical image sets for definition of patient geometry, and dose reporting protocols. Previously, the Idaho National Engineering and Environmental Laboratory (INEEL), Montana State University (MSU), and Lawrence Livermore National Laboratory (LLNL) had accrued experience in the development and application of Monte Carlo-based, three-dimensional, computational dosimetry and treatment planning tools for radiotherapy in several specialized areas. In particular, INEEL and MSU have developed computational dosimetry systems for neutron radiotherapy and neutron capture therapy, while LLNL has developed the PEREGRINE computational system for external beam photon-electron therapy. Building on that experience, the INEEL and MSU are developing the MINERVA (Modality Inclusive Environment for Radiotherapeutic Variable Analysis) software system as a general framework for computational dosimetry and treatment planning for a variety of emerging forms of radiotherapy. In collaboration with this development, LLNL has extended its PEREGRINE code to accommodate internal sources for molecular targeted radiotherapy (MTR), and has interfaced it with the plug-in architecture of MINERVA. Results from the extended PEREGRINE code have been compared to published data from other codes, and found to be in general agreement (EGS4 - 2%, MCNP - 10%)(Descalle et al. 2003). The code is currently being benchmarked against experimental data. The interpatient variability of the drug pharmacokinetics in MTR

  3. Monte Carlo treatment planning for molecular targeted radiotherapy within the MINERVA system.

    PubMed

    Lehmann, Joerg; Hartmann Siantar, Christine; Wessol, Daniel E; Wemple, Charles A; Nigg, David; Cogliati, Josh; Daly, Tom; Descalle, Marie-Anne; Flickinger, Terry; Pletcher, David; Denardo, Gerald

    2005-03-01

    The aim of this project is to extend accurate and patient-specific treatment planning to new treatment modalities, such as molecular targeted radiation therapy, incorporating previously crafted and proven Monte Carlo and deterministic computation methods. A flexible software environment is being created that allows planning radiation treatment for these new modalities and combining different forms of radiation treatment with consideration of biological effects. The system uses common input interfaces, medical image sets for definition of patient geometry and dose reporting protocols. Previously, the Idaho National Engineering and Environmental Laboratory (INEEL), Montana State University (MSU) and Lawrence Livermore National Laboratory (LLNL) had accrued experience in the development and application of Monte Carlo based, three-dimensional, computational dosimetry and treatment planning tools for radiotherapy in several specialized areas. In particular, INEEL and MSU have developed computational dosimetry systems for neutron radiotherapy and neutron capture therapy, while LLNL has developed the PEREGRINE computational system for external beam photon-electron therapy. Building on that experience, the INEEL and MSU are developing the MINERVA (modality inclusive environment for radiotherapeutic variable analysis) software system as a general framework for computational dosimetry and treatment planning for a variety of emerging forms of radiotherapy. In collaboration with this development, LLNL has extended its PEREGRINE code to accommodate internal sources for molecular targeted radiotherapy (MTR), and has interfaced it with the plugin architecture of MINERVA. Results from the extended PEREGRINE code have been compared to published data from other codes, and found to be in general agreement (EGS4-2%, MCNP-10%) (Descalle et al 2003 Cancer Biother. Radiopharm. 18 71-9). The code is currently being benchmarked against experimental data. The interpatient variability of the

  4. Imaging Instrumentation and Techniques for Precision Radiotherapy

    NASA Astrophysics Data System (ADS)

    Parodi, Katia; Parodi, Katia; Thieke, Christian; Thieke, Christian

    Over the last decade, several technological advances have considerably improved the achievable precision of dose delivery in radiation therapy. Clinical exploitation of the superior tumor-dose conformality offered by modern radiotherapy techniques like intensity-modulated radiotherapy and ion beam therapy requires morphological and functional assessment of the tumor during the entire therapy chain from treatment planning to beam application and treatment response evaluation. This chapter will address the main rationale and role of imaging in state-of-the-art external beam radiotherapy. Moreover, it will present the status of novel imaging instrumentation and techniques being nowadays introduced in clinical use or still under development for image guidance and, ultimately, dose guidance of precision radiotherapy.

  5. Photon-photon collisions

    SciTech Connect

    Brodsky, S.J.

    1988-07-01

    Highlights of the VIIIth International Workshop on Photon-Photon Collisions are reviewed. New experimental and theoretical results were reported in virtually every area of ..gamma gamma.. physics, particularly in exotic resonance production and tests of quantum chromodynamics where asymptotic freedom and factorization theorems provide predictions for both inclusive and exclusive ..gamma gamma.. reactions at high momentum transfer. 73 refs., 12 figs.

  6. Dosimetric Study of Current Treatment Options for Radiotherapy in Retinoblastoma

    SciTech Connect

    Eldebawy, Eman; Parker, William; Abdel Rahman, Wamied; Freeman, Carolyn R.

    2012-03-01

    Purpose: To determine the best treatment technique for patients with retinoblastoma requiring radiotherapy to the whole eye. Methods and Materials: Treatment plans for 3 patients with retinoblastoma were developed using 10 radiotherapy techniques including electron beams, photon beam wedge pair (WP), photon beam three-dimensional conformal radiotherapy (3D-CRT), fixed gantry intensity-modulated radiotherapy (IMRT), photon volumetric arc therapy (VMAT), fractionated stereotactic radiotherapy, and helical tomotherapy (HT). Dose-volume analyses were carried out for each technique. Results: All techniques provided similar target coverage; conformity was highest for VMAT, nine-field (9F) IMRT, and HT (conformity index [CI] = 1.3) and lowest for the WP and two electron techniques (CI = 1.8). The electron techniques had the highest planning target volume dose gradient (131% of maximum dose received [D{sub max}]), and the CRT techniques had the lowest (103% D{sub max}) gradient. The volume receiving at least 20 Gy (V{sub 20Gy}) for the ipsilateral bony orbit was lowest for the VMAT and HT techniques (56%) and highest for the CRT techniques (90%). Generally, the electron beam techniques were superior in terms of brain sparing and delivered approximately one-third of the integral dose of the photon techniques. Conclusions: Inverse planned image-guided radiotherapy delivered using HT or VMAT gives better conformity index, improved orbital bone and brain sparing, and a lower integral dose than other techniques.

  7. SU-E-T-571: Newly Emerging Integrated Transmission Detector Systems Provide Online Quality Assurance of External Beam Radiation Therapy

    SciTech Connect

    Hoffman, D; Chung, E; Hess, C; Stern, R; Benedict, S

    2015-06-15

    Purpose: Two newly emerging transmission detectors positioned upstream from the patient have been evaluated for online quality assurance of external beam radiotherapy. The prototype for the Integral Quality Monitor (IQM), developed by iRT Systems GmbH (Koblenz, Germany) is a large-area ion chamber mounted on the linac accessory tray to monitor photon fluence, energy, beam shape, and gantry position during treatment. The ion chamber utilizes a thickness gradient which records variable response dependent on beam position. The prototype of Delta4 Discover™, developed by ScandiDos (Uppsala, Sweden) is a linac accessory tray mounted 4040 diode array that measures photon fluence during patient treatment. Both systems are employable for patient specific QA prior to treatment delivery. Methods: Our institution evaluated the reproducibility of measurements using various beam types, including VMAT treatment plans with both the IQM ion chamber and the Delta4 Discover diode array. Additionally, the IQM’s effect on photon fluence, dose response, simulated beam error detection, and the accuracy of the integrated barometer, thermometer, and inclinometer were characterized. The evaluated photon beam errors are based on the annual tolerances specified in AAPM TG-142. Results: Repeated VMAT treatments were measured with 0.16% reproducibility by the IQM and 0.55% reproducibility by the Delta4 Discover. The IQM attenuated 6, 10, and 15 MV photon beams by 5.43±0.02%, 4.60±0.02%, and 4.21±0.03% respectively. Photon beam profiles were affected <1.5% in the non-penumbra regions. The IQM’s ion chamber’s dose response was linear and the thermometer, barometer, and inclinometer agreed with other calibrated devices. The device detected variations in monitor units delivered (1%), field position (3mm), single MLC leaf positions (13mm), and photon energy. Conclusion: We have characterized two new transmissions detector systems designed to provide in-vivo like measurements upstream

  8. Radiotherapy Dose Perturbation of Esophageal Stents Examined in an Experimental Model

    SciTech Connect

    Atwood, Todd F.; Hsu, Annie; Ogara, Maydeen M.; Luba, Daniel G.; Tamler, Bradley J.; DiSario, James A.; Maxim, Peter G.

    2012-04-01

    Purpose: To investigate the radiotherapy dose perturbations caused by esophageal stents in patients undergoing external beam treatments for esophageal cancer. Methods and Materials: Four esophageal stents were examined (three metallic stents: WallFlex, Ultraflex, and Alveolus; one nonmetallic stent with limited radiopaque markers for visualization: Polyflex). All experiments were performed in a liquid water phantom with a custom acrylic stent holder. Radiochromic film was used to measure the dose distributions adjacent to the stents at locations proximal and distal to the radiation source. The stents were placed in an air-filled cavity to simulate the esophagus. Treatment plans were created and delivered for photon energies of 6 and 15 MV, and data analysis was performed on uniform regions of interest, according to the size and geometric placement of the films, to quantify the dose perturbations. Results: The three metallic stents produced the largest dose perturbations with distinct patterns of 'hot' spots (increased dose) measured proximal to the radiation source (up to 15.4%) and both 'cold' (decreased dose) and hot spots measured distal to the radiation source (range, -6.1%-5.8%). The polymeric Polyflex stent produced similar dose perturbations when the radiopaque markers were examined (range, -7.6%-15.4%). However, when the radiopaque markers were excluded from the analysis, the Polyflex stent produced significantly smaller dose perturbations, with maximum hot spots of 7.3% and cold spots of -3.2%. Conclusions: The dose perturbations caused by esophageal stents during the treatment of esophageal cancer using external beam radiotherapy should be understood. These perturbations will result in hot and cold spots in the esophageal mucosa, with varying magnitudes depending on the stent. The nonmetallic Polyflex stent appears to be the most suitable for patients undergoing radiotherapy, but further studies are necessary to determine the clinical significance of the

  9. Photon-photon collisions

    SciTech Connect

    Brodsky, S.J.

    1985-01-01

    The study of photon-photon collisions has progressed enormously, stimulated by new data and new calculational tools for QCD. In the future we can expect precise determinations of ..cap alpha../sub s/ and ..lambda../sup ms/ from the ..gamma..*..gamma.. ..-->.. ..pi../sup 0/ form factor and the photon structure function, as well as detailed checks of QCD, determination of the shape of the hadron distribution amplitudes from ..gamma gamma.. ..-->.. H anti H, reconstruction of sigma/sub ..gamma gamma../ from exclusive channels at low W/sub ..gamma gamma../, definitive studies of high p/sub T/ hadron and jet production, and studies of threshold production of charmed systems. Photon-photon collisions, along with radiative decays of the psi and UPSILON, are ideal for the study of multiquark and gluonic resonances. We have emphasized the potential for resonance formation near threshold in virtually every hadronic exclusive channel, including heavy quark states c anti c c anti c, c anti c u anti u, etc. At higher energies SLC, LEP, ...) parity-violating electroweak effects and Higgs production due to equivalent Z/sup 0/ and W/sup + -/ beams from e ..-->.. eZ/sup 0/ and e ..-->.. nu W will become important. 44 references.

  10. Time to demand dosimetry for molecular radiotherapy?

    PubMed Central

    Guy, M J

    2015-01-01

    Molecular radiotherapy (MRT) has been used clinically for around 75 years. Despite this long history of clinical use, there is no established dosimetry practice for calculating the absorbed dose delivered to tumour targets or to organs at risk. As a result, treatment protocols have often evolved based on experience with relatively small numbers of patients, each receiving a similar administered activity but, potentially, widely varying doses. This is in stark contrast to modern external-beam radiotherapy practice. This commentary describes some of the barriers to MRT dosimetry and gives some opinions on the way forward. PMID:25571916

  11. TOPICAL REVIEW Dosimetry for ion beam radiotherapy

    NASA Astrophysics Data System (ADS)

    Karger, Christian P.; Jäkel, Oliver; Palmans, Hugo; Kanai, Tatsuaki

    2010-11-01

    Recently, ion beam radiotherapy (including protons as well as heavier ions) gained considerable interest. Although ion beam radiotherapy requires dose prescription in terms of iso-effective dose (referring to an iso-effective photon dose), absorbed dose is still required as an operative quantity to control beam delivery, to characterize the beam dosimetrically and to verify dose delivery. This paper reviews current methods and standards to determine absorbed dose to water in ion beam radiotherapy, including (i) the detectors used to measure absorbed dose, (ii) dosimetry under reference conditions and (iii) dosimetry under non-reference conditions. Due to the LET dependence of the response of films and solid-state detectors, dosimetric measurements are mostly based on ion chambers. While a primary standard for ion beam radiotherapy still remains to be established, ion chamber dosimetry under reference conditions is based on similar protocols as for photons and electrons although the involved uncertainty is larger than for photon beams. For non-reference conditions, dose measurements in tissue-equivalent materials may also be necessary. Regarding the atomic numbers of the composites of tissue-equivalent phantoms, special requirements have to be fulfilled for ion beams. Methods for calibrating the beam monitor depend on whether passive or active beam delivery techniques are used. QA measurements are comparable to conventional radiotherapy; however, dose verification is usually single field rather than treatment plan based. Dose verification for active beam delivery techniques requires the use of multi-channel dosimetry systems to check the compliance of measured and calculated dose for a representative sample of measurement points. Although methods for ion beam dosimetry have been established, there is still room for developments. This includes improvement of the dosimetric accuracy as well as development of more efficient measurement techniques.

  12. Phase II Trial of Radiation Dose Escalation With Conformal External Beam Radiotherapy and High-Dose-Rate Brachytherapy Combined With Long-Term Androgen Suppression in Unfavorable Prostate Cancer: Feasibility Report

    SciTech Connect

    Valero, Jeanette; Cambeiro, Mauricio; Galan, Carlos; Teijeira, Mercedes; Romero, Pilar; Zudaire, Javier; Moreno, Marta; Ciervide, Raquel; Aristu, Jose Javier; Martinez-Monge, Rafael

    2010-02-01

    Purpose: To determine the feasibility of combined long-term luteinizing hormone-releasing hormone agonist-based androgen suppressive therapy (AST) and dose escalation with high-dose-rate (HDR) brachytherapy for high-risk (HRPC) or very-high-risk prostate cancer (VHRPC). Methods and Materials: Between January 2001 and October 2006, 134 patients (median age, 70 years) with either National Comprehensive Cancer Network criteria-defined HRPC (n = 47, 35.1%) or VHRPC (n = 87, 64.9%) were prospectively enrolled in this Phase II trial. Tumor characteristics included a median pretreatment prostate-specific antigen level of 14.6 ng/mL, a median clinical stage of T2c, and a median Gleason score of 7. Three-dimensional conformal radiotherapy (54 Gy in 30 fractions) was followed by HDR brachytherapy (19 Gy in 4 b.i.d. treatments). Androgen suppressive therapy started 0-3 months before three-dimensional conformal radiotherapy and continued for 2 years. Results: One implant was repositioned with a new procedure (0.7%). Five patients (3.7%) discontinued AST at a median of 13 months (range, 6-18 months) because of disease progression (n = 1), hot flashes (n = 2), fatigue (n = 1), and impotence (n = 1). After a median follow-up of 37.4 months (range, 24-90 months), the highest Radiation Therapy Oncology Group-defined late urinary toxicities were Grade 0 in 47.8%, Grade 1 in 38.1%, Grade 2 in 7.5%, and Grade 3 in 6.7% of patients. Maximal late gastrointestinal toxicities were Grade 0 in 73.1%, Grade 1 in 16.4%, Grade 2 in 7.5%, and Grade 3 in 2.9% of patients. There were no Grade 4 or 5 events. Conclusions: Intermediate-term results show that dose escalation with HDR brachytherapy combined with long-term AST is feasible and has a toxicity profile similar to that reported by previous HDR brachytherapy studies.

  13. [Palliative Radiotherapy for Bone Metastases].

    PubMed

    Nagakura, Hisayasu

    2015-11-01

    Bone metastasis is associated with many symptoms such as bone pain, pathological fracture, and spinal cord compression. Especially, pain secondary to bone metastases is a serious problem in many patients with metastatic cancer. Radiotherapy can provide remarkable pain relief, reduce the requirement for analgesic drugs, and prevent pathological fracture or spinal cord compression with few complications in most patients. Many randomized controlled trials have shown equivalent extent of pain relief between single-fraction and multiple-fraction regimens. Reirradiation of painful bone metastases is effective for palliation of pain in non-responders or patients with recurrent pain after an initial satisfactory response to a previous radiation therapy. Systemic administration of radioisotopes is an important palliative care option for painful multifocal bone metastases detected on nuclear imaging; however, the application of this option depends on the histologic features of the tumor and distribution of the metastases. Metastatic spinal cord compression is the most frequent oncologic emergency and necessitates timely and appropriate treatment. External beam radiotherapy is commonly used for the treatment of metastatic spinal cord compression. Surgical decompression and stabilization should be considered for metastatic spinal cord compression or pathological fracture in select patients. Postoperative radiotherapy should be administered to patients who have undergone surgical intervention for bone metastases. For patients at a high risk for oncologic emergency, optimal prophylactic management is highly recommended. PMID:26602393

  14. Smart packaging for photonics

    SciTech Connect

    Smith, J.H.; Carson, R.F.; Sullivan, C.T.; McClellan, G.; Palmer, D.W.

    1997-09-01

    Unlike silicon microelectronics, photonics packaging has proven to be low yield and expensive. One approach to make photonics packaging practical for low cost applications is the use of {open_quotes}smart{close_quotes} packages. {open_quotes}Smart{close_quotes} in this context means the ability of the package to actuate a mechanical change based on either a measurement taken by the package itself or by an input signal based on an external measurement. One avenue of smart photonics packaging, the use of polysilicon micromechanical devices integrated with photonic waveguides, was investigated in this research (LDRD 3505.340). The integration of optical components with polysilicon surface micromechanical actuation mechanisms shows significant promise for signal switching, fiber alignment, and optical sensing applications. The optical and stress properties of the oxides and nitrides considered for optical waveguides and how they are integrated with micromechanical devices were investigated.

  15. Pilot Quality Control Program for Audit RT External Beams at Mexican Hospitals

    NASA Astrophysics Data System (ADS)

    Álvarez R., J. T.; Tovar M., V. M.

    2008-08-01

    A pilot quality control program for audit 18 radiotherapy RT external beams at 13 Mexican hospitals is described—for eleven 60 Co beams and seven photon beams of 6, 10 and 15 MV from accelerators. This program contains five parts: a) Preparation of the TLD-100 powder: washing, drying and annealing (one hour 400 °C plus 24 hrs 80 °C). b) Sending two IAEA type capsules to the hospitals for irradiation at the hospital to a nominal DW = 2 Gy ṡ c ) Preparation at the SSDL of ten calibration curves CC in the range of 0.5 Gy to 6 Gy in terms of absorbed dose to water DW for 60 Co with traceability to primary laboratory NRC (Canada), according to a window irradiation: 26/10/2007-7/12/2007. d) Reading all capsules that match their hospital time irradiation and the SSDL window irradiation. f) Evaluation of the Dw imparted by the hospitals.

  16. Intraoperative radiotherapy for breast cancer

    PubMed Central

    Williams, Norman R.; Pigott, Katharine H.; Brew-Graves, Chris

    2014-01-01

    Intra-operative radiotherapy (IORT) as a treatment for breast cancer is a relatively new technique that is designed to be a replacement for whole breast external beam radiotherapy (EBRT) in selected women suitable for breast-conserving therapy. This article reviews twelve reasons for the use of the technique, with a particular emphasis on targeted intra-operative radiotherapy (TARGIT) which uses X-rays generated from a portable device within the operating theatre immediately after the breast tumour (and surrounding margin of healthy tissue) has been removed. The delivery of a single fraction of radiotherapy directly to the tumour bed at the time of surgery, with the capability of adding EBRT at a later date if required (risk-adaptive technique) is discussed in light of recent results from a large multinational randomised controlled trial comparing TARGIT with EBRT. The technique avoids irradiation of normal tissues such as skin, heart, lungs, ribs and spine, and has been shown to improve cosmetic outcome when compared with EBRT. Beneficial aspects to both institutional and societal economics are discussed, together with evidence demonstrating excellent patient satisfaction and quality of life. There is a discussion of the published evidence regarding the use of IORT twice in the same breast (for new primary cancers) and in patients who would never be considered for EBRT because of their special circumstances (such as the frail, the elderly, or those with collagen vascular disease). Finally, there is a discussion of the role of the TARGIT Academy in developing and sustaining high standards in the use of the technique. PMID:25083504

  17. Respiration gated radiotherapy treatment: a technical study

    NASA Astrophysics Data System (ADS)

    Kubo, Hideo D.; Hill, Bruce C.

    1996-01-01

    In order to optimize external-beam conformal radiotherapy, patient movement during treatment must be minimized. For treatment on the upper torso, the target organs are known to move substantially due to patient respiration. This paper deals with the technical aspects of gating the radiotherapy beam synchronously with respiration: the optimal respiration monitoring system, measurements of organ displacement and linear accelerator gating. Several respiration sensors including a thermistor, a thermocouple, a strain gauge and a pneumotachograph were examined to find the optimal sensor. The magnitude of breast, chest wall and lung motion were determined using playback of fluoroscopic x-ray images recorded on a VCR during routine radiotherapy simulation. Total dose, beam symmetry and beam uniformity were examined to determine any effects on the Varian 2100C linear accelerator due to gating.

  18. Antiproton radiotherapy.

    PubMed

    Bassler, Niels; Alsner, Jan; Beyer, Gerd; DeMarco, John J; Doser, Michael; Hajdukovic, Dragan; Hartley, Oliver; Iwamoto, Keisuke S; Jäkel, Oliver; Knudsen, Helge V; Kovacevic, Sandra; Møller, Søren Pape; Overgaard, Jens; Petersen, Jørgen B; Solberg, Timothy D; Sørensen, Brita S; Vranjes, Sanja; Wouters, Bradly G; Holzscheiter, Michael H

    2008-01-01

    extension of TRiP to handle antiproton beams is currently in progress. This will enable us to perform planning studies, where the potential clinical consequences can be examined, and compared to those of other beam modalities such as protons, carbon ions, or IMRT photons. PMID:18158194

  19. Single-Fraction High-Dose-Rate Brachytherapy and Hypofractionated External Beam Radiotherapy for Men With Intermediate-Risk Prostate Cancer: Analysis of Short- and Medium-Term Toxicity and Quality of Life

    SciTech Connect

    Morton, Gerard C.; Loblaw, D. Andrew; Sankreacha, Raxa

    2010-07-01

    Purpose: To determine the short- and medium-term effects of a single high-dose-rate brachytherapy fraction of 15Gy and hypofractionated external beam radiation therapy for prostate cancer. Methods and Materials: Eligible patients had localized prostate cancer with a Gleason score of 7 and a prostate-specific antigen (PSA) concentration of <20 ng/ml or a Gleason score of 6 with a PSA concentration of 10 to 20 ng/ml. Patients received high-dose-rate brachytherapy as a single 15-Gy dose, followed by external beam radiation therapy at 37.5Gy in 15 fractions, and were followed prospectively for toxicity (using Common Terminology Criteria for Adverse Events version 3.0), urinary symptoms (using the International Prostate Symptom Score [IPSS]), erectile function (with the International Index of Erectile Function [IIEF]), and health-related quality of life (with the Expanded Prostate Cancer Index Composite [EPIC]). Clinical examinations and PSA measurements were performed at every visit, and prostate biopsies were repeated at 2 years. The trial accrued 125 patients, with a median follow-up of 1.14 years. Results: Acute grade 2 and 3 genitourinary toxicity occurred in 62% and 1.6% of patients, respectively, and acute grade 2 gastrointestinal toxicity occurred in 6.5% of patients. No grade 3 late toxicity has occurred: 47% of patients had grade 2 genitourinary and 10% of patients had grade 2 gastrointestinal toxicity. Median IPSSs rose from 5 at baseline to 12 at 1 month and returned to 7 at 3 months. Of the total number of patients who were initially potent (IIEF, >21), 8% of patients developed mild to moderate dysfunction, and 27% of patients developed severe erectile dysfunction. Baseline EPIC bowel, urinary, and sexual bother scores decreased by 9, 7, and 19 points, respectively, at 1 year. No patient has experienced biochemical failure, and 16 of the first 17 biopsy results showed no malignancy. Conclusions: Treatment is well tolerated in the short and medium term, with

  20. Quality Assurance in Radiotherapy

    NASA Astrophysics Data System (ADS)

    Mckenzie, Alan

    A common feature of the Radiotherapy Centres where there have been major accidents involving incorrect radiotherapy treatment is that they did not operate good Quality Assurance systems. A Quality Assurance system is sometimes called a Quality Management system, and it is designed to give assurance that quality standards are being met. One of the "spin offs" from operating a Quality Management system is that it reduces the likelihood of a radiotherapy accident. A detailed account of how to set up a quality system in radiotherapy has been given in an ESTRO booklet.2

  1. Virtual and real photons

    NASA Astrophysics Data System (ADS)

    Meulenberg, Andrew, Jr.

    2011-09-01

    Maxwell did not believe in photons. However, his equations lead to electro-magnetic field structures that are considered to be photonic by Quantum ElectroDynamics (QED). They are complete, relativistically correct, and unchallenged after nearly 150 years. However, even though his far-field solution has been considered as the basis for photons, as they stand and are interpreted, they are better fitted to the concept of virtual rather than to real photons. Comparison between staticcharge fields, near-field coupling, and photonic radiation will be made and the distinctions identified. The question of similarities in, and differences between, the two will be addressed. Implied assumptions in Feynman's "Lectures" could lead one to believe that he had provided a general classical electrodynamics proof that an orbital electron must radiate. While his derivation is correct, two of the conditions defined do not always apply in this case. As a result, the potential for misinterpretation of his proof (as he himself did earlier) for this particular case has some interesting implications. He did not make the distinction between radiation from a bound electron driven by an external alternating field and one falling in a nuclear potential. Similar failures lead to misinterpreting the differences between virtual and real photons.

  2. A quantum photonic dissipative transport theory

    NASA Astrophysics Data System (ADS)

    Lei, Chan U.; Zhang, Wei-Min

    2012-05-01

    In this paper, a quantum transport theory for describing photonic dissipative transport dynamics in nanophotonics is developed. The nanophotonic devices concerned in this paper consist of on-chip all-optical integrated circuits incorporating photonic bandgap waveguides and driven resonators embedded in nanostructured photonic crystals. The photonic transport through waveguides is entirely determined from the exact master equation of the driven resonators, which is obtained by explicitly eliminating all the degrees of freedom of the waveguides (treated as reservoirs). Back-reactions from the reservoirs are fully taken into account. The relation between the driven photonic dynamics and photocurrents is obtained explicitly. The non-Markovian memory structure and quantum decoherence dynamics in photonic transport can then be fully addressed. As an illustration, the theory is utilized to study the transport dynamics of a photonic transistor consisting of a nanocavity coupled to two waveguides in photonic crystals. The controllability of photonic transport through the external driven field is demonstrated.

  3. Single-fraction high-dose-rate brachytherapy using real-time transrectal ultrasound based planning in combination with external beam radiotherapy for prostate cancer: dosimetrics and early clinical results

    PubMed Central

    Lauche, Olivier; Delouya, Guila; Taussky, Daniel; Menard, Cynthia; Béliveau-Nadeau, Dominic; Hervieux, Yannick; Larouche, Renée

    2016-01-01

    Purpose To validate the feasibility of a single-fraction high-dose-rate brachytherapy (HDRBT) boost for prostate cancer using real-time transrectal ultrasound (TRUS) based planning. Material and methods From August 2012 to September 2015, 126 patients underwent a single-fraction HDRBT boost of 15 Gy using real-time TRUS based planning. External beam radiation therapy (EBRT) (37.5 Gy/15 fractions, 44 Gy/22 fractions, or 45 Gy/25 fractions) was performed before (31%) or after (69%) HDRBT boost. Genito-urinary (GU) and gastro-intestinal (GI) toxicity were assessed 4 and 12 months after the end of combined treatment using the international prostate symptom score scale (IPSS) and the common terminology criteria for adverse events (CTCAE) v3.0. Results All dose-planning objectives were achieved in 90% of patients. Prostate D90 ≥ 105% and ≤ 115% was achieved in 99% of patients, prostate V150 ≤ 40% in 99%, prostate V200 < 11% in 96%, urethra D10 < 120% for 99%, urethra V125 = 0% in 100%, and rectal V75 < 1 cc in 93% of patients. Median IPSS score was 4 at baseline and did not change at 4 and 12 months after combined treatment. No patients developed ≥ grade 2 GI toxicity. With a median follow-up of 10 months, only two patients experienced biochemical failure. Among patients who didn't receive ADT, cumulative percentage of patients with PSA ≤ 1 ng/ml at 4 and 18 months was respectively 23% and 66%. Conclusions Single-fraction HDRBT boost of 15 Gy using real-time TRUS based planning achieves consistently high dosimetry quality. In combination with EBRT, toxicity outcomes appear promising. A longer follow-up is needed to assess long-term outcome and toxicities.

  4. Proton radiotherapy dose perturbations caused by esophageal stents of varying material composition are negligible in an experimental model

    PubMed Central

    Jalaj, Sujai; Lee, Sang Yeob; McGaw, Camille; John, Bijo K; Li, Zuofeng; Awad, Ziad T; Scolapio, James S; Munoz, Juan C

    2015-01-01

    Background: Self-expanding metal and plastic esophageal stents (SEMS and SEPS, respectively) are used in conjunction with chemoradiation for palliation of malignant dysphagia. To date, the dosimetric effects of stents undergoing proton radiotherapy are not known. Study aim: To investigate the proton radiotherapy dose perturbations caused by esophageal stents of varying designs and materials undergoing external beam treatment for esophageal cancer. Patients and methods: Simulated clinical protocol. Solid acrylic phantom was used to mimic the esophageal tissue environment. Stents made of nitinol, stainless steel and polyester were tested. Proton beam dose of 2 Gy-E was delivered to each stent in a single anterior to posterior field. Film and image based evidence of dose perturbation were main outcomes measured. Results: Only the stainless steel and plastic stents demonstrated slight overall dose attenuations (– 0.5 % and – 0.4 %, respectively). All the nitinol-based stents demonstrated minimal overall dose perturbations ranging from 0.0 % to 1.2 %. Negligible dose perturbations were observed on each of the stent surfaces proximal to the radiation source, ranging from – 0.8 % (stainless steel stent) to 1.0 % (nitinol stent). Negligible dose effects were also observed on the distal surfaces of each stent ranging from – 0.5 % (plastic and stainless steel stents) to 1.0 % (nitinol stent). Conclusion: Proton radiotherapy dose perturbations caused by stents of varying designs and material composition are negligible. Negligible dose perturbation is in keeping with the inherent advantage of proton therapy over traditional radiotherapy composed of photons – given its relative large mass, protons have little side scatter. PMID:26134771

  5. Dose Escalation Improves Cancer-Related Events at 10 Years for Intermediate- and High-Risk Prostate Cancer Patients Treated With Hypofractionated High-Dose-Rate Boost and External Beam Radiotherapy

    SciTech Connect

    Martinez, Alvaro A.; Gonzalez, Jose; Ye Hong; Ghilezan, Mihai; Shetty, Sugandh; Kernen, Kenneth; Gustafson, Gary; Krauss, Daniel; Vicini, Frank; Kestin, Larry

    2011-02-01

    Purpose: To evaluate the 10-year outcomes of intermediate- and high-risk prostate cancer patients treated with a prospective dose escalation hypofractionated trial of pelvic external beam radiation therapy (P-EBRT) with a high-dose-rate (HDR) brachytherapy boost. Methods and Materials: From 1992 to 2007, 472 patients were treated with a HDR boost at William Beaumont Hospital. They had at least one of the following: a prostate-specific antigen (PSA) level of >10 ng/ml, a Gleason score of {>=}7, or clinical stage {>=}T2b. Patients received 46-Gy P-EBRT and an HDR boost. The HDR dose fractionation was divided into two dose levels. The prostate biologically equivalent dose (BED) low-dose-level group received <268 Gy, and the high-dose group received >268 Gy . Phoenix biochemical failure (BF) definition was used. Results: Median follow-up was 8.2 years (range, 0.4-17 years). The 10-year biochemical failure rate of 43.1% vs. 18.9%, (p < 0.001), the clinical failure rate of 23.4% vs. 7.7%, (p < 0.001), and the distant metastasis of 12.4% vs. 5.7%, (p = 0.028) were all significantly better for the high-dose level group. On Cox multivariate analysis, higher BED levels (p = 0.017; hazard ratio [HR]= 0.586), pretreatment PSA assays (p < 0.001, HR = 1.022), and Gleason scores (p = 0.004) were significant variables for reduced biochemical failure. Higher dose levels (p, 0.002; HR, 0.397) and Gleason scores (p < 0.001) were significant for clinical failure. Grade 3 genitourinary complications were 2% and 3%, respectively, and grade 3 gastrointestinal complication was <0.5%. Conclusions: This prospective trial using P-EBRT with HDR boost and hypofractionated dose escalation demonstrates a strong dose-response relationship for intermediate- and high-risk prostate cancer patients. The improvement at 10 years for locoregional control with higher radiation doses (BED, > 268Gy) has significantly decreased biochemical and clinical failures as well as distant metastasis.

  6. [Radiotherapy of skin cancers].

    PubMed

    Hennequin, C; Rio, E; Mahé, M-A

    2016-09-01

    The indications of radiotherapy for skin cancers are not clearly defined because of the lack of randomised trials or prospective studies. For basal cell carcinomas, radiotherapy frequently offers a good local control, but a randomized trial showed that surgery is more efficient and less toxic. Indications of radiotherapy are contra-indications of surgery for patients older than 60, non-sclerodermiform histology and occurring in non-sensitive areas. Adjuvant radiotherapy could be proposed to squamous cell carcinomas, in case of poor prognostic factors. Dose of 60 to 70Gy are usually required, and must be modulated to the size of the lesions. Adjuvant radiotherapy seems beneficial for desmoplastic melanomas but not for the other histological types. Prophylactic nodal irradiation (45 to 50Gy), for locally advanced tumours (massive nodal involvement), decreases the locoregional failure rate but do not increase survival. Adjuvant radiotherapy (50 to 56Gy) for Merckel cell carcinomas increases also the local control rate, as demonstrated by meta-analysis and a large epidemiological study. Nodal areas must be included, if there is no surgical exploration (sentinel lymph node dissection). Kaposi sarcomas are radiosensitive and could be treated with relatively low doses (24 to 30Gy). Also, cutaneous lymphomas are good indications for radiotherapy: B lymphomas are electively treated with limited fields. The role of total skin electron therapy for T-lymphomas is still discussed; but palliative radiotherapy is very efficient in case of cutaneous nodules. PMID:27522189

  7. Planning National Radiotherapy Services

    PubMed Central

    Rosenblatt, Eduardo

    2014-01-01

    Countries, states, and island nations often need forward planning of their radiotherapy services driven by different motives. Countries without radiotherapy services sponsor patients to receive radiotherapy abroad. They often engage professionals for a feasibility study in order to establish whether it would be more cost-beneficial to establish a radiotherapy facility. Countries where radiotherapy services have developed without any central planning, find themselves in situations where many of the available centers are private and thus inaccessible for a majority of patients with limited resources. Government may decide to plan ahead when a significant exodus of cancer patients travel to another country for treatment, thus exposing the failure of the country to provide this medical service for its citizens. In developed countries, the trigger has been the existence of highly visible waiting lists for radiotherapy revealing a shortage of radiotherapy equipment. This paper suggests that there should be a systematic and comprehensive process of long-term planning of radiotherapy services at the national level, taking into account the regulatory infrastructure for radiation protection, planning of centers, equipment, staff, education programs, quality assurance, and sustainability aspects. Realistic budgetary and cost considerations must also be part of the project proposal or business plan. PMID:25505730

  8. 3.4 Radiotherapy

    NASA Astrophysics Data System (ADS)

    Kramer, H.-M.; Selbach, H.-J.; Vatnitsky, S.

    This document is part of Subvolume A 'Fundamentals and Data in Radiobiology, Radiation Biophysics, Dosimetry and Medical Radiological Protection' of Volume 7 'Medical Radiological Physics' of Landolt-Börnstein - Group VIII 'Advanced Materials and Technologies'. It contains the Section '3.4 Radiotherapy' of the Chapter '3 Dosimetry in Diagnostic Radiology and Radiotherapy' with the contents:

  9. Radiotherapy for ocular tumours.

    PubMed

    Stannard, C; Sauerwein, W; Maree, G; Lecuona, K

    2013-02-01

    Ocular tumours present a therapeutic challenge because of the sensitive tissues involved and the necessity to destroy the tumour while minimising visual loss. Radiotherapy (RT) is one of several modalites used apart from surgery, laser, cryotherapy, and chemotherapy. Both external beam RT (EBRT) and brachytherapy are used. Tumours of the bulbar conjunctiva, squamous carcinoma and malignant melanoma, can be treated with a radioactive plaque: strontium-90, ruthenium-106 (Ru-106), or iodine-125 (I-125), after excision. If the tumour involves the fornix or tarsal conjunctiva, proton therapy can treat the conjunctiva and spare most of the eye. Alternatively, an I-125 interstitial implant can be used with shielding of the cornea and lens. Conjunctival mucosal-associated lymphoid tissue lymphoma can be treated with an anterior electron field with lens shielding and 25-30 Gray (Gy) in 2 Gy fractions. Discrete retinoblastoma (RB), too large for cryotherapy or thermolaser, or recurrent after these modalities, can be treated with plaque therapy, I-125, or Ru-106. For large RB, multiple tumours, or vitreous seeds the whole eye can be treated with an I-125 applicator, sparing the bony orbit, or with EBRT, under anaesthetic, using X-rays or proton therapy with vacuum contact lenses to fix the eyes in the required position. Post-enucleated orbits at risk for recurrent RB can be treated with an I-125 implant with shielding to reduce the dose to the bony orbit. Uveal malignant melanomas can be treated with plaque or proton therapy with excellent local control. Preservation of vision will depend on the initial size and location of the tumour. PMID:23174750

  10. Radiotherapy for ocular tumours

    PubMed Central

    Stannard, C; Sauerwein, W; Maree, G; Lecuona, K

    2013-01-01

    Ocular tumours present a therapeutic challenge because of the sensitive tissues involved and the necessity to destroy the tumour while minimising visual loss. Radiotherapy (RT) is one of several modalites used apart from surgery, laser, cryotherapy, and chemotherapy. Both external beam RT (EBRT) and brachytherapy are used. Tumours of the bulbar conjunctiva, squamous carcinoma and malignant melanoma, can be treated with a radioactive plaque: strontium-90, ruthenium-106 (Ru-106), or iodine-125 (I-125), after excision. If the tumour involves the fornix or tarsal conjunctiva, proton therapy can treat the conjunctiva and spare most of the eye. Alternatively, an I-125 interstitial implant can be used with shielding of the cornea and lens. Conjunctival mucosal-associated lymphoid tissue lymphoma can be treated with an anterior electron field with lens shielding and 25–30 Gray (Gy) in 2 Gy fractions. Discrete retinoblastoma (RB), too large for cryotherapy or thermolaser, or recurrent after these modalities, can be treated with plaque therapy, I-125, or Ru-106. For large RB, multiple tumours, or vitreous seeds the whole eye can be treated with an I-125 applicator, sparing the bony orbit, or with EBRT, under anaesthetic, using X-rays or proton therapy with vacuum contact lenses to fix the eyes in the required position. Post-enucleated orbits at risk for recurrent RB can be treated with an I-125 implant with shielding to reduce the dose to the bony orbit. Uveal malignant melanomas can be treated with plaque or proton therapy with excellent local control. Preservation of vision will depend on the initial size and location of the tumour. PMID:23174750

  11. Feasibility of a Multigroup Deterministic Solution Method for 3D Radiotherapy Dose Calculations

    PubMed Central

    Vassiliev, Oleg N.; Wareing, Todd A.; Davis, Ian M.; McGhee, John; Barnett, Douglas; Horton, John L.; Gifford, Kent; Failla, Gregory; Titt, Uwe; Mourtada, Firas

    2008-01-01

    Purpose To investigate the potential of a novel deterministic solver, Attila, for external photon beam radiotherapy dose calculations. Methods and Materials Two hypothetical cases for prostate and head and neck cancer photon beam treatment plans were calculated using Attila and EGSnrc Monte Carlo simulations. Open beams were modeled as isotropic photon point sources collimated to specified field sizes (100 cm SSD). The sources had a realistic energy spectrum calculated by Monte Carlo for a Varian Clinac 2100 operated in a 6MV photon mode. The Attila computational grids consisted of 106,000 elements, or 424,000 spatial degrees of freedom, for the prostate case, and 123,000 tetrahedral elements, or 492,000 spatial degrees of freedom, for the head and neck cases. Results For both cases, results demonstrate excellent agreement between Attila and EGSnrc in all areas, including the build-up regions, near heterogeneities, and at the beam penumbra. Dose agreement for 99% of the voxels was within 3% (relative point-wise difference) or 3mm distance-to-agreement criterion. Localized differences between the Attila and EGSnrc results were observed at bone and soft tissue interfaces, and are attributable to the effect of voxel material homogenization in calculating dose-to-medium in EGSnrc. For both cases, Attila calculation times were under 20 CPU minutes on a single 2.2 GHz AMD Opteron processor. Conclusions The methods in Attila have the potential to be the basis for an efficient dose engine for patient specific treatment planning, providing accuracy similar to that obtained by Monte Carlo. PMID:18722273

  12. Feasibility of a Multigroup Deterministic Solution Method for Three-Dimensional Radiotherapy Dose Calculations

    SciTech Connect

    Vassiliev, Oleg N.; Wareing, Todd A.; Davis, Ian M; McGhee, John; Barnett, Douglas; Horton, John L.; Gifford, Kent; Failla, Gregory; Titt, Uwe; Mourtada, Firas

    2008-09-01

    Purpose: To investigate the potential of a novel deterministic solver, Attila, for external photon beam radiotherapy dose calculations. Methods and Materials: Two hypothetical cases for prostate and head-and-neck cancer photon beam treatment plans were calculated using Attila and EGSnrc Monte Carlo simulations. Open beams were modeled as isotropic photon point sources collimated to specified field sizes. The sources had a realistic energy spectrum calculated by Monte Carlo for a Varian Clinac 2100 operated in a 6-MV photon mode. The Attila computational grids consisted of 106,000 elements, or 424,000 spatial degrees of freedom, for the prostate case, and 123,000 tetrahedral elements, or 492,000 spatial degrees of freedom, for the head-and-neck cases. Results: For both cases, results demonstrate excellent agreement between Attila and EGSnrc in all areas, including the build-up regions, near heterogeneities, and at the beam penumbra. Dose agreement for 99% of the voxels was within the 3% (relative point-wise difference) or 3-mm distance-to-agreement criterion. Localized differences between the Attila and EGSnrc results were observed at bone and soft-tissue interfaces and are attributable to the effect of voxel material homogenization in calculating dose-to-medium in EGSnrc. For both cases, Attila calculation times were <20 central processing unit minutes on a single 2.2-GHz AMD Opteron processor. Conclusions: The methods in Attila have the potential to be the basis for an efficient dose engine for patient-specific treatment planning, providing accuracy similar to that obtained by Monte Carlo.

  13. External inverse-Compton Emission from Blazar Jets

    SciTech Connect

    Carson, Jennifer E.; Chiang, James; /SLAC

    2007-09-25

    According to leptonic models for the high-energy emission from blazars, relativistic electrons in the inner jets inverse-Compton scatter photons from a variety of sources. Seed photons are certainly introduced via the synchrotron process from the electrons themselves, but external sources of seed photons may also be present. In this paper, we present detailed derivations of the equations describing external inverse-Compton scattering from two sources of seed photons: direct emission from the accretion disk, and accretion disk photons that have scattered off the broad line region. For each source, we derive the seed photon spectrum incident on the jet, the single electron energy loss rate, and the emitted photon spectrum.

  14. Contribution of FDOPA PET to radiotherapy planning for advanced glioma

    NASA Astrophysics Data System (ADS)

    Dowson, Nicholas; Fay, Michael; Thomas, Paul; Jeffree, Rosalind; McDowall, Robert; Winter, Craig; Coulthard, Alan; Smith, Jye; Gal, Yaniv; Bourgeat, Pierrick; Salvado, Olivier; Crozier, Stuart; Rose, Stephen

    2014-03-01

    Despite radical treatment with surgery, radiotherapy and chemotherapy, advanced gliomas recur within months. Geographic misses in radiotherapy planning may play a role in this seemingly ineluctable recurrence. Planning is typically performed on post-contrast MRIs, which are known to underreport tumour volume relative to FDOPA PET scans. FDOPA PET fused with contrast enhanced MRI has demonstrated greater sensitivity and specificity than MRI alone. One sign of potential misses would be differences between gross target volumes (GTVs) defined using MRI alone and when fused with PET. This work examined whether such a discrepancy may occur. Materials and Methods: For six patients, a 75 minute PET scan using 3,4-dihydroxy-6-18F-fluoro-L-phynel-alanine (18F-FDOPA) was taken within 2 days of gadolinium enhanced MRI scans. In addition to standard radiotherapy planning by an experienced radiotherapy oncologist, a second gross target volume (GTV) was defined by an experienced nuclear medicine specialist for fused PET and MRI, while blinded to the radiotherapy plans. The volumes from standard radiotherapy planning were compared to the PET defined GTV. Results: The comparison indicated radiotherapy planning would change in several cases if FDOPA PET data was available. PET-defined contours were external to 95% prescribed dose for several patients. However, due to the radiotherapy margins, the discrepancies were relatively small in size and all received a dose of 50 Gray or more. Conclusions: Given the limited size of the discrepancies it is uncertain that geographic misses played a major role in patient outcome. Even so, the existence of discrepancies indicates that FDOPA PET could assist in better defining margins when planning radiotherapy for advanced glioma, which could be important for highly conformal radiotherapy plans.

  15. External Beam Therapy (EBT)

    MedlinePlus

    ... Physician Resources Professions Site Index A-Z External Beam Therapy (EBT) External beam therapy (EBT) is a ... follow-up should I expect? What is external beam therapy and how is it used? External beam ...

  16. Collimator-free photon tomography

    DOEpatents

    Dilmanian, F.A.; Barbour, R.L.

    1998-10-06

    A method of uncollimated single photon emission computed tomography includes administering a radioisotope to a patient for producing gamma ray photons from a source inside the patient. Emissivity of the photons is measured externally of the patient with an uncollimated gamma camera at a plurality of measurement positions surrounding the patient for obtaining corresponding energy spectrums thereat. Photon emissivity at the plurality of measurement positions is predicted using an initial prediction of an image of the source. The predicted and measured photon emissivities are compared to obtain differences therebetween. Prediction and comparison is iterated by updating the image prediction until the differences are below a threshold for obtaining a final prediction of the source image. 6 figs.

  17. Collimator-free photon tomography

    DOEpatents

    Dilmanian, F. Avraham; Barbour, Randall L.

    1998-10-06

    A method of uncollimated single photon emission computed tomography includes administering a radioisotope to a patient for producing gamma ray photons from a source inside the patient. Emissivity of the photons is measured externally of the patient with an uncollimated gamma camera at a plurality of measurement positions surrounding the patient for obtaining corresponding energy spectrums thereat. Photon emissivity at the plurality of measurement positions is predicted using an initial prediction of an image of the source. The predicted and measured photon emissivities are compared to obtain differences therebetween. Prediction and comparison is iterated by updating the image prediction until the differences are below a threshold for obtaining a final prediction of the source image.

  18. Photon absorptiometry

    SciTech Connect

    Velchik, M.G.

    1987-01-01

    Recently, there has been a renewed interest in the detection and treatment of osteoporosis. This paper is a review of the merits and limitations of the various noninvasive modalities currently available for the measurement of bone mineral density with special emphasis placed upon the nuclear medicine techniques of single-photon and dual-photon absorptiometry. The clinicians should come away with an understanding of the relative advantages and disadvantages of photon absorptiometry and its optimal clinical application. 49 references.

  19. Potential hazard due to induced radioactivity secondary to radiotherapy: the report of task group 136 of the American Association of Physicists in Medicine.

    PubMed

    Thomadsen, Bruce; Nath, Ravinder; Bateman, Fred B; Farr, Jonathan; Glisson, Cal; Islam, Mohammad K; LaFrance, Terry; Moore, Mary E; George Xu, X; Yudelev, Mark

    2014-11-01

    External-beam radiation therapy mostly uses high-energy photons (x-rays) produced by medical accelerators, but many facilities now use proton beams, and a few use fast-neutron beams. High-energy photons offer several advantages over lower-energy photons in terms of better dose distributions for deep-seated tumors, lower skin dose, less sensitivity to tissue heterogeneities, etc. However, for beams operating at or above 10 MV, some of the materials in the accelerator room and the radiotherapy patient become radioactive due primarily to photonuclear reactions and neutron capture, exposing therapy staff and patients to unwanted radiation dose. Some recent advances in radiotherapy technology require treatments using a higher number of monitor units and monitor-unit rates for the same delivered dose, and compared to the conventional treatment techniques and fractionation schemes, the activation dose to personnel can be substantially higher. Radiotherapy treatments with proton and neutron beams all result in activated materials in the treatment room. In this report, the authors review critically the published literature on radiation exposures from induced radioactivity in radiotherapy. They conclude that the additional exposure to the patient due to induced radioactivity is negligible compared to the overall radiation exposure as a part of the treatment. The additional exposure to the staff due to induced activity from photon beams is small at an estimated level of about 1 to 2 mSv y. This is well below the allowed occupational exposure limits. Therefore, the potential hazard to staff from induced radioactivity in the use of high-energy x-rays is considered to be low, and no specific actions are considered necessary or mandatory. However, in the spirit of the "As Low as Reasonably Achievable (ALARA)" program, some reasonable steps are recommended that can be taken to reduce this small exposure to an even lower level. The dose reduction strategies suggested should be

  20. Technical considerations in brachytherapy boost for a case of squamous cell carcinoma of the external auditory canal based on our case.

    PubMed

    Ilangovan, Bhargavi; Stumpf, Janos; Murali, V; Sasikumar, Neetu; Devi, Rathna

    2015-01-01

    Squamous cell carcinoma of the external auditory canal is a rare entity. The patients present with ear discharge and otalgia. They are treated with radiotherapy and surgery. Surgery with oncological priorities is quite complex with substantial consequences. We are reporting a patient with squamous cell carcinoma of the external auditory canal, who was treated with limited surgery followed by radiotherapy. Radiotherapy was a combination of external beam radiotherapy and brachytherapy. High dose rate brachytherapy was given using an ear speculum fixed with wax and a suction catheter. This article is to highlight the technique and dosimetry of the brachytherapy procedure. PMID:26458716

  1. MO-A-BRD-07: Feasibility of X-Ray Acoustic Computed Tomography as a Tool for Calibration and In Vivo Dosimetry of Radiotherapy Electron and Photon Beams

    SciTech Connect

    Hickling, S; Hobson, M; El Naqa, I

    2014-06-15

    Purpose: This work simulates radiation-induced acoustic waves to assess the feasibility of x-ray acoustic computed tomography (XACT) as a dosimeter. XACT exploits the phenomenon that acoustic waves with amplitude proportional to the dose deposited are induced following a radiation pulse. After detecting these acoustic waves with an ultrasound transducer, an image of the dose distribution can be reconstructed in realtime. Methods: Monte Carlo was used to simulate the dose distribution for monoenergetic 6 MeV photon and 9 MeV electron beams incident on a water tank. The dose distribution for a prostate patient planned with a photon 4-field box technique was calculated using clinical treatment planning software. All three dose distributions were converted into initial pressure distributions, and transportation of the induced acoustic waves was simulated using an open-source toolkit. Ideal transducers were placed around the circumference of the target to detect the acoustic waves, and a time reversal reconstruction algorithm was used to obtain an XACT image of the dose for each radiation pulse. Results: For the photon water tank relative dosimetry case, it was found that the normalized acoustic signal amplitude agreed with the normalized dose at depths from 0 cm to 10 cm, with an average percent difference of 0.5%. For the reconstructed in-plane dose distribution of an electron water tank irradiation, all pixels passed a 3%–3 mm 2D gamma test. The reconstructed prostate dose distribution closely resembled the plan, with 89% of pixels passing a 3%–3 mm 2D gamma test. For all situations, the amplitude of the induced acoustic waves ranged from 0.01 Pa to 1 Pa. Conclusion: Based on the amplitude of the radiation-induced acoustic waves and accuracy of the reconstructed dose distributions, XACT is a feasible technique for dosimetry in both calibration and in vivo environments for photon and electron beams and merits further investigation. Funding from NSERC, CIHR and Mc

  2. Measurement of neutron ambient dose equivalent in passive carbon-ion and proton radiotherapies

    SciTech Connect

    Yonai, Shunsuke; Matsufuji, Naruhiro; Kanai, Tatsuaki; Matsui, Yuki; Matsushita, Kaoru; Yamashita, Haruo; Numano, Masumi; Sakae, Takeji; Terunuma, Toshiyuki; Nishio, Teiji; Kohno, Ryosuke; Akagi, Takashi

    2008-11-15

    Secondary neutron ambient dose equivalents per the treatment absorbed dose in passive carbon-ion and proton radiotherapies were measured using a rem meter, WENDI-II at two carbon-ion radiotherapy facilities and four proton radiotherapy facilities in Japan. Our measured results showed that (1) neutron ambient dose equivalent in carbon-ion radiotherapy is lower than that in proton radiotherapy, and (2) the difference to the measured neutron ambient dose equivalents among the facilities is within a factor of 3 depending on the operational beam setting used at the facility and the arrangement of the beam line, regardless of the method for making a laterally uniform irradiation field: the double scattering method or the single-ring wobbling method. The reoptimization of the beam line in passive particle radiotherapy is an effective way to reduce the risk of secondary cancer because installing an adjustable precollimator and designing the beam line devices with consideration of their material, thickness and location, etc., can significantly reduce the neutron exposure. It was also found that the neutron ambient dose equivalent in passive particle radiotherapy is equal to or less than that in the photon radiotherapy. This result means that not only scanning particle radiotherapy but also passive particle radiotherapy can provide reduced exposure to normal tissues around the target volume without an accompanied increase in total body dose.

  3. Achieving nonreciprocal unidirectional single-photon quantum transport using the photonic Aharonov-Bohm effect.

    PubMed

    Yuan, Luqi; Xu, Shanshan; Fan, Shanhui

    2015-11-15

    We show that nonreciprocal unidirectional single-photon quantum transport can be achieved with the photonic Aharonov-Bohm effect. The system consists of a 1D waveguide coupling to two three-level atoms of the V-type. The two atoms, in addition, are each driven by an external coherent field. We show that the phase of the external coherent field provides a gauge potential for the photon states. With a proper choice of the phase difference between the two coherent fields, the transport of a single photon can exhibit unity contrast in its transmissions for the two propagation directions. PMID:26565819

  4. Monte Carlo treatment planning with modulated electron radiotherapy: framework development and application

    NASA Astrophysics Data System (ADS)

    Alexander, Andrew William

    Within the field of medical physics, Monte Carlo radiation transport simulations are considered to be the most accurate method for the determination of dose distributions in patients. The McGill Monte Carlo treatment planning system (MMCTP), provides a flexible software environment to integrate Monte Carlo simulations with current and new treatment modalities. A developing treatment modality called energy and intensity modulated electron radiotherapy (MERT) is a promising modality, which has the fundamental capabilities to enhance the dosimetry of superficial targets. An objective of this work is to advance the research and development of MERT with the end goal of clinical use. To this end, we present the MMCTP system with an integrated toolkit for MERT planning and delivery of MERT fields. Delivery is achieved using an automated "few leaf electron collimator" (FLEC) and a controller. Aside from the MERT planning toolkit, the MMCTP system required numerous add-ons to perform the complex task of large-scale autonomous Monte Carlo simulations. The first was a DICOM import filter, followed by the implementation of DOSXYZnrc as a dose calculation engine and by logic methods for submitting and updating the status of Monte Carlo simulations. Within this work we validated the MMCTP system with a head and neck Monte Carlo recalculation study performed by a medical dosimetrist. The impact of MMCTP lies in the fact that it allows for systematic and platform independent large-scale Monte Carlo dose calculations for different treatment sites and treatment modalities. In addition to the MERT planning tools, various optimization algorithms were created external to MMCTP. The algorithms produced MERT treatment plans based on dose volume constraints that employ Monte Carlo pre-generated patient-specific kernels. The Monte Carlo kernels are generated from patient-specific Monte Carlo dose distributions within MMCTP. The structure of the MERT planning toolkit software and

  5. Recruitment in Radiotherapy

    ERIC Educational Resources Information Center

    Deeley, T. J.; And Others

    1976-01-01

    The Faculty Board of Radiotherapy and Oncology of the Royal College of Radiobiologists surveyed the factors thought to influence recruitment into the specialty. Possible factors listed in replies of 36 questionnaires are offered. (LBH)

  6. Real-time in vivo Cherenkoscopy imaging during external beam radiation therapy

    PubMed Central

    Gladstone, David J.; Jarvis, Lesley A.; Strawbridge, Rendall R.; Jack Hoopes, P.; Friedman, Oscar D.; Glaser, Adam K.

    2013-01-01

    Abstract. Cherenkov radiation is induced when charged particles travel through dielectric media (such as biological tissue) faster than the speed of light through that medium. Detection of this radiation or excited luminescence during megavoltage external beam radiotherapy (EBRT) can allow emergence of a new approach to superficial dose estimation, functional imaging, and quality assurance for radiation therapy dosimetry. In this letter, the first in vivo Cherenkov images of a real-time Cherenkoscopy during EBRT are presented. The imaging system consisted of a time-gated intensified charge coupled device (ICCD) coupled with a commercial lens. The ICCD was synchronized to the linear accelerator to detect Cherenkov photons only during the 3.25-μs radiation bursts. Images of a tissue phantom under irradiation show that the intensity of Cherenkov emission is directly proportional to radiation dose, and images can be acquired at 4.7  frames/s with SNR>30. Cherenkoscopy was obtained from the superficial regions of a canine oral tumor during planned, Institutional Animal Care and Use Committee approved, conventional (therapeutically appropriate) EBRT irradiation. Coregistration between photography and Cherenkoscopy validated that Cherenkov photons were detected from the planned treatment region. Real-time images correctly monitored the beam field changes corresponding to the planned dynamic wedge movement, with accurate extent of overall beam field, and expected cold and hot regions. PMID:24247743

  7. Photon Colliders

    SciTech Connect

    Gronberg, J

    2002-10-07

    A photon collider interaction region has the possibility of expanding the physics reach of a future TeV scale electron-positron collider. A survey of ongoing efforts to design the required lasers and optics to create a photon collider is presented in this paper.

  8. [Management of soft tissues sarcoma of the limbs by external beam radiation therapy].

    PubMed

    Moureau-Zabotto, L; Delannes, M; Le Péchoux, C; Sunyach, M P; Kantor, G; Sargos, P; Thariat, J; Llacer-Moscardo, C

    2016-04-01

    Soft tissue sarcomas are rare tumours. Conservative surgery followed by postoperative radiation therapy represents the gold standard in the majority of cases. Postoperative radiotherapy improves local control without affecting survival. Besides the quality of surgical excision, which remains the major prognostic factor, the importance of the irradiation volume and particularly margins used in external beam radiotherapy were also found to influence local control of the disease. In this study, we propose to conduct a literature review on the present state of our knowledge on this subject in the form of an articulated controversy: in favour or opposed to large margins in external radiotherapy. PMID:26995071

  9. Self-assembled tunable photonic hyper-crystals

    NASA Astrophysics Data System (ADS)

    Smolyaninov, Igor; Smolyaninova, Vera; Yost, Bradley; Lahneman, David; Gresock, Thomas; Narimanov, Evgenii

    2015-03-01

    We demonstrate a novel artificial optical material, the photonic hyper-crystal, which combines the most interesting features of hyperbolic metamaterials and photonic crystals. Similar to hyperbolic metamaterials, photonic hyper-crystals exhibit broadband divergence in their photonic density of states due to the lack of usual diffraction limit on the photon wave vector. On the other hand, similar to photonic crystals, hyperbolic dispersion law of extraordinary photons is modulated by forbidden gaps near the boundaries of photonic Brillouin zones. Three dimensional self-assembly of photonic hyper-crystals has been achieved by application of external magnetic field to a cobalt nanoparticle-based ferrofluid. Unique spectral properties of photonic hyper-crystals lead to extreme sensitivity of the material to monolayer coatings of cobalt nanoparticles, which should find numerous applications in biological and chemical sensing. This work was supported in part by NSF Grant DMR-1104676, NSF Center for Photonic and Multiscale Nanomaterials, ARO MURI and Gordon and Berry Moore Foundation.

  10. Gamma Cherenkov-transition radiation of high energy electrons and methods for the measurement of the refractive index of MeV photons using total internal and external reflections (Invited talk)

    NASA Astrophysics Data System (ADS)

    Ispirian, K. A.

    2014-05-01

    It is given a review of the theoretical works showing that gamma ray Cherenkov-transition radiation (GCTR) is produced in some materials the refractive index of which in gamma region is greater than 1 according to the famous results of [1]. Since there are some published doubts [2] on the theoretical results of [1], and taking into account the difficulties of the experiment [1], in order to confirm or decline the results [1] it is proposed to study experimentally GCTR and an experimental method for the measurement of refractive index of MeV photons.

  11. Monitoring external beam radiotherapy using real-time beam visualization

    SciTech Connect

    Jenkins, Cesare H.; Naczynski, Dominik J.; Yu, Shu-Jung S.; Xing, Lei

    2015-01-15

    Purpose: To characterize the performance of a novel radiation therapy monitoring technique that utilizes a flexible scintillating film, common optical detectors, and image processing algorithms for real-time beam visualization (RT-BV). Methods: Scintillating films were formed by mixing Gd{sub 2}O{sub 2}S:Tb (GOS) with silicone and casting the mixture at room temperature. The films were placed in the path of therapeutic beams generated by medical linear accelerators (LINAC). The emitted light was subsequently captured using a CMOS digital camera. Image processing algorithms were used to extract the intensity, shape, and location of the radiation field at various beam energies, dose rates, and collimator locations. The measurement results were compared with known collimator settings to validate the performance of the imaging system. Results: The RT-BV system achieved a sufficient contrast-to-noise ratio to enable real-time monitoring of the LINAC beam at 20 fps with normal ambient lighting in the LINAC room. The RT-BV system successfully identified collimator movements with sub-millimeter resolution. Conclusions: The RT-BV system is capable of localizing radiation therapy beams with sub-millimeter precision and tracking beam movement at video-rate exposure.

  12. (Radio)Biological Optimization of External-Beam Radiotherapy

    PubMed Central

    Nahum, Alan E.; Uzan, Julien

    2012-01-01

    “Biological optimization” (BIOP) means planning treatments using (radio)biological criteria and models, that is, tumour control probability and normal-tissue complication probability. Four different levels of BIOP are identified: Level I is “isotoxic” individualization of prescription dose Dpresc at fixed fraction number. Dpresc is varied to keep the NTCP of the organ at risk constant. Significant improvements in local control are expected for non-small-cell lung tumours. Level II involves the determination of an individualized isotoxic combination of Dpresc and fractionation scheme. This approach is appropriate for “parallel” OARs (lung, parotids). Examples are given using our BioSuite software. Hypofractionated SABR for early-stage NSCLC is effectively Level-II BIOP. Level-III BIOP uses radiobiological functions as part of the inverse planning of IMRT, for example, maximizing TCP whilst not exceeding a given NTCP. This results in non-uniform target doses. The NTCP model parameters (reflecting tissue “architecture”) drive the optimizer to emphasize different regions of the DVH, for example, penalising high doses for quasi-serial OARs such as rectum. Level-IV BIOP adds functional imaging information, for example, hypoxia or clonogen location, to Level III; examples are given of our prostate “dose painting” protocol, BioProp. The limitations of and uncertainties inherent in the radiobiological models are emphasized. PMID:23251227

  13. A quality audit program for external beam radiotherapy

    SciTech Connect

    Hanson, W.F.; Stovall, M.

    1993-12-31

    For more than 25 years, the University of Texas M. D. Anderson Cancer Center has had a quality audit program using mailed dosimeters to verify radiation therapy machine output. Two programs, one compulsory and one voluntary, presently monitor therapy beams at more than 1000 megavoltage-therapy facilities. A successful program requires two major components: a high-precision thermoluminescent dosimeter (TLD) system and dedicated staff that interact closely with the users to resolve discrepancies. The TLD system, the logistics used, and the human interaction of these programs are described. Examples show that the programs can identify major discrepancies, exceeding 5 %, as well as discrepancies as small as 3%.

  14. Means of Intensity Modulation of Radiation in External Radiotherapy

    NASA Astrophysics Data System (ADS)

    Bajusová, Alica; Králik, Gabriel; Miglierini, Marcel

    2010-01-01

    The paper deals with the main means of the beam intensity modifications that are used in radio therapeutic praxis. Physical principles and the main characteristics of the physical wedges and the enhanced dynamic wedges (EDW) are described. The main advantages and the disadvantages of the EDW over the conventional physical wedges are listed. The paper describes also a process of dosimetry verification of the application of the EDW that was applied on The Saint Elizabeth Cancer Institute in Bratislava and it details the experiment of the verification of an isodose distribution within this implementation of the EDW.

  15. Means of Intensity Modulation of Radiation in External Radiotherapy

    SciTech Connect

    Bajusova, Alica; Kralik, Gabriel; Miglierini, Marcel

    2010-01-05

    The paper deals with the main means of the beam intensity modifications that are used in radio therapeutic praxis. Physical principles and the main characteristics of the physical wedges and the enhanced dynamic wedges (EDW) are described. The main advantages and the disadvantages of the EDW over the conventional physical wedges are listed. The paper describes also a process of dosimetry verification of the application of the EDW that was applied on The Saint Elizabeth Cancer Institute in Bratislava and it details the experiment of the verification of an isodose distribution within this implementation of the EDW.

  16. Monitoring external beam radiotherapy using real-time beam visualization

    PubMed Central

    Jenkins, Cesare H.; Naczynski, Dominik J.; Yu, Shu-Jung S.; Xing, Lei

    2015-01-01

    Purpose: To characterize the performance of a novel radiation therapy monitoring technique that utilizes a flexible scintillating film, common optical detectors, and image processing algorithms for real-time beam visualization (RT-BV). Methods: Scintillating films were formed by mixing Gd2O2S:Tb (GOS) with silicone and casting the mixture at room temperature. The films were placed in the path of therapeutic beams generated by medical linear accelerators (LINAC). The emitted light was subsequently captured using a CMOS digital camera. Image processing algorithms were used to extract the intensity, shape, and location of the radiation field at various beam energies, dose rates, and collimator locations. The measurement results were compared with known collimator settings to validate the performance of the imaging system. Results: The RT-BV system achieved a sufficient contrast-to-noise ratio to enable real-time monitoring of the LINAC beam at 20 fps with normal ambient lighting in the LINAC room. The RT-BV system successfully identified collimator movements with sub-millimeter resolution. Conclusions: The RT-BV system is capable of localizing radiation therapy beams with sub-millimeter precision and tracking beam movement at video-rate exposure. PMID:25563243

  17. Photon collider at TESLA

    NASA Astrophysics Data System (ADS)

    Telnov, Valery

    2001-10-01

    High energy photon colliders ( γγ, γe) based on backward Compton scattering of laser light is a very natural addition to e +e - linear colliders. In this report, we consider this option for the TESLA project. Recent study has shown that the horizontal emittance in the TESLA damping ring can be further decreased by a factor of four. In this case, the γγ luminosity in the high energy part of spectrum can reach about (1/3) Le +e -. Typical cross-sections of interesting processes in γγ collisions are higher than those in e +e - collisions by about one order of magnitude, so the number of events in γγ collisions will be more than that in e +e - collisions. Photon colliders can, certainly, give additional information and they are the best for the study of many phenomena. The main question is now the technical feasibility. The key new element in photon colliders is a very powerful laser system. An external optical cavity is a promising approach for the TESLA project. A free electron laser is another option. However, a more straightforward solution is "an optical storage ring (optical trap)" with a diode pumped solid state laser injector which is today technically feasible. This paper briefly reviews the status of a photon collider based on the linear collider TESLA, its possible parameters and existing problems.

  18. NOTE: MMCTP: a radiotherapy research environment for Monte Carlo and patient-specific treatment planning

    NASA Astrophysics Data System (ADS)

    Alexander, A.; DeBlois, F.; Stroian, G.; Al-Yahya, K.; Heath, E.; Seuntjens, J.

    2007-07-01

    Radiotherapy research lacks a flexible computational research environment for Monte Carlo (MC) and patient-specific treatment planning. The purpose of this study was to develop a flexible software package on low-cost hardware with the aim of integrating new patient-specific treatment planning with MC dose calculations suitable for large-scale prospective and retrospective treatment planning studies. We designed the software package 'McGill Monte Carlo treatment planning' (MMCTP) for the research development of MC and patient-specific treatment planning. The MMCTP design consists of a graphical user interface (GUI), which runs on a simple workstation connected through standard secure-shell protocol to a cluster for lengthy MC calculations. Treatment planning information (e.g., images, structures, beam geometry properties and dose distributions) is converted into a convenient MMCTP local file storage format designated, the McGill RT format. MMCTP features include (a) DICOM_RT, RTOG and CADPlan CART format imports; (b) 2D and 3D visualization views for images, structure contours, and dose distributions; (c) contouring tools; (d) DVH analysis, and dose matrix comparison tools; (e) external beam editing; (f) MC transport calculation from beam source to patient geometry for photon and electron beams. The MC input files, which are prepared from the beam geometry properties and patient information (e.g., images and structure contours), are uploaded and run on a cluster using shell commands controlled from the MMCTP GUI. The visualization, dose matrix operation and DVH tools offer extensive options for plan analysis and comparison between MC plans and plans imported from commercial treatment planning systems. The MMCTP GUI provides a flexible research platform for the development of patient-specific MC treatment planning for photon and electron external beam radiation therapy. The impact of this tool lies in the fact that it allows for systematic, platform

  19. Contemporary Breast Radiotherapy and Cardiac Toxicity.

    PubMed

    Yeboa, Debra Nana; Evans, Suzanne Buckley

    2016-01-01

    Long-term cardiac effects are an important component of survivorship after breast radiotherapy. The pathophysiology of cardiotoxicity, history of breast radiotherapy, current methods of cardiac avoidance, modern outcomes, context of historical outcomes, quantifying cardiac effects, and future directions are reviewed in this article. Radiation-induced oxidative stress induces proinflammatory cytokines and is a process that potentiates late effects of fibrosis and intimal proliferation in endothelial vasculature. Breast radiation therapy has changed substantially in recent decades. Several modern technologies exist to improve cardiac avoidance such as deep inspiration breath hold, gating, accelerated partial breast irradiation, and use of modern 3-dimensional planning. Modern outcomes may vary notably from historical long-term cardiac outcomes given the differences in cardiac dose with modern techniques. Methods of quantifying radiation-related cardiotoxicity that correlate with future cardiac risks are needed with current data exploring techniques such as measuring computed tomography coronary artery calcium score, single-photon emission computed tomography imaging, and biomarkers. Placing historical data, dosimetric correlations, and relative cardiac risk in context are key when weighing the benefits of radiotherapy in breast cancer control and survival. Estimating present day cardiac risk in the modern treatment era includes challenges in length of follow-up and the use of confounding cardiotoxic agents such as evolving systemic chemotherapy and targeted therapies. Future directions in both multidisciplinary management and advancing technology in radiation oncology may provide further improvements in patient risk reduction and breast cancer survivorship. PMID:26617212

  20. Analysis of tunable photonic band structure in an extrinsic plasma photonic crystal

    NASA Astrophysics Data System (ADS)

    King, Tzu-Chyang; Yang, Chih-Chiang; Hsieh, Pei-Hung; Chang, Tsung-Wen; Wu, Chien-Jang

    2015-03-01

    In this work, we theoretically investigate the tunable photonic band structure (PBS) for an extrinsic plasma photonic crystal (PPC). The extrinsic PPC is made of a bulk cold plasma layer which is influenced by an externally periodic static magnetic field. The PBS can be tuned by the variation of the magnitude of externally applied magnetic field. In addition, we also show that the PBS can be changed as a function of the electron density as well as the thickness variation.

  1. Monte Carlo simulations of patient dose perturbations in rotational-type radiotherapy due to a transverse magnetic field: A tomotherapy investigation

    SciTech Connect

    Yang, Y. M.; Geurts, M.; Smilowitz, J. B.; Bednarz, B. P.; Sterpin, E.

    2015-02-15

    Purpose: Several groups are exploring the integration of magnetic resonance (MR) image guidance with radiotherapy to reduce tumor position uncertainty during photon radiotherapy. The therapeutic gain from reducing tumor position uncertainty using intrafraction MR imaging during radiotherapy could be partially offset if the negative effects of magnetic field-induced dose perturbations are not appreciated or accounted for. The authors hypothesize that a more rotationally symmetric modality such as helical tomotherapy will permit a systematic mediation of these dose perturbations. This investigation offers a unique look at the dose perturbations due to homogeneous transverse magnetic field during the delivery of Tomotherapy{sup ®} Treatment System plans under varying degrees of rotational beamlet symmetry. Methods: The authors accurately reproduced treatment plan beamlet and patient configurations using the Monte Carlo code GEANT4. This code has a thoroughly benchmarked electromagnetic particle transport physics package well-suited for the radiotherapy energy regime. The three approved clinical treatment plans for this study were for a prostate, head and neck, and lung treatment. The dose heterogeneity index metric was used to quantify the effect of the dose perturbations to the target volumes. Results: The authors demonstrate the ability to reproduce the clinical dose–volume histograms (DVH) to within 4% dose agreement at each DVH point for the target volumes and most planning structures, and therefore, are able to confidently examine the effects of transverse magnetic fields on the plans. The authors investigated field strengths of 0.35, 0.7, 1, 1.5, and 3 T. Changes to the dose heterogeneity index of 0.1% were seen in the prostate and head and neck case, reflecting negligible dose perturbations to the target volumes, a change from 5.5% to 20.1% was observed with the lung case. Conclusions: This study demonstrated that the effect of external magnetic fields can

  2. Monte Carlo simulations of patient dose perturbations in rotational-type radiotherapy due to a transverse magnetic field: A tomotherapy investigation

    PubMed Central

    Yang, Y. M.; Geurts, M.; Smilowitz, J. B.; Sterpin, E.; Bednarz, B. P.

    2015-01-01

    Purpose: Several groups are exploring the integration of magnetic resonance (MR) image guidance with radiotherapy to reduce tumor position uncertainty during photon radiotherapy. The therapeutic gain from reducing tumor position uncertainty using intrafraction MR imaging during radiotherapy could be partially offset if the negative effects of magnetic field-induced dose perturbations are not appreciated or accounted for. The authors hypothesize that a more rotationally symmetric modality such as helical tomotherapy will permit a systematic mediation of these dose perturbations. This investigation offers a unique look at the dose perturbations due to homogeneous transverse magnetic field during the delivery of Tomotherapy® Treatment System plans under varying degrees of rotational beamlet symmetry. Methods: The authors accurately reproduced treatment plan beamlet and patient configurations using the Monte Carlo code geant4. This code has a thoroughly benchmarked electromagnetic particle transport physics package well-suited for the radiotherapy energy regime. The three approved clinical treatment plans for this study were for a prostate, head and neck, and lung treatment. The dose heterogeneity index metric was used to quantify the effect of the dose perturbations to the target volumes. Results: The authors demonstrate the ability to reproduce the clinical dose–volume histograms (DVH) to within 4% dose agreement at each DVH point for the target volumes and most planning structures, and therefore, are able to confidently examine the effects of transverse magnetic fields on the plans. The authors investigated field strengths of 0.35, 0.7, 1, 1.5, and 3 T. Changes to the dose heterogeneity index of 0.1% were seen in the prostate and head and neck case, reflecting negligible dose perturbations to the target volumes, a change from 5.5% to 20.1% was observed with the lung case. Conclusions: This study demonstrated that the effect of external magnetic fields can be

  3. A scintillating fiber dosimeter for radiotherapy

    NASA Astrophysics Data System (ADS)

    Bartesaghi, G.; Conti, V.; Bolognini, D.; Grigioni, S.; Mascagna, V.; Prest, M.; Scazzi, S.; Mozzanica, A.; Cappelletti, P.; Frigerio, M.; Gelosa, S.; Monti, A.; Ostinelli, A.; Giannini, G.; Vallazza, E.

    2007-10-01

    Radiotherapy, together with chemotherapy and surgery, is one of the main methods applied in the fight against cancer; in order to increase the chances of a successful radiotherapy treatment the dose delivery to the tumor and the surrounding normal tissues has to be computed with high accuracy. Traditional dosimeters are accurate but single channel (ionization chambers and diodes) or non real-time (radiographic films) devices. At present there is no device water equivalent that can perform real-time and bidimensional measurements of a dose distribution. This article describes the development of a real-time dosimeter based on scintillating fibers for photon and electron beams; the fibers are made of polystyrene, that is water equivalent and thus tissue equivalent, allowing a direct dose calculation. Three prototypes (single and multichannel) have been assembled, consisting in small scintillators coupled to white fibers that carry the light to photomultiplier tubes. In this article the prototypes and the readout electronics are described, together with the results of the measurements with electron and photon beams with energy up to 20 MeV (produced by linear accelerators Varian Clinac 1800 and 2100CD).

  4. The photon magnetic moment problem revisited

    NASA Astrophysics Data System (ADS)

    Pérez Rojas, H.; Rodríguez Querts, E.

    2014-06-01

    The photon magnetic moment for radiation propagating in magnetized vacuum is defined as a pseudotensor quantity, proportional to the external electromagnetic field tensor. After expanding the eigenvalues of the polarization operator in powers of , we obtain approximate dispersion equations (cubic in ), and analytic solutions for the photon magnetic moment, valid for low momentum and/or large magnetic field. The paramagnetic photon experiences a redshift, with opposite sign to the gravitational one, which differs for parallel and perpendicular polarizations. It is due to the drain of photon transverse momentum and energy by the external field. By defining an effective transverse momentum, the constancy of the speed of light orthogonal to the field is guaranteed. We conclude that the propagation of the photon non-parallel to the magnetic direction behaves as if there is a quantum compression of the vacuum or a warp of space-time in an amount depending on its angle with regard to the field.

  5. [Radiotherapy of larynx cancers].

    PubMed

    Pointreau, Y; Lafond, C; Legouté, F; Trémolières, P; Servagi-Vernat, S; Giraud, P; Maingon, P; Calais, G; Lapeyre, M

    2016-09-01

    Intensity-modulated radiotherapy is the gold standard in the treatment of larynx cancers (except T1 glottic tumour). Early T1 and T2 tumours may be treated by exclusive radiation or surgery. For tumours requiring total laryngectomy (T2 or T3), induction chemotherapy followed by exclusive radiotherapy or concurrent chemoradiotherapy is possible. For T4 tumour, surgery must be proposed. The treatment of lymph nodes is based on the initial treatment of the primary tumour. In non-surgical procedure, in case of sequential radiotherapy, the curative dose is 70Gy and the prophylactic dose is 50Gy. An integrated simultaneous boost radiotherapy is allowed (70Gy in 2Gy per fraction and 56Gy in 1.8Gy per fraction or 70Gy in 2.12Gy per fraction). Postoperatively, radiotherapy is used in locally advanced cancer with dose levels based on pathologic criteria (66Gy for R1 resection, 50 to 54Gy for complete resection). Volume delineation was based on guidelines. PMID:27521037

  6. Radiotherapy of malignant melanoma

    SciTech Connect

    Cooper, J.S.

    1985-04-01

    The role of radiotherapy in the treatment of malignant melanoma is limited, and surgery generally forms the mainstay of medical practice. However, there are some circumstances in which radiotherapy should be considered the treatment of choice. Symptomatic metastatic lesions in bone or brain can effectively be palliated in a substantial proportion of instances. At the current stage of our knowledge, conventionally fractionated treatment of such lesions forms the standard against which other treatments should be measured. In contrast, metastatic lesions to skin or lymph nodes that do not overlie critical normal structures probably are better treated by high-dose-per-fraction techniques. Radiotherapy may play a definitive role in the treatment of lentigo maligna. The precise optimal energy of the beam to be used remains to be defined. Slightly more penetrating radiation appears to be required for lentigo maligna melanomas. Here, too, the optimal energy remains to be defined. The treatment of nonlentigenous melanomas primarily by radiotherapy is unproved in my opinion. Certainly, the data from the Princess Margaret Hospital is exciting, but I believe it must be corroborated by a well-designed trial before it can be accepted without question. Future directions in treatment of malignant melanoma are likely to include further trials of unconventional fractionation and the use of radiosensitizing agents in conjunction with radiotherapy. The time for dermatologists and radiation therapists to cooperate in such studies is at hand.

  7. Photon generator

    DOEpatents

    Srinivasan-Rao, Triveni

    2002-01-01

    A photon generator includes an electron gun for emitting an electron beam, a laser for emitting a laser beam, and an interaction ring wherein the laser beam repetitively collides with the electron beam for emitting a high energy photon beam therefrom in the exemplary form of x-rays. The interaction ring is a closed loop, sized and configured for circulating the electron beam with a period substantially equal to the period of the laser beam pulses for effecting repetitive collisions.

  8. Radiotherapy of inoperable lung cancer

    SciTech Connect

    Namer, M.; Lalanne, C.M.; Boublil, J.L.; Hery, M.; Chauvel, P.; Verschoore, J.; Aubanel, J.M.; Bruneton, J.N.

    1980-08-01

    Evaluation of loco-regional results obtained by radiotherapy for 31 patients with inoperable epidermoid lung cancer revealed objective remission (over 50%) in only 25% of patients. These results emphasize the limited effectiveness of radiotherapy in such cases and point out the need for increased research in radiotherapy techniques if survival rates are to be improved.

  9. Self-assembled tunable photonic hyper-crystals

    PubMed Central

    Smolyaninova, Vera N.; Yost, Bradley; Lahneman, David; Narimanov, Evgenii E.; Smolyaninov, Igor I.

    2014-01-01

    We demonstrate a novel artificial optical material, the “photonic hyper-crystal”, which combines the most interesting features of hyperbolic metamaterials and photonic crystals. Similar to hyperbolic metamaterials, photonic hyper-crystals exhibit broadband divergence in their photonic density of states due to the lack of usual diffraction limit on the photon wave vector. On the other hand, similar to photonic crystals, hyperbolic dispersion law of extraordinary photons is modulated by forbidden gaps near the boundaries of photonic Brillouin zones. Three dimensional self-assembly of photonic hyper-crystals has been achieved by application of external magnetic field to a cobalt nanoparticle-based ferrofluid. Unique spectral properties of photonic hyper-crystals lead to extreme sensitivity of the material to monolayer coatings of cobalt nanoparticles, which should find numerous applications in biological and chemical sensing. PMID:25027947

  10. Self-assembled tunable photonic hyper-crystals.

    PubMed

    Smolyaninova, Vera N; Yost, Bradley; Lahneman, David; Narimanov, Evgenii E; Smolyaninov, Igor I

    2014-01-01

    We demonstrate a novel artificial optical material, the "photonic hyper-crystal", which combines the most interesting features of hyperbolic metamaterials and photonic crystals. Similar to hyperbolic metamaterials, photonic hyper-crystals exhibit broadband divergence in their photonic density of states due to the lack of usual diffraction limit on the photon wave vector. On the other hand, similar to photonic crystals, hyperbolic dispersion law of extraordinary photons is modulated by forbidden gaps near the boundaries of photonic Brillouin zones. Three dimensional self-assembly of photonic hyper-crystals has been achieved by application of external magnetic field to a cobalt nanoparticle-based ferrofluid. Unique spectral properties of photonic hyper-crystals lead to extreme sensitivity of the material to monolayer coatings of cobalt nanoparticles, which should find numerous applications in biological and chemical sensing. PMID:25027947

  11. [Radiotherapy for brain metastases].

    PubMed

    Latorzeff, I; Antoni, D; Gaudaire-Josset, S; Feuvret, L; Tallet-Richard, A; Truc, G; Noël, G

    2016-09-01

    Radiotherapy for brain metastases has become more multifaceted. Indeed, with the improvement of the patient's life expectancy, side effects must be undeniably avoided and the retreatments or multiple treatments are common. The cognitive side effects should be warned and the most modern techniques of radiation therapy are used regularly to reach this goal. The new classifications of patients with brain metastases help guiding treatment more appropriately. Stereotactic radiotherapy has supplanted whole brain radiation therapy both for patients with metastases in place and for those who underwent surgery. Hippocampus protection is possible with intensity-modulated radiotherapy. Its relevance in terms of cognitive functioning should be more clearly demonstrated but the requirement, for using it, is increasingly strong. While addressing patients in palliative phase, the treatment of brain metastases is one of the localisations where technical thinking is the most challenging. PMID:27523410

  12. [Radiotherapy in Europe].

    PubMed

    Verheij, M; Slotman, B J

    2016-01-01

    Radiotherapy plays an important part in the curing of cancer patients and is an effective treatment for tumour-related symptoms. However, in many countries the level of access to this treatment modality is unacceptably low due to shortage of infrastructure, modern apparatus and trained staff. In Europe it is mainly the Eastern European countries that are behind in the provision of and accessibility to radiotherapy. Worldwide investment to narrow the gap would put an end to these undesirable differences. In addition, these investments would deliver economic benefits, especially in low-to-middle income countries. In this article, on the basis of a number of recently published reports, we discuss the differences that exist in the geographical spread of radiotherapy departments and the availability of apparatus within Europe. In conclusion we also take a short look at the Dutch situation. PMID:27334085

  13. Low-Dose Radiotherapy in Indolent Lymphoma

    SciTech Connect

    Rossier, Christine; Schick, Ulrike; Miralbell, Raymond; Mirimanoff, Rene O.; Weber, Damien C.; Ozsahin, Mahmut

    2011-11-01

    Purpose: To assess the response rate, duration of response, and overall survival after low-dose involved-field radiotherapy in patients with recurrent low-grade lymphoma or chronic lymphocytic leukemia (CLL). Methods and Materials: Forty-three (24 women, 19 men) consecutive patients with indolent lymphoma or CLL were treated with a total dose of 4 Gy (2 x 2 Gy) using 6- 18-MV photons. The median age was 73 years (range, 39-88). Radiotherapy was given either after (n = 32; 75%) or before (n = 11; 25%) chemotherapy. The median time from diagnosis was 48 months (range, 1-249). The median follow-up period was 20 months (range, 1-56). Results: The overall response rate was 90%. Twelve patients (28%) had a complete response, 15 (35%) had a partial response, 11 (26%) had stable disease, and 5 (11%) had progressive disease. The median overall survival for patients with a positive response (complete response/partial response/stable disease) was 41 months; for patients with progressive disease it was 6 months (p = 0.001). The median time to in-field progression was 21 months (range, 0-24), and the median time to out-field progression was 8 months (range, 0-40). The 3-year in-field control was 92% in patients with complete response (median was not reached). The median time to in-field progression was 9 months (range, 0.5-24) in patients with partial response and 6 months (range, 0.6-6) in those with stable disease (p < 0.05). Younger age, positive response to radiotherapy, and no previous chemotherapy were the best factors influencing the outcome. Conclusions: Low-dose involved-field radiotherapy is an effective treatment in the management of patients with recurrent low-grade lymphoma or CLL.

  14. [Radiotherapy in cancers of the oesophagus, the gastric cardia and the stomach].

    PubMed

    Créhange, G; Huguet, F; Quero, L; N'Guyen, T V; Mirabel, X; Lacornerie, T

    2016-09-01

    Localized oesophageal and gastric cancers have a poor prognosis. In oesophageal cancer, external radiotherapy combined with concomitant chemotherapy is accepted as part of the therapeutic armamentarium in a curative intent in the preoperative setting for resectable tumours; or without surgery in inoperable patients or non-resectable tumours due to wide local and/or regional extension. Data from the literature show conflicting results with no clinical evidence in favour of either a unique dose protocol or consensual target volume definition in the setting of exclusive chemoradiation. In the preoperative setting, chemoradiotherapy has become the standard in oesophageal cancer, even though there is no evidence that surgery may be beneficial in locally advanced tumours that respond to radiotherapy and chemotherapy. The main cause of failure after exclusive chemoradiotherapy in oesophageal cancer is locoregional relapse suggesting that doses and volumes usually considered may be inadequate. In gastric cancer, radiotherapy may be indicated postoperatively in patients with resected tumours that include less than D2 lymph node dissection or in the absence of perioperative chemotherapy. Preoperative chemoradiotherapy in gastric cancers is still under investigation. The evolving techniques of external radiotherapy, such as image-guided radiotherapy (IMRT) and volumetric modulated arctherapy (VMAT) have reduced the volume of lung and heart exposed to radiation, which seems to have diminished radiotherapy-related morbi-mortality rates. Given this, quality assurance for radiotherapy and protocols for radiotherapy delivery must be better standardized. This article on the indications for radiotherapy and the techniques used in oesophageal and gastric cancers is included in a special issue dedicated to national recommendations from the French society of radiation oncology (SFRO) on radiotherapy indications, planning, dose prescription, and techniques of radiotherapy delivery. PMID

  15. Radiotherapy for lung cancer

    SciTech Connect

    Bleehen, N.M.; Cox, J.D.

    1985-05-01

    The role of radiation therapy in the management of lung cancer was reviewed at a workshop held in Cambridge, England, in June 1984. It was concluded that there was a continuing role for radiation therapy in the primary management of small cell lung cancer, including the loco-regional treatment for patients with limited disease. Radical radiotherapy for patients with non-small cell carcinoma could be curative for a proportion of patients with limited disease. Careful planning and quality control was essential. Palliative radiotherapy provided useful treatment for many other patients. Other related aspects of treatment are also presented.

  16. Palliative radiotherapy for advanced malignancies in a changing oncologic landscape: guiding principles and practice implementation.

    PubMed

    Jones, Joshua A; Simone, Charles B

    2014-07-01

    Radiotherapy can provide safe, cost-effective, efficient palliation of various symptoms of advanced cancer with minimal side effects. Radiotherapy can palliate pain related to bone metastases and growing visceral metastases or primary cancers, neurologic symptoms related to brain and spine metastases, other symptoms including cough and dyspnea from advanced cancers in the lung, bleeding from various internal and external tumors, and obstructive symptoms. Palliative radiotherapy should be offered in the context of a multidisciplinary oncology team including medical oncologists, palliative care clinicians and various surgical and interventional subspecialists. The prescription of radiotherapy should balance the convenience and fewer side effects associated with short, hypofractionated courses of radiotherapy with the potential greater durability associated with longer courses of radiotherapy in patients with more prolonged life expectancies. The judicious use of advanced techniques in radiotherapy, including intensity-modulated radiotherapy and stereotactic radiotherapy (SRT), may be warranted in select patients, and they can potentially improve symptom control and durability but are associated with increased technical and economic costs. PMID:25841695

  17. Dose-response and failure pattern for bulky or barrel-shaped stage IB cervical cancer treated by combined photon irradiation and extrafascial hysterectomy

    SciTech Connect

    Maruyama, Y.; van Nagell, J.R.; Yoneda, J.; Donaldson, E.; Gallion, H.H.; Higgins, R.; Powell, D.; Kryscio, R.; Berner, B.

    1989-01-01

    From 1975 to 1987, 80 patients with bulky or barrel-shaped Stage IB cervical cancer were treated with preoperative irradiation and Cs-137 intracavitary implant therapy, before a planned extrafascial abdominal hysterectomy, using a consistent treatment policy. Of the hysterectomy specimens obtained, 37% were positive histologically at 89 +/- 2.3 days after the start of radiotherapy and at 4 to 6 weeks after the completion of radiation therapy. Sixty-three percent were negative after a total external and internal cervix irradiation dose of 9642 cGy at point T. The average point A dose contributed by intracavitary therapy was 2104 cGy. The survival rate at 5 years was 84%: At 10 years the survival rate was 78%. The failure pattern was analyzed for patients who had positive and negative specimens. The patients with positive specimens failed pelvically or pelvically and distantly. Patients with negative specimens failed in extrapelvic or distant metastatic sites. Preoperative radiotherapy led to excellent local and pelvic control of tumor, and the failures became predominantly distant metastases. The combined radiosurgical therapy was tolerated well and allowed surgical staging of disease. This permitted earlier and selective consideration of adjunctive therapy (i.e., paraaortic irradiation, chemotherapy, or chemoradiotherapy). The dose-response data give insight into the effects of photon radiotherapy on bulky or barrel Stage IB cervical cancers and correlate histologic status with failure pattern, outcome, and long-term survival.

  18. Characteristic evaluation of photoneutron in radiotherapy room using MCNPX

    NASA Astrophysics Data System (ADS)

    Park, E.-T.; Kim, J.-H.; Kim, C.-S.; Kang, S.-S.

    2015-08-01

    Linear accelerators are now playing a pivotal role in radiotherapy and high energy photon beams of a strength exceeding 8 MV have recently been mainly used. However, when using high energy photons, neutron contamination due to photonuclear reaction develops. This study focused on the dose distribution of photoneutrons emitted from a linear accelerator using Monte Carlo MCNPX code. MCNPX was used to simulate transportation of photoneutrons in the linear accelerator and the entire space of the radiotherapy room and is useful for calculating the flux, spectrum and absorbed dose. As result of the simulation, we could know that the neutron absorbed dose was as less as negligible when comparing to the photon absorbed dose in radiotherapy room. And it was found that the photoneutron flux increased substantially starting from 10 MV while the absorbed dose rose sharply between 10 MV and 12 MV. It was observed that although the ratio of thermal neutrons to fast neutrons was not altered as the energy increased, it was found that as the distance from the source increased the ratio of thermal neutrons rose markedly.

  19. Green photonics

    NASA Astrophysics Data System (ADS)

    Quan, Frederic

    2012-02-01

    Photonics, the broad merger of electronics with the optical sciences, encompasses such a wide swath of technology that its impact is almost universal in our everyday lives. This is a broad overview of some aspects of the industry and their contribution to the ‘green’ or environmental movement. The rationale for energy conservation is briefly discussed and the impact of photonics on our everyday lives and certain industries is described. Some opinions from industry are presented along with market estimates. References are provided to some of the most recent research in these areas.

  20. Photons Revisited

    NASA Astrophysics Data System (ADS)

    Batic, Matej; Begalli, Marcia; Han, Min Cheol; Hauf, Steffen; Hoff, Gabriela; Kim, Chan Hyeong; Kim, Han Sung; Grazia Pia, Maria; Saracco, Paolo; Weidenspointner, Georg

    2014-06-01

    A systematic review of methods and data for the Monte Carlo simulation of photon interactions is in progress: it concerns a wide set of theoretical modeling approaches and data libraries available for this purpose. Models and data libraries are assessed quantitatively with respect to an extensive collection of experimental measurements documented in the literature to determine their accuracy; this evaluation exploits rigorous statistical analysis methods. The computational performance of the associated modeling algorithms is evaluated as well. An overview of the assessment of photon interaction models and results of the experimental validation are presented.

  1. Frontiers in Radiotherapy for Early-Stage Invasive Breast Cancer

    PubMed Central

    Fisher, Christine M.; Rabinovitch, Rachel

    2014-01-01

    The development of breast-conserving treatment for early-stage breast cancer is one of the most important success stories in radiation oncology in the latter half of the twentieth century. Lumpectomy followed by radiotherapy provides an appealing alternative to mastectomy for many women. In recent years, there has been a shift in clinical investigational focus toward refinements in the methods of delivering adjuvant radiotherapy that provide shorter, more convenient schedules of external-beam radiotherapy and interstitial treatment. Expedited courses of whole-breast treatment have been demonstrated to be equivalent to traditional lengthier courses in terms of tumor control and cosmetic outcome and to provide an opportunity for cost efficiencies. PMID:25113764

  2. Recent advancements in toxicity prediction following prostate cancer radiotherapy.

    PubMed

    Ospina, J D; Fargeas, A; Dréan, G; Simon, A; Acosta, O; de Crevoisier, R

    2015-01-01

    In external beam radiotherapy for prostate cancer limiting toxicities for dose escalation are bladder and rectum toxicities. Normal tissue complication probability models aim at quantifying the risk of developping adverse events following radiotherapy. These models, originally proposed in the context of uniform irradiation, have evolved to implementations based on the state-of-the-art classification methods which are trained using empirical data. Recently, the use of image processing techniques combined with population analysis methods has led to a new generation of models to understand the risk of normal tissue complications following radiotherapy. This paper overviews those methods in the case of prostate cancer radiation therapy and propose some lines of future research. PMID:26737471

  3. The predicted relative risk of premature ovarian failure for three radiotherapy modalities in a girl receiving craniospinal irradiation

    NASA Astrophysics Data System (ADS)

    Pérez-Andújar, A.; Newhauser, W. D.; Taddei, P. J.; Mahajan, A.; Howell, R. M.

    2013-05-01

    In girls and young women, irradiation of the ovaries can reduce the number of viable ovarian primordial follicles, which may lead to premature ovarian failure (POF) and subsequently to sterility. One strategy to minimize this late effect is to reduce the radiation dose to the ovaries. A primary means of reducing dose is to choose a radiotherapy technique that avoids irradiating nearby normal tissue; however, the relative risk of POF (RRPOF) due to the various therapeutic options has not been assessed. This study compared the predicted RRPOF after craniospinal proton radiotherapy, conventional photon radiotherapy (CRT) and intensity-modulated photon radiotherapy (IMRT). We calculated the equivalent dose delivered to the ovaries of an 11-year-old girl from therapeutic and stray radiation. We then predicted the percentage of ovarian primordial follicles killed by radiation and used this as a measure of the RRPOF; we also calculated the ratio of the relative risk of POF (RRRPOF) among the three radiotherapies. Proton radiotherapy had a lower RRPOF than either of the other two types. We also tested the sensitivity of the RRRPOF between photon and proton therapies to the anatomic position of the ovaries, i.e., proximity to the treatment field (2 ≤ RRRPOF ≤ 10). We found that CRT and IMRT have higher risks of POF than passive-scattering proton radiotherapy (PRT) does, regardless of uncertainties in the ovarian location. Overall, PRT represents a lower RRPOF over the two other modalities.

  4. Clinical Outcomes and Toxicity of Proton Radiotherapy for Breast Cancer.

    PubMed

    Verma, Vivek; Shah, Chirag; Mehta, Minesh P

    2016-06-01

    Proton beam radiotherapy (PBT) represents a rapidly expanding modality for the treatment of several malignancies. We examined the current state of PBT for breast cancer to evaluate its role in the modern era of breast radiotherapy. Systematic searches were performed using PubMed, EMBASE, and abstracts from the American Society for Radiation Oncology, American Society of Clinical Oncology, and Particle Therapy Co-Operative Group of North America annual meetings, using the Preferred Reporting Items for Systematic Reviews and Meta-Analyses guidelines. Nine original investigations were analyzed. Despite the dearth of overall data, skin toxicity after PBT might be equivalent or better than that of photons. Conventionally fractionated breast/chest wall PBT produces grade 1 dermatitis rates of approximately 25% and grade 2 dermatitis in 71% to 75%. This is comparable or improved over the published rates for photons. The incidence of esophagitis was decreased if the target coverage was compromised in the medial supraclavicular volume, a finding that echoes previous results with photon radiotherapy. The rates of esophagitis were also comparable to the previous data for photons. Using PBT-based accelerated partial breast irradiation, the rates of seroma/hematoma and fat necrosis were comparable to those reported in the existing data. Radiation pneumonitis and rib fractures remain rare. PBT offers excellent potential to minimize the risk of cardiac events, keeping the mean heart dose at ≤ 1 Gy. However, definitive clinical experiences remain sparse. The recently begun randomized trial of protons versus photons will further aid in providing robust conclusions. PMID:26995159

  5. [Crossed audit of the quality management system: Optimization of professional practices in radiotherapy].

    PubMed

    Leroy, É; Ponsard, N

    2015-10-01

    A working group within the French association of radiotherapy quality managers (AFQSR) proposed to implement an inter-institution audit among radiotherapy quality managers to share best practices, experience, and to have an external measurement of the effectiveness of the quality control processes implemented. A checklist was devised based on the French nuclear safety authority guide N(o) 5 and a procedure was formalized. The audit focuses on the effectiveness of the quality management process in radiotherapy. This article details the rationale for the project and conduct of the audit. PMID:26344432

  6. Automated External Defibrillator

    MedlinePlus

    ... from the NHLBI on Twitter. What Is an Automated External Defibrillator? An automated external defibrillator (AED) is a portable device that ... Institutes of Health Department of Health and Human Services USA.gov

  7. Dosimetric Considerations to Determine the Optimal Technique for Localized Prostate Cancer Among External Photon, Proton, or Carbon-Ion Therapy and High-Dose-Rate or Low-Dose-Rate Brachytherapy

    SciTech Connect

    Georg, Dietmar

    2014-03-01

    Purpose: To assess the dosimetric differences among volumetric modulated arc therapy (VMAT), scanned proton therapy (intensity-modulated proton therapy, IMPT), scanned carbon-ion therapy (intensity-modulated carbon-ion therapy, IMIT), and low-dose-rate (LDR) and high-dose-rate (HDR) brachytherapy (BT) treatment of localized prostate cancer. Methods and Materials: Ten patients were considered for this planning study. For external beam radiation therapy (EBRT), planning target volume was created by adding a margin of 5 mm (lateral/anterior–posterior) and 8 mm (superior–inferior) to the clinical target volume. Bladder wall (BW), rectal wall (RW), femoral heads, urethra, and pelvic tissue were considered as organs at risk. For VMAT and IMPT, 78 Gy(relative biological effectiveness, RBE)/2 Gy were prescribed. The IMIT was based on 66 Gy(RBE)/20 fractions. The clinical target volume planning aims for HDR-BT ({sup 192}Ir) and LDR-BT ({sup 125}I) were D{sub 90%} ≥34 Gy in 8.5 Gy per fraction and D{sub 90%} ≥145 Gy. Both physical and RBE-weighted dose distributions for protons and carbon-ions were converted to dose distributions based on 2-Gy(IsoE) fractions. From these dose distributions various dose and dose–volume parameters were extracted. Results: Rectal wall exposure 30-70 Gy(IsoE) was reduced for IMIT, LDR-BT, and HDR-BT when compared with VMAT and IMPT. The high-dose region of the BW dose–volume histogram above 50 Gy(IsoE) of IMPT resembled the VMAT shape, whereas all other techniques showed a significantly lower high-dose region. For all 3 EBRT techniques similar urethra D{sub mean} around 74 Gy(IsoE) were obtained. The LDR-BT results were approximately 30 Gy(IsoE) higher, HDR-BT 10 Gy(IsoE) lower. Normal tissue and femoral head sparing was best with BT. Conclusion: Despite the different EBRT prescription and fractionation schemes, the high-dose regions of BW and RW expressed in Gy(IsoE) were on the same order of magnitude. Brachytherapy techniques

  8. Photon Collider Physics with Real Photon Beams

    SciTech Connect

    Gronberg, J; Asztalos, S

    2005-11-03

    Photon-photon interactions have been an important probe into fundamental particle physics. Until recently, the only way to produce photon-photon collisions was parasitically in the collision of charged particles. Recent advances in short-pulse laser technology have made it possible to consider producing high intensity, tightly focused beams of real photons through Compton scattering. A linear e{sup +}e{sup -} collider could thus be transformed into a photon-photon collider with the addition of high power lasers. In this paper they show that it is possible to make a competitive photon-photon collider experiment using the currently mothballed Stanford Linear Collider. This would produce photon-photon collisions in the GeV energy range which would allow the discovery and study of exotic heavy mesons with spin states of zero and two.

  9. Experimental realization of a two-photon Raman laser

    NASA Astrophysics Data System (ADS)

    Brown, William J.

    1999-11-01

    This thesis describes the development of a novel quantum oscillator known as a two-photon Raman laser. It is based on two-photon stimulated emission in strongly driven potassium atoms. Two-photon lasers were first proposed in the 1960's, but only recently have such devices been experimentally realized. The two-photon Raman laser is an important step forward as it provides the first opportunity to study the turn-on behavior, instabilities, and noise properties of a pure two-photon optical device. The necessary ingredients for a two-photon laser are a medium displaying two-photon laser beam amplification and an optical resonator. In my two-photon Raman laser the amplification arises from a multi-photon process in which state-prepared potassium atoms undergo two-photon Raman transitions. This amplification process was studied using a high-density, small-Doppler-width potassium atomic beam that was driven by a strong pump laser and probed by a weak probe laser. I observed two-photon Raman amplification for a range of pump laser frequencies, atomic beam number densities, and probe beam powers. The two-photon Raman gain is linearly dependent on the input probe power as expected for a two-photon process. This gain mechanism is also spectrally isolated from other mechanisms occurring in strongly driven potassium atoms. The optical resonator consists of a sub-confocal high finesse cavity. The cavity is constructed so that the two-photon Raman process will lase while all other processes are suppressed. The cavity buildup is sufficient to support lasing given the maximum two-photon Raman gain observed in the amplification experiment. Using this apparatus I have observed two-photon lasing. In agreement with theoretical predictions, an external photon source is required to initiate two-photon lasing. I initiated the two-photon laser using an externally injected pulse of light and using a frequency degenerate one-photon process. The two-photon Raman laser threshold was mapped as

  10. Rapid onset of cutaneous angiosarcoma after radiotherapy for breast carcinoma

    SciTech Connect

    Otis, C.N.; Peschel, R.; McKhann, C.; Merino, M.J.; Duray, P.H.

    1986-06-01

    Malignant neoplasms known to develop following external beam radiation include squamous cell carcinoma, osteosarcoma, chondrosarcoma, malignant fibrous histiocytoma, mixed mullerian tumors, malignant schwannoma, myelogenous leukemia and angiosarcoma. Latency periods of many years characterize the onset of these tumors following the exposure. Cutaneous angiosarcoma following radiotherapy for breast carcinoma has been rarely documented, occurring up to 13 years postirradiation. Two cases of this entity are reported occurring 37 months postradiotherapy at the site of mastectomy performed for mammary duct carcinoma.

  11. External artery heat pipe

    NASA Technical Reports Server (NTRS)

    Gernert, Nelson J. (Inventor); Ernst, Donald M. (Inventor); Shaubach, Robert M. (Inventor)

    1989-01-01

    An improved heat pipe with an external artery. The longitudinal slot in the heat pipe wall which interconnects the heat pipe vapor space with the external artery is completely filled with sintered wick material and the wall of the external artery is also covered with sintered wick material. This added wick structure assures that the external artery will continue to feed liquid to the heat pipe evaporator even if a vapor bubble forms within and would otherwise block the liquid transport function of the external artery.

  12. Radioiodine and radiotherapy in the management of thyroid cancers

    SciTech Connect

    Simpson, W.J. )

    1990-06-01

    Radioiodine is an important adjuvant treatment in the management of resectable papillary and follicular thyroid cancers in all patients except those with the best prognostic features. External radiation is also an important adjuvant therapy in these patients, especially those with tumors that extend beyond the thyroid gland and invade the trachea, esophagus, nerves, and blood vessels; it is especially important in treating patients whose tumors do not concentrate radioiodine. Radioiodine may be curative in patients with microscopic distant metastases demonstrated by radioiodine scanning. Even unresectable primary papillary and follicular cancers may be eradicated by combined therapy with radioiodine and radiotherapy. Radioiodine plays no significant role in the treatment of medullary or anaplastic thyroid cancers, but external radiation may eradicate microscopic thyroid bed or nodal disease when persistent disease is indicated by elevated calcitonin levels in medullary thyroid cancer patients. Anaplastic thyroid cancers are usually unresectable and are not eradicated by conventional radiotherapy or by any of the novel radiation techniques, with or without chemotherapy. In all types of thyroid cancer, external radiotherapy may produce beneficial palliative results in patients with distant metastases, but the use of radioiodine should always be explored in papillary and follicular thyroid cancer patients. 30 references.

  13. Integrated photonics

    NASA Astrophysics Data System (ADS)

    Gondarenko, Alexander A.

    In 1958 the first integrated circuit was demonstrated to combine transistors, resistors, and capacitors [36]. To this date fabrication technology has been driven by the growing demand for monolithically constructed, densely packed electronic components. The exponentially shrinking device size decreased the feature dimensions from 10 microns to 32 nm and grew transistor count from 2,300 to over 2,000,000,000 in Intel's 4004 and Intel Kentsfield XE microprocessors. The benefits of micro- and nano-fabrication was not limited to just computer chips. MEMs, spintronic, microfluidics, and integrated photonics were all made possible by the ever expanding ability to form complex geometries, on a wide variety of materials, on a micron and submicron scale. This dissertation is part of an effort to design and fabricate novel integrated photonic devices compatible with standard electron beam and photo lithography and utilize a readily available material base. We aim to create devices with a decreased footprint on a chip and operate in the infrared, visible, and UV spectra. We present two general sections, the first is a theoretical effort to find the fundamental design geometries for a variety of optical problems. The second section is an experimental demonstration of techniques and devices for novel optical phenomena in an integrated package. In the theoretical section we develop and apply computational evolutionary algorithms to explore problems of light confinement, coupling, and guiding in two and three dimensional device geometries. Our general aim is to find a global limit to optimal device geometry and performance given a set of constrains. Experimentally, we demonstrate an efficient design and a fabrication process for a short development cycle of photonic devices. For the design part of the workflow, we develop a computational approach to explore device geometries with minimum initial assumptions for a variety of photonic problems. For the fabrication part of the

  14. Organ-specific radiation-induced cancer risk estimates due to radiotherapy for benign pigmented villonodular synovitis

    NASA Astrophysics Data System (ADS)

    Mazonakis, Michalis; Tzedakis, Antonis; Lyraraki, Efrossyni; Damilakis, John

    2016-09-01

    Pigmented villonodular synovitis (PVNS) is a benign disease affecting synovial membranes of young and middle-aged adults. The aggressive treatment of this disorder often involves external-beam irradiation. This study was motivated by the lack of data relating to the radiation exposure of healthy tissues and radiotherapy-induced cancer risk. Monte Carlo methodology was employed to simulate a patient’s irradiation for PVNS in the knee and hip joints with a 6 MV photon beam. The average radiation dose received by twenty-two out-of-field critical organs of the human body was calculated. These calculations were combined with the appropriate organ-, age- and gender-specific risk coefficients of the BEIR-VII model to estimate the lifetime probability of cancer development. The risk for carcinogenesis to colon, which was partly included in the treatment fields used for hip irradiation, was determined with a non-linear mechanistic model and differential dose-volume histograms obtained by CT-based 3D radiotherapy planning. Risk assessments were compared with the nominal lifetime intrinsic risk (LIR) values. Knee irradiation to 36 Gy resulted in out-of-field organ doses of 0.2–24.6 mGy. The corresponding range from hip radiotherapy was 1.2–455.1 mGy whereas the organ equivalent dose for the colon was up to 654.9 mGy. The organ-specific cancer risks from knee irradiation for PVNS were found to be inconsequential since they were at least 161.5 times lower than the LIRs irrespective of the patient’s age and gender. The bladder and colon cancer risk from radiotherapy in the hip joint was up to 3.2 and 6.6 times smaller than the LIR, respectively. These cancer risks may slightly elevate the nominal incidence rates and they should not be ignored during the patient’s treatment planning and follow-up. The probabilities for developing any other solid tumor were more than 20 times lower than the LIRs and, therefor