Concomitant chemoradiotherapy with high dose rate brachytherapy ...

African Journals Online (AJOL)

Concomitant chemoradiotherapy with high dose rate brachytherapy as a definitive treatment modality for locally advanced cervical cancer. T Refaat, A Elsaid, N Lotfy, K Kiel, W Small Jr, P Nickers, E Lartigau ...

High dose rate (HDR) and low dose rate (LDR) interstitial irradiation (IRT) of the rat spinal cord

International Nuclear Information System (INIS)

Pop, Lucas A.M.; Plas, Mirjam van der; Skwarchuk, Mark W.; Hanssen, Alex E.J.; Kogel, Albert J. van der

1997-01-01

Purpose: To describe a newly developed technique to study radiation tolerance of rat spinal cord to continuous interstitial irradiation (IRT) at different dose rates. Material and methods: Two parallel catheters are inserted just laterally on each side of the vertebral bodies from the level of Th 10 to L 4 . These catheters are afterloaded with two 192 Ir wires of 4 cm length each (activity 1-2.3 mCi/cm) for the low dose rate (LDR) IRT or connected to the HDR micro-Selectron for the high dose rate (HDR) IRT. Spinal cord target volume is located at the level of Th 12 -L 2 . Due to the rapid dose fall-off around the implanted sources, a dose inhomogeneity across the spinal cord thickness is obtained in the dorso-ventral direction. Using the 100% reference dose (rate) at the ventral side of the spinal cord to prescribe the dose, experiments have been carried out to obtain complete dose response curves at average dose rates of 0.49, 0.96 and 120 Gy/h. Paralysis of the hind-legs after 5-6 months and histopathological examination of the spinal cord of each irradiated rat are used as experimental endpoints. Results: The histopathological damage seen after irradiation is clearly reflected the inhomogeneous dose distribution around the implanted catheters, with the damage predominantly located in the dorsal tract of the cord or dorsal roots. With each reduction in average dose rate, spinal cord radiation tolerance is significantly increased. When the dose is prescribed at the 100% reference dose rate, the ED 50 (induction of paresis in 50% of the animals) for the HDR-IRT is 17.3 Gy. If the average dose rate is reduced from 120 Gy/h to 0.96 or 0.49 Gy/h, a 2.9- or 4.7-fold increase in the ED 50 values to 50.3 Gy and 80.9 Gy is observed; for the dose prescribed at the 150% reference dose rate (dorsal side of cord) ED 50 values are 26.0, 75.5 and 121.4 Gy, respectively. Using different types of analysis and in dependence of the dose prescription and reference dose rate, the �

High Dose-Rate Versus Low Dose-Rate Brachytherapy for Lip Cancer

International Nuclear Information System (INIS)

Ghadjar, Pirus; Bojaxhiu, Beat; Simcock, Mathew; Terribilini, Dario; Isaak, Bernhard; Gut, Philipp; Wolfensberger, Patrick; Brömme, Jens O.; Geretschläger, Andreas; Behrensmeier, Frank; Pica, Alessia; Aebersold, Daniel M.

2012-01-01

Purpose: To analyze the outcome after low-dose-rate (LDR) or high-dose-rate (HDR) brachytherapy for lip cancer. Methods and Materials: One hundred and three patients with newly diagnosed squamous cell carcinoma of the lip were treated between March 1985 and June 2009 either by HDR (n = 33) or LDR brachytherapy (n = 70). Sixty-eight patients received brachytherapy alone, and 35 received tumor excision followed by brachytherapy because of positive resection margins. Acute and late toxicity was assessed according to the Common Terminology Criteria for Adverse Events 3.0. Results: Median follow-up was 3.1 years (range, 0.3–23 years). Clinical and pathological variables did not differ significantly between groups. At 5 years, local recurrence-free survival, regional recurrence-free survival, and overall survival rates were 93%, 90%, and 77%. There was no significant difference for these endpoints when HDR was compared with LDR brachytherapy. Forty-two of 103 patients (41%) experienced acute Grade 2 and 57 of 103 patients (55%) experienced acute Grade 3 toxicity. Late Grade 1 toxicity was experienced by 34 of 103 patients (33%), and 5 of 103 patients (5%) experienced late Grade 2 toxicity; no Grade 3 late toxicity was observed. Acute and late toxicity rates were not significantly different between HDR and LDR brachytherapy. Conclusions: As treatment for lip cancer, HDR and LDR brachytherapy have comparable locoregional control and acute and late toxicity rates. HDR brachytherapy for lip cancer seems to be an effective treatment with acceptable toxicity.

Endovascular Management of Acute Limb Ischemia.

LENUS (Irish Health Repository)

Hynes, Brian G

2011-09-14

Despite major advances in pharmacologic and endovascular therapies, acute limb ischemia (ALI) continues to result in significant morbidity and mortality. The incidence of ALI may be as high as 13-17 cases per 100,000 people per year, with mortality rates approaching 18% in some series. This review will address the contemporary endovascular management of ALI encompassing pharmacologic and percutaneous interventional treatment strategies.

Radiobiological modelling of dose-gradient effects in low dose rate, high dose rate and pulsed brachytherapy

International Nuclear Information System (INIS)

Armpilia, C; Dale, R G; Sandilos, P; Vlachos, L

2006-01-01

This paper presents a generalization of a previously published methodology which quantified the radiobiological consequences of dose-gradient effects in brachytherapy applications. The methodology uses the linear-quadratic (LQ) formulation to identify an equivalent biologically effective dose (BED eq ) which, if applied uniformly to a specified tissue volume, would produce the same net cell survival as that achieved by a given non-uniform brachytherapy application. Multiplying factors (MFs), which enable the equivalent BED for an enclosed volume to be estimated from the BED calculated at the dose reference surface, have been calculated and tabulated for both spherical and cylindrical geometries. The main types of brachytherapy (high dose rate (HDR), low dose rate (LDR) and pulsed (PB)) have been examined for a range of radiobiological parameters/dimensions. Equivalent BEDs are consistently higher than the BEDs calculated at the reference surface by an amount which depends on the treatment prescription (magnitude of the prescribed dose) at the reference point. MFs are closely related to the numerical BED values, irrespective of how the original BED was attained (e.g., via HDR, LDR or PB). Thus, an average MF can be used for a given prescribed BED as it will be largely independent of the assumed radiobiological parameters (radiosensitivity and α/β) and standardized look-up tables may be applicable to all types of brachytherapy treatment. This analysis opens the way to more systematic approaches for correlating physical and biological effects in several types of brachytherapy and for the improved quantitative assessment and ranking of clinical treatments which involve a brachytherapy component

Rectal dose assessment in patients submitted to high-dose-rate brachytherapy for uterine cervix cancer

International Nuclear Information System (INIS)

Oliveira, Jetro Pereira de; Batista, Delano Valdivino Santos; Bardella, Lucia Helena; Carvalho, Arnaldo Rangel

2009-01-01

Objective: The present study was aimed at developing a thermoluminescent dosimetric system capable of assessing the doses delivered to the rectum of patients submitted to high-dose-rate brachytherapy for uterine cervix cancer. Materials and methods: LiF:Mg,Ti,Na powder was the thermoluminescent material utilized for evaluating the rectal dose. The powder was divided into small portions (34 mg) which were accommodated in a capillary tube. This tube was placed into a rectal probe that was introduced into the patient's rectum. Results: The doses delivered to the rectum of six patients submitted to high-dose-rate brachytherapy for uterine cervix cancer evaluated by means of thermoluminescent dosimeters presented a good agreement with the planned values based on two orthogonal (anteroposterior and lateral) radiographic images of the patients. Conclusion: The thermoluminescent dosimetric system developed in the present study is simple and easy to be utilized as compared to other rectal dosimetry methods. The system has shown to be effective in the evaluation of rectal doses in patients submitted to high-dose-rate brachytherapy for uterine cervix cancer. (author)

Endovascular management of delayed post-pancreatectomy haemorrhage

International Nuclear Information System (INIS)

Pottier, Edwige; Ronot, Maxime; Vilgrain, Valerie; Gaujoux, Sebastien; Cesaretti, Manuela; Barbier, Louise; Sauvanet, Alain

2016-01-01

To assess the patient outcome after endovascular treatment of delayed post-pancreatectomy haemorrhage (PPH) as first-line treatment. Between January 2005 and November 2013, all consecutive patients referred for endovascular treatment of PPH were included. Active bleeding, pseudoaneurysms, collections and the involved artery were recorded on pretreatment CT. Endovascular procedures were classified as technical success (source of bleeding identified on angiogram and treated), technical failure (source of bleeding identified but incompletely treated) and abstention (no abnormality identified, no treatment performed). Factors associated with rebleeding were analysed. Sixty-nine patients (53 men) were included (mean 59 years old (32-75)). Pretreatment CT showed 27 (39 %) active bleeding. In 22 (32 %) cases, no involved artery was identified. Technical success, failure and abstention were observed in 48 (70 %), 9 (13 %) and 12 patients (17 %), respectively. Thirty patients (43 %) experienced rebleeding. Rebleeding rates were 29 %, 58 % and 100 % in case of success, abstention and failure (p < 0.001). Treatment failure/abstention was the only factor associated with rebleeding. Overall, 74 % of the patients were successfully treated by endovascular procedure(s) alone. After a first endovascular procedure for PPH, the rebleeding rate is high and depends upon the success of the procedure. Most patients are successfully treated by endovascular approach(es) alone. (orig.)

Endovascular management of delayed post-pancreatectomy haemorrhage

Energy Technology Data Exchange (ETDEWEB)

Pottier, Edwige [Beaujon Hospital, University Hospitals Paris Nord Val de Seine, Department of Radiology, Clichy, Hauts-de-Seine (France); Ronot, Maxime; Vilgrain, Valerie [Beaujon Hospital, University Hospitals Paris Nord Val de Seine, Department of Radiology, Clichy, Hauts-de-Seine (France); University Paris Diderot, Paris (France); INSERM U1149, centre de recherche biomedicale Bichat-Beaujon, CRB3, Paris (France); Gaujoux, Sebastien; Cesaretti, Manuela; Barbier, Louise [APHP, University Hospitals Paris Nord Val de Seine, Beaujon, Department of Surgery, Clichy, Hauts-de-Seine (France); Sauvanet, Alain [University Paris Diderot, Paris (France); APHP, University Hospitals Paris Nord Val de Seine, Beaujon, Department of Surgery, Clichy, Hauts-de-Seine (France)

2016-10-15

To assess the patient outcome after endovascular treatment of delayed post-pancreatectomy haemorrhage (PPH) as first-line treatment. Between January 2005 and November 2013, all consecutive patients referred for endovascular treatment of PPH were included. Active bleeding, pseudoaneurysms, collections and the involved artery were recorded on pretreatment CT. Endovascular procedures were classified as technical success (source of bleeding identified on angiogram and treated), technical failure (source of bleeding identified but incompletely treated) and abstention (no abnormality identified, no treatment performed). Factors associated with rebleeding were analysed. Sixty-nine patients (53 men) were included (mean 59 years old (32-75)). Pretreatment CT showed 27 (39 %) active bleeding. In 22 (32 %) cases, no involved artery was identified. Technical success, failure and abstention were observed in 48 (70 %), 9 (13 %) and 12 patients (17 %), respectively. Thirty patients (43 %) experienced rebleeding. Rebleeding rates were 29 %, 58 % and 100 % in case of success, abstention and failure (p < 0.001). Treatment failure/abstention was the only factor associated with rebleeding. Overall, 74 % of the patients were successfully treated by endovascular procedure(s) alone. After a first endovascular procedure for PPH, the rebleeding rate is high and depends upon the success of the procedure. Most patients are successfully treated by endovascular approach(es) alone. (orig.)

Transperineal high-dose-rate interstitial radiation therapy in the management of gynecologic malignancies

Energy Technology Data Exchange (ETDEWEB)

Itami, Jun; Hara, Ryuseke; Kozuka, Takuyou; Yamashita, Hideomi; Nakajima, Kaori; Shibata, Kouji; Abe, Yoshihisa; Fuse, Masashi; Ito, Masashi [International Medical Center of Japan, Tokyo (Japan). Dept. of Radiation Therapy and Oncology

2003-11-01

Background: High-dose-rate interstitial radiation therapy is a newly introduced modality, and its role in the management of gynecologic malignancies remains to be studied. Clinical experience in high-dose-rate interstitial radiation therapy was retrospectively investigated. Patients and Methods: Eight patients with primary and nine with recurrent gynecologic malignancies underwent high-dose-rate interstitial radiation therapy with/without external-beam irradiation. Fractional dose of the high-dose-rate interstitial radiation therapy ranged between 4 and 6 Gy with total doses of 15-54 Gy. Interstitial irradiation was performed twice daily with an interval of > 6 h. Results: 2-year local control rate was 75% for primary treatment and 47% for treatment of recurrence (p = 0.46). Maximum tumor size had a statistically significant impact on local control (p < 0.002). Grade 2 and 4 late complications were seen in five patients, and the incidence was significantly higher in patients with a larger volume enclosed by the prescribed fractional dose of high-dose-rate interstitial radiation therapy. The incidence of grade 2 and 4 complications at 18 months was 78% and 0% with a volume > 100 cm{sup 3} and {<=} 100 cm{sup 3}, respectively (p < 0.04). Conclusion: Although high-dose-rate interstitial radiation therapy is a promising modality, it must be applied cautiously to patients with bulky tumors because of the high incidence of serious complications. (orig.)

High dose rate brachytherapy for oral cancer.

Science.gov (United States)

Yamazaki, Hideya; Yoshida, Ken; Yoshioka, Yasuo; Shimizutani, Kimishige; Furukawa, Souhei; Koizumi, Masahiko; Ogawa, Kazuhiko

2013-01-01

Brachytherapy results in better dose distribution compared with other treatments because of steep dose reduction in the surrounding normal tissues. Excellent local control rates and acceptable side effects have been demonstrated with brachytherapy as a sole treatment modality, a postoperative method, and a method of reirradiation. Low-dose-rate (LDR) brachytherapy has been employed worldwide for its superior outcome. With the advent of technology, high-dose-rate (HDR) brachytherapy has enabled health care providers to avoid radiation exposure. This therapy has been used for treating many types of cancer such as gynecological cancer, breast cancer, and prostate cancer. However, LDR and pulsed-dose-rate interstitial brachytherapies have been mainstays for head and neck cancer. HDR brachytherapy has not become widely used in the radiotherapy community for treating head and neck cancer because of lack of experience and biological concerns. On the other hand, because HDR brachytherapy is less time-consuming, treatment can occasionally be administered on an outpatient basis. For the convenience and safety of patients and medical staff, HDR brachytherapy should be explored. To enhance the role of this therapy in treatment of head and neck lesions, we have reviewed its outcomes with oral cancer, including Phase I/II to Phase III studies, evaluating this technique in terms of safety and efficacy. In particular, our studies have shown that superficial tumors can be treated using a non-invasive mold technique on an outpatient basis without adverse reactions. The next generation of image-guided brachytherapy using HDR has been discussed. In conclusion, although concrete evidence is yet to be produced with a sophisticated study in a reproducible manner, HDR brachytherapy remains an important option for treatment of oral cancer.

Estimation of the transit dose component in high dose rate brachytherapy

International Nuclear Information System (INIS)

Garcia Romero, A.; Millan Cebrian, E.; Lozano Flores, F.J.; Lope Lope, R.; Canellas Anoz, M.

2001-01-01

Current high dose rate brachytherapy (HDR) treatment planning systems usually calculate dose only from source stopping positions (stationary component), but fails to account for the administered dose when the source is moving (dynamic component or transit dose). Numerical values of this transit dose depends upon the source velocity, implant geometry, source activity and prescribed dose. In some HDR treatments using particular geometry the transit dose cannot be ignored because it increases the dose at the prescriptions points and also could increase potential late tissue complications as predicted by the linear quadratic model. International protocols recommend to verify this parameter. The aim of this paper has been to establish a procedure for the transit dose calculation for the Gammamed 12i equipment at the RT Department in the Clinical University Hospital (Zaragoza-Spain). A numeric algorithm was implemented based on a dynamic point approximation for the moving HDR source and the calculated results for the entrance-exit transit dose was compared with TLD measurements made in some discrete points. (author) [es

Development of computerized dose planning system and applicator for high dose rate remote afterloading irradiation

Energy Technology Data Exchange (ETDEWEB)

Choi, T. J. [Keimyung Univ., Taegu (Korea); Kim, S. W. [Fatima Hospital, Taegu (Korea); Kim, O. B.; Lee, H. J.; Won, C. H. [Keimyung Univ., Taegu (Korea); Yoon, S. M. [Dong-a Univ., Pusan (Korea)

2000-04-01

To design and fabricate of the high dose rate source and applicators which are tandem, ovoids and colpostat for OB/Gyn brachytherapy includes the computerized dose planning system. Designed the high dose rate Ir-192 source with nuclide atomic power irradiation and investigated the dose characteristics of fabricated brachysource. We performed the effect of self-absorption and determining the gamma constant and output factor and determined the apparent activity of designed source. he automated computer planning system provided the 2D distribution and 3D includes analysis programs. Created the high dose rate source Ir-192, 10 Ci(370GBq). The effective attenuation factor from the self-absorption and source wall was examined to 0.55 of the activity of bare source and this factor is useful for determination of the apparent activity and gamma constant 4.69 Rcm{sup 2}/mCi-hr. Fabricated the colpostat was investigated the dose distributions of frontal, axial and sagittal plane in intra-cavitary radiation therapy for cervical cancer. The reduce dose at bladder and rectum area was found about 20 % of original dose. The computerized brachytherapy planning system provides the 2-dimensional isodose and 3-D include the dose-volume histogram(DVH) with graphic-user-interface mode. emoted afterloading device was built for experiment of created Ir-192 source with film dosimetry within {+-}1 mm discrepancy. 34 refs., 25 figs., 11 tabs. (Author)

High dose rate brachytherapy for oral cancer

International Nuclear Information System (INIS)

Yamazaki, Hideya; Yoshida, Ken; Yoshioka, Yasuo; Shimizutani, Kimishige; Koizumi, Masahiko; Ogawa, Kazuhiko; Furukawa, Souhei

2013-01-01

Brachytherapy results in better dose distribution compared with other treatments because of steep dose reduction in the surrounding normal tissues. Excellent local control rates and acceptable side effects have been demonstrated with brachytherapy as a sole treatment modality, a postoperative method, and a method of reirradiation. Low-dose-rate (LDR) brachytherapy has been employed worldwide for its superior outcome. With the advent of technology, high-dose-rate (HDR) brachytherapy has enabled health care providers to avoid radiation exposure. This therapy has been used for treating many types of cancer such as gynecological cancer, breast cancer, and prostate cancer. However, LDR and pulsed-dose-rate interstitial brachytherapies have been mainstays for head and neck cancer. HDR brachytherapy has not become widely used in the radiotherapy community for treating head and neck cancer because of lack of experience and biological concerns. On the other hand, because HDR brachytherapy is less time-consuming, treatment can occasionally be administered on an outpatient basis. For the convenience and safety of patients and medical staff, HDR brachytherapy should be explored. To enhance the role of this therapy in treatment of head and neck lesions, we have reviewed its outcomes with oral cancer, including Phase I/II to Phase III studies, evaluating this technique in terms of safety and efficacy. In particular, our studies have shown that superficial tumors can be treated using a non-invasive mold technique on an outpatient basis without adverse reactions. The next generation of image-guided brachytherapy using HDR has been discussed. In conclusion, although concrete evidence is yet to be produced with a sophisticated study in a reproducible manner, HDR brachytherapy remains an important option for treatment of oral cancer. (author)

Radiation Parameters of High Dose Rate Iridium -192 Sources

Science.gov (United States)

Podgorsak, Matthew B.

A lack of physical data for high dose rate (HDR) Ir-192 sources has necessitated the use of basic radiation parameters measured with low dose rate (LDR) Ir-192 seeds and ribbons in HDR dosimetry calculations. A rigorous examination of the radiation parameters of several HDR Ir-192 sources has shown that this extension of physical data from LDR to HDR Ir-192 may be inaccurate. Uncertainty in any of the basic radiation parameters used in dosimetry calculations compromises the accuracy of the calculated dose distribution and the subsequent dose delivery. Dose errors of up to 0.3%, 6%, and 2% can result from the use of currently accepted values for the half-life, exposure rate constant, and dose buildup effect, respectively. Since an accuracy of 5% in the delivered dose is essential to prevent severe complications or tumor regrowth, the use of basic physical constants with uncertainties approaching 6% is unacceptable. A systematic evaluation of the pertinent radiation parameters contributes to a reduction in the overall uncertainty in HDR Ir-192 dose delivery. Moreover, the results of the studies described in this thesis contribute significantly to the establishment of standardized numerical values to be used in HDR Ir-192 dosimetry calculations.

Dosimetric systems of high dose, dose rate and dose uniformity in food and medical products

International Nuclear Information System (INIS)

Vargas, J.; Vivanco, M.; Castro, E.

2014-08-01

In the Instituto Peruano de Energia Nuclear (IPEN) we use the chemical dosimetry Astm-E-1026 Fricke as a standard dosimetric system of reference and different routine dosimetric systems of high doses, according to the applied doses to obtain the desired effects in the treated products and the doses range determined for each type of dosimeter. Fricke dosimetry is a chemical dosimeter in aqueous solution indicating the absorbed dose by means an increase in absorbance at a specific wavelength. A calibrated spectrophotometer with controlled temperature is used to measure absorbance. The adsorbed dose range should cover from 20 to 400 Gy, the Fricke solution is extremely sensitive to organic impurities, to traces of metal ions, in preparing chemical products of reactive grade must be used and the water purity is very important. Using the referential standard dosimetric system Fricke, was determined to March 5, 2013, using the referential standard dosimetric system Astm-1026 Fricke, were irradiated in triplicate Fricke dosimeters, to 5 irradiation times (20; 30; 40; 50 and 60 seconds) and by linear regression, the dose rate of 5.400648 kGy /h was determined in the central point of the irradiation chamber (irradiator Gamma cell 220 Excel), applying the decay formula, was compared with the obtained results by manufacturers by means the same dosimetric system in the year of its manufacture, being this to the date 5.44691 kGy /h, with an error rate of 0.85. After considering that the dosimetric solution responds to the results, we proceeded to the irradiation of a sample of 200 g of cereal instant food, 2 dosimeters were placed at the lateral ends of the central position to maximum dose and 2 dosimeters in upper and lower ends as minimum dose, they were applied same irradiation times; for statistical analysis, the maximum dose rate was 6.1006 kGy /h and the minimum dose rate of 5.2185 kGy /h; with a dose uniformity of 1.16. In medical material of micro pulverized bone for

Analysis of operators' surface doses in the common endovascular and on-vascular interventional diagnosis and treatment

International Nuclear Information System (INIS)

Zhang Lin; Zhu Jianguo; Min Nan; Lu Feng

2011-01-01

Objective: To contrast the level of radiation doses of Lead protective clothing both inside and outside in different parts of the body of the first and second operators and touring nurse in common endovascular and non-vascular interventional diagnosis and treatment. Methods: We choose the common endovascular interventional diagnosis and treatment in the head, thorax, abdomen, such as Cerebral angiography, Coronary angiography, Transcatheter arterial chemoembolization and non-vascular interventional diagnosis and treatment such as Endoscopic Retrograde Cholangio-Pancreatography and Percutaneous transhepatic cholangial drainage as experiment objects. Put the thermoluminescence dosimeter on the different spots of Lead protective clothing of subjects (Inside and outside the lead cap and the lead collar, inside and outside of the lead protective clothing in chest and abdomen, left upper arm outside of lead protective clothing, back of the left hand) and X-ray machine outgoing port when the operation was going on. After that, measure the thermoluminescence dosimeter, calculate and analyze exposure doses inside and outside of the lead protective clothing. Results: The skin doses of operators in different types of interventional diagnosis and treatment are listed in Table 1to Table 4; exposure doses of touring nurses are very low; the doses of X-ray machine outgoing port are mostly over the measuring range. Conclusion: The protection of Lead clothes plays a significant role in these two types of interventional diagnosis and treatment based on the conclusion that the dose of inside of Lead clothes is less than that of outside. We should enhance the operators' protection and administration in the process of intervention and arise the conscious of self-protection, to avoid the unnecessary radiation exposure. (authors)

Chromosomal Aberrations in Normal and AT Cells Exposed to High Dose of Low Dose Rate Irradiation

Science.gov (United States)

Kawata, T.; Shigematsu, N.; Kawaguchi, O.; Liu, C.; Furusawa, Y.; Hirayama, R.; George, K.; Cucinotta, F.

2011-01-01

Ataxia telangiectasia (A-T) is a human autosomally recessive syndrome characterized by cerebellar ataxia, telangiectases, immune dysfunction, and genomic instability, and high rate of cancer incidence. A-T cell lines are abnormally sensitive to agents that induce DNA double strand breaks, including ionizing radiation. The diverse clinical features in individuals affected by A-T and the complex cellular phenotypes are all linked to the functional inactivation of a single gene (AT mutated). It is well known that cells deficient in ATM show increased yields of both simple and complex chromosomal aberrations after high-dose-rate irradiation, but, less is known on how cells respond to low-dose-rate irradiation. It has been shown that AT cells contain a large number of unrejoined breaks after both low-dose-rate irradiation and high-dose-rate irradiation, however sensitivity for chromosomal aberrations at low-dose-rate are less often studied. To study how AT cells respond to low-dose-rate irradiation, we exposed confluent normal and AT fibroblast cells to up to 3 Gy of gamma-irradiation at a dose rate of 0.5 Gy/day and analyzed chromosomal aberrations in G0 using fusion PCC (Premature Chromosomal Condensation) technique. Giemsa staining showed that 1 Gy induces around 0.36 unrejoined fragments per cell in normal cells and around 1.35 fragments in AT cells, whereas 3Gy induces around 0.65 fragments in normal cells and around 3.3 fragments in AT cells. This result indicates that AT cells can rejoin breaks less effectively in G0 phase of the cell cycle? compared to normal cells. We also analyzed chromosomal exchanges in normal and AT cells after exposure to 3 Gy of low-dose-rate rays using a combination of G0 PCC and FISH techniques. Misrejoining was detected in the AT cells only? When cells irradiated with 3 Gy were subcultured and G2 chromosomal aberrations were analyzed using calyculin-A induced PCC technique, the yield of unrejoined breaks decreased in both normal and AT

Physiological and immunological changes following exposure to low versus high-dose ionizing irradiation; comparative analysis with dose rate and cumulative dose

International Nuclear Information System (INIS)

Heesun, Kim; Heewon, Jang; Soungyeon, Song; Shinhye, Oh; Cukcheul, Shin; Meeseon, Jeong; Chasoon, Kim; Kwnaghee, Yang; Seonyoung, Nam; Jiyoung, Kim; Youngwoo, Jin; Changyoung, Cha

2008-01-01

Full text: While high-dose of ionizing radiation is generally harmful and causes damage to living organisms some reports suggest low-dose of radiation may not be as damaging as previously thought. Despite increasing evidence regarding the protective effect of low-dose radiation, no studies have directly compared the exact dose-response pattern by high- and low-dose of radiation exposed at high-and low-dose rate. This study aims to explore the cellular and molecular changes in mice exposed to low- and high-dose of radiation exposed at low- and high-dose rate. When C57BL/6 mice (Female, 6 weeks) were exposed at high-dose rate, 0.8 Gy/min, no significant change on the level of WBC, RBC, or platelets was observed up to total dose of 0.5 Gy. However, 2 Gy of radiation caused dramatic reduction in the level of white blood cells (WBC) and platelets. This reduction was accompanied by increased DNA damage in hematopoietic environments. The reduction of WBC was mainly due to the reduction in the number of CD4+ T cells and CD19+ B cells. CD8+ T cells and NK cells appeared to be relatively resistant to high-dose of radiation. This change was also accompanied by the reduction of T- and B- progenitor cells in the bone marrow. In contrast, no significant changes of the number of CD4+ T, CD8+ T, NK, and B cells were observed in the spleen of mice exposed at low-dose-rate (0.7 m Gy/h or 3.95 mGy/h) for up to 2 Gy, suggesting that low-dose radiation does not alter cellular distribution in the spleen. Nevertheless, mice exposed to low-dose radiation exhibited elevation of VEGF, MCP-1, IL-4, Leptin, IL-3, and Tpo in the peripheral blood and slight increases in MIP-2, RANTES, and IL-2 in the spleen. This suggests that chronic γ-radiation can stimulate immune function without causing damage to the immune components of the body. Taken together, these data indicate hormesis of low-dose radiation, which could be attributed to the stimulation of immune function. Dose rate rather than total

High dose rate versus low dose rate interstitial radiotherapy for carcinoma of the floor of mouth

International Nuclear Information System (INIS)

Inoue, Takehiro; Inoue, Toshihiko; Yamazaki, Hideya; Koizumi, Masahiko; Kagawa, Kazufumi; Yoshida, Ken; Shiomi, Hiroya; Imai, Atsushi; Shimizutani, Kimishige; Tanaka, Eichii; Nose, Takayuki; Teshima, Teruki; Furukawa, Souhei; Fuchihata, Hajime

1998-01-01

Purpose: Patients with cancer of the floor of mouth are treated with radiation because of functional and cosmetic reasons. We evaluate the treatment results of high dose rate (HDR) and low dose rate (LDR) interstitial radiation for cancer of the floor of mouth. Methods and Materials: From January 1980 through March 1996, 41 patients with cancer of the floor of mouth were treated with LDR interstitial radiation using 198 Au grains, and from April 1992 through March 1996 16 patients with HDR interstitial radiation. There were 26 T1 tumors, 30 T2 tumors, and 1 T3 tumor. For 21 patients treated with interstitial radiation alone, a total radiation dose of interstitial therapy was 60 Gy/10 fractions/6-7 days in HDR and 85 Gy within 1 week in LDR. For 36 patients treated with a combination therapy, a total dose of 30 to 40 Gy of external radiation and a total dose of 48 Gy/8 fractions/5-6 days in HDR or 65 Gy within 1 week in LDR were delivered. Results: Two- and 5-year local control rates of patients treated with HDR interstitial radiation were 94% and 94%, and those with LDR were 75% and 69%, respectively. Local control rate of patients treated with HDR brachytherapy was slightly higher than that with 198 Au grains (p = 0.113). For late complication, bone exposure or ulcer occurred in 6 of 16 (38%) patients treated with HDR and 13 of 41 (32%) patients treated with LDR. Conclusion: HDR fractionated interstitial brachytherapy can be an alternative to LDR brachytherapy for cancer of the floor of mouth and eliminate radiation exposure for the medical staff

A comparison of anti-tumor effects of high dose rate fractionated and low dose rate continuous irradiation in multicellular spheroids

International Nuclear Information System (INIS)

Kubota, Nobuo; Omura, Motoko; Matsubara, Sho.

1997-01-01

In a clinical experience, high dose rate (HDR) fractionated interstitial radiotherapy can be an alternative to traditional low dose rate (LDR) continuous interstitial radiotherapy for head and neck cancers. To investigate biological effect of HDR, compared to LDR, comparisons have been made using spheroids of human squamous carcinoma cells. Both LDR and HDR were delivered by 137 Cs at 37degC. Dose rate of LDR was 8 Gy/day and HDR irradiations of fraction size of 4, 5 or 6 Gy were applied twice a day with an interval time of more than 6 hr. We estimated HDR fractionated dose of 31 Gy with 4 Gy/fr to give the same biological effects of 38 Gy by continuous LDR for spheroids. The ratio of HDR/LDR doses to control 50% spheroids was 0.82. (author)

HIGH-DOSE RATE BRACHYTHERAPY IN CARCINOMA CERVIX STAGE IIIB

Directory of Open Access Journals (Sweden)

Sathya Maruthavanan

2016-07-01

Full Text Available INTRODUCTION Radiotherapy is the standard treatment in locally advanced (IIB-IVA and early inoperable cases. The current standard of practice with curable intent is concurrent chemoradiation in which intracavitary brachytherapy is an integral component of radiotherapy. This study aims at assessing the efficacy of HDR ICBT (High-dose rate intracavitary brachytherapy in terms local response, normal tissue reactions, and feasibility. METHODS AND MATERIALS A total of 20 patients of stage IIIB cancer of the uterine cervix were enrolled in the study and were planned to receive concurrent chemotherapy weekly along with EBRT (external beam radiotherapy to a dose of 50 Gy/25 Fr. Suitability for ICBT was assessed at 40 Gy/20 Fr. 6/20 patients were suitable at 40 Gy and received HDR ICBT with a dose of 5.5 Gy to point A in 4 sessions (5.5 Gy/4 Fr. The remaining 14/20 patients completed 50 Gy and received HDR ICBT with a dose of 6 Gy to point A in 3 sessions (6 Gy/3 Fr. RESULTS A total of 66 intracavitary applications were done and only one application required dose modification due to high bladder dose, the pelvic control rate was 85% (17/20. 10% (2/20 had stable disease and 5% (1/20 had progressive disease at one year of follow up. When toxicity was considered only 15% developed grade I and grade II rectal complications. Patient compliance and acceptability was 100%. Patients were very comfortable with the short treatment time as compared with patients on LDR ICBT (low-dose rate intracavitary brachytherapy treatment interviewed during the same period. CONCLUSION This study proves that HDR brachytherapy is efficacious and feasible in carcinoma of cervix stage IIIB. It also proves that good dose distribution can be achieved with HDR intracavitary facility by the use of dose optimization. The short treatment time in HDR ICBT makes it possible to maintain this optimised dose distribution throughout the treatment providing a gain in the therapeutic ratio and

Pulsed dose rate and fractionated high dose rate brachytherapy: choice of brachytherapy schedules to replace low dose rate treatments

International Nuclear Information System (INIS)

Visser, Andries G.; Aardweg, Gerard J.M.J. van den; Levendag, Peter C.

1996-01-01

Purpose: Pulsed dose rate (PDR) brachytherapy is a new type of afterloading brachytherapy (BT) in which a continuous low dose rate (LDR) treatment is simulated by a series of 'pulses,' i.e., fractions of short duration (less than 0.5 h) with intervals between fractions of 1 to a few hours. At the Dr. Daniel den Hoed Cancer Center, the term 'PDR brachytherapy' is used for treatment schedules with a large number of fractions (at least four per day), while the term 'fractionated high dose rate (HDR) brachytherapy' is used for treatment schedules with just one or two brachytherapy fractions per day. Both treatments can be applied as alternatives for LDR BT. This article deals with the choice between PDR and fractionated HDR schedules and proposes possible fractionation schedules. Methods and Materials: To calculate HDR and PDR fractionation schedules with the intention of being equivalent to LDR BT, the linear-quadratic (LQ) model has been used in an incomplete repair formulation as given by Brenner and Hall, and by Thames. In contrast to earlier applications of this model, both the total physical dose and the overall time were not kept identical for LDR and HDR/PDR schedules. A range of possible PDR treatment schedules is presented, both for booster applications (in combination with external radiotherapy (ERT) and for BT applications as a single treatment. Because the knowledge of both α/β values and the half time for repair of sublethal damage (T (1(2)) ), which are required for these calculations, is quite limited, calculations regarding the equivalence of LDR and PDR treatments have been performed for a wide range of values of α/β and T (1(2)) . The results are presented graphically as PDR/LDR dose ratios and as ratios of the PDR/LDR tumor control probabilities. Results: If the condition that total physical dose and overall time of a PDR treatment must be exactly identical to the values for the corresponding LDR treatment regimen is not applied, there appears

Treatment of carcinoma of uterine cervix with high-dose-rate intracavitary irradiation using Ralstron

International Nuclear Information System (INIS)

Suh, C.O.; Kim, G.E.; Loh, J.J.K.

1988-01-01

From May 1979 through December 1981, a total of 530 patients with carcinoma of the uterine cervix were treated with radiation therapy with curative intent. Of the 530 patients, 365 were treated with a high-dose-rate remote-controlled afterloading system (RALS) using a cobalt source, and 165 patients received a low dose rate using a radium source. External pelvic irradiation with a total of 40-50 Gy to the whole pelvis followed by intracavitary radiation (ICR) with a total dose of 30-39 Gy in ten to 13 fractions to point A was the treatment protocol. ICR was given three times a week with a dose of 3 Gy per fraction. Five-year actuarial survival rate with high-dose-rate ICR by stage was as follows: stage I:82.7% (N = 19) stage II:69.6% (N = 184), and stage III:52.2% (N = 156). The above results were comparable with those with conventional low-dose-rate ICR treatment, and late complications were far less. The application of high-dose-rate ICR was technically simple and easily performed on an outpatient basis without anesthesia, and the patients tolerated it very well. Radiation exposure to personnel was virtually none as compared with that of low-dose-rate ICR. Within a given period of time, more patients can be treated with high-dose-rate ICR because of the short treatment time. The authors therefore conclude that high-dose-rate ICR is suitable for a cancer center where a large number of patients are to be treated

Efficacy of a radiation absorbing shield in reducing dose to the interventionalist during peripheral endovascular procedures: a single centre pilot study.

Science.gov (United States)

Power, S; Mirza, M; Thakorlal, A; Ganai, B; Gavagan, L D; Given, M F; Lee, M J

2015-06-01

This prospective pilot study was undertaken to evaluate the feasibility and effectiveness of using a radiation absorbing shield to reduce operator dose from scatter during lower limb endovascular procedures. A commercially available bismuth shield system (RADPAD) was used. Sixty consecutive patients undergoing lower limb angioplasty were included. Thirty procedures were performed without the RADPAD (control group) and thirty with the RADPAD (study group). Two separate methods were used to measure dose to a single operator. Thermoluminescent dosimeter (TLD) badges were used to measure hand, eye, and unshielded body dose. A direct dosimeter with digital readout was also used to measure eye and unshielded body dose. To allow for variation between control and study groups, dose per unit time was calculated. TLD results demonstrated a significant reduction in median body dose per unit time for the study group compared with controls (p = 0.001), corresponding to a mean dose reduction rate of 65 %. Median eye and hand dose per unit time were also reduced in the study group compared with control group, however, this was not statistically significant (p = 0.081 for eye, p = 0.628 for hand). Direct dosimeter readings also showed statistically significant reduction in median unshielded body dose rate for the study group compared with controls (p = 0.037). Eye dose rate was reduced for the study group but this was not statistically significant (p = 0.142). Initial results are encouraging. Use of the shield resulted in a statistically significant reduction in unshielded dose to the operator's body. Measured dose to the eye and hand of operator were also reduced but did not reach statistical significance in this pilot study.

Standardization of high-dose measurement of electron and gamma ray absorbed doses and dose rates

International Nuclear Information System (INIS)

McLaughlin, W.L.

1985-01-01

Intense electron beams and gamma radiation fields are used for sterilizing medical devices, treating municipal wastes, processing industrial goods, controlling parasites and pathogens, and extending the shelf-life of foods. Quality control of such radiation processes depends largely on maintaining measurement quality assurance through sound dosimetry procedures in the research leading to each process, in the commissioning of that process, and in the routine dose monitoring practices. This affords documentation as to whether satisfactory dose uniformity is maintained throughout the product and throughout the process. Therefore, dosimetry at high doses and dose rates must in many radiation processes be standardized carefully, so that 'dosimetry release' of a product is verified. This standardization is initiated through preliminary dosimetry intercomparison studies such as those sponsored recently by the IAEA. This is followed by establishing periodic exercises in traceability to national or international standards of absorbed dose and dose rate. Traceability is achieved by careful selection of dosimetry methods and proven reference dosimeters capable of giving sufficiently accurate and precise 'transfer' dose assessments: (1) they must be calibrated or have well-established radiation-yield indices; (2) their radiation response characteristics must be reproducible and cover the dose range of interest; (3) they must withstand the rigours of back-and-forth mailing between a central standardizing laboratory and radiation processing facilities, without excessive errors arising due to instabilities, dosimeter batch non-uniformities, and environmental and handling stresses. (author)

Dose volume assessment of high dose rate 192IR endobronchial implants

International Nuclear Information System (INIS)

Cheng, B. Saw; Korb, Leroy J.; Pawlicki, Todd; Wu, Andrew

1996-01-01

Purpose: To study the dose distributions of high dose rate (HDR) endobronchial implants using the dose nonuniformity ratio (DNR) and three volumetric irradiation indices. Methods and Materials: Multiple implants were configured by allowing a single HDR 192 Ir source to step through a length of 6 cm along an endobronchial catheter. Dwell times were computed to deliver a dose of 5 Gy to points 1 cm away from the catheter axis. Five sets of source configurations, each with different dwell position spacings from 0.5 to 3.0 cm, were evaluated. Three-dimensional (3D) dose distributions were then generated for each source configuration. Differential and cumulative dose-volume curves were generated to quantify the degree of target volume coverage, dose nonuniformity within the target volume, and irradiation of tissues outside the target volume. Evaluation of the implants were made using the DNR and three volumetric irradiation indices. Results: The observed isodose distributions were not able to satisfy all the dose constraints. The ability to optimally satisfy the dose constraints depended on the choice of dwell position spacing and the specification of the dose constraint points. The DNR and irradiation indices suggest that small dwell position spacing does not result in a more homogeneous dose distribution for the implant. This study supports the existence of a relationship between the dwell position spacing and the distance from the catheter axis to the reference dose or dose constraint points. Better dose homogeneity for an implant can be obtained if the spacing of the dwell positions are about twice the distance from the catheter axis to the reference dose or dose constraint points

Actual review of diagnostics and endovascular therapy of intracranial arterial stenoses

International Nuclear Information System (INIS)

Gizewski, E.R.; Weber, R.; Forsting, M.

2011-01-01

Approximately 6 - 50 % of all ischemic strokes are caused by intracranial arterial stenosis (IAS). Despite medical prevention, patients with symptomatic IAS have a high annual risk for recurrent ischemic stroke of about 12 %, and up to 19 % in the case of high-grade IAS (≥ 70 %). Digital subtraction angiography remains the gold standard for the diagnosis and grading of IAS. However, noninvasive imaging techniques including CT angiography, MR angiography, or transcranial Doppler and duplex ultrasound examinations are used in the clinical routine to provide additional information about the brain structure and hemodynamic. However, for technical reasons, the grading of stenoses is sometimes difficult and inaccurate. To date, aspirin is recommended as the treatment of choice in the prevention of recurrent ischemic stroke in patients with IAS. IAS patients who suffer a recurrent ischemic stroke or transient ischemic attack while taking aspirin can be treated with endovascular stenting or angioplasty in specialized centers. The periprocedural complication rate of these endovascular techniques is about 2 - 7 % at experienced neuro-interventional centers. The rate of re-stenosis is reported between 10 and 40 % depending on patient age and stenosis location. Further randomized studies comparing medical secondary prevention and endovascular therapy are currently being performed. With regard to the improvement of endovascular methods and lower complication rates, the indication for endovascular therapy in IAS could be broadened especially for stenosis in the posterior circulation. (orig.)

Efficacy of a Radiation Absorbing Shield in Reducing Dose to the Interventionalist During Peripheral Endovascular Procedures: A Single Centre Pilot Study

International Nuclear Information System (INIS)

Power, S.; Mirza, M.; Thakorlal, A.; Ganai, B.; Gavagan, L. D.; Given, M. F.; Lee, M. J.

2015-01-01

PurposeThis prospective pilot study was undertaken to evaluate the feasibility and effectiveness of using a radiation absorbing shield to reduce operator dose from scatter during lower limb endovascular procedures.Materials and MethodsA commercially available bismuth shield system (RADPAD) was used. Sixty consecutive patients undergoing lower limb angioplasty were included. Thirty procedures were performed without the RADPAD (control group) and thirty with the RADPAD (study group). Two separate methods were used to measure dose to a single operator. Thermoluminescent dosimeter (TLD) badges were used to measure hand, eye, and unshielded body dose. A direct dosimeter with digital readout was also used to measure eye and unshielded body dose. To allow for variation between control and study groups, dose per unit time was calculated.ResultsTLD results demonstrated a significant reduction in median body dose per unit time for the study group compared with controls (p = 0.001), corresponding to a mean dose reduction rate of 65 %. Median eye and hand dose per unit time were also reduced in the study group compared with control group, however, this was not statistically significant (p = 0.081 for eye, p = 0.628 for hand). Direct dosimeter readings also showed statistically significant reduction in median unshielded body dose rate for the study group compared with controls (p = 0.037). Eye dose rate was reduced for the study group but this was not statistically significant (p = 0.142).ConclusionInitial results are encouraging. Use of the shield resulted in a statistically significant reduction in unshielded dose to the operator’s body. Measured dose to the eye and hand of operator were also reduced but did not reach statistical significance in this pilot study

Efficacy of a Radiation Absorbing Shield in Reducing Dose to the Interventionalist During Peripheral Endovascular Procedures: A Single Centre Pilot Study

Energy Technology Data Exchange (ETDEWEB)

Power, S.; Mirza, M.; Thakorlal, A.; Ganai, B.; Gavagan, L. D.; Given, M. F.; Lee, M. J., E-mail: mlee@rcsi.ie [Beaumont Hospital, Imaging and Interventional Radiology Department (Ireland)

2015-06-15

PurposeThis prospective pilot study was undertaken to evaluate the feasibility and effectiveness of using a radiation absorbing shield to reduce operator dose from scatter during lower limb endovascular procedures.Materials and MethodsA commercially available bismuth shield system (RADPAD) was used. Sixty consecutive patients undergoing lower limb angioplasty were included. Thirty procedures were performed without the RADPAD (control group) and thirty with the RADPAD (study group). Two separate methods were used to measure dose to a single operator. Thermoluminescent dosimeter (TLD) badges were used to measure hand, eye, and unshielded body dose. A direct dosimeter with digital readout was also used to measure eye and unshielded body dose. To allow for variation between control and study groups, dose per unit time was calculated.ResultsTLD results demonstrated a significant reduction in median body dose per unit time for the study group compared with controls (p = 0.001), corresponding to a mean dose reduction rate of 65 %. Median eye and hand dose per unit time were also reduced in the study group compared with control group, however, this was not statistically significant (p = 0.081 for eye, p = 0.628 for hand). Direct dosimeter readings also showed statistically significant reduction in median unshielded body dose rate for the study group compared with controls (p = 0.037). Eye dose rate was reduced for the study group but this was not statistically significant (p = 0.142).ConclusionInitial results are encouraging. Use of the shield resulted in a statistically significant reduction in unshielded dose to the operator’s body. Measured dose to the eye and hand of operator were also reduced but did not reach statistical significance in this pilot study.

High dose rate endobronchial brachytherapy - treatment technique

International Nuclear Information System (INIS)

Carvalho, Heloisa de Andrade; Aisen, Salim; Haddad, Cecilia Maria Kalil; Nadalin, Wladimir; Pedreira Junior, Wilson Leite; Chavantes, Maria Cristina

1998-01-01

High dose rate endobronchial brachytherapy is efficient in symptom relief due to obstructive endobronchial malignancies. However, it's role in survival improvement for patients with lung cancer is not yet established. The use of this treatment in increasing, specially in the developing countries. The purpose of this paper is to present the treatment technique used in the Radiotherapy Department of the Hospital da Clinicas, University of Sao Paulo, based on an experience of 60 cases treated with 180 procedures. Some practical suggestions and rules adopted in the Department are described. The severe complications rate is 6.7%, demonstrating an adequate patient selection associated with the technique utilized. (author)

The optimal fraction size in high-dose-rate brachytherapy: dependency on tissue repair kinetics and low-dose rate

International Nuclear Information System (INIS)

Sminia, Peter; Schneider, Christoph J.; Fowler, Jack F.

2002-01-01

Background and Purpose: Indications of the existence of long repair half-times on the order of 2-4 h for late-responding human normal tissues have been obtained from continuous hyperfractionated accelerated radiotherapy (CHART). Recently, these data were used to explain, on the basis of the biologically effective dose (BED), the potential superiority of fractionated high-dose rate (HDR) with large fraction sizes of 5-7 Gy over continuous low-dose rate (LDR) irradiation at 0.5 Gy/h in cervical carcinoma. We investigated the optimal fraction size in HDR brachytherapy and its dependency on treatment choices (overall treatment time, number of HDR fractions, and time interval between fractions) and treatment conditions (reference low-dose rate, tissue repair characteristics). Methods and Materials: Radiobiologic model calculations were performed using the linear-quadratic model for incomplete mono-exponential repair. An irradiation dose of 20 Gy was assumed to be applied either with HDR in 2-12 fractions or continuously with LDR for a range of dose rates. HDR and LDR treatment regimens were compared on the basis of the BED and BED ratio of normal tissue and tumor, assuming repair half-times between 1 h and 4 h. Results: With the assumption that the repair half-time of normal tissue was three times longer than that of the tumor, hypofractionation in HDR relative to LDR could result in relative normal tissue sparing if the optimum fraction size is selected. By dose reduction while keeping the tumor BED constant, absolute normal tissue sparing might therefore be achieved. This optimum HDR fraction size was found to be largely dependent on the LDR dose rate. On the basis of the BED NT/TUM ratio of HDR over LDR, 3 x 6.7 Gy would be the optimal HDR fractionation scheme for replacement of an LDR scheme of 20 Gy in 10-30 h (dose rate 2-0.67 Gy/h), while at a lower dose rate of 0.5 Gy/h, four fractions of 5 Gy would be preferential, still assuming large differences between tumor

Comparison of high-dose-rate and low-dose-rate brachytherapy in the treatment of endometrial carcinoma

International Nuclear Information System (INIS)

Fayed, Alaa; Mutch, David G.; Rader, Janet S.; Gibb, Randall K.; Powell, Matthew A.; Wright, Jason D.; El Naqa, Issam; Zoberi, Imran; Grigsby, Perry W.

2007-01-01

Purpose: To compare the outcomes for endometrial carcinoma patients treated with either high-dose-rate (HDR) or low-dose-rate (LDR) brachytherapy. Methods and Materials: This study included 1,179 patients divided into LDR (1,004) and HDR groups (175). Patients with International Federation of Gynecology and Obstetrics (FIGO) surgical Stages I-III were included. All patients were treated with postoperative irradiation. In the LDR group, the postoperative dose applied to the vaginal cuff was 60-70 Gy surface doses to the vaginal mucosa. The HDR brachytherapy prescription was 6 fractions of 2 Gy each to a depth of 0.5 cm from the surface of the vaginal mucosa. Overall survival, disease-free survival, local control, and complications were endpoints. Results: For all stages combined, the overall survival, disease-free survival, and local control at 5 years in the LDR group were 70%, 69%, and 81%, respectively. For all stages combined, the overall survival, disease-free survival, and local control at 5 years in the HDR group were 68%, 62%, and 78%, respectively. There were no significant differences in early or late Grade III and IV complications in the HDR or LDR groups. Conclusion: Survival outcomes, pelvic tumor control, and Grade III and IV complications were not significantly different in the LDR brachytherapy group compared with the HDR group

Retrospective analysis of dose delivery in intra-operative high dose rate brachytherapy

International Nuclear Information System (INIS)

Oh, M.; Avadhani, J.S.; Malhotra, H.K.; Cunningham, B.; Tripp, P.; Jaggernauth, W.; Podgorsak, M.B.

2007-01-01

Background. This study was performed to quantify the inaccuracy in clinical dose delivery due to the incomplete scatter conditions inherent in intra-operative high dose rate (IOHDR) brachytherapy. Methods. Treatment plans of 10 patients previously treated in our facility, which had irregular shapes of treated areas, were used. Treatment geometries reflecting each clinical case were simulated using a phantom assembly with no added build-up on top of the applicator. The treatment planning geometry (full scatter surrounding the applicator) was subsequently simulated for each case by adding bolus on top of the applicator. Results. For geometries representing the clinical IOHDR incomplete scatter environment, measured doses at the 5 mm and 10 mm prescription depths were lower than the corresponding prescribed doses by about 7.7% and 11.1%, respectively. Also, for the two prescription methods, an analysis of the measured dose distributions and their corresponding treatment plans showed average decreases of 1.2 mm and 2.2 mm in depth of prescription dose, respectively. Conclusions. Dosimetric calculations with the assumption of an infinite scatter environment around the applicator and target volume have shown to result in dose delivery errors that significantly decrease the prescription depth for IOHDR treatment.(author)

Image-Guided Stereotactic Radiosurgery Using a Specially Designed High-Dose-Rate Linac

International Nuclear Information System (INIS)

Bayouth, John E.; Kaiser, Heather S.; Smith, Mark C.; Pennington, Edward C.; Anderson, Kathleen M. C.; Ryken, Timothy C.; Buatti, John M.

2007-01-01

Stereotactic radiosurgery and image-guided radiotherapy (IGRT) place enhanced demands on treatment delivery machines. In this study, we describe a high-dose-rate output accelerator as a part of our stereotactic IGRT delivery system. The linac is a Siemens Oncor without a flattening filter, and enables dose rates to reach 1000 monitor units (MUs) per minute. Even at this high-dose-rate, the linac dosimetry system remains robust; constancy, linearity, and beam energy remain within 1% for 3 to 1000 MU. Dose profiles for larger field sizes are not flat, but they are radially symmetric and, as such, able to be modeled by a treatment planning system. Target localization is performed via optical guidance utilizing a 3-dimensional (3D) ultrasound probe coupled to an array of 4 infrared light-emitting diodes. These diodes are identified by a fixed infrared camera system that determines diode position and, by extension, all objects imaged in the room coordinate system. This system provides sub-millimeter localization accuracy for cranial applications and better than 1.5 mm for extracranial applications. Because stereotactic IGRT can require significantly longer times for treatment delivery, the advantages of the high-dose-rate design and its direct impact on IGRT are discussed

Gynecological brachytherapy - from low-dose-rate to high-tech. Gynaekologische Brachytherapie - von Low-dose-rate zu High-tech

Energy Technology Data Exchange (ETDEWEB)

Herrmann, T. (Abt. Strahlenthgerapie, Klinik und Poliklinik fuer Radiologie, Medizinische Akademie ' Carl Gustav Carus' , Dresden (Germany)); Christen, N. (Abt. Strahlenthgerapie, Klinik und Poliklinik fuer Radiologie, Medizinische Akademie ' Carl Gustav Carus' , Dresden (Germany)); Alheit, H.D. (Abt. Strahlenthgerapie, Klinik und Poliklinik fuer Radiologie, Medizinische Akademie ' Carl Gustav Carus' , Dresden (Germany))

1993-03-01

The transition from low-dose-rate (LDR) brachytherapy to high-dose-rate (HDR) afterloading treatment is in progress in most centres of radiation therapy. First reports of studies comparing HDR and LDR treatment in cervix cancer demonstrate nearly equal local control. In our own investigations on 319 patients with primary irradiated carcinoma of the cervix (125 HDR/194 LDR) we found the following control rates: Stage FIGO I 95.4%/82.9% (HDR versus LDR), stage FIGO II 71.4%/73.7%, stage FIGO III 57.9%/38.5%. The results are not significant. The side effects - scored after EORT/RTOG criteria - showed no significant differences between both therapies for serious radiogenic late effects on intestine, bladder and vagina. The study and findings from the literature confirm the advantage of the HDR-procedure for patient and radiooncologist and for radiation protection showing at least the same results as in the LDR-area. As for radiobiolgical point of view it is important to consider that the use of fractionation in the HDR-treatment is essential for the sparing of normal tissues and therefore a greater number of small fractionation doses in the brachytherapy should be desirable too. On the other hand the rules, which are true for fractionated percutaneous irradiation therapy (overall treatment time as short as possible to avoid reppopulation of tumor cells) should be taken into consideration in combined brachy-teletherapy regime in gynecologic tumors. The first step in this direction may be accelerated regime with a daily application of both treatment procedures. The central blocking of the brachytherapy region from the whole percutaneous treatment target volume should be critically reflected, especially in the case of advanced tumors. (orig.)

Developing A Directional High-Dose Rate (d-HDR) Brachytherapy Source

Science.gov (United States)

Heredia, Athena Yvonne

Conventional sources used in brachytherapy provide nearly isotropic or radially symmetric dose distributions. Optimizations of dose distributions have been limited to varied dwell times at specified locations within a given treatment volume, or manipulations in source position for seed implantation techniques. In years past, intensity modulated brachytherapy (IMBT) has been used to reduce the amount of radiation to surrounding sensitive structures in select intracavitary cases by adding space or partial shields. Previous work done by Lin et al., at the University of Wisconsin-Madison, has shown potential improvements in conformality for brachytherapy treatments using a directionally shielded low dose rate (LDR) source for treatments in breast and prostate. Directional brachytherapy sources irradiate approximately half of the radial angles around the source, and adequately shield a quarter of the radial angles on the opposite side, with sharp gradient zones between the treated half and shielded quarter. With internally shielded sources, the radiation can be preferentially emitted in such a way as to reduce toxicities in surrounding critical organs. The objective of this work is to present findings obtained in the development of a new directional high dose rate (d-HDR) source. To this goal, 103Pd (Z = 46) is reintroduced as a potential radionuclide for use in HDR brachytherapy. 103Pd has a low average photon energy (21 keV) and relatively short half -life (17 days), which is why it has historically been used in low dose rate applications and implantation techniques. Pd-103 has a carrier-free specific activity of 75000 Ci/g. Using cyclotron produced 103Pd, near carrier-free specific activities can be achieved, providing suitability for high dose rate applications. The evolution of the d-HDR source using Monte Carlo simulations is presented, along with dosimetric parameters used to fully characterize the source. In addition, a discussion on how to obtain elemental

High and low dose-rate brachytherapy for cervical carcinoma

International Nuclear Information System (INIS)

Orton, C.G.

1998-01-01

For the brachytherapy component of the r[iation treatment of cervical carcinoma, high dose rate (HDR) is slowly replacing conventional low dose rate (LDR) due primarily to r[iation safety and other physical benefits attributed to the HDR modality. Many r[iation oncologists are reluctant to make this change because of perceived r[iobiological dis[vantages of HDR. However, in clinical practice HDR appears to be as effective as LDR but with a lower risk of late complications, as demonstrated by one randomized clinical trial and two comprehensive literature and practice surveys. The reason for this appears to be that the r[iobiological dis[vantages of HDR are outweighed by the physical [vantages. (orig.)

Cost minimization analysis of high-dose-rate versus low-dose-rate brachytherapy in endometrial cancer

International Nuclear Information System (INIS)

Pinilla, James

1998-01-01

Purpose: Endometrial cancer is a common, usually curable malignancy whose treatment frequently involves low-dose-rate (LDR) or high-dose-rate (HDR) brachytherapy. These treatments involve substantial resource commitments and this is increasingly important. This paper presents a cost minimization analysis of HDR versus LDR brachytherapy in the treatment of endometrial cancer. Methods and Materials: The perspective of the analysis is that of the payor, in this case the Ministry of Health. One course of LDR treatment is compared to two courses of HDR treatment. The two alternatives are considered to be comparable with respect to local control, survival, and toxicities. Labor, overhead, and capital costs are accounted for and carefully measured. A 5% inflation rate is used where applicable. A univariate sensitivity analysis is performed. Results: The HDR regime is 22% less expensive compared to the LDR regime. This is $991.66 per patient or, based on the current workload of this department (30 patients per year) over the useful lifetime of the after loader, $297,498 over 10 years in 1997 dollars. Conclusion: HDR brachytherapy minimizes costs in the treatment of endometrial cancer relative to LDR brachytherapy. These results may be used by other centers to make rational decisions regarding brachytherapy equipment replacement or acquisition

Endovascular management of acute bleeding arterioenteric fistulas

DEFF Research Database (Denmark)

Leonhardt, H.; Mellander, S.; Snygg, J.

2008-01-01

follow-up time was 3 months (range, 1-6 months). All massive bleeding was controlled by occlusive balloon catheters. Four fistulas were successfully sealed with stent-grafts, resulting in a technical success rate of 80%. One patient was circulatory stabilized by endovascular management but needed....... All had massive persistent bleeding with hypotension despite volume substitution and transfusion by the time of endovascular management. Outcome after treatment of these patients was investigated for major procedure-related complications, recurrence, reintervention, morbidity, and mortality. Mean...... arterioenteric fistulas in the emergent episode. However, in this group of patients with severe comorbidities, the risk of rebleeding is high and further intervention must be considered. Patients with cancer may only need treatment for the acute bleeding episode, and an endovascular approach has the advantage...

Bayesian estimation of dose rate effectiveness

International Nuclear Information System (INIS)

Arnish, J.J.; Groer, P.G.

2000-01-01

A Bayesian statistical method was used to quantify the effectiveness of high dose rate 137 Cs gamma radiation at inducing fatal mammary tumours and increasing the overall mortality rate in BALB/c female mice. The Bayesian approach considers both the temporal and dose dependence of radiation carcinogenesis and total mortality. This paper provides the first direct estimation of dose rate effectiveness using Bayesian statistics. This statistical approach provides a quantitative description of the uncertainty of the factor characterising the dose rate in terms of a probability density function. The results show that a fixed dose from 137 Cs gamma radiation delivered at a high dose rate is more effective at inducing fatal mammary tumours and increasing the overall mortality rate in BALB/c female mice than the same dose delivered at a low dose rate. (author)

High dose-per-pulse electron beam dosimetry: Usability and dose-rate independence of EBT3 Gafchromic films.

Science.gov (United States)

Jaccard, Maud; Petersson, Kristoffer; Buchillier, Thierry; Germond, Jean-François; Durán, Maria Teresa; Vozenin, Marie-Catherine; Bourhis, Jean; Bochud, François O; Bailat, Claude

2017-02-01

The aim of this study was to assess the suitability of Gafchromic EBT3 films for reference dose measurements in the beam of a prototype high dose-per-pulse linear accelerator (linac), capable of delivering electron beams with a mean dose-rate (Ḋ m ) ranging from 0.07 to 3000 Gy/s and a dose-rate in pulse (Ḋ p ) of up to 8 × 10 6 Gy/s. To do this, we evaluated the overall uncertainties in EBT3 film dosimetry as well as the energy and dose-rate dependence of their response. Our dosimetric system was composed of EBT3 Gafchromic films in combination with a flatbed scanner and was calibrated against an ionization chamber traceable to primary standard. All sources of uncertainties in EBT3 dosimetry were carefully analyzed using irradiations at a clinical radiotherapy linac. Energy dependence was investigated with the same machine by acquiring and comparing calibration curves for three different beam energies (4, 8 and 12 MeV), for doses between 0.25 and 30 Gy. Ḋ m dependence was studied at the clinical linac by changing the pulse repetition frequency (f) of the beam in order to vary Ḋ m between 0.55 and 4.40 Gy/min, while Ḋ p dependence was probed at the prototype machine for Ḋ p ranging from 7 × 10 3 to 8 × 10 6 Gy/s. Ḋ p dependence was first determined by studying the correlation between the dose measured by films and the charge of electrons measured at the exit of the machine by an induction torus. Furthermore, we compared doses from the films to independently calibrated thermo-luminescent dosimeters (TLD) that have been reported as being dose-rate independent up to such high dose-rates. We report that uncertainty below 4% (k = 2) can be achieved in the dose range between 3 and 17 Gy. Results also demonstrated that EBT3 films did not display any detectable energy dependence for electron beam energies between 4 and 12 MeV. No Ḋ m dependence was found either. In addition, we obtained excellent consistency between films and TLDs over the entire Ḋ p

Impact of catheter reconstruction error on dose distribution in high dose rate intracavitary brachytherapy and evaluation of OAR doses

International Nuclear Information System (INIS)

Thaper, Deepak; Shukla, Arvind; Rathore, Narendra; Oinam, Arun S.

2016-01-01

In high dose rate brachytherapy (HDR-B), current catheter reconstruction protocols are relatively slow and error prone. The purpose of this study is to evaluate the impact of catheter reconstruction error on dose distribution in CT based intracavitary brachytherapy planning and evaluation of its effect on organ at risk (OAR) like bladder, rectum and sigmoid and target volume High risk clinical target volume (HR-CTV)

Calibration procedure for thermoluminescent dosemeters in water absorbed doses for Iridium-192 high dose rate sources

International Nuclear Information System (INIS)

Reyes Cac, Franky Eduardo

2004-10-01

Thermoluminescent dosimeters are used in brachytherapy services quality assurance programs, with the aim of guaranteeing the correct radiation dose supplied to cancer patients, as well as with the purpose of evaluating new clinical procedures. This work describes a methodology for thermoluminescent dosimeters calibration in terms of absorbed dose to water for 192 Ir high dose rate sources. The reference dose used is measured with an ionization chamber previously calibrated for 192 Ir energy quality, applying the methodology proposed by Toelli. This methodology aims to standardizing the procedure, in a similar form to that used for external radiotherapy. The work evolves the adaptation of the TRS-277 Code of the International Atomic Energy Agency, for small and big cavities, through the introduction for non-uniform experimental factor, for the absorbed dose in the neighborhood of small brachytherapy sources. In order to simulate a water medium around the source during the experimental work, an acrylic phantom was used. It guarantees the reproducibility of the ionization chamber and the thermoluminescent dosimeter's location in relation to the radiation source. The values obtained with the ionization chamber and the thermoluminescent dosimeters, exposed to a 192 Ir high dose rate source, were compared and correction factors for different source-detector distances were determined for the thermoluminescent dosimeters. A numeric function was generated relating the correction factors and the source-detector distance. These correction factors are in fact the thermoluminescent dosimeter calibration factors for the 192 Ir source considered. As a possible application of this calibration methodology for thermoluminescent dosimeters, a practical range of source-detector distances is proposed for quality control of 192 Ir high dose rate sources. (author)

[Actual review of diagnostics and endovascular therapy of intracranial arterial stenoses].

Science.gov (United States)

Gizewski, E R; Weber, R; Forsting, M

2011-02-01

Approximately 6 - 50% of all ischemic strokes are caused by intracranial arterial stenosis (IAS). Despite medical prevention, patients with symptomatic IAS have a high annual risk for recurrent ischemic stroke of about 12%, and up to 19% in the case of high-grade IAS (≥ 70%). Digital subtraction angiography remains the gold standard for the diagnosis and grading of IAS. However, noninvasive imaging techniques including CT angiography, MR angiography, or transcranial Doppler and duplex ultrasound examinations are used in the clinical routine to provide additional information about the brain structure and hemodynamic. However, for technical reasons, the grading of stenoses is sometimes difficult and inaccurate. To date, aspirin is recommended as the treatment of choice in the prevention of recurrent ischemic stroke in patients with IAS. IAS patients who suffer a recurrent ischemic stroke or transient ischemic attack while taking aspirin can be treated with endovascular stenting or angioplasty in specialized centers. The periprocedural complication rate of these endovascular techniques is about 2 - 7% at experienced neuro-interventional centers. The rate of re-stenosis is reported between 10 and 40% depending on patient age and stenosis location. Further randomized studies comparing medical secondary prevention and endovascular therapy are currently being performed. With regard to the improvement of endovascular methods and lower complication rates, the indication for endovascular therapy in IAS could be broadened especially for stenosis in the posterior circulation. © Georg Thieme Verlag KG Stuttgart · New York.

Outdoor γ-ray dose rate in Shariki Village and environmental factors affecting outdoor γ-ray dose rate in IES

International Nuclear Information System (INIS)

Iyogi, Takashi; Hisamatsu, Shun'ichi; Inaba, Jiro

2000-01-01

Previously, we surveyed the outdoor γ-ray dose rate throughout Aomori Prefecture from 1992 to 1995, and found an annual mean dose rate of 51 nGy h -1 . Relatively high dose rates were also observed in several areas (municipalities) of the survey locations. In this study, we examined the detailed distribution of the γ-ray dose rate in one such high dose rate area, Shariki Village. Glass dosemeters were used for the monitoring of cumulative γ-ray dose rate at 10 locations in the village. The dose rate from each radioactive nuclide in the ground at the monitoring locations was measured by using an in situ γ-ray spectrometer with a Ge detector. The results obtained with the glass dosemeters showed that the γ-ray dose rates in Shariki Village varied from 49 to 55 nGy h -1 . Although the dose rates were generally higher than the mean dose in Aomori Prefecture (1992-1995), the rates were lower than other high dose rate areas which had already been measured. The in situ γ-ray spectrometry revealed that these relatively high dose rates were mainly caused by 40 K and Th series radionuclides in the village. The effect of meteorological conditions on the γ-ray dose rate was studied at a monitoring station in the IES site. The dose rate was continuously recorded by a DBM NaI(Tl) scintillation detector system. The mean dose rate obtained when precipitation was sensed was 27 nGy h -1 and higher than when no precipitation was sensed (25 nGy h -1 ). (author)

Outdoor γ-ray dose rate in Mutsu city and environmental factors affecting outdoor γ-ray dose rate in IES

International Nuclear Information System (INIS)

Iyogi, Takashi; Hisamatsu, Shun'ichi; Inaba, Jiro

2001-01-01

Previously, we surveyed outdoor γ-ray dose rates throughout Aomori Prefecture from 1992 to 1995, and found a mean annual dose rate of 28 nGy h -1 . Relatively high dose rates were also observed in several areas (municipalities) of the survey locations. In this study, we examined the detailed distribution of the γ-ray dose rate in one such high dose rate area, Mutsu City. Glass dosemeters were used for the monitoring of cumulative γ-ray dose rate at 10 locations in the city. The dose rate from each radioactive nuclide in the ground at the monitoring locations was measured by using an in situ γ-ray spectrometer with a Ge detector. The results obtained with the glass dosemeters showed that the γ-ray dose rates in Mutsu City varied from 17 to 32 nGy h -1 . Although the dose rates were almost the same as the mean dose in Aomori Prefecture (1992-1995), the rates were lower than other high dose rate areas which had already been measured. The in situ γ-ray spectrometry revealed that these relatively high dose rates were mainly caused by 40 K and Th series radionuclides in the local ground. The effect of meteorological conditions on the γ-ray dose rate was studied at a monitoring station in the IES site. The dose rate was continuously recorded by a DBM NaI(Tl) scintillation detector system. The mean dose rate obtained when precipitation was sensed was 26 nGy h -1 and higher than when no precipitation was sensed (24 nGy h -1 ). (author)

Virtual reality simulation for the optimization of endovascular procedures: current perspectives.

Science.gov (United States)

Rudarakanchana, Nung; Van Herzeele, Isabelle; Desender, Liesbeth; Cheshire, Nicholas J W

2015-01-01

Endovascular technologies are rapidly evolving, often requiring coordination and cooperation between clinicians and technicians from diverse specialties. These multidisciplinary interactions lead to challenges that are reflected in the high rate of errors occurring during endovascular procedures. Endovascular virtual reality (VR) simulation has evolved from simple benchtop devices to full physic simulators with advanced haptics and dynamic imaging and physiological controls. The latest developments in this field include the use of fully immersive simulated hybrid angiosuites to train whole endovascular teams in crisis resource management and novel technologies that enable practitioners to build VR simulations based on patient-specific anatomy. As our understanding of the skills, both technical and nontechnical, required for optimal endovascular performance improves, the requisite tools for objective assessment of these skills are being developed and will further enable the use of VR simulation in the training and assessment of endovascular interventionalists and their entire teams. Simulation training that allows deliberate practice without danger to patients may be key to bridging the gap between new endovascular technology and improved patient outcomes.

High dose rate versus medium dose rate intraluminal brachytherapy in inoperable esophageal carcinoma

International Nuclear Information System (INIS)

Langendijk, J.; Jager, J.; Jong, J. de; Rijken, J.; Pannebakker, M.

1996-01-01

Introduction: The purpose of this study was to compare the results of medium dose rate (MDR) intraluminal brachytherapy (ILBT) and high dose rate (HDR) ILBT in patients with inoperable esophageal carcinoma, with regard to dysphagia, complication rate and survival. Material and methods: Included were 114 patients with inoperable esophageal cancer who were treated with a single session of ILBT. In all cases a single dose of 15 Gy was administered, calculated at a 1 cm radius. Forty-eight patients were treated with MDR ( 137 Cs)ILBT. In June 1990 MDR was replaced by HDR and from then 66 patients were treated with HDR ( 192 Ir). Dysphagia was prospectively scored using a 5-point scale at 6 weeks, 3, 6, 9 and 12 months. Results: No significant differences were noted between the two groups with regard to pretreatment variables. In patients treated with MDR-ILBT improvement of swallowing ability was noted in 30 out of 42 evaluable patients (71%), no change in 9 (21%) and progression of dysphagia in 3 patients (8%), as compared to 34 out of 59 evaluable patients (58%), 16 (27%) and 6 (15%) resp. in de HDR-ILBT group. In the latter category, progression of dysphagia was caused by fistulae in 2 patients. The differences were not significant (ns). Additional treatment in case of recurrent or persistent dysphagia was needed in 50% of the cases in the MDR-ILBT group as compared to 41% in the HDR-ILBT group (ns). The median survival of the MDR-ILBT group was 3.9 months as compared to 4.3 months in the HDR-ILBT group (ns). In 2 patients (4%) treated with MDR-ILBT bronchio-oesphageal fistulae developed at 6 weeks and 2 months. In the HDR-ILBT group fistulae were noted in 7 cases (11%) at 2 weeks, 4 weeks, 2, 3, 3, 4 and 9 months (ns). In all of these cases persistent of recurrent tumour was present. Conclusions: No significant differences were noted with regard to palliation of dysphagia, survival and complication rate between MDR-ILBT and HDR-ILBT in the management of esophageal

Salvage high-dose-rate interstitial brachytherapy for locally recurrent rectal cancer

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Pellizzon, Antonio Cassio Assis, E-mail: acapellizzon@hcancer.org.br [A.C. Camargo Cancer Center, Sao Paulo, SP (Brazil). Departamento de Radioterapia

2016-05-15

For tumors of the lower third of the rectum, the only safe surgical procedure is abdominal-perineal resection. High-dose-rate interstitial brachytherapy is a promising treatment for local recurrence of previously irradiated lower rectal cancer, due to the extremely high concentrated dose delivered to the tumor and the sparing of normal tissue, when compared with a course of external beam radiation therapy. (author)

Results in patients treated with high-dose-rate interstitial brachytherapy for oral tongue cancer

International Nuclear Information System (INIS)

Yamamoto, Michinori; Shirane, Makoto; Ueda, Tsutomu; Miyahara, Nobuyuki

2006-01-01

Eight patients were treated with high-dose-rate interstitial brachytherapy for oral tongue cancer between September 2000 and August 2004. The patient distribution was 1 T1, 5 T2, 1 T3, and 1 T4a. Patients received 50-60 Gy in 10 fractions over seven days with high-dose-rate brachytherapy. Six of the eight patients were treated with a combination of external beam radiotherapy (20-30 Gy) and interstitial brachytherapy. The two-year primary local control rate was 83% for initial case. High-dose-rate brachytherapy was performed safely even for an aged person, and was a useful treatment modality for oral tongue cancer. (author)

Surface applicators for high dose rate brachytherapy in AIDS-related kaposi's sarcoma

International Nuclear Information System (INIS)

Evans, Michael D.C.; Yassa, Mariam; Podgorsak, Ervin B.; Roman, Ted N.; Schreiner, L. John; Souhami, Luis

1997-01-01

Purpose: The development of commercially available surface applicators using high dose rate remote afterloading devices has enabled radiotherapy centers to treat selected superficial lesions using a remote afterloading brachytherapy unit. The dosimetric parameters of these applicators, the clinical implementation of this technique, and a review of the initial patient treatment regimes are presented. Methods and Materials: A set of six fixed-diameter (1, 2, and 3 cm), tungsten/steel surface applicators is available for use with a single stepping-source (Ir-192, 370 GBq) high dose rate afterloader. The source can be positioned either in a parallel or perpendicular orientation to the treatment plane at the center of a conical aperture that sits at an SSD of approximately 15 mm and is used with a 1-mm thick removable plastic cap. The surface dose rates, percent depth dose, and off-axis ratios were measured. A custom-built, ceiling-mounted immobilization device secures the applicator on the surface of the patient's lesion during treatment. Results: Between November 1994, and September 1996, 16 AIDS-related Kaposi's sarcoma patients having a total of 120 lesions have been treated with palliative intent. Treatment sites were distributed between the head and neck, extremity, and torso. Doses ranged from 8 to 20 Gy, with a median dose of 10 Gy delivered in a single fraction. Treatments were well tolerated with minimal skin reaction, except for patients with lesions treated to 20 Gy who developed moderate/severe desquamation. Conclusion: Radiotherapy centers equipped with a high dose rate remote afterloading unit may treat small selected surface lesions with commercially available surface applicators. These surface applicators must be used with a protective cap to eliminate electron contamination. The optimal surface dose appears to be either 10 or 15 Gy depending upon the height of the lesion

High-dose-rate brachytherapy alone post-hysterectomy for endometrial cancer

International Nuclear Information System (INIS)

MacLeod, Craig; Fowler, Allan; Duval, Peter; D'Costa, Ieta; Dalrymple, Chris; Firth, Ian; Elliott, Peter; Atkinson, Ken; Carter, Jonathan

1998-01-01

Purpose: To evaluate the outcome of post-hysterectomy adjuvant vaginal high-dose-rate (HDR) brachytherapy. Methods and Materials: A retrospective analysis was performed on a series of 143 patients with endometrial cancer treated with HDR brachytherapy alone post-hysterectomy from 1985 to June 1993. Of these patients, 141 received 34 Gy in four fractions prescribed to the vaginal mucosa in a 2-week period. The median follow-up was 6.9 years. Patients were analyzed for treatment parameters, survival, local recurrence, distant relapse, and toxicity. Results: Five-year relapse free survival and overall survival was 100% and 88% for Stage 1A, 98% and 94% for Stage IB, 100% and 86% for Stage IC, and 92% and 92% for Stage IIA. The overall vaginal recurrence rate was 1.4%. The overall late-toxicity rate was low, and no RTOG grade 3, 4, or 5 complications were recorded. Conclusion: These results are similar to reported international series that have used either low-dose-rate or HDR brachytherapy. The biological effective dose was low for both acute and late responding tissues compared with some of the HDR brachytherapy series, and supports using this lower dose and possibly decreasing late side-effects with no apparent increased risk of vaginal recurrence

Dependence of total dose response of bipolar linear microcircuits on applied dose rate

International Nuclear Information System (INIS)

McClure, S.; Will, W.; Perry, G.; Pease, R.L.

1994-01-01

The effect of dose rate on the total dose radiation hardness of three commercial bipolar linear microcircuits is investigated. Total dose tests of linear bipolar microcircuits show larger degradation at 0.167 rad/s than at 90 rad/s even after the high dose rate test is followed by a room temperature plus a 100 C anneal. No systematic correlation could be found for degradation at low dose rate versus high dose rate and anneal. Comparison of the low dose rate with the high dose rate anneal data indicates that MIL-STD-883, method 1019.4 is not a worst-case test method when applied to bipolar microcircuits for low dose rate space applications

Genotoxic effects of high dose rate X-ray and low dose rate gamma radiation in ApcMin/+ mice.

Science.gov (United States)

Graupner, Anne; Eide, Dag M; Brede, Dag A; Ellender, Michele; Lindbo Hansen, Elisabeth; Oughton, Deborah H; Bouffler, Simon D; Brunborg, Gunnar; Olsen, Ann Karin

2017-10-01

Risk estimates for radiation-induced cancer in humans are based on epidemiological data largely drawn from the Japanese atomic bomb survivor studies, which received an acute high dose rate (HDR) ionising radiation. Limited knowledge exists about the effects of chronic low dose rate (LDR) exposure, particularly with respect to the application of the dose and dose rate effectiveness factor. As part of a study to investigate the development of colon cancer following chronic LDR vs. acute HDR radiation, this study presents the results of genotoxic effects in blood of exposed mice. CBAB6 F1 Apc +/+ (wild type) and Apc Min/+ mice were chronically exposed to estimated whole body absorbed doses of 1.7 or 3.2 Gy 60 Co-γ-rays at a LDR (2.2 mGy h -1 ) or acutely exposed to 2.6 Gy HDR X-rays (1.3 Gy min -1 ). Genotoxic endpoints assessed in blood included chromosomal damage (flow cytometry based micronuclei (MN) assay), mutation analyses (Pig-a gene mutation assay), and levels of DNA lesions (Comet assay, single-strand breaks (ssb), alkali labile sites (als), oxidized DNA bases). Ionising radiation (ca. 3 Gy) induced genotoxic effects dependent on the dose rate. Chromosomal aberrations (MN assay) increased 3- and 10-fold after chronic LDR and acute HDR, respectively. Phenotypic mutation frequencies as well as DNA lesions (ssb/als) were modulated after acute HDR but not after chronic LDR. The Apc Min/+ genotype did not influence the outcome in any of the investigated endpoints. The results herein will add to the scant data available on genotoxic effects following chronic LDR of ionising radiation. Environ. Mol. Mutagen. 58:560-569, 2017. © 2017 The Authors Environmental and Molecular Mutagenesis published by Wiley Periodicals, Inc. on behalf of Environmental Mutagen Society. © 2017 The Authors Environmental and Molecular Mutagenesis published by Wiley Periodicals, Inc. on behalf of Environmental Mutagen Society.

Comparison of traditional low-dose-rate to optimized and nonoptimized high-dose-rate tandem and ovoid dosimetry

International Nuclear Information System (INIS)

Decker, William E.; Erickson, Beth; Albano, Katherine; Gillin, Michael

2001-01-01

Purpose: Few dose specification guidelines exist when attempting to perform high-dose-rate (HDR) dosimetry. The purpose of this study was to model low-dose-rate (LDR) dosimetry, using parameters common in HDR dosimetry, to achieve the 'pear-shape' dose distribution achieved with LDR tandem and ovoid applications. Methods and Materials: Radiographs of Fletcher-Suit LDR applicators and Nucletron 'Fletcher-like' HDR applicators were taken with the applicators in an idealized geometry. Traditional Fletcher loadings of 3M Cs-137 sources and the Theratronics Planning System were used for LDR dosimetry. HDR dosimetry was performed using the Nucletron Microselectron HDR UPS V11.22 with an Ir-192 source. Dose optimization points were initially located along a line 2 cm lateral to the tandem, beginning at the tandem tip at 0.5-cm intervals, ending at the sail, and optimized to 100% of the point A dose. A single dose optimization point was also placed laterally from the center of each ovoid equal to the radius of the ovoid (ovoid surface dose). For purposes of comparison, dose was also calculated for points A and B, and a point located 1 cm superior to the tandem tip in the plane of the tandem, (point F). Four- and 6-cm tandem lengths and 2.0-, 2.5-, and 3.0-cm ovoid diameters were used for this study. Based on initial findings, dose optimization schemes were developed to best approximate LDR dosimetry. Finally, radiographs were obtained of HDR applications in two patients. These radiographs were used to compare the optimization schemes with 'nonoptimized' treatment plans. Results: Calculated doses for points A and B were similar for LDR, optimized HDR, and nonoptimized HDR. The optimization scheme that used tapered dose points at the tandem tip and optimized a single ovoid surface point on each ovoid to 170% of point A resulted in a good approximation of LDR dosimetry. Nonoptimized HDR resulted in higher doses at point F, the bladder, and at points lateral to the tandem tip

Low mortality rates after endovascular aortic repair expand use to high-risk patients.

Science.gov (United States)

Adkar, Shaunak S; Turner, Megan C; Leraas, Harold J; Gilmore, Brian F; Nag, Uttara; Turley, Ryan S; Shortell, Cynthia K; Mureebe, Leila

2018-02-01

The 2010 endovascular aneurysm repair (EVAR) trial 2 (EVAR 2) reported that patients with comorbidity profiles rendering them unfit for open aneurysm repair who underwent EVAR did not experience a survival advantage compared with those who did not undergo intervention. These patients experienced a 30-day mortality of 7.3%, whereas reports from similar cohorts reported far lower mortality rates. The primary objective of our study was to compare the incidence of 30-day mortality in low- and high-risk patients undergoing EVAR in a contemporary data set, using patient risk stratification criteria from EVAR 2. Secondarily, we sought to identify risk factors associated with a disproportionate contribution to 30-day mortality risk. Data were obtained from the 2005 to 2013 American College of Surgeons National Surgical Quality Improvement Program (ACS NSQIP) Participant Use Data Files (N = 24,813). Patients were included in the high-risk cohort with the presence of renal, respiratory, or cardiac preoperative criteria alone or in combination. Renal impairment criteria were defined as dialysis and creatinine concentration >2.26 mg/dL. Respiratory impairment criteria included history of chronic obstructive pulmonary disease and preoperative ventilator support. Cardiac impairment criteria included history of myocardial infarction, congestive heart failure, angina, and prior coronary intervention. Patient and procedural characteristics and 30-day postoperative outcomes were compared using Pearson χ 2 tests for categorical variables and Wilcoxon rank sum tests for continuous variables. Among 24,813 patients undergoing EVAR, 12,043 (48%) patients were characterized as high risk (at least one impairment criterion); 12,770 (52%) patients were stratified as low risk. The 30-day mortality rate was 1.9% in the high-risk cohort compared with the 7.3% reported by EVAR 2, and it was higher in the high-risk cohort compared with the low-risk cohort (1.9% vs 0.9%; P < .001). Whereas the

Dose Rate Effects in Linear Bipolar Transistors

Science.gov (United States)

Johnston, Allan; Swimm, Randall; Harris, R. D.; Thorbourn, Dennis

2011-01-01

Dose rate effects are examined in linear bipolar transistors at high and low dose rates. At high dose rates, approximately 50% of the damage anneals at room temperature, even though these devices exhibit enhanced damage at low dose rate. The unexpected recovery of a significant fraction of the damage after tests at high dose rate requires changes in existing test standards. Tests at low temperature with a one-second radiation pulse width show that damage continues to increase for more than 3000 seconds afterward, consistent with predictions of the CTRW model for oxides with a thickness of 700 nm.

Virtual reality simulation for the optimization of endovascular procedures: current perspectives

Directory of Open Access Journals (Sweden)

Rudarakanchana N

2015-03-01

Full Text Available Nung Rudarakanchana,1 Isabelle Van Herzeele,2 Liesbeth Desender,2 Nicholas JW Cheshire1 1Department of Surgery, Imperial College London, London, UK; 2Department of Thoracic and Vascular Surgery, Ghent University Hospital, Ghent, BelgiumOn behalf of EVEREST (European Virtual reality Endovascular RESearch TeamAbstract: Endovascular technologies are rapidly evolving, often requiring coordination and cooperation between clinicians and technicians from diverse specialties. These multidisciplinary interactions lead to challenges that are reflected in the high rate of errors occurring during endovascular procedures. Endovascular virtual reality (VR simulation has evolved from simple benchtop devices to full physic simulators with advanced haptics and dynamic imaging and physiological controls. The latest developments in this field include the use of fully immersive simulated hybrid angiosuites to train whole endovascular teams in crisis resource management and novel technologies that enable practitioners to build VR simulations based on patient-specific anatomy. As our understanding of the skills, both technical and nontechnical, required for optimal endovascular performance improves, the requisite tools for objective assessment of these skills are being developed and will further enable the use of VR simulation in the training and assessment of endovascular interventionalists and their entire teams. Simulation training that allows deliberate practice without danger to patients may be key to bridging the gap between new endovascular technology and improved patient outcomes.Keywords: virtual reality, simulation, endovascular, aneurysm

Treatment of the prostate cancer with high dose rate brachytherapy

International Nuclear Information System (INIS)

Martinez, Alvaro; Torres Silva, Felipe

2002-01-01

The prostate cancer treatment in early stages is controversial. The high dose rate brachytherapy has been used like monotherapy or boost with external beam radiotherapy in advanced disease. This paper describes the technique and the advantages over other modalities

Biological effective doses in the intracavitary high dose rate brachytherapy of cervical cancer

Directory of Open Access Journals (Sweden)

Y. Sobita Devi

2011-12-01

Full Text Available Purpose: The aim of this study is to evaluate the decrease of biological equivalent dose and its correlation withlocal/loco-regional control of tumour in the treatment of cervical cancer when the strength of the Ir-192 high dose rate(HDR brachytherapy (BT source is reduced to single, double and triple half life in relation to original strength of10 Ci (~ 4.081 cGy x m2 x h–1. Material and methods: A retrospective study was carried out on 52 cervical cancer patients with stage II and IIItreated with fractionated HDR-BT following external beam radiation therapy (EBRT. International Commission onRadiation Units and Measurement (ICRU points were defined according to ICRU Report 38, using two orthogonal radiographimages taken by Simulator (Simulix HQ. Biologically effective dose (BED was calculated at point A for diffe -rent Ir-192 source strength and its possible correlation with local/loco-regional tumour control was discussed. Result: The increase of treatment time per fraction of dose due to the fall of dose rate especially in HDR-BT of cervicalcancer results in reduction in BED of 2.59%, 7.02% and 13.68% with single, double and triple half life reduction ofsource strength, respectively. The probabilities of disease recurrence (local/loco-regional within 26 months are expectedas 0.12, 0.12, 0.16, 0.39 and 0.80 for source strength of 4.081, 2.041, 1.020, 0.510 and 0.347 cGy x m2 x h–1, respectively.The percentages of dose increase required to maintain the same BED with respect to initial BED were estimated as1.71, 5.00, 11.00 and 15.86 for the dose rate of 24.7, 12.4, 6.2 and 4.2 Gy/hr at point A, respectively. Conclusions: This retrospective study of cervical cancer patients treated with HDR-BT at different Ir-192 sourcestrength shows reduction in disease free survival according to the increase in treatment time duration per fraction.The probable result could be associated with the decrease of biological equivalent dose to point A. Clinical

Interstitial high-dose rate brachytherapy as boost for anal canal cancer

International Nuclear Information System (INIS)

Falk, Alexander Tuan; Claren, Audrey; Benezery, Karen; François, Eric; Gautier, Mathieu; Gerard, Jean-Pierre; Hannoun-Levi, Jean-Michel

2014-01-01

To assess clinical outcomes of patients treated with a high-dose rate brachytherapy boost for anal canal cancer (ACC). From August 2005 to February 2013, 28 patients presenting an ACC treated by split-course external beam radiotherapy (EBRT) and HDR brachytherapy with or without chemotherapy in a French regional cancer center in Nice were retrospectively analyzed. Median age was 60.6 years [34 – 83], 25 patients presented a squamous cell carcinoma and 3 an adenocarcinoma; 21 received chemotherapy. Median dose of EBRT was 45 Gy [43.2 – 52]. Median dose of HDR brachytherapy was 12 Gy [10 - 15] with a median duration of 2 days. Median overall treatment time was 63 days and median delay between EBRT and brachytherapy was 20 days. Two-year local relapse free, metastatic free, disease free and overall survivals were 83%, 81.9%, 71.8% and 87.7% respectively. Acute toxicities were frequent but not severe with mostly grade 1 toxicities: 37% of genito-urinary, 40.7% of gastro-intestinal and 3.7% of cutaneous toxicities. Late toxicities were mainly G1 (43.1%) and G2 (22%). Two-year colostomy-free survival was 75.1%, one patient had a definitive sphincter amputation. High-dose rate brachytherapy for anal canal carcinoma as boost represents a feasible technique compared to low or pulsed-dose rate brachytherapy. This technique remains an excellent approach to precisely boost the tumor in reducing the overall treatment time

Biological influence from low dose and low-dose rate radiation

International Nuclear Information System (INIS)

Magae, Junji

2007-01-01

Although living organisms have defense mechanisms for radioadaptive response, the influence is considered to vary qualitatively and quantitatively for low dose and high dose, as well as for low-dose rate and high-dose rate. This article describes the bioresponse to low dose and low-dose rate. Among various biomolecules, DNA is the most sensitive to radiation, and accurate replication of DNA is an essential requirement for the survival of living organisms. Also, the influence of active enzymes resulted from the effect of radiation on enzymes in the body is larger than the direct influence of radiation on the body. After this, the article describes the carcinogenic risk by low-dose radiation, and then so-called Hormesis effect to create cancer inhibition effect by stimulating active physiology. (S.K.)

Effects of high dose rate gamma radiation on survival and reproduction of Biomphalaria glabrata

Energy Technology Data Exchange (ETDEWEB)

Cantinha, Rebeca S.; Nakano, Eliana [Instituto Butantan, Sao Paulo, SP (Brazil). Lab. de Parasitologia], e-mail: rebecanuclear@gmail.com, e-mail: eliananakano@butantan.gov.br; Borrely, Sueli I. [Instituto de Pesquisas Energeticas e Nucleares (IPEN-CNEN/SP), Sao Paulo, SP (Brazil). Centro de Tecnologia das Radiacoes], e-mail: sborrely@ipen.br; Amaral, Ademir; Melo, Ana M.M.A. [Universidade Federal de Pernambuco (UFPE), Recife, PE (Brazil). Dept. de Energia Nuclear. Grupo de Estudos em Radioprotecao e Radioecologia (GERAR)], e-mail: amaral@ufpe.br; Silva, Luanna R.S. [Universidade Federal de Pernambuco (UFPE), Recife, PE (Brazil). Dept. de Biofisica e Radiobiologia. Lab. de Radiobiologia], e-mail: amdemelo@hotmail.com, e-mail: luannaribeiro_lua@hotmail.com

2009-07-01

Ionizing radiations are known as mutagenic agents, causing lethality and infertility. This characteristic has motivated its application on animal biological control. In this context, the freshwater snail Biomphalaria glabrata can be considered an excellent experimental model to study effects of ionizing radiations on lethality and reproduction. This work was designed to evaluate effects of {sup 60}Co gamma radiation at high dose rate (10.04 kGy/h) on B. glabrata. For this purpose, adult snails were selected and exposed to doses ranging from 20 to 100 Gy, with 10 Gy intervals; one group was kept as control. There was not effect of dose rate in the lethality of gamma radiation; the value of 64,3 Gy of LD{sub 50} obtained in our study was similar to that obtained by other authors with low dose rates. Nevertheless, our data suggest that there was a dose rate effect in the reproduction. On all dose levels, radiation improved the production of embryos for all exposed individuals. However, viability indexes were below 6% and, even 65 days after irradiation, fertility was not recovered. These results are not in agreement with other studies using low dose rates. Lethality was obtained in all groups irradiated, and the highest doses presented percentiles of dead animals above 50%. The results demonstrated that doses of 20 and 30 Gy were ideal for population control of B. glabrata. Further studies are needed; nevertheless, this research evidenced great potential of high dose rate gamma radiation on B. glabrata reproductive control. (author)

Effects of high dose rate gamma radiation on survival and reproduction of Biomphalaria glabrata

International Nuclear Information System (INIS)

Cantinha, Rebeca S.; Nakano, Eliana; Silva, Luanna R.S.

2009-01-01

Ionizing radiations are known as mutagenic agents, causing lethality and infertility. This characteristic has motivated its application on animal biological control. In this context, the freshwater snail Biomphalaria glabrata can be considered an excellent experimental model to study effects of ionizing radiations on lethality and reproduction. This work was designed to evaluate effects of 60 Co gamma radiation at high dose rate (10.04 kGy/h) on B. glabrata. For this purpose, adult snails were selected and exposed to doses ranging from 20 to 100 Gy, with 10 Gy intervals; one group was kept as control. There was not effect of dose rate in the lethality of gamma radiation; the value of 64,3 Gy of LD 50 obtained in our study was similar to that obtained by other authors with low dose rates. Nevertheless, our data suggest that there was a dose rate effect in the reproduction. On all dose levels, radiation improved the production of embryos for all exposed individuals. However, viability indexes were below 6% and, even 65 days after irradiation, fertility was not recovered. These results are not in agreement with other studies using low dose rates. Lethality was obtained in all groups irradiated, and the highest doses presented percentiles of dead animals above 50%. The results demonstrated that doses of 20 and 30 Gy were ideal for population control of B. glabrata. Further studies are needed; nevertheless, this research evidenced great potential of high dose rate gamma radiation on B. glabrata reproductive control. (author)

[Endovascular surgery in the war].

Science.gov (United States)

Reva, V A; Samokhvalov, I M

2015-01-01

Rapid growth of medical technologies has led to implementation of endovascular methods of diagnosis and treatment into rapidly developing battlefield surgery. This work based on analysing all available current publications generalizes the data on using endovascular surgery in combat vascular injury. During the Korean war (1950-1953) American surgeons for the first time performed endovascular balloon occlusion of the aorta - the first intravascular intervention carried out in a zone of combat operations. Half a century thereafter, with the beginning of the war in Afghanistan (2001) and in Iraq (2003) surgeons of central hospitals of the USA Armed Forces began performing delayed endovascular operations to the wounded. The development of technologies, advent of mobile angiographs made it possible to later on implement high-tech endovascular interventions in a zone of combat operations. At first, more often they performed implantation of cava filters, somewhat afterward - angioembolization of damaged accessory vessels, stenting and endovascular repair of major arteries. The first in the theatre of war endovascular prosthetic repair of the thoracic aorta for severe closed injury was performed in 2008. Russian experience of using endovascular surgery in combat injuries is limited to diagnostic angiography and regional intraarterial perfusion. Despite the advent of stationary angiographs in large hospitals of the RF Ministry of Defence in the early 1990s, endovascular operations for combat vascular injury are casuistic. Foreign experience in active implementation of endovascular technologies to treatment of war-time injuries has substantiated feasibility of using intravascular interventions in tertiary care military hospitals. Carrying out basic training courses on endovascular surgery should become an organic part of preparing multimodality general battlefield surgeons rendering care on the theatre of combat operations.

High-voltage power supply of ND6 portable dose rate meter

International Nuclear Information System (INIS)

Wang Shaling

2001-01-01

Portable dose rate meter needs to be equipped with a set of high-voltage power supply which is supplied by batteries and has characteristic of high quality, low energy expense and small size. The author introduces application conditions and performance guide line

Endovascular Management of Acute Bleeding Arterioenteric Fistulas

International Nuclear Information System (INIS)

Leonhardt, Henrik; Mellander, Stefan; Snygg, Johan; Loenn, Lars

2008-01-01

The objective of this study was to review the outcome of endovascular transcatheter repair of emergent arterioenteric fistulas. Cases of abdominal arterioenteric fistulas (defined as a fistula between a major artery and the small intestine or colon, thus not the esophagus or stomach), diagnosed over the 3-year period between December 2002 and December 2005 at our institution, were retrospectively reviewed. Five patients with severe enteric bleeding underwent angiography and endovascular repair. Four presented primary arterioenteric fistulas, and one presented a secondary aortoenteric fistula. All had massive persistent bleeding with hypotension despite volume substitution and transfusion by the time of endovascular management. Outcome after treatment of these patients was investigated for major procedure-related complications, recurrence, reintervention, morbidity, and mortality. Mean follow-up time was 3 months (range, 1-6 months). All massive bleeding was controlled by occlusive balloon catheters. Four fistulas were successfully sealed with stent-grafts, resulting in a technical success rate of 80%. One patient was circulatory stabilized by endovascular management but needed immediate further open surgery. There were no procedure-related major complications. Mean hospital stay after the initial endovascular intervention was 19 days. Rebleeding occurred in four patients (80%) after a free interval of 2 weeks or longer. During the follow-up period three patients needed reintervention. The in-hospital mortality was 20% and the 30-day mortality was 40%. The midterm outcome was poor, due to comorbidities or rebleeding, with a mortality of 80% within 6 months. In conclusion, endovascular repair is an efficient and safe method to stabilize patients with life-threatening bleeding arterioenteric fistulas in the emergent episode. However, in this group of patients with severe comorbidities, the risk of rebleeding is high and further intervention must be considered

Audits in high dose rate brachytherapy in Brazil

International Nuclear Information System (INIS)

Marechal, M.H.; Rosa, L.A.; Velasco, A.; Paiva, E. de; Goncalves, M.; Castelo, L.C.

2002-01-01

The lack of well established dosimetry protocols for HDR sources is a point of great concern regarding the uniformity of procedures within a particular country. The main objective of this paper is to report the results of an implementation of the audit program in dosimetry of high dose rate brachytherapy sources used by the radiation therapy centers in Brazil. In Brazil, among 169 radiotherapy centers, 35 have HDR brachytherapy systems. This program started in August 2001 and until now eight radiotherapy services were audited. The audit program consists of the visit in loco to each center and the evaluation of the intensity of the source with a well type chamber specially design for HDR 192 Ir sources. The measurements was carried out with a HDR1000PLUS Brachytherapy Well Type Chamber and a MAX 4000 Electrometer, both manufactured by Standard Imaging Inc. The chamber was calibrated in air kerma strength by the Accredited Dosimetry Calibration Laboratory, Department of Medical Physics, University of Wisconsin in the USA. The same chamber was calibrated in Brazil using a 192 lr high dose rate source whose intensity was determined by 60 Co gamma rays and 250 kV x rays interpolation methodology. The Nk of 60 Co and 250 kV x rays were provided by the Brazilian National Standard Laboratory for Ionizing Radiation (LMNRI)

Post-operative high dose rate brachytherapy in patients with low to intermediate risk endometrial cancer

International Nuclear Information System (INIS)

Pearcey, R.G.; Petereit, D.G.

2000-01-01

This paper investigates the outcome using different dose/fractionation schedules in high dose rate (HDR) post-operative vaginal vault radiotherapy in patients with low to intermediate risk endometrial cancer. The world literature was reviewed and thirteen series were analyzed representing 1800 cases. A total of 12 vaginal vault recurrences were identified representing an overall vaginal control rate of 99.3%. A wide range of dose fractionation schedules and techniques have been reported. In order to analyze a dose response relationship for tumor control and complications, the biologically effective doses to the tumor and late responding tissues were calculated using the linear quadratic model. A threshold was identified for complications, but not vaginal control. While dose fractionation schedules that delivered a biologically effective dose to the late responding tissues in excess of 100 Gy 3 (LQED = 60 Gy) predicted for late complications, dose fractionation schedules that delivered a modest dose to the vaginal surface (50 Gy 10 or LQED = 30 Gy) appeared tumoricidal with vaginal control rates of at least 98%. By using convenient, modest dose fractionation schedules, HDR vaginal vault - brachytherapy yields very high local control and extremely low morbidity rates. (author)

Independent technique of verifying high-dose rate (HDR) brachytherapy treatment plans

International Nuclear Information System (INIS)

Saw, Cheng B.; Korb, Leroy J.; Darnell, Brenda; Krishna, K. V.; Ulewicz, Dennis

1998-01-01

Purpose: An independent technique for verifying high-dose rate (HDR) brachytherapy treatment plans has been formulated and validated clinically. Methods and Materials: In HDR brachytherapy, dwell times at respective dwell positions are computed, using an optimization algorithm in a HDR treatment-planning system to deliver a specified dose to many target points simultaneously. Because of the variability of dwell times, concerns have been expressed regarding the ability of the algorithm to compute the correct dose. To address this concern, a commercially available low-dose rate (LDR) algorithm was used to compute the doses at defined distances, based on the dwell times obtained from the HDR treatment plans. The percent deviation between doses computed using the HDR and LDR algorithms were reviewed for HDR procedures performed over the last year. Results: In this retrospective study, the difference between computed doses using the HDR and LDR algorithms was found to be within 5% for about 80% of the HDR procedures. All of the reviewed procedures have dose differences of less than 10%. Conclusion: An independent technique for verifying HDR brachytherapy treatment plans has been validated based on clinical data. Provided both systems are available, this technique is universal in its applications and not limited to either a particular implant applicator, implant site, or implant type

Total skin high-dose-rate electron therapy dosimetry using TG-51

International Nuclear Information System (INIS)

Gossman, Michael S.; Sharma, Subhash C.

2004-01-01

An approach to dosimetry for total skin electron therapy (TSET) is discussed using the currently accepted TG-51 high-energy calibration protocol. The methodology incorporates water phantom data for absolute calibration and plastic phantom data for efficient reference dosimetry. The scheme is simplified to include the high-dose-rate mode conversion and provides support for its use, as it becomes more available on newer linear accelerators. Using a 6-field, modified Stanford technique, one may follow the process for accurate determination of absorbed dose

Australian high-dose-rate brachytherapy protocols for gynaecological malignancy

International Nuclear Information System (INIS)

MacLeod, C.; Dally, M.; Stevens, M.; Thornton, D.; Carruthers, S.; Jeal, P.

2001-01-01

There is no consensus over the optimal dose fractionation schedules for high-dose-rate (HDR) brachytherapy used for gynaecological malignancy. In Australian public hospital departments of radiation oncology, HDR brachytherapy for gynaecological cancer is being more commonly used. A survey of public departments that are using this technology, or that plan to introduce this technology, was performed. Their current protocols are presented. In general, protocols are similar biologically; however, the practical aspects such as the number of fractions given do vary and may reflect resource restrictions or, alternatively, differences in interpretations of the literature and of the best protocols by clinicians. Copyright (2001) Blackwell Science Pty Ltd

Controversies in external beam and high dose rate brachytherapy of oesophageal cancer

International Nuclear Information System (INIS)

Sur, R.K.; Levin, V.C.; Malas, Simon; Donde, Bernard

1994-01-01

Various controversies in the treatment of oesophageal carcinoma with external beam radiotherapy and high dose rate intracavitary irradiation have been reviewed. Conflicting results from different parts of the world has made it difficult to optimize the radiation dose that may give the best results. More studies and longer follow-up are needed before a definite conclusion can be made on the optimization of dose. (author). 18 refs., 2 tabs

In phantom calibration of a high dose rate remote afterloading device

International Nuclear Information System (INIS)

Alfonso, R.; Tolede, P.; Pich, V.

1995-01-01

The high dose-rate (HDR) brachytherapy in Cuba is based on soviet made devices type AGAT-V. In order to calibration one of these for clinical use a method based of the different measurement of absorbed dose at the reference point B in a paraffin phantom was developed. The results of the calibration are shown. From these results an analysis was made of the effective doses to prescription point a considering the Lineal-Quadratic model. The clinical results by using the AGAT-V device are displayed in a comparative way

Development of Real-Time Measurement of Effective Dose for High Dose Rate Neutron Fields

International Nuclear Information System (INIS)

Braby, L. A.; Reece, W. D.; Hsu, W. H.

2003-01-01

Studies of the effects of low doses of ionizing radiation require sources of radiation which are well characterized in terms of the dose and the quality of the radiation. One of the best measures of the quality of neutron irradiation is the dose mean lineal energy. At very low dose rates this can be determined by measuring individual energy deposition events, and calculating the dose mean of the event size. However, at the dose rates that are normally required for biology experiments, the individual events can not be separated by radiation detectors. However, the total energy deposited in a specified time interval can be measured. This total energy has a random variation which depends on the size of the individual events, so the dose mean lineal energy can be calculated from the variance of repeated measurements of the energy deposited in a fixed time. We have developed a specialized charge integration circuit for the measurement of the charge produced in a small ion chamber in typical neutron irradiation experiments. We have also developed 4.3 mm diameter ion chambers with both tissue equivalent and carbon walls for the purpose of measuring dose mean lineal energy due to all radiations and due to all radiations except neutrons, respectively. By adjusting the gas pressure in the ion chamber, it can be made to simulate tissue volumes from a few nanometers to a few millimeters in diameter. The charge is integrated for 0.1 seconds, and the resulting pulse height is recorded by a multi channel analyzer. The system has been used in a variety of photon and neutron radiation fields, and measured values of dose and dose mean lineal energy are consistent with values extrapolated from measurements made by other techniques at much lower dose rates. It is expected that this technique will prove to be much more reliable than extrapolations from measurements made at low dose rates because these low dose rate exposures generally do not accurately reproduce the attenuation and

Salvage high-dose-rate brachytherapy for local prostate cancer recurrence after radical radiotherapy

Directory of Open Access Journals (Sweden)

V. A. Solodkiy

2016-01-01

Full Text Available Studies salvage interstitial radiation therapy for recurrent prostate cancer, launched at the end of the XX century. In recent years, more and more attention is paid to high-dose-rate brachytherapy (HDR-BT as a method of treating local recurrence.The purpose of research – preliminary clinical results of salvage high-dose-rate brachytherapy applied in cases of suspected local recurrence or of residual tumour after radiotherapy.Preliminary findings indicate the possibility of using HDR-BT, achieving local tumor control with low genitourinary toxicity.

The status of low dose rate and future of high dose rate Cf-252 brachytherapy

International Nuclear Information System (INIS)

Rivard, M.J.; Wierzbicki, J.G.; Van den Heuvel, F.; Chuba, P.J.; Fontanesi, J.

1997-12-01

This work describes the current status of the US low dose rate (LDR) Cf-252 brachytherapy program. The efforts undertaken towards development of a high dose rate (HDR) remotely after loaded Cf-252 source, which can accommodate 1 mg or greater Cf-252, are also described. This HDR effort is a collaboration between Oak Ridge National Laboratory (ORNL), commercial remote after loader manufactures, the Gershenson Radiation Oncology Center (ROC), and Wayne State University. To achieve this goal, several advances in isotope chemistry and source preparation at ORNL must be achieved to yield a specific material source loading of greater than or equal 1 mg Cf-252 per mm3. Development work with both radioactive and non-radioactive stand-ins for Cf-252 have indicated the feasibility of fabricating such sources. As a result, the decreased catheter diameter and computer controlled source placement will permit additional sites (e.g. brain, breast, prostate, lung, parotid, etc.) to be treated effectively with Cf-252 sources. Additional work at the Radiochemical Engineering and Development Center (REDC) remains in source fabrication, after loader modification, and safe design. The current LDR Cf-252 Treatment Suite at the ROC is shielded and licensed to hold up to 1 mg of Cf-252. This was designed to maintain cumulative personnel exposure, both external to the room and in direct isotope handling, at less than 20 microSv/hr. However, cumulative exposure may be greatly decreased if a Cf-252 HDR unit is employed which would eliminate direct isotope handling and decrease treatment times from tilde 3 hours to an expected range of 3 to 15 minutes. Such a Cf-252 HDR source will also demonstrate improved dose distributions over current LDR treatments due to the ability to step the point-like source throughout the target volume and weight the dwell time accordingly

Low and high dose rate heavy ion radiation-induced intestinal and colonic tumorigenesis in APC1638N/+ mice

Science.gov (United States)

Suman, Shubhankar; Kumar, Santosh; Moon, Bo-Hyun; Fornace, Albert J.; Datta, Kamal

2017-05-01

Ionizing radiation (IR) is a recognized risk factor for colorectal cancer (CRC) and astronauts undertaking long duration space missions are expected to receive IR doses in excess of permissible limits with implications for colorectal carcinogenesis. Exposure to IR in outer space occurs at low doses and dose rates, and energetic heavy ions due to their high linear energy transfer (high-LET) characteristics remain a major concern for CRC risk in astronauts. Previously, we have demonstrated that intestinal tumorigenesis in a mouse model (APC1638N/+) of human colorectal cancer was significantly higher after exposure to high dose rate energetic heavy ions relative to low-LET γ radiation. The purpose of the current study was to compare intestinal tumorigenesis in APC1638N/+ mice after exposure to energetic heavy ions at high (50 cGy/min) and relatively low (0.33 cGy/min) dose rate. Male and female mice (6-8 weeks old) were exposed to either 10 or 50 cGy of 28Si (energy: 300 MeV/n; LET: 70 keV/μm) or 56Fe (energy: 1000 MeV/n; LET: 148 keV/μm) ions at NASA Space Radiation Laboratory in Brookhaven National Laboratory. Mice (n = 20 mice/group) were euthanized and intestinal and colon tumor frequency and size were counted 150 days after radiation exposure. Intestinal tumorigenesis in male mice exposed to 56Fe was similar for high and low dose rate exposures. Although male mice showed a decreasing trend at low dose rate relative to high dose rate exposures, the differences in tumor frequency between the two types of exposures were not statistically significant after 28Si radiation. In female mice, intestinal tumor frequency was similar for both radiation type and dose rates tested. In both male and female mice intestinal tumor size was not different after high and low dose rate radiation exposures. Colon tumor frequency in male and female mice after high and low dose rate energetic heavy ions was also not significantly different. In conclusion, intestinal and colonic tumor

Development of miniature γ dose rate monitor with high sensitivity

International Nuclear Information System (INIS)

Shi Huilu; Tuo Xianguo; Xi Dashun; Tang Rong; Mu Keliang; Yang Jianbo

2009-01-01

This paper introduces a miniature γ dose rate monitor with high sensitivity which design based on single chip microcomputer, it can continue monitoring γ dose rate and then choose wire or wireless communications to sent the monitoring data to host according to the actual conditions. It has two kinds of power supply system, AC power supply system and battery which can be chose by concrete circumstances. The design idea and implementation technology of hardware and software and the system structure of the monitor are detailed illustrated in this paper. The experimental results show that measurable range is 0.1 mR/h-200 mR/h, the sensitivity of γ is 90 cps/mR/h, dead time below 200 us, error of stability below ±10%. (authors)

Investigation of the dose rate dependency of the PAGAT gel dosimeter at low dose rates

International Nuclear Information System (INIS)

Zehtabian, M.; Faghihi, R.; Zahmatkesh, M.H.; Meigooni, A.S.; Mosleh-Shirazi, M.A.; Mehdizadeh, S.; Sina, S.; Bagheri, S.

2012-01-01

Medical physicists need dosimeters such as gel dosimeters capable of determining three-dimensional dose distributions with high spatial resolution. To date, in combination with magnetic resonance imaging (MRI), polyacrylamide gel (PAG) polymers are the most promising gel dosimetry systems. The purpose of this work was to investigate the dose rate dependency of the PAGAT gel dosimeter at low dose rates. The gel dosimeter was used for measurement of the dose distribution around a Cs-137 source from a brachytherapy LDR source to have a range of dose rates from 0.97 Gy h −1 to 0.06 Gy h −1 . After irradiation of the PAGAT gel, it was observed that the dose measured by gel dosimetry was almost the same at different distances (different dose rates) from the source, although the points nearer the source had been expected to receive greater doses. Therefore, it was suspected that the PAGAT gel is dose rate dependent at low dose rates. To test this further, three other sets of measurements were performed by placing vials containing gel at different distances from a Cs-137 source. In the first two measurements, several plastic vials were exposed to equal doses at different dose rates. An ionization chamber was used to measure the dose rate at each distance. In addition, three TLD chips were simultaneously irradiated in order to verify the dose to each vial. In the third measurement, to test the oxygen diffusion through plastic vials, the experiment was repeated again using plastic vials in a nitrogen box and glass vials. The study indicates that oxygen diffusion through plastic vials for dose rates lower than 2 Gy h −1 would affect the gel dosimeter response and it is suggested that the plastic vials or (phantoms) in an oxygen free environment or glass vials should be used for the dosimetry of low dose rate sources using PAGAT gel to avoid oxygen diffusion through the vials.

SU-F-J-45: Sparing Normal Tissue with Ultra-High Dose Rate in Radiation Therapy

Energy Technology Data Exchange (ETDEWEB)

Feng, Y [DCH Reg. Medical Center, Tuscaloosa, AL (United States)

2016-06-15

Purpose: To spare normal tissue by reducing the location uncertainty of a moving target, we proposed an ultra-high dose rate system and evaluated. Methods: High energy electrons generated with a linear accelerator were injected into a storage ring to be accumulated. The number of the electrons in the ring was determined based on the prescribed radiation dose. The dose was delivered within a millisecond, when an online imaging system found that the target was in the position that was consistent with that in a treatment plan. In such a short time period, the displacement of the target was negligible. The margin added to the clinical target volume (CTV) could be reduced that was evaluated by comparing of volumes between CTV and ITV in 14 cases of lung stereotactic body radiation therapy (SBRT) treatments. A design of the ultra-high dose rate system was evaluated based clinical needs and the recent developments of low energy (a few MeV) electron storage ring. Results: This design of ultra-high dose rate system was feasible based on the techniques currently available. The reduction of a target volume was significant by reducing the margin that accounted the motion of the target. ∼50% volume reduction of the internal target volume (ITV) could be achieved in lung SBRT treatments. Conclusion: With this innovation of ultra-high dose rate system, the margin of target is able to be significantly reduced. It will reduce treatment time of gating and allow precisely specified gating window to improve the accuracy of dose delivering.

Vascular training and endovascular practice in Europe

DEFF Research Database (Denmark)

Liapis, C.D.; Avgerinos, E.D.; Sillesen, H.

2009-01-01

specialties was distributed to a VS educator within 14 European countries. European Vascular and Endovascular Monitor (EVEM) data also were processed to correlate endovascular practice with training models. RESULTS: Fourteen questionnaires were gathered. Vascular training in Europe appears in 3 models: 1....... Mono-specialty (independence): 7 countries, 2. Subspecialty: 5 countries, 3. An existing specialty within general surgery: 2 countries. Independent compared to non-independent certification shortens overall training length (5.9 vs 7.9 years, p=0.006), while increasing overall training devoted......% respectively. Countries with independent vascular certification, despite their lower average endovascular index (procedures per 100,000 population), reported a higher growth rate of aortic endovascular procedures (VS independent 132% vs VS non-independent 87%), within a four-year period (2003-2007). Peripheral...

Evaluation of functioning of high dose rate brachytherapy at the Instituto Nacional do Cancer

International Nuclear Information System (INIS)

Guedes, Laura M.A.; Barreto, Rodrigo V.; Silva, Penha M.; Macedo, Afranio A.; Borges, Solange C.; Martinez, Valeria P.O.

2001-01-01

Quality control tests are very useful tools to assure the quality of patient's treatment. A daily control of the high dose rate micro selectron was performed based on the security parameters of the equipment and on the quickness of performance. The purpose of this report is to evaluate and to discuss the errors found during the first three years with the high dose rate brachytherapy, at the Instituto Nacional de Cancer. (author)

Dose-rate dependence of thermoluminescence response

International Nuclear Information System (INIS)

McKeever, S.W.S.; Chen, R.; Groom, P.J.; Durrani, S.A.

1980-01-01

The previously observed dose-rate effect of thermoluminescence in quartz at high dose-rates is given at theoretical formulation. Computer calculations simulating the experimental conditions yield similar results to the experimental ones. (orig.)

Development of a high sensitivity pinhole type gamma camera using semiconductors for low dose rate fields

Science.gov (United States)

Ueno, Yuichiro; Takahashi, Isao; Ishitsu, Takafumi; Tadokoro, Takahiro; Okada, Koichi; Nagumo, Yasushi; Fujishima, Yasutake; Yoshida, Akira; Umegaki, Kikuo

2018-06-01

We developed a pinhole type gamma camera, using a compact detector module of a pixelated CdTe semiconductor, which has suitable sensitivity and quantitative accuracy for low dose rate fields. In order to improve the sensitivity of the pinhole type semiconductor gamma camera, we adopted three methods: a signal processing method to set the discriminating level lower, a high sensitivity pinhole collimator and a smoothing image filter that improves the efficiency of the source identification. We tested basic performances of the developed gamma camera and carefully examined effects of the three methods. From the sensitivity test, we found that the effective sensitivity was about 21 times higher than that of the gamma camera for high dose rate fields which we had previously developed. We confirmed that the gamma camera had sufficient sensitivity and high quantitative accuracy; for example, a weak hot spot (0.9 μSv/h) around a tree root could be detected within 45 min in a low dose rate field test, and errors of measured dose rates with point sources were less than 7% in a dose rate accuracy test.

Construct Validity and Reliability of Structured Assessment of endoVascular Expertise in a Simulated Setting

DEFF Research Database (Denmark)

Bech, B; Lönn, L; Falkenberg, M

2011-01-01

Objectives To study the construct validity and reliability of a novel endovascular global rating scale, Structured Assessment of endoVascular Expertise (SAVE). Design A Clinical, experimental study. Materials Twenty physicians with endovascular experiences ranging from complete novices to highly....... Validity was analysed by correlating experience with performance results. Reliability was analysed according to generalisability theory. Results The mean score on the 29 items of the SAVE scale correlated well with clinical experience (R = 0.84, P ... with clinical experience (R = -0.53, P validity and reliability of assessment with the SAVE scale was high when applied to performances in a simulation setting with advanced realism. No ceiling effect...

Dose rate-dependent marrow toxicity of TBI in dogs and marrow sparing effect at high dose rate by dose fractionation.

Science.gov (United States)

Storb, R; Raff, R F; Graham, T; Appelbaum, F R; Deeg, H J; Schuening, F G; Sale, G; Seidel, K

1999-01-01

We evaluated the marrow toxicity of 200 and 300 cGy total-body irradiation (TBI) delivered at 10 and 60 cGy/min, respectively, in dogs not rescued by marrow transplant. Additionally, we compared toxicities after 300 cGy fractionated TBI (100 cGy fractions) to that after single-dose TBI at 10 and 60 cGy/min. Marrow toxicities were assessed on the basis of peripheral blood cell count changes and mortality from radiation-induced pancytopenia. TBI doses studied were just below the dose at which all dogs die despite optimal support. Specifically, 18 dogs were given single doses of 200 cGy TBI, delivered at either 10 (n=13) or 60 (n=5) cGy/min. Thirty-one dogs received 300 cGy TBI at 10 cGy/min, delivered as either single doses (n=21) or three fractions of 100 cGy each (n=10). Seventeen dogs were given 300 cGy TBI at 60 cGy/min, administered either as single doses (n=5) or three fractions of 100 cGy each (n=10). Within the limitations of the experimental design, three conclusions were drawn: 1) with 200 and 300 cGy single-dose TBI, an increase of dose rate from 10 to 60 cGy/min, respectively, caused significant increases in marrow toxicity; 2) at 60 cGy/min, dose fractionation resulted in a significant decrease in marrow toxicities, whereas such a protective effect was not seen at 10 cGy/min; and 3) with fractionated TBI, no significant differences in marrow toxicity were seen between dogs irradiated at 60 and 10 cGy/min. The reduced effectiveness of TBI when a dose of 300 cGy was divided into three fractions of 100 cGy or when dose rate was reduced from 60 cGy/min to 10 cGy/min was consistent with models of radiation toxicity that allow for repair of sublethal injury in DNA.

Utility of gadolinium as a contrast medium in endovascular therapeutic procedures; Utilidad del gadolinio como medio de contraste en procedimientos terapeuticos endovasculares

Energy Technology Data Exchange (ETDEWEB)

Reyes, R.; Pardo, M. D.; Gorriz, E.; Gallardo, L. (Hospital de Gran Canaria Dr. Negrin); Carreira, J. M. (Universidad de Santiago de Compostela)

2001-07-01

To assess the utility of gadolinium associated with CO{sub 2}, as a contrast medium in angiographic studies related to endovascular therapeutic procedures in patients with suboptimal renal function. Between January 2000 and June 2001, endovascular treatments using CO{sub 2} and gadolinium as contrast medium were performed in 10 patients presenting renal function deterioration (creatinine>1.5 mg/ml). A mean dose of 42 ml of gadolinium was administered. The images acquired in diagnostic and therapeutic studied were satisfactory in every case. There was no evidence of significant increases in the previous urea and creatine levels when measured 24, 48 and 72 hours after the procedure. In combination with CO{sub 2} gadolinium is a useful contrast medium for endovascular therapeutic procedures in patients with suboptimal renal function. (Author) 21 refs.

Development of a high precision dosimetry system for the measurement of surface dose rate distribution for eye applicators

Energy Technology Data Exchange (ETDEWEB)

Eichmann, Marion; Fluehs, Dirk; Spaan, Bernhard [Fakultaet Physik, Technische Universitaet Dortmund, D 44221 Dortmund (Germany); Klinische Strahlenphysik, Universitaetsklinikum Essen, D 45122 Essen (Germany); Fakultaet Physik, Technische Universitaet Dortmund, D 44221 Dortmund (Germany)

2009-10-15

Purpose: The therapeutic outcome of the therapy with ophthalmic applicators is highly dependent on the application of a sufficient dose to the tumor, whereas the dose applied to the surrounding tissue needs to be minimized. The goal for the newly developed apparatus described in this work is the determination of the individual applicator surface dose rate distribution with a high spatial resolution and a high precision in dose rate with respect to time and budget constraints especially important for clinical procedures. Inhomogeneities of the dose rate distribution can be detected and taken into consideration for the treatment planning. Methods: In order to achieve this, a dose rate profile as well as a surface profile of the applicator are measured and correlated with each other. An instrumental setup has been developed consisting of a plastic scintillator detector system and a newly designed apparatus for guiding the detector across the applicator surface at a constant small distance. It performs an angular movement of detector and applicator with high precision. Results: The measurements of surface dose rate distributions discussed in this work demonstrate the successful operation of the measuring setup. Measuring the surface dose rate distribution with a small distance between applicator and detector and with a high density of measuring points results in a complete and gapless coverage of the applicator surface, being capable of distinguishing small sized spots with high activities. The dosimetrical accuracy of the measurements and its analysis is sufficient (uncertainty in the dose rate in terms of absorbed dose to water is <7%), especially when taking the surgical techniques in positioning of the applicator on the eyeball into account. Conclusions: The method developed so far allows a fully automated quality assurance of eye applicators even under clinical conditions. These measurements provide the basis for future calculation of a full 3D dose rate

Development of a high precision dosimetry system for the measurement of surface dose rate distribution for eye applicators.

Science.gov (United States)

Eichmann, Marion; Flühs, Dirk; Spaan, Bernhard

2009-10-01

The therapeutic outcome of the therapy with ophthalmic applicators is highly dependent on the application of a sufficient dose to the tumor, whereas the dose applied to the surrounding tissue needs to be minimized. The goal for the newly developed apparatus described in this work is the determination of the individual applicator surface dose rate distribution with a high spatial resolution and a high precision in dose rate with respect to time and budget constraints especially important for clinical procedures. Inhomogeneities of the dose rate distribution can be detected and taken into consideration for the treatment planning. In order to achieve this, a dose rate profile as well as a surface profile of the applicator are measured and correlated with each other. An instrumental setup has been developed consisting of a plastic scintillator detector system and a newly designed apparatus for guiding the detector across the applicator surface at a constant small distance. It performs an angular movement of detector and applicator with high precision. The measurements of surface dose rate distributions discussed in this work demonstrate the successful operation of the measuring setup. Measuring the surface dose rate distribution with a small distance between applicator and detector and with a high density of measuring points results in a complete and gapless coverage of the applicator surface, being capable of distinguishing small sized spots with high activities. The dosimetrical accuracy of the measurements and its analysis is sufficient (uncertainty in the dose rate in terms of absorbed dose to water is <7%), especially when taking the surgical techniques in positioning of the applicator on the eyeball into account. The method developed so far allows a fully automated quality assurance of eye applicators even under clinical conditions. These measurements provide the basis for future calculation of a full 3D dose rate distribution, which then can be used as input for

Gamma dose rate effect on JFET transistors

International Nuclear Information System (INIS)

Assaf, J.

2011-04-01

The effect of Gamma dose rate on JFET transistors is presented. The irradiation was accomplished at the following available dose rates: 1, 2.38, 5, 10 , 17 and 19 kGy/h at a constant dose of 600 kGy. A non proportional relationship between the noise and dose rate in the medium range (between 2.38 and 5 kGy/h) was observed. While in the low and high ranges, the noise was proportional to the dose rate as the case of the dose effect. This may be explained as follows: the obtained result is considered as the yield of a competition between many reactions and events which are dependent on the dose rate. At a given values of that events parameters, a proportional or a non proportional dose rate effects are generated. No dependence effects between the dose rate and thermal annealing recovery after irradiation was observed . (author)

High-dose-rate interstitial brachytherapy for the treatment of penile carcinoma

Energy Technology Data Exchange (ETDEWEB)

Petera, J.; Odrazka, K.; Zouhar, M.; Bedrosova, J.; Dolezel, M. [Dept. of Oncology and Radiotherapy, Charles Univ. Medical School and Teaching Hospital, Hradec Kralove (Czech Republic)

2004-02-01

Background: interstitial low-dose-rate (LDR) brachytherapy allows conservative treatment of T1-T2 penile carcinoma. High-dose-rate (HDR) is often considered to be dangerous for interstitial implants because of a higher risk of complications, but numerous reports suggest that results may be comparable to LDR. Nevertheless, there are no data in the literature available regarding HDR interstitial brachytherapy for carcinoma of the penis. Case report: a 64-year-old man with T1 NO MO epidermoid carcinoma of the glans is reported. Interstitial HDR brachytherapy was performed using the stainless hollow needle technique and a breast template for fixation and good geometry. The dose delivered was 18 x 3 Gy twice daily. Results: after 232 days from brachytherapy, the patient was without any evidence of the tumor, experienced no serious radiation-induced complications, and had a fully functional organ. Conclusion: HDR interstitial brachytherapy is feasible in selected case of penis carcinoma, when careful planning and small single fractions are used. (orig.)

Conditioned instrumental behaviour in the rat: Effects of prenatal irradiation with various low dose-rate doses

International Nuclear Information System (INIS)

Klug, H.

1986-01-01

4 groups of rats of the Wistar-strain were subjected to γ-irradiation on the 16th day of gestation. 5 rats received 0,6 Gy low dose rate irradiation, 5 animals received 0,9 Gy low dose and 6 high dose irradiation, 3 females were shamirradiated. The male offspring of these 3 irradiation groups and 1 control group were tested for locomotor coordination on parallel bars and in a water maze. The female offspring were used in an operant conditioning test. The locomotor test showed slight impairment of locomotor coordination in those animals irradiated with 0,9 Gy high dose rate. Swimming ability was significantly impaired by irradiation with 0,9 Gy high dose rate. Performance in the operant conditioning task was improved by irradiation with 0,9 Gy both low and high dose rate. The 0,9 Gy high dose rate group learned faster than all the other groups. For the dose of 0,9 Gy a significant dose rate effect could be observed. For the dose of 0,6 Gy a similar tendency was observed, differences between 0,6 Gy high and low dose rate and controls not being significant. (orig./MG) [de

High dose rate versus low dose rate brachytherapy for oral cancer--a meta-analysis of clinical trials.

Directory of Open Access Journals (Sweden)

Zhenxing Liu

Full Text Available To compare the efficacy and safety of high dose rate (HDR and low dose rate (LDR brachytherapy in treating early-stage oral cancer.A systematic search of MEDLINE, EMBASE and Cochrane Library databases, restricted to English language up to June 1, 2012, was performed to identify potentially relevant studies.Only randomized controlled trials (RCT and controlled trials that compared HDR to LDR brachytherapy in treatment of early-stage oral cancer (stages I, II and III were of interest.Two investigators independently extracted data from retrieved studies and controversies were solved by discussion. Meta-analysis was performed using RevMan 5.1. One RCT and five controlled trials (607 patients: 447 for LDR and 160 for HDR met the inclusion criteria. The odds ratio showed no statistically significant difference between LDR group and HDR group in terms of local recurrence (OR = 1.12, CI 95% 0.62-2.01, overall mortality (OR = 1.01, CI 95% 0.61-1.66 and Grade 3/4 complications (OR = 0.86, CI 95% 0.52-1.42.This meta-analysis indicated that HDR brachytherapy was a comparable alternative to LDR brachytherapy in treatment of oral cancer. HDR brachytherapy might become a routine choice for early-stage oral cancer in the future.

Bladder–Rectum Spacer Balloon in High-Dose-Rate Brachytherapy in Cervix Carcinoma

Energy Technology Data Exchange (ETDEWEB)

Rai, Bhavana [Department of Radiotherapy and Oncology, Regional Cancer Centre, Postgraduate Institute of Medical Education and Research, Chandigarh (India); Patel, Firuza D., E-mail: firuzapatel@gmail.com [Department of Radiotherapy and Oncology, Regional Cancer Centre, Postgraduate Institute of Medical Education and Research, Chandigarh (India); Chakraborty, Santam; Sharma, Suresh C.; Kapoor, Rakesh [Department of Radiotherapy and Oncology, Regional Cancer Centre, Postgraduate Institute of Medical Education and Research, Chandigarh (India); Aprem, Abi Santhosh [Corporate R and D Division, HLL Lifecare Limited, Karamana, Trivandrum (India)

2013-04-01

Purpose: To compare bladder and rectum doses with the use of a bladder–rectum spacer balloon (BRSB) versus standard gauze packing in the same patient receiving 2 high-dose-rate intracavitary brachytherapy fractions. Methods and Materials: This was a randomized study to compare the reduction in bladder and rectum doses with the use of a BRSB compared with standard gauze packing in patients with carcinoma of the cervix being treated with high-dose-rate intracavitary brachytherapy. The patients were randomized between 2 arms. In arm A, vaginal packing was done with standard gauze packing in the first application, and BRSB was used in the second application. Arm B was the reverse of arm A. The International Commission for Radiation Units and Measurement (ICRU) point doses and doses to 0.1-cm{sup 3}, 1-cm{sup 3}, 2-cm{sup 3}, 5-cm{sup 3}, and 10-cm{sup 3} volumes of bladder and rectum were compared. The patients were also subjectively assessed for the ease of application and the time taken for application. Statistical analysis was done using the paired t test. Results: A total of 43 patients were enrolled; however, 3 patients had to be excluded because the BRSB could not be inserted owing to unfavorable local anatomy. Thus 40 patients (80 plans) were evaluated. The application was difficult in 3 patients with BRSB, and in 2 patients with BRSB the application time was prolonged. There was no significant difference in bladder doses to 0.1 cm{sup 3}, 1 cm{sup 3}, 2 cm{sup 3}, 5 cm{sup 3}, and 10 cm{sup 3} and ICRU bladder point. Statistically significant dose reductions to 0.1-cm{sup 3}, 1-cm{sup 3}, and 2-cm{sup 3} volumes for rectum were observed with the BRSB. No significant differences in 5-cm{sup 3} and 10-cm{sup 3} volumes and ICRU rectum point were observed. Conclusion: A statistically significant dose reduction was observed for small high-dose volumes in rectum with the BRSB. The doses to bladder were comparable for BRSB and gauze packing. Transparent balloons of

Dose rate constants for new dose quantities

International Nuclear Information System (INIS)

Tschurlovits, M.; Daverda, G.; Leitner, A.

1992-01-01

Conceptual changes and new quantities made is necessary to reassess dose rate quantities. Calculations of the dose rate constant were done for air kerma, ambient dose equivalent and directional dose equivalent. The number of radionuclides is more than 200. The threshold energy is selected as 20 keV for the dose equivalent constants. The dose rate constant for the photon equivalent dose as used mainly in German speaking countries as a temporary quantity is also included. (Author)

Open surgery versus endovascular approach in treatment of extracranial carotid artery aneurysms.

Science.gov (United States)

Ni, Leng; Weng, Huiling; Pu, Zuo; Zheng, Yuehong; Liu, Bao; Ye, Wei; Zeng, Rong; Liu, Changwei

2018-05-01

The objective of this study was to investigate and to compare the early and long-term results of open surgery with endovascular intervention in the treatment of extracranial carotid artery aneurysms (ECCAs). A retrospective review of patients diagnosed with ECCAs who underwent open surgical or endovascular treatment from 1997 to 2017 was performed. Clinical characteristics, aneurysm profile, and treatment outcomes were recorded. Early results (open surgery; endovascular repair was performed on 16 patients (33.3%). The 30-day stroke or transient ischemic attack rate was not significantly different between the open group (6.3% [2/32]) and the endovascular group (0% [0/16]; P = .307). Cranial nerve injuries occurred in eight patients in the open group (25%) and in no patient in the endovascular group (0%; P = .029). Median length of stay was significantly longer in the open group than in the endovascular group (20 vs 14 days, respectively; P = .013). Median follow-up was 46 months (range, 0-20 years), and no aneurysm-related death occurred during this period. Overall survival rates at 5 years were 88.7% (standard error [SE], 0.08) in the open group and 91.7% (SE, 0.08) in the endovascular group (P = .319; log-rank, .992). For the same time interval, stroke-free survival rates were 85.2% (SE, 0.10) in the open group and 92.2% (SE, 0.07) in the endovascular group (P = .653; log-rank, .201). One patient (1/28 [3.6%]) in the open group and two patients (2/16 [12.5%]) in the endovascular group underwent endovascular reinterventions because of restenosis during the follow-up period. Reintervention-free survival rates were 90.9% in the open group (SE, 0.09) and 69.2% in the endovascular group (SE, 0.21; P = .082; log-rank, 3.016). In this single-institutional experience, both operative and endovascular interventions for ECCAs provided acceptable early and 5-year results. The endovascular approach had significantly less cranial nerve injury and shorter length of

Radiobiological response to ultra-short pulsed megavoltage electron beams of ultra-high pulse dose rate.

Science.gov (United States)

Beyreuther, Elke; Karsch, Leonhard; Laschinsky, Lydia; Leßmann, Elisabeth; Naumburger, Doreen; Oppelt, Melanie; Richter, Christian; Schürer, Michael; Woithe, Julia; Pawelke, Jörg

2015-08-01

In line with the long-term aim of establishing the laser-based particle acceleration for future medical application, the radiobiological consequences of the typical ultra-short pulses and ultra-high pulse dose rate can be investigated with electron delivery. The radiation source ELBE (Electron Linac for beams with high Brilliance and low Emittance) was used to mimic the quasi-continuous electron beam of a clinical linear accelerator (LINAC) for comparison with electron pulses at the ultra-high pulse dose rate of 10(10) Gy min(-1) either at the low frequency of a laser accelerator or at 13 MHz avoiding effects of prolonged dose delivery. The impact of pulse structure was analyzed by clonogenic survival assay and by the number of residual DNA double-strand breaks remaining 24 h after irradiation of two human squamous cell carcinoma lines of differing radiosensitivity. The radiation response of both cell lines was found to be independent from electron pulse structure for the two endpoints under investigation. The results reveal, that ultra-high pulse dose rates of 10(10) Gy min(-1) and the low repetition rate of laser accelerated electrons have no statistically significant influence (within the 95% confidence intervals) on the radiobiological effectiveness of megavoltage electrons.

Monte Carlo dosimetry of the IRAsource high dose rate 192Ir brachytherapy source

International Nuclear Information System (INIS)

Sarabiasl, Akbar; Ayoobian, Navid; Jabbari, Iraj; Poorbaygi, Hossein; Javanshir, Mohammad Reza

2016-01-01

High-dose-rate (HDR) brachytherapy is a common method for cancer treatment in clinical brachytherapy. Because of the different source designs, there is a need for specific dosimetry data set for each HDR model. The purpose of this study is to obtain detailed dose rate distributions in water phantom for a first prototype HDR 192 Ir brachytherapy source model, IRAsource, and compare with the other published works. In this study, Monte Carlo N-particle (MCNP version 4C) code was used to simulate the dose rate distributions around the HDR source. A full set of dosimetry parameters reported by the American Association of Physicists in Medicine Task Group No. 43U1 was evaluated. Also, the absorbed dose rate distributions in water, were obtained in an along-away look-up table. The dose rate constant, Λ, of the IRAsource was evaluated to be equal to 1.112 ± 0.005 cGy h −1 U −1 . The results of dosimetry parameters are presented in tabulated and graphical formats and compared with those reported from other commercially available HDR 192 Ir sources, which are in good agreement. This justifies the use of specific data sets for this new source. The results obtained in this study can be used as input data in the conventional treatment planning systems.

Pre-installation empirical testing of room shielding for high dose rate remote afterloaders

International Nuclear Information System (INIS)

Klein, E.E.; Grigsby, P.W.; Williamson, J.F.; Meigooni, A.S.

1993-01-01

PURPOSE: Many facilities are acquiring high dose rate remote afterloading units. It is economical that these units be placed in existing shielded teletherapy rooms. Scatter-radiation barriers marginally protect uncontrolled areas from a high dose rate source especially in a room that houses a non-dynamic Cobalt-60 unit. In addition the exact thickness and material composition of the barriers are unknown and therefore, a calculation technique may give misleading results. Also, it would be impossible to evaluate an entire wall barrier by taking isolated core samples in order to assist in the calculations. A quick and inexpensive measurement of dose equivalent using a rented high activity 192Ir source evaluates the barriers and locates shielding deficiencies. METHODS AND MATERIALS: We performed transmission calculations for primary and scattered radiation based on National Council on Radiation Protection and Measurements Reports 49 and 51, respectively. We then rented a high activity 21.7 Ci (8.03 x 10(11) Bq) Ir-192 source to assess our existing teletherapy room shielding for adequacy and voids. This source was placed at the proposed location for clinical high dose rate treatment and measurements were performed. RESULTS: No deficiencies were found in controlled areas surrounding the room, but large differences were found between the calculated and measured values. Our survey located a region in the uncontrolled area above the room requiring augmented shielding which was not predicted by the calculations. A canopy shield was designed to potentially augment the shielding in the ceiling direction. CONCLUSION: Pre-installation testing by measurement is an invaluable method for locating shielding deficiencies and avoiding unnecessary enhancement of shielding particularly when there is lack of information of the inherent shielding

Development of Real-Time Measurement of Effective Dose for High Dose Rate Neutron Fields

CERN Document Server

Braby, L A; Reece, W D

2003-01-01

Studies of the effects of low doses of ionizing radiation require sources of radiation which are well characterized in terms of the dose and the quality of the radiation. One of the best measures of the quality of neutron irradiation is the dose mean lineal energy. At very low dose rates this can be determined by measuring individual energy deposition events, and calculating the dose mean of the event size. However, at the dose rates that are normally required for biology experiments, the individual events can not be separated by radiation detectors. However, the total energy deposited in a specified time interval can be measured. This total energy has a random variation which depends on the size of the individual events, so the dose mean lineal energy can be calculated from the variance of repeated measurements of the energy deposited in a fixed time. We have developed a specialized charge integration circuit for the measurement of the charge produced in a small ion chamber in typical neutron irradiation exp...

MRI dosimetry using an echo-quotient technique for high dose rate brachytherapy

International Nuclear Information System (INIS)

Ansbacher, W.

1996-01-01

MRI gel dosimetry is a relatively new technique that has many advantages over conventional methods, and is particularly suited to High Dose Rate (HDR) Brachytherapy. The dosimeter has high spatial resolution and a water-equivalent response over a wide range of photon energies. Because it is an integrating dosimeter, it allows for efficient mapping of the dynamically-produced distributions from an HDR source. As an example of this technique, the dose response, which is calibrated in terms of the change in spin-spin relaxation time, has been used to investigate the anisotropy of an HDR source. (author). 1 fig

Endovascular repair of para-anastomotic aortoiliac aneurysms.

LENUS (Irish Health Repository)

Tsang, Julian S

2009-11-01

The purpose of this study is to evaluate the use of endovascular stent grafts in the treatment of para-anastomotic aneurysms (PAAs) as an alternative to high-risk open surgical repair. We identified all patients with previous open aortic aneurysm repair who underwent infrarenal endovascular aneurysm repair (EVAR) at our institution from June 1998 to April 2007. Patient demographics, previous surgery, and operative complications were recorded. One hundred forty-eight patients underwent EVAR during the study period and 11 patients had previous aortic surgery. Of these 11 redo patients, the mean age was 62 years at initial surgery and 71 years at EVAR. All patients were male. Initial open repair was for rupture in five (45%) patients. The average time between initial and subsequent reintervention was 9 years. All patients were ASA Grade III or IV. Fifty-five percent of the PAAs involved the iliac arteries, 36% the abdominal aorta, and 9% were aortoiliac. Ten patients had endovascular stent-grafts inserted electively, and one patient presented with a contained leak. Aorto-uni-iliac stent-grafts were deployed in seven patients, and bifurcated stent-grafts in four patients. A 100% successful deployment rate was achieved. Perioperative mortality was not seen and one patient needed surgical reintervention to correct an endoleak. Endovascular repair of PAAs is safe and feasible. It is a suitable alternative and has probably now become the treatment of choice in the management of PAAs.

Endovascular treatment of intracranial arteriovenous malformations

International Nuclear Information System (INIS)

Seruga, T.

2002-01-01

Background. The aim of the study was the introduction of endovascular interventional treatment of cerebral arteriovenous malformations (AVM) with superselective embolization with cyanoacrylic polymerisation agent. Case reports. Endovascular embolization was performed in five patients with cerebral AVMs. Three of these patients were presented with intracerebral haemathomas whereas in other two patients, cerebral AVM was an incidental finding. Superselective catheterisation of AVMs was performed and acrylic glue was selectively injected into the nidus. Conclusions. Control cerebral angiography after embolization of AVM showed different results. In one patient, AVM was totally occluded after three sessions and in second case AVM was occluded in a single session. The rate of occlusion in other two cases was estimated between 70% in 80%. Both of these two patients underwent surgery. One patient is still in the process of treatment. Endovascular treatment of cerebral AVMs with superselective embolization with liquid cyanoacrilyc adhesive agent is a safe and effective alternative treatment paths next to microsurgery. Endovascular treatment in combination with radiosurgery could become the method of choice in the therapy of cerebral AVMs in the future. (author)

Actual review of diagnostics and endovascular therapy of intracranial arterial stenoses; Diagnostik und endovaskulaere Therapie intrakranieller arterieller Stenosen

Energy Technology Data Exchange (ETDEWEB)

Gizewski, E.R. [Universitaetsklinikum Essen (Germany). Inst. fuer Diagnostische und Interventionelle Radiologie und Neuroradiologie; Weber, R. [Universitaetsklinikum Essen (Germany). Klinik fuer Neurologie; Forsting, M. [Universitaetsklinikum Giessen und Marburg, Giessen (Germany). Abt. fuer Neuroradiologie

2011-02-15

Approximately 6 - 50 % of all ischemic strokes are caused by intracranial arterial stenosis (IAS). Despite medical prevention, patients with symptomatic IAS have a high annual risk for recurrent ischemic stroke of about 12 %, and up to 19 % in the case of high-grade IAS ({>=} 70 %). Digital subtraction angiography remains the gold standard for the diagnosis and grading of IAS. However, noninvasive imaging techniques including CT angiography, MR angiography, or transcranial Doppler and duplex ultrasound examinations are used in the clinical routine to provide additional information about the brain structure and hemodynamic. However, for technical reasons, the grading of stenoses is sometimes difficult and inaccurate. To date, aspirin is recommended as the treatment of choice in the prevention of recurrent ischemic stroke in patients with IAS. IAS patients who suffer a recurrent ischemic stroke or transient ischemic attack while taking aspirin can be treated with endovascular stenting or angioplasty in specialized centers. The periprocedural complication rate of these endovascular techniques is about 2 - 7 % at experienced neuro-interventional centers. The rate of re-stenosis is reported between 10 and 40 % depending on patient age and stenosis location. Further randomized studies comparing medical secondary prevention and endovascular therapy are currently being performed. With regard to the improvement of endovascular methods and lower complication rates, the indication for endovascular therapy in IAS could be broadened especially for stenosis in the posterior circulation. (orig.)

Routine quality control of high dose rate brachytherapy equipment

International Nuclear Information System (INIS)

Guzman Calcina, Carmen S.; Almeida, Adelaide de; Rocha, Jose R. Oliveira

2001-01-01

A Quality Assurance program should be installed also for High Dose Rate brachytherapy, in the order to achieve a correct dose administration to the patient and for the safety to those involved directly with the treatment. The work presented here has the following purposes: Analyze the types of equipment tests presented by the official protocols (TG40, TG56 e ARCAL XXX), evaluate the brachytherapy routine tests of protocols from various national and international radiotherapy services and compare the latter with those presented in the official protocols. As a result, we conclude the following: TG56 presents a higher number of tests when compared to the other official protocols and most of the tests presented by the analyzed services are present in TG56. A suggestion for a basic protocol is presented, emphasizing the periodicity and tolerance level of each of the tests. (author)

Radiation safety program in a high dose rate brachytherapy facility

International Nuclear Information System (INIS)

Rodriguez, L.V.; Hermoso, T.M.; Solis, R.C.

2001-01-01

The use of remote afterloading equipment has been developed to improve radiation safety in the delivery of treatment in brachytherapy. Several accidents, however, have been reported involving high dose-rate brachytherapy system. These events, together with the desire to address the concerns of radiation workers, and the anticipated adoption of the International Basic Safety Standards for Protection Against Ionizing Radiation (IAEA, 1996), led to the development of the radiation safety program at the Department of Radiotherapy, Jose R. Reyes Memorial Medical Center and at the Division of Radiation Oncology, St. Luke's Medical Center. The radiation safety program covers five major aspects: quality control/quality assurance, radiation monitoring, preventive maintenance, administrative measures and quality audit. Measures for evaluation of effectiveness of the program include decreased unnecessary exposures of patients and staff, improved accuracy in treatment delivery and increased department efficiency due to the development of staff vigilance and decreased anxiety. The success in the implementation required the participation and cooperation of all the personnel involved in the procedures and strong management support. This paper will discuss the radiation safety program for a high dose rate brachytherapy facility developed at these two institutes which may serve as a guideline for other hospitals intending to install a similar facility. (author)

Recommendations of the EVA GEC ESTRO Working Group: prescribing, recording, and reporting in endovascular brachytherapy. Quality assurance, equipment, personnel and education

International Nuclear Information System (INIS)

Poetter, Richard; Limbergen, Erik van; Dries, Wim; Popowski, Youri; Coen, Veronique; Fellner, Claudia; Georg, Dietmar; Kirisits, Christian; Levendag, Peter; Marijnissen, Hans; Marsiglia, Hugo; Mazeron, Jean-Jaques; Pokrajac, Boris; Scalliet, Pierre; Tamburini, Vittorio

2001-01-01

Endovascular brachytherapy is a new, rapidly growing field of interest in radiotherapy for the prevention of neointimal hyperplasia after angioplasty in both coronary and peripheral arteries. Many physics aspects of these treatments have already been addressed in the report of the American Association of Physicists in Medicine task group on 'Intravascular brachytherapy', but up to now there are no generally accepted recommendations for recording and reporting radiation doses and volumes. The terminology to be used by all individuals involved in such treatments (radiation oncologists, physicists, and interventionalists) is not clearly defined. The Endovascular Groupe Europeen de Curietherapie/European Society for Therapeutic Radiology and Oncology Working Group in this document presents recommendations for a common language for general use in endovascular brachytherapy. This proposal addresses general terms and concepts for target and dose specification as well as detailed recommendations for dose prescription, recording and reporting in endovascular brachytherapy for both peripheral and coronary arteries. Additionally, quality assurance and radiation safety aspects are briefly addressed, as are aspects related to equipment, personnel, and training and education related to endovascular brachytherapy

Dose rate correction in medium dose rate brachytherapy for carcinoma cervix

International Nuclear Information System (INIS)

Patel, F.D.; Negi, P.S.; Sharma, S.C.; Kapoor, R.; Singh, D.P.; Ghoshal, S.

1998-01-01

Purpose: To establish the magnitude of brachytherapy dose reduction required for stage IIB and III carcinoma cervix patients treated by external radiation and medium dose rate (MDR) brachytherapy at a dose rate of 220±10 cGy/h at point A.Materials and methods: In study-I, at the time of MDR brachytherapy application at a dose rate of 220±10 cGy/h at point A, patients received either 3060 cGy, a 12.5% dose reduction (MDR-12.5), or 2450 cGy, a 30% dose reduction (MDR-30), to point A and they were compared to a group of previously treated LDR patients who received 3500 cGy to point A at a dose rate of 55-65 cGy/h. Study-II was a prospective randomized trial and patients received either 2450 cGy, a 30% dose reduction (MDR-II (30)) or 2800 cGy, a 20% dose reduction (MDR-II (20)), at point A. Patients were evaluated for local control of disease and morbidity. Results: In study-I the 5-year actuarial local control rate in the MDR-30 and MDR-12.5 groups was 71.7±10% and 70.5±10%, respectively, compared to 63.4±10% in the LDR group. However, the actuarial morbidity (all grades) in the MDR-12.5 group was 58.5±14% as against 34.9±9% in the LDR group (P 3 developed complication as against 62.5% of those receiving a rectal BED of (140 3 (χ 2 =46.43; P<0.001). Conclusion: We suggest that at a dose rate of 220±10 cGy/h at point A the brachytherapy dose reduction factor should be around 30%, as suggested by radiobiological data, to keep the morbidity as low as possible without compromising the local control rates. (Copyright (c) 1998 Elsevier Science B.V., Amsterdam. All rights reserved.)

Intracavitary after loading techniques, advantages and disadvantages with high and low dose-rate methods

International Nuclear Information System (INIS)

Walstam, Rune

1980-01-01

Even though suggested as early as 1903, it is only when suitable sealed gamma sources became available, afterloading methods could be developed for interstitial as well as intracavitary work. Manual afterloading technique can be used only for low dose rate irradiation, while remote controlled afterloading technique can be used for both low and high dose-rate irradiation. Afterloading units used at the Karolinska Institute, Stockholm, are described, and experience of their use is narrated briefly. (M.G.B.)

Combination of high-dose rate brachytherapy and external beam radiotherapy for the treatment of advanced scalp angiosarcoma - case report

International Nuclear Information System (INIS)

Gentil, Andre Cavalcanti; Lima Junior, Carlos Genesio Bezerra; Soboll, Danyel Scheidegger; Novaes, Paulo Eduardo R.S.; Pereira, Adelino Jose; Pellizon, Antonio Carlos Assis

2001-01-01

The authors report a case of a patient with an extensive angiosarcoma of the scalp that was submitted only to radiotherapy with a combination of orthovoltage roentgentherapy and high-dose rate brachytherapy, using a mould. The clinical and technical features as well as the therapeutic outcome are presented, and the usefulness and peculiarities of high-dose rate brachytherapy for this particular indication is discussed. A comparative analysis of the difficulties and limitations of employing low-dose rate brachytherapy is also presented. The authors concluded that high-dose rate brachytherapy might be an useful, practical and safe option to treat neoplastic lesions of the scalp, and an alternative treatment to electrontherapy. (author)

Toward endobronchial Ir-192 high-dose-rate brachytherapy therapeutic optimization

International Nuclear Information System (INIS)

Gay, H A; Allison, R R; Downie, G H; Mota, H C; Austerlitz, C; Jenkins, T; Sibata, C H

2007-01-01

A number of patients with lung cancer receive either palliative or curative high-dose-rate (HDR) endobronchial brachytherapy. Up to a third of patients treated with endobronchial HDR die from hemoptysis. Rather than accept hemoptysis as an expected potential consequence of HDR, we have calculated the radial dose distribution for an Ir-192 HDR source, rigorously examined the dose and prescription points recommended by the American Brachytherapy Society (ABS), and performed a radiobiological-based analysis. The radial dose rate of a commercially available Ir-192 source was calculated with a Monte Carlo simulation. Based on the linear quadratic model, the estimated palliative, curative and blood vessel rupture radii from the center of an Ir-192 source were obtained for the ABS recommendations and a series of customized HDR prescriptions. The estimated radius at risk for blood vessel perforation for the ABS recommendations ranges from 7 to 9 mm. An optimized prescription may in some situations reduce this radius to 4 mm. The estimated blood perforation radius is generally smaller than the palliative radius. Optimized and individualized endobronchial HDR prescriptions are currently feasible based on our current understanding of tumor and normal tissue radiobiology. Individualized prescriptions could minimize complications such as fatal hemoptysis without sacrificing efficacy. Fiducial stents, HDR catheter centering or spacers and the use of CT imaging to better assess the relationship between the catheter and blood vessels promise to be useful strategies for increasing the therapeutic index of this treatment modality. Prospective trials employing treatment optimization algorithms are needed

Physics and quality assurance for high dose rate brachytherapy

International Nuclear Information System (INIS)

Anderson, Lowell L.

1995-01-01

Purpose: To review the physical aspects of high dose rate (HDR) brachytherapy, including commissioning and quality assurance, source calibration and dose distribution measurements, and treatment planning methods. Following the introduction of afterloading in brachytherapy, development efforts to make it 'remote' culminated in 1964 with the near-simultaneous appearance of remote afterloaders in five major medical centers. Four of these machines were 'high dose rate', three employing 60Co and one (the GammaMed) using a single, cable-mounted 192Ir source. Stepping-motor source control was added to the GammaMed in 1974, making it the precursor of modern remote afterloaders, which are now suitable for interstitial as well as intracavitary brachytherapy by virtue of small source-diameter and indexer-accessed multiple channels. Because the 192Ir sources currently used in HDR remote afterloaders are supplied at a nominal air-kerma strength of 11.4 cGy cm2 s-1 (10 Ci), are not collimated in clinical use, and emit a significant fraction (15%) of photons at energies greater than 600 keV, shielding and facility design must be undertaken as carefully and thoroughly as for external beam installations. Licensing requirements of regulatory agencies must be met with respect both to maximum permissible dose limits and to the existence and functionality of safety devices (door interlocks, radiation monitors, etc.). Commissioning and quality assurance procedures that must be documented for HDR remote afterloading relate to (1) machine, applicator, guide-tube, and facility functionality checks, (2) source calibration, (3) emergency response readiness, (4) planning software evaluation, and (5) independent checks of clinical dose calculations. Source calibration checks must be performed locally, either by in-air measurement of air kerma strength or with a well ionization chamber calibrated (by an accredited standards laboratory) against an in-air measurement of air kerma strength for the

Perioperative Interstitial High-Dose-Rate Brachytherapy for the Treatment of Recurrent Keloids

DEFF Research Database (Denmark)

Jiang, Ping; Baumann, René; Dunst, Jürgen

2016-01-01

PURPOSE: To prospectively evaluate high-dose-rate brachytherapy in the treatment of therapy-resistant keloids and report first results, with emphasis on feasibility and early treatment outcome. METHODS AND MATERIALS: From 2009 to 2014, 24 patients with 32 recurrent keloids were treated with immed...

On-Line High Dose-rate Gamma Irradiation Test of the Profibus/DP module

Energy Technology Data Exchange (ETDEWEB)

Cho, Jai Wan; Choi, Young Soo; Kim, Chang Hoi; Koo, In Soo; Hong, Seok Boong [Korea Atomic Energy Research Institute, Daejeon (Korea, Republic of)

2009-05-15

The field bus data communication is considered for application in nuclear environments. The nuclear facilities, including nuclear power plants, high radioactivity waste disposals, reprocessing plants and thermonuclear fusion installations can benefit from the unique advantages of the field bus communication network for the smart field instruments and controls. A major problem which arises when dealing with one in these nuclear environments, in special circumstances such as the RCS (reactor coolant system) area, is the presence of high gamma-ray irradiation fields. Radioactive constraints for the DBA(design basis accident) qualification of the RTD transmitter installed in the inside of the RCS pump are typically on the order of 4kGy/h with total doses up to 10kGy. In order to use an industrial field bus communication network as an ad-hoc sensor data link in the vicinity of the RCS area of the nuclear power plant, the robust survivability of these system in such intense gamma-radiation fields therefore needs to be verified. We have conducted high dose-rate (up to 4kGy) gamma irradiation experiments on a profibus/DP communication module. In this paper we describe the evolution of its basic characteristics with high dose-rate gamma irradiation and shortly explain the observed phenomena.

Brachytherapy treatment with high dose rate

International Nuclear Information System (INIS)

Santana Rodriguez, Sergio Marcelino; Rodriguez Rodriguez, Lissi Lisbet; Ciscal Chiclana, Onelio Alberto

2009-01-01

Retrospectively analyze results and prognostic factors of cervical cancer patients treated with radio concomitant cisplatin-based chemotherapy, radiation therapy combined modality. Methods: From January 2003 to December 2007, 198 patients with invasive cervical cancer were treated at the Oncology Department of Hospital Robau Celestino Hernandez (brachytherapy performed at INOR). The most common age group was 31 to 40 years. The histology in squamous cell carcinoma accounted for 84.3% of cases. The treatment consisted of external pelvic irradiation and vaginal brachytherapy, high dose rate. Concomitant chemotherapy consisted of cisplatin 40 mg/m2 weekly with a maximum of 70 mg for 5 weeks. Results: 66.2% of patients completed 5 cycles of chemotherapy. The median overall survival was 39 months, overall survival, disease-free survival and survival free of locoregional recurrence at 5 years of 78%, 76% and 78.6% respectively .. We found that clinical stage, histological type (adenocarcinoma worst outcome) were statistically related to level of response. Conclusions: Treatment with external pelvic radiation, brachytherapy and concurrent weekly cisplatin in patients with stage IIIB cervical cancer is feasible in the Chilean public health system, well tolerated and results comparable to international literature. (Author)

Novel high dose rate lip brachytherapy technique to improve dose homogeneity and reduce toxicity by customized mold

International Nuclear Information System (INIS)

Feldman, Jon; Appelbaum, Limor; Sela, Mordechay; Voskoboinik, Ninel; Kadouri, Sarit; Weinberger, Jeffrey; Orion, Itzhak; Meirovitz, Amichay

2014-01-01

The purpose of this study is to describe a novel brachytherapy technique for lip Squamous Cell Carcinoma, utilizing a customized mold with embedded brachytherapy sleeves, which separates the lip from the mandible, and improves dose homogeneity. Seven patients with T2 lip cancer treated with a “sandwich” technique of High Dose Rate (HDR) brachytherapy to the lip, consisting of interstitial catheters and a customized mold with embedded catheters, were reviewed for dosimetry and outcome using 3D planning. Dosimetric comparison was made between the “sandwich” technique to “classic” – interstitial catheters only plan. We compared dose volume histograms for Clinical Tumor Volume (CTV), normal tissue “hot spots” and mandible dose. We are reporting according to the ICRU 58 and calculated the Conformal Index (COIN) to show the advantage of our technique. The seven patients (ages 36–81 years, male) had median follow-up of 47 months. Four patients received Brachytherapy and External Beam Radiation Therapy, 3 patients received brachytherapy alone. All achieved local control, with excellent esthetic and functional results. All patients are disease free. The Customized Mold Sandwich technique (CMS) reduced the high dose region receiving 150% (V150) by an average of 20% (range 1–47%), The low dose region (les then 90% of the prescribed dose) improved by 73% in average by using the CMS technique. The COIN value for the CMS was in average 0.92 as opposed to 0.88 for the interstitial catheter only. All differences (excluding the low dose region) were statistically significant. The CMS technique significantly reduces the high dose volume and increases treatment homogeneity. This may reduce the potential toxicity to the lip and adjacent mandible, and results in excellent tumor control, cosmetic and functionality

Intracavitary irradiation of prostatic carcinoma by a high dose-rate afterloading technique

Energy Technology Data Exchange (ETDEWEB)

Odelberg-Johnson, O.; Underskog, I.; Johansson, J.E.; Bernshaw, D.; Sorbe, B.; Persson, J.E. (Oerebro Medical Center Hospital (Sweden). Dept. of Oncology Oerebro Medical Center Hospital (Sweden). Dept. of Urology Oerebro Medical Center Hospital (Sweden). Dept. of Gynecologic Oncology Oerebro Medical Center Hospital (Sweden). Dept. of Radiation Physics)

1991-01-01

A high dose-rate ({sup 60}Co) afterloading technique was evaluated in a series of 73 patients with prostatic carcinoma stages I-IV. The intraurethral irradiation was combined with external pelvic radiotherapy. A minimum total dose of 78 Gy was delivered to the target volume. In a subgroup of patients extramustine (Estracyt) was given as adjuvant chemohormonal therapy during irradiation. The median follow-up for the whole group was 63 months. The crude 5-year survival rate was 60% and the corrected survival rate 90%. Survival was related to the tumor grade. Local pelvic recurrences were recorded in 17.8%. 'Viable cells' in posttherapy aspiration biopsy were not associated with tumor recurrences or survival. Four patients (5%) had grade 3 late radiation reactions with urethral structure or bladder fibrosis. Urinary tract infections and prior transurethral resections were not associated with a higher frequency of reactions. Concurrent estramustine therapy seemed to increase the frequency of both acute and chronic radiation reactions. Local control, recurrence, and survival were not affected by chemohormonal therapy. The use of tomography, magnetic resonance, and ultrasound as aids to computerized dosimetry may improve local dose distribution and reduce the irradiated volume. (orig.).

Radiobiological influence of megavoltage electron pulses of ultra-high pulse dose rate on normal tissue cells.

Science.gov (United States)

Laschinsky, Lydia; Karsch, Leonhard; Leßmann, Elisabeth; Oppelt, Melanie; Pawelke, Jörg; Richter, Christian; Schürer, Michael; Beyreuther, Elke

2016-08-01

Regarding the long-term goal to develop and establish laser-based particle accelerators for a future radiotherapeutic treatment of cancer, the radiobiological consequences of the characteristic short intense particle pulses with ultra-high peak dose rate, but low repetition rate of laser-driven beams have to be investigated. This work presents in vitro experiments performed at the radiation source ELBE (Electron Linac for beams with high Brilliance and low Emittance). This accelerator delivered 20-MeV electron pulses with ultra-high pulse dose rate of 10(10) Gy/min either at the low pulse frequency analogue to previous cell experiments with laser-driven electrons or at high frequency for minimizing the prolonged dose delivery and to perform comparison irradiation with a quasi-continuous electron beam analogue to a clinically used linear accelerator. The influence of the different electron beam pulse structures on the radiobiological response of the normal tissue cell line 184A1 and two primary fibroblasts was investigated regarding clonogenic survival and the number of DNA double-strand breaks that remain 24 h after irradiation. Thereby, no considerable differences in radiation response were revealed both for biological endpoints and for all probed cell cultures. These results provide evidence that the radiobiological effectiveness of the pulsed electron beams is not affected by the ultra-high pulse dose rates alone.

Radiobiological influence of megavoltage electron pulses of ultra-high pulse dose rate on normal tissue cells

International Nuclear Information System (INIS)

Laschinsky, Lydia; Karsch, Leonhard; Schuerer, Michael; Lessmann, Elisabeth; Beyreuther, Elke; Oppelt, Melanie; Pawelke, Joerg; Richter, Christian

2016-01-01

Regarding the long-term goal to develop and establish laser-based particle accelerators for a future radiotherapeutic treatment of cancer, the radiobiological consequences of the characteristic short intense particle pulses with ultra-high peak dose rate, but low repetition rate of laser-driven beams have to be investigated. This work presents in vitro experiments performed at the radiation source ELBE (Electron Linac for beams with high Brilliance and low Emittance). This accelerator delivered 20-MeV electron pulses with ultra-high pulse dose rate of 10"1"0 Gy/min either at the low pulse frequency analogue to previous cell experiments with laser-driven electrons or at high frequency for minimizing the prolonged dose delivery and to perform comparison irradiation with a quasi-continuous electron beam analogue to a clinically used linear accelerator. The influence of the different electron beam pulse structures on the radiobiological response of the normal tissue cell line 184A1 and two primary fibroblasts was investigated regarding clonogenic survival and the number of DNA double-strand breaks that remain 24 h after irradiation. Thereby, no considerable differences in radiation response were revealed both for biological endpoints and for all probed cell cultures. These results provide evidence that the radiobiological effectiveness of the pulsed electron beams is not affected by the ultra-high pulse dose rates alone. (orig.)

Radiation Exposure in Endovascular Infra-Renal Aortic Aneurysm Repair and Factors that Influence It

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Rui Machado

Full Text Available Abstract Objective: The endovascular repair of aortic abdominal aneurysms exposes the patients and surgical team to ionizing radiation with risk of direct tissue damage and induction of gene mutation. This study aims to describe our standard of radiation exposure in endovascular aortic aneurysm repair and the factors that influence it. Methods: Retrospective analysis of a prospective database of patients with abdominal infra-renal aortic aneurysms submitted to endovascular repair. This study evaluated the radiation doses (dose area product (DAP, fluoroscopy durations and their relationships to the patients, aneurysms, and stent-graft characteristics. Results: This study included 127 patients with a mean age of 73 years. The mean DAP was 4.8 mGy.m2, and the fluoroscopy time was 21.8 minutes. Aortic bilateral iliac aneurysms, higher body mass index, aneurysms with diameters larger than 60 mm, necks with diameters larger than 28 mm, common iliac arteries with diameters larger than 20 mm, and neck angulations superior to 50 degrees were associated with an increased radiation dose. The number of anatomic risk factors present was associated with increased radiation exposure and fluoroscopy time, regardless of the anatomical risk factors. Conclusion: The radiation exposure during endovascular aortic aneurysm repair is significant (mean DAP 4.8 mGy.m2 with potential hazards to the surgical team and the patients. The anatomical characteristics of the aneurysm, patient characteristics, and the procedure's technical difficulty were all related to increased radiation exposure during endovascular aortic aneurysm repair procedures. Approximately 40% of radiation exposure can be explained by body mass index, neck angulation, aneurysm diameter, neck diameter, and aneurysm type.

Quantitative analysis of biological responses to low dose-rate γ-radiation, including dose, irradiation time, and dose-rate

International Nuclear Information System (INIS)

Magae, J.; Furukawa, C.; Kawakami, Y.; Hoshi, Y.; Ogata, H.

2003-01-01

Full text: Because biological responses to radiation are complex processes dependent on irradiation time as well as total dose, it is necessary to include dose, dose-rate and irradiation time simultaneously to predict the risk of low dose-rate irradiation. In this study, we analyzed quantitative relationship among dose, irradiation time and dose-rate, using chromosomal breakage and proliferation inhibition of human cells. For evaluation of chromosome breakage we assessed micronuclei induced by radiation. U2OS cells, a human osteosarcoma cell line, were exposed to gamma-ray in irradiation room bearing 50,000 Ci 60 Co. After the irradiation, they were cultured for 24 h in the presence of cytochalasin B to block cytokinesis, cytoplasm and nucleus were stained with DAPI and propidium iodide, and the number of binuclear cells bearing micronuclei was determined by fluorescent microscopy. For proliferation inhibition, cells were cultured for 48 h after the irradiation and [3H] thymidine was pulsed for 4 h before harvesting. Dose-rate in the irradiation room was measured with photoluminescence dosimeter. While irradiation time less than 24 h did not affect dose-response curves for both biological responses, they were remarkably attenuated as exposure time increased to more than 7 days. These biological responses were dependent on dose-rate rather than dose when cells were irradiated for 30 days. Moreover, percentage of micronucleus-forming cells cultured continuously for more than 60 days at the constant dose-rate, was gradually decreased in spite of the total dose accumulation. These results suggest that biological responses at low dose-rate, are remarkably affected by exposure time, that they are dependent on dose-rate rather than total dose in the case of long-term irradiation, and that cells are getting resistant to radiation after the continuous irradiation for 2 months. It is necessary to include effect of irradiation time and dose-rate sufficiently to evaluate risk

The impact of the oxygen scavenger on the dose-rate dependence and dose sensitivity of MAGIC type polymer gels

Science.gov (United States)

Khan, Muzafar; Heilemann, Gerd; Kuess, Peter; Georg, Dietmar; Berg, Andreas

2018-03-01

Recent developments in radiation therapy aimed at more precise dose delivery along with higher dose gradients (dose painting) and more efficient dose delivery with higher dose rates e.g. flattening filter free (FFF) irradiation. Magnetic-resonance-imaging based polymer gel dosimetry offers 3D information for precise dose delivery techniques. Many of the proposed polymer gels have been reported to exhibit a dose response, measured as relaxation rate ΔR2(D), which is dose rate dependent. A lack of or a reduced dose-rate sensitivity is very important for dosimetric accuracy, especially with regard to the increasing clinical use of FFF irradiation protocols with LINACs at high dose rates. Some commonly used polymer gels are based on Methacrylic-Acid-Gel-Initiated-by-Copper (MAGIC). Here, we report on the dose sensitivity (ΔR2/ΔD) of MAGIC-type gels with different oxygen scavenger concentration for their specific dependence on the applied dose rate in order to improve the dosimetric performance, especially for high dose rates. A preclinical x-ray machine (‘Yxlon’, E  =  200 kV) was used for irradiation to cover a range of dose rates from low \\dot{D} min  =  0.6 Gy min-1 to high \\dot{D} max  =  18 Gy min-1. The dose response was evaluated using R2-imaging of the gel on a human high-field (7T) MR-scanner. The results indicate that all of the investigated dose rates had an impact on the dose response in polymer gel dosimeters, being strongest in the high dose region and less effective for low dose levels. The absolute dose rate dependence \\frac{(Δ R2/Δ D)}{Δ \\dot{D}} of the dose response in MAGIC-type gel is significantly reduced using higher concentrations of oxygen scavenger at the expense of reduced dose sensitivity. For quantitative dose evaluations the relative dose rate dependence of a polymer gel, normalized to its sensitivity is important. Based on this normalized sensitivity the dose rate sensitivity was reduced distinctly

Desensitization Using Bortezomib and High-dose Immunoglobulin Increases Rate of Deceased Donor Kidney Transplantation.

Science.gov (United States)

Jeong, Jong Cheol; Jambaldorj, Enkthuya; Kwon, Hyuk Yong; Kim, Myung-Gyu; Im, Hye Jin; Jeon, Hee Jung; In, Ji Won; Han, Miyeun; Koo, Tai Yeon; Chung, Junho; Song, Eun Young; Ahn, Curie; Yang, Jaeseok

2016-02-01

Combination therapy of intravenous immunoglobulin (IVIG) and rituximab showed a good transplant rate in highly sensitized wait-listed patients for deceased donor kidney transplantation (DDKT), but carried the risk of antibody-mediated rejection. The authors investigated the impact of a new combination therapy of bortezomib, IVIG, and rituximab on transplantation rate.This study was a prospective, open-labeled clinical trial. The desensitization regimen consisted of 2 doses of IVIG (2  g/kg), a single dose of rituximab (375  mg/m), and 4 doses of bortezomib (1.3  mg/m). The transplant rate was analyzed. Anti-Human leukocyte antigen (HLA) DRB antibodies were determined by a Luminex solid-phase bead assay at baseline and after 2, 3, and 6 months in the desensitized patients.There were 19 highly sensitized patients who received desensitization and 17 patients in the control group. Baseline values of class I and II panel reactive antibody (%, peak mean fluorescence intensity) were 83  ±  16.0 (14952  ±  5820) and 63  ±  36.0 (10321  ±  7421), respectively. Deceased donor kidney transplantation was successfully performed in 8 patients (42.1%) in the desensitization group versus 4 (23.5%) in the control group. Multivariate time-varying covariate Cox regression analysis showed that desensitization increased the probability of DDKT (hazard ratio, 46.895; 95% confidence interval, 3.468-634.132; P = 0.004). Desensitization decreased mean fluorescence intensity values of class I panel reactive antibody by 15.5% (20.8%) at 2 months. In addition, a liberal mismatch strategy in post hoc analysis increased the benefit of desensitization in donor-specific antibody reduction. Desensitization was well tolerated, and acute rejection occurred only in the control group.In conclusion, a desensitization protocol using bortezomib, high-dose IVIG, and rituximab increased the DDKT rate in highly sensitized, wait-listed patients.

A multidetector tomography protocol for follow-up of endovascular aortic aneurysm repair

Directory of Open Access Journals (Sweden)

Roberto Moraes Bastos

2011-01-01

Full Text Available OBJECTIVE: The purpose of this study was to improve the use of 64-channel multidetector computed tomography using lower doses of ionizing radiation during follow-up procedures in a series of patients with endovascular aortic aneurysm repair. METHODS: Thirty patients receiving 5 to 29 months of follow-up after endovascular aortic aneurysm repair were analyzed using a 64-channel multidetector computed tomography device by an exam that included pre-and postcontrast with both arterial and venous phases. Leak presence and type were classified based on the exam phase. RESULTS: Endoleaks were identified in 8/30 of cases; the endoleaks in 3/8 of these cases were not visible in the arterial phases of the exams. CONCLUSION: The authors conclude that multidetector computed tomography with pre-contrast and venous phases should be a part of the ongoing follow-up of patients undergoing endovascular aortic aneurysm repair. The arterial phase can be excluded when the aneurism is stable or regresses. These findings permit a lower radiation dose without jeopardizing the correct diagnosis of an endoleak.

Clastogenic effects in human lymphocytes exposed to low and high dose rate X-ray irradiation and vitamin C

International Nuclear Information System (INIS)

Konopacka, M; Rogolinski, J.

2011-01-01

In the present work we investigated the ability of vitamin C to modulate clastogenic effects induced in cultured human lymphocytes by X-irradiation delivered at either high (1 Gy/min) or low dose rate (0.24 Gy/min). Biological effects of the irradiation were estimated by cytokinesis-block micronucleus assay including the analysis of the frequency of micronuclei (MN) and apoptotic cells as well as calculation of nuclear division index (NDI). The numbers of micronucleated binucleate lymphocytes (MN-CBL) were 24.85 ± 2.67% and 32.56 ± 3.17% in cultures exposed to X-rays (2 Gy) delivered at low and high dose rates, respectively. Addition of vitamin C (1-20 μg/ml) to the medium of cultures irradiated with the low dose rate reduced the frequency of micronucleated lymphocytes with multiple MN in a concentration-dependent manner. Lymphocytes exposed to the high dose rate radiation showed a U-shape response: low concentration of vitamin C significantly reduced the number of MN, whereas high concentration influenced the radiation-induced total number of micronucleated cells insignificantly, although it increased the number of cells with multiple MN. Addition of vitamin C significantly reduced the fraction of apoptotic cells, irrespective of the X-ray dose rate. These results indicate that radiation dose rate is an important exposure factor, not only in terms of biological cell response to irradiation, but also with respect to the modulating effects of antioxidants. (authors)

A graphical review of radiogenic animal cancer data using the 'dose and dose-rate map'

International Nuclear Information System (INIS)

Yoshida, Kazuo; Hoshi, Yuko; Sakai, Kazuo

2008-01-01

We have been investigating the effects of low dose or low dose rate irradiation on mice, using our low dose-rate irradiation facilities. In these studies, we found that the effects were highly dependent on both total dose and dose rate. To show this visually, we proposed the 'dose/dose rate map', and plotted the results of our laboratory and our co-workers. The map demonstrated that dose/dose rate plane could be divided into three areas; 1) An area where harmful effects are observed, 2) An area where no harmful effects are observed, and 3) Another area, between previous two areas, where certain protective functions are enhanced. As this map would be a powerful tool to find some trend among the vast numbers of data relating the biological effects of ionizing radiation, we have developed a computer program which plots the collected data on the dose/dose rate map sorting by experimental conditions. In this study, we graphically reviewed and analyzed the data relating to the lifespan studies of animals with a view to determining the relationships between doses and dose rates of ionizing radiation and cancer incidence. The data contains about 800 sets of experiments, which concerns 187,000 animals exposed to gamma ray or X-ray and their 112,000 controls, and total of about 30,000 cancers in exposed animals and 14,000 cancers in controls. About 800 points of data were plotted on the dose/dose rate map. The plot showed that 1) The divided three areas in the dose/dose rate map were generally confirmed by these 800 points of data, and 2) In some particular conditions, e.g. sarcoma by X-rays, the biologically effective area is extended to relatively high dose/dose rate area. (author)

Radiobiological responses for two cell lines following continuous low dose-rate (CLDR) and pulsed dose rate (PDR) brachytherapy

International Nuclear Information System (INIS)

Hanisch, Per Henrik; Furre, Torbjoern; Olsen, Dag Rune; Pettersen, Erik O.

2007-01-01

The iso-effective irradiation of continuous low-dose-rate (CLDR) irradiation was compared with that of various schedules of pulsed dose rate (PDR) irradiation for cells of two established human lines, T-47D and NHIK 3025. Complete single-dose response curves were obtained for determination of parameters α and β by fitting of the linear quadratic formula. Sublethal damage repair constants μ and T 1/2 were determined by split-dose recovery experiments. On basis of the acquired parameters of each cell type the relative effectiveness of the two regimens of irradiation (CLDR and PDR) was calculated by use of Fowler's radiobiological model for iso-effect irradiation for repeated fractions of dose delivered at medium dose rates. For both cell types the predicted and observed relative effectiveness was compared at low and high iso-effect levels. The results indicate that the effect of PDR irradiation predicted by Fowler's model is equal to that of CLDR irradiation for both small and large doses with T-47D cells. With NHIK 3025 cells PDR irradiation induces a larger effect than predicted by the model for small doses, while it induces the predicted effect for high doses. The underlying cause of this difference is unclear, but cell-cycle parameters, like G2-accumulation is tested and found to be the same for the two cell lines

Calibration in a manikin of a high dose rate equipment by remote charge

International Nuclear Information System (INIS)

Alfonso La Guardia, Rodolfo; Toledo Jimenez, Pablo; Pich Leon, Victor

1996-01-01

The aim of this study was to know the immediate results obtained with laparoscopic cholecystectomy in The use of High Dose Rate brachytherapy in Cuba has been limited to AGAT-V Soviet installations. In order to calibrate one of these installations for its clinical use, it was developed a procedure based on the direct measurement of the dose absorbed in referral point B of a paraffin manikin. Results obtained as a result of calibration are shown. According to these results, it was carried out an evaluation of the effective doses administered on prescription point A by using the linear quadratic model

Clinical result of high-dose rate intraluminal brachytherapy for esophageal carcinoma with a remote afterloading system

International Nuclear Information System (INIS)

Fukuda, Haruyuki; Nakajima, Toshifumi; Tada, Takuhito; Tanaka, Masahiro; Tsumura, Masashi; Onoyama, Yasuto

1992-01-01

During the period from 1977 through 1987, 105 patients with esophageal carcinoma were radically treated by radiotherapy. Forty-six patients receiving therapy before August 1982 were all treated by external beam therapy alone (Group 1). Since September 1982, 26 patients were treated by external beam therapy alone (Group 2) and 33 patients were treated by high-dose-rate intraluminal brachytherapy with a remote afterloading system combined with external beam therapy (Group 3). Dose of external beam therapy for Group 1, Group 2 and Group 3 patients were 66.7 Gy, 68.7 Gy and 55.9 Gy on the average. The intraluminal brachytherapy was performed with a total dose of 12 Gy consisting of 3 Gy twice a week. Ten of 72 patients (14%) treated by external beam therapy alone achieved complete response, whereas 14 of 33 patients (42%) treated by high-dose-rate intraluminal brachytherapy combined with external beam therapy had complete response. One-, and 3-year survival rates were 36% and 10% in the Group 1, 32% and 12% in the Group 2 and 56% and 36% in the Group 3. For Group 3, good survival rate was obtained in tumorous type and serrated type. Patients with tumor of less than 5 cm in Group 3 had good survival. The data suggest that the high-dose-rate intraluminal bracytherapy prescribed as a boost therapy following external beam therapy is an effective therapy modality for esophageal carcinoma which is of non-circumferential tumor or less than 5 cm. (author)

Implementation of microsource high dose rate (mHDR) brachytherapy in developing countries

International Nuclear Information System (INIS)

2001-11-01

Brachytherapy using remote afterloading of a single high dose rate 192 Ir microsource was developed in the 1970s. After its introduction to clinics, this system has spread rapidly among developed Member States and has become a highly desirable modality in cancer treatment. This technique is now gradually being introduced to the developing Member States. The 192 Ir sources are produced with a high specific activity. This results in a high dose rate (HDR) to the tumour and shorter treatment times. The high specific activity simultaneously results in a much smaller source (so-called micro source, around I mm in diameter) which may be easily inserted into tissue through a thin delivery tube, the so-called interstitial treatment, as well as easily inserted into body cavities, the so-called intracavitary or endoluminal treatment. Another advantage is the ability to change dwell time (the time a source remains in one position) of the stepping source which allows dose distribution to match the target volume more closely. The purpose of this TECDOC is to advise radiation oncologists, medical physicists and hospital administrators in hospitals which are planning to introduce 192 Ir microsource HDR (mHDR) remote afterloading systems. The document supplements IAEA-TECDOC-1040, Design and Implementation of a Radiotherapy Programme: Clinical, Medical Physics, Radiation Protection and Safety Aspects, and will facilitate implementation of this new brachytherapy technology, especially in developing countries. The operation of the system, 'how to use the system', is not within the scope of this document. This TECDOC is based on the recommendations of an Advisory Group meeting held in Vienna in April 1999

Brachytherapy for cervix cancer: low-dose rate or high-dose rate brachytherapy – a meta-analysis of clinical trials

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Stefano Eduardo J

2009-04-01

Full Text Available Abstract Background The literature supporting high-dose rate brachytherapy (HDR in the treatment of cervical carcinoma derives primarily from retrospective series. However, controversy still persists regarding the efficacy and safety of HDR brachytherapy compared to low-dose rate (LDR brachytherapy, in particular, due to inadequate tumor coverage for stage III patients. Whether LDR or HDR brachytherapy produces better results for these patients in terms of survival rate, local control rate and the treatment complications remain controversial. Methods A meta-analysis of RCT was performed comparing LDR to HDR brachytherapy for cervix cancer treated for radiotherapy alone. The MEDLINE, EMBASE, CANCERLIT and Cochrane Library databases, as well as abstracts published in the annual proceedings were systematically searched. We assessed methodological quality for each outcome by grading the quality of evidence using the Grading of Recommendations Assessment, Development and Evaluation (GRADE methodology. We used "recommend" for strong recommendations, and "suggest" for weak recommendations. Results Pooled results from five randomized trials (2,065 patients of HDR brachytherapy in cervix cancer showed no significant increase of mortality (p = 0.52, local recurrence (p = 0.68, or late complications (rectal; p = 0.7, bladder; p = 0.95 or small intestine; p = 0.06 rates as compared to LDR brachytherapy. In the subgroup analysis no difference was observed for overall mortality and local recurrence in patients with clinical stages I, II and III. The quality of evidence was low for mortality and local recurrence in patients with clinical stage I, and moderate for other clinical stages. Conclusion Our meta-analysis shows that there are no differences between HDR and LDR for overall survival, local recurrence and late complications for clinical stages I, II and III. By means of the GRADE system, we recommend the use of HDR for all clinical stages of cervix

Brachytherapy for cervix cancer: low-dose rate or high-dose rate brachytherapy – a meta-analysis of clinical trials

Science.gov (United States)

Viani, Gustavo A; Manta, Gustavo B; Stefano, Eduardo J; de Fendi, Ligia I

2009-01-01

Background The literature supporting high-dose rate brachytherapy (HDR) in the treatment of cervical carcinoma derives primarily from retrospective series. However, controversy still persists regarding the efficacy and safety of HDR brachytherapy compared to low-dose rate (LDR) brachytherapy, in particular, due to inadequate tumor coverage for stage III patients. Whether LDR or HDR brachytherapy produces better results for these patients in terms of survival rate, local control rate and the treatment complications remain controversial. Methods A meta-analysis of RCT was performed comparing LDR to HDR brachytherapy for cervix cancer treated for radiotherapy alone. The MEDLINE, EMBASE, CANCERLIT and Cochrane Library databases, as well as abstracts published in the annual proceedings were systematically searched. We assessed methodological quality for each outcome by grading the quality of evidence using the Grading of Recommendations Assessment, Development and Evaluation (GRADE) methodology. We used "recommend" for strong recommendations, and "suggest" for weak recommendations. Results Pooled results from five randomized trials (2,065 patients) of HDR brachytherapy in cervix cancer showed no significant increase of mortality (p = 0.52), local recurrence (p = 0.68), or late complications (rectal; p = 0.7, bladder; p = 0.95 or small intestine; p = 0.06) rates as compared to LDR brachytherapy. In the subgroup analysis no difference was observed for overall mortality and local recurrence in patients with clinical stages I, II and III. The quality of evidence was low for mortality and local recurrence in patients with clinical stage I, and moderate for other clinical stages. Conclusion Our meta-analysis shows that there are no differences between HDR and LDR for overall survival, local recurrence and late complications for clinical stages I, II and III. By means of the GRADE system, we recommend the use of HDR for all clinical stages of cervix cancer. PMID:19344527

Review of low dose-rate epidemiological studies and biological mechanisms of dose-rate effects on radiation induced carcinogenesis

International Nuclear Information System (INIS)

Iwasaki, Toshiyasu; Otsuka, Kensuke; Yoshida, Kazuo

2015-01-01

Radiation protection system adopts the linear non-threshold model with using dose and dose-rate effectiveness factor (DDREF). The dose-rate range where DDREF is applied is below 100 mGy per hour, and it is regarded that there are no dose-rate effects at very low dose rate, less than of the order of 10 mGy per year, even from the biological risk evaluation model based on cellular and molecular level mechanisms for maintenance of genetic integrity. Among low dose-rate epidemiological studies, studies of residents in high natural background areas showed no increase of cancer risks at less than about 10 mGy per year. On the other hand, some studies include a study of the Techa River cohort suggested the increase of cancer risks to the similar degree of Atomic bomb survivor data. The difference of those results was supposed due to the difference of dose rate. In 2014, International Commission on Radiological Protection opened a draft report on stem cell biology for public consultations. The report proposed a hypothesis based on the new idea of stem cell competition as a tissue level quality control mechanism, and suggested that it could explain the dose-rate effects around a few milligray per year. To verify this hypothesis, it would be needed to clarify the existence and the lowest dose of radiation-induced stem cell competition, and to elucidate the rate of stem cell turnover and radiation effects on it. As for the turnover, replenishment of damaged stem cells would be the important biological process. It would be meaningful to collect the information to show the difference of dose rates where the competition and the replenishment would be the predominant processes. (author)

Postoperative vaginal irradiation with high dose rate afterloading technique in endometrial carcinoma stage I

International Nuclear Information System (INIS)

Sorbe, B.G.; Smeds, A.C.

1990-01-01

A high dose rate ( 60 Co) afterloading technique was used for postoperative prophylactic vaginal irradiation in a series of 404 women with endometrial carcinoma Stage I. The total recurrence rate was 3.7% with 0.7% vaginal deposits. The crude 5-year survival rate for the complete series was 91.8% compared to 13.3% for those with recurrences. Depth of myometrial infiltration (greater than 1/3 of the uterine wall) and nuclear grade were the most important prognostic factors. Clinically significant late radiation reactions (bladder and/or rectum) were recorded in 6.9%. Dose per fraction and the size of the target volume were highly significantly related to the occurrence of both early and late radiation reactions. Vaginal shortening is closely related to the dose per fraction, length of the reference isodose, and the applicator diameter. The shape of the vaginal applicator versus the isodoses and the importance of the source train geometry and relative activity for dose gradient inhomogeneities within the target volume are discussed. Cumulative radiation effect (CRE) and linear-quadratic (LQ) calculations have been performed and related to tissue reactions within the target volume and in the risk organs. An alpha-beta quotient of 8.8 for vaginal shrinkage effect and 2.0 for late rectal complications are suggested on the basis of calculations using a maximum likelihood method for quantal radiation data

Cancer radiotherapy based on femtosecond IR laser-beam filamentation yielding ultra-high dose rates and zero entrance dose.

Science.gov (United States)

Meesat, Ridthee; Belmouaddine, Hakim; Allard, Jean-François; Tanguay-Renaud, Catherine; Lemay, Rosalie; Brastaviceanu, Tiberius; Tremblay, Luc; Paquette, Benoit; Wagner, J Richard; Jay-Gerin, Jean-Paul; Lepage, Martin; Huels, Michael A; Houde, Daniel

2012-09-18

Since the invention of cancer radiotherapy, its primary goal has been to maximize lethal radiation doses to the tumor volume while keeping the dose to surrounding healthy tissues at zero. Sadly, conventional radiation sources (γ or X rays, electrons) used for decades, including multiple or modulated beams, inevitably deposit the majority of their dose in front or behind the tumor, thus damaging healthy tissue and causing secondary cancers years after treatment. Even the most recent pioneering advances in costly proton or carbon ion therapies can not completely avoid dose buildup in front of the tumor volume. Here we show that this ultimate goal of radiotherapy is yet within our reach: Using intense ultra-short infrared laser pulses we can now deposit a very large energy dose at unprecedented microscopic dose rates (up to 10(11) Gy/s) deep inside an adjustable, well-controlled macroscopic volume, without any dose deposit in front or behind the target volume. Our infrared laser pulses produce high density avalanches of low energy electrons via laser filamentation, a phenomenon that results in a spatial energy density and temporal dose rate that both exceed by orders of magnitude any values previously reported even for the most intense clinical radiotherapy systems. Moreover, we show that (i) the type of final damage and its mechanisms in aqueous media, at the molecular and biomolecular level, is comparable to that of conventional ionizing radiation, and (ii) at the tumor tissue level in an animal cancer model, the laser irradiation method shows clear therapeutic benefits.

Endovascular repair of blunt popliteal arterial injuries

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Zhong, Shan; Zhang, Xiquan; Chen, Zhong; Zhu, Wei; Pan, Xiaolin [Dept. of nterventional Vascular, The 148th Hospital of Chinese People' s Liberation Army, Zibo (China); Dong, Peng; Sun, Yequan [Dept. of Medical Imaging, Weifang Medical University, Weifang (China); Qi, Deming [Dept. of Medical Imaging, Qilu Medical University, Zibo (China)

2016-09-15

To evaluate the feasibility and effectiveness of endovascular repair for blunt popliteal arterial injuries. A retrospective analysis of seven patients with clinical suspicion of popliteal arterial injuries that were confirmed by arteriography was performed from September 2009 to July 2014. Clinical data included demographics, mechanism of injury, type of injury, location of injury, concomitant injuries, time of endovascular procedures, time interval from trauma to blood flow restoration, instrument utilized, and follow-up. All patients were male (mean age of 35.9 ± 10.3 years). The type of lesion involved intimal injury (n = 1), partial transection (n = 2), complete transection (n = 2), arteriovenous fistula (n = 1), and pseudoaneurysm (n = 1). All patients underwent endovascular repair of blunt popliteal arterial injuries. Technical success rate was 100%. Intimal injury was treated with a bare-metal stent. Pseudoaneurysm and popliteal artery transections were treated with bare-metal stents. Arteriovenous fistula was treated with bare-metal stent and coils. No perioperative death and procedure-related complication occurred. The average follow-up was 20.9 ± 2.3 months (range 18–24 months). One patient underwent intra-arterial thrombolysis due to stent thrombosis at 18 months after the procedure. All limbs were salvaged. Stent migration, deformation, or fracture was not found during the follow-up. Endovascular repair seems to be a viable approach for patients with blunt popliteal arterial injuries, especially on an emergency basis. Endovascular repair may be effective in the short-term. Further studies are required to evaluate the long-term efficacy of endovascular repair.

Dosimetric Effects of Air Pockets Around High-Dose Rate Brachytherapy Vaginal Cylinders

International Nuclear Information System (INIS)

Richardson, Susan; Palaniswaamy, Geethpriya; Grigsby, Perry W.

2010-01-01

Purpose: Most physicians use a single-channel vaginal cylinder for postoperative endometrial cancer brachytherapy. Recent published data have identified air pockets between the vaginal cylinders and the vaginal mucosa. The purpose of this research was to evaluate the incidence, size, and dosimetric effects of these air pockets. Methods and Materials: 25 patients receiving postoperative vaginal cuff brachytherapy with a high-dose rate vaginal cylinders were enrolled in this prospective data collection study. Patients were treated with 6 fractions of 200 to 400 cGy per fraction prescribed at 5 mm depth. Computed tomography simulation for brachytherapy treatment planning was performed for each fraction. The quantity, volume, and dosimetric impact of the air pockets surrounding the cylinder were quantified. Results: In 25 patients, a total of 90 air pockets were present in 150 procedures (60%). Five patients had no air pockets present during any of their treatments. The average number of air pockets per patient was 3.6, with the average total air pocket volume being 0.34 cm 3 (range, 0.01-1.32 cm 3 ). The average dose reduction to the vaginal mucosa at the air pocket was 27% (range, 9-58%). Ten patients had no air pockets on their first fraction but air pockets occurred in subsequent fractions. Conclusion: Air pockets between high-dose rate vaginal cylinder applicators and the vaginal mucosa are present in the majority of fractions of therapy, and their presence varies from patient to patient and fraction to fraction. The existence of air pockets results in reduced radiation dose to the vaginal mucosa.

Endovascular Mechanical Thrombectomy in Basilar Artery Occlusion: Initial Experience

Science.gov (United States)

Park, Bum-Soo; Kwon, Hyon-Jo; Choi, Seung-Won; Kim, Seon-Hwan; Koh, Hyeon-Song; Youm, Jin-Young; Song, Shi-Hun

2013-01-01

Objective This study was conducted to assess the efficacy and safety of endovascular mechanical thrombectomy (EMT) for patients diagnosed with basilar artery (BA) occlusion. Materials and Methods We retrospectively analyzed clinical and imaging data of 16 patients diagnosed with BA occlusion who were treated with endovascular intervention from July 2012 to February 2013. Direct suction using the Penumbra system and thrombus retrieval by the Solitaire stent were the main endovascular techniques used to restore BA flow. The outcomes were evaluated based on rate of angiographic recanalization, rate of improvement of National Institutes of Health Stroke Scale (NIHSS) score, rate of modified Rankin Scale (mRS) at discharge and after 3 months, and rate of cerebral hemorrhagic complications. Successful recanalization was defined as achieving Thrombolysis In Cerebral Infarction (TICI) of II or III. Results Sixteen patients received thrombectomy. The mean age was 67.8 ± 11 years and the mean NIHSS score was 12.3 ± 8.2. Eight patients treated within 6 hours of symptom onset were grouped as A and the other 8 patients treated beyond 6 hours (range, 6-120) were grouped as B. Successful recanalization was met in six patients (75%) for group A and 7 (87.5%) for group B. Favorable outcome occurred in 4 patients (50%) for group A and 5 (62.5%) for group B. Conclusion Our study supports the effectiveness and safety of endovascular mechanical thrombectomy in treating BA occlusion even 6 hours after symptom onset. PMID:24167791

Radiation safety program in high dose rate brachytherapy facility at INHS Asvini

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Kirti Tyagi

2014-01-01

Full Text Available Brachytherapy concerns primarily the use of radioactive sealed sources which are inserted into catheters or applicators and placed directly into tissue either inside or very close to the target volume. The use of radiation in treatment of patients involves both benefits and risks. It has been reported that early radiation workers had developed radiation induced cancers. These incidents lead to continuous work for the improvement of radiation safety of patients and personnel The use of remote afterloading equipment has been developed to improve radiation safety in the delivery of treatment in brachytherapy. The widespread adoption of high dose rate brachytherapy needs appropriate quality assurance measures to minimize the risks to both patients and medical staff. The radiation safety program covers five major aspects: quality control, quality assurance, radiation monitoring, preventive maintenance, administrative measures and quality audit. This paper will discuss the radiation safety program developedfor a high dose rate brachytherapy facility at our centre which may serve as a guideline for other centres intending to install a similar facility.

High-dose-rate brachytherapy in uterine cervical carcinoma

International Nuclear Information System (INIS)

Patel, Firuza D.; Rai, Bhavana; Mallick, Indranil; Sharma, Suresh C.

2005-01-01

Purpose: High-dose-rate (HDR) brachytherapy is in wide use for curative treatment of cervical cancer. The American Brachytherapy Society has recommended that the individual fraction size be <7.5 Gy and the range of fractions should be four to eight; however, many fractionation schedules, varying from institution to institution, are in use. We use 9 Gy/fraction of HDR in two to five fractions in patients with carcinoma of the uterine cervix. We found that our results and toxicity were comparable to those reported in the literature and hereby present our experience with this fractionation schedule. Methods and Materials: A total of 121 patients with Stage I-III carcinoma of the uterine cervix were treated with HDR brachytherapy between 1996 and 2000. The total number of patients analyzed was 113. The median patient age was 53 years, and the histopathologic type was squamous cell carcinoma in 93% of patients. The patients were subdivided into Groups 1 and 2. In Group 1, 18 patients with Stage Ib-IIb disease, tumor size <4 cm, and preserved cervical anatomy underwent simultaneous external beam radiotherapy to the pelvis to a dose of 40 Gy in 20 fractions within 4 weeks with central shielding and HDR brachytherapy of 9 Gy/fraction, given weekly, and interdigitated with external beam radiotherapy. The 95 patients in Group 2, who had Stage IIb-IIIb disease underwent external beam radiotherapy to the pelvis to a dose of 46 Gy in 23 fractions within 4.5 weeks followed by two sessions of HDR intracavitary brachytherapy of 9 Gy each given 1 week apart. The follow-up range was 3-7 years (median, 36.4 months). Late toxicity was graded according to the Radiation Therapy Oncology Group criteria. Results: The 5-year actuarial local control and disease-free survival rate was 74.5% and 62.0%, respectively. The actuarial local control rate at 5 years was 100% for Stage I, 80% for Stage II, and 67.2% for Stage III patients. The 5-year actuarial disease-free survival rate was 88.8% for

A Performance Evaluation of a Notebook PC under a High Dose-Rate Gamma Ray Irradiation Test

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Jai Wan Cho

2014-01-01

Full Text Available We describe the performance of a notebook PC under a high dose-rate gamma ray irradiation test. A notebook PC, which is small and light weight, is generally used as the control unit of a robot system and loaded onto the robot body. Using TEPCO’s CAMS (containment atmospheric monitoring system data, the gamma ray dose rate before and after a hydrogen explosion in reactor units 1–3 of the Fukushima nuclear power plant was more than 150 Gy/h. To use a notebook PC as the control unit of a robot system entering a reactor building to mitigate the severe accident situation of a nuclear power plant, the performance of the notebook PC under such intense gamma-irradiation fields should be evaluated. Under a similar dose-rate (150 Gy/h gamma ray environment, the performances of different notebook PCs were evaluated. In addition, a simple method for a performance evaluation of a notebook PC under a high dose-rate gamma ray irradiation test is proposed. Three notebook PCs were tested to verify the method proposed in this paper.

High dose rate intracavitary afterloading irradiation in malignant inoperable obturation of bile ducts

Energy Technology Data Exchange (ETDEWEB)

Itami, J.; Saegusa, K.; Mamiya, T.; Miyoshi, T.; Arimizu, N.; Tsuchiya, Y.; Ohto, M.

1986-02-01

After decompression of the bile duct with PTCD, seven patients with carcinomas of the bile ducts were submitted to an intracavitary Ir-afterloading irradiation performed according to the high-dose-rate method with a Buchler device. Most of the patients were irradiated with 30 Gy in two fractions. Five patients were also exposed to percutaneous radiation with 40 to 50 Gy. Local control was achieved in six patients. One patient developed a locoregional recurrence which was possibly due to a so-called 'geographic miss'. In one patient a benign fibrotic stenosis of the bile duct was found at the site of most intensive irradiation. Intracavitary irradiation is very important in the treatment of malignant of bile ducts. However, there is an urgent need of research with regard to the combined method with percutaneous irradiation and to the optimum fractionation of intracavitary high dose rate irradiation.

Helicoverpa armigera (Lepidoptera: Noctuidae) larvae that survive sublethal doses of nucleopolyhedrovirus exhibit high metabolic rates.

Science.gov (United States)

Bouwer, Gustav; Nardini, Luisa; Duncan, Frances D

2009-04-01

To determine the effect of sublethal doses of Helicoverpa armigera single nucleocapsid nucleopolyhedrovirus (HearSNPV) on the metabolic rate of H. armigera, the respiration rates of third instar H. armigera larvae inoculated with sublethal doses of HearSNPV were evaluated. Respiration rates, measured as the rate of CO(2) production (VCO(2)), were recorded daily using closed-system respirometry. By 4 days post-inoculation (dpi), the metabolic rates of LD(25) or LD(75) survivors were significantly higher than that of uninoculated controls. When dose data were pooled, the VCO(2) values of larvae that survived inoculation (0.0288mlh(-1)), the uninoculated controls (0.0250mlh(-1)), and the larvae that did not survive inoculation (0.0199mlh(-1)) differed significantly from one another. At 4dpi, the VCO(2) of the uninoculated controls were significantly lower than the VCO(2) of inoculation survivors, but significantly higher than the VCO(2) of inoculation non-survivors. Inoculation survivors may have had high metabolic rates due to a combination of viral replication, organ damage, and an energy-intensive induced cellular immune response. The high 4dpi metabolic rate of inoculation survivors may reflect an effective immune response and may be seen as the metabolic signature of larvae that are in the process of surviving inoculation with HearSNPV.

Dose rate effect in food irradiation

International Nuclear Information System (INIS)

Singh, H.

1991-08-01

It has been suggested that the minor losses of nutrients associated with radiation processing may be further reduced by irradiating foods at the high dose rates generally associated with electron beams from accelerators, rather than at the low dose rates typical of gamma irradiation (e.g. 60 Co). This review briefly examines available comparative data on gamma and electron irradiation of foods to evaluate these suggestions. (137 refs., 27 tabs., 11 figs.)

Dosimetric advancement of high-dose-rate after-loading 192Ir source

International Nuclear Information System (INIS)

Zhang Shuxu; Li Wenhua; Xu Hairong

2004-01-01

High-dose-rate (HDR) 192 Ir source is a nuclide commonly used in the brachytherapy system. The basic dosimetry data of the near source area is usually measured by pin ion chambers or TLD techniques, but these methods have a lower spatial resolution than Electron spin resonance (ESR) dosimetry which has a spatial resolution of 156 μm, and the Monte Carlo photon transport simulations are taken as the golden standard of those measures. The precision in two-dimensional dose distribution measured by GafChromic film is reported to be 1.0%. In vivo dosimetry using TLD during HDR intracavitary after-loading brachytherapy is a good predictor of late rectal complications. The accuracy of magnetic resonance imaging (MRI) Fricke-gel dosimetry for three-dimensional dose distribution is about 2.5% with a spatial resolution of 1.56 mm. The optical computed tomography polymer gel dosimetry has a unique advance than MRI gel dosimetry

Dose and dose rate effects of whole-body gamma-irradiation: I. Lymphocytes and lymphoid organs

Science.gov (United States)

Pecaut, M. J.; Nelson, G. A.; Gridley, D. S.

2001-01-01

The major goal of part I of this study was to compare varying doses and dose rates of whole-body gamma-radiation on lymphoid cells and organs. C57BL/6 mice (n = 75) were exposed to 0, 0.5, 1.5, and 3.0 Gy gamma-rays (60Co) at 1 cGy/min (low-dose rate, LDR) and 80 cGy/min (high-dose rate, HDR) and euthanized 4 days later. A significant dose-dependent loss of spleen mass was observed with both LDR and HDR irradiation; for the thymus this was true only with HDR. Decreasing leukocyte and lymphocyte numbers occurred with increasing dose in blood and spleen at both dose rates. The numbers (not percentages) of CD3+ T lymphocytes decreased in the blood in a dose-dependent manner at both HDR and LDR. Splenic T cell counts decreased with dose only in HDR groups; percentages increased with dose at both dose rates. Dose-dependent decreases occurred in CD4+ T helper and CD8+ T cytotoxic cell counts at HDR and LDR. In the blood the percentages of CD4+ cells increased with increasing dose at both dose rates, whereas in the spleen the counts decreased only in the HDR groups. The percentages of the CD8+ population remained stable in both blood and spleen. CD19+ B cell counts and percentages in both compartments declined markedly with increasing HDR and LDR radiation. NK1.1+ natural killer cell numbers and proportions remained relatively stable. Overall, these data indicate that the observed changes were highly dependent on the dose, but not dose rate, and that cells in the spleen are more affected by dose rate than those in blood. The results also suggest that the response of lymphocytes in different body compartments may be variable.

A photocurrent compensation method of bipolar transistors under high dose rate radiation and its experimental research

International Nuclear Information System (INIS)

Yin Xuesong; Liu Zhongli; Li Chunji; Yu Fang

2005-01-01

Experiment using discrete bipolar transistors has been performed to verify the effect of the photocurrent compensation method. The theory of the dose rate effects of bipolar transistors and the photocurrent compensation method are introduced. The comparison between the response of hardened and unhardened circuits under high dose rate radiation is discussed. The experimental results show instructiveness to the hardness of bipolar integrated circuits under transient radiation. (authors)

On-Line High Dose-Rate Gamma Ray Irradiation Test of the CCD/CMOS Cameras

Energy Technology Data Exchange (ETDEWEB)

Cho, Jai Wan; Jeong, Kyung Min [Korea Atomic Energy Research Institute, Daejeon (Korea, Republic of)

2012-05-15

In this paper, test results of gamma ray irradiation to CCD/CMOS cameras are described. From the CAMS (containment atmospheric monitoring system) data of Fukushima Dai-ichi nuclear power plant station, we found out that the gamma ray dose-rate when the hydrogen explosion occurred in nuclear reactors 1{approx}3 is about 160 Gy/h. If assumed that the emergency response robot for the management of severe accident of the nuclear power plant has been sent into the reactor area to grasp the inside situation of reactor building and to take precautionary measures against releasing radioactive materials, the CCD/CMOS cameras, which are loaded with the robot, serve as eye of the emergency response robot. In the case of the Japanese Quince robot system, which was sent to carry out investigating the unit 2 reactor building refueling floor situation, 7 CCD/CMOS cameras are used. 2 CCD cameras of Quince robot are used for the forward and backward monitoring of the surroundings during navigation. And 2 CCD (or CMOS) cameras are used for monitoring the status of front-end and back-end motion mechanics such as flippers and crawlers. A CCD camera with wide field of view optics is used for monitoring the status of the communication (VDSL) cable reel. And another 2 CCD cameras are assigned for reading the indication value of the radiation dosimeter and the instrument. In the preceding assumptions, a major problem which arises when dealing with CCD/CMOS cameras in the severe accident situations of the nuclear power plant is the presence of high dose-rate gamma irradiation fields. In the case of the DBA (design basis accident) situations of the nuclear power plant, in order to use a CCD/CMOS camera as an ad-hoc monitoring unit in the vicinity of high radioactivity structures and components of the nuclear reactor area, a robust survivability of this camera in such intense gamma-radiation fields therefore should be verified. The CCD/CMOS cameras of various types were gamma irradiated at a

The usefulness of metal markers for CTV-based dose prescription in high-dose-rate interstitial brachytherapy

International Nuclear Information System (INIS)

Yoshida, Ken; Mitomo, Masanori; Nose, Takayuki; Koizumi, Masahiko; Nishiyama, Kinji; Yoshida, Mineo

2002-01-01

We employ a clinical target volume (CTV)-based dose prescription for high-dose-rate (HDR) interstitial brachytherapy. However, it is not easy to define CTV and organs at risk (OAR) from X-ray film or CT scanning. To solve this problem, we have utilized metal markers since October 1999. Moreover, metal markers can help modify dose prescription. By regulating the doses to the metal markers, refining the dose prescription can easily be achieved. In this research, we investigated the usefulness of the metal markers. Between October 1999 and May 2001, 51 patients were implanted with metal markers at Osaka Medical Center for Cancer and Cardiovascular Diseases (OMCC), Osaka National Hospital (ONH) and Sanda City Hospital (SCH). Forty-nine patients (head and neck: 32; pelvis: 11; soft tissue: 3; breast: 3) using metal markers were analyzed. During operation, we implanted 179 metal markers (49 patients) to CTV and 151 markers (26 patients) to OAR. At treatment planning, CTV was reconstructed judging from the metal markers, applicator position and operation records. Generally, we prescribed the tumoricidal dose to an isodose surface that covers CTV. We also planned to limit the doses to OAR lower than certain levels. The maximum normal tissue doses were decided 80%, 150%, 100%, 50% and 200% of the prescribed doses for the rectum, the urethra, the mandible, the skin and the large vessel, respectively. The doses to the metal markers using CTV-based dose prescription were generated. These were compared with the doses theoretically calculated with the Paris system. Treatment results were also investigated. The doses to the 158 metal markers (42 patients) for CTV were higher than ''tumoricidal dose''. In 7 patients, as a result of compromised dose prescription, 9 markers were lower than the tumoricidal dose. The other 12 markers (7%) were excluded from dose evaluation because they were judged as miss-implanted. The doses to the 142 metal markers (24 patients) for OAR were lower

Evaluation of the efficacy and safety of endovascular management for transplant renal artery stenosis

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Leonardo G.M. Valle

Full Text Available OBJECTIVES: To evaluate the safety and efficacy of endovascular intervention with angioplasty and stent placement in patients with transplant renal artery stenosis. METHODS: All patients diagnosed with transplant renal artery stenosis and graft dysfunction or resistant systemic hypertension who underwent endovascular treatment with stenting from February 2011 to April 2016 were included in this study. The primary endpoint was clinical success, and the secondary endpoints were technical success, complication rate and stent patency. RESULTS: Twenty-four patients with transplant renal artery stenosis underwent endovascular treatment, and three of them required reinterventions, resulting in a total of 27 procedures. The clinical success rate was 100%. All graft dysfunction patients showed decreased serum creatinine levels and improved estimated glomerular filtration rates and creatinine levels. Patients with high blood pressure also showed improved control of systemic blood pressure and decreased use of antihypertensive drugs. The technical success rate of the procedure was 97%. Primary patency and assisted primary patency rates at one year were 90.5% and 100%, respectively. The mean follow-up time of patients was 794.04 days after angioplasty. CONCLUSION: Angioplasty with stent placement for the treatment of transplant renal artery stenosis is a safe and effective technique with good results in both the short and long term.

Determination of air kerma standard of high dose rate 192Ir brachytherapy source

International Nuclear Information System (INIS)

Pires, E.J.; Alves, C.F.E.; Leite, S.P.; Magalhaes, L.A.G.; David, M.G.; Almeida, C.E. de

2015-01-01

This paper presents the methodology developed by the Laboratorio de Ciencias Radiologicas and presently in use for determining of the air kerma standard of 192 Ir high dose rate sources to calibrate well-type chambers. Uncertainty analysis involving the measurements procedure are presented. (author)

Dose rate and dose fractionation studies in total body irradiation of dogs

International Nuclear Information System (INIS)

Kolb, H.J.; Netzel, B.; Schaffer, E.; Kolb, H.

1979-01-01

Total body irradiation (TBI) with 800-900 rads and allogeneic bone marrow transplantation according to the regimen designated by the Seattle group has induced remissions in patients with otherwise refractory acute leukemias. Relapse of leukemia after bone marrow transplantation remains the major problem, when the Seattle set up of two opposing 60 Co-sources and a low dose rate is used in TBI. Studies in dogs with TBI at various dose rates confirmed observations in mice that gastrointestinal toxicity is unlike toxicity against hemopoietic stem cells and possibly also leukemic stem cells depending on the dose rate. However, following very high single doses (2400 R) and marrow infusion acute gastrointestinal toxicity was not prevented by the lowest dose rate studied (0.5 R/min). Fractionated TBI with fractions of 600 R in addition to 1200 R (1000 rads) permitted the application of total doses up to 300 R followed by marrow infusion without irreversible toxicity. 26 dogs given 2400-3000 R have been observed for presently up to 2 years with regard to delayed radiation toxicity. This toxicity was mild in dogs given single doses at a low dose rate or fractionated TBI. Fractionated TBI is presently evaluated with allogeneic transplants in the dog before being applied to leukemic patients

Interaction of 2-Gy Equivalent Dose and Margin Status in Perioperative High-Dose-Rate Brachytherapy

International Nuclear Information System (INIS)

Martinez-Monge, Rafael; Cambeiro, Mauricio; Moreno, Marta; Gaztanaga, Miren; San Julian, Mikel; Alcalde, Juan; Jurado, Matias

2011-01-01

Purpose: To determine patient, tumor, and treatment factors predictive of local control (LC) in a series of patients treated with either perioperative high-dose-rate brachytherapy (PHDRB) alone (Group 1) or with PHDRB combined with external-beam radiotherapy (EBRT) (Group 2). Patient and Methods: Patients (n = 312) enrolled in several PHDRB prospective Phase I-II studies conducted at the Clinica Universidad de Navarra were analyzed. Treatment with PHDRB alone, mainly because of prior irradiation, was used in 126 patients to total doses of 32 Gy/8 b.i.d. or 40 Gy/10 b.i.d. treatments after R0 or R1 resections. Treatment with PHDRB plus EBRT was used in 186 patients to total doses of 16 Gy/4 b.i.d. or 24 Gy/6 b.i.d. treatments after R0 or R1 resections along with 45 Gy of EBRT with or without concomitant chemotherapy. Results: No dose-margin interaction was observed in Group 1 patients. In Group 2 patients there was a significant interaction between margin status and 2-Gy equivalent (Eq2Gy) dose (p = 0.002): (1) patients with negative margins had 9-year LC of 95.7% at Eq2Gy = 62.9Gy; (2) patients with close margins of >1 mm had 9-year LC of 92.4% at Eq2Gy = 72.2Gy, and (3) patients with positive/close <1-mm margins had 9-year LC of 68.0% at Eq2Gy = 72.2Gy. Conclusions: Two-gray equivalent doses ≥70 Gy may compensate the effect of close margins ≥1 mm but do not counterbalance the detrimental effect of unfavorable (positive/close <1 mm) resection margins. No dose-margin interaction is observed in patients treated at lower Eq2Gy doses ≤50 Gy with PHDRB alone.

Dose and dose rate monitor

International Nuclear Information System (INIS)

Novakova, O.; Ryba, J.; Slezak, V.; Svobodova, B.; Viererbl, L.

1984-10-01

The methods are discussea of measuring dose rate or dose using a scintillation counte. A plastic scintillator based on polystyrene with PBD and POPOP activators and coated with ZnS(Ag) was chosen for the projected monitor. The scintillators were cylindrical and spherical in shape and of different sizes; black polypropylene tubes were chosen as the best case for the probs. For the counter with different plastic scintillators, the statistical error 2σ for natural background was determined. For determining the suitable thickness of the ZnS(Ag) layer the energy dependence of the counter was measured. Radioisotopes 137 Cs, 241 Am and 109 Cd were chosen as radiation sources. The best suited ZnS(Ag) thickness was found to be 0.5 μm. Experiments were carried out to determine the directional dependence of the detector response and the signal to noise ratio. The temperature dependence of the detector response and its compensation were studied, as were the time stability and fatigue manifestations of the photomultiplier. The design of a laboratory prototype of a dose rate and dose monitor is described. Block diagrams are given of the various functional parts of the instrument. The designed instrument is easiiy portable, battery powered, measures dose rates from natural background in the range of five orders, i.e., 10 -2 to 10 3 nGy/s, and allows to determine a dose of up to 10 mGy. Accouracy of measurement in the energy range of 50 keV to 1 MeV is better than +-20%. (E.S.)

Impact of doped boron concentration in emitter on high- and low-dose-rate damage in lateral PNP transistors

International Nuclear Information System (INIS)

Zheng Yuzhan; Lu Wu; Ren Diyuan; Wang Yiyuan; Wang Zhikuan; Yang Yonghui

2010-01-01

The characteristics of radiation damage under a high or low dose rate in lateral PNP transistors with a heavily or lightly doped emitter is investigated. Experimental results show that as the total dose increases, the base current of transistors would increase and the current gain decreases. Furthermore, more degradation has been found in lightly-doped PNP transistors, and an abnormal effect is observed in heavily doped transistors. The role of radiation defects, especially the double effects of oxide trapped charge, is discussed in heavily or lightly doped transistors. Finally, through comparison between the high- and low-dose-rate response of the collector current in heavily doped lateral PNP transistors, the abnormal effect can be attributed to the annealing of the oxide trapped charge. The response of the collector current, in heavily doped PNP transistors under high- and low-dose-rate irradiation is described in detail. (semiconductor integrated circuits)

Late complications after high-dose-rate interstitial brachytherapy for tongue cancer

International Nuclear Information System (INIS)

Shimizutani, Kimishige; Inoue, Takehiro; Inoue, Toshihiko; Yoshioka, Yasuo; Teshima, Teruki; Kakimoto, Naoya; Murakami, Shumei; Furukawa, Souhei; Fuchihata, Hajime

2005-01-01

The objectives of this study was to analyze the treatment results and late complications of high-dose-rate (HDR) interstitial brachytherapy (ISBT) for early (T1N0, T2N0) mobile tongue cancer using the microSelectron-HDR. From January 1993 through April 2001, a total of 72 patients with early squamous cell carcinomas of the mobile tongue were treated with microSelectron-HDR interstitial brachytherapy at the Department of Radiology, Osaka University Hospital. Of the patients, 18% were treated with a combination of prior external radiation and HDR-ISBT, and 82% were treated with HDR-ISBT alone. For HDR-ISBT alone, all cases were treated with a total dose of 54 Gy/9 fractions every 5 days or 60 Gy/10 fractions every 8 days. In combined therapy with an external dose of 30 to 40 Gy, HDR-ISBT was given at a total dose of 42-50 Gy. The Brinkman and alcohol indexes were used to analyze the incidence of late complications after HDR-ISBT. The 2- and 5-year local control rates were 85% and 82%, respectively. Fifteen of 72 patients (21%) treated with HDR-ISBT had late complications. Ten of 15 patients (67%) with late complications had a Brinkman index exceeding 600. HDR-ISBT is useful and easily applied under local anesthesia to early or superficial lesions of the mobile tongue. However, we found an increase in late complications, such as soft-tissue ulcers and bone exposure, after irradiation of tongue cancer with 60 Gy HDR-ISBT in patients with a Brinkman index greater than 600. (author)

Short-term curative effect of endovascular stent-graft treatment for aortic diseases in China: a systematic review.

Directory of Open Access Journals (Sweden)

Siwen Wang

Full Text Available INTRODUCTION: We analyzed the short-term efficacy of endovascular treatment for aortic diseases by summarizing all available published data on endovascular stent-graft treatment for abdominal aortic aneurysm (AAA, thoracic aortic aneurysm (TAA, type A aortic dissection (type A AD and type B aortic dissection (type B AD in China. METHODS: We performed a systematic analysis of 935 published series on retrograde endovascular treatment for aortic diseases in China from January 1996 to November 2010. Based on the inclusion criteria, 159 studies, involving a total of 5531 patients, were included. RESULTS: There were no significant differences in procedural success among the studies (P>0.05. The rates of overall neurologic complications and stroke were significantly different in all two-group comparisons (P0.05. A significant difference was noted between the 30-day mortality rate of the type A AD patients and the AAA or type B AD patients (P<0.05. CONCLUSION: Endovascular stent-graft is a feasible and safe treatment for aortic diseases, with high procedural success and low incidences of post-procedural complications and short-term mortality. Endovascular treatment for AAA and type B AD is more efficient than for type A AD and TAA.

Dosimetric and radiobiological comparison of volumetric modulated arc therapy, high-dose rate brachytherapy, and low-dose rate permanent seeds implant for localized prostate cancer

Energy Technology Data Exchange (ETDEWEB)

Yang, Ruijie, E-mail: ruijyang@yahoo.com; Zhao, Nan; Liao, Anyan; Wang, Hao; Qu, Ang

2016-10-01

To investigate the dosimetric and radiobiological differences among volumetric modulated arc therapy (VMAT), high-dose rate (HDR) brachytherapy, and low-dose rate (LDR) permanent seeds implant for localized prostate cancer. A total of 10 patients with localized prostate cancer were selected for this study. VMAT, HDR brachytherapy, and LDR permanent seeds implant plans were created for each patient. For VMAT, planning target volume (PTV) was defined as the clinical target volume plus a margin of 5 mm. Rectum, bladder, urethra, and femoral heads were considered as organs at risk. A 78 Gy in 39 fractions were prescribed for PTV. For HDR and LDR plans, the dose prescription was D{sub 90} of 34 Gy in 8.5 Gy per fraction, and 145 Gy to clinical target volume, respectively. The dose and dose volume parameters were evaluated for target, organs at risk, and normal tissue. Physical dose was converted to dose based on 2-Gy fractions (equivalent dose in 2 Gy per fraction, EQD{sub 2}) for comparison of 3 techniques. HDR and LDR significantly reduced the dose to rectum and bladder compared with VMAT. The D{sub mean} (EQD{sub 2}) of rectum decreased 22.36 Gy in HDR and 17.01 Gy in LDR from 30.24 Gy in VMAT, respectively. The D{sub mean} (EQD{sub 2}) of bladder decreased 6.91 Gy in HDR and 2.53 Gy in LDR from 13.46 Gy in VMAT. For the femoral heads and normal tissue, the mean doses were also significantly reduced in both HDR and LDR compared with VMAT. For the urethra, the mean dose (EQD{sub 2}) was 80.26, 70.23, and 104.91 Gy in VMAT, HDR, and LDR brachytherapy, respectively. For localized prostate cancer, both HDR and LDR brachytherapy were clearly superior in the sparing of rectum, bladder, femoral heads, and normal tissue compared with VMAT. HDR provided the advantage in sparing of urethra compared with VMAT and LDR.

Dosimetric and radiobiological comparison of volumetric modulated arc therapy, high-dose rate brachytherapy, and low-dose rate permanent seeds implant for localized prostate cancer

International Nuclear Information System (INIS)

Yang, Ruijie; Zhao, Nan; Liao, Anyan; Wang, Hao; Qu, Ang

2016-01-01

To investigate the dosimetric and radiobiological differences among volumetric modulated arc therapy (VMAT), high-dose rate (HDR) brachytherapy, and low-dose rate (LDR) permanent seeds implant for localized prostate cancer. A total of 10 patients with localized prostate cancer were selected for this study. VMAT, HDR brachytherapy, and LDR permanent seeds implant plans were created for each patient. For VMAT, planning target volume (PTV) was defined as the clinical target volume plus a margin of 5 mm. Rectum, bladder, urethra, and femoral heads were considered as organs at risk. A 78 Gy in 39 fractions were prescribed for PTV. For HDR and LDR plans, the dose prescription was D 90 of 34 Gy in 8.5 Gy per fraction, and 145 Gy to clinical target volume, respectively. The dose and dose volume parameters were evaluated for target, organs at risk, and normal tissue. Physical dose was converted to dose based on 2-Gy fractions (equivalent dose in 2 Gy per fraction, EQD 2 ) for comparison of 3 techniques. HDR and LDR significantly reduced the dose to rectum and bladder compared with VMAT. The D mean (EQD 2 ) of rectum decreased 22.36 Gy in HDR and 17.01 Gy in LDR from 30.24 Gy in VMAT, respectively. The D mean (EQD 2 ) of bladder decreased 6.91 Gy in HDR and 2.53 Gy in LDR from 13.46 Gy in VMAT. For the femoral heads and normal tissue, the mean doses were also significantly reduced in both HDR and LDR compared with VMAT. For the urethra, the mean dose (EQD 2 ) was 80.26, 70.23, and 104.91 Gy in VMAT, HDR, and LDR brachytherapy, respectively. For localized prostate cancer, both HDR and LDR brachytherapy were clearly superior in the sparing of rectum, bladder, femoral heads, and normal tissue compared with VMAT. HDR provided the advantage in sparing of urethra compared with VMAT and LDR.

Endovascular image-guided interventions (EIGIs)

International Nuclear Information System (INIS)

Rudin, Stephen; Bednarek, Daniel R.; Hoffmann, Kenneth R.

2008-01-01

Minimally invasive interventions are rapidly replacing invasive surgical procedures for the most prevalent human disease conditions. X-ray image-guided interventions carried out using the insertion and navigation of catheters through the vasculature are increasing in number and sophistication. In this article, we offer our vision for the future of this dynamic field of endovascular image-guided interventions in the form of predictions about (1) improvements in high-resolution detectors for more accurate guidance, (2) the implementation of high-resolution region of interest computed tomography for evaluation and planning, (3) the implementation of dose tracking systems to control patient radiation risk, (4) the development of increasingly sophisticated interventional devices, (5) the use of quantitative treatment planning with patient-specific computer fluid dynamic simulations, and (6) the new expanding role of the medical physicist. We discuss how we envision our predictions will come to fruition and result in the universal goal of improved patient care.

Time-driven activity-based costing of low-dose-rate and high-dose-rate brachytherapy for low-risk prostate cancer.

Science.gov (United States)

Ilg, Annette M; Laviana, Aaron A; Kamrava, Mitchell; Veruttipong, Darlene; Steinberg, Michael; Park, Sang-June; Burke, Michael A; Niedzwiecki, Douglas; Kupelian, Patrick A; Saigal, Christopher

Cost estimates through traditional hospital accounting systems are often arbitrary and ambiguous. We used time-driven activity-based costing (TDABC) to determine the true cost of low-dose-rate (LDR) and high-dose-rate (HDR) brachytherapy for prostate cancer and demonstrate opportunities for cost containment at an academic referral center. We implemented TDABC for patients treated with I-125, preplanned LDR and computed tomography based HDR brachytherapy with two implants from initial consultation through 12-month followup. We constructed detailed process maps for provision of both HDR and LDR. Personnel, space, equipment, and material costs of each step were identified and used to derive capacity cost rates, defined as price per minute. Each capacity cost rate was then multiplied by the relevant process time and products were summed to determine total cost of care. The calculated cost to deliver HDR was greater than LDR by $2,668.86 ($9,538 vs. $6,869). The first and second HDR treatment day cost $3,999.67 and $3,955.67, whereas LDR was delivered on one treatment day and cost $3,887.55. The greatest overall cost driver for both LDR and HDR was personnel at 65.6% ($4,506.82) and 67.0% ($6,387.27) of the total cost. After personnel costs, disposable materials contributed the second most for LDR ($1,920.66, 28.0%) and for HDR ($2,295.94, 24.0%). With TDABC, the true costs to deliver LDR and HDR from the health system perspective were derived. Analysis by physicians and hospital administrators regarding the cost of care afforded redesign opportunities including delivering HDR as one implant. Our work underscores the need to assess clinical outcomes to understand the true difference in value between these modalities. Copyright © 2016 American Brachytherapy Society. Published by Elsevier Inc. All rights reserved.

Preoperative methylprednisolone enhances recovery after endovascular aortic repair

DEFF Research Database (Denmark)

de la Motte, Louise; Kehlet, Henrik; Vogt, Katja

2014-01-01

OBJECTIVE: To evaluate effects of preoperative high-dose glucocorticoid on the inflammatory response and recovery after endovascular aortic aneurysm repair (EVAR). BACKGROUND: The postimplantation syndrome after EVAR may delay recovery due to the release of proinflammatory mediators....... Glucocorticoids may reduce postoperative inflammatory responses and enhance recovery, but with limited information on EVAR. METHODS: A single-center, randomized, double-blind, placebo-controlled trial of 153 patients undergoing elective EVAR between November 2009 and January 2013. Patients received 30 mg.......001) and fulfillment of discharge criteria was shorter [2 days (IQR = 2-4 days) vs 3 days (IQR = 3-4 days)] (P factor receptor were also reduced (P

High dose rate brachytherapy for the palliation of malignant dysphagia

International Nuclear Information System (INIS)

Homs, Marjolein Y.V.; Eijkenboom, Wilhelmina M.H.; Coen, Veronique L.M.A.; Haringsma, Jelle; Blankenstein, Mark van; Kuipers, Ernst J.; Siersema, Peter D.

2003-01-01

Background and purpose: High dose rate (HDR) brachytherapy is a commonly used palliative treatment for esophageal carcinoma. We evaluated the outcome of HDR brachytherapy in patients with malignant dysphagia. Material and methods: A retrospective analysis over a 10-year period was performed of 149 patients treated with HDR brachytherapy, administered in one or two sessions, at a median dose of 15 Gy. Patients were evaluated for functional outcome, complications, recurrent dysphagia, and survival. Results: At 6 weeks after HDR brachytherapy, dysphagia scores had improved from a median of 3 to 2 (n=104; P<0.001), however, dysphagia had not improved in 51 (49%) patients. Procedure-related complications occurred in seven (5%) patients. Late complications, including fistula formation or bleeding, occurred in 11 (7%) patients. Twelve (8%) patients experienced minor retrosternal pain. Median survival of the patients was 160 days with a 1-year survival rate of 15%. Procedure-related mortality was 2%. At follow-up, 55 (37%) patients experienced recurrent dysphagia. In 34 (23%) patients a metal stent was placed to relieve persistent or recurrent dysphagia. Conclusion: HDR brachytherapy is a moderately effective treatment for the palliation of malignant dysphagia. The incidence of early major complications is low, however, persistent and recurrent dysphagia occur frequently, and require often additional treatment

In situ measurements of dose rates from terrestrial gamma rays

International Nuclear Information System (INIS)

Horng, M.C.; Jiang, S.H.

2002-01-01

A portable, high purity germanium (HPGe) detector was employed for the performance of in situ measurements of radionuclide activity concentrations in the ground in Taiwan, at altitudes ranging from sea level to 3900 m. The absolute peak efficiency of the HPGe detector for a gamma-ray source uniformly distributed in the semi-infinite ground was determined using a semi-empirical method. The gamma-ray dose rates from terrestrial radionuclides were calculated from the measured activity levels using recently published dose rate conversion factors. The absorbed dose rate in air due to cosmic rays was derived by subtracting the terrestrial gamma-ray dose rate from the overall absorbed dose rate in air measured using a high-pressure ionization chamber. The cosmic-ray dose rate calculated as a function of altitude, was found to be in good agreement with the data reported by UNSCEAR. (orig.)

Radiation absorbed doses in the event of balloon rupture (BR) during endovascular brachytherapy (EB) using 188Re-perrhenate

International Nuclear Information System (INIS)

Angelides, S.; Hetherington, E.; Karolis, C.; Walker, B.; Jackson, T.; Knittel, T.; Friend, C.; Pitney, M.; Jepson, N.; Milross, C.; Lonergan, D.

2000-01-01

Full text: endovascular brachytherapy (EB) using liquid or solid radiation sources, is an effective emerging therapy for coronary artery disease. Liquid sources provide uniform radiation dose to the vessel wall. However the radiation burden in the unlikely event of BR is not insignificant. The aims of this study were to determine i) absorbed dose for various 188 Re radiopharmaceuticals in the event of BR, and ii) effects of thyroid uptake blocking agent, Lugol's iodine (Ll) and/or bladder catheterisation (BC). Dose calculations were based on MIRDOSE 3.1 with dynamic bladder model and MIRD Dose Estimate Report No.8 for 99 Tc m -pertechnetate, which has similar biokinetic properties to 188 Re-perrhenate. Normal renal function and a bladder voiding interval of 4.8h (1 minute with catheter) were assumed. BR was simulated ex-vivo by puncturing a Solaris angioplasty balloon filled with normal saline at 4 atm. LI, MAG3 and DTPA substantially reduces the radiation dose following BR, particularly to the thyroid, and BC reduces the bladder wall dose. Only the contents of the balloon leaked; 0.4 ml of the total volume of 1.8ml. As binding of 188 Re to ligands is cumbersome, we opted to use LI. Twenty five patients with in-stent re-stenosis have been treated using 188 Re-perrhenate (8 GBq/ml), with no BR. Copyright (2000) The Australian and New Zealand Society of Nuclear Medicine Inc

Rectal dose assessment in patients submitted to high-dose-rate brachytherapy for uterine cervix cancer; Avaliacao da dose no reto em pacientes submetidas a braquiterapia de alta taxa de dose para o tratamento do cancer do colo uterino

Energy Technology Data Exchange (ETDEWEB)

Oliveira, Jetro Pereira de [Universidade Federal do Rio de Janeiro (UFRJ), RJ (Brazil). Faculdade de Medicina; Rosa, Luiz Antonio Ribeiro da [Instituto de Radioprotecao e Dosimetria (IRD/CNEN-RJ), Rio de Janeiro, RJ (Brazil)], e-mail: lrosa@ird.gov.br; Batista, Delano Valdivino Santos; Bardella, Lucia Helena [Instituto Nacional de Cancer (INCA), Rio de Janeiro, RJ (Brazil). Unit of Medical Physics; Carvalho, Arnaldo Rangel [Instituto de Radioprotecao e Dosimetria (IRD/CNEN-RJ), Rio de Janeiro, RJ (Brazil). Lab. of Thermoluminescent Dosimetry

2009-03-15

Objective: The present study was aimed at developing a thermoluminescent dosimetric system capable of assessing the doses delivered to the rectum of patients submitted to high-dose-rate brachytherapy for uterine cervix cancer. Materials and methods: LiF:Mg,Ti,Na powder was the thermoluminescent material utilized for evaluating the rectal dose. The powder was divided into small portions (34 mg) which were accommodated in a capillary tube. This tube was placed into a rectal probe that was introduced into the patient's rectum. Results: The doses delivered to the rectum of six patients submitted to high-dose-rate brachytherapy for uterine cervix cancer evaluated by means of thermoluminescent dosimeters presented a good agreement with the planned values based on two orthogonal (anteroposterior and lateral) radiographic images of the patients. Conclusion: The thermoluminescent dosimetric system developed in the present study is simple and easy to be utilized as compared to other rectal dosimetry methods. The system has shown to be effective in the evaluation of rectal doses in patients submitted to high-dose-rate brachytherapy for uterine cervix cancer. (author)

Biology of dose rate in brachytherapy

International Nuclear Information System (INIS)

Brenner, David J.

1995-01-01

Purpose: This course is designed for practitioners and beginners in brachytherapy. The aim is to review biological principles underlying brachytherapy, to understand why current treatment regimes are the way they are, and to discuss what the future may hold in store. Brachytherapy has a long history. It was suggested as long ago as 1903 by Alexander Graham Bell, and the optimal application of this technique has been a subject of debate ever since. 'Brachy' means 'short', and the essential features of conventional brachytherapy are: positioning of the source a short distance from, or in, the tumor, allowing good dose distributions; short overall treatment times, to counter tumor repopulation; low dose rate, enabling a good therapeutic advantage between tumor control and damage to late-responding tissue. The advantages of good dose distributions speak for themselves; in some situations, as we shall see, computer-based dose optimization can be used to improve them still further. The advantages of short overall times stem from the fact that accelerated repopulation of the tumor typically begins a few weeks after the start of a radiation treatment. If all the radiation can be crammed in before that time, the risks of tumor repopulation can be considerably reduced. In fact even external-beam radiotherapy is moving in this direction, with the use of highly accelerated protocols. The advantages of low dose rate stem from the differential response to fractionation of early- and late-responding tissues. Essentially, lowering the dose rate spares late-responding tissue more than it does early-responding tissue such as tumors. We shall also discuss some recent innovations in the context of the general principles that have been outlined. For example, High dose rate brachytherapy, particularly for the uterine cervix: Does it work? If so, when and why? Use of Ir-192 sources, with a half life of 70 days: Should corrections be made for changing biological effectiveness as the dose

Risk of solid cancer in low dose-rate radiation epidemiological studies and the dose-rate effectiveness factor.

Science.gov (United States)

Shore, Roy; Walsh, Linda; Azizova, Tamara; Rühm, Werner

2017-10-01

Estimated radiation risks used for radiation protection purposes have been based primarily on the Life Span Study (LSS) of atomic bomb survivors who received brief exposures at high dose rates, many with high doses. Information is needed regarding radiation risks from low dose-rate (LDR) exposures to low linear-energy-transfer (low-LET) radiation. We conducted a meta-analysis of LDR epidemiologic studies that provide dose-response estimates of total solid cancer risk in adulthood in comparison to corresponding LSS risks, in order to estimate a dose rate effectiveness factor (DREF). We identified 22 LDR studies with dose-response risk estimates for solid cancer after minimizing information overlap. For each study, a parallel risk estimate was derived from the LSS risk model using matching values for sex, mean ages at first exposure and attained age, targeted cancer types, and accounting for type of dosimetric assessment. For each LDR study, a ratio of the excess relative risk per Gy (ERR Gy -1 ) to the matching LSS ERR risk estimate (LDR/LSS) was calculated, and a meta-analysis of the risk ratios was conducted. The reciprocal of the resultant risk ratio provided an estimate of the DREF. The meta-analysis showed a LDR/LSS risk ratio of 0.36 (95% confidence interval [CI] 0.14, 0.57) for the 19 studies of solid cancer mortality and 0.33 (95% CI 0.13, 0.54) when three cohorts with only incidence data also were added, implying a DREF with values around 3, but statistically compatible with 2. However, the analyses were highly dominated by the Mayak worker study. When the Mayak study was excluded the LDR/LSS risk ratios increased: 1.12 (95% CI 0.40, 1.84) for mortality and 0.54 (95% CI 0.09, 0.99) for mortality + incidence, implying a lower DREF in the range of 1-2. Meta-analyses that included only cohorts in which the mean dose was LDR data provide direct evidence regarding risk from exposures at low dose rates as an important complement to the LSS risk estimates used

Dose-rate effects in external beam radiotherapy redux

International Nuclear Information System (INIS)

Ling, C. Clifton; Gerweck, Leo E.; Zaider, Marco; Yorke, Ellen

2010-01-01

Recent developments in external beam radiotherapy, both in technical advances and in clinical approaches, have prompted renewed discussions on the potential influence of dose-rate on radio-response in certain treatment scenarios. We consider the multiple factors that influence the dose-rate effect, e.g. radical recombination, the kinetics of sublethal damage repair for tumors and normal tissues, the difference in α/β ratio for early and late reacting tissues, and perform a comprehensive literature review. Based on radiobiological considerations and the linear-quadratic (LQ) model we estimate the influence of overall treatment time on radio-response for specific clinical situations. As the influence of dose-rate applies to both the tumor and normal tissues, in oligo-fractionated treatment using large doses per fraction, the influence of delivery prolongation is likely important, with late reacting normal tissues being generally more sensitive to the dose-rate effect than tumors and early reacting tissues. In conventional fractionated treatment using 1.8-2 Gy per fraction and treatment times of 2-10 min, the influence of dose-rate is relatively small. Lastly, the dose-rate effect in external beam radiotherapy is governed by the overall beam-on-time, not by the average linac dose-rate, nor by the instantaneous dose-rate within individual linac pulses which could be as high as 3 x 10 6 MU/min.

Manufacture research of the test equipment to measure the dose rate in high radiation medium

International Nuclear Information System (INIS)

Phan Luong Tuan; Nguyen Van Sy; Nguyen Xuan Vinh; Dang Quang Bao; Nguyen Thanh Hung; Pham Minh Duc; Nguyen Xuan Truong

2017-01-01

Photodiode BPW34 is operated as a low voltage counter tubes. When the radiation rays go into the BPW34,they will create a pairs of electron and hole. If setting the reverse bias in to the BPW34, a pulse is achieved and it can be amplified and processed. The STM32 is the microcontroller family which is developed base on ARM processors. The STM32 incorporated many new features such as ADC, I2C, etc. With the connectional ability to other devices, the STM32 is proving its advantages in the development of equipment.The application of irradiation technology in the economy-society increases widespread as food irradiation, mutant irradiation, etc. Until now the calculation the high dose rate at Hanoi Irradiation Center is identified by the Fricke, ECB dosimeters. The dosimeters must be destroyed in order to serve for dose rate determination. Manufacture research the equipment for dose rate calculation support to determine dose rate directly through the equipment’s signal and this equipment can be used multiple. This equipment can be connected to other devices to control the irradiation process better via signals. (author)

Monte Carlo Dosimetry of the 60Co BEBIG High Dose Rate for Brachytherapy.

Directory of Open Access Journals (Sweden)

Luciana Tourinho Campos

Full Text Available The use of high-dose-rate brachytherapy is currently a widespread practice worldwide. The most common isotope source is 192Ir, but 60Co is also becoming available for HDR. One of main advantages of 60Co compared to 192Ir is the economic and practical benefit because of its longer half-live, which is 5.27 years. Recently, Eckert & Ziegler BEBIG, Germany, introduced a new afterloading brachytherapy machine (MultiSource®; it has the option to use either the 60Co or 192Ir HDR source. The source for the Monte Carlo calculations is the new 60Co source (model Co0.A86, which is referred to as the new BEBIG 60Co HDR source and is a modified version of the 60Co source (model GK60M21, which is also from BEBIG.The purpose of this work is to obtain the dosimetry parameters in accordance with the AAPM TG-43U1 formalism with Monte Carlo calculations regarding the BEBIG 60Co high-dose-rate brachytherapy to investigate the required treatment-planning parameters. The geometric design and material details of the source was provided by the manufacturer and was used to define the Monte Carlo geometry. To validate the source geometry, a few dosimetry parameters had to be calculated according to the AAPM TG-43U1 formalism. The dosimetry studies included the calculation of the air kerma strength Sk, collision kerma in water along the transverse axis with an unbounded phantom, dose rate constant and radial dose function. The Monte Carlo code system that was used was EGSnrc with a new cavity code, which is a part of EGS++ that allows calculating the radial dose function around the source. The spectrum to simulate 60Co was composed of two photon energies, 1.17 and 1.33 MeV. Only the gamma part of the spectrum was used; the contribution of the electrons to the dose is negligible because of the full absorption by the stainless-steel wall around the metallic 60Co. The XCOM photon cross-section library was used in subsequent simulations, and the photoelectric effect, pair

Analysis of final products from the liquid alkanes radiolysis at low dose, low temperature and high dose rate

International Nuclear Information System (INIS)

Tilquin, B.; Doncker, J. de.

1991-01-01

Yields of final products (dimers) from the radiolysis of n-hexane and 2,3-dimethylbutane are studied by capillary chromatographic techniques for trace analysis. Reaction of intermediates with the products, the alkane molecules or impurities, is reduced by using low dose (1 kGy), low temperature (195 K) and high dose rate (LINAC). Temperature is the most important experiment variable; by reducing the temperature, reactions with significant activation energies do not compete with radical-radical termination reactions. Products from LINAC radiolysis provide information about active species (reactive fragment, allylic radical...) which deserve a more detailed examination by direct methods [fr

Clinical outcome after endovascular coil embolization in elderly patients with subarachnoid hemorrhage

International Nuclear Information System (INIS)

Johansson, M.; Cesarini, K.G.; Ronne-Engstroem, E.; Enblad, P.; Norbaeck, O.; Gal, G.; Tovi, M.; Solander, S.; Contant, C.F.

2004-01-01

Subarachnoid hemorrhage (SAH) is not an unusual disease in an elderly population. The clinical outcome has improved over time. It has been suggested that elderly SAH patients would benefit from endovascular aneurysm treatment. The aim of this study was to evaluate technical results and clinical outcome in a series of elderly SAH-patients treated with endovascular coil embolization. Sixty-two patients (≥ 65 years) presenting with aneurysmal SAH underwent early endovascular coil embolization at Uppsala University Hospital between September 1996 and December 2000. In all 62 cases included in the study, endovascular coil embolization was considered the first line of treatment. Admission variables, specific information on technical success, degree of occlusion and procedural complications, and outcome figures were recorded. Clinical grade on admission was Hunt and Hess (H and H) I-II in 39%, H and H III in 27% and H and H IV-V in 34% of the patients. The proportion of posterior circulation aneurysms was 24%. Coil embolization was successfully completed in 94%. The degree of occlusion of the treated aneurysm was complete occlusion in 56%, neck remnant in 21%, residual filling in 11%, other remnant in 5% and not treated in 6%. The rate of procedural complications was 11%. Outcome after 6 months was favorable in 41%, severe disability in 36% and poor in 22%. Favorable outcome was achieved in 57% of the H and H I-II patients, 47% of the H and H III patients and 17% of the H and H IV-V patients. Endovascular aneurysm treatment can be performed in elderly patients with SAH with a high level of technical success, acceptable aneurysm occlusion results, an acceptable rate of procedural complications and fair outcome results. (orig.)

Radiation proctitis after the high dose rate brachytherapy for prostate cancer

International Nuclear Information System (INIS)

Kitano, Masashi; Katsumata, Tomoe; Satoh, Takefumi

2006-01-01

We reviewed the medical records of 12 patients treated for rectal bleeding after high-dose rate brachytherapy for prostate cancer. All patients developed grade 2 proctitis according to the Common Terminology Criteria for Adverse Events (CTCAC) and no patients needed blood transfusion. The patients were treated with argon plasma coagulation (APC) and/or steroid suppositories. The bleeding stopped or improved in 11 patients. Although re-bleeding was noticed in 7 patients the same treatment was effective in 5 patients. (author)

Radiation response of industrial materials: Dose-rate and morphology implications

International Nuclear Information System (INIS)

Berejka, Anthony J.

2007-01-01

Industrial uses of ionizing radiation mostly rely upon high current, high dose-rate (100 kGy/s) electron beam (EB) accelerators. To a lesser extent, industry uses low dose-rate (2.8 x 10 -3 kGy/s) radioactive Cobalt-60 as a gamma source, generally for some rather specific purposes, as medical device sterilization and the treatment of food and foodstuffs. There are nearly nine times as many (∼1400) high current EB units in commercial operation than gamma sources (∼160). However, gamma sources can be easily scaled-down so that much research on materials effects is conducted using gamma radiation. Likewise, laboratories are more likely to have very low beam current and consequently low dose-rate accelerators such as Van de Graaff generators and linear accelerators. With the advent of very high current EB accelerators, X-ray processing has become an industrially viable option. With X-rays from high power sources, dose-rates can be modulated based upon accelerator power and the attenuation of the X-ray by the distance of the material from the X-ray target. Dose and dose-rate dependence has been found to be of consequence in several commercial applications which can employ the use of ionizing radiation. The combination of dose and dose-rate dependence of the polymerization and crosslinking of wood impregnants and of fiber composite matrix materials can yield more economically viable results which have promising commercial potential. Monomer and oligomer structure also play an important role in attaining these desirable results. The influence of morphology is shown on the radiation response of olefin polymers, such as ethylene, propylene and isobutylene polymers and their copolymers. Both controlled morphology and controlled dose-rate have commercial consequences. These are also impacted both by the adroit selection of materials and through the possible use of X-ray processing

Identifying patients with AAA with the highest risk following endovascular repair.

Science.gov (United States)

Cadili, Ali; Turnbull, Robert; Hervas-Malo, Marilou; Ghosh, Sunita; Chyczij, Harold

2012-08-01

It has been demonstrated that endovascular repair of arterial disease results in reduced perioperative morbidity and mortality compared to open surgical repair. The rates of complications and need for reinterventions, however, have been found to be higher than that in open repair. The purpose of this study was to identify the predictors of endograft complications and mortality in patients undergoing endovascular abdominal aortic aneurysm (AAA) repair; specifically, our aim was to identify a subset of patients with AAA whose risk of periprocedure mortality was so high that they should not be offered endovascular repair. We undertook a prospective review of patients with AAA receiving endovascular therapy at a single institution. Collected variables included age, gender, date of procedure, indication for procedure, size of aneurysm (where applicable), type of endograft used, presence of rupture, American Society of Anesthesiologists (ASA) class, major medical comorbidities, type of anesthesia (general, epidural, or local), length of intensive care unit (ICU) stay, and length of hospital stay. These factors were correlated with the study outcomes (overall mortality, graft complications, morbidity, and reintervention) using univariate and multivariate logistic regression. A total of 199 patients underwent endovascular AAA repair during the study period. The ICU stay, again, was significantly correlated with the primary outcomes (death and graft complications). In addition, length of hospital stay greater than 3 days, also emerged as a statistically significant predictor of graft complications in this subgroup (P = .024). Survival analysis for patients with AAA revealed that age over 85 years and ICU stay were predictive of decreased survival. Statistical analysis for other subgroups of patients (inflammatory AAA or dissection) was not performed due to the small numbers in these subgroups. Patients with AAA greater than 85 years of age are at a greater risk of mortality

de novo'' aneurysms following endovascular procedures

International Nuclear Information System (INIS)

Briganti, F.; Cirillo, S.; Caranci, F.; Esposito, F.; Maiuri, F.

2002-01-01

Two personal cases of ''de novo'' aneurysms of the anterior communicating artery (ACoA) occurring 9 and 4 years, respectively, after endovascular carotid occlusion are described. A review of the 30 reported cases (including our own two) of ''de novo'' aneurysms after occlusion of the major cerebral vessels has shown some features, including a rather long time interval after the endovascular procedure of up to 20-25 years (average 9.6 years), a preferential ACoA (36.3%) and internal carotid artery-posterior communicating artery (ICA-PCoA) (33.3%) location of the ''de novo'' aneurysms, and a 10% rate of multiple aneurysms. These data are compared with those of the group of reported spontaneous ''de novo'' aneurysms after SAH or previous aneurysm clipping. We agree that the frequency of ''de novo'' aneurysms after major-vessel occlusion (two among ten procedures in our series, or 20%) is higher than commonly reported (0 to 11%). For this reason, we suggest that patients who have been submitted to endovascular major-vessel occlusion be followed up for up to 20-25 years after the procedure, using non-invasive imaging studies such as MR angiography and high-resolution CT angiography. On the other hand, periodic digital angiography has a questionable risk-benefit ratio; it may be used when a ''de novo'' aneurysm is detected or suspected on non-invasive studies. The progressive enlargement of the ACoA after carotid occlusion, as described in our case 1, must be considered a radiological finding of risk for ''de novo'' aneurysm formation. (orig.)

ELDRS Characterization for a Very High Dose Mission

Science.gov (United States)

Harris, Richard D.; McClure, Steven S.; Rax, Bernard G.; Kenna, Aaron J.; Thorbourn, Dennis O.; Clark, Karla B.; Yan, Tsun-Yee

2010-01-01

Evaluation of bipolar linear parts which may have Enhanced Low Dose Rate Sensitivity (ELDRS) is problematic for missions that have very high dose radiation requirements. The accepted standards for evaluating parts that display ELDRS require testing at a very low dose rate which could be prohibitively long for very high dose missions. In this work, a methodology for ELDRS characterization of bipolar parts for mission doses up to 1 Mrad(Si) is evaluated. The procedure employs an initial dose rate of 0.01 rad(Si)/s to a total dose of 50 krad(Si) and then changes to 0.04 rad(Si)/s to a total dose of 1 Mrad(Si). This procedure appears to work well. No change in rate of degradation with dose has been observed when the dose rate is changed from 0.01 to 0.04 rad(Si)/s. This is taken as an indication that the degradation due to the higher dose rate is equivalent to that at the lower dose rate at the higher dose levels, at least for the parts studied to date. In several cases, significant parameter degradation or functional failure not observed at HDR was observed at fairly high total doses (50 to 250 krad(Si)) at LDR. This behavior calls into question the use of dose rate trend data and enhancement factors to predict LDR performance.

Brachytherapy. High dose rate brachytherapy - Radiation protection: medical sheet ED 4287

International Nuclear Information System (INIS)

Celier, D.; Aubert, B.; Vidal, J.P.; Biau, A.; Lahaye, T.; Gauron, C.; Barret, C.; Boisserie, G.; Branchet, E.; Gambini, D.; Gondran, C.; Le Guen, B.; Guerin, C.; Nguyen, S.; Pierrat, N.; Sarrazin, T.; Donnarieix, D.

2010-02-01

After having indicated the required authorization to implement brachytherapy techniques, this document presents the various aspects and measures related to radiation protection when performing high-dose-rate brachytherapy treatments. It presents the concerned personnel, describes the operational process, indicates the associated hazards and the risk related to ionizing radiation, and describes how the risk is to be assessed and how exposure levels are to be determined (elements of risk assessment, delimitation of controlled and monitored areas, personnel classification, and choice of the dose monitoring method). It describes the various components of a risk management strategy (risk reduction, technical measures regarding the installation and the personnel, training and information, prevention and medical monitoring). It briefly presents how risk management is to be assessed, and mentions other related risks (biological risk, handling and posture, handling of heavy loads, mental workload, chemical risk)

Survival of tumor cells after proton irradiation with ultra-high dose rates

International Nuclear Information System (INIS)

Auer, Susanne; Hable, Volker; Greubel, Christoph; Drexler, Guido A; Schmid, Thomas E; Belka, Claus; Dollinger, Günther; Friedl, Anna A

2011-01-01

Laser acceleration of protons and heavy ions may in the future be used in radiation therapy. Laser-driven particle beams are pulsed and ultra high dose rates of >10 9 Gy s -1 may be achieved. Here we compare the radiobiological effects of pulsed and continuous proton beams. The ion microbeam SNAKE at the Munich tandem accelerator was used to directly compare a pulsed and a continuous 20 MeV proton beam, which delivered a dose of 3 Gy to a HeLa cell monolayer within < 1 ns or 100 ms, respectively. Investigated endpoints were G2 phase cell cycle arrest, apoptosis, and colony formation. At 10 h after pulsed irradiation, the fraction of G2 cells was significantly lower than after irradiation with the continuous beam, while all other endpoints including colony formation were not significantly different. We determined the relative biological effectiveness (RBE) for pulsed and continuous proton beams relative to x-irradiation as 0.91 ± 0.26 and 0.86 ± 0.33 (mean and SD), respectively. At the dose rates investigated here, which are expected to correspond to those in radiation therapy using laser-driven particles, the RBE of the pulsed and the (conventional) continuous irradiation mode do not differ significantly

Emergency endovascular management of peripheral artery aneurysms and pseudoaneurysms – a review

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Gillard Jonathan H

2008-07-01

Full Text Available Abstract Endovascular stenting has been successfully employed in the management of aortic aneurysms; however, its use in managing peripheral arterial conditions remains questionable. We review the utility of endovascular technique in the management of peripheral arterial conditions like aneurysms, pseudoaneurysms and arterio-venous fistulas in the emergency setting. Though long term data about graft patency rates is not yet available, the endovascular approach appears to be a useful minimally invasive technique in situations where open repair is either difficult or not feasible.

A consideration of distributions and treatment schedules in high dose rate intracavitary therapy of carcinoma of the uterine cervix

International Nuclear Information System (INIS)

Sakata, Suoh; Sato, Sigehiro; Nakano, Masao; Iida, Koyo; Yui, Nobuharu

1979-01-01

A remotely controlled afterloading device for high dose rate intracavitary radiation, the remote afterloader Shimadzu Ralstron MTSW-20, was installed at Chiba Cancer Center Hospital in 1973 and put into clinical use for the treatment of carcinoma of the uterine cervix. Before the clinical use, isodose distributions and treatment schedules were investigated, compared with the low dose rate intracavitary radiation by linear sources of 137 Cs used hitherto. The isodose distributions, calculated by using an electronic computer, for various combinations of the length of uterine canal and the separation of vaginal applicators, were the same as those obtained with linear sources. As for the treatment schedules, by using PT (partial tolerance) which was derived from NSD concept of Ellis, a number of fractional radiation regimes with high dose rate, equivalent to continuous low dose rate radiation, was calculated. From these, a dose of 600 rad per fraction to point A every week has been chosen as the standard radiation schedule. The number of fractions has been varied with the clinical stages. Furthermore, some changes of total dose or small modification of dose distribution have been made for individual lesions. According to the preliminary results, three-year cumulative survival rate was 68.7% and complication rate was 15.2%. Comparing these results with those of the treatment at low dose rate, the former is nearly equal, while the latter is lower. The reduction of complication rate is probably due to the improvement of therapeutic techniques such as continuous observation by fractionated intracavitary radiation, variety of isodose distributions and accuracy of source placement by a short treatment time. (author)

Transatlantic Multispecialty Consensus on Fundamental Endovascular Skills: Results of a Delphi Consensus Study.

Science.gov (United States)

Maertens, H; Aggarwal, R; Macdonald, S; Vermassen, F; Van Herzeele, I

2016-01-01

The aim of this study was to establish a consensus on Fundamental Endovascular Skills (FES) for educational purposes and development of training curricula for endovascular procedures. The term "Fundamental Endovascular Skills" is widely used; however, the current literature does not explicitly describe what skills are included in this concept. Endovascular interventions are performed by several specialties that may have opposing perspectives on these skills. A two round Delphi questionnaire approach was used. Experts from interventional cardiology, interventional radiology, and vascular surgery from the United States and Europe were invited to participate. An electronic questionnaire was generated by endovascular therapists with an appropriate educational background but who would not participate in subsequent rounds. The questionnaire consisted of 50 statements describing knowledge, technical, and behavioral skills during endovascular procedures. Experts received the questionnaires by email. They were asked to rate the importance of each skill on a Likert scale from 1 to 5. A statement was considered fundamental when more than 90% of the experts rated it 4 or 5 out of 5. Twenty-three of 53 experts invited agreed to participate: six interventional radiologists (2 USA, 4 Europe), 10 vascular surgeons (4 USA, 6 Europe), and seven interventional cardiologists (4 USA, 3 Europe). There was a 100% response rate in the first round and 87% in the second round. Results showed excellent consensus among responders (Cronbach's alpha = .95 first round; .93 second round). Ninety percent of all proposed skills were considered fundamental. The most critical skills were determined. A transatlantic multispecialty consensus was achieved about the content of "FES" among interventional radiologists, interventional cardiologists, and vascular surgeons from Europe and the United States. These results can serve as directive principles for developing endovascular training curricula

A Matched Case-Control Study on Open and Endovascular Treatment of Popliteal Artery Aneurysms.

Science.gov (United States)

Dorigo, W; Fargion, A; Masciello, F; Piffaretti, G; Pratesi, G; Giacomelli, E; Pratesi, C

2018-01-01

To compare early and late results of open and endovascular management of popliteal artery aneurysm in a retrospective single-center matched case-control study Methods: From 1981 to 2015, 309 consecutive interventions for popliteal artery aneurysm were performed in our institution, in 59 cases with endovascular repair and in 250 cases with open repair. Endovascular repair was preferred in older asymptomatic patients, while open repair was offered more frequently to patients with a thrombosed popliteal artery aneurysm and a poor run-off status. A one-to-one coarsened exact matching on the basis of the baseline demographic, clinical, and anatomical covariates significantly different between the two treatment options was performed and two equivalent groups of 56 endovascular repairs and open repairs were generated. The two groups were compared in terms of perioperative results with χ 2 test and of follow-up outcomes with the Kaplan-Meier curves and log-rank test. There were no differences between the two groups in terms of perioperative outcomes. Median duration of follow-up was 38 months. Five-year survival rates were 94% in endovascular repair group and 89.5% in open repair group (p = 0.4, log-rank 0.6). Primary patency rates at 1, 3, and 5 years were 81%, 78%, and 72% in endovascular repair group and 82.5%, 80%, and 64% in open repair group (p = 0.8, log-rank 0.01). Freedom from reintervention at 5 years was 65.5% in endovascular repair group and 76% in open repair group (p = 0.2, log-rank 1.2). Secondary patency at 1, 3, and 5 years was 94%, 86%, and 74% in endovascular repair group, and 94%, 89%, and 71% in open repair group, respectively (p = 0.9, log-rank 0.01). The rates of limb preservation at 5 years were 94% in endovascular repair group and 86.4% in open repair group (p = 0.3, log-rank 0.8). Open repair and endovascular repair of popliteal artery aneurysms provided in this retrospective single-center experience similar perioperative and follow-up results in

Endovascular treatment of cerebral aneurysms - a cost analysis | Le ...

African Journals Online (AJOL)

The average cost for endovascular treatment per patient was R37 041. Surgical treatment was more expensive at R44 104, a difference of 16%. Conclusions. Despite the high cost of endovascular devices, appropriate use of this technology ultimately offers less expensive treatment than microsurgical clipping of aneurysms.

Modern radiosurgical and endovascular classification schemes for brain arteriovenous malformations.

Science.gov (United States)

Tayebi Meybodi, Ali; Lawton, Michael T

2018-05-04

Stereotactic radiosurgery (SRS) and endovascular techniques are commonly used for treating brain arteriovenous malformations (bAVMs). They are usually used as ancillary techniques to microsurgery but may also be used as solitary treatment options. Careful patient selection requires a clear estimate of the treatment efficacy and complication rates for the individual patient. As such, classification schemes are an essential part of patient selection paradigm for each treatment modality. While the Spetzler-Martin grading system and its subsequent modifications are commonly used for microsurgical outcome prediction for bAVMs, the same system(s) may not be easily applicable to SRS and endovascular therapy. Several radiosurgical- and endovascular-based grading scales have been proposed for bAVMs. However, a comprehensive review of these systems including a discussion on their relative advantages and disadvantages is missing. This paper is dedicated to modern classification schemes designed for SRS and endovascular techniques.

Physics and quality assurance for brachytherapy - Part I: High dose rates

International Nuclear Information System (INIS)

Anderson, Lowell L.

1997-01-01

Purpose: To review the physical aspects of high dose rate (HDR) brachytherapy, including commissioning and quality assurance, source calibration and dose distribution measurements, and treatment planning methods. Following the introduction of afterloading in brachytherapy, development efforts to make it 'remote' culminated in 1964 with the near-simultaneous appearance of remote afterloaders in five major medical centers. Four of these machines were 'high dose rate', three employing 60Co and one (the GammaMed) using a single, cable-mounted 192Ir source. Stepping-motor source control was added to the GammaMed in 1974, making it the precursor of modern remote afterloaders, which are now suitable for interstitial, well as intracavitary brachytherapy by virtue of small source-diameter and indexer-accessed multiple channels. Because the 192Ir sources currently used in HDR remote afterloaders are supplied at a nominal air-kerma strength of 11.4 cGy cm2 s-1 (10 Ci), are not collimated in clinical use, and emit a significant fraction (15%) of photons at energies greater than 600 keV, shielding and facility design must be undertaken as carefully and thoroughly as for external beam installations. Licensing requirements of regulatory agencies must be met with respect both to maximum permissible dose limits and to the existence and functionality of safety devices (door interlocks, radiation monitors, etc.). Commissioning and quality assurance procedures that must be documented for HDR remote afterloading relate to (1) machine, applicator, guide-tube, and facility functionality checks, (2) source calibration, (3) emergency response readiness, (4) planning software evaluation, and (5) independent checks of clinical dose calculations. Source calibration checks must be performed locally, either by in-air measurement of air kerma strength or with a well ionization chamber calibrated (by an accredited standards laboratory) against an in-air measurement of air kerma strength for the

Endovascular approach to treat ascending aortic pseudoaneurysm in a patient with previous CABG and very high surgical risk.

Science.gov (United States)

Zago, Alexandre C; Saadi, Eduardo K; Zago, Alcides J

2011-10-01

Pseudoaneurysm of the ascending aorta is an uncommon pathology and a challenge in high-risk patients who undergo conventional surgery because of high operative morbidity and mortality. Endovascular exclusion of an aortic pseudoaneurysm using an endoprosthesis is a less invasive approach, but few such cases have been reported. Moreover, the use of this approach poses unique therapeutic challenges because there is no specific endoprosthesis for ascending aortic repair, particularly to treat patients with previous coronary artery bypass graft (CABG). We describe the case of a 74-year-old patient who had undergone CABG and later presented with an iatrogenic ascending aortic pseudoaneurysm that occurred during an angiography. This patient was at very high risk for surgical treatment and, therefore, an endovascular approach was adopted: percutaneous coronary intervention for the left main coronary artery, left anterior descending and left circumflex native coronary arteries followed by endovascular endoprosthesis deployment in the ascending aorta to exclude the pseudoaneurysm. Both procedures were successfully performed, and the patient was discharged without complications 4 days later. At 5 months' clinical follow-up, his clinical condition was good and he had no complications. Copyright © 2011 Wiley-Liss, Inc.

Tank Z-361 dose rate calculations

International Nuclear Information System (INIS)

Richard, R.F.

1998-01-01

Neutron and gamma ray dose rates were calculated above and around the 6-inch riser of tank Z-361 located at the Plutonium Finishing Plant. Dose rates were also determined off of one side of the tank. The largest dose rate 0.029 mrem/h was a gamma ray dose and occurred 76.2 cm (30 in.) directly above the open riser. All other dose rates were negligible. The ANSI/ANS 1991 flux to dose conversion factor for neutrons and photons were used in this analysis. Dose rates are reported in units of mrem/h with the calculated uncertainty shown within the parentheses

Complications of endovascular treatment of cerebral aneurysms

Energy Technology Data Exchange (ETDEWEB)

Orrù, Emanuele, E-mail: surgeon.ema@gmail.com [Neuroradiology Department, Padua University Hospital, Via Giustiniani 2, Padua 35128 (Italy); Roccatagliata, Luca, E-mail: lroccatagliata@neurologia.unige.it [Neuroradiology Department, IRCCS San Martino University Hospital and IST, Largo Rosanna Benzi 10, Genoa 16132 (Italy); Department of Health Sciences (DISSAL), University of Genoa (Italy); Cester, Giacomo, E-mail: giacomo.cester@sanita.padova.it [Neuroradiology Department, Padua University Hospital, Via Giustiniani 2, Padua 35128 (Italy); Causin, Francesco, E-mail: francesco.causin@sanita.padova.it [Neuroradiology Department, Padua University Hospital, Via Giustiniani 2, Padua 35128 (Italy); Castellan, Lucio, E-mail: lucio.castellan@hsanmartino.it [Neuroradiology Department, IRCCS San Martino University Hospital and IST, Largo Rosanna Benzi 10, Genoa 16132 (Italy)

2013-10-01

The number of neuroendovascular treatments of both ruptured and unruptured aneurysms has increased substantially in the last two decades. Complications of endovascular treatments of cerebral aneurysms are rare but can potentially lead to acute worsening of the neurological status, to new neurological deficits or death. Some of the possible complications, such as vascular access site complications or systemic side effects associated with contrast medium (e.g. contrast medium allergy, contrast induced nephropathy) can also be encountered in diagnostic angiography. The most common complications of endovascular treatment of cerebral aneurysms are related to acute thromboembolic events and perforation of the aneurysm. Overall, the reported rate of thromboembolic complications ranges between 4.7% and 12.5% while the rate of intraprocedural rupture of cerebral aneurysms is about 0.7% in patients with unruptured aneurysms and about 4.1% in patients with previously ruptured aneurysms. Thromboembolic and hemorrhagic complications may occur during different phases of endovascular procedures and are related to different technical, clinical and anatomic reasons. A thorough knowledge of the different aspects of these complications can reduce the risk of their occurrence and minimize their clinical sequelae. A deep understanding of complications and of their management is thus part of the best standard of care.

Biological effect of Pulsed Dose Rate brachytherapy with stepping sources

International Nuclear Information System (INIS)

Limbergen, Erik F.M. van; Fowler, Jack F.

1996-01-01

Purpose: To explore the possible increase of radiation effect in tissues irradiated by pulsed brachytherapy (PDR), for local tissue dose-rates between those 'averaged over the whole pulse' and the instantaneous high dose rates close to the dwell positions. An earlier publication (Fowler and Mount 1992) had shown that, for dose rates (averaged for the duration of the pulse) up to 3 Gy/h, little change of isoeffect doses from continuous low dose rate (CLDR) are expected, unless larger doses per fraction than 1 Gy are used, and especially if components of very rapid repair are present with half-times of less than about 0.5 hours. However, local and transient dose rates close to stepping sources can be up to several Gy per minute. Methods: Calculations were done assuming the linear quadratic formula for radiation damage, in which only the dose-squared term is subject to repair, at a constant exponential rate. The formula developed by Dale for fractionated low-dose-rate radiotherapy was used. A constant overall time of 140 hours and constant total dose of 70 Gy were assumed throughout, the continuous low dose-rate of 0.5 Gy/h (CLDR) providing the unitary standard effects for each PDR condition. Effects of dose-rates ranging from 4 Gy/h to 120 Gy/h (HDR at 2 Gy/min) were studied, and T (1(2)) from 4 minutes to 1.5 hours. Results: Curves are presented relating the ratio of increased biological effect (proportional to log cell kill) calculated for PDR relative to CLDR. Ratios as high as 1.5 can be found for large doses per pulse (> 1 Gy) at high instantaneous dose-rates if T (1(2)) in tissues is as short as a few minutes. The major influences on effect are dose per pulse, half-time of repair in the tissue, and - when T (1(2)) is short - the instantaneous dose-rate. Maximum ratios of PDR/CLDR effect occur when the dose-rate is such that pulse duration is approximately equal to T (1(2)) of repair. Results are presented for late-responding tissues, the differences from CLDR

High dose-rate brachytherapy source position quality assurance using radiochromic film

International Nuclear Information System (INIS)

Evans, M.D.C.; Devic, S.; Podgorsak, E.B.

2007-01-01

Traditionally, radiographic film has been used to verify high-dose-rate brachytherapy source position accuracy by co-registering autoradiographic and diagnostic images of the associated applicator. Filmless PACS-based clinics that do not have access to radiographic film and wet developers may have trouble performing this quality assurance test in a simple and practical manner. We describe an alternative method for quality assurance using radiochromic-type film. In addition to being easy and practical to use, radiochromic film has some advantages in comparison with traditional radiographic film when used for HDR brachytherapy quality assurance

High dose rate brachytherapy for superficial cancer of the esophagus

International Nuclear Information System (INIS)

Maingon, Philippe; D'Hombres, Anne; Truc, Gilles; Barillot, Isabelle; Michiels, Christophe; Bedenne, Laurent; Horiot, Jean Claude

2000-01-01

Purpose: We analyzed our experience with external radiotherapy, combined modality treatment, or HDR brachytherapy alone to limited esophageal cancers. Methods and Materials: From 1991 to 1996, 25 patients with limited superficial esophagus carcinomas were treated by high dose rate brachytherapy. The mean age was 63 years (43-86 years). Five patients showed superficial local recurrence after external radiotherapy. Eleven patients without invasion of the basal membrane were staged as Tis. Fourteen patients with tumors involving the submucosa without spreading to the muscle were staged as T1. Treatment consisted of HDR brachytherapy alone in 13 patients, external radiotherapy and brachytherapy in 8 cases, and concomitant chemo- and radiotherapy in 4 cases. External beam radiation was administered to a total dose of 50 Gy using 2 Gy daily fractions in 5 weeks. In cases of HDR brachytherapy alone (13 patients), 6 applications were performed once a week. Results: The mean follow-up is 31 months (range 24-96 months). Twelve patients received 2 applications and 13 patients received 6 applications. Twelve patients experienced a failure (48%), 11/12 located in the esophagus, all of them in the treated volume. One patient presented an isolated distant metastasis. In the patients treated for superficial recurrence, 4/5 were locally controlled (80%) by brachytherapy alone. After brachytherapy alone, 8/13 patients were controlled (61%). The mean disease-free survival is 14 months (1-36 months). Overall survival is 76% at 1 year, 37% at 2 years, and 14% at 3 years. Overall survival for Tis patients is 24% vs. 20% for T1 (p 0.83). Overall survival for patients treated by HDR brachytherapy alone is 43%. One patient presented with a fistula with local failure after external radiotherapy and brachytherapy. Four stenosis were registered, two were diagnosed on barium swallowing without symptoms, and two required dilatations. Conclusion: High dose rate brachytherapy permits the treating

Estimation of dose from chromosome aberration rate

International Nuclear Information System (INIS)

Li Deping

1990-01-01

The methods and skills of evaluating dose from correctly scored shromsome aberration rate are presented, and supplemented with corresponding BASIC computer code. The possibility and preventive measures of excessive probability of missing score of the aberrations in some of the current routine score methods are discussed. The use of dose-effect relationship with exposure time correction factor G in evaluating doses and their confidence intervals, dose estimation in mixed n-γ exposure, and identification of high by nonuniform acute exposure to low LET radiation and its dose estimation are discussed in more detail. The difference of estimated dose due to whether the interaction between subleisoms produced by n and γ have been taken into account is examined. In fitting the standard dose-aberration rate curve, proper weighing of experiment points and comparison with commonly accepted values are emphasised, and the coefficient of variation σ y √y of the aberration rate y as a function of dose and exposure time is given. In appendix I and II, the dose-aberration rate formula is derived from dual action theory, and the time variation of subleisom is illustrated and in appendix III, the estimation of dose from scores of two different types of aberrations (of other related score) is illustrated. Two computer codes are given in appendix IV, one is a simple code, the other a complete code, including the fitting of standard curve. the skills of using compressed data storage, and the production of simulated 'data ' for testing the curve fitting procedure are also given

Late effects of post-high-dose-rate brachytherapy for oropharyngeal carcinoma: are they severer than post-low-dose-rate?

International Nuclear Information System (INIS)

Nose, T.; Koizumi, M.; Nishiyama, K.; Peiffert, D.; Lapeyre, M.; Hoffstetter, S.

2004-01-01

Background: late effects by high-dose-rate (HDR) brachytherapy have been believed severer than low-dose-rate (LDR) provided tumor control was constant. Local control of oropharyngeal carcinoma with HDR at Osaka Medical Center was comparable to LDR series from Centre Alexis Vautrin (82%, 79.5%, respectively). To assess the feasibility of HDR brachytherapy, the late effects were compared. Patients and methods: the data of 29 HDR and 24 LDR patients (median follow-up of 27 and 29.5 months, respectively; p = 0.89) were collected. The HDR schedule was 21 Gy/3.5 fractions/2 days following 46 Gy/23 fractions external beam, while 25 Gy/3 days following 50 Gy/25 fractions external beam was for LDR. Late changes were evaluated using RTOG/EORTC late morbidity scoring scheme. For subclinical late changes, mucosa chapter of Dische score was modified for brachytherapy. Scores were discussed through photos and were agreed on by authors. Late sequelae were estimated, by reviewing charts, concerning frequency, severity, and duration of mucosal damages (erosion and ulcer). Results: Late changes were of no difference (p = 0.12 for EORTC/RTOG, and p = 0.45, 0.47, 1.00, 0.12, 0.16, 0.95, 0.27, 0.21 for erythema, ulceration, edema, thinning, pallor, telangiectasia, mobility impairment of tongue/faucial pillars, respectively, of the modified Dische score). Late sequelae showed no differences (p = 0.90, 0.12, 0.40 for frequency, severity, duration, respectively, of mucosal damages). Conclusion: the late effects by HDR were not severer than by LDR. HDR oropharyngeal brachytherapy is as safe as LDR. (orig.)

Breast-Conservative Surgery With Close or Positive Margins: Can the Breast Be Preserved With High-Dose-Rate Brachytherapy Boost?

International Nuclear Information System (INIS)

Guinot, Jose Luis; Roldan, Susana; Maronas, Maria; Tortajada, Isabel; Carrascosa, Maria; Chust, Maria Luisa; Estornell, Marian; Mengual, Jose Luis; Arribas, Leoncio

2007-01-01

Purpose: To evaluate the likelihood of preserving the breast in women who show close or positive margins after conservative surgery for early breast carcinoma. Methods and Materials: Since 1996, 125 women with less than 5 mm or positive margins and positive separate cavity margin sampling were entered in a prospective trial with high-dose radiotherapy. A standard dose of 50 Gy to the whole breast was followed by a high-dose-rate brachytherapy application delivering 3 fractions of 4.4 Gy in 24 hours. The median follow-up was 84 months. Results: There were only seven local recurrences, with an actuarial local control rate of 95.8% at 5 years and 91.1% at 9 years. Actuarial overall and cause-specific survival rates were 92.6% and 95% at 5 years and 86.7% and 90.4% at 9 years, respectively. Late fibrosis was the most common complication, in 30% of patients, with good or excellent cosmetic results in 77%. The final result was that 95.2% of breasts were preserved. Conclusions: Close or positive-margin breast cancer can be well managed with a high-dose boost in a wide tumor bed by means of high-dose-rate brachytherapy. This technique can avoid mastectomy or poor cosmetic resection, with minimal risk of local or general failure

Aneurisma de la aorta abdominal: Tratamiento endovascular con una endoprótesis fenestrada Abdominal aortic aneurysm: Endovascular treatment with fenestrated endoprothesis

Directory of Open Access Journals (Sweden)

Román Rostagno

2008-12-01

Full Text Available El tratamiento endovascular de los aneurismas de aorta abdominal es una alternativa a la cirugía abierta para pacientes de alto riesgo. Consiste en la exclusión del saco aneurismático mediante la interposición de una endoprótesis colocada por vía femoral. El tratamiento endovascular no puede ser utilizado en todos los pacientes. Una limitación frecuente la constituye el nacimiento de una arteria visceral desde el saco aneurismático. Para contrarrestar esta limitación recientemente se han desarrollado endoprótesis fenestradas que presentan orificios que se corresponden con el nacimiento de las arterias involucradas en el aneurisma evitando su oclusión, permitiendo de esta manera el tratamiento endovascular. En esta comunicación se presenta un caso de tratamiento endovascular de un aneurisma de aorta abdominal mediante la colocación de una endoprótesis fenestrada en un paciente cuya arteria renal izquierda nacía directamente del saco aneurismático.Endovascular treatment of the abdominal aortic aneurysm is consider an alternative to open surgery for high risk patients. Its goal is to exclude the aneurysm from the circulation by using an endoprothesis introduced from a femoral approach. Patients must be strictly selected to avoid possible complications. The most frequent limitation is related to anatomic contraindications such as visceral arteries involved in the aneurysm. Fenestrated endograft have been recently developed to allow endovascular treatment when anatomic features contraindicate classic endovascular procedures. Fenestrated endograft have holes that match with the origin of the visceral arteries maintaining its potency. In this paper we report the endovascular treatment of an abdominal aortic aneurysm by using a fenestrated endoprothesis in a patient whose left renal artery is originated from the aneurysm.

Dose/dose-rate responses of shrimp larvae to UV-B radiation

International Nuclear Information System (INIS)

Damkaer, D.M.

1981-01-01

Previous work indicated dose-rate thresholds in the effects of UV-B on the near-surface larvae of three shrimp species. Additional observations suggest that the total dose response varies with dose-rate. Below 0.002 Wm -2 sub([DNA]) irradiance no significant effect is noted in activity, development, or survival. Beyond that dose-rate threshold, shrimp larvae are significantly affected if the total dose exceeds about 85 Jm -2 sub([DNA]). Predictions cannot be made without both the dose-rate and the dose. These dose/dose-rate thresholds are compared to four-year mean dose/dose-rate solar UV-B irradiances at the experimental site, measured at the surface and calculated for 1 m depth. The probability that the shrimp larvae would receive lethal irradiance is low for the first half of the season of surface occurrence, even with a 44% increase in damaging UV radiation. (orig.)

Dose/dose-rate responses of shrimp larvae to UV-B radiation

Energy Technology Data Exchange (ETDEWEB)

Damkaer, D.M.; Dey, D.B.; Heron, G.A.

1981-01-01

Previous work indicated dose-rate thresholds in the effects of UV-B on the near-surface larvae of three shrimp species. Additional observations suggest that the total dose response varies with dose-rate. Below 0.002 Wm/sup -2/sub((DNA)) irradiance no significant effect is noted in activity, development, or survival. Beyond that dose-rate threshold, shrimp larvae are significantly affected if the total dose exceeds about 85 Jm/sup -2/sub((DNA)). Predictions cannot be made without both the dose-rate and the dose. These dose/dose-rate thresholds are compared to four-year mean dose/dose-rate solar UV-B irradiances at the experimental site, measured at the surface and calculated for 1 m depth. The probability that the shrimp larvae would receive lethal irradiance is low for the first half of the season of surface occurrence, even with a 44% increase in damaging UV radiation.

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

Energy Technology Data Exchange (ETDEWEB)

Georg, Dietmar, E-mail: Dietmar.Georg@akhwien.at [Department of Radiation Oncology, Medical University of Vienna/Allgemeines Krankenhaus der Stadt Wien, Vienna (Austria); Christian Doppler Laboratory for Medical Radiation Research for Radiation Oncology, Medical University of Vienna/Allgemeines Krankenhaus der Stadt Wien, Vienna (Austria); Hopfgartner, Johannes [Department of Radiation Oncology, Medical University of Vienna/Allgemeines Krankenhaus der Stadt Wien, Vienna (Austria); Christian Doppler Laboratory for Medical Radiation Research for Radiation Oncology, Medical University of Vienna/Allgemeines Krankenhaus der Stadt Wien, Vienna (Austria); Gòra, Joanna [Department of Radiation Oncology, Medical University of Vienna/Allgemeines Krankenhaus der Stadt Wien, Vienna (Austria); Kuess, Peter [Department of Radiation Oncology, Medical University of Vienna/Allgemeines Krankenhaus der Stadt Wien, Vienna (Austria); Christian Doppler Laboratory for Medical Radiation Research for Radiation Oncology, Medical University of Vienna/Allgemeines Krankenhaus der Stadt Wien, Vienna (Austria); Kragl, Gabriele [Department of Radiation Oncology, Medical University of Vienna/Allgemeines Krankenhaus der Stadt Wien, Vienna (Austria); Berger, Daniel [Department of Radiation Oncology, Medical University of Vienna/Allgemeines Krankenhaus der Stadt Wien, Vienna (Austria); Christian Doppler Laboratory for Medical Radiation Research for Radiation Oncology, Medical University of Vienna/Allgemeines Krankenhaus der Stadt Wien, Vienna (Austria); Hegazy, Neamat [Department of Radiation Oncology, Medical University of Vienna/Allgemeines Krankenhaus der Stadt Wien, Vienna (Austria); Goldner, Gregor; Georg, Petra [Department of Radiation Oncology, Medical University of Vienna/Allgemeines Krankenhaus der Stadt Wien, Vienna (Austria); Christian Doppler Laboratory for Medical Radiation Research for Radiation Oncology, Medical University of Vienna/Allgemeines Krankenhaus der Stadt Wien, Vienna (Austria)

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

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

International Nuclear Information System (INIS)

Georg, Dietmar; Hopfgartner, Johannes; Gòra, Joanna; Kuess, Peter; Kragl, Gabriele; Berger, Daniel; Hegazy, Neamat; Goldner, Gregor; Georg, Petra

2014-01-01

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 ( 192 Ir) and LDR-BT ( 125 I) were D 90% ≥34 Gy in 8.5 Gy per fraction and D 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 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 were clearly superior in

HDRMC, an accelerated Monte Carlo dose calculator for high dose rate brachytherapy with CT-compatible applicators

Energy Technology Data Exchange (ETDEWEB)

Chibani, Omar, E-mail: omar.chibani@fccc.edu; C-M Ma, Charlie [Fox Chase Cancer Center, Philadelphia, Pennsylvania 19111 (United States)

2014-05-15

Purpose: To present a new accelerated Monte Carlo code for CT-based dose calculations in high dose rate (HDR) brachytherapy. The new code (HDRMC) accounts for both tissue and nontissue heterogeneities (applicator and contrast medium). Methods: HDRMC uses a fast ray-tracing technique and detailed physics algorithms to transport photons through a 3D mesh of voxels representing the patient anatomy with applicator and contrast medium included. A precalculated phase space file for the{sup 192}Ir source is used as source term. HDRM is calibrated to calculated absolute dose for real plans. A postprocessing technique is used to include the exact density and composition of nontissue heterogeneities in the 3D phantom. Dwell positions and angular orientations of the source are reconstructed using data from the treatment planning system (TPS). Structure contours are also imported from the TPS to recalculate dose-volume histograms. Results: HDRMC was first benchmarked against the MCNP5 code for a single source in homogenous water and for a loaded gynecologic applicator in water. The accuracy of the voxel-based applicator model used in HDRMC was also verified by comparing 3D dose distributions and dose-volume parameters obtained using 1-mm{sup 3} versus 2-mm{sup 3} phantom resolutions. HDRMC can calculate the 3D dose distribution for a typical HDR cervix case with 2-mm resolution in 5 min on a single CPU. Examples of heterogeneity effects for two clinical cases (cervix and esophagus) were demonstrated using HDRMC. The neglect of tissue heterogeneity for the esophageal case leads to the overestimate of CTV D90, CTV D100, and spinal cord maximum dose by 3.2%, 3.9%, and 3.6%, respectively. Conclusions: A fast Monte Carlo code for CT-based dose calculations which does not require a prebuilt applicator model is developed for those HDR brachytherapy treatments that use CT-compatible applicators. Tissue and nontissue heterogeneities should be taken into account in modern HDR

Problems in continuous dose rate measurement

International Nuclear Information System (INIS)

Yoshioka, Mitsuo

1983-01-01

The system of continuous dose rate measurement in Fukui Prefecture is described. A telemeter system was constructed in October, 1976, and it has been operated since 1977. Observation has been made at 11 observation stations in the Prefecture. In addition to the continuous measurement of dose rate by using NaI(T1)-DBM systems, the ionization chambers for high dose rate were installed, and also meteorological data have been collected. The detectors are covered with 1 mm thick aluminum designed so that the absorption of external radiation is kept as small as possible. To keep the environmental temperature of the detectors constant, constant temperature wind blow is made. With these consideration, the measurement of Xe-133 is possible, and the standard deviation of yearly dose is around 0.4 mR/Y. By measuring DBM transmission rate, the contribution of Xe-133, which comes from the exhaust pumps in power plants, can be detected. The problems of this system are as follows. First of all, the characteristics of the system must meet the purpose of dose monitoring. The system must detect the dose less than the target value to be achieved. The second is the selection of measuring systems to be set. The system is still not unified, and it is difficult to exchange data between different stations. Finally, the method of data analysis is not yet unified. Manuals or guide-books for this purpose are necessary for the mutual comparison of the data from the stations in different districts. (Kato, T.)

Early quality of life outcomes in patients with prostate cancer managed by high-dose-rate brachytherapy as monotherapy

International Nuclear Information System (INIS)

Komiya, Akira; Fujiuchi, Yasuyoshi; Ito, Takatoshi

2013-01-01

The purpose of this study was to evaluate the early quality of life outcomes in prostate cancer patients managed by high-dose-rate brachytherapy as monotherapy. A total of 51 patients with cT1c-T3aN0M0 prostate cancer treated between July 2007 and January 2010 were included in this study. The average age was 69?years, and the average initial serum prostate-specific antigen was 10.98?ng/mL. A total of 25, 18 and eight patients were considered to be low, intermediate and high risk, respectively. All patients received one implant of Ir-192 and seven fractions of 6.5?Gy within 3.5?days for a total prescribed dose of 45.5?Gy. For high-risk prostate cancer, neoadjuvant androgen deprivation therapy was carried out for at least 6?months, and continued after high-dose-rate brachytherapy. Quality of life outcomes were measured by using the International Prostate Symptom Score, the Functional Assessment of Cancer Therapy-Prostate and the International Index of Erectile Function Questionnaire. The oncological outcome was assessed by serum prostate-specific antigen and diagnostic imaging. Adverse events were also recorded. The Functional Assessment of Cancer Therapy-Prostate scores decreased for a few months after high-dose-rate brachytherapy, and recovered to pretreatment condition thereafter. The International Prostate Symptom Score significantly increased 2?weeks after treatment for each of its items and their sum, and it returned to baseline after 12?weeks. Sexual function decreased at 2 and 4?weeks, and recovered after 12?weeks. Severe complications were rare. Within a median follow up of 17.2?months, two patients showed a prostate-specific antigen recurrence. High-dose-rate brachytherapy for prostate cancer is a feasible treatment modality with acceptable toxicity and only a limited impact on the quality of life. (author)

Dose and dose-rate effects of ionizing radiation: a discussion in the light of radiological protection

Energy Technology Data Exchange (ETDEWEB)

Ruehm, Werner [Helmholtz Zentrum Muenchen, German Research Center for Environmental Health, Institute of Radiation Protection, Neuherberg (Germany); Woloschak, Gayle E. [Northwestern University, Department of Radiation Oncology, Feinberg School of Medicine, Chicago, IL (United States); Shore, Roy E. [Radiation Effects Research Foundation (RERF), Hiroshima City (Japan); Azizova, Tamara V. [Southern Urals Biophysics Institute (SUBI), Ozyorsk, Chelyabinsk Region (Russian Federation); Grosche, Bernd [Federal Office for Radiation Protection, Oberschleissheim (Germany); Niwa, Ohtsura [Fukushima Medical University, Fukushima (Japan); Akiba, Suminori [Kagoshima University Graduate School of Medical and Dental Sciences, Department of Epidemiology and Preventive Medicine, Kagoshima City (Japan); Ono, Tetsuya [Institute for Environmental Sciences, Rokkasho, Aomori-ken (Japan); Suzuki, Keiji [Nagasaki University, Department of Radiation Medical Sciences, Atomic Bomb Disease Institute, Nagasaki (Japan); Iwasaki, Toshiyasu [Central Research Institute of Electric Power Industry (CRIEPI), Radiation Safety Research Center, Nuclear Technology Research Laboratory, Tokyo (Japan); Ban, Nobuhiko [Tokyo Healthcare University, Faculty of Nursing, Tokyo (Japan); Kai, Michiaki [Oita University of Nursing and Health Sciences, Department of Environmental Health Science, Oita (Japan); Clement, Christopher H.; Hamada, Nobuyuki [International Commission on Radiological Protection (ICRP), PO Box 1046, Ottawa, ON (Canada); Bouffler, Simon [Public Health England (PHE), Centre for Radiation, Chemical and Environmental Hazards, Chilton, Didcot (United Kingdom); Toma, Hideki [JAPAN NUS Co., Ltd. (JANUS), Tokyo (Japan)

2015-11-15

The biological effects on humans of low-dose and low-dose-rate exposures to ionizing radiation have always been of major interest. The most recent concept as suggested by the International Commission on Radiological Protection (ICRP) is to extrapolate existing epidemiological data at high doses and dose rates down to low doses and low dose rates relevant to radiological protection, using the so-called dose and dose-rate effectiveness factor (DDREF). The present paper summarizes what was presented and discussed by experts from ICRP and Japan at a dedicated workshop on this topic held in May 2015 in Kyoto, Japan. This paper describes the historical development of the DDREF concept in light of emerging scientific evidence on dose and dose-rate effects, summarizes the conclusions recently drawn by a number of international organizations (e.g., BEIR VII, ICRP, SSK, UNSCEAR, and WHO), mentions current scientific efforts to obtain more data on low-dose and low-dose-rate effects at molecular, cellular, animal and human levels, and discusses future options that could be useful to improve and optimize the DDREF concept for the purpose of radiological protection. (orig.)

Endovascular interventional magnetic resonance imaging

International Nuclear Information System (INIS)

Bartels, L W; Bakker, C J G

2003-01-01

Minimally invasive interventional radiological procedures, such as balloon angioplasty, stent placement or coiling of aneurysms, play an increasingly important role in the treatment of patients suffering from vascular disease. The non-destructive nature of magnetic resonance imaging (MRI), its ability to combine the acquisition of high quality anatomical images and functional information, such as blood flow velocities, perfusion and diffusion, together with its inherent three dimensionality and tomographic imaging capacities, have been advocated as advantages of using the MRI technique for guidance of endovascular radiological interventions. Within this light, endovascular interventional MRI has emerged as an interesting and promising new branch of interventional radiology. In this review article, the authors will give an overview of the most important issues related to this field. In this context, we will focus on the prerequisites for endovascular interventional MRI to come to maturity. In particular, the various approaches for device tracking that were proposed will be discussed and categorized. Furthermore, dedicated MRI systems, safety and compatibility issues and promising applications that could become clinical practice in the future will be discussed. (topical review)

Flow and wall shear stress characterization after endovascular aneurysm repair and endovascular aneurysm sealing in an infrarenal aneurysm model.

Science.gov (United States)

Boersen, Johannes T; Groot Jebbink, Erik; Versluis, Michel; Slump, Cornelis H; Ku, David N; de Vries, Jean-Paul P M; Reijnen, Michel M P J

2017-12-01

Endovascular aneurysm repair (EVAR) with a modular endograft has become the preferred treatment for abdominal aortic aneurysms. A novel concept is endovascular aneurysm sealing (EVAS), consisting of dual endoframes surrounded by polymer-filled endobags. This dual-lumen configuration is different from a bifurcation with a tapered trajectory of the flow lumen into the two limbs and may induce unfavorable flow conditions. These include low and oscillatory wall shear stress (WSS), linked to atherosclerosis, and high shear rates that may result in thrombosis. An in vitro study was performed to assess the impact of EVAR and EVAS on flow patterns and WSS. Four abdominal aortic aneurysm phantoms were constructed, including three stented models, to study the influence of the flow divider on flow (Endurant [Medtronic, Minneapolis, Minn], AFX [Endologix, Irvine, Calif], and Nellix [Endologix]). Experimental models were tested under physiologic resting conditions, and flow was visualized with laser particle imaging velocimetry, quantified by shear rate, WSS, and oscillatory shear index (OSI) in the suprarenal aorta, renal artery (RA), and common iliac artery. WSS and OSI were comparable for all models in the suprarenal aorta. The RA flow profile in the EVAR models was comparable to the control, but a region of lower WSS was observed on the caudal wall compared with the control. The EVAS model showed a stronger jet flow with a higher shear rate in some regions compared with the other models. Small regions of low WSS and high OSI were found near the distal end of all stents in the common iliac artery compared with the control. Maximum shear rates in each region of interest were well below the pathologic threshold for acute thrombosis. The different stent designs do not influence suprarenal flow. Lower WSS is observed in the caudal wall of the RA after EVAR and a higher shear rate after EVAS. All stented models have a small region of low WSS and high OSI near the distal outflow

Dose accumulation of multiple high dose rate prostate brachytherapy treatments in two commercially available image registration systems.

Science.gov (United States)

Poder, Joel; Yuen, Johnson; Howie, Andrew; Bece, Andrej; Bucci, Joseph

2017-11-01

The purpose of this study was to assess whether deformable image registration (DIR) is required for dose accumulation of multiple high dose rate prostate brachytherapy (HDRPBT) plans treated with the same catheter pattern on two different CT datasets. DIR was applied to 20 HDRPBT patients' planning CT images who received two treatment fractions on sequential days, on two different CT datasets, with the same implant. Quality of DIR in Velocity and MIM image registration systems was assessed by calculating the Dice Similarity Coefficient (DSC) and mean distance to agreement (MDA) for the prostate, urethra and rectum contours. Accumulated doses from each system were then calculated using the same DIR technique and dose volume histogram (DVH) parameters compared to manual addition with no DIR. The average DSC was found to be 0.83 (Velocity) and 0.84 (MIM), 0.80 (Velocity) and 0.80 (MIM), 0.80 (Velocity) and 0.81 (MIM), for the prostate, rectum and urethra contours, respectively. The average difference in calculated DVH parameters between the two systems using dose accumulation was less than 1%, and there was no statistically significant difference found between deformably accumulated doses in the two systems versus manual DVH addition with no DIR. Contour propagation using DIR in velocity and MIM was shown to be at least equivalent to inter-observer contouring variability on CT. The results also indicate that dose accumulation through manual addition of DVH parameters may be sufficient for HDRPBT treatments treated with the same catheter pattern on two different CT datasets. Crown Copyright © 2017. Published by Elsevier Ltd. All rights reserved.

Preoperative Evaluation and Endovascular Procedure of Intraoperative Aneurysm Rupture During Thoracic Endovascular Aortic Repair

Energy Technology Data Exchange (ETDEWEB)

Zha, Bin-Shan, E-mail: binszha2013@163.com; Zhu, Hua-Gang, E-mail: huagzhu@yeah.net; Ye, Yu-Sheng, E-mail: yeyusheng@aliyun.com; Li, Yong-Sheng, E-mail: 872868848@qq.com; Zhang, Zhi-Gong, E-mail: zzgedward@sina.com; Xie, Wen-Tao, E-mail: 345344347@qq.com [The First Affiliated Hospital of Anhui Medical University, Department of Vascular Surgery (China)

2017-03-15

Thoracic aortic aneurysms are now routinely repaired with endovascular repair if anatomically feasible because of advantages in safety and recovery. However, intraoperative aneurysm rupture is a severe complication which may have an adverse effect on the outcome of treatment. Comprehensive preoperative assessment and considerate treatment are keys to success of endovascular aneurysm repair, especially during unexpected circumstances. Few cases have reported on intraoperative aortic rupture, which were successfully managed by endovascular treatment. Here, we present a rare case of an intraoperative aneurysm rupture during endovascular repair of thoracic aortic aneurysm with narrow neck and angulated aorta arch (coarctation-associated aneurysm), which was successfully treated using double access route approach and iliac limbs of infrarenal devices.Level of EvidenceLevel 5.

A hybrid evolutionary algorithm for multi-objective anatomy-based dose optimization in high-dose-rate brachytherapy

International Nuclear Information System (INIS)

Lahanas, M; Baltas, D; Zamboglou, N

2003-01-01

Multiple objectives must be considered in anatomy-based dose optimization for high-dose-rate brachytherapy and a large number of parameters must be optimized to satisfy often competing objectives. For objectives expressed solely in terms of dose variances, deterministic gradient-based algorithms can be applied and a weighted sum approach is able to produce a representative set of non-dominated solutions. As the number of objectives increases, or non-convex objectives are used, local minima can be present and deterministic or stochastic algorithms such as simulated annealing either cannot be used or are not efficient. In this case we employ a modified hybrid version of the multi-objective optimization algorithm NSGA-II. This, in combination with the deterministic optimization algorithm, produces a representative sample of the Pareto set. This algorithm can be used with any kind of objectives, including non-convex, and does not require artificial importance factors. A representation of the trade-off surface can be obtained with more than 1000 non-dominated solutions in 2-5 min. An analysis of the solutions provides information on the possibilities available using these objectives. Simple decision making tools allow the selection of a solution that provides a best fit for the clinical goals. We show an example with a prostate implant and compare results obtained by variance and dose-volume histogram (DVH) based objectives

Evaluation of the influence of weather conditions on external dose rate

International Nuclear Information System (INIS)

Knight, A.

1993-01-01

Six time periods in 1989/90, when there were high gamma ray dose rate readings at three or more RIMNET Phase 1 sites, were selected for detailed study. The high dose rates were compared with meteorological data (rainfall, temperatures, windspeeds and atmospheric pressure) at the sites for the time periods studied. The results using daily and hourly data clearly show a correlation between gamma ray dose rate and rainfall but not with the other meteorological parameters studied. The increase in dose rate with increased rainfall is believed to be due to radon decay products being washed down with heavy rain. (author)

Response of human fibroblasts to low dose rate gamma irradiation

International Nuclear Information System (INIS)

Dritschilo, A.; Brennan, T.; Weichselbaum, R.R.; Mossman, K.L.

1984-01-01

Cells from 11 human strains, including fibroblasts from patients with the genetic diseases of ataxia telangiectasia (AT), xeroderma pigmentosum (XP), and Fanconi's anemia (FA), were exposed to γ radiation at high (1.6-2.2 Gy/min) and at low (0.03-0.07 Gy/min) dose rates. Survival curves reveal an increase inthe terminal slope (D 0 ) when cells are irradiated at low dose rates compared to high dose rates. This was true for all cell lines tested, although the AT, FA, and XP cells are reported or postulated to have radiation repair deficiencies. From the response of these cells, it is apparent that radiation sensitivities differ; however, at low dose rate, all tested human cells are able to repair injury

Endovascular Management of Patients with Head and Neck Cancers Presenting with Acute Hemorrhage: A Single-Center Retrospective Study

Energy Technology Data Exchange (ETDEWEB)

Vilas Boas, P. P.; Castro-Afonso, L. H. de; Monsignore, L. M.; Nakiri, G. S. [University of São Paulo, Division of Interventional Neuroradiology, Ribeirão Preto Medical School (Brazil); Mello-Filho, F. V. de [University of São Paulo, Department of Ophthalmology, Otorhinolaryngology and Head and Neck Surgery, Ribeirão Preto Medical School (Brazil); Abud, D. G., E-mail: dgabud@fmrp.usp.br [University of São Paulo, Division of Interventional Neuroradiology, Ribeirão Preto Medical School (Brazil)

2017-04-15

PurposeAcute hemorrhage associated with cancers of the head and neck is a life-threatening condition that requires immediate action. The aim of this study was to assess the safety and efficacy of endovascular embolization for acute hemorrhage in patients with head and neck cancers.Materials and MethodsData were retrospectively collected from patients with head and neck cancers who underwent endovascular embolization to treat acute hemorrhage. The primary endpoint was the rate of immediate control of hemorrhage during the first 24 h after embolization. The secondary endpoints were technical or clinical complications, rate of re-hemorrhage 24 h after the procedure, time from embolization to re-hemorrhage, hospitalization time, mortality rate, and time from embolization to death.ResultsFifty-one patients underwent endovascular embolization. The primary endpoint was achieved in 94% of patients. The rate of technical complications was 5.8%, and no clinical complication was observed. Twelve patients (23.5%) had hemorrhage recurrence after an average time of 127.5 days. The average hospitalization time was 7.4 days, the mortality rate during the follow-up period was 66.6%, and the average time from embolization to death was 132.5 days.ConclusionEndovascular embolization to treat acute hemorrhage in patients with head and neck cancers is a safe and effective method for the immediate control of hemorrhage and results in a high rate of hemorrhage control. Larger studies are necessary to determine which treatment strategy is best for improving patient outcomes.

Endovascular Management of Patients with Head and Neck Cancers Presenting with Acute Hemorrhage: A Single-Center Retrospective Study

International Nuclear Information System (INIS)

Vilas Boas, P. P.; Castro-Afonso, L. H. de; Monsignore, L. M.; Nakiri, G. S.; Mello-Filho, F. V. de; Abud, D. G.

2017-01-01

PurposeAcute hemorrhage associated with cancers of the head and neck is a life-threatening condition that requires immediate action. The aim of this study was to assess the safety and efficacy of endovascular embolization for acute hemorrhage in patients with head and neck cancers.Materials and MethodsData were retrospectively collected from patients with head and neck cancers who underwent endovascular embolization to treat acute hemorrhage. The primary endpoint was the rate of immediate control of hemorrhage during the first 24 h after embolization. The secondary endpoints were technical or clinical complications, rate of re-hemorrhage 24 h after the procedure, time from embolization to re-hemorrhage, hospitalization time, mortality rate, and time from embolization to death.ResultsFifty-one patients underwent endovascular embolization. The primary endpoint was achieved in 94% of patients. The rate of technical complications was 5.8%, and no clinical complication was observed. Twelve patients (23.5%) had hemorrhage recurrence after an average time of 127.5 days. The average hospitalization time was 7.4 days, the mortality rate during the follow-up period was 66.6%, and the average time from embolization to death was 132.5 days.ConclusionEndovascular embolization to treat acute hemorrhage in patients with head and neck cancers is a safe and effective method for the immediate control of hemorrhage and results in a high rate of hemorrhage control. Larger studies are necessary to determine which treatment strategy is best for improving patient outcomes.

Beta induced Bremsstrahlung dose rate in concrete shielding

International Nuclear Information System (INIS)

Manjunatha, H.C.

2013-01-01

Dosimetric study of beta-induced Bremsstrahlung in concrete is importance in the field of radiation protection. The efficiency, intensity and dose rate of beta induced Bremsstrahlung by 113 pure beta nuclides in concrete shielding is computed. The Bremsstrahlung dosimetric parameters such as the efficiency (yield), Intensity and dose rate of Bremsstrahlung are low for 199 Au and high for 104 Tc in concrete. The efficiency, Intensity and dose rate of Bremsstrahlung increases with maximum energy of beta nuclide (Emax) and modified atomic number (Zmod) of the target. The estimated Bremsstrahlung efficiency, Intensity and dose rate are useful in the calculations photon track-length distributions. These parameters are useful to determine the quality and quantity of the radiation (known as the source term). Precise estimation of this source term is very important in planning of radiation shielding. (author)

Dose rate effect on material aging due to radiation. [Gamma radiation

Energy Technology Data Exchange (ETDEWEB)

Okamoto, Shin-ichi (Radiation Center of Osaka Prefecture, Sakai (Japan)); Hayakawa, Chikara; Takeya, Chikashi

1982-12-01

Although many reports have been presented on the radiation aging of the organic materials for electric cables, those have been based on the experiments carried out at high dose rate near 1 x 10/sup 6/ rad/h, assuming that aging effect depends on only radiation dose. Therefore, to investigate the aging behaviour in low dose rate range is an important subject to predict their practical life time. In this report, the results of having investigated the aging behaviour of six types of materials are described, (polyethylene for general insulation purpose, chemically cross-linked polyethylene, fire-retardant chemically cross-linked polyethylene, fire-retardant ethylene-propylene rubber, fire-retardant chloro-sulfonated polyethylene for sheaths, and fire-retardant, low hydrochloric acid, special heat-resistant vinyl for insulation purpose or chloroclean). They were irradiated with /sup 60/Co ..gamma..-ray at the dose from 5 x 10/sup 3/ to 1 x 10/sup 6/ rad/h, and their deterioration was tested for the items of elongation, tensile strength, resistivity, dielectric tangent and gel fraction. The aging mechanism and dose rate effect were also considered. The dose rate effect appeared or did not appear depending on the types of materials and also their properties. The materials that showed the dose rate effect included the typical ones whose characteristics degraded with the decreasing dose rate, and the peculiar ones whose deterioration of characteristics did not appear constantly. Aging mechanism may vary in the case of high dose rate and low dose rate. Also, if the life time at respective dose rate in relatively higher dose rate region is clarified, the life time in low dose rate region may possibly be predicted.

Dose-rate dependent stochastic effects in radiation cell-survival models

International Nuclear Information System (INIS)

Sachs, R.K.; Hlatky, L.R.

1990-01-01

When cells are subjected to ionizing radiation the specific energy rate (microscopic analog of dose-rate) varies from cell to cell. Within one cell, this rate fluctuates during the course of time; a crossing of a sensitive cellular site by a high energy charged particle produces many ionizations almost simultaneously, but during the interval between events no ionizations occur. In any cell-survival model one can incorporate the effect of such fluctuations without changing the basic biological assumptions. Using stochastic differential equations and Monte Carlo methods to take into account stochastic effects we calculated the dose-survival rfelationships in a number of current cell survival models. Some of the models assume quadratic misrepair; others assume saturable repair enzyme systems. It was found that a significant effect of random fluctuations is to decrease the theoretically predicted amount of dose-rate sparing. In the limit of low dose-rates neglecting the stochastic nature of specific energy rates often leads to qualitatively misleading results by overestimating the surviving fraction drastically. In the opposite limit of acute irradiation, analyzing the fluctuations in rates merely amounts to analyzing fluctuations in total specific energy via the usual microdosimetric specific energy distribution function, and neglecting fluctuations usually underestimates the surviving fraction. The Monte Carlo methods interpolate systematically between the low dose-rate and high dose-rate limits. As in other approaches, the slope of the survival curve at low dose-rates is virtually independent of dose and equals the initial slope of the survival curve for acute radiation. (orig.)

High-Dose-Rate Monotherapy for Localized Prostate Cancer: 10-Year Results

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Hauswald, Henrik; Kamrava, Mitchell R.; Fallon, Julia M.; Wang, Pin-Chieh; Park, Sang-June; Van, Thanh; Borja, Lalaine; Steinberg, Michael L.; Demanes, D. Jeffrey, E-mail: JDemanes@mednet.ucla.edu

2016-03-15

Purpose: High-dose-rate (HDR) brachytherapy was originally used with external beam radiation therapy (EBRT) to increase the dose to the prostate without injuring the bladder or rectum. Numerous studies have reported HDR brachytherapy is safe and effective. We adapted it for use without EBRT for cases not requiring lymph node treatment. Patients and Methods: We entered the patient demographics, disease characteristics, and treatment parameters into a prospective registry and serially added follow-up data for 448 men with low-risk (n=288) and intermediate-risk (n=160) prostate cancer treated from 1996 to 2009. Their median age was 64 years (range 42-90). The median prostate-specific antigen (PSA) level was 6.0 ng/mL (range 0.2-18.2). The Gleason score was ≤6 in 76% and 7 in 24%. The median dose was 43.5 Gy in 6 fractions. The clinical and biochemical disease control and survival rates were calculated. Adverse events were graded according to the Common Toxicity Criteria of Adverse Events. Results: The median follow-up period was 6.5 years (range 0.3-15.3). The actuarial 6- and 10-year PSA progression-free survival was 98.6% (95% confidence interval [CI] 96.9%-99.4%) and 97.8% (95% CI 95.5%-98.9%). Overall survival at 10 years was 76.7% (95% CI 69.9%-82.2%). The local control, distant metastasis-free survival, and cause-specific survival were 99.7% (95% CI 97.9%-99.9%), 98.9% (95% CI 96.3%-99.7%), and 99.1% (95% CI 95.8%-99.8%). T stage, initial PSA level, Gleason score, National Comprehensive Cancer Network risk group, patient age, and androgen deprivation therapy did not significantly correlate with disease control or survival. No late grade 3 to 4 rectal toxicities developed. Late grade 3 to 4 genitourinary toxicity occurred in 4.9% (grade 3 in 4.7%). Conclusions: HDR monotherapy is a safe and highly effective treatment of low- and intermediate-risk prostate cancer.

Microfluidic thrombosis under multiple shear rates and antiplatelet therapy doses.

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Melissa Li

Full Text Available The mainstay of treatment for thrombosis, the formation of occlusive platelet aggregates that often lead to heart attack and stroke, is antiplatelet therapy. Antiplatelet therapy dosing and resistance are poorly understood, leading to potential incorrect and ineffective dosing. Shear rate is also suspected to play a major role in thrombosis, but instrumentation to measure its influence has been limited by flow conditions, agonist use, and non-systematic and/or non-quantitative studies. In this work we measured occlusion times and thrombus detachment for a range of initial shear rates (500, 1500, 4000, and 10000 s(-1 and therapy concentrations (0-2.4 µM for eptifibatide, 0-2 mM for acetyl-salicylic acid (ASA, 3.5-40 Units/L for heparin using a microfluidic device. We also measured complete blood counts (CBC and platelet activity using whole blood impedance aggregometry. Effects of shear rate and dose were analyzed using general linear models, logistic regressions, and Cox proportional hazards models. Shear rates have significant effects on thrombosis/dose-response curves for all tested therapies. ASA has little effect on high shear occlusion times, even at very high doses (up to 20 times the recommended dose. Under ASA therapy, thrombi formed at high shear rates were 4 times more prone to detachment compared to those formed under control conditions. Eptifibatide reduced occlusion when controlling for shear rate and its efficacy increased with dose concentration. In contrast, the hazard of occlusion from ASA was several orders of magnitude higher than that of eptifibatide. Our results show similar dose efficacy to our low shear measurements using whole blood aggregometry. This quantitative and statistically validated study of the effects of a wide range of shear rate and antiplatelet therapy doses on occlusive thrombosis contributes to more accurate understanding of thrombosis and to models for optimizing patient treatment.

High-dose-rate brachytherapy in the treatment of uterine cervix cancer. Analysis of dose effectiveness and late complications

International Nuclear Information System (INIS)

Ferrigno, Robson; Novaes, Paulo Eduardo Ribeiro dos Santos; Pellizzon, Antonio Cassio Assis; Maia, Maria Aparecida Conte; Fogarolli, Ricardo Cesar; Gentil, Andre Cavalcanti; Salvajoli, Joao Victor

2001-01-01

Purpose: This retrospective analysis aims to report results of patients with cervix cancer treated by external beam radiotherapy (EBR) and high-dose-rate (HDR) brachytherapy. Methods and Materials: From September 1992 to December 1996, 138 patients with FIGO Stages II and III and mean age of 56 years were treated. Median EBR to the whole pelvis was 45 Gy in 25 fractions. Parametrial boost was performed in 93% of patients, with a median dose of 14.4 Gy. Brachytherapy with HDR was performed during EBR or following its completion with a dose of 24 Gy in four weekly fractions of 6 Gy to point A. Median overall treatment time was of 60 days. Patient age, tumor stage, and overall treatment time were variables analyzed for survival and local control. Cumulative biologic effective dose (BED) at rectal and bladder reference points were correlated with late complications in these organs and dose of EBR at parametrium was correlated with small bowel complications. Results: Median follow-up time was 38 months. Overall survival, disease-free survival, and local control at 5 years was 53.7%, 52.7%, and 62%, respectively. By multivariate and univariate analysis, overall treatment time up to 50 days was the only statistically significant adverse variable for overall survival (p=0.003) and actuarial local control (p=0.008). The 5-year actuarial incidence of rectal, bladder, and small bowel late complications was 16%, 11%, and 14%, respectively. Patients treated with cumulative BED at rectum points above 110 Gy 3 and at bladder point above 125 Gy 3 had a higher but not statistically significant 5-year actuarial rate of complications at these organs (18% vs. 12%, p=0.49 and 17% vs. 9%, p=0.20, respectively). Patients who received parametrial doses larger than 59 Gy had a higher 5-year actuarial rate of complications in the small bowel; however, this was not statistically significant (19% vs. 10%, p=0.260). Conclusion: This series suggests that 45 Gy to the whole pelvis combined with

Spontaneous mutation rates and the rate-doubling dose

International Nuclear Information System (INIS)

Von Borstel, R.C.; Moustaccki, E.; Latarjet, R.

1978-01-01

The amount of radiation required to double the frequency of mutations or tumours over the rate of those that occur spontaneously is called the rate-doubling dose. An equivalent concept has been proposed for exposure to other environmental mutagens. The doubling dose concept is predicated on the assumption that all human populations have the same spontaneous mutation rate, and that this spontaneous mutation rate is known. It is now established for prokaryotes and lower eukaryotes that numerous genes control the spontaneous mutation rate, and it is likely that the same is true for human cells as well. Given that the accepted mode of evolution of human populatons is from small, isolated groups of individuals, it seems likely that each population would have a different spontaneous mutation rate. Given that a minimum of twenty genes control or affect the spontaneous mutation rate, and that each of these in turn is susceptible to spontaneously arising or environmentally induced mutations, it seems likely that every individual within a population (except for siblings from identical multiple births) will have a unique spontaneous mutation rate. If each individual in a population does have a different spontaneous mutation rate, the doubling dose concept, in rigorous terms, is fallacious. Therefore, as with other concepts of risk evaluation, the doubling dose concept is subject to criticism. Nevertheless, until we know individual spontaneous mutation rates with precision, and can evaluate risks based on this information, the doubling dose concept has a heuristic value and is needed for practical assessment of risks for defined populations. (author)

Effects of proton radiation dose, dose rate and dose fractionation on hematopoietic cells in mice

International Nuclear Information System (INIS)

Ware, J.H.; Rusek, A.; Sanzari, J.; Avery, S.; Sayers, C.; Krigsfeld, G.; Nuth, M.; Wan, X.S.; Kennedy, A.R.

2010-01-01

The present study evaluated the acute effects of radiation dose, dose rate and fractionation as well as the energy of protons in hematopoietic cells of irradiated mice. The mice were irradiated with a single dose of 51.24 MeV protons at a dose of 2 Gy and a dose rate of 0.05-0.07 Gy/min or 1 GeV protons at doses of 0.1, 0.2, 0.5, 1, 1.5 and 2 Gy delivered in a single dose at dose rates of 0.05 or 0.5 Gy/min or in five daily dose fractions at a dose rate of 0.05 Gy/min. Sham-irradiated animals were used as controls. The results demonstrate a dose-dependent loss of white blood cells (WBCs) and lymphocytes by up to 61% and 72%, respectively, in mice irradiated with protons at doses up to 2 Gy. The results also demonstrate that the dose rate, fractionation pattern and energy of the proton radiation did not have significant effects on WBC and lymphocyte counts in the irradiated animals. These results suggest that the acute effects of proton radiation on WBC and lymphocyte counts are determined mainly by the radiation dose, with very little contribution from the dose rate (over the range of dose rates evaluated), fractionation and energy of the protons.

Effects of proton radiation dose, dose rate and dose fractionation on hematopoietic cells in mice.

Science.gov (United States)

Ware, J H; Sanzari, J; Avery, S; Sayers, C; Krigsfeld, G; Nuth, M; Wan, X S; Rusek, A; Kennedy, A R

2010-09-01

The present study evaluated the acute effects of radiation dose, dose rate and fractionation as well as the energy of protons in hematopoietic cells of irradiated mice. The mice were irradiated with a single dose of 51.24 MeV protons at a dose of 2 Gy and a dose rate of 0.05-0.07 Gy/min or 1 GeV protons at doses of 0.1, 0.2, 0.5, 1, 1.5 and 2 Gy delivered in a single dose at dose rates of 0.05 or 0.5 Gy/min or in five daily dose fractions at a dose rate of 0.05 Gy/min. Sham-irradiated animals were used as controls. The results demonstrate a dose-dependent loss of white blood cells (WBCs) and lymphocytes by up to 61% and 72%, respectively, in mice irradiated with protons at doses up to 2 Gy. The results also demonstrate that the dose rate, fractionation pattern and energy of the proton radiation did not have significant effects on WBC and lymphocyte counts in the irradiated animals. These results suggest that the acute effects of proton radiation on WBC and lymphocyte counts are determined mainly by the radiation dose, with very little contribution from the dose rate (over the range of dose rates evaluated), fractionation and energy of the protons.

Long-term results of exclusive low-dose rate curie-therapy for a high-grade vaginal intraepithelial neoplasia

International Nuclear Information System (INIS)

Blanchard, P.; Monnier, L.; Dumas, I.; Azoury, F.; Mazeron, R.; Haie-Meder, C.

2010-01-01

The authors report the results of an exclusive low dose rate curie therapy for female patients treated for a grade 3 vaginal intraepithelial neoplasia. They reviewed the medical files of patients treated since 1983, i.e. 28 women. They analysed demographic characteristics, the clinic description of lesions, possible treatments which occurred before this high-grade vaginal intraepithelial neoplasia, possible previous history of cervical or endometrial cancer, curie therapy detailed data, presence of tumorous relapse. According to that, they conclude that a 60 Gy exclusive low- vaginal dose-rate curie-therapy is an efficient and well tolerated treatment for high-grade vaginal intraepithelial neoplasia. Short communication

Endovascular Treatment Strategies in Aortoiliac Occlusion

International Nuclear Information System (INIS)

Ozkan, Ugur; Oguzkurt, Levent; Tercan, Fahri; Gumus, Burcak

2009-01-01

The aim of this study was to report our experience in endovascular treatment of total aortoiliac occlusion. Five patients who underwent endovascular recanalization procedures including manual aspiration thrombectomy, balloon angioplasty, and stent placement for total aortoiliac occlusion in a 4-year period were reviewed retrospectively. The mean age of patients was 51 years (range, 43 to 58 years). All patients had abdominal aorta and bilateral common iliac artery occlusion with or without external iliac artery occlusion. All patients either had a contraindication to surgery or refused it. Initial technical success was obtained in four of five (80%) patients. Endovascular techniques were successful in four patients who had good distal runoff and short-segment aortoiliac occlusion, but failed in a patient who had the worst distal runoff and long-segment aortoiliac occlusion. We observed two major complications, one of which was bilateral rupture of the common iliac arteries treated with covered stent placement. Another patient had extension of intra-aortic thrombus into the iliac stent after primary stenting. This was successfully treated with manual aspiration thrombectomy. Aortic and iliac stents remained patent during the follow-up period (median, 18 months; range, 3 to 26 months) in four patients. Primary patency rates at 6, 12, and 24 months were all 80%. In conclusion, endovascular treatment can be an alternative for aortoiliac occlusion in selected patients. Short- to midterm follow-up so far is satisfactory. Removal of intra-aortic thrombus with manual aspiration thrombectomy before balloon angioplasty and/or stenting is possible and a good alternative to thrombolysis.

Low-dose-rate high-let radiation cytogenetic effects on mice in vivo as model of space radiation action on mammalian

Science.gov (United States)

Sorokina, Svetlana; Zaichkina, Svetlana; Rozanova, Olga; Aptikaeva, Gella; Romanchenko, Sergei; Smirnova, Helene; Dyukina, Alsu; Peleshko, Vladimir

At present time little is known concerning the biological effects of low-dose-rate high-LET radiation exposure in space. The currently available experimental data on the biological effect of low doses of chronic radiation with high-LET values, which occur under the conditions of aircraft and space flights, have been primarily obtained in the examinations of pilots and astronauts after flights. Another way of obtaining this kind of evidence is the simulation of irradiation conditions during aircraft and space flights on high-energy accelerators and the conduction of large-scale experiments on animals under these conditions on Earth. In the present work, we investigated the cytogenetic effects of low-dose-rate high-LET radiation in the dose ranges of 0.2-30 cGy (1 cGy/day) and 0.5-16 cGy (0.43 cGy/day) in the radiation field behind the concrete shield of the Serpukhov accelerator of 70 GeV protons that simulates the spectral and component composition of radiation fields formed in the conditions of high-altitude flights on SHK mice in vivo. The dose dependence, adaptive response (AR) and the growth of solid tumor were examined. For induction of AR, two groups of mice were exposed to adapting doses of 0.2-30 cGy and the doses of 0.5-16 cGy of high-LET radiation. For comparison, third group of mice from unirradiated males was chronically irradiated with X-rays at adapting doses of 10 cGy (1 cGy/day). After a day, the mice of all groups were exposed to a challenging dose of 1.5 Gy of X-rays (1 Gy/min). After 28 h, the animals of all groups were killed by the method of cervical dislocation. Bone marrow specimens for calculating micronuclei (MN) in polychromatic erythrocytes (PCE) were prepared by a conventional method with minor modifications. The influence of adapting dose of 16 cGy on the growth of solid tumor of Ehrlich ascite carcinoma was estimated by measuring the size of the tumor at different times after the inoculation of ascitic cells s.c. into the femur. It was

Modulation of toxicity following external beam irradiation preceded by high-dose rate brachytherapy in inoperable oesophageal cancer

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Taal, B.G.; Aleman, B.M.P.; Koning, C.C.E.; Boot, H. [Nederlands Kanker Inst. `Antoni van Leeuwenhoekhuis`, Amsterdam (Netherlands)

1996-09-01

To induce fast relief of dysphagia in inoperable oesephageal cancer, we applied high-dose rate (HDR) intraluminal irradiation followed by external irradiation (EBRT) in a phase II study. 15 patients (group A: n = 15; 10 men, 5 women; median age 66 years) were treated with 10 Gy HDR brachytherapy plus 40 Gy EBRT (15 fractions of 2.67 Gy). Severe side-effects were encountered in 60% of patients: 3 late ulceration, 2 pending fistula and 2 patients with fatal haemorrhage after an interval of 6 months. Overall response was excellent: 9 complete remissions (60%) and 6 partial responses (40%). Because of the high toxicity rate, in a subsequent study (group B: n = 30; 23 mean, 7 women; median age 66 years) the EBRT scheme was changed using smaller fractions (2.0 Gy) to reach the same total dose of 40 Gy. The complication rate (17%) was significantly reduced, while the overall response remained excellent (83%): 17 complete and 8 partial responses. The impressive change in complication rate of HDR brachytherapy and EBRT stresses the impact of the fraction per dose and illustrates the small therapeutic margins. (author).

Modulation of toxicity following external beam irradiation preceded by high-dose rate brachytherapy in inoperable oesophageal cancer

International Nuclear Information System (INIS)

Taal, B.G.; Aleman, B.M.P.; Koning, C.C.E.; Boot, H.

1996-01-01

To induce fast relief of dysphagia in inoperable oesephageal cancer, we applied high-dose rate (HDR) intraluminal irradiation followed by external irradiation (EBRT) in a phase II study. 15 patients (group A: n = 15; 10 men, 5 women; median age 66 years) were treated with 10 Gy HDR brachytherapy plus 40 Gy EBRT (15 fractions of 2.67 Gy). Severe side-effects were encountered in 60% of patients: 3 late ulceration, 2 pending fistula and 2 patients with fatal haemorrhage after an interval of 6 months. Overall response was excellent: 9 complete remissions (60%) and 6 partial responses (40%). Because of the high toxicity rate, in a subsequent study (group B: n = 30; 23 mean, 7 women; median age 66 years) the EBRT scheme was changed using smaller fractions (2.0 Gy) to reach the same total dose of 40 Gy. The complication rate (17%) was significantly reduced, while the overall response remained excellent (83%): 17 complete and 8 partial responses. The impressive change in complication rate of HDR brachytherapy and EBRT stresses the impact of the fraction per dose and illustrates the small therapeutic margins. (author)

Nationwide, Multicenter, Retrospective Study on High-Dose-Rate Brachytherapy as Monotherapy for Prostate Cancer

International Nuclear Information System (INIS)

Yoshioka, Yasuo; Kotsuma, Tadayuki; Komiya, Akira; Kariya, Shinji; Konishi, Koji; Nonomura, Norio; Ogawa, Kazuhiko; Tanaka, Eiichi; Nishimura, Kensaku; Fujiuchi, Yasuyoshi; Kitamura, Hiroshi; Yamagami, Takuji; Yamasaki, Ichiro; Nishimura, Kazuo; Teshima, Teruki; Nakamura, Katsumasa; Itami, Jun

2017-01-01

Purpose: To present, analyze, and discuss results of a nationwide, multicenter, retrospective study on high-dose-rate brachytherapy (HDR-BT) as monotherapy for low-, intermediate-, and high-risk prostate cancer. Methods and Materials: From 1995 through 2013, 524 patients, 73 (14%) with low-risk, 207 (40%) with intermediate-risk, and 244 (47%) with high-risk prostate cancer, were treated with HDR-BT as monotherapy at 5 institutions in Japan. Dose fractionations were 27 Gy/2 fractions for 69 patients (13%), 45.5 Gy/7 fractions for 168 (32%), 49 Gy/7 fractions for 149 (28%), 54 Gy/9 fractions for 130 (25%), and others for 8 (2%). Of these patients, 156 (30%) did not receive androgen deprivation therapy, and 202 patients (39%) did receive androgen deprivation therapy 3 years. Median follow-up time was 5.9 years (range, 0.4-18.1 years), with a minimum of 2 years for surviving patients. Results: After 5 years, respective actuarial rates of no biochemical evidence of disease, overall survival, cause-specific survival, and metastasis-free survival for all patients were 92%, 97%, 99%, and 94%. For low/intermediate/high-risk patients, the 5-year no biochemical evidence of disease rates were 95%/94%/89%, the 5-year overall survival rates were 98%/98%/94%, the 5-year cause-specific survival rates were 98%/100%/98%, and the 5-year metastasis-free survival rates were 98%/95%/90%, respectively. The cumulative incidence of late grade 2 to 3 genitourinary toxicity at 5 years was 19%, and that of late grade 3 was 1%. The corresponding incidences of gastrointestinal toxicity were 3% and 0% (0.2%). No grade 4 or 5 of either type of toxicity was detected. Conclusions: The findings of this nationwide, multicenter, retrospective study demonstrate that HDR-BT as monotherapy was safe and effective for all patients with low-, intermediate-, and high-risk prostate cancer.

Nationwide, Multicenter, Retrospective Study on High-Dose-Rate Brachytherapy as Monotherapy for Prostate Cancer

Energy Technology Data Exchange (ETDEWEB)

Yoshioka, Yasuo, E-mail: yoshioka@radonc.med.osaka-u.ac.jp [Department of Radiation Oncology, Osaka University Graduate School of Medicine, Osaka (Japan); Kotsuma, Tadayuki [Department of Radiation Oncology, Osaka National Hospital, Osaka (Japan); Komiya, Akira [Department of Urology, Graduate School of Medicine and Pharmaceutical Sciences for Research, University of Toyama, Toyama (Japan); Department of Urology, Chiba University Hospital, Chiba (Japan); Kariya, Shinji [Department of Radiology, Kochi Medical School, Kochi (Japan); Konishi, Koji [Department of Radiation Oncology, Osaka Medical Center for Cancer and Cardiovascular Diseases, Osaka (Japan); Nonomura, Norio [Department of Urology, Osaka University Graduate School of Medicine, Osaka (Japan); Ogawa, Kazuhiko [Department of Radiation Oncology, Osaka University Graduate School of Medicine, Osaka (Japan); Tanaka, Eiichi [Department of Radiation Oncology, Osaka National Hospital, Osaka (Japan); Nishimura, Kensaku [Department of Urology, Osaka National Hospital, Osaka (Japan); Fujiuchi, Yasuyoshi; Kitamura, Hiroshi [Department of Urology, Graduate School of Medicine and Pharmaceutical Sciences for Research, University of Toyama, Toyama (Japan); Yamagami, Takuji [Department of Radiology, Kochi Medical School, Kochi (Japan); Yamasaki, Ichiro [Department of Urology, Kochi Medical School, Kochi (Japan); Nishimura, Kazuo [Department of Urology, Osaka Medical Center for Cancer and Cardiovascular Diseases, Osaka (Japan); Teshima, Teruki [Department of Radiation Oncology, Osaka Medical Center for Cancer and Cardiovascular Diseases, Osaka (Japan); Nakamura, Katsumasa [Department of Radiation Oncology, Hamamatsu University School of Medicine, Shizuoka (Japan); Itami, Jun [Department of Radiation Oncology, National Cancer Center Hospital, Tokyo (Japan)

2017-04-01

Purpose: To present, analyze, and discuss results of a nationwide, multicenter, retrospective study on high-dose-rate brachytherapy (HDR-BT) as monotherapy for low-, intermediate-, and high-risk prostate cancer. Methods and Materials: From 1995 through 2013, 524 patients, 73 (14%) with low-risk, 207 (40%) with intermediate-risk, and 244 (47%) with high-risk prostate cancer, were treated with HDR-BT as monotherapy at 5 institutions in Japan. Dose fractionations were 27 Gy/2 fractions for 69 patients (13%), 45.5 Gy/7 fractions for 168 (32%), 49 Gy/7 fractions for 149 (28%), 54 Gy/9 fractions for 130 (25%), and others for 8 (2%). Of these patients, 156 (30%) did not receive androgen deprivation therapy, and 202 patients (39%) did receive androgen deprivation therapy <1 year, 112 (21%) for 1-3 years, and 54 (10%) for >3 years. Median follow-up time was 5.9 years (range, 0.4-18.1 years), with a minimum of 2 years for surviving patients. Results: After 5 years, respective actuarial rates of no biochemical evidence of disease, overall survival, cause-specific survival, and metastasis-free survival for all patients were 92%, 97%, 99%, and 94%. For low/intermediate/high-risk patients, the 5-year no biochemical evidence of disease rates were 95%/94%/89%, the 5-year overall survival rates were 98%/98%/94%, the 5-year cause-specific survival rates were 98%/100%/98%, and the 5-year metastasis-free survival rates were 98%/95%/90%, respectively. The cumulative incidence of late grade 2 to 3 genitourinary toxicity at 5 years was 19%, and that of late grade 3 was 1%. The corresponding incidences of gastrointestinal toxicity were 3% and 0% (0.2%). No grade 4 or 5 of either type of toxicity was detected. Conclusions: The findings of this nationwide, multicenter, retrospective study demonstrate that HDR-BT as monotherapy was safe and effective for all patients with low-, intermediate-, and high-risk prostate cancer.

Scintillator performance at low dose rates and low temperatures for the CMS High Granularity Calorimeter for HL-LHC

CERN Document Server

Ricci-Tam, Francesca

2018-01-01

The High Luminosity LHC (HL-LHC) will integrate 10 times more luminosity than the LHC, posing significant challenges for radiation tolerance, especially for forward calorimetry, and highlights the issue for future colliders. As part of its HL-LHC upgrade program, the CMS collaboration is designing a High Granularity Calorimeter to replace the existing endcap calorimeters. The upgrade includes both electromagnetic and hadronic components, with the latter using a mixture of silicon sensors (in the highest radiation regions at high pseudorapidity) and scintillator as its active components. The scintillator will nevertheless receive large doses accumulated at low dose rates, and will have to operate at low temperature - around -30 degrees Celsius. We discuss measurements of scintillator radiation tolerance, from in-situ measurements from the current CMS endcap calorimeters, and from measurements at low temperature and low dose-rate at gamma sources in the laboratory.

Investigations on commercial semiconductor diodes as possible high dose rate radiation detectors

International Nuclear Information System (INIS)

Breitenhuber, L.; Kindl, P.; Obenaus, B.

1992-12-01

Investigations concerning the relevant properties of commercial semiconductor diodes such as their sensitivity and its dependence on accumulated dose, dose rate, energy, temperature and direction have been made in order to obtain their usefullness as radiation detectors. (authors)

The management of unimplantable stent during endovascular procedure:report of three cases

International Nuclear Information System (INIS)

Xiong Jiang; Wang Lijun; Guo Wei; Liu Xiaoping; Yin Tai; Jia Xin; Ma Xiaohui; Liu Meng; Zhang Hongpeng; Zhang Minhong

2010-01-01

Objective: To summarize the experience of dealing with the difficulty of the stent implantation encountered in the endovascular procedure. Methods: The causes of unimplantable stent encountered in the endovascular procedure included the delivery system entraping due to the stenosis and shrinking of peripheral self-expandable stent, the balloon expandable stent implantation and retrievement failure due to the rupture-balloon or stent edge opening, and the delivery system entraping due to aortic stent graft for aorta kinking. The balloon dilation for the stenosis and shrinking stent, the large caliber introducer sheath for removal of the rupture-balloon and edge opening, the expandable stent and balloon-assisted delivery system retrieve were used to solve the above three dilemma of unimplantable stent occurred in the endovascular procedure. Results: These three dilemma of stent unimplantable problem in the endovascular therapy were solved by endovascular method while little additional incision injury was added to the patients. Conclusion: For solving stent unimplantable problem the endovascular technique is the method of first choice, nevertherless, it is very important for the operator to be highly skilled in manipulating endovascular procedure. (authors)

Endovascular treatment of type B dissection in patients with Marfan syndrome: mid-term outcomes and aortic remodeling.

Science.gov (United States)

Eid-Lidt, Guering; Gaspar, Jorge; Meléndez-Ramírez, Gabriela; Cervantes S, Jorge; González-Pacheco, Hector; Dámas de Los Santos, Félix; Meave-González, Aloha; Ramírez Marroquín, Samuel

2013-12-01

To evaluate the mid-term outcomes, and the aortic remodeling in Marfan syndrome (MFS) patients with type B dissection that were treated with endovascular repair. MFS is a relative contraindication to thoracic endovascular aortic repair (TEVAR). Mid-term aortic outcomes data in MFS after TEVAR are limited, and the occurrence of late events remains unclear. Of 89 patients that underwent TEVAR between September 2002 and February 2011, 10 patients with mid-term follow-up fulfilled the Ghent criteria for MFS and complicated type B dissection. High risk for open surgery was documented in 90%. The mean age was 35.1 ± 9.4 years and all patients presented with acute aortic syndrome complicating a chronic type B dissection (DeBakey type IIIb). Five patients underwent a Bentall surgical procedure previous to endovascular repair, and in four patients initial TEVAR was followed by surgery of the ascending aorta. Treatment was limited to endovascular repair in only one patient. In-hospital mortality was 10%. At a mean follow-up of 59.6 ± 38.9 months, the cumulated mortality was of 20% and late mortality 11.1%. The rate of secondary endoleak was 44.4%, and late reintervention of 33.3%. Survival freedom from cardiovascular death at 8 years was 80.0%, and positive remodeling was documented in 37.5% of patients. Our results suggest that TEVAR is feasible, safe, and associated with a high reintervention rate and reduced rate of positive aortic remodeling in patients with Marfan syndrome. Survival at 8 years was comparable to contemporary series of open repair. Copyright © 2013 Wiley Periodicals, Inc.

The limiting dose rate and its importance in radiation protection

International Nuclear Information System (INIS)

Bakkiam, D.; Sonwani, Swetha; Arul Ananthakumar, A.; Mohankumar, Mary N.

2012-01-01

The concept of defining a low dose of ionizing radiation still remains unclear. Before attempting to define a low dose, it is more important to define a low-dose rate since effects at low dose-rates are different from those observed at higher dose-rates. Hence, it follows that low dose-rates rather than a low dose is an important criteria to determine radio-biological effects and risk factors i.e. stochastic health effects. Chromosomal aberrations induced by ionizing radiations are well fitted by quadratic model Y= áD + âD 2 + C with the linear coefficient of dose predominating for high LET radiations and low doses of low LET. At higher doses and dose rates of sparsely ionizing radiation, break pairs produced by inter-track action leads to the formation of exchange type aberrations and is dependent on dose rate. Whereas at lower doses and dose rates, intra-track action produces break pairs and resulting aberrations are in direct proportion to absorbed dose and independent of dose rate. The dose rate at which inter-track ceases to be observable and where intra-track action effectively becomes the sole contributor of lesion-pair formation is referred to as limiting dose rate (LDR). Once the LDR is reached further reduction in dose rates will not affect the slope of DR since breaks produced by independent charged particle tracks are widely separated in time to interact with each other for aberration yield. This linear dependency is also noticed for acute exposures at very low doses. Existing reports emphasizes the existence of LDR likely to be e6.3cGyh -1 . However no systematic studies have been conducted so far to determine LDR. In the present investigation DR curves were constructed for the dose rates 0.002 and 0.003 Gy/min and to define LDR at which a coefficient approaches zero. Extrapolation of limiting low dose rate data can be used to predict low dose effects regardless of dose rate and its definition ought to serve as a useful index for studies pertaining

High-dose-rate versus low-dose-rate brachytherapy in the treatment of cervical cancer: analysis of tumor recurrence - the University of Wisconsin experience

International Nuclear Information System (INIS)

Petereit, Daniel G.; Sarkaria, Jann N.; Potter, David M.; Schink, Julian C.

1999-01-01

Purpose: To retrospectively compare the clinical outcome for cervical cancer patients treated with high-dose-rate (HDR) vs. low-dose-rate (LDR) brachytherapy. Methods and Materials: One hundred ninety-one LDR patients were treated from 1977 to 1988 and compared to 173 HDR patients treated from 1989 to 1996. Patients of similar stage and tumor volumes were treated with identical external beam fractionation schedules. Brachytherapy was given in either 1 or 2 LDR implants for the earlier patient cohort, and 5 HDR implants for the latter cohort. For both patient groups, Point A received a minimum total dose of 80 Gy. The linear-quadratic formula was used to calculate the LDR dose-equivalent contribution to Point A for the HDR treatments. The primary endpoints assessed were survival, pelvic control, relapse-free survival, and distant metastases. Endpoints were estimated using the Kaplan-Meier method. Comparisons between treatment groups were performed using the log-rank test and Cox proportional hazards models. Results: The median follow-up was 65 months (2 to 208 months) in the LDR group and 22 months (1 to 85 months) in the HDR group. For all stages combined there was no difference in survival, pelvic control, relapse-free survival, or distant metastases between LDR and HDR patients. For Stage IB and II HDR patients, the pelvic control rates were 85% and 80% with survival rates of 86% and 65% at 3 years, respectively. In the LDR group, Stage IB and II patients had 91% and 78% pelvic control rates, with 82% and 58% survival rates at 3 years, respectively. No difference was seen in survival or pelvic control for bulky Stage I and II patients combined (> 5 cm). Pelvic control at 3 years was 44% (HDR) versus 75% (LDR) for Stage IIIB patients (p = 0.002). This difference in pelvic control was associated with a lower survival rate in the Stage IIIB HDR versus LDR population (33% versus 58%, p = 0.004). The only major difference, with regard to patient characteristics

Measurement of high dose rates of 60Co by gamma activation of115In and 111Cd foils

International Nuclear Information System (INIS)

Haddad, Kh; Qattan, M.; Taleb, A.

2009-12-01

The high gamma dose rate measurement technique using nuclear reaction (γ,(γ ' ') was introduced in this work. This technique is cheap, easy, reliable, and independent of chemical and physical factors, which affect other techniques. The response to the absorbed dose in this technique is linear and can be used for high dose. Cd and In foils were irradiated using 60 Co source and the resulted isomer activities were measured using gamma spectrometer. These foils were calibrated to be used as dosemeter and its results were compared with conventional one. The dose distribution in the irradiation field was determined using In foils. (authors)

Safety handling manual for high dose rate remote afterloading system

International Nuclear Information System (INIS)

1999-01-01

This manual is mainly for safety handling of 192 Ir-RALS (remote afterloading system) of high dose rate and followings were presented: Procedure and document format for the RALS therapy and for handling of its radiation source with the purpose of prevention of human errors and unexpected accidents, Procedure for preventing errors occurring in the treatment schedule and operation, and Procedure and format necessary for newly introducing the system into a facility. Consistency was intended in the description with the quality assurance guideline for therapy with small sealed radiation sources made by JASTRO (Japan Society for Therapeutic Radiology and Oncology). Use of the old type 60 Co-RALS was pointed out to be a serious problem remained and its safety handling procedure was also presented. (K.H.)

High-Dose-Rate Monotherapy: Safe and Effective Brachytherapy for Patients With Localized Prostate Cancer

International Nuclear Information System (INIS)

Demanes, D. Jeffrey; Martinez, Alvaro A.; Ghilezan, Michel; Hill, Dennis R.; Schour, Lionel; Brandt, David; Gustafson, Gary

2011-01-01

Purpose: High-dose-rate (HDR) brachytherapy used as the only treatment (monotherapy) for early prostate cancer is consistent with current concepts in prostate radiobiology, and the dose is reliably delivered in a prospectively defined anatomic distribution that meets all the requirements for safe and effective therapy. We report the disease control and toxicity of HDR monotherapy from California Endocurietherapy (CET) and William Beaumont Hospital (WBH) in low- and intermediate-risk prostate cancer patients. Methods and Materials: There were 298 patients with localized prostate cancer treated with HDR monotherapy between 1996 and 2005. Two biologically equivalent hypofractionation protocols were used. At CET the dose was 42 Gy in six fractions (two implantations 1 week apart) delivered to a computed tomography–defined planning treatment volume. At WBH the dose was 38 Gy in four fractions (one implantation) based on intraoperative transrectal ultrasound real-time treatment planning. The bladder, urethral, and rectal dose constraints were similar. Toxicity was scored with the National Cancer Institute Common Toxicity Criteria for Adverse Events version 3. Results: The median follow-up time was 5.2 years. The median age of the patients was 63 years, and the median value of the pretreatment prostate-specific antigen was 6.0 ng/mL. The 8-year results were 99% local control, 97% biochemical control (nadir +2), 99% distant metastasis–free survival, 99% cause-specific survival, and 95% overall survival. Toxicity was scored per event, meaning that an individual patient with more than one symptom was represented repeatedly in the morbidity data table. Genitourinary toxicity consisted of 10% transient Grade 2 urinary frequency or urgency and 3% Grade 3 episode of urinary retention. Gastrointestinal toxicity was <1%. Conclusions: High disease control rates and low morbidity demonstrate that HDR monotherapy is safe and effective for patients with localized prostate cancer.

High versus low dose-rate intracavitary irradiation for adenocarcinoma of the uterine cervix

International Nuclear Information System (INIS)

Kim, Woo Chul; Kim, Gwi Eon; Chung, Eun Ji; Suh, Chang Ok; Hong, Soon Won; Cho, Young Kap; Loh, John Jk

1999-01-01

The incidence of adenocarcinoma of the uterine cervix is low. Traditionally, Low Dose Rate (LDR) brachytherapy has been used as a standard modality in the treatment for patients with carcinoma of the uterine cervix. The purpose of this report is to evaluate the effects of the High Dose Rate (HDR) brachytherapy in the patients with adenocarcinoma of the uterine cervix compared with the LDR. From January 1971 to December 1992, 106 patients of adenocarcinoma of uterine cervix were treated with radiation therapy in the Department of Radiation Oncology, Yonsei University with curative intent. LDR brachytherapy was carried out on 35 patients and 71 patients were treated with HDR brachytherapy. In LDR Group, 8 patients were in stage I, 18 in stage II and 9 in stage III. external radiation therapy was delivered with 10 MV X-ray, daily 2 Gy fractionation, total dose 40-46 Gy (median 48 Gy). And LDR Radium intracavitary irradiation was performed with Henschke applicator, 22-56 Gy to point A (median 43 Gy). In HDR Group, there were 16 patients in stage I, 38 in stage II and 17 in stage III. The total dose of external radiation was 40-61 Gy (median 45 Gy), daily 1.8-2.0 Gy. HDR Co-60 intracavitary irradiation was performed with RALS(Remote Afterloading System), 30-57 Gy (median 39 Gy) to point A, 3 times a week, 3 Gy per fraction. The 5-year overall survival rate in LDR Group was 72.9%, 61.9%, 45.0% in stage I, II, III, respectively and corresponding figures for HDR were 87.1%, 58.3%, 41.2%, respectively (p>0.05). There was no statistical difference in terms of the 5-year overall survival rate between HDR Group and LDR Group in adenocarcinoma of the uterine cervix. There was 11% of late complication rates in LDR Group and 27% in HDR Group. There were no prognostic factors compared HDR with LDR group. The incidence of the late complication rate in HDR Group stage II, III was higher than that in LDR Group (16.7% vs. 31.6% in stage II, 11.1% vs. 35.3% in stage III, p>0

Brachytherapy optimization using radiobiological-based planning for high dose rate and permanent implants for prostate cancer treatment

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Seeley, Kaelyn; Cunha, J. Adam; Hong, Tae Min

2017-01-01

We discuss an improvement in brachytherapy--a prostate cancer treatment method that directly places radioactive seeds inside target cancerous regions--by optimizing the current standard for delivering dose. Currently, the seeds' spatiotemporal placement is determined by optimizing the dose based on a set of physical, user-defined constraints. One particular approach is the ``inverse planning'' algorithms that allow for tightly fit isodose lines around the target volumes in order to reduce dose to the patient's organs at risk. However, these dose distributions are typically computed assuming the same biological response to radiation for different types of tissues. In our work, we consider radiobiological parameters to account for the differences in the individual sensitivities and responses to radiation for tissues surrounding the target. Among the benefits are a more accurate toxicity rate and more coverage to target regions for planning high-dose-rate treatments as well as permanent implants.

Verification of the calculation program for brachytherapy planning system of high dose rate (PLATO)

International Nuclear Information System (INIS)

Almansa, J.; Alaman, C.; Perez-Alija, J.; Herrero, C.; Real, R. del; Ososrio, J. L.

2011-01-01

In our treatments are performed brachytherapy high dose rate since 2007. The procedures performed include gynecological intracavitary treatment and interstitial. The treatments are performed with a source of Ir-192 activity between 5 and 10 Ci such that small variations in treatment times can cause damage to the patient. In addition the Royal Decree 1566/1998 on Quality Criteria in radiotherapy establishes the need to verify the monitor units or treatment time in radiotherapy and brachytherapy. All this justifies the existence of a redundant system for brachytherapy dose calculation that can reveal any abnormality is present.

Impact of high- versus low-dose neuromuscular blocking agent administration on unplanned 30-day readmission rates in retroperitoneal laparoscopic surgery.

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Martijn Boon

Full Text Available Recent data shows that a neuromuscular block (NMB induced by administration of high doses of rocuronium improves surgical conditions in certain procedures. However, there are limited data on the effect such practices on postoperative outcomes. We performed a retrospective analysis to compare unplanned 30-day readmissions in patients that received high-dose versus low-dose rocuronium administration during general anesthesia for laparoscopic retroperitoneal surgery. This retrospective cohort study was performed in the Netherlands in an academic hospital where routine high-dose rocuronium NMB has been practiced since July 2015. Charts of patients receiving anesthesia between January 2014 and December 2016 were searched for surgical cases receiving high-dose rocuronium and matched with respect to procedure, age, sex and ASA classification to patients receiving low-dose rocuronium. The primary post-operative outcome was unplanned 30-day readmission rate. There were 130 patients in each cohort. Patients in the high- and low-dose rocuronium cohorts received 217 ± 49 versus 37 ± 5 mg rocuronium, respectively. In the high-dose rocuronium group neuromuscular activity was consistently monitored; matched patients were unreliably monitored. All patients receiving high-dose rocuronium were reversed with sugammadex, while just 33% of matched patients were reversed with sugammadex and 20% with neostigmine; the remaining patients were not reversed. Unplanned 30-day readmission rate was significantly lower in the high-dose compared to the low-dose rocuronium cohort (3.8% vs. 12.7%; p = 0.03; odds ratio = 0.33, 95% C.I. 0.12-0.95. This small retrospective study demonstrates a lower incidence of unplanned readmissions within 30-days following laparoscopic retroperitoneal surgery with high-dose relaxant anesthesia and sugammadex reversal in comparison to low-dose relaxant anesthesia. Further prospective studies are needed in larger samples to corroborate our

Impact of high- versus low-dose neuromuscular blocking agent administration on unplanned 30-day readmission rates in retroperitoneal laparoscopic surgery.

Science.gov (United States)

Boon, Martijn; Martini, Chris; Yang, H Keri; Sen, Shuvayu S; Bevers, Rob; Warlé, Michiel; Aarts, Leon; Niesters, Marieke; Dahan, Albert

2018-01-01

Recent data shows that a neuromuscular block (NMB) induced by administration of high doses of rocuronium improves surgical conditions in certain procedures. However, there are limited data on the effect such practices on postoperative outcomes. We performed a retrospective analysis to compare unplanned 30-day readmissions in patients that received high-dose versus low-dose rocuronium administration during general anesthesia for laparoscopic retroperitoneal surgery. This retrospective cohort study was performed in the Netherlands in an academic hospital where routine high-dose rocuronium NMB has been practiced since July 2015. Charts of patients receiving anesthesia between January 2014 and December 2016 were searched for surgical cases receiving high-dose rocuronium and matched with respect to procedure, age, sex and ASA classification to patients receiving low-dose rocuronium. The primary post-operative outcome was unplanned 30-day readmission rate. There were 130 patients in each cohort. Patients in the high- and low-dose rocuronium cohorts received 217 ± 49 versus 37 ± 5 mg rocuronium, respectively. In the high-dose rocuronium group neuromuscular activity was consistently monitored; matched patients were unreliably monitored. All patients receiving high-dose rocuronium were reversed with sugammadex, while just 33% of matched patients were reversed with sugammadex and 20% with neostigmine; the remaining patients were not reversed. Unplanned 30-day readmission rate was significantly lower in the high-dose compared to the low-dose rocuronium cohort (3.8% vs. 12.7%; p = 0.03; odds ratio = 0.33, 95% C.I. 0.12-0.95). This small retrospective study demonstrates a lower incidence of unplanned readmissions within 30-days following laparoscopic retroperitoneal surgery with high-dose relaxant anesthesia and sugammadex reversal in comparison to low-dose relaxant anesthesia. Further prospective studies are needed in larger samples to corroborate our findings and

Health effect of low dose/low dose rate radiation

International Nuclear Information System (INIS)

Kodama, Seiji

2012-01-01

The clarified and non-clarified scientific knowledge is discussed to consider the cause of confusion of explanation of the title subject. The low dose is defined roughly lower than 200 mGy and low dose rate, 0.05 mGy/min. The health effect is evaluated from 2 aspects of clinical symptom/radiation hazard protection. In the clinical aspect, the effect is classified in physical (early and late) and genetic ones, and is classified in stochastic (no threshold value, TV) and deterministic (with TV) ones from the radioprotection aspect. Although the absence of TV in the carcinogenic and genetic effects has not been proved, ICRP employs the stochastic standpoint from the safety aspect for radioprotection. The lowest human TV known now is 100 mGy, meaning that human deterministic effect would not be generated below this dose. Genetic deterministic effect can be observable only in animal experiments. These facts suggest that the practical risk of exposure to <100 mGy in human is the carcinogenesis. The relationship between carcinogenic risk in A-bomb survivors and their exposed dose are found fitted to the linear no TV model, but the epidemiologic data, because of restriction of subject number analyzed, do not always mean that the model is applicable even below the dose <100 mGy. This would be one of confusing causes in explanation: no carcinogenic risk at <100 mGy or risk linear to dose even at <100 mGy, neither of which is scientifically conclusive at present. Also mentioned is the scarce risk of cancer in residents living in the high background radiation regions in the world in comparison with that in the A-bomb survivors exposed to the chronic or acute low dose/dose rate. Molecular events are explained for the low-dose radiation-induced DNA damage and its repair, gene mutation and chromosome aberration, hypothesis of carcinogenesis by mutation, and non-targeting effect of radiation (bystander effect and gene instability). Further researches to elucidate the low dose

Results of radiation therapy for uterine cervical cancer using high dose rate remote after loading system

International Nuclear Information System (INIS)

Ogawa, Yoshihiro; Nemoto, Kenji

2003-01-01

In Japan, radiotherapy with high dose rate remote after loading system (HDR-RALS) for intracavitary brachytherapy is the standard treatment for more than 30 years. This report showed the usefulness of HDR-RALS for uterine cervical cancer. From 1980 through 1999, 442 patients with uterine cervical cancers (stage I: 66, stage II: 161, stage III: 165, stage IV: 50) were treated. Radiotherapy was performed both external teletherapy and HDR-RALS. Overall survival rate at 5 years was 60.2%. The 5-year actuarial incidence of all complications was 16.4%. The 5-year actuarial incidence of all complications in cases treated with the sum doses of whole pelvic irradiation (without central shield) and RALS up to 49 Gy, 50 to 59 Gy or larger doses were 7.5%, 11.0% and 25.2%, respectively. Radiation therapy using HDR-RALS was very effective. While the dose of whole pelvic irradiation was increased, the actuarial incidence of all complications was increased. (author)

Comparison of Total Arch and Partial Arch Transposition During Hybrid Endovascular Repair for Aortic Arch Disease.

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Kang, W C; Ko, Y-G; Oh, P C; Shin, E K; Park, C-H; Choi, D; Youn, Y N; Lee, D Y

2016-08-01

Total arch transposition (TAT) during hybrid endovascular repair for aortic arch disease is believed to allow a better landing zone, but also to be associated with higher peri-operative mortality than partial arch transposition (PAT). Information on this issue is limited. This study was a retrospective analysis. All 53 consecutive patients with aortic arch disease (41 males, mean age 65.0 years) who underwent hybrid endovascular repair with TAT (zone 0, n=20) or PAT (zone 1 or 2, n=33) from 2008 to 2014 were analyzed retrospectively. The peri-operative and late outcomes of these two groups were compared. Baseline characteristics, including EuroSCORE II results, were similar in the two groups. After procedures, peri-operative mortalities and stroke rates were similar in the two groups (5.0% vs. 9.1%, p=1.000, and 10.0% vs. 6.1%, p=.627). Interestingly, all four strokes occurred in patients with a type III aortic arch irrespective of transposition type. Primary success rates (80.0% vs. 69.7%, p=.527) and type I endoleak incidences (20.0% vs. 27.3%, p=.744) were not significantly different. During follow up (mean duration 36.9 months), overall survival (89.7% vs. 87.4% at 1 year and 89.7% vs. 79.3% at 3 years; p=.375) and re-intervention free survival rates (78.6% vs. 92.0% at 1 year; 72.0% vs. 62.2% at 3 years, p=.872) were similar in the two groups. Morbidity and mortality were high within the first year of hybrid endovascular therapy for aortic arch disease, implying that candidates for hybrid procedures need to be selected carefully. Hybrid endovascular repair with TAT was found to have peri-operative mortality, stroke, and long-term survival rates comparable with PAT, so hybrid endovascular repair may be considered, irrespective of type of arch reconstruction, when clinically indicated. Copyright © 2016 European Society for Vascular Surgery. Published by Elsevier Ltd. All rights reserved.

Treatment of Recurrent Bronchial Carcinoma: The Role of High-Dose-Rate Endoluminal Brachytherapy

International Nuclear Information System (INIS)

Hauswald, Henrik; Stoiber, Eva; Rochet, Nathalie; Lindel, Katja; Grehn, Christian; Becker, Heinrich D.; Debus, Juergen; Harms, Wolfgang

2010-01-01

Purpose: This study's aim was to assess outcome and toxicity of high-dose-rate endoluminal brachytherapy (HDREB) for recurrent bronchial carcinoma. Methods and Materials: From 1987 to 2005, 41 patients were treated with HDREB for symptomatic recurrent bronchial carcinoma. All patients had previously undergone external beam radiotherapy (EBRT) with a median dose of 56 Gy (range, 30-70 Gy). The median HDREB dose applied was 15 Gy (range, 5-29 Gy). The median time interval between primary EBRT and reirradiation was 9 months (range, 2-54 months). Results: After a median follow-up of 6.7 months, the 6-, 12-, and 24-month overall survival rates were 58%, 18%, and 7%, respectively. The median overall survival time was 6.7 months. Local remission was achieved in 73% of patients (n = 30). A total of 24% of patients (n = 10) showed no response or progressive disease within 8 weeks after treatment. In 1 patient, treatment response was not documented. The 6-, 12-, and 24-month local control rates were 38%, 17%, and 3%, respectively. The median local progression-free survival time was 4 months (range, 1-23 months). Prognostic factors were a total dose of ≥15 Gy of HDREB (p = 0.029) and a Karnofsky performance score of ≥80% (p = 0.0012). The cause of death was locoregional progression in 27% of patients (n = 11), distant metastases in 24% of patients (n = 10), fatal hemorrhage in 15% of patients (n = 6), and other causes in 29% of patients (n = 12). None of the patients with locally controlled disease showed grade 3 or 4 late effects. Conclusions: Palliative treatment of symptomatic, locally recurrent bronchial carcinoma with HDREB can effectively relieve symptoms in the majority of patients while causing only few complications. Still, time to progression is short.

Endovascular aneurysm repair (EVAR) follow-up imaging: the assessment and treatment of common postoperative complications

International Nuclear Information System (INIS)

Ilyas, S.; Shaida, N.; Thakor, A.S.; Winterbottom, A.; Cousins, C.

2015-01-01

Endovascular abdominal aortic aneurysm repair (EVAR) is a well-established procedure, which has long-term mortality rates similar to that of open repair. It has the additional benefit of being less invasive, making it the favoured method of treating abdominal aortic aneurysms in elderly and high-risk patients with multiple co-morbidities. The main disadvantage of EVAR is the higher rate of re-intervention, due to device-related complications, including endoleaks, limb occlusion, stent migration, kinking, and infection. As a result lifelong surveillance is required. In order to avoid missing these complications, intricate knowledge of stent graft design, good-quality diagnostic ultrasound skills, multiplanar reformatting of CT images, and reproducible investigations are important. Most of these complications can be treated via an endovascular approach using cuff extensions, uncovered stents, coils, and liquid embolic agents. Open surgery is reserved for complex complications, where an endovascular approach is not feasible. - Highlights: • Comprehensive pictorial review of EVAR related complications. • Importance of life-long EVAR surveillance, to prevent aortic rupture or lower limb ischaemia. • Identification and management of endoleaks, rupture, migration, kink/infolding, occlusion and infection

Predictors of Reintervention After Endovascular Repair of Isolated Iliac Artery Aneurysm

International Nuclear Information System (INIS)

Zayed, Hany A.; Attia, Rizwan; Modarai, Bijan; Clough, Rachel E.; Bell, Rachel E.; Carrell, Tom; Sabharwal, Tarun; Reidy, John; Taylor, Peter R.

2011-01-01

The objective of this study was to identify factors predicting the need for reintervention after endovascular repair of isolated iliac artery aneurysm (IIAA). We reviewed prospectively collected database records of all patients who underwent endovascular repair of IIAA between 1999 and 2008. Detailed assessment of the aneurysms was performed using computed tomography angiography (CTA). Follow-up protocol included CTA at 3 months. If this showed no complication, then annual duplex scan was arranged. Multivariate analysis and analysis of patient survival and freedom from reintervention were performed using Kaplan–Meier life tables. Forty IIAAs (median diameter 44 mm) in 38 patients were treated (all men; median age 75 years), and median follow-up was 27 months. Endovascular repair of IIAA was required in 14 of 40 aneurysms (35%). The rate of type I endoleak was significantly higher with proximal landing zone (PLZ) diameter >30 mm in the aorta or >24 mm in the common iliac artery or distal landing zone (DLZ) diameter >24 mm (P = 0.03, 0.03, and 0.0014, respectively). Reintervention rate (RR) increased significantly with increased diameter or decreased length of PLZ; increased DLZ diameter; and endovascular IIAA repair (P = 0.005, 0.005, 0.02, and 0.02 respectively); however, RR was not significantly affected by length of PLZ or DLZ. Freedom-from-reintervention was 97, 93, and 86% at 12, 24, and 108 months. There was no in-hospital or aneurysm-related mortality. Endovascular IIAA repair is a safe treatment option. Proper patient selection is essential to decrease the RR.

γ-ray dose rate effect in DNA double-strand break repair deficient murine cells

International Nuclear Information System (INIS)

Li Liya; Li Peiwen

2002-01-01

Objective: To analyze the dose rate effect and potentially lethal damage repair in DNA double-strand break repair deficient murine cells (SCID) irradiated by γ-ray. Methods: The wild type (CB.17+/+) and SCID cells were exposed to γ-ray at high and low dose rates. The high dose rate exposure was fractionated into two equal doses at 24 h intervals. The survival rates of irradiated cells were calculated by clone-forming analysis. Results: When γ-ray was given to wild type (CB.17+/+) cells in two fractions at 24 h intervals, the survival rate was significantly higher than that when the same total dose was given singly. In contrast, there was no difference in the survival rates between the single and fractionated exposure in SCID cells. SCID cells were more sensitive than CB.17+/+ cells to both low and high dose rates γ-ray exposure for cell killing. The survival rate by low dose rate exposure was significantly higher than that by high dose rate exposure, not only in CB.17+/+ cells but also in SCID cells. Conclusions: SCID cells are deficient in repairing γ-ray induced double-strand breaks. There is dose rate effect in both SCID and CB.17+/+ cells

High versus low dose rate intracavitary irradiation for adenocarcinoma of the uterine cervix

International Nuclear Information System (INIS)

Kim, Woo-Chul; Loh, John J.K.; Kim, Gwi-Eon; Suh, Chang-Ok

2001-01-01

Traditionally, low dose rate (LDR) brachytherapy has been used as a standard modality in the treatment of patients with carcinoma of the uterine cervix. The purpose of this work was to evaluate the effects of high dose rate (HDR) brachytherapy on patients with adenocarcinoma of the uterine cervix and to compare them with the effects of LDR brachytherapy. From January 1971 to December 1992, 104 patients suffering from adenocarcinoma of the uterine cervix were treated with radiation therapy in the Department of Radiation Oncology, Yonsei University. LDR brachytherapy was carried out on 34 patients and HDR brachytherapy on 70 patients. In the LDR group, eight patients were in stage IB, six in IIA, 12 in IIB, three in IIIA and five in IIIB. External radiation therapy was delivered with 10 MV X-rays, 2 Gy fraction per day, total dose of whole pelvis 36-52 Gy (median 46 Gy). LDR radium intracavitary irradiation was performed with a Henschke applicator, 37-59 Gy targeted at point A (median 43 Gy). In the HDR group, there were 16 patients in stage IB, six in IIA, 32 in IIB and 16 in IIIB. The total whole pelvis dose of external radiation was 40-50 Gy (median 44 Gy), daily 1.8-2.0 Gy. HDR Co-60 intracavitary irradiation was performed with a remotely controlled after-loading system (RALS), 30-48 Gy (median 39 Gy) targeted at point A, three times per week, 3 Gy per fraction. The 5-year overall survival rate in the LDR group was 72.9, 61.9 and 35.7% in stage I, II and III, respectively and the corresponding figures for HDR were 87.1, 58.3 and 43.8% (p 0.05). No prognostic factors were evident in the comparison between the two groups. There was no difference in terms of 5-year survival rate in the patients with adenocarcinoma of the uterine cervix between those treated with HDR and those treated with LDR brachytherapy. Even though late complication rates were higher in the HDR group, most of them were classified as grade I. This retrospective study suggests that HDR

Conversion Factors for Predicting Unshielded Dose Rates in Shielded Waste

International Nuclear Information System (INIS)

Clapham, M.; Seamans Jr, J.V.; Arbon, R.E.

2009-01-01

This document describes the methodology developed and used by the Advanced Mixed Waste Treatment Project for determining the activity content and the unshielded surface dose rate for lead lined containers contaminated with transuranic waste. Several methods were investigated: - Direct measurement of the dose rate after removing the shielding. - Use of a MicroShield R derived dose conversion factor, (mRem/hr unshielded )/(mRem/hr shielded ), applied to the measured surface dose rate to estimate the unshielded surface dose rate. - Use of a MicroShield R derived activity conversion factor, mRem/hr unshielded /Ci, applied to the measured activity to estimate the unshielded dose rate. - Use of an empirically derived activity conversion factor, mRem/hr unshielded /Ci, applied to the measured activity to estimate the unshielded dose rate. The last approach proved to be the most efficacious by using a combination of nondestructive assay and empirically defined dose rate conversion factors. Empirically derived conversion factors were found to be highly dependent upon the matrix of the waste. Use of conversion factors relied on activity values corrected to address the presence of a lead liner. (authors)

Postoperative vaginal irradiation by a high dose-rate afterloading technique in endometrial carcinoma stage I

International Nuclear Information System (INIS)

Sorbe, B.; Smeds, A.C.

1989-01-01

A high dose-rate (cobalt-60) afterloading technique was used for postoperative vaginal irradiation in a series of 404 women with endometrial carcinoma stage I. The total recurrence rate was 3.7% with 0.7% vaginal lesions. The crude 5-year survival rate for the complete series was 91.8% compared to 13.3% for those with recurrences. Depth of myometrical infiltration (>1/3 of the uterine wall) and nuclear grade were the most important prognostic factors. Clinically significant late radiation reactions (bladder and/or rectum) were recorded in 6.9%. The absorbed dose per fraction and the size of the treatment volume were significantly related to the occurrence of both early and late radiation reactions. Vaginal shortening was closely related to the dose per fraction, length of the referce isodose and the applicator diameter. The shape of the vaginal applicator versus the isodose contours and the importance of the source train geometry and relative activity for absorbed dose inhomogeneitis within the treatment volume are discussed. Cumulative radiation effect (CRE) and linear-quadratic (LQ) calculations have been performed and related to tissue reactions within the target volume and in the risk organs. An alpha-beta quotient of 8.8 Gy for vaginal shrinkage effect and 2.0 Gy for late rectal complications are suggested on the basis of calculations using a maximum likelihood method for quantal radiation data. (orig.)

Endovascular treatment of penetrating arterial trauma with stent grafts.

Science.gov (United States)

Biagioni, Rodrigo Bruno; Burihan, Marcelo Calil; Nasser, Felipe; Biagioni, Luisa Ciucci; Ingrund, José Carlos

2018-02-01

The endovascular management of arterial injuries has resulted in reduced operating time, blood loss, hospital mortality, lower incidence of sepsis, and decrease in mortality rates. For penetrating trauma, however, the benefits of endovascular therapy are questionable. Data were obtained by retrospective analysis of electronic medical records. All patients with vascular trauma seeking care at our institution from January 2010 to December 2015 were reviewed. A total of 223 vascular trauma patients were enrolled. Of these, 18 patients (8 %) were treated with endovascular techniques. The data related to clinical presentation, patient characteristics, technical aspects of the treatment, and follow-up were analysed. The mean patient age was 35.4 ± 17.8 years, 94 % were male. The mean injury severity score was 10.4 ± 2.5. The most commonly observed trauma mechanism was a gunshot in 10 cases (55 %), followed by lesions provoked by arterial catheter misplacement in five cases (27 %), and stab wounds in three cases (16.6 %). The main injury site was the subclavian artery, accounting for eight cases (44 %), followed by the superficial femoral artery and the tibiofibular trunk in two cases, respectively (18 %). The anterior tibial, fibular artery, axillary, common carotid, superior mesenteric, and profunda femoris were each affected once. Arteriovenous fistula was detected in nine cases (50 %), pseudoaneurysms in nine cases (50 %), and short occlusion in two cases (11 %). The mean follow-up duration was 753 days. The primary patency rate was 92.3 and 61.5 % after one and two years, respectively. The survival rate was 94.4 % after one and two years. Infection of the stents or limb amputations were not identified at follow-up. The endovascular treatment of penetrating arterial injuries with covered stents is feasible. However, the criteria used to choose the best method must be individualized.

Dose rate measuring device and dose rate measuring method using the same

International Nuclear Information System (INIS)

Urata, Megumu; Matsushita, Takashi; Hanazawa, Sadao; Konno, Takahiro; Chiba, Yoshinori; Yumitate, Tadahiro

1998-01-01

The device of the present invention comprises a scintillation fiber scope having a shape elongated in the direction of the height of a pressure vessel and emitting light by incident of radiation to detect radiation, a radioactivity measuring device for measuring a dose rate based on the detection of the fiber scope and a reel means for dispensing and taking up the fiber scope, and it constituted such that the dose rate of the pressure vessel and that of a shroud are determined independently. Then, when the taken out shroud is contained in an container, excessive shielding is not necessary, in addition, this device can reliably be inserted to or withdrawn from complicated places between the pressure vessel and the shroud, and further, the dose rate of the pressure vessel and that of the shroud can be measured approximately accurately even when the thickness of them is different greatly. (N.H.)

Dose rate measuring device and dose rate measuring method using the same

Energy Technology Data Exchange (ETDEWEB)

Urata, Megumu; Matsushita, Takashi; Hanazawa, Sadao; Konno, Takahiro; Chiba, Yoshinori; Yumitate, Tadahiro

1998-11-13

The device of the present invention comprises a scintillation fiber scope having a shape elongated in the direction of the height of a pressure vessel and emitting light by incident of radiation to detect radiation, a radioactivity measuring device for measuring a dose rate based on the detection of the fiber scope and a reel means for dispensing and taking up the fiber scope, and it constituted such that the dose rate of the pressure vessel and that of a shroud are determined independently. Then, when the taken out shroud is contained in an container, excessive shielding is not necessary, in addition, this device can reliably be inserted to or withdrawn from complicated places between the pressure vessel and the shroud, and further, the dose rate of the pressure vessel and that of the shroud can be measured approximately accurately even when the thickness of them is different greatly. (N.H.)

Dose rate and fractionation: Relative importance in radiation for bone marrow transplantation

International Nuclear Information System (INIS)

Tarbell, N.J.; Rosenblatt, M.; Mauch, P.; Hellman, S.

1987-01-01

The optimal dose rate and fractionation schedules for total body irradiation (TBI) in bone marrow transplantation (BMT) are presently unknown. This study compares several fractionation and dose rate schedules that are currently in clinical use. C/sub 3/H/HeJ were given TBI and the bone marrow survival fraction was calculated using the CFU's assay. Irradiation was given as low dose rate (LDR) at 5 cGy/min or high dose rate (HDR) at 80 cGy/min, in single fraction (SF) and fractionated (FX) regimens. These results indicate no increase in survival for the normal bone marrow stem cells with fractionation either at high or low dose-rates. In fact, fractionation seemed to decrease the bone marrow survival over single fraction radiation

Rectal Bleeding After High-Dose-Rate Brachytherapy Combined With Hypofractionated External-Beam Radiotherapy for Localized Prostate Cancer: The Relationship Between Dose-Volume Histogram Parameters and the Occurrence Rate

International Nuclear Information System (INIS)

Okamoto, Masahiko; Ishikawa, Hitoshi; Ebara, Takeshi; Kato, Hiroyuki; Tamaki, Tomoaki; Akimoto, Tetsuo; Ito, Kazuto; Miyakubo, Mai; Yamamoto, Takumi; Suzuki, Kazuhiro; Takahashi, Takeo; Nakano, Takashi

2012-01-01

Purpose: To determine the predictive risk factors for Grade 2 or worse rectal bleeding after high-dose-rate brachytherapy (HDR-BT) combined with hypofractionated external-beam radiotherapy (EBRT) for prostate cancer using dose–volume histogram analysis. Methods and Materials: The records of 216 patients treated with HDR-BT combined with EBRT were analyzed. The treatment protocols for HDR-BT were 5 Gy × five times in 3 days or 7 Gy × three, 10.5 Gy × two, or 9 Gy × two in 2 days. The EBRT doses ranged from 45 to 51 Gy with a fractional dose of 3 Gy. Results: In 20 patients Grade 2 or worse rectal bleeding developed, and the cumulative incidence rate was 9% at 5 years. By converting the HDR-BT and EBRT radiation doses into biologic effective doses (BED), the BED 3 at rectal volumes of 5% and 10% in the patients who experienced bleeding were significantly higher than those in the remaining 196 patients. Univariate analysis showed that a higher rectal BED 3–5% and the use of fewer needles in brachytherapy were correlated with the incidence of bleeding, but BED 3–5% was found to be the only significant factor on multivariate analysis. Conclusions: The radiation dose delivered to small rectal lesions as 5% is important for predicting Grade 2 or worse rectal bleeding after HDR-BT combined with EBRT for prostate cancer.

Dose and dose rate effects of whole-body gamma-irradiation: II. Hematological variables and cytokines

Science.gov (United States)

Gridley, D. S.; Pecaut, M. J.; Miller, G. M.; Moyers, M. F.; Nelson, G. A.

2001-01-01

The goal of part II of this study was to evaluate the effects of gamma-radiation on circulating blood cells, functional characteristics of splenocytes, and cytokine expression after whole-body irradiation at varying total doses and at low- and high-dose-rates (LDR, HDR). Young adult C57BL/6 mice (n = 75) were irradiated with either 1 cGy/min or 80 cGy/min photons from a 60Co source to cumulative doses of 0.5, 1.5, and 3.0 Gy. The animals were euthanized at 4 days post-exposure for in vitro assays. Significant dose- (but not dose-rate-) dependent decreases were observed in erythrocyte and blood leukocyte counts, hemoglobin, hematocrit, lipopolysaccharide (LPS)-induced 3H-thymidine incorporation, and interleukin-2 (IL-2) secretion by activated spleen cells when compared to sham-irradiated controls (p < 0.05). Basal proliferation of leukocytes in the blood and spleen increased significantly with increasing dose (p < 0.05). Significant dose rate effects were observed only in thrombocyte counts. Plasma levels of transforming growth factor-beta 1 (TGF-beta 1) and splenocyte secretion of tumor necrosis factor-alpha (TNF-alpha) were not affected by either the dose or dose rate of radiation. The data demonstrate that the responses of blood and spleen were largely dependent upon the total dose of radiation employed and that an 80-fold difference in the dose rate was not a significant factor in the great majority of measurements.

Visuospatial and psychomotor aptitude predicts endovascular performance of inexperienced individuals on a virtual reality simulator.

Science.gov (United States)

Van Herzeele, Isabelle; O'Donoghue, Kevin G L; Aggarwal, Rajesh; Vermassen, Frank; Darzi, Ara; Cheshire, Nicholas J W

2010-04-01

This study evaluated virtual reality (VR) simulation for endovascular training of medical students to determine whether innate perceptual, visuospatial, and psychomotor aptitude (VSA) can predict initial and plateau phase of technical endovascular skills acquisition. Twenty medical students received didactic and endovascular training on a commercially available VR simulator. Each student treated a series of 10 identical noncomplex renal artery stenoses endovascularly. The simulator recorded performance data instantly and objectively. An experienced interventionalist rated the performance at the initial and final sessions using generic (out of 40) and procedure-specific (out of 30) rating scales. VSA were tested with fine motor dexterity (FMD, Perdue Pegboard), psychomotor ability (minimally invasive virtual reality surgical trainer [MIST-VR]), image recall (Rey-Osterrieth), and organizational aptitude (map-planning). VSA performance scores were correlated with the assessment parameters of endovascular skills at commencement and completion of training. Medical students exhibited statistically significant learning curves from the initial to the plateau performance for contrast usage (medians, 28 vs 17 mL, P dexterity as well as with image recall at end of the training period. In addition to current recruitment strategies, VSA may be a useful tool for predictive validity studies.

High-dose-rate brachytherapy using molds for oral cavity cancer. The technique and its limitations

International Nuclear Information System (INIS)

Nishimura, Yasumasa; Yokoe, Yoshihiko; Nagata, Yasushi; Okajima, Kaoru; Nishida, Mitsuo; Hiraoka, Masahiro

1998-01-01

With the availability of a high-dose-rate (HDR) remote afterloading device, a Phase I/II protocol was initiated at our institution to assess the toxicity and efficacy of HDR intracavitary brachytherapy, using molds, in the treatment of squamous cell carcinomas of the oral cavity. Eight patients with squamous cell carcinoma of the oral cavity were treated by the technique. The primary sites of the tumors were the buccal mucosa, oral floor, and gingiva. Two of the buccal mucosal cancers were located in the retromolar trigon. For each patient, a customized mold was fabricated, in which two to four afterloading catheters were placed for an 192 Ir HDR source. Four to seven fractions of 3-4 Gy, 5 mm below the mold surface, were given following external radiation therapy of 40-60 Gy/ 2 Gy. The total dose of HDR brachytherapy ranged from 16 to 28Gy. Although a good initial complete response rate of 7/8 (88%) was achieved, there was local recurrence in four of these seven patients. Both of the retromolar trigon tumors showed marginal recurrence. No serious (e.g., ulcer or bone exposure) late radiation damage has been observed thus far in the follow up period of 15-57 months. High-dose-rate brachytherapy using the mold technique seems a safe and useful method for selected early and superficial oral cavity cancer. However, it is not indicated for thick tumors and/or tumors located in the retromolar trigon. (author)

Investigations of DNA damage induction and repair resulting from cellular exposure to high dose-rate pulsed proton beams

International Nuclear Information System (INIS)

Renis, M.; Malfa, G.; Tomasello, B.; Borghesi, M.; Schettino, G.; Favetta, M.; Romano, F.; Cirrone, G. A. P.; Manti, L.

2013-01-01

Studies regarding the radiobiological effects of low dose radiation, microbeam irradiation services have been developed in the world and today laser acceleration of protons and heavy ions may be used in radiation therapy. The application of different facilities is essential for studying bystander effects and relating signalling phenomena in different cells or tissues. In particular the use of ion beams results advantageous in cancer radiotherapy compared to more commonly used X-rays, since the ability of ions in delivering lethal amount of doses into the target tumour avoiding or limiting damage to the contiguous healthy tissues. At the INFN-LNS in Catania, a multidisciplinary radiobiology group is strategically structured aimed to develop radiobiological research, finalised to therapeutic applications, compatible with the use of high dose laser-driven ion beams. The characteristic non-continuous dose rates with several orders of magnitude of laser-driven ion beams makes this facility very interesting in the cellular systems' response to ultra-high dose rates with non-conventional pulse time intervals cellular studies. Our group have projected to examine the effect of high dose laser-driven ion beams on two cellular types: foetal fibroblasts (normal control cells) and DU145 (prostate cancer cells), studying the modulation of some different bio-molecular parameters, in particular cell proliferation and viability, DNA damage, redox cellular status, morphological alterations of both the cytoskeleton components and some cell organelles and the possible presence of apoptotic or necrotic cell death. Our group performed preliminary experiments with high energy (60 MeV), dose rate of 10 Gy/min, doses of 1, 2, 3 Gy and LET 1 keV/μm on human foetal fibroblasts (control cells). We observed that cell viability was not influenced by the characteristics of the beam, the irradiation conditions or the analysis time. Conversely, DNA damage was present at time 0, immediately

Investigations of DNA damage induction and repair resulting from cellular exposure to high dose-rate pulsed proton beams

Energy Technology Data Exchange (ETDEWEB)

Renis, M.; Malfa, G.; Tomasello, B. [Drug Sciences Department, University of Catania, Catania (Italy); Borghesi, M.; Schettino, G. [Queen' s University Belfast, Northern Ireland (United Kingdom); Favetta, M.; Romano, F.; Cirrone, G. A. P. [National Institute for Nuclear Physics (INFN-LNS), Catania (Italy); Manti, L. [Physics Science Department, University of Naples Federico II, Naples, and National Institute for Nuclear Physics (INFN), Naples (Italy)

2013-07-26

Studies regarding the radiobiological effects of low dose radiation, microbeam irradiation services have been developed in the world and today laser acceleration of protons and heavy ions may be used in radiation therapy. The application of different facilities is essential for studying bystander effects and relating signalling phenomena in different cells or tissues. In particular the use of ion beams results advantageous in cancer radiotherapy compared to more commonly used X-rays, since the ability of ions in delivering lethal amount of doses into the target tumour avoiding or limiting damage to the contiguous healthy tissues. At the INFN-LNS in Catania, a multidisciplinary radiobiology group is strategically structured aimed to develop radiobiological research, finalised to therapeutic applications, compatible with the use of high dose laser-driven ion beams. The characteristic non-continuous dose rates with several orders of magnitude of laser-driven ion beams makes this facility very interesting in the cellular systems' response to ultra-high dose rates with non-conventional pulse time intervals cellular studies. Our group have projected to examine the effect of high dose laser-driven ion beams on two cellular types: foetal fibroblasts (normal control cells) and DU145 (prostate cancer cells), studying the modulation of some different bio-molecular parameters, in particular cell proliferation and viability, DNA damage, redox cellular status, morphological alterations of both the cytoskeleton components and some cell organelles and the possible presence of apoptotic or necrotic cell death. Our group performed preliminary experiments with high energy (60 MeV), dose rate of 10 Gy/min, doses of 1, 2, 3 Gy and LET 1 keV/μm on human foetal fibroblasts (control cells). We observed that cell viability was not influenced by the characteristics of the beam, the irradiation conditions or the analysis time. Conversely, DNA damage was present at time 0, immediately

Dosimetric perturbations of a lead shield for surface and interstitial high-dose-rate brachytherapy

International Nuclear Information System (INIS)

Candela-Juan, Cristian; Granero, Domingo; Vijande, Javier; Ballester, Facundo; Perez-Calatayud, Jose; Rivard, Mark J

2014-01-01

In surface and interstitial high-dose-rate brachytherapy with either 60 Co, 192 Ir, or 169 Yb sources, some radiosensitive organs near the surface may be exposed to high absorbed doses. This may be reduced by covering the implants with a lead shield on the body surface, which results in dosimetric perturbations. Monte Carlo simulations in Geant4 were performed for the three radionuclides placed at a single dwell position. Four different shield thicknesses (0, 3, 6, and 10 mm) and three different source depths (0, 5, and 10 mm) in water were considered, with the lead shield placed at the phantom surface. Backscatter dose enhancement and transmission data were obtained for the lead shields. Results were corrected to account for a realistic clinical case with multiple dwell positions. The range of the high backscatter dose enhancement in water is 3 mm for 60 Co and 1 mm for both 192 Ir and 169 Yb. Transmission data for 60 Co and 192 Ir are smaller than those reported by Papagiannis et al (2008 Med. Phys. 35 4898–4906) for brachytherapy facility shielding; for 169 Yb, the difference is negligible. In conclusion, the backscatter overdose produced by the lead shield can be avoided by just adding a few millimetres of bolus. Transmission data provided in this work as a function of lead thickness can be used to estimate healthy organ equivalent dose saving. Use of a lead shield is justified. (paper)

Outdoor γ-ray dose rate in Ajigasawa Town and environmental factors affecting it in IES

International Nuclear Information System (INIS)

Iyogi, Takashi; Hisamatsu, Shunichi; Sakurai, Naoyuki; Koyama, Kenji

1999-01-01

We surveyed the outdoor γ-ray dose rate throughout Aomori Prefecture from 1991 to 1995, and found an annual mean dose rate of 46 nGy h -1 . Relatively high dose rates were also observed in several areas (municipalities) of the survey locations. In this study, we examined the detailed distribution of the γ-ray dose rate in one such high dose rate area, Ajigasawa Town. Glass dosimeters were used for the monitoring of cumulative γ-ray dose rate at 10 locations in the town. The dose rate from each radioactive nuclide in the ground at the monitoring locations was measured by using an in situ γ-ray spectrometer with a Ge detector. The results obtained with the glass dosimeters showed that the γ-ray dose rates in Ajigasawa Town varied from 48 to 57 nGy h -1 . Although the dose rates were generally higher than the mean dose in Aomori Prefecture (1992-1995), the rates were lower than other high dose rate areas which had already been measured. The in situ γ-ray spectrometry revealed that these relatively high dose rates were mainly caused by 40 K and Th series radionuclides in the town. The effect of meteorological conditions on the γ-ray dose rate was studied at a monitoring station in IES. The dose rate was continuously recorded by a DBM NaI(Tl) scintillation detector system. The mean dose rate obtained when precipitation was sensed was 27 nGy h -1 and higher than when no precipitation was sensed (23 nGy h -1 ). (author)

Endovascular Management of True Renal Arterial Aneurysms: Results from a Single Centre

Energy Technology Data Exchange (ETDEWEB)

Chung, Raymond, E-mail: chung.raymond.jh@alexandrahealth.com.sg [Khoo Teck Puat Hospital, Department of Radiology (Singapore); Touska, Philip, E-mail: p.touska@doctors.org.uk [St. George’s Hospital NHS Trust, Department of Radiology (United Kingdom); Morgan, Robert; Belli, Anna-Maria [St. George’s Hospital NHS Trust, Department of Interventional Radiology (United Kingdom)

2016-01-15

PurposeTo report a single centre’s experience of the endovascular treatment of renal arterial aneurysms, including techniques and outcomes.Materials and MethodsThis is a retrospective analysis of true renal arterial aneurysms (TRAAs) treated using endovascular techniques over a period of 12 years and 10 months. The clinical presentations, aneurysm characteristics, endovascular techniques and outcomes are reported.ResultsThere were nine TRAA cases with a mean aneurysm size of 21.0 mm, located at the main renal arterial bifurcation in all cases. Onyx{sup ®} was used as the embolic agent of choice (88.9 % cases), with concurrent balloon remodelling. The overall primary technical success rate was 100 %. Repeat intervention was carried out in 1 case, secondary to reperfusion >8 years post-initial treatment. Long-term clinical follow-up was available in 55.6 % of cases (mean 29.8 months; range 3.3–90.1 months). Early post-procedural renal function, as measured by serum creatinine, remained within the normal reference range. Renal parenchymal loss post-embolisation was ≤20 % in 77.8 % of cases, as estimated on imaging. Minor complications included non-target embolization of Onyx{sup ®} with no clinical sequelae (n = 1), transient pain requiring only oral analgesia with no prolongation of hospital stay (n = 2). No major complications occurred as a consequence of embolisation.ConclusionEndovascular therapy is an effective and safe primary therapy for TRAA with high success rate and low morbidity, supplanting surgery as primary therapy. Current experience in the use of Onyx{sup ®} in TRAA is primarily limited to individual case reports, and this represents the largest case series of Onyx{sup ®}-treated TRAAs to date.

The prediction of late rectal complications in patients treated with high dose-rate brachytherapy for carcinoma of the cervix

International Nuclear Information System (INIS)

Clark, Brenda G.; Souhami, Luis; Roman, Ted N.; Chappell, Rick; Evans, Michael D.C.; Fowler, Jack F.

1997-01-01

Purpose: The aim of this work is to investigate an unusually high rate of late rectal complications in a group of 43 patients treated with concomitant irradiation and chemotherapy for carcinoma of the cervix between December 1988 and April 1991, with a view to identifying predictive factors. Methods and Materials: The biologically effective dose received by each patient to the rectal reference point defined by the International Commission of Radiation Units and Measurements, Report 38, were calculated. Radiotherapy consisted of 46 Gy external beam irradiation plus three high dose-rate intracavitary treatments of 10 Gy each prescribed to point A. Cisplatin 30 mg/m 2 was given weekly throughout the duration of the irradiation. The results have been compared to data from 119 patients treated with irradiation alone to assess the confounding effect of the cisplatin. Results: The relationship between the biologically effective dose delivered to the rectal reference point and the development of late complications shows a strong dose-response with a threshold for complications occurring at approximately 125 Gy 3 corresponding to a brachytherapy dose of approximately 8 Gy per fraction. This value is approximately the same biologically effective dose threshold as that found for external beam irradiation in the head and neck region. The data from the group of patients treated without cisplatin is comparable to the data from the first group of patients in the lower dose ranges; the higher doses were not used and thus are not available for comparison. Conclusion: Using the linear quadratic model applied to our clinical results, we have established a threshold for late rectal complications for patients treated with external beam irradiation and high dose-rate brachytherapy for carcinoma of the cervix. This threshold is consistent with similar data for external beam irradiation in the head and neck region

Dose rate laser simulation tests adequacy: Shadowing and high intensity effects analysis

International Nuclear Information System (INIS)

Nikiforov, A.Y.; Skorobogatov, P.K.

1996-01-01

The adequacy of laser based simulation of the flash X-ray effects in microcircuits may be corrupted mainly due to laser radiation shadowing by the metallization and the non-linear absorption in a high intensity range. The numerical joint solution of the optical equations and the fundamental system of equations in a two-dimensional approximation were performed to adjust the application range of laser simulation. As a result the equivalent dose rate to laser intensity correspondence was established taking into account the shadowing as well as the high intensity effects. The simulation adequacy was verified in the range up to 4·10 11 rad(Si)/s with the comparative laser test of a specially designed test structure

Novel Use of the Contura for High Dose Rate Cranial Brachytherapy

International Nuclear Information System (INIS)

Scanderbeg, Daniel J.; Alksne, John F.; Lawson, Joshua D.; Murphy, Kevin T.

2011-01-01

A popular choice for treatment of recurrent gliomas was cranial brachytherapy using the GliaSite Radiation Therapy System. However, this device was taken off the market in late 2008, thus leaving a treatment void. This case study presents our experience treating a cranial lesion for the first time using a Contura multilumen, high-dose-rate (HDR) brachytherapy balloon applicator. The patient was a 47-year-old male who was diagnosed with a recurrent right frontal anaplastic oligodendroglioma. Previous radiosurgery made him a good candidate for brachytherapy. An intracavitary HDR balloon brachytherapy device (Contura) was placed in the resection cavity and treated with a single fraction of 20 Gy. The implant, treatment, and removal of the device were all completed without incident. Dosimetry of the device was excellent because the dose conformed very well to the target. V90, V100, V150, and V200 were 98.9%, 95.7%, 27.2, and 8.8 cc, respectively. This patient was treated successfully using the Contura multilumen balloon. Contura was originally designed for deployment in a postlumpectomy breast for treatment by accelerated partial breast irradiation. Being an intracavitary balloon device, its similarity to the GliaSite system makes it a viable replacement candidate. Multiple lumens in the device also make it possible to shape the dose delivered to the target, something not possible before with the GliaSite applicator.

Outcomes of Peripheral Endovascular Interventions Based on Hospital Volume: A Mini Review of Published Literature

Directory of Open Access Journals (Sweden)

Samir V Patel

2016-01-01

Full Text Available Previous literature showed hospital procedural volume is an independent predictor for outcomes of various cardiac procedures. However, very few studies shown similar results for peripheral endovascular interventions especially peripheral atherectomy. Here we are reviewing previously published articles to provide volume-outcome relationship for peripheral atherectomy and angioplasty with or without endovascular stenting. We found higher hospital volume significantly and independently lowers in-hospital mortality, amputation rates, peri-procedural complications, length and cost of hospitalization for peripheral endovascular interventions.

Pros and Cons of 3D Image Fusion in Endovascular Aortic Repair: A Systematic Review and Meta-analysis.

Science.gov (United States)

Goudeketting, Seline R; Heinen, Stefan G H; Ünlü, Çağdaş; van den Heuvel, Daniel A F; de Vries, Jean-Paul P M; van Strijen, Marco J; Sailer, Anna M

2017-08-01

To systematically review and meta-analyze the added value of 3-dimensional (3D) image fusion technology in endovascular aortic repair for its potential to reduce contrast media volume, radiation dose, procedure time, and fluoroscopy time. Electronic databases were systematically searched for studies published between January 2010 and March 2016 that included a control group describing 3D fusion imaging in endovascular aortic procedures. Two independent reviewers assessed the methodological quality of the included studies and extracted data on iodinated contrast volume, radiation dose, procedure time, and fluoroscopy time. The contrast use for standard and complex endovascular aortic repairs (fenestrated, branched, and chimney) were pooled using a random-effects model; outcomes are reported as the mean difference with 95% confidence intervals (CIs). Seven studies, 5 retrospective and 2 prospective, involving 921 patients were selected for analysis. The methodological quality of the studies was moderate (median 17, range 15-18). The use of fusion imaging led to an estimated mean reduction in iodinated contrast of 40.1 mL (95% CI 16.4 to 63.7, p=0.002) for standard procedures and a mean 70.7 mL (95% CI 44.8 to 96.6, p<0.001) for complex repairs. Secondary outcome measures were not pooled because of potential bias in nonrandomized data, but radiation doses, procedure times, and fluoroscopy times were lower, although not always significantly, in the fusion group in 6 of the 7 studies. Compared with the control group, 3D fusion imaging is associated with a significant reduction in the volume of contrast employed for standard and complex endovascular aortic procedures, which can be particularly important in patients with renal failure. Radiation doses, procedure times, and fluoroscopy times were reduced when 3D fusion was used.

Dose and dose rate effects of whole-body gamma-irradiation: II. Hematological variables and cytokines

Science.gov (United States)

Gridley, D. S.; Pecaut, M. J.; Miller, G. M.; Moyers, M. F.; Nelson, G. A.

2001-01-01

The goal of part II of this study was to evaluate the effects of gamma-radiation on circulating blood cells, functional characteristics of splenocytes, and cytokine expression after whole-body irradiation at varying total doses and at low- and high-dose-rates (LDR, HDR). Young adult C57BL/6 mice (n = 75) were irradiated with either 1 cGy/min or 80 cGy/min photons from a 60Co source to cumulative doses of 0.5, 1.5, and 3.0 Gy. The animals were euthanized at 4 days post-exposure for in vitro assays. Significant dose- (but not dose-rate-) dependent decreases were observed in erythrocyte and blood leukocyte counts, hemoglobin, hematocrit, lipopolysaccharide (LPS)-induced 3H-thymidine incorporation, and interleukin-2 (IL-2) secretion by activated spleen cells when compared to sham-irradiated controls (p factor-beta 1 (TGF-beta 1) and splenocyte secretion of tumor necrosis factor-alpha (TNF-alpha) were not affected by either the dose or dose rate of radiation. The data demonstrate that the responses of blood and spleen were largely dependent upon the total dose of radiation employed and that an 80-fold difference in the dose rate was not a significant factor in the great majority of measurements.

Gamma Low-Dose-Rate Ionizing Radiation Stimulates Adaptive Functional and Molecular Response in Human Aortic Endothelial Cells in a Threshold-, Dose-, and Dose Rate-Dependent Manner.

Science.gov (United States)

Vieira Dias, Juliana; Gloaguen, Celine; Kereselidze, Dimitri; Manens, Line; Tack, Karine; Ebrahimian, Teni G

2018-01-01

A central question in radiation protection research is whether low-dose and low-dose-rate (LDR) exposures to ionizing radiation play a role in progression of cardiovascular disease. The response of endothelial cells to different LDR exposures may help estimate risk of cardiovascular disease by providing the biological mechanism involved. We investigated the effect of chronic LDR radiation on functional and molecular responses of human aorta endothelial cells (HAoECs). Human aorta endothelial cells were continuously irradiated at LDR (6 mGy/h) for 15 days and analyzed at time points when the cumulative dose reached 0.05, 0.5, 1.0, and 2.0 Gy. The same doses were administered acutely at high-dose rate (HDR; 1 Gy/min). The threshold for the loss of angiogenic capacity for both LDR and HDR radiations was between 0.5 and 1.0 Gy. At 2.0 Gy, angiogenic capacity returned to normal only for HAoEC exposed to LDR radiation, associated with increased expression of antioxidant and anti-inflammatory genes. Pre-LDR, but not pre-HDR, radiation, followed by a single acute 2.0 Gy challenge dose sustained the expression of antioxidant and anti-inflammatory genes and stimulated angiogenesis. Our results suggest that dose rate is important in cellular response and that a radioadaptive response is involved for a 2.0 Gy dose at LDR.

Non-uniform dwell times in line source high dose rate brachytherapy: physical and radiobiological considerations

International Nuclear Information System (INIS)

Jones, B.; Tan, L.T.; Freestone, G.; Bleasdale, C.; Myint, S.; Littler, J.

1994-01-01

The ability to vary source dwell times in high dose rate (HDR) brachytherapy allows for the use of non-uniform dwell times along a line source. This may have advantages in the radical treatment of tumours depending on individual tumour geometry. This study investigates the potential improvements in local tumour control relative to adjacent normal tissue isoeffects when intratumour source dwell times are increased along the central portion of a line source (technique A) in radiotherapy schedules which include a relatively small component of HDR brachytherapy. Such a technique is predicted to increase the local control for tumours of diameters ranging between 2 cm and 4 cm by up to 11% compared with a technique in which there are uniform dwell times along the line source (technique B). There is no difference in the local control rates for the two techniques when used to treat smaller tumours. Normal tissue doses are also modified by the technique used. Technique A produces higher normal tissue doses at points perpendicular to the centre of the line source and lower dose at points nearer the ends of the line source if the prescription point is not in the central plane of the line source. Alternatively, if the dose is prescribed at a point in the central plane of the line source, the dose at all the normal tissue points are lower when technique A is used. (author)

High dose rate brachytherapy for medically inoperable stage I endometrial cancer

Energy Technology Data Exchange (ETDEWEB)

Petereit, Daniel G; Sarkaria, Jann N; Schink, Julian; Springman, Scott R; Kinsella, Timothy J; Buchler, Dolores A

1995-07-01

Purpose/Objective: To determine the efficacy of high dose rate (HDR) brachytherapy in patients with medically inoperable endometrial cancer clinically confined to the corpus. Materials and Methods: Forty-two patients with endometrial cancer and an intact uterus have been treated since 1989 with HDR brachytherapy. Twenty-six patients with medically inoperable Stage I disease were treated with radiation alone and form the basis of this study. Obesity was assessed using the body mass index (BMI kg/m{sup 2}) scale. Patients with a BMI above 28 were considered obese and those above 35 morbidly obese, per standard anesthesia guidelines. Brachytherapy was delivered in 5 HDR insertions, 1 week apart, without any external beam radiation. The following doses were delivered per insertion: 5.7 Gy to point S, 7.0 Gy to point W, 8.2 Gy to the vaginal surface and 9.2 Gy to point M. Point M represents the conventional point A dose, while points S and W are myometrial points. A single tandem with either ovoids or cylinders was placed, unless the uterine cavity would accommodate 2 tandems. All treatments were outpatient using intravenous fentanyl and midazolam for sedation. Pelvic ultrasound was commonly used at the time of brachytherapy to verify tandem placement. Three year clinical endpoints were calculated using the Kaplan Meier method. Results: The median follow-up for the study cohort was 21 months with follow-up greater than 36 months in 11 patients. Seventeen of the 26 patients were inoperable due to morbid obesity (median weight and BMI; 316 lbs and 55 kg/m{sup 2}, respectively); the other patients had poor cardiopulmonary reserve {+-} obesity. The median age, KPS (Karnofsky Performance Status), weight, ASA (American Society of Anesthesiologists' Physical Class System) and BMI were 63 yrs, 80%, 285 lbs, 3 and 49 kg/m{sup 2}, respectively. Two patients with an ASA of 3 and 4 died from acute cardio-pulmonary events within 30 days of the last insertion, emphasizing the need

High dose rate brachytherapy for medically inoperable stage I endometrial cancer

International Nuclear Information System (INIS)

Petereit, Daniel G.; Sarkaria, Jann N.; Schink, Julian; Springman, Scott R.; Kinsella, Timothy J.; Buchler, Dolores A.

1995-01-01

Purpose/Objective: To determine the efficacy of high dose rate (HDR) brachytherapy in patients with medically inoperable endometrial cancer clinically confined to the corpus. Materials and Methods: Forty-two patients with endometrial cancer and an intact uterus have been treated since 1989 with HDR brachytherapy. Twenty-six patients with medically inoperable Stage I disease were treated with radiation alone and form the basis of this study. Obesity was assessed using the body mass index (BMI kg/m 2 ) scale. Patients with a BMI above 28 were considered obese and those above 35 morbidly obese, per standard anesthesia guidelines. Brachytherapy was delivered in 5 HDR insertions, 1 week apart, without any external beam radiation. The following doses were delivered per insertion: 5.7 Gy to point S, 7.0 Gy to point W, 8.2 Gy to the vaginal surface and 9.2 Gy to point M. Point M represents the conventional point A dose, while points S and W are myometrial points. A single tandem with either ovoids or cylinders was placed, unless the uterine cavity would accommodate 2 tandems. All treatments were outpatient using intravenous fentanyl and midazolam for sedation. Pelvic ultrasound was commonly used at the time of brachytherapy to verify tandem placement. Three year clinical endpoints were calculated using the Kaplan Meier method. Results: The median follow-up for the study cohort was 21 months with follow-up greater than 36 months in 11 patients. Seventeen of the 26 patients were inoperable due to morbid obesity (median weight and BMI; 316 lbs and 55 kg/m 2 , respectively); the other patients had poor cardiopulmonary reserve ± obesity. The median age, KPS (Karnofsky Performance Status), weight, ASA (American Society of Anesthesiologists' Physical Class System) and BMI were 63 yrs, 80%, 285 lbs, 3 and 49 kg/m 2 , respectively. Two patients with an ASA of 3 and 4 died from acute cardio-pulmonary events within 30 days of the last insertion, emphasizing the need for accurate pre

A generic high-dose rate {sup 192}Ir brachytherapy source for evaluation of model-based dose calculations beyond the TG-43 formalism

Energy Technology Data Exchange (ETDEWEB)

Ballester, Facundo, E-mail: Facundo.Ballester@uv.es [Department of Atomic, Molecular and Nuclear Physics, University of Valencia, Burjassot 46100 (Spain); Carlsson Tedgren, Åsa [Department of Medical and Health Sciences (IMH), Radiation Physics, Faculty of Health Sciences, Linköping University, Linköping SE-581 85, Sweden and Department of Medical Physics, Karolinska University Hospital, Stockholm SE-171 76 (Sweden); Granero, Domingo [Department of Radiation Physics, ERESA, Hospital General Universitario, Valencia E-46014 (Spain); Haworth, Annette [Department of Physical Sciences, Peter MacCallum Cancer Centre and Royal Melbourne Institute of Technology, Melbourne, Victoria 3000 (Australia); Mourtada, Firas [Department of Radiation Oncology, Helen F. Graham Cancer Center, Christiana Care Health System, Newark, Delaware 19713 (United States); Fonseca, Gabriel Paiva [Instituto de Pesquisas Energéticas e Nucleares – IPEN-CNEN/SP, São Paulo 05508-000, Brazil and Department of Radiation Oncology (MAASTRO), GROW, School for Oncology and Developmental Biology, Maastricht University Medical Center, Maastricht 6201 BN (Netherlands); Zourari, Kyveli; Papagiannis, Panagiotis [Medical Physics Laboratory, Medical School, University of Athens, 75 MikrasAsias, Athens 115 27 (Greece); Rivard, Mark J. [Department of Radiation Oncology, Tufts University School of Medicine, Boston, Massachusetts 02111 (United States); Siebert, Frank-André [Clinic of Radiotherapy, University Hospital of Schleswig-Holstein, Campus Kiel, Kiel 24105 (Germany); Sloboda, Ron S. [Department of Medical Physics, Cross Cancer Institute, Edmonton, Alberta T6G 1Z2, Canada and Department of Oncology, University of Alberta, Edmonton, Alberta T6G 2R3 (Canada); and others

2015-06-15

Purpose: In order to facilitate a smooth transition for brachytherapy dose calculations from the American Association of Physicists in Medicine (AAPM) Task Group No. 43 (TG-43) formalism to model-based dose calculation algorithms (MBDCAs), treatment planning systems (TPSs) using a MBDCA require a set of well-defined test case plans characterized by Monte Carlo (MC) methods. This also permits direct dose comparison to TG-43 reference data. Such test case plans should be made available for use in the software commissioning process performed by clinical end users. To this end, a hypothetical, generic high-dose rate (HDR) {sup 192}Ir source and a virtual water phantom were designed, which can be imported into a TPS. Methods: A hypothetical, generic HDR {sup 192}Ir source was designed based on commercially available sources as well as a virtual, cubic water phantom that can be imported into any TPS in DICOM format. The dose distribution of the generic {sup 192}Ir source when placed at the center of the cubic phantom, and away from the center under altered scatter conditions, was evaluated using two commercial MBDCAs [Oncentra{sup ®} Brachy with advanced collapsed-cone engine (ACE) and BrachyVision ACUROS{sup TM}]. Dose comparisons were performed using state-of-the-art MC codes for radiation transport, including ALGEBRA, BrachyDose, GEANT4, MCNP5, MCNP6, and PENELOPE2008. The methodologies adhered to recommendations in the AAPM TG-229 report on high-energy brachytherapy source dosimetry. TG-43 dosimetry parameters, an along-away dose-rate table, and primary and scatter separated (PSS) data were obtained. The virtual water phantom of (201){sup 3} voxels (1 mm sides) was used to evaluate the calculated dose distributions. Two test case plans involving a single position of the generic HDR {sup 192}Ir source in this phantom were prepared: (i) source centered in the phantom and (ii) source displaced 7 cm laterally from the center. Datasets were independently produced by

Postoperative vaginal cuff irradiation using high dose rate remote afterloading: a Phase II clinical protocol

International Nuclear Information System (INIS)

Noyes, William R.; Bastin, Kenneth; Edwards, Scott A.; Buchler, Dolores A.; Stitt, Judith A.; Thomadsen, Bruce R.; Fowler, Jack F.; Kinsella, Timothy J.

1995-01-01

Purpose: In September 1989, a postoperative Phase II high dose rate (HDR) brachytherapy protocol was started for International Federation of Gynecology and Obstetrics (FIGO) Stage I endometrial adenocarcinoma. This review reports the overall survival, local control, and complication rates for the initial 63 patients treated in this Phase II study. Methods and Materials: High dose rate brachytherapy was delivered using an Iridium-192 HDR remote afterloader. Sixty-three patients were entered into the Phase II protocol, each receiving two vaginal cuff treatments 1 week apart (range 4-12 days) with vaginal ovoids (diameter 2.0-3.0 cm). No patient received adjuvant external beam radiation. A dose of 32.4 Gy in two fractions was prescribed to the ovoid surface in 63 patients. The first three patients treated at our institution received 15, 16.2, and 29 Gy, respectively, to determine acute effects. Results: At a median follow-up of 1.6 years (range 0.75-4.3 years) no patient has developed a vaginal cuff recurrence. One regional recurrence (1.6%) occurred at 1.2 years at the pelvic side wall. This patient is alive and without evidence of disease 7 months after completion of salvage irradiation, which resulted in the only vaginal stenosis (1.6%). Fourteen patients (22%) experienced vaginal apex fibrosis by physical exam, which was clinically symptomatic in four patients. Two patients reported stress incontinence; however, these symptoms were noted prior to their HDR therapy. One patient died 2.4 years after HDR therapy due to cardiovascular disease without evidence of cancer at autopsy. Conclusion: Preliminary results of our phase II HDR vaginal cuff protocol for postoperative FIGO Stage IA, Grade 3 or Stage IB, Grade 1-2 patients demonstrate that 32.4 Gy in two fractions is well tolerated by the vaginal cuff mucosa. Local control appears comparable to our prior experience and others with low dose rate (LDR) brachytherapy. Additional patient accrual and further follow

Human reliability in high dose rate afterloading radiotherapy based on FMECA

International Nuclear Information System (INIS)

Deng Jun; Fan Yaohua; Yue Baorong; Wei Kedao; Ren Fuli

2012-01-01

Objective: To put forward reasonable and feasible recommendations against the procedure with relative high risk during the high dose rate (HDR) afterloading radiotherapy, so as to enhance its clinical application safety, through studying the human reliability in the process of carrying out the HDR afterloading radiotherapy. Methods: Basic data were collected by on-site investigation and process analysis as well as expert evaluation. Failure mode, effect and criticality analysis (FMECA) employed to study the human reliability in the execution of HDR afterloading radiotherapy. Results: The FMECA model of human reliability for HDR afterloading radiotherapy was established, through which 25 procedures with relative high risk index were found,accounting for 14.1% of total 177 procedures. Conclusions: FMECA method in human reliability study for HDR afterloading radiotherapy is feasible. The countermeasures are put forward to reduce the human error, so as to provide important basis for enhancing clinical application safety of HDR afterloading radiotherapy. (authors)

Mid-Term Outcomes of Endovascular Treatment for TASC-II D Femoropopliteal Occlusive Disease with Critical Limb Ischemia

Energy Technology Data Exchange (ETDEWEB)

Torres-Blanco, Álvaro, E-mail: atorres658@yahoo.es; Edo-Fleta, Gemma; Gómez-Palonés, Francisco; Molina-Nácher, Vicente; Ortiz-Monzón, Eduardo [Hospital Universitario Dr. Peset, Department of Angiology, Endovascular and Vascular Surgery (Spain)

2016-03-15

PurposeThe purpose of the study was to assess the safety and midterm effectiveness of endovascular treatment in Trans-Atlantic Inter-Society Consensus II (TASC-II) D femoropopliteal occlusions in patients with critical limb ischemia (CLI).MethodsPatients with CLI who underwent endovascular treatment for TASC-D de novo femoropopliteal occlusive disease between September 2008 and December 2013 were selected. Data included anatomic features, pre- and postprocedure ankle-brachial index, duplex ultrasound, and periprocedural complications. Sustained clinical improvement, limb salvage rate, freedom from target lesion revascularization (TLR), and freedom from target extremity revascularization (TER) were assessed by Kaplan–Meier estimation and predictors of restenosis/occlusion with Cox analysis.ResultsThirty-two patients underwent treatment of 35 TASC-D occlusions. Mean age was 76 ± 9. Mean lesion length was 23 ± 5 cm. Twenty-eight limbs (80 %) presented tissue loss. Seventeen limbs underwent treatment by stent, 13 by stent-graft, and 5 by angioplasty. Mean follow-up was 29 ± 20 months. Seven patients required major amputation and six patients died during follow-up. Eighteen endovascular and three surgical TLR procedures were performed due to restenosis or occlusion. Estimated freedom from TLR and TER rates at 2 years were 41 and 76 %, whereas estimated primary and secondary patency rates were 41 and 79 %, respectively.ConclusionsEndovascular treatment for TASC II D lesions is safe and offers satisfying outcomes. This patient subset would benefit from a minimally invasive approach. Follow-up is advisable due to a high rate of restenosis. Further follow-up is necessary to know the long-term efficacy of these procedures.

Radiobiological equivalent of low/high dose rate brachytherapy and evaluation of tumor and normal responses to the dose.

Science.gov (United States)

Manimaran, S

2007-06-01

The aim of this study was to compare the biological equivalent of low-dose-rate (LDR) and high-dose-rate (HDR) brachytherapy in terms of the more recent linear quadratic (LQ) model, which leads to theoretical estimation of biological equivalence. One of the key features of the LQ model is that it allows a more systematic radiobiological comparison between different types of treatment because the main parameters alpha/beta and micro are tissue-specific. Such comparisons also allow assessment of the likely change in the therapeutic ratio when switching between LDR and HDR treatments. The main application of LQ methodology, which focuses on by increasing the availability of remote afterloading units, has been to design fractionated HDR treatments that can replace existing LDR techniques. In this study, with LDR treatments (39 Gy in 48 h) equivalent to 11 fractions of HDR irradiation at the experimental level, there are increasing reports of reproducible animal models that may be used to investigate the biological basis of brachytherapy and to help confirm theoretical predictions. This is a timely development owing to the nonavailability of sufficient retrospective patient data analysis. It appears that HDR brachytherapy is likely to be a viable alternative to LDR only if it is delivered without a prohibitively large number of fractions (e.g., fewer than 11). With increased scientific understanding and technological capability, the prospect of a dose equivalent to HDR brachytherapy will allow greater utilization of the concepts discussed in this article.

High dose rate brachytherapy for the treatment of soft tissue sarcoma of the extremity

International Nuclear Information System (INIS)

Speight, J.L.; Streeter, O.E.; Chawla, S.; Menendez, L.E.

1996-01-01

Purpose: we examined the role of preoperative neoadjuvant chemoradiation and adjuvant high-dose rate brachytherapy on the management of prognostically unfavorable soft tissue sarcomas of the extremities. Our goal was to examine the effect of high dose rate interstitial brachytherapy (HDR IBT) on reducing the risk of local recurrence following limb-sparing resection, as well as shortening treatment duration. Materials and methods: eleven patients, ranging in age from 31 to 73 years old, with soft tissue sarcoma of the extremity were treated at USC/Norris Comprehensive Cancer Center during 1994 and 1995. All patients had biopsy proven soft tissue sarcoma, and all were suitable candidates for limb-sparing surgery. All lesions were greater than 5cm in size and were primarily high grade. Tumor histologies included malignant fibrous histiocytoma (45%), liposarcoma (18%) and leiomyosarcoma, synovial cell sarcoma and spindle cell sarcoma (36%). Sites of tumor origin were the lower extremity (55%), upper extremity (18%) and buttock (9%), 1 patient (9%) had lesions in both the upper and lower extremity. Patients received HDR IBT following combined chemotherapy and external beam irradiation (EBRT) and en bloc resection of the sarcoma. Neoadjuvant chemotherapy consisted of three to four cycles of either Ifosfamide/Mesna with or without Adriamycin, or Mesna, Adriamycin, Ifosfamide and Dacarbazine. One patient received Cis-platin in addition to Ifos/Adr. A minimum of two cycles of chemotherapy were administered prior to EBRT. Additional cycles of chemotherapy were completed concurrently with EBRT but prior to HDR IBT. Preoperative EBRT doses ranging from 40 to 59.4 Gy were given in daily fractions of 180 to 200cGy. Following en bloc resection, HDR IBT was administered using the Omnitron tm 2000 remote afterloading system. Doses ranging from 13 to 30 Gy were delivered to the surgical tumor bed at depths of 0.5mm to 0.75mm from the radioactive source. Results: median follow-up was

ALARA-based strengthening of radiation protection in a high dose rate nuclear power plant: A practical overview

International Nuclear Information System (INIS)

Lips, Marcel

2008-01-01

In the first years of operation the dose rates at Goesgen nuclear power plant increased more strongly than expected. Co-60 has been the main radiation contributor from the beginning. As an immediate step, investigations were initiated to find and remove unknown cobalt sources. System modifications and optimization in water chemistry were carried out to reduce material and activity transport within the primary system. As a result the dose rates were stabilized after a couple of years -unfortunately on a high level. To reduce the dose rate levels and the occupational radiation exposure, further long term measures were implemented. System decontamination and source replacement were considered as well as the implementation of enhanced shielding procedures and a more source oriented chemistry. As a result the dose rates have reduced significantly and the occupational radiation exposure has been decreased by more than a factor of 2 over the last two decades. The reduction of the mean individual dose turned out even better and was cut by a factor of 5. On terms of plant and personal safety, Goesgen nuclear power plant decided to improve radiation protection using a smooth step by step action plan and has been very successful with it. Currently the technical possibilities have been developed to a high standard. Further improvements will be selective only. In future the focus will be set to personal behavior and human performance, using enhanced target settings, briefings, debriefings, experience feedback and (international) experience exchange. Nevertheless it will be essential to avoid unnecessary administrative and counterproductive short term hurdles. Strengthening of radiation protection is and will be a long term and continuous process. Goesgen nuclear power plant will continue to introduce further actions one by one. (author)

Terrestrial gamma ray dose rates on Ryoke granitic rocks in Ikoma Mountains

International Nuclear Information System (INIS)

Ikeda, Tadashi; Ueshima, Masaaki; Shibayama, Motohiko; Hiraoka, Yoshitsugu; Muslim, Dicky

2012-01-01

We measured the γ dose rate of 16 rock bodies in the field, which belonged to Ryoke granitic rocks distributed over Ikoma Mountains. The measurement points were 190 spots, and the mean dose rate was 82.0 ± 21.0 nGy/h. Results of analysis were summarized as follows. (1) The distribution of the dose rate in the Fukihata quartz diorite showed that the rocks crystallization differentiation had progressed from the south to the north. (2) The dose rate of granite tended to arise with the increase of SiO 2 quantity, but in the Iwahashiyama granite, the Takayasuyama granite, the Omichi granite and the Katakami granite, it was revealed that the dose rate was low in spite of high SiO 2 quantity. (3) It became clear that the dose rate of Ryoke granitic rocks from the first stage to the fourth stage was high to be considered as a new rock body. (4) Because the relationship between the dose rate of rocks and the main chemical elements did not show a common characteristic, it may be that those rocks were formed from different Magma. (author)

Content Validation and Evaluation of an Endovascular Teamwork Assessment Tool.

Science.gov (United States)

Hull, L; Bicknell, C; Patel, K; Vyas, R; Van Herzeele, I; Sevdalis, N; Rudarakanchana, N

2016-07-01

To modify, content validate, and evaluate a teamwork assessment tool for use in endovascular surgery. A multistage, multimethod study was conducted. Stage 1 included expert review and modification of the existing Observational Teamwork Assessment for Surgery (OTAS) tool. Stage 2 included identification of additional exemplar behaviours contributing to effective teamwork and enhanced patient safety in endovascular surgery (using real-time observation, focus groups, and semistructured interviews of multidisciplinary teams). Stage 3 included content validation of exemplar behaviours using expert consensus according to established psychometric recommendations and evaluation of structure, content, feasibility, and usability of the Endovascular Observational Teamwork Assessment Tool (Endo-OTAS) by an expert multidisciplinary panel. Stage 4 included final team expert review of exemplars. OTAS core team behaviours were maintained (communication, coordination, cooperation, leadership team monitoring). Of the 114 OTAS behavioural exemplars, 19 were modified, four removed, and 39 additional endovascular-specific behaviours identified. Content validation of these 153 exemplar behaviours showed that 113/153 (73.9%) reached the predetermined Item-Content Validity Index rating for teamwork and/or patient safety. After expert team review, 140/153 (91.5%) exemplars were deemed to warrant inclusion in the tool. More than 90% of the expert panel agreed that Endo-OTAS is an appropriate teamwork assessment tool with observable behaviours. Some concerns were noted about the time required to conduct observations and provide performance feedback. Endo-OTAS is a novel teamwork assessment tool, with evidence for content validity and relevance to endovascular teams. Endo-OTAS enables systematic objective assessment of the quality of team performance during endovascular procedures. Copyright © 2016. Published by Elsevier Ltd.

Tratamento endovascular de lesões arteriais traumáticas Endovascular management of traumatic arterial injuries

Directory of Open Access Journals (Sweden)

Ruy Fernandes e Fernandes

2011-03-01

. Todos os procedimentos foram realizados com sucesso. Não se verificou mortalidade. No doente com RAS houve necessidade de cirurgia de descorticação pulmonar esquerda, por hematoma organizado, e o doente com FAV foi submetido com sucesso a nova embolização com coils por recorrência precoce de hematúria. Conclusão: O tratamento endovascular é, em casos seleccionados, uma alternativa válida e menos invasiva de lesões traumáticas complexas em regiões anatómicas de difícil acesso e morbi-mortalidade cirúrgica elevada.Introduction: Traumatic vascular injuries are present in less than 10% of patients with multi-organ trauma and, in western countries, the incidence of iatrogenic vascular lesions has been increasing. Conventional surgery in the approach of these lesions usually requires extended surgical exposure, presents increased technical challenges and has high morbidity and mortality. Recently, several authors have described the successful management of traumatic injuries with endovascular techniques with diminished surgical risk. Endovascular surgery has also been increasingly applied in management of chronic traumatic injuries like chronic post-traumatic thoracic aneurysms with significant improved outcomes. The authors present clinical cases with several acute and chronic traumatic vascular injuries treated with endovascular techniques, Clinical reports: Seven patients (21-77 years with traumatic vascular injuries were treated. Four patients presented acute injuries: 1 case of traumatic aortic injury in a patient with multi-organ trauma after automobile crash; 1 case of iatrogenic subclavian artery rupture after inadvertent subclavian artery catheterization during attempted venous central access ; 1 case of iatrogenic renal artery rupture during renal angioplasty and stenting; 1 case of iatrogenic intra-renal arterio-venous fistula (AVF after laparoscopic resection of a renal tumour. Three patients presented with chronic post-traumatic thoracic aneurysms

Calibration of {sup 192}Ir high dose rate brachytherapy sources

Energy Technology Data Exchange (ETDEWEB)

Marechal, M H [Instituto de Radioprotecao e Dozimetria, Rio de Jainero (Brazil); Almeida, C.E. de [Laboratorio de Ciencias Radiologicas, UERL, Rio de Janeiro (Brazil); Sibata, C H [Roswell Park Cancer Inst., Buffalo, NY (United States)

1996-08-01

A method for calibration of high dose rate sources used in afterloading brachytherapy systems is described. The calibration for {sup 192}Ir is determined by interpolating {sup 60}Co gamma-rays and 250 kV x-rays calibration factors. All measurements were done using the same build up caps as described by Goetsch et al and recommended by AAPM. The attenuation correction factors were determined to be 0.9903, 0.9928 and 0.9993 for {sup 192}Ir, {sup 60}Co and 250 kV x-ray, respectively. A wall + cap thickness of 0.421 g.cm{sup -2} is recommended for all measurements to ensure electronic equilibrium for {sup 60}Co and {sup 192}Ir gamma-ray beams. A mathematical formalism is described for determination of (N{sub x}){sub Ir}. (author). 5 refs, 1 fig.

Rabbit models of cerebral vasospasm established with endovascular puncture

International Nuclear Information System (INIS)

Tu Jianfei; Liu Yizhi; Ji Jiansong; Zhao Zhongwei

2008-01-01

Objective: To investigate the method of endovascular puncture to establish rabbit models of cerebral vasospasm. Methods: New Zealand white rabbits were divided into 5 groups (12 h, 1 d, 2 d, 3 d and 7 d) randomly, and each group was separated into subarachnoid hemorrhage (SAH) subgroup (n=5) and control subgroup (n=2). cerebral vascular spasm (CVS) models were established after SAH with endovascular puncture. CT scans before and after operation were performed. The internal diameters and the wall thicknesses of posterior communicans artery (PcoA) and basilar artery (BA) were measured with HE stain after the animals were executed. Results: CVS model was successfully eastblished in 35 rabbits (SAH subgroup 25, control subgroup 10), resulting a successful rate of 48.61%. Compared with control subgroup, PcoA and BA showed shrinkage of internal diameters of 43.60% and 51.82% 12 h after SAH, respectively, and the shrinkage appeared as biphasic patterns until the 7th study day with another peaks of 29.32% and 45.19%, respectively. Conclusions: Endovascular puncture is an effective method to establish rabbit of CVS. The death rate of animals can be decreased with the asage of new interventional material and perfection for the details of operation. (authors)

High-dose-rate brachytherapy as salvage modality for locally recurrent prostate cancer after definitive radiotherapy. A systematic review

Energy Technology Data Exchange (ETDEWEB)

Chatzikonstantinou, Georgios; Zamboglou, Nikolaos; Roedel, Claus; Tselis, Nikolaos [J.W. Goethe University of Frankfurt, Department of Radiotherapy and Oncology, Frankfurt am Main (Germany); Zoga, Eleni [Sana Klinikum Offenbach, Department of Radiotherapy and Oncology, Offenbach am Main (Germany); Strouthos, Iosif [Medical Center - University of Freiburg, Department of Radiotherapy and Oncology, University of Freiburg, Freiburg (Germany); Butt, Saeed Ahmed [Sana Klinikum Offenbach, Department of Medical Physics and Engineering, Offenbach am Main (Germany)

2017-09-15

To review the current status of interstitial high-dose-rate brachytherapy as a salvage modality (sHDR BRT) for locally recurrent prostate cancer after definitive radiotherapy (RT). A literature search was performed in PubMed using ''high-dose-rate, brachytherapy, prostate cancer, salvage'' as search terms. In all, 51 search results published between 2000 and 2016 were identified. Data tables were generated and summary descriptions created. The main outcome parameters used were biochemical control (BC) and toxicity scores. Eleven publications reported clinical outcome and toxicity with follow-up ranging from 4-191 months. A variety of dose and fractionation schedules were described, including 19.0 Gy in 2 fractions up to 42.0 Gy in 6 fractions. The 5-year BC ranged from 18-77%. Late grade 3 genitourinary and gastrointestinal toxicity was 0-32% and 0-5.1%, respectively. sHDR BRT appears as safe and effective salvage modality for the reirradiation of locally recurrent prostate cancer after definitive RT. (orig.) [German] Zusammenfassende Darstellung relevanter Literatur zur interstitiellen High-Dose-Rate-Brachytherapie als Salvage-Modalitaet (sHDR-BRT) bei der Behandlung des lokal rezidivierten Prostatakarzinoms nach vorausgegangener definitiver Radiotherapie (RT). In der PubMed-Datenbank wurde eine Literaturrecherche mit den Suchbegriffen ''high-dose-rate, brachytherapy, prostate cancer, salvage'' durchgefuehrt. Zwischen den Jahren 2000 und 2016 wurden 51 Publikationen identifiziert. Die biochemische Kontrolle (BC) sowie das assoziierte Toxizitaetsprofil waren onkologische Hauptpunkte in der Analyse der beruecksichtigten Literatur. Von onkologischen Ergebnissen und Toxizitaeten berichteten 11 Publikationen bei einer medianen Nachbeobachtungszeit von 4-191 Monaten. Eine Variabilitaet von Dosis- und Fraktionierungsregimen wurde beschrieben mit totalen physikalischen Dosen von 19,0 Gy in 2 Fraktionen bis zu 42,0 Gy in 6 Fraktionen

Fiber optics in high dose radiation fields

International Nuclear Information System (INIS)

Partin, J.K.

1985-01-01

A review of the behavior of state-of-the-art optical fiber waveguides in high dose (greater than or equal to 10 5 rad), steady state radiation fields is presented. The influence on radiation-induced transmission loss due to experimental parameters such as dose rate, total dose, irradiation history, temperature, wavelength, and light intensity, for future work in high dose environments are given

Dose specification for 192Ir high dose rate brachytherapy in terms of dose-to-water-in-medium and dose-to-medium-in-medium

International Nuclear Information System (INIS)

Fonseca, Gabriel Paiva; Yoriyaz, Hélio; Tedgren, Åsa Carlsson; Nilsson, Josef; Persson, Maria; Reniers, Brigitte; Verhaegen, Frank

2015-01-01

Dose calculation in high dose rate brachytherapy with 192 Ir is usually based on the TG-43U1 protocol where all media are considered to be water. Several dose calculation algorithms have been developed that are capable of handling heterogeneities with two possibilities to report dose: dose-to-medium-in-medium (D m,m ) and dose-to-water-in-medium (D w,m ). The relation between D m,m and D w,m for 192 Ir is the main goal of this study, in particular the dependence of D w,m on the dose calculation approach using either large cavity theory (LCT) or small cavity theory (SCT). A head and neck case was selected due to the presence of media with a large range of atomic numbers relevant to tissues and mass densities such as air, soft tissues and bone interfaces. This case was simulated using a Monte Carlo (MC) code to score: D m,m, D w,m (LCT), mean photon energy and photon fluence. D w,m (SCT) was derived from MC simulations using the ratio between the unrestricted collisional stopping power of the actual medium and water. Differences between D m,m and D w,m (SCT or LCT) can be negligible (<1%) for some tissues e.g. muscle and significant for other tissues with differences of up to 14% for bone. Using SCT or LCT approaches leads to differences between D w,m (SCT) and D w,m (LCT) up to 29% for bone and 36% for teeth. The mean photon energy distribution ranges from 222 keV up to 356 keV. However, results obtained using mean photon energies are not equivalent to the ones obtained using the full, local photon spectrum. This work concludes that it is essential that brachytherapy studies clearly report the dose quantity. It further shows that while differences between D m,m and D w,m (SCT) mainly depend on tissue type, differences between D m,m and D w,m (LCT) are, in addition, significantly dependent on the local photon energy fluence spectrum which varies with distance to implanted sources. (paper)

Thoracic aortic aneurysms and dissections: endovascular treatment.

Science.gov (United States)

Baril, Donald T; Cho, Jae S; Chaer, Rabih A; Makaroun, Michel S

2010-01-01

The treatment of thoracic aortic disease has changed radically with the advances made in endovascular therapy since the concept of thoracic endovascular aortic repair was first described 15 years ago. Currently, there is a diverse array of endografts that are commercially available to treat the thoracic aorta. Multiple studies, including industry-sponsored and single-institution reports, have demonstrated excellent outcomes of thoracic endovascular aortic repair for the treatment of thoracic aortic aneurysms, with less reported perioperative morbidity and mortality in comparison with conventional open repair. Additionally, similar outcomes have been demonstrated for the treatment of type B dissections. However, the technology remains relatively novel, and larger studies with longer term outcomes are necessary to more fully evaluate the role of endovascular therapy for the treatment of thoracic aortic disease. This review examines the currently available thoracic endografts, preoperative planning for thoracic endovascular aortic repair, and outcomes of thoracic endovascular aortic repair for the treatment of both thoracic aortic aneurysms and type B aortic dissections. Mt Sinai J Med 77:256-269, 2010. (c) 2010 Mount Sinai School of Medicine.

Urethral stricture following high dose rate brachytherapy for prostate cancer

International Nuclear Information System (INIS)

Sullivan, Lisa; Williams, Scott G.; Tai, Keen Hun; Foroudi, Farshad; Cleeve, L.; Duchesne, Gillian M.

2009-01-01

Purpose: To evaluate the incidence, timing, nature and outcome of urethral strictures following high dose rate brachytherapy (HDRB) for prostate carcinoma. Methods and materials: Data from 474 patients with clinically localised prostate cancer treated with HDRB were analysed. Ninety percent received HDRB as a boost to external beam radiotherapy (HDRBB) and the remainder as monotherapy (HDRBM). Urethral strictures were graded according to the Common Terminology Criteria for Adverse Events v3.0. Results: At a median follow-up of 41 months, 38 patients (8%) were diagnosed with a urethral stricture (6-year actuarial risk 12%). Stricture location was bulbo-membranous (BM) urethra in 92.1%. The overall actuarial rate of grade 2 or more BM urethral stricture was estimated at 10.8% (95% CI 7.0-14.9%), with a median time to diagnosis of 22 months (range 10-68 months). All strictures were initially managed with either dilatation (n = 15) or optical urethrotomy (n = 20). Second line therapy was required in 17 cases (49%), third line in three cases (9%) and 1 patient open urethroplasty (grade 3 toxicity). Predictive factors on multivariate analysis were prior trans-urethral resection of prostate (hazard ratio (HR) 2.81, 95% CI 1.15-6.85, p = 0.023); hypertension (HR 2.83, 95% CI 1.37-5.85, p = 0.005); and dose per fraction used in HDR (HR for 1 Gy increase per fraction 1.33, 95% CI 1.08-1.64, p = 0.008). Conclusions: BM urethral strictures are the most common late grade 2 or more urinary toxicity following HDR brachytherapy for prostate cancer. Most are manageable with minimally invasive procedures. Both clinical and dosimetric factors appear to influence the risk of stricture formation.

Objective method to report planner-independent skin/rib maximal dose in balloon-based high dose rate (HDR) brachytherapy for breast cancer

International Nuclear Information System (INIS)

Kim, Yongbok; Trombetta, Mark G.

2011-01-01

Purpose: An objective method was proposed and compared with a manual selection method to determine planner-independent skin and rib maximal dose in balloon-based high dose rate (HDR) brachytherapy planning. Methods: The maximal dose to skin and rib was objectively extracted from a dose volume histogram (DVH) of skin and rib volumes. A virtual skin volume was produced by expanding the skin surface in three dimensions (3D) external to the breast with a certain thickness in the planning computed tomography (CT) images. Therefore, the maximal dose to this volume occurs on the skin surface the same with a conventional manual selection method. The rib was also delineated in the planning CT images and its maximal dose was extracted from its DVH. The absolute (Abdiff=|D max Man -D max DVH |) and relative (Rediff[%]=100x(|D max Man -D max DVH |)/D max DVH ) maximal skin and rib dose differences between the manual selection method (D max Man ) and the objective method (D max DVH ) were measured for 50 balloon-based HDR (25 MammoSite and 25 Contura) patients. Results: The average±standard deviation of maximal dose difference was 1.67%±1.69% of the prescribed dose (PD). No statistical difference was observed between MammoSite and Contura patients for both Abdiff and Rediff[%] values. However, a statistically significant difference (p value max >90%) compared with lower dose range (D max <90%): 2.16%±1.93% vs 1.19%±1.25% with p value of 0.0049. However, the Rediff[%] analysis eliminated the inverse square factor and there was no statistically significant difference (p value=0.8931) between high and low dose ranges. Conclusions: The objective method using volumetric information of skin and rib can determine the planner-independent maximal dose compared with the manual selection method. However, the difference was <2% of PD, on average, if appropriate attention is paid to selecting a manual dose point in 3D planning CT images.

Dose rate considerations in brachytherapy: biological equivalence of LDR and HDR

International Nuclear Information System (INIS)

Orton, C.G.

1994-01-01

The linear-quadratic model for cell survival and bioeffect doses is discussed and equations for low dose rate (LDR), high dose rate (HDR) and intermediate situations are presented. The model, when used to define LDR and single fractions of HDR, shows, that these correspond to irradiations lasting longer than about 14 hours or shorter than about 0.7 hours, respectively. It is shown that, for HDR to be as safe and effective as LDR, the dose-rate effect of LDR has to be replaced by the fractionation-effect of HDR. This is necessary in order to take advantage of the differential repair characteristics between late-reacting normal tissue and tumor cells at low doses and low dose rates. Using the linear-quadratic model to simulate repair mathematically, it is shown that the number of fractions required is highly dependent upon what parameters are assumed for normal tissues and tumor, as well as whether or not there is any physical advantage gained by conversion from LDR to HDR. (author). 20 refs., 7 figs

Reference Dose Rates for Fluoroscopy Guided Interventions

International Nuclear Information System (INIS)

Geleijns, J.; Broerse, J.J.; Hummel, W.A.; Schalij, M.J.; Schultze Kool, L.J.; Teeuwisse, W.; Zoetelief, J.

1998-01-01

The wide diversity of fluoroscopy guided interventions which have become available in recent years has improved patient care. They are being performed in increasing numbers, particularly at departments of cardiology and radiology. Some procedures are very complex and require extended fluoroscopy times, i.e. longer than 30 min, and radiation exposure of patient and medical staff is in some cases rather high. The occurrence of radiation-induced skin injuries on patients has shown that radiation protection for fluoroscopy guided interventions should not only be focused on stochastic effects, i.e. tumour induction and hereditary risks, but also on potential deterministic effects. Reference dose levels are introduced by the Council of the European Communities as an instrument to achieve optimisation of radiation protection in radiology. Reference levels in conventional diagnostic radiology are usually expressed as entrance skin dose or dose-area product. It is not possible to define a standard procedure for complex interventions due to the large inter-patient variations with regard to the complexity of specific interventional procedures. Consequently, it is not realistic to establish a reference skin dose or dose-area product for complex fluoroscopy guided interventions. As an alternative, reference values for fluoroscopy guided interventions can be expressed as the entrance dose rates on a homogeneous phantom and on the image intensifier. A protocol has been developed and applied during a nationwide survey of fluoroscopic dose rate during catheter ablations. From this survey reference entrance dose rates of respectively 30 mGy.min -1 on a polymethylmethacrylate (PMMA) phantom with a thickness of 21 cm, and of 0.8 μGy.s -1 on the image intensifier have been derived. (author)

Novel use of the Contura for high dose rate cranial brachytherapy.

Science.gov (United States)

Scanderbeg, Daniel J; Alksne, John F; Lawson, Joshua D; Murphy, Kevin T

2011-01-01

A popular choice for treatment of recurrent gliomas was cranial brachytherapy using the GliaSite Radiation Therapy System. However, this device was taken off the market in late 2008, thus leaving a treatment void. This case study presents our experience treating a cranial lesion for the first time using a Contura multilumen, high-dose-rate (HDR) brachytherapy balloon applicator. The patient was a 47-year-old male who was diagnosed with a recurrent right frontal anaplastic oligodendroglioma. Previous radiosurgery made him a good candidate for brachytherapy. An intracavitary HDR balloon brachytherapy device (Contura) was placed in the resection cavity and treated with a single fraction of 20 Gy. The implant, treatment, and removal of the device were all completed without incident. Dosimetry of the device was excellent because the dose conformed very well to the target. V90, V100, V150, and V200 were 98.9%, 95.7%, 27.2, and 8.8 cc, respectively. This patient was treated successfully using the Contura multilumen balloon. Contura was originally designed for deployment in a postlumpectomy breast for treatment by accelerated partial breast irradiation. Being an intracavitary balloon device, its similarity to the GliaSite system makes it a viable replacement candidate. Multiple lumens in the device also make it possible to shape the dose delivered to the target, something not possible before with the GliaSite applicator. Copyright © 2011 American Association of Medical Dosimetrists. Published by Elsevier Inc. All rights reserved.

Endovascular Procedures in Treatment of Infrapopliteal Arterial Occlusive Disease: Single Center Experience With 69 Infrapopliteal Procedures.

Science.gov (United States)

Janko, Pasternak J; Nebojsa, Budakov B; Andrej, Petres V

2018-03-01

Peripheral arterial occlusive disease (PAD) includes acute and chronic disorders of the blood supply as a result of obstruction of blood flow in the arteries of the limb. Treatment of PAD can be conservative, surgical and endovascular. Percutaneous transluminal angioplasty with or without stenting has become a recognized method, which is increasingly used in treatment of arterial occlusive disease. This study aimed to determine early results of endovascular treatment of critical limb ischemia (CLI) patients with infrapopliteal lesions. The study included 69 patients (46 men; mean age 65 years, range 38-84) with CLI (class 4 to 6 according to Rutherford). The primary study endpoints were absence of major amputation of the target limb at 6 months and occurance of local and systemic complications specifically related to use of endovascular treatment. Major amputation was avoided in 61 patients. Through 6 months, 6 patients underwent additional revascularization. One local complication (clinicaly significant dissection of popliteal artery) occurred, and it was resolved by stent implantation. There were no cases of systemic complications and death during the follow-up period. Rates of major amputation were 12.3% for diabetics versus 8.3% for non-diabetics. Our data showed that endovascular treatment of infrapopliteal disease is an effective and safe treatment in patients experiencing CLI, provides high limb preservation and low complication rates. Study outcomes support endovascular treatment as a primary option for patients experiencing CLI due to below the knee (BTK) occlusive disease. © 2018 The Author(s). This is an open-access article distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/4.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

Collection of radiation resistant characteristics reports for instruments and materials in high dose rate environment

International Nuclear Information System (INIS)

Kusano, Joichi

2008-03-01

This document presents the collected official reports of radiation irradiation study for the candidate materials to be used in high dose rate environment as J-PARC facility. The effect of radiation damage by loss-beam or secondary particle beam of the accelerators influences the performance and the reliability of various instruments. The knowledge on the radiation resistivity of the materials is important to estimate the life of the equipments, the maintenance interval and dose evaluation for the personnel at the maintenance period. The radiation damage consists with mechanical property, electrical property and gas-evolution property. (author)

Dose rate visualization of radioisotope thermoelectric generators

International Nuclear Information System (INIS)

Schwarz, R.A.; Kessler, S.F.; Tomaszewski, T.A.

1995-09-01

Advanced visualization techniques can be used to investigate gamma ray and neutron dose rates around complex dose rate intensive operations. A method has been developed where thousands of dose points are calculated using the MCNP(Monte Carlo N-Particle) computer code and then displayed to create color contour plots of the dose rate for complex geometries. Once these contour plots are created, they are sequenced together creating an animation to dynamically show how the dose rate changes with changes in the geometry or source over time

Biological responses to low dose rate gamma radiation

International Nuclear Information System (INIS)

Magae, Junji; Ogata, Hiromitsu

2003-01-01

Linear non-threshold (LNT) theory is a basic theory for radioprotection. While LNT dose not consider irradiation time or dose-rate, biological responses to radiation are complex processes dependent on irradiation time as well as total dose. Moreover, experimental and epidemiological studies that can evaluate LNT at low dose/low dose-rate are not sufficiently accumulated. Here we analyzed quantitative relationship among dose, dose-rate and irradiation time using chromosomal breakage and proliferation inhibition of human cells as indicators of biological responses. We also acquired quantitative data at low doses that can evaluate adaptability of LNT with statistically sufficient accuracy. Our results demonstrate that biological responses at low dose-rate are remarkably affected by exposure time, and they are dependent on dose-rate rather than total dose in long-term irradiation. We also found that change of biological responses at low dose was not linearly correlated to dose. These results suggest that it is necessary for us to create a new model which sufficiently includes dose-rate effect and correctly fits of actual experimental and epidemiological results to evaluate risk of radiation at low dose/low dose-rate. (author)

High-Dose-Rate Endobronchial Brachytherapy for Recurrent Airway Obstruction From Hyperplastic Granulation Tissue

International Nuclear Information System (INIS)

Tendulkar, Rahul D.; Fleming, Peter A.; Reddy, Chandana A.; Gildea, Thomas R.; Machuzak, Michael; Mehta, Atul C.

2008-01-01

Purpose: Benign endobronchial granulation tissue causes airway obstruction in up to 20% of patients after lung transplantation or stent placement. High-dose-rate endobronchial brachytherapy (HDR-EB) has been successful in some cases refractory to standard bronchoscopic interventions. Methods and Materials: Between September 2004 and May 2005, 8 patients with refractory benign airway obstruction were treated with HDR-EB, using one to two fractions of Ir-192 prescribed to 7.1 Gy at a radius of 1 cm. Charts were retrospectively reviewed to evaluate subjective clinical response, forced expiratory volume in 1 second (FEV 1 ), and frequency of therapeutic bronchoscopies over 6-month periods before and after HDR-EB. Results: The median follow-up was 14.6 months, and median survival was 10.5 months. The mean number of bronchoscopic interventions improved from 3.1 procedures in the 6-month pretreatment period to 1.8 after HDR-EB. Mean FEV 1 improved from 36% predicted to 46% predicted. Six patients had a good-to-excellent subjective early response, but only one maintained this response beyond 6 months, and this was the only patient treated with HDR-EB within 24 h from the most recent bronchoscopic intervention. Five patients have expired from causes related to their chronic pulmonary disease, including one from hemoptysis resulting from a bronchoarterial fistula. Conclusion: High-dose-rate-EB may be an effective treatment for select patients with refractory hyperplastic granulation tissue causing recurrent airway stenosis. Performing HDR-EB within 24-48 h after excision of obstructive granulation tissue could further improve outcomes. Careful patient selection is important to maximize therapeutic benefit and minimize toxicity. The optimal patient population, dose, and timing of HDR-EB should be investigated prospectively

On the impact of improved dosimetric accuracy on head and neck high dose rate brachytherapy.

Science.gov (United States)

Peppa, Vasiliki; Pappas, Eleftherios; Major, Tibor; Takácsi-Nagy, Zoltán; Pantelis, Evaggelos; Papagiannis, Panagiotis

2016-07-01

To study the effect of finite patient dimensions and tissue heterogeneities in head and neck high dose rate brachytherapy. The current practice of TG-43 dosimetry was compared to patient specific dosimetry obtained using Monte Carlo simulation for a sample of 22 patient plans. The dose distributions were compared in terms of percentage dose differences as well as differences in dose volume histogram and radiobiological indices for the target and organs at risk (mandible, parotids, skin, and spinal cord). Noticeable percentage differences exist between TG-43 and patient specific dosimetry, mainly at low dose points. Expressed as fractions of the planning aim dose, percentage differences are within 2% with a general TG-43 overestimation except for the spine. These differences are consistent resulting in statistically significant differences of dose volume histogram and radiobiology indices. Absolute differences of these indices are however small to warrant clinical importance in terms of tumor control or complication probabilities. The introduction of dosimetry methods characterized by improved accuracy is a valuable advancement. It does not appear however to influence dose prescription or call for amendment of clinical recommendations for the mobile tongue, base of tongue, and floor of mouth patient cohort of this study. Copyright © 2016 Elsevier Ireland Ltd. All rights reserved.

Effects of prescription depth, cylinder size, treatment length, tip space, and curved end on doses in high-dose-rate vaginal brachytherapy

International Nuclear Information System (INIS)

Li Shidong; Aref, Ibrahim; Walker, Eleanor; Movsas, Benjamin

2007-01-01

Purpose: To determine the effects of the prescription depth, cylinder size, treatment length, tip space, and curved end on high-dose-rate vaginal brachytherapy (HDR-VBT) of endometrial cancer. Methods and Materials: Treatment plans were prescribed and optimized based on points at the cylinder surface or at 0.5-cm depth. Cylinder sizes ranging from 2 to 4 cm in diameter, and treatment lengths ranging from 3 to 8 cm were used. Dose points in various depths were precisely defined along the cylinder dome. The given dose and dose uniformity to a depth of interest were measured by the mean dose (MD) and standard deviation (SD), respectively, among the dose points belonging to the depth. Dose fall-off beyond the 0.5 cm treatment depth was determined by the ratio of MD at 0.75-cm depth to MD at 0.5-cm depth. Results: Dose distribution varies significantly with different prescriptions. The surface prescription provides more uniform doses at all depths in the target volume, whereas the 0.5-cm depth prescription creates larger dose variations at the cylinder surface. Dosimetric uncertainty increases significantly (>30%) with shorter tip space. Extreme hot (>150%) and cold spots (<60%) occur if no optimization points were placed at the curved end. Conclusions: Instead of prescribing to a depth of 0.5 cm, increasing the dose per fraction and prescribing to the surface with the exact surface points around the cylinder dome appears to be the optimal approach

High dose rate brachytherapy for carcinoma of the cervix: risk factors for late rectal complications

International Nuclear Information System (INIS)

Uno, Takashi; Itami, Jun; Aruga, Moriyo; Kotaka, Kikuo; Fujimoto, Hajime; Minoura, Shigeki

1996-01-01

Purpose/Objective: To determine the incidence of late rectal complications in patients treated with high dose rate brachytherapy for FIGO stage IIB, IIIB carcinoma of the uterine cervix, and to evaluate the treatment factors associated with an increased probability of treatment complications. Materials and Methods: Records of 100 patients with FIGO IIB or IIIB cervical carcinoma treated with definitive irradiation using high dose rate intracavitary brachytherapy (HDR-ICR) between 1977 and 1994 were retrospectively reviewed. For each HDR-ICR session, 6 Gy isodose volume was reconstructed three dimensionally and the following three parameters were determined to represent this isodose volume, length (L); maximum longitudinal distance of 6 Gy isodose area in an oblique frontal plane containing the intrauterine applicator, width (W); maximum width of 6 Gy isodose area in the same plane, height (H); maximum dimension of 6 Gy isodose area perpendicular to the intrauterine applicator determined in the oblique sagittal plane. Point P/Q (2 cm ventral/dorsal from the proximal retention point of the intrauterine source) and point R/S (2 cm ventral/dorsal from the midpoint of the ovoid sources) were also defined retrospectively and HDR-ICR dose at these points were calculated. Statistical analyses were performed to determine the treatment factors predictive of late rectal complications. Results: The 5-year cumulative cause-specific disease-free survival rate was 50% for all, 74% for Stage IIB, and 38% for Stage IIIB, with a significant difference between two FIGO Stages (p=0.0004). Of patients treated for both stages, 30% and 36% had experienced moderate to severe (Grade 2-4) complications at 3 and 5 years, respectively. Average H value (p=0.013) and cumulative point S dose by HDR-ICR (p=0.020) were significantly correlated with the incidence of late rectal complications (Student's t-test), whereas these factors did not significantly affect the probability of pelvic control. No

Needle migration and dosimetric impact in high-dose-rate brachytherapy for prostate cancer evaluated by repeated MRI.

Science.gov (United States)

Buus, Simon; Lizondo, Maria; Hokland, Steffen; Rylander, Susanne; Pedersen, Erik M; Tanderup, Kari; Bentzen, Lise

To quantify needle migration and dosimetric impact in high-dose-rate brachytherapy for prostate cancer and propose a threshold for needle migration. Twenty-four high-risk prostate cancer patients treated with an HDR boost of 2 × 8.5 Gy were included. Patients received an MRI for planning (MRI1), before (MRI2), and after treatment (MRI3). Time from needle insertion to MRI3 was ∼3 hours. Needle migration was evaluated from coregistered images: MRI1-MRI2 and MRI1-MRI3. Dose volume histogram parameters from the treatment plan based on MRI1 were related to parameters based on needle positions in MRI2 or MRI3. Regression was used to model the average needle migration per implant and change in D90 clinical target volume, CTV prostate+3mm . The model fit was used for estimating the dosimetric impact in equivalent dose in 2 Gy fractions for dose levels of 6, 8.5, 10, 15, and 19 Gy. Needle migration was on average 2.2 ± 1.8 mm SD from MRI1-MRI2 and 5.0 ± 3.0 mm SD from MRI1-MRI3. D90 CTV prostate+3mm was robust toward average needle migration ≤3 mm, whereas for migration >3 mm D90 decreased by 4.5% per mm. A 3 mm of needle migration resulted in a decrease of 0.9, 1.7, 2.3, 4.8, and 7.6 equivalent dose in 2 Gy fractions for dose levels of 6, 8.5, 10, 15, and 19 Gy, respectively. Substantial needle migration in high-dose-rate brachytherapy occurs frequently in 1-3 hours following needle insertion. A 3-mm threshold of needle migration is proposed, but 2 mm may be considered for dose levels ≥15 Gy. Copyright © 2017 American Brachytherapy Society. Published by Elsevier Inc. All rights reserved.

Dose rate visualization of radioisotope thermoelectric generators

International Nuclear Information System (INIS)

Schwarz, R.A.; Kessler, S.F.; Tomaszewski, T.A.

1996-01-01

Advanced visualization techniques can be used to investigate gamma ray and neutron dose rates around complex dose rate intensive operations. A method has been developed where thousands of dose points are calculated using the MCNP (Monte Carlo N-Particle) computer code (Briesmeister 1993) and then displayed to create color contour plots of the dose rate for complex geometries. Once these contour plots are created, they are sequenced together creating an animation to dynamically show how the dose rate changes with changes in the geometry or source over time. copyright 1996 American Institute of Physics

Advances in endovascular treatment of critical limb ischemia.

LENUS (Irish Health Repository)

Yan, Bryan P

2011-04-01

Critical limb ischemia (CLI) represents the most severe clinical manifestation of peripheral arterial disease. In the absence of timely revascularization, CLI carries high risk of mortality and amputation. Over the past decade, endovascular revascularization has rapidly become the preferred primary treatment strategy for CLI, especially for the treatment of below-the-knee disease. Advances in percutaneous devices and techniques have expanded the spectrum of patients with CLI who are deemed candidates for revascularization. This review will focus on advances in endovascular options for the treatment of CLI, in particular for below-the-knee disease.

Distal posterior cerebral artery aneurysms: Retrospective review of characteristics and endovascular treatment

International Nuclear Information System (INIS)

Baek, Jin Wook; Jeong, Bae Woong; Seung, Won Bae

2016-01-01

The objective of this study was to review the clinical outcome after treatment of distal posterior cerebral artery (PCA) aneurysms via endovascular approach. Eleven patients with 11 distal PCA aneurysms who were treated via endovascular approach in Inje University Busan Paik Hospital and Kosin University Gospel Hospital from December 2002 to December 2013 were retrospectively reviewed. Among the 11 patients, there were 3 males (27.3%) and 8 females (72.7%). The mean age was 56.6 years (range 44 -72 years) and the mean aneurysm size was 8.45 mm (3 - 30 mm). Four (36.4%) aneurysms were located in the P2 segment, 6 (54.5%) in the P3 segment and 1 (9.1%) in the P1/2 junction. Seven (63.6%) aneurysms were treated with preservation of the parent artery; and the remaining 4 (36.4%) aneurysms were treated with parent artery occlusion. After treatment, the overall complication rate was 27% with the morbidity rate of 9.1% and the mortality rate of 18%. Endovascular treatment of distal PCA aneurysm might be used to minimize neurologic deficit, considering the diverse and rich collaterals of posterior cerebral artery

Distal posterior cerebral artery aneurysms: Retrospective review of characteristics and endovascular treatment

Energy Technology Data Exchange (ETDEWEB)

Baek, Jin Wook [Dept. of Radiology, Samsung Medical Center, Sungkyunkwan University School of Medicine, Seoul (Korea, Republic of); Jeong, Bae Woong [Dept. of Diagnostic Radiology, Inje University College of Medicine, Busan Paik Hospital, Busan (Korea, Republic of); Seung, Won Bae [Dept. of Neurosurgery, Kosin University College of Medicine, Gospel Hospital, Busan (Korea, Republic of)

2016-04-15

The objective of this study was to review the clinical outcome after treatment of distal posterior cerebral artery (PCA) aneurysms via endovascular approach. Eleven patients with 11 distal PCA aneurysms who were treated via endovascular approach in Inje University Busan Paik Hospital and Kosin University Gospel Hospital from December 2002 to December 2013 were retrospectively reviewed. Among the 11 patients, there were 3 males (27.3%) and 8 females (72.7%). The mean age was 56.6 years (range 44 -72 years) and the mean aneurysm size was 8.45 mm (3 - 30 mm). Four (36.4%) aneurysms were located in the P2 segment, 6 (54.5%) in the P3 segment and 1 (9.1%) in the P1/2 junction. Seven (63.6%) aneurysms were treated with preservation of the parent artery; and the remaining 4 (36.4%) aneurysms were treated with parent artery occlusion. After treatment, the overall complication rate was 27% with the morbidity rate of 9.1% and the mortality rate of 18%. Endovascular treatment of distal PCA aneurysm might be used to minimize neurologic deficit, considering the diverse and rich collaterals of posterior cerebral artery.

Atmospheric radiation flight dose rates

Science.gov (United States)

Tobiska, W. K.

2015-12-01

Space weather's effects upon the near-Earth environment are due to dynamic changes in the energy transfer processes from the Sun's photons, particles, and fields. Of the domains that are affected by space weather, the coupling between the solar and galactic high-energy particles, the magnetosphere, and atmospheric regions can significantly affect humans and our technology as a result of radiation exposure. Space Environment Technologies (SET) has been conducting space weather observations of the atmospheric radiation environment at aviation altitudes that will eventually be transitioned into air traffic management operations. The Automated Radiation Measurements for Aerospace Safety (ARMAS) system and Upper-atmospheric Space and Earth Weather eXperiment (USEWX) both are providing dose rate measurements. Both activities are under the ARMAS goal of providing the "weather" of the radiation environment to improve aircraft crew and passenger safety. Over 5-dozen ARMAS and USEWX flights have successfully demonstrated the operation of a micro dosimeter on commercial aviation altitude aircraft that captures the real-time radiation environment resulting from Galactic Cosmic Rays and Solar Energetic Particles. The real-time radiation exposure is computed as an effective dose rate (body-averaged over the radiative-sensitive organs and tissues in units of microsieverts per hour); total ionizing dose is captured on the aircraft, downlinked in real-time, processed on the ground into effective dose rates, compared with NASA's Langley Research Center (LaRC) most recent Nowcast of Atmospheric Ionizing Radiation System (NAIRAS) global radiation climatology model runs, and then made available to end users via the web and smart phone apps. Flight altitudes now exceed 60,000 ft. and extend above commercial aviation altitudes into the stratosphere. In this presentation we describe recent ARMAS and USEWX results.

VMATc: VMAT with constant gantry speed and dose rate

International Nuclear Information System (INIS)

Peng, Fei; Romeijn, H Edwin; Epelman, Marina A; Jiang, Steve B

2015-01-01

This article considers the treatment plan optimization problem for Volumetric Modulated Arc Therapy (VMAT) with constant gantry speed and dose rate (VMATc). In particular, we consider the simultaneous optimization of multi-leaf collimator leaf positions and a constant gantry speed and dose rate. We propose a heuristic framework for (approximately) solving this optimization problem that is based on hierarchical decomposition. Specifically, an iterative algorithm is used to heuristically optimize dose rate and gantry speed selection, where at every iteration a leaf position optimization subproblem is solved, also heuristically, to find a high-quality plan corresponding to a given dose rate and gantry speed. We apply our framework to clinical patient cases, and compare the resulting VMATc plans to idealized IMRT, as well as full VMAT plans. Our results suggest that VMATc is capable of producing treatment plans of comparable quality to VMAT, albeit at the expense of long computation time and generally higher total monitor units. (paper)

High-dose rate fractionated interstitial radiotherapy for oropharyngeal carcinoma

Energy Technology Data Exchange (ETDEWEB)

Nose, Takayuki; Inoue, Toshihiko; Inoue, Takehiro; Teshima, Teruki; Murayama, Shigeyuki [Osaka Univ. (Japan). Faculty of Medicine

1995-03-01

The limitations of treating oropharyngeal cancer patients with definitive external radiotherapy are the complications of salivary glands, taste buds, mandible and temporomandibular joints. To avoid these complications we started interstitial radiotherapy as boost after 46 Gy of external radiotherapy. Ten cases (retromolar trigone; 1, soft palate; 1, base of tongue; 3, lateral wall; 5) were treated with this method and seven cases were controlled locally. With short follow-up period, xerostomia and dysgeusia are less than definitive external radiotherapy as clinical impression and no in-field recurrences have been experienced. With markedly increased tumor dose, the local control rate can be improved. This treatment method will be an alternative to definitive external radiotherapy to gain better QOL and higher control rate. (author).

Recovery and permanent radiation damage of plastic scintillators at different dose rates

International Nuclear Information System (INIS)

Bicken, B.; Holm, U.; Marckmann, T.; Wick, K.; Rhode, M.

1990-01-01

This paper reports on the radiation stability of plastic scintillators and wavelength shifters for the calorimeter of the ZEUS detector by irradiating them with protons, a 60 Co-source, and depleted uranium. Changes in light yield, absorption length and absorption coefficient have been measured for storage in inert and oxygen atmospheres during and after irradiation. Radiation doses up to 40 kGy with dose rates of 30 up to 2000 Gy/h have been applied. The polystyrene based scintillator SCSN-38 and the wavelength shifters Y-7 and K-27 in PMMA show an additional absorption but a recovery in air to a low permanent damage (at 10 kGy) which is proportional to the applied dose. Series investigations on samples of all production cycles of the ZEUS scintillators with high dose rates show only minor differences in radiation hardness. The recovery is described by a simple oxygen diffusion model for high and medium dose rates down to 30 Gy/h. During long term irradiations at low dose rates (<100 Gy/h) of 3 mm thick SCSN-38 in air the radiation damage recovers to a permanent damage which does not depend on the dose rate. On the other hand the radiation damage at very low dose rates (17 Gy/a) seems to be higher than expected for the accumulated dose

High-dose-rate brachytherapy as salvage modality for locally recurrent prostate cancer after definitive radiotherapy. A systematic review

International Nuclear Information System (INIS)

Chatzikonstantinou, Georgios; Zamboglou, Nikolaos; Roedel, Claus; Tselis, Nikolaos; Zoga, Eleni; Strouthos, Iosif; Butt, Saeed Ahmed

2017-01-01

To review the current status of interstitial high-dose-rate brachytherapy as a salvage modality (sHDR BRT) for locally recurrent prostate cancer after definitive radiotherapy (RT). A literature search was performed in PubMed using ''high-dose-rate, brachytherapy, prostate cancer, salvage'' as search terms. In all, 51 search results published between 2000 and 2016 were identified. Data tables were generated and summary descriptions created. The main outcome parameters used were biochemical control (BC) and toxicity scores. Eleven publications reported clinical outcome and toxicity with follow-up ranging from 4-191 months. A variety of dose and fractionation schedules were described, including 19.0 Gy in 2 fractions up to 42.0 Gy in 6 fractions. The 5-year BC ranged from 18-77%. Late grade 3 genitourinary and gastrointestinal toxicity was 0-32% and 0-5.1%, respectively. sHDR BRT appears as safe and effective salvage modality for the reirradiation of locally recurrent prostate cancer after definitive RT. (orig.) [de

Short vs prolonged dual antiplatelet treatment upon endovascular stenting of peripheral arteries

Directory of Open Access Journals (Sweden)

Kronlage M

2017-10-01

Full Text Available Mariya Kronlage,1 Maximilian Wassmann,1 Britta Vogel,1 Oliver J Müller,1 Erwin Blessing,2 Hugo Katus,1,3 Christian Erbel1 1Department of Cardiology, Angiology and Pneumology, University Hospital Heidelberg, Heidelberg, 2SRH Klinikum Karlsbad Langensteinbach, Karlsbad, 3DZHK German Center for Cardiovascular Research, Partner Site Heidelberg/Mannheim, Mannheim, Germany Introduction: Peripheral artery disease (PAD is a highly prevalent disorder with a substantial economical burden. Dual antiplatelet treatment (DAPT upon endovascular stenting to prevent acute thrombotic reocclusions is an universally accepted practice for postinterventional management of PAD patients. However, the optimal period of time for DAPT upon endovascular stenting is not known.Methods: In the current nonrandomized, retrospective monocentric study, we evaluated the duration of DAPT upon endovascular stenting. A total of 261 endovascular SFA and iliac stenting procedures were performed on 214 patients and these patients were subdivided into a short (4–6 weeks or a prolonged (8–12 weeks DAPT regime group. More than 65% of the patients included were male, approximately 35% were diabetic, and 61% had a history of smoking. Of all the patients, 90% exhibited a Rutherford stage 2–3, and approximately half of the patients had a moderate-to-severe calcified target lesion with a length of >13 cm. Major safety end points were defined as any bleeding, compartment syndrome, and ischemic events. In addition to this, patency, all-cause mortality, as well as amputation were followed up over a period of 12 months upon intervention.Results: Twelve months after endovascular stenting, primary patency in our cohort was comparable between the groups (83.94% short vs 79.8% long DAPT, P>0.05. Major bleeding occurred in 18 cases without any difference between the groups (P>0.05. In addition, during the 12-month follow-up, 6 (3.4% patients in the short and 3 (3.5% in the prolonged DAPT regime

High risk endovascular aneurysm repair: a case report.

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De Silva, Samanthi

2017-10-01

Mr AB is a 66-year old gentleman who presented for elective endovascular aneurysm repair (EVAR) following a routine screening scan identifying a 5.5cm abdominal aortic aneurysm (AAA). He had a past history of chronic obstructive pulmonary disease (COPD) with FEV1/FVC ratio of 48% on pre-assessment. He was hypertensive with a history of ischaemic heart disease (IHD), which has remained asymptomatic following coronary artery bypass grafting (CABG) eight years prior to this presentation. Copyright the Association for Perioperative Practice.

Clinical application of a OneDose MOSFET for skin dose measurements during internal mammary chain irradiation with high dose rate brachytherapy in carcinoma of the breast.

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Kinhikar, Rajesh A; Sharma, Pramod K; Tambe, Chandrashekhar M; Mahantshetty, Umesh M; Sarin, Rajiv; Deshpande, Deepak D; Shrivastava, Shyam K

2006-07-21

In our earlier study, we experimentally evaluated the characteristics of a newly designed metal oxide semiconductor field effect transistor (MOSFET) OneDose in-vivo dosimetry system for Ir-192 (380 keV) energy and the results were compared with thermoluminescent dosimeters (TLDs). We have now extended the same study to the clinical application of this MOSFET as an in-vivo dosimetry system. The MOSFET was used during high dose rate brachytherapy (HDRBT) of internal mammary chain (IMC) irradiation for a carcinoma of the breast. The aim of this study was to measure the skin dose during IMC irradiation with a MOSFET and a TLD and compare it with the calculated dose with a treatment planning system (TPS). The skin dose was measured for ten patients. All the patients' treatment was planned on a PLATO treatment planning system. TLD measurements were performed to compare the accuracy of the measured results from the MOSFET. The mean doses measured with the MOSFET and the TLD were identical (0.5392 Gy, 15.85% of the prescribed dose). The mean dose was overestimated by the TPS and was 0.5923 Gy (17.42% of the prescribed dose). The TPS overestimated the skin dose by 9% as verified by the MOSFET and TLD. The MOSFET provides adequate in-vivo dosimetry for HDRBT. Immediate readout after irradiation, small size, permanent storage of dose and ease of use make the MOSFET a viable alternative for TLDs.

Experimental Platform for Ultra-high Dose Rate FLASH Irradiation of Small Animals Using a Clinical Linear Accelerator

Energy Technology Data Exchange (ETDEWEB)

Schüler, Emil; Trovati, Stefania; King, Gregory; Lartey, Frederick; Rafat, Marjan; Villegas, Manuel; Praxel, A. Joe [Department of Radiation Oncology, Stanford University School of Medicine, Stanford, California (United States); Loo, Billy W., E-mail: BWLoo@stanford.edu [Department of Radiation Oncology, Stanford University School of Medicine, Stanford, California (United States); Stanford Cancer Institute, Stanford University School of Medicine, Stanford, California (United States); Maxim, Peter G., E-mail: PMaxim@stanford.edu [Department of Radiation Oncology, Stanford University School of Medicine, Stanford, California (United States); Stanford Cancer Institute, Stanford University School of Medicine, Stanford, California (United States)

2017-01-01

Purpose: A key factor limiting the effectiveness of radiation therapy is normal tissue toxicity, and recent preclinical data have shown that ultra-high dose rate irradiation (>50 Gy/s, “FLASH”) potentially mitigates this effect. However, research in this field has been strongly limited by the availability of FLASH irradiators suitable for small animal experiments. We present a simple methodologic approach for FLASH electron small animal irradiation with a clinically available linear accelerator (LINAC). Methods and Materials: We investigated the FLASH irradiation potential of a Varian Clinac 21EX in both clinical mode and after tuning of the LINAC. We performed detailed FLUKA Monte Carlo and experimental dosimetric characterization at multiple experimental locations within the LINAC head. Results: Average dose rates of ≤74 Gy/s were achieved in clinical mode, and the dose rate after tuning exceeded 900 Gy/s. We obtained 220 Gy/s at 1-cm depth for a >4-cm field size with 90% homogeneity throughout a 2-cm-thick volume. Conclusions: We present an approach for using a clinical LINAC for FLASH irradiation. We obtained dose rates exceeding 200 Gy/s after simple tuning of the LINAC, with excellent dosimetric properties for small animal experiments. This will allow for increased availability of FLASH irradiation to the general research community.

Experimental Platform for Ultra-high Dose Rate FLASH Irradiation of Small Animals Using a Clinical Linear Accelerator.

Science.gov (United States)

Schüler, Emil; Trovati, Stefania; King, Gregory; Lartey, Frederick; Rafat, Marjan; Villegas, Manuel; Praxel, A Joe; Loo, Billy W; Maxim, Peter G

2017-01-01

A key factor limiting the effectiveness of radiation therapy is normal tissue toxicity, and recent preclinical data have shown that ultra-high dose rate irradiation (>50 Gy/s, "FLASH") potentially mitigates this effect. However, research in this field has been strongly limited by the availability of FLASH irradiators suitable for small animal experiments. We present a simple methodologic approach for FLASH electron small animal irradiation with a clinically available linear accelerator (LINAC). We investigated the FLASH irradiation potential of a Varian Clinac 21EX in both clinical mode and after tuning of the LINAC. We performed detailed FLUKA Monte Carlo and experimental dosimetric characterization at multiple experimental locations within the LINAC head. Average dose rates of ≤74 Gy/s were achieved in clinical mode, and the dose rate after tuning exceeded 900 Gy/s. We obtained 220 Gy/s at 1-cm depth for a >4-cm field size with 90% homogeneity throughout a 2-cm-thick volume. We present an approach for using a clinical LINAC for FLASH irradiation. We obtained dose rates exceeding 200 Gy/s after simple tuning of the LINAC, with excellent dosimetric properties for small animal experiments. This will allow for increased availability of FLASH irradiation to the general research community. Copyright © 2016 Elsevier Inc. All rights reserved.

High-Dose-Rate Brachytherapy Alone for Localized Prostate Cancer in Patients at Moderate or High Risk of Biochemical Recurrence

Energy Technology Data Exchange (ETDEWEB)

Hoskin, Peter [Cancer Centre, Mount Vernon Hospital, Northwood, Middlesex (United Kingdom); Rojas, Ana, E-mail: arc03@btconnect.com [Cancer Centre, Mount Vernon Hospital, Northwood, Middlesex (United Kingdom); Lowe, Gerry; Bryant, Linda; Ostler, Peter; Hughes, Rob; Milner, Jessica; Cladd, Helen [Cancer Centre, Mount Vernon Hospital, Northwood, Middlesex (United Kingdom)

2012-03-15

Purpose: To evaluate genitourinary (GU) and gastrointestinal (GI) morbidity and biochemical control of disease in patients with localized prostate adenocarcinoma treated with escalating doses per fraction of high-dose rate brachytherapy alone. Methods and Materials: A total of 197 patients were treated with 34 Gy in four fractions, 36 Gy in four fractions, 31.5 Gy in three fractions, or 26 Gy in two fractions. Median follow-up times were 60, 54, 36, and 6 months, respectively. Results: Incidence of early Grade {>=} 3 GU morbidity was 3% to 7%, and Grade 4 was 0% to 4%. During the first 12 weeks, the highest mean International Prostate Symptom Score (IPSS) value was 14, and between 6 months and 5 years it was 8. Grade 3 or 4 early GI morbidity was not observed. The 3-year actuarial rate of Grade 3 GU was 3% to 16%, and was 3% to 7% for strictures requiring surgery (4-year rate). An incidence of 1% Grade 3 GI events was seen at 3 years. Late Grade 4 GU or GI events were not observed. At 3 years, 99% of patients with intermediate-risk and 91% with high-risk disease were free of biochemical relapse (log-rank p = 0.02). Conclusions: There was no significant difference in urinary and rectal morbidity between schedules. Biochemical control of disease in patients with intermediate and high risk of relapse was good.

Monte Carlo dosimetric characterization of the Flexisource Co-60 high-dose-rate brachytherapy source using PENELOPE.

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Almansa, Julio F; Guerrero, Rafael; Torres, Javier; Lallena, Antonio M

60 Co sources have been commercialized as an alternative to 192 Ir sources for high-dose-rate (HDR) brachytherapy. One of them is the Flexisource Co-60 HDR source manufactured by Elekta. The only available dosimetric characterization of this source is that of Vijande et al. [J Contemp Brachytherapy 2012; 4:34-44], whose results were not included in the AAPM/ESTRO consensus document. In that work, the dosimetric quantities were calculated as averages of the results obtained with the Geant4 and PENELOPE Monte Carlo (MC) codes, though for other sources, significant differences have been quoted between the values obtained with these two codes. The aim of this work is to perform the dosimetric characterization of the Flexisource Co-60 HDR source using PENELOPE. The MC simulation code PENELOPE (v. 2014) has been used. Following the recommendations of the AAPM/ESTRO report, the radial dose function, the anisotropy function, the air-kerma strength, the dose rate constant, and the absorbed dose rate in water have been calculated. The results we have obtained exceed those of Vijande et al. In particular, the absorbed dose rate constant is ∼0.85% larger. A similar difference is also found in the other dosimetric quantities. The effect of the electrons emitted in the decay of 60 Co, usually neglected in this kind of simulations, is significant up to the distances of 0.25 cm from the source. The systematic and significant differences we have found between PENELOPE results and the average values found by Vijande et al. point out that the dosimetric characterizations carried out with the various MC codes should be provided independently. Copyright © 2017 American Brachytherapy Society. Published by Elsevier Inc. All rights reserved.