Optical evaluation of dithizone solution as a new radiochromic dosimeter

2020 ◽  
Vol 49 (4) ◽  
pp. 249-253 ◽  
Author(s):  
Khalid Rabaeh ◽  
Ahmed Basfar
Keyword(s):  
Free Radicals ◽  
Region Of Interest ◽  
Food Irradiation ◽  
Optical Measurements ◽  
High Dose ◽  
Radiation Processing ◽  
Content Type ◽  
Radiochromic Dosimeter ◽  
Practical Implications ◽  
Dose Radiation

Purpose The purpose of this paper is to propose a new dithizone solution dosimeter for high radiation applications such as polymers applications and food irradiation. Design/methodology/approach Gamma-rays cell of Co-60 source with 8.4 kGy/h dose rate was used to irradiate the dithizone solutions at different irradiation temperatures. The optical measurements of unirradiated and irradiated dithizone dye solution dosimeters were performed using a UV/VIS spectrophotometer at absorption peaks of 421 and 515 nm. Findings The new dosimeter improved significantly with the increase of dithizone dye concentrations from 0.025 to 0.1 mM. The dosimeter shows a perfect pre- and post-irradiation stability after irradiation for five days. Because of irradiation temperature dependence, the dithizone solution dosimeter should be corrected under actual processing conditions. Practical implications Dosimetry is a key point in quality control of radiation processing to assure that uniform and correct radiation doses are delivered to a region of interest. Therefore, this study introduces a dithizone solution dosimeter for high-dose radiation applications such as food irradiation, polymers applications and agriculture. Originality/value Ionizing radiation interacted with the ethanol solvent, resulting in the formation of free radicals, then these free radicals interacted with the dithizone molecule and changed the dye color from yellow to orange.

Dosimetric evaluation of methyl red radiochromic film for radiation processing

2020 ◽  
Vol ahead-of-print (ahead-of-print) ◽  
Author(s):  
Awad AL Zahrany ◽  
Khalid Rabaeh ◽  
Molham Eyadeh ◽  
Ahmed Basfar
Keyword(s):  
Gamma Ray ◽  
Dose Range ◽  
Absorbed Dose ◽  
Radiochromic Film ◽  
High Dose ◽  
Methyl Red ◽  
Radiation Processing ◽  
Content Type ◽  
The Stability ◽  
The Impact

Purpose The purpose of this paper is to present a radiochromic film dosimeter containing polyvinyl alcohol (PVA) matrix and various concentrations of methyl red (MR) dye for high dose measurements. Design/methodology/approach The MR-PVA films were exposed to irradiation up to 60 kGy using 60Co source of gamma ray. The ultraviolet and visible regions (UV/VIS) spectrophotometry were used to examine the optical density of pre-and post-irradiated dosimeters at 424 nm. Findings The dose sensitivity of MR-PVA films increases significantly with increasing MR dye concentrations in the dose range of 5 to 60 kGy. The impact of relative humidity, irradiation temperature, dose rate and the stability of the films has been analyzed. The overall uncertainty of the MR-PVA film dosimeter is 6.12% (Double Standard-deviation, 95% confidence level). Practical implications It was found that the MR-PVA films may be used as high dose dosimeter with an acceptable overall uncertainty in routine industrial radiation processing. Originality/value The color bleaching of irradiated MR-PVA films in terms of specific absorbance curves increases significantly with increasing absorbed dose up to 60 kGy.

Radiation therapy in the management of low-grade supratentorial astrocytomas

1989 ◽  
Vol 70 (6) ◽  
pp. 853-861 ◽  
Author(s):  
Edward G. Shaw ◽  
Catherine Daumas-Duport ◽  
Bernd W. Scheithauer ◽  
David T. Gilbertson ◽  
Judith R. O'Fallon ◽  
...  
Keyword(s):  
Low Dose ◽  
Survival Rates ◽  
High Dose ◽  
Survival Times ◽  
Low Dose Radiation ◽  
Tumor Removal ◽  
Content Type ◽  
Pilocytic Astrocytomas ◽  
Dose Radiation ◽  
Fine Print

✓ The records of 167 patients with grade 1 or 2 supratentorial pilocytic astrocytomas (41 patients), ordinary astrocytomas (91 patients), or mixed oligoastrocytomas (35 patients) diagnosed between 1960 and 1982 are retrospectively reviewed. The extent of surgical tumor removal was gross total or radical subtotal in 33 patients (20%) and subtotal or biopsy only in the remaining 134 patients (80%). Postoperative radiation therapy was given to 139 (83%) of the 167 patients, with a median dose of 5000 cGy (range 600 to 6500 cGy). Multivariate analysis revealed that a pilocytic histology was the most significant prognostic variable associated with a good survival. The 5- and 10-year survival rates were, respectively, 85% and 79% for the 41 patients with pilocytic astrocytomas compared to 51% and 23% for the 126 patients with ordinary astrocytomas or mixed oligoastrocytomas. Postoperative irradiation did not appear to be associated with improved survival times in the patients with pilocytic astrocytomas; however, in the 126 patients with ordinary astrocytomas or mixed oligoastrocytomas, those who received “high-dose” radiation (≥ 5300 cGy) had significantly better survival times than those who received “low-dose” radiation (< 5300 cGy) or surgery alone. The 5- and 10-year survival rates were, respectively, 68% and 39% for the 35 patients receiving high-dose radiation, 47% and 21% for the 67 receiving low-dose radiation, and 32% and 11% for the 19 treated with surgery alone. The survival rate was poor for the 23 patients with ordinary astrocytomas and oligoastrocytomas who underwent gross total or radical subtotal tumor removal (14 of whom were also irradiated): 52% at 5 years and 21% at 10 years, with 19 of 23 patients developing tumor progression and dying 1 to 12 years postoperatively. In contrast, all 10 patients with pilocytic astrocytomas who had gross total or radical subtotal tumor removal alone were long-term survivors, with follow-up periods of about 4 to 25 years.

Detection of recurrent gliomas with quantitative thallium-201/technetium-99m HMPAO single-photon emission computerized tomography

1992 ◽  
Vol 77 (4) ◽  
pp. 565-570 ◽  
Author(s):  
Paulo A. Carvalho ◽  
Richard B. Schwartz ◽  
Eben Alexander ◽  
Basem M. Garada ◽  
Robert E. Zimmerman ◽  
...  
Keyword(s):  
Radiation Therapy ◽  
Tumor Recurrence ◽  
Single Photon ◽  
Photon Emission ◽  
High Dose ◽  
Recurrent Tumor ◽  
Single Photon Emission ◽  
Content Type ◽  
Hmpao Spect ◽  
Dose Radiation

✓ Deteriorating clinical status after high-dose radiation therapy for high-grade gliomas may be due to radiation changes or may signal recurrent or residual tumor mass. The two conditions cannot be distinguished reliably by computerized tomography (CT) or magnetic resonance (MR) imaging. The authors assessed the ability of sequential thallium-201 chloride (201T1) and technetium-99m hexamethylpropylene amine oxime (99mTc HMPAO) single-photon emission CT (SPECT) to distinguish tumor recurrence from radiation changes after high-dose (≥ 600 cGy) radiation therapy for malignant gliomas. Preoperative tumor/nontumor uptake ratios were analyzed in 32 patients and correlated with the presence of gross tumor at the time of reoperation. In 12 of 13 patients with 201T1 tumor/scalp ratios of 3.5 or greater, recurrent tumor was present. The authors found 99mTc HMPAO SPECT to be useful for identifying the absence of solid tumor recurrence in patients with low to moderate 201T1 uptake (ratio 1.1 to 3.4) and low perfusion to that site. In 11 of 12 patients with 99mTc HMPAO tumor/cerebellum ratios of 0.50 or less, no recurrent tumor mass was present. Three of seven patients with 201T1 ratios of 3.4 or less and 99mTc HMPAO ratios of 0.51 or more had recurrent tumor found at surgery; thus the test was not predictive in this group. It is concluded that the use of sequential 201T1 and 99mTc HMPAO SPECT accurately identifies the presence of tumor recurrence versus radiation changes in most patients with high-grade astrocytomas who have undergone tumor resection and high-dose radiation therapy.

scholarly journals Preparation of New ESR Dosimetry System for High Dose Radiation Processing

2020 ◽  
Vol 63 (4) ◽  
pp. 9-10
Author(s):  
essam faheem ◽  
shadia moniem ◽  
mohamoud el Ahdal
Keyword(s):  
High Dose ◽  
Radiation Processing ◽  
Dosimetry System ◽  
Dose Radiation

Meningiomas induced by high-dose cranial irradiation

1993 ◽  
Vol 79 (1) ◽  
pp. 28-31 ◽  
Author(s):  
Ellen E. Mack ◽  
Charles B. Wilson
Keyword(s):  
Radiation Therapy ◽  
Tinea Capitis ◽  
Previous History ◽  
Cranial Irradiation ◽  
Primary Brain Tumor ◽  
High Dose ◽  
Low Doses ◽  
Content Type ◽  
History Of ◽  
Dose Radiation

✓ Although meningiomas are known to be induced by low doses of cranial irradiation, such as those given to treat tinea capitis, little experience has been reported on the induction of meningiomas by high-dose cranial irradiation. The authors describe a series of 10 patients with meningiomas and a previous history of high-dose radiation therapy, usually given for a primary brain tumor. Of the 10 patients, eight were female, three had multiple meningiomas, and the majority had other stigmata of previous radiation therapy. Eight meningiomas were examined pathologically and one-half were classified as either aggressive or atypical, or were noted to have a high bromodeoxyuridine labeling index. The average time from radiation therapy to diagnosis of a meningioma was 24 years (range 5 to 40 years), a shorter interval than that previously reported for meningiomas induced by lower doses of irradiation. Within this series, patient age at irradiation was significantly correlated with tumor latency; individuals who were younger at the time of radiation therapy had a shorter time to meningioma formation. The latency of meningioma formation is therefore influenced by both the radiation dose and the age of the patient at irradiation.

Radiation-induced meningioma with a 63-year latency period

1995 ◽  
Vol 82 (3) ◽  
pp. 487-488 ◽  
Author(s):  
Bette K. Kleinschmidt-DeMasters ◽  
Kevin O. Lillehei
Keyword(s):  
Inverse Relationship ◽  
Latency Period ◽  
Tumor Formation ◽  
High Dose ◽  
Time Interval ◽  
Cerebellar Tumor ◽  
Content Type ◽  
Radiation Induced ◽  
Orthovoltage Radiotherapy ◽  
Dose Radiation

✓ Meningiomas are known to be induced by low-, moderate-, and high-dose radiation therapy, with an average time interval to tumor appearance of 35, 26, and 19 to 24 years, respectively. An inverse relationship is suggested between the dose of radiation given and the time to tumor formation. The authors report a case of a 68-year-old woman who received orthovoltage radiotherapy at 5 years of age for a presumed (nonbiopsy confirmed) right cerebellar tumor and developed multiple meningiomas in the radiation portals 63 years later. Like many radiation-induced meningiomas, the tumor was histologically atypical and multiple in its presentation. This case suggests that previous radiotherapy may confer a low, but life-long, risk for meningioma occurrence.

Dual-isotope single-photon emission computerized tomography scanning in patients with glioblastoma multiforme: association with patient survival and histopathological characteristics of tumor after high-dose radiotherapy

1998 ◽  
Vol 89 (1) ◽  
pp. 60-68 ◽  
Author(s):  
Richard B. Schwartz ◽  
B. Leonard Holman ◽  
Joseph F. Polak ◽  
Basem M. Garada ◽  
Marc S. Schwartz ◽  
...  
Keyword(s):  
Survival Rate ◽  
Glioblastoma Multiforme ◽  
Single Photon ◽  
Photon Emission ◽  
High Dose ◽  
Term Survival ◽  
Content Type ◽  
Dual Isotope ◽  
Fine Print

Object. The study was conducted to determine the association between dual-isotope single-photon emission computerized tomography (SPECT) scanning and histopathological findings of tumor recurrence and survival in patients treated with high-dose radiotherapy for glioblastoma multiforme. Methods. Studies in which SPECT with 201Tl and 99mTc-hexamethypropyleneamine oxime (HMPAO) were used were performed 1 day before reoperation in 47 patients with glioblastoma multiforme who had previously been treated by surgery and high-dose radiotherapy. Maximum uptake of 201Tl in the lesion was expressed as a ratio to that in the contralateral scalp, and uptake of 99mTc-HMPAO was expressed as a ratio to that in the cerebellar cortex. Patients were stratified into groups based on the maximum radioisotope uptake values in their tumor beds. The significance of differences in patient gender, histological characteristics of tissue at reoperation, and SPECT uptake group with respect to 1-year survival was elucidated by using the chi-square statistic. Comparisons of patient ages and time to tumor recurrence as functions of 1-year survival were made using the t-test. Survival data at 1 year were presented according to the Kaplan—Meier method, and the significance of potential differences was evaluated using the log-rank method. The effects of different variables (tumor type, time to recurrence, and SPECT grouping) on long-term survival were evaluated using Cox proportional models that controlled for age and gender. All patients in Group I (201Tl ratio < 2 and 99mTc-HMPAO ratio < 0.5) showed radiation changes in their biopsy specimens: they had an 83.3% 1-year survival rate. Group II patients (201T1 ratio < 2 and 99mTc-HMPAO ratio of ≥ 0.5 or 201Tl ratio between 2 and 3.5 regardless of 99mTc-HMPAO ratio) had predominantly infiltrating tumor (66.6%); they had a 29.2% 1-year survival rate. Almost all of the patients in Group III (201Tl ratio > 3.5 and 99mTc-HMPAO ratio ≥ 0.5) had solid tumor (88.2%) and they had a 6.7% 1-year survival rate. Histological data were associated with 1-year survival (p < 0.01); however, SPECT grouping was more closely associated with 1-year survival (p < 0.001) and was the only variable significantly associated with long-term survival (p < 0.005). Conclusions. Dual-isotope SPECT data correlate with histopathological findings made at reoperation and with survival in patients with malignant gliomas after surgical and high-dose radiation therapy.

Gamma knife radiosurgery in patients with advanced breast cancer undergoing bone marrow transplant

2002 ◽  
Vol 97 ◽  
pp. 663-665 ◽  
Author(s):  
Kenneth J. Levin ◽  
Emad F. Youssef ◽  
Andrew E. Sloan ◽  
Rajiv Patel ◽  
Rana K. Zabad ◽  
...  
Keyword(s):  
Breast Cancer ◽  
Advanced Breast Cancer ◽  
Gamma Knife ◽  
Gamma Knife Radiosurgery ◽  
High Dose Chemotherapy ◽  
Advanced Breast ◽  
High Dose ◽  
Initial Management ◽  
Content Type ◽  
Fine Print

Object. Recent studies have suggested a high incidence of cognitive deficits in patients undergoing high-dose chemotherapy, which appears to be dose related. Whole-brain radiotherapy (WBRT) has previously been associated with cognitive impairment. The authors attempted to use gamma knife radiosurgery (GKS) to delay or avoid WBRT in patients with advanced breast cancer treated with high-dose chemotherapy and autologous bone marrow transplantation (HDC/ABMT) in whom brain metastases were diagnosed. Methods. A retrospective review of our experience from 1996 to 2001 was performed to identify patients who underwent HDC/ABMT for advanced breast cancer and brain metastasis. They were able to conduct GKS as initial management to avoid or delay WBRT in 12 patients following HDC/ABMT. All patients were women. The median age was 48 years (range 30–58 years). The Karnofsky Performance Scale score was 70 (range 60–90). All lesions were treated with a median prescription dose of 17 Gy (range 15–18 Gy) prescribed to the 50% isodose. Median survival was 11.5 months. Five patients (42%) had no evidence of central nervous system disease progression and no further treatment was given. Four patients were retreated with GKS and three of them eventually received WBRT as well. Two patients were treated with WBRT as the primary salvage therapy. The median time to retreatment with WBRT was 8 months after the initial GKS. Conclusions. Gamma knife radiosurgery can be effectively used for the initial management of brain metastases to avoid or delay WBRT in patients treated previously with HDC, with acceptable survival and preserved cognitive function.

Consumer value creation through WhatsApp use

2019 ◽  
Vol 32 (4) ◽  
pp. 455-471
Author(s):  
Jorge Cruz-Cárdenas ◽  
Jorge Guadalupe-Lanas ◽  
Ekaterina Zabelina ◽  
Andrés Palacio-Fierro ◽  
Margarita Velín-Fárez ◽  
...  
Keyword(s):  
Latin American ◽  
Value Creation ◽  
Emotional Support ◽  
Design Methodology ◽  
Instant Messaging ◽  
Role Performance ◽  
Content Type ◽  
Consumer Value ◽  
Depth Interviews ◽  
Practical Implications

Purpose The purpose of this paper is to understand in-depth how consumers create value in their lives using WhatsApp, the leading mobile instant messaging (MIM) application. Design/methodology/approach The study adopts the perspective of customer-dominant logic (CDL) and uses a qualitative multimethod design involving 3 focus groups and 25 subsequent in-depth interviews. The research setting was Ecuador, a Latin American country. Findings Analysis and interpretation of the participants’ stories made it possible to identify and understand the creation of four types of value: maintaining and strengthening relationships; improving role performance; emotional support; and entertainment and fun. In addition, the present study proposes a conceptual model of consumer value creation as it applies to MIM. Practical implications Understanding the way consumers create value in their lives using MIM is important not only for organizations that offer MIM applications, but also for those companies that develop other applications for mobile phones or for those who wish to use MIM as an electronic word-of-mouth vehicle. Originality/value The current study is one of the first to address the topic of consumer behavior in the use of technologies from the perspective of CDL; this perspective enables an integrated qualitative vision of value creation in which the consumer is the protagonist.

Sign in / Sign up

Export Citation Format

Share Document