The evaluation response of tumours requires quantification of tumour mass in terms of volume or m... more The evaluation response of tumours requires quantification of tumour mass in terms of volume or maximum diameter. In normal practice changes in maximum diameter of tumour are assessed visually on follow-up CT films. This may lead to erroneous results. Twenty one patients of testicular cancer in stage I1 A to I1 D with retroperitoneal lymphadenopathy were scanned by CT for 3 to 5 times during the course of treatment. Tumour size was assessed in terms of diameter as per practice followed routinely. Avery important observation was that actual measurement of diameter instead of visual assessment resulted in change of stage of cancer in 42.8% (9 out of 21) cases. Moreover, in 6 out of these 21 cases (28%) there occurred a change in stage from I1 C to II D which assumes significance due to change in treatment protocol from BEP (Bleomycin. Etoposide, Cisplatinum) to BOP-VIP (Bleomycin, Vincristin, Cisplatinum, VP-16, Ifosfamide, Cisplatinum). Tumour volume estimated on the basis of visual ...
Chemotherapy is a much more complex mode of cancer treatment than radiotherapy, mainly due to the... more Chemotherapy is a much more complex mode of cancer treatment than radiotherapy, mainly due to the variety of drugs available for use that differ among themselves in molecular structure, mode of action, pharmacological properties and side effect. The widely accepted tenets of cancer chemotherapy have been largely arrived at with empiricism. Although a number of models for chemotherapeutic effects have been proposed, most of them had no profound impact on practical clinical situations. Again, generally, they have serious limitations in application due to non-availability of treatment and tumour parameters in human cancers. Nevertheless, they do attempt to provide an insight in intricacies of chemotherapy. This paper presents the underlying scientific basis for cancer chemotherapy and a few models. The paper also proposes a clinically applicable model based upon tumour volume known by CT scan films during chemotherapy protocol of Cisplatinum and Cyclophosphamide in 51 patients of epith...
Medical science monitor : international medical journal of experimental and clinical research, 2003
BACKGROUND Gestational trophoblastic disease (GTD) adversely affects pregnancy by the development... more BACKGROUND Gestational trophoblastic disease (GTD) adversely affects pregnancy by the development of Hydatidiform mole and placental site gestational tumor. GTD is a discrete pool of epidemiological and clinicopathological entities. Therefore, every geographical region should be studied separately. The Indian subcontinent is under-reported for this disease. This paper analyses the data from a large hospital. MATERIAL/METHODS 92 patients with GTD were analyzed in the period from 1995 to 1999. RESULTS The incidence of GTD was 1.31 per 1000 live births and one per 967 pregnancies irrespective of outcome. 93.5% of the patients had moderate to severe vaginal bleeding as presenting symptom, while routine antenatal ultrasonography revealed GTD in 6.5% completely asymptomatic patients. Among the major risk factors were age over 30 (p=6.3 x 10(-3), RR=2.7), previous abortion (p<0.001, RR=3.9) and multigravida (p=4.9 x 10(-6), RR=4.1). Early detection and treatment on established lines can...
Abstract Radiochromic films are one of the most suitable dosimetry tools to perform two-dimension... more Abstract Radiochromic films are one of the most suitable dosimetry tools to perform two-dimensional dose measurement and dose verification in radiotherapy. In this work, a novel polymer based radiochromic film composed of amide substituted diacetylene was developed and its various dosimetric characteristics were investigated. The amide derivative of diacetylene was synthesized and its uniform, bubble-free films were coated on a polyester sheet. A comprehensive evaluation of general dosimetric properties like dose response, energy and dose rate dependence of the developed radiochromic films was carried out. The influence of dose fractionation and post irradiation stability was also examined. The commercially available Gafchromic EBT3 film was taken as the reference and the response of the novel radiochromic films with the change in various parameters was compared with it. The developed radiochromic films exhibited color change from white to blue in the dose range 0-10 Gy. These films showed a dependence of 2.5% on the energy variation and 2% on dose rate variation. A stable response with an average variation of 0.5% was observed between post irradiation times of 1 hour and 3 hours. The influence of change in environmental conditions like storage temperature and light intensity was found to be less than 2.5%. From this study, it can be elucidated that the newly developed radiochromic film renders promising accuracy and versatility which can make it suitable for medical radiation dosimetry.
Narrow band ultraviolet B (NB UVB) radiation doses are administered during phototherapy for vario... more Narrow band ultraviolet B (NB UVB) radiation doses are administered during phototherapy for various dermatological ailments. Precise quantification of these doses is vital because the absorbed irradiation can cause adverse photochemical reactions which can lead to potential phototherapeutic side effects. The paper presents development of diacetylene based dosimeter for the determination of therapeutic NB UVB doses during phototherapy. The amide terminated diacetylene analogues have been synthesized by tailoring them with different functional groups. The synthesized diacetylene monomers have been introduced in a polyvinyl alcohol binder solution to obtain a film dosimeter. The influence of different headgroups on the colorimetric response to UV radiation has been studied. Among all the synthesized diacetylene analogues, the naphthylamine substituted diacetylene exhibited excellent color transition from white to blue color at 100 mJ cm−2 NB UVB radiation dose. The developed amide film...
Abstract In this work urethane substituted diacetylene compound was synthesized to prepare its ra... more Abstract In this work urethane substituted diacetylene compound was synthesized to prepare its radiochromic films which can be sensitive to therapeutic radiation doses. The developed radiochromic films showed significant color change from white to blue in 0–16 Gy dose range. The colorimetric spectral response of the developed films was studied and a maximum absorption at 624 nm was observed which increased with the radiation doses. The change in the morphology of the films pre and post irradiation was analyzed by acquiring their SEM images. The radiation induced color changes were studied quantitatively in terms of optical density by using high resolution Epson scanner along with MATLAB software. The dose response of the developed films was compared with the commercially available Gafchromic EBT3 films. Both the films showed similar dose response with an uncertainty of less than 2%. The post irradiation stability and environmental stability of the films were also analyzed. The films were found to be highly stable under normal environmental conditions with only 1.67% and 1.19% variation in optical density due to the change in temperature and light intensity, respectively. The developed radiochromic films were tissue equivalent and possessed promising characteristics for a potential film dosimeter for medical applications.
Abstract NaMgF3 is a nearly tissue equivalent material with low Zeff = 10.4 and a well-known phos... more Abstract NaMgF3 is a nearly tissue equivalent material with low Zeff = 10.4 and a well-known phosphor for its high sensitivity concerning luminescence. The type of preparation route followed greatly affects the luminescence efficiency of a material. Grinding of NaMgF3:Tb phosphor for a long time induces several lattice defects in the phosphor. In this work, effect of particle size on TL/OSL response of NaMgF3:Tb irradiated by 60Co source of gamma radiations with a dose of 15 Gy has been investigated. NaMgF3:Tb samples has been synthesized by solid state reaction method using different grinding times i.e. 1 h and 5 h. XRD technique confirms its formation and crystallite size is calculated. TL studies show that sample synthesized by 5 h grinding is almost 2 times more intense than the sample obtained by 1 h grinding. Also, a clear enhancement is seen in the shoulder peak of sample grinded for 5 h. This could be due to increase in occupancy of trapped charge carriers in the trap levels. However, the position of main TL glow peak remains same in both the samples. Associated TL kinetic parameters such as order of kinetics, activation energy, frequency factor and trap density have been calculated by deconvoluting the TL glow peaks to understand the TL phenomenon. Continuous-wave optically stimulated luminescence (CW-OSL) decay curves have been obtained under blue LED stimulation for 40 s. Analyzing the CW-OSL decay curves reveal that grinding time significantly affects the OSL intensity of the phosphor as well. The decay constant and photoionization cross-section is determined for the faster and slower components of the total OSL intensity. It could be concluded that the time of grinding taken during preparation of the material has a major role in affecting the concentration of trap levels formed inside the forbidden gap of the phosphor.
Abstract Present study reports the temperature dependent optically stimulated luminescence (TA-OS... more Abstract Present study reports the temperature dependent optically stimulated luminescence (TA-OSL) properties of KCl:Sm in the range of 40–310 °C. KCl:Sm was synthesized by high-temperature solid-state reaction method with optimized dopant concentration of Sm (0.45%). The morphological and structural properties of KCl:Sm are carried out using SEM, and XRD. KCl:Sm is found to be polycrystalline in nature with average crystallite size 30–70 nm as confirmed by XRD. SEM images of KCl:Sm showed the uniform morphology within the range of 0.1 μm. The KCl:Sm exhibits good TA-OSL intensity at 100 °C (at a fixed dose of 10 Gy of gamma photons) as well as the linear response. The optimized elevated temperature for KCl:Sm is found to be 100 °C because of the maximum TA-OSL intensity on this temperature due to the depletion of its filled traps. The Arrhenius analysis estimated the activation energy of Ea, is 0.2 ± 0.05 eV. In this work, we also report thermally stimulated luminescent (TSL) characteristics till 500 °C. Intense and broad TSL peaks are obtained at 265 °C, 310 °C & 340 °C when irradiated to the low energy HCPs protons and carbon beams of 250 keV. In this analysis, the prominent glow peak temperature shifts towards lower temperature region. The trapping kinetic parameters are estimated (for knowing the trap structure) and glow curves are analyzed though de-convolution techniques. The temperature dependence characteristics of KCl:Sm with respect to low LET gamma photons and high LET HCPs have been discussed with reference to medical as well as high radiation dosimetry.
Abstract We investigate the thermoluminescence (TL) properties of nanocrystalline Li2B4O7:Dy. The... more Abstract We investigate the thermoluminescence (TL) properties of nanocrystalline Li2B4O7:Dy. The TL properties of the said phosphor are of great interest as it has an effective atomic number close to that of a biological tissue. The phosphor is synthesized by combustion method and characterized by X-ray diffraction and transmission electron microscopy. When the nanophosphor is exposed to a range of gamma doses using cobalt-60, it exhibits a linear TL response for an extensive range of doses. Further, the reproducibility and batch homogeneity properties are also studied. In conclusion, nanocrystalline Li2B4O7:Dy shows potential as a radiation dosimeter of gamma rays.
Abstract BaSO4:Eu nanophosphor is delicately optimized by varying the concentration of the impuri... more Abstract BaSO4:Eu nanophosphor is delicately optimized by varying the concentration of the impurity element and compared to the commercially available thermoluminescent dosimeter (TLD) LiF:Mg,Ti (TLD-100) and by extension also to CaSO4:Dy (TLD-900) so as to achieve its maximum thermoluminescence (TL) sensitivity. Further, the energy dependence property of this barite nanophosphor is also explored at length by exposing the phosphor with 1.25 MeV of Co-60, 0.662 MeV of Cs-137, 85 MeV and 65 MeV of Carbon ion beams. Various batches of the phosphor at hand (with impurity concentrations being 0.05, 0.10, 0.20, 0.50 and 1.00 mol%) are prepared by the chemical co-precipitation method out of which BaSO4:Eu with 0.20 mol% Eu exhibits the maximum TL sensitivity. Further, the optimized nanophosphor exhibits a whopping 28.52 times higher TL sensitivity than the commercially available TLD-100 and 1.426 times higher sensitivity than TLD-900, a noteworthy linear response curve for an exceptionally wide range of doses i.e. 10 Gy to 2 kGy and a simple glow curve structure. Furthermore, when the newly optimized nanophosphor is exposed with two different energies of gamma radiations, namely 1.25 MeV of Co-60 (dose range- 10–300 Gy) and 0.662 MeV of Cs-137 (dose range- 1–300 Gy), it is observed that the shape and structure of the glow curves remain remarkably similar for different energies of radiation while the TL response curve shows little to no variation. When exposed to different energies of carbon ion beam BaSO4:Eu displays energy independence at lower doses i.e. from 6.059 to 14.497 kGy. Finally, even though energy independence is lost at higher doses, the material shows high sensitivity to higher energy (85 MeV) of carbon beam compared to the lower energy (65 MeV of C6+) and saturation is apparent only after 121.199 kGy. Therefore the present nanophosphor displays potential as an energy independent TLD.
Abstract Calcium Sulfate (CaSO4) is one of the most investigated materials used as Thermally Stim... more Abstract Calcium Sulfate (CaSO4) is one of the most investigated materials used as Thermally Stimulated Luminescence Dosimeter (TLD). It has been experimentally modified with several dopants to increase/modify its Thermoluminescent (TL) sensitivity. Mn (Manganese) doping in CaSO4 being the first to be investigated. CaSO4: Mn inspite of high sensitivity, lost its popularity due to its high fading (40–85% in the first 3 days after exposures). Another potential limitation in the use of this material was its sensitivity to light. We have attempted to turn its limitation to its advantage by discovering its Opticaly Stimulated Luminescence (OSL) properties. Till now no study has been reported in this material for its OSL characteristics. This paper investigates the preliminary studies CaSO4:Mn as a new material for OSL dosimetry. The irradiation was carried out from Sr-90 (beta) and Cs-137 (gamma) sources. Synthesis was carried out by recrystallization method using Calcium sulfate with concentrated sulfuric acid. Formation of the compound was confirmed by the X-ray diffraction (XRD) study. In addition to the study of variation of dose (beta and gamma) on the OSL signal, effect of light induced fading, effect of excitation source, effect of power and time on stimulation signal, effect of thermal and optical annealing have also been examined and reported. The paper also explores the dependence of temperature on the OSL intensity popularly known as Thermally Assisted OSL (TA–OSL) which showed a correlation between the TL and OSL traps. Theoretical analysis of OSL curves for three excitation sources were performed in order to have a deeper understanding of the OSL phenomena. OSL response to a wide range of beta and gamma doses of CaSO4:Mn and excellent reusability confirm its suitability as an effective OSL material and explore its potential for tremendous applications in radiation dosimetry.
Abstract Objective Purpose of the study is to verify the Gamma Knife Extend™ system (ES) based fr... more Abstract Objective Purpose of the study is to verify the Gamma Knife Extend™ system (ES) based fractionated stereotactic radiosurgery with newly developed head-thorax phantom. Methods Phantoms are extensively used to measure radiation dose and verify treatment plan in radiotherapy. A human upper body shaped phantom with thorax was designed to simulate fractionated stereotactic radiosurgery using Extend™ system of Gamma Knife. The central component of the phantom aids in performing radiological precision test, dosimetric evaluation and treatment verification. A hollow right circular cylindrical space of diameter 7.0 cm was created at the centre of this component to place various dosimetric devices using suitable adaptors. The phantom is made of poly methyl methacrylate (PMMA), a transparent thermoplastic material. Two sets of disk assemblies were designed to place dosimetric films in (1) horizontal (xy) and (2) vertical (xz) planes. Specific cylindrical adaptors were designed to place thimble ionization chamber inside phantom for point dose recording along xz axis. EBT3 Gafchromic films were used to analyze and map radiation field. The focal precision test was performed using 4 mm collimator shot in phantom to check radiological accuracy of treatment. The phantom head position within the Extend™ frame was estimated using encoded aperture measurement of repositioning check tool (RCT). For treatment verification, the phantom with inserts for film and ion chamber was scanned in reference treatment position using X-ray computed tomography (CT) machine and acquired stereotactic images were transferred into Leksell Gammaplan (LGP). A patient treatment plan with hypo-fractionated regimen was delivered and identical fractions were compared using EBT3 films and in-house MATLAB codes. Results RCT measurement showed an overall positional accuracy of 0.265 mm (range 0.223 mm–0.343 mm). Gamma index analysis across fractions exhibited close agreement between LGP and film measured dose with ≥90% (max 93%) pixel pass rate at 1 mm of spatial and 1% of dosimetric tolerances. The focal precision test showed the variation of 0.465 mm between radiological and planned iso-centre. Conclusions The study demonstrated the suitability of newly developed head-thorax phantom for dosimetric verification of fractionated stereotactic radiosurgery using Extend™ system of Gamma Knife.
Abstract With the advent of newer techniques for dose reduction coupled with the development of m... more Abstract With the advent of newer techniques for dose reduction coupled with the development of more sensitive detectors, the radiation doses in radiological medical investigation are decreasing. Nevertheless, keeping the tenet in mind that all radiation doses could entail risk, there is a need to develop more sensitive dosimeters capable of measuring low doses. This paper gives the account of the development of a new and sensitive phosphor CaSO 4 :Dy,Mn and its characterization. The standard production procedure based on the recrystallization method was used to prepare CaSO 4 :Dy,Mn. The Thermoluminescence (TL) studies were carried out by exposing it with gamma radiation (Cs-137) from 10 µGy to 100 Gy. The theoretical studies to determine the number of peaks and kinetic parameters related to the TL glow peaks in CaSO 4 :Dy,Mn was performed using the Computerized Glow Curve Deconvolution (CGCD) method. Experiments were performed to determine optimum concentration of the dopants Dysprosium (Dy) and Mangnese (Mn) in the host CaSO 4 so that maximum sensitivity of the phosphor may be achieved. The optimum dopant concentration turned out to be 0.1 mol%. As there were two dopants Dy and Mn their relative ratio were varied in steps of 0.025 keeping the concentration of total dopant (Dy and Mn) 0.1 mol% always. The maximum TL intensity was seen in the CaSO 4 :Dy(0.025),Mn(0.075) combination. The TL sensitivity of this phosphor was found to be about 2 and 1.8 times higher than that of popular phosphor CaSO 4 :Dy and LiF:Mg,Cu,P (TLD-700H) respectively. This new phosphor CaSO 4 :Dy,Mn showed fading of 11% which is similar to that of the standard phosphor CaSO 4 :Dy. The paper concludes that the new, highly sensitive TL phosphor CaSO 4 :Dy,Mn has shown higher sensitivity and hence the potential to replace commonly used CaSO 4 :Dy.
Abstract Nanocrystalline samples of Mn-doped CaF2 were synthesized by chemical coprecipitation me... more Abstract Nanocrystalline samples of Mn-doped CaF2 were synthesized by chemical coprecipitation method. The impurity concentration was varied in the range of 0.5–4.0 mol%. The structure of the synthesized material was confirmed using powder XRD analysis. TEM images of the nanoparticles show their size occurring mostly in the range of 35–40 nm, with clusters of some impurity phases formed on annealing of the material at higher temperatures. Detailed studies on TL showed that the structures of glow curves depend on Mn concentrations and annealing temperatures. Optimization of the concentration and annealing temperature showed that the sample (doped with 3.0 mol% and annealed at 673 K) has almost a single dosimetric glow peak appearing at around 492 K. EPR and PL spectra were further studied to understand the reasons for changes in the glow curve structures. All detailed studies on TL, PL and EPR showed that the changes in glow curve structures are caused not only by the stress connected with the difference in ionic radii of host Ca2+ and the guest impurity Mn3+/Mn2+, but are also governed by other reasons, like diffusion of atmospheric oxygen and formation of impurity aggregates, such as, MnO2, Mn3O4, etc. This is true not only for nanocrystalline CaF2:Mn but could also be so for the bulk CaF2:Mn (TLD-400) and would thus help in understanding complex glow curve structure, high fading and the loss of reusability on annealing beyond 673 K.
This paper investigates the optically stimulated luminescence (OSL) response of BaFCl:Eu and K2Ca... more This paper investigates the optically stimulated luminescence (OSL) response of BaFCl:Eu and K2Ca2(SO4)3:Eu phosphors for different doses and bleaching durations. The results have also been compared with the commercially available Landauer Al2O3:C (Luxel®) dosemeter. Nanocrystalline K2Ca2(SO4)3:Eu is known to be a sensitive thermoluminescent phosphor, but its OSL response is hardly reported. At first, pellets of nanocrystalline K2Ca2(SO4)3:Eu powder were prepared by adding Teflon as a binder. Their OSL signal was compared with that of the material in pure form, i.e. without adding the binder (in 100:1 ratio). It was observed that adding the binder does not appreciably affect the OSL intensity. On comparison with the commercially available Al2O3:C from Landauer, it was found that K2Ca2(SO4)3:Eu is around 15 times less sensitive than Al2O3:C. 'Homemade' BaFCl:Eu phosphor has also been studied. The intensity of BaFCl:Eu was ∼20 times more than the standard Al2O3:C dosemeter and...
ABSTRACT In the present paper optimized dosimetric characteristics of low-Z magnesium tetra-borat... more ABSTRACT In the present paper optimized dosimetric characteristics of low-Z magnesium tetra-borate MgB4O7:Mn,Tb using a thermoluminescence (TL) technique have been reported. The phosphor material was synthesized using a conventional high temperature solid-state diffusion reaction. The crystalline structure and phase purity of synthesized powder were confirmed by powder X-ray diffraction (XRD) analysis. The material in the microcrystalline form was found to be in orthorhombic form. The comparative dosimetric properties of the phosphor material have been extensively investigated for its applications in personal and medical dosimetry. It has been found that the codoped MgB4O7:Mn,Tb material, exposed to γ rays, shows better TL sensitivity and has an edge over the Mn and Tb doped samples as it is much more sensitive than the formers (550 and 40 times, respectively, more than the later ones). It has a simple glow curve structure (two well separated TL peaks centered at around 475 and 650 K). They are sufficiently above the room temperature (RT) to show low fading (~10% in a month after storing in dark at RT). However, the fading is much faster, if exposed to sunlight/room light/UV radiation. This has been a serious problem with many borate based phosphors. A detailed study on bleaching to UV–visible light of different wavelengths (energies) has been carried out and a new mechanism based on redox reactions is proposed. Low fading (~10% in a month) at room temperature on storing in dark, high TL sensitivity (3.5 times than that of TLD-100), tissue equivalence (Zeff≈8.23) and linear dose response up to wide range (0.1 Gy to ~5.0 kGy) of γ rays make it a suitable candidate for the radiation dosimetry and monitoring. However, it needs to be protected from sunlight/room light for fast fading.
Journal of Radioanalytical and Nuclear Chemistry, 2014
ABSTRACT Ce3+-doped NaLi2PO4 orthophosphate (with different impurity concentrations, i.e., 0.01-0... more ABSTRACT Ce3+-doped NaLi2PO4 orthophosphate (with different impurity concentrations, i.e., 0.01-0.3 mol%) was prepared by a solid state reaction method. Formation of the material was confirmed using powder X-ray diffraction analysis. TL intensity was found to be the highest for the material having impurity concentration 0.2 mol% after annealing it at around 600 K for 1 h and subsequently quenching to room temperature. A typical glow curve consists of three peaks at around 454, 493 and 570 K (dosimetry peak). Good sensitivity (similar to 8 times more than that of TLD-100), low fading (similar to 15 % in 2 months), low-Z material (Z (eff) a parts per thousand 10.8), very wide dose response (i.e., 0.1 Gy-1.0 kGy of gamma rays) make the material a &#39;good&#39; thermoluminescent dosimeter (TLD) phosphor suitable for personnel, medical and environmental dosimetry of high-energy radiation using TL. It could also be used during cancer therapy and sterilization of food where high doses are needed to be monitored.
The evaluation response of tumours requires quantification of tumour mass in terms of volume or m... more The evaluation response of tumours requires quantification of tumour mass in terms of volume or maximum diameter. In normal practice changes in maximum diameter of tumour are assessed visually on follow-up CT films. This may lead to erroneous results. Twenty one patients of testicular cancer in stage I1 A to I1 D with retroperitoneal lymphadenopathy were scanned by CT for 3 to 5 times during the course of treatment. Tumour size was assessed in terms of diameter as per practice followed routinely. Avery important observation was that actual measurement of diameter instead of visual assessment resulted in change of stage of cancer in 42.8% (9 out of 21) cases. Moreover, in 6 out of these 21 cases (28%) there occurred a change in stage from I1 C to II D which assumes significance due to change in treatment protocol from BEP (Bleomycin. Etoposide, Cisplatinum) to BOP-VIP (Bleomycin, Vincristin, Cisplatinum, VP-16, Ifosfamide, Cisplatinum). Tumour volume estimated on the basis of visual ...
Chemotherapy is a much more complex mode of cancer treatment than radiotherapy, mainly due to the... more Chemotherapy is a much more complex mode of cancer treatment than radiotherapy, mainly due to the variety of drugs available for use that differ among themselves in molecular structure, mode of action, pharmacological properties and side effect. The widely accepted tenets of cancer chemotherapy have been largely arrived at with empiricism. Although a number of models for chemotherapeutic effects have been proposed, most of them had no profound impact on practical clinical situations. Again, generally, they have serious limitations in application due to non-availability of treatment and tumour parameters in human cancers. Nevertheless, they do attempt to provide an insight in intricacies of chemotherapy. This paper presents the underlying scientific basis for cancer chemotherapy and a few models. The paper also proposes a clinically applicable model based upon tumour volume known by CT scan films during chemotherapy protocol of Cisplatinum and Cyclophosphamide in 51 patients of epith...
Medical science monitor : international medical journal of experimental and clinical research, 2003
BACKGROUND Gestational trophoblastic disease (GTD) adversely affects pregnancy by the development... more BACKGROUND Gestational trophoblastic disease (GTD) adversely affects pregnancy by the development of Hydatidiform mole and placental site gestational tumor. GTD is a discrete pool of epidemiological and clinicopathological entities. Therefore, every geographical region should be studied separately. The Indian subcontinent is under-reported for this disease. This paper analyses the data from a large hospital. MATERIAL/METHODS 92 patients with GTD were analyzed in the period from 1995 to 1999. RESULTS The incidence of GTD was 1.31 per 1000 live births and one per 967 pregnancies irrespective of outcome. 93.5% of the patients had moderate to severe vaginal bleeding as presenting symptom, while routine antenatal ultrasonography revealed GTD in 6.5% completely asymptomatic patients. Among the major risk factors were age over 30 (p=6.3 x 10(-3), RR=2.7), previous abortion (p<0.001, RR=3.9) and multigravida (p=4.9 x 10(-6), RR=4.1). Early detection and treatment on established lines can...
Abstract Radiochromic films are one of the most suitable dosimetry tools to perform two-dimension... more Abstract Radiochromic films are one of the most suitable dosimetry tools to perform two-dimensional dose measurement and dose verification in radiotherapy. In this work, a novel polymer based radiochromic film composed of amide substituted diacetylene was developed and its various dosimetric characteristics were investigated. The amide derivative of diacetylene was synthesized and its uniform, bubble-free films were coated on a polyester sheet. A comprehensive evaluation of general dosimetric properties like dose response, energy and dose rate dependence of the developed radiochromic films was carried out. The influence of dose fractionation and post irradiation stability was also examined. The commercially available Gafchromic EBT3 film was taken as the reference and the response of the novel radiochromic films with the change in various parameters was compared with it. The developed radiochromic films exhibited color change from white to blue in the dose range 0-10 Gy. These films showed a dependence of 2.5% on the energy variation and 2% on dose rate variation. A stable response with an average variation of 0.5% was observed between post irradiation times of 1 hour and 3 hours. The influence of change in environmental conditions like storage temperature and light intensity was found to be less than 2.5%. From this study, it can be elucidated that the newly developed radiochromic film renders promising accuracy and versatility which can make it suitable for medical radiation dosimetry.
Narrow band ultraviolet B (NB UVB) radiation doses are administered during phototherapy for vario... more Narrow band ultraviolet B (NB UVB) radiation doses are administered during phototherapy for various dermatological ailments. Precise quantification of these doses is vital because the absorbed irradiation can cause adverse photochemical reactions which can lead to potential phototherapeutic side effects. The paper presents development of diacetylene based dosimeter for the determination of therapeutic NB UVB doses during phototherapy. The amide terminated diacetylene analogues have been synthesized by tailoring them with different functional groups. The synthesized diacetylene monomers have been introduced in a polyvinyl alcohol binder solution to obtain a film dosimeter. The influence of different headgroups on the colorimetric response to UV radiation has been studied. Among all the synthesized diacetylene analogues, the naphthylamine substituted diacetylene exhibited excellent color transition from white to blue color at 100 mJ cm−2 NB UVB radiation dose. The developed amide film...
Abstract In this work urethane substituted diacetylene compound was synthesized to prepare its ra... more Abstract In this work urethane substituted diacetylene compound was synthesized to prepare its radiochromic films which can be sensitive to therapeutic radiation doses. The developed radiochromic films showed significant color change from white to blue in 0–16 Gy dose range. The colorimetric spectral response of the developed films was studied and a maximum absorption at 624 nm was observed which increased with the radiation doses. The change in the morphology of the films pre and post irradiation was analyzed by acquiring their SEM images. The radiation induced color changes were studied quantitatively in terms of optical density by using high resolution Epson scanner along with MATLAB software. The dose response of the developed films was compared with the commercially available Gafchromic EBT3 films. Both the films showed similar dose response with an uncertainty of less than 2%. The post irradiation stability and environmental stability of the films were also analyzed. The films were found to be highly stable under normal environmental conditions with only 1.67% and 1.19% variation in optical density due to the change in temperature and light intensity, respectively. The developed radiochromic films were tissue equivalent and possessed promising characteristics for a potential film dosimeter for medical applications.
Abstract NaMgF3 is a nearly tissue equivalent material with low Zeff = 10.4 and a well-known phos... more Abstract NaMgF3 is a nearly tissue equivalent material with low Zeff = 10.4 and a well-known phosphor for its high sensitivity concerning luminescence. The type of preparation route followed greatly affects the luminescence efficiency of a material. Grinding of NaMgF3:Tb phosphor for a long time induces several lattice defects in the phosphor. In this work, effect of particle size on TL/OSL response of NaMgF3:Tb irradiated by 60Co source of gamma radiations with a dose of 15 Gy has been investigated. NaMgF3:Tb samples has been synthesized by solid state reaction method using different grinding times i.e. 1 h and 5 h. XRD technique confirms its formation and crystallite size is calculated. TL studies show that sample synthesized by 5 h grinding is almost 2 times more intense than the sample obtained by 1 h grinding. Also, a clear enhancement is seen in the shoulder peak of sample grinded for 5 h. This could be due to increase in occupancy of trapped charge carriers in the trap levels. However, the position of main TL glow peak remains same in both the samples. Associated TL kinetic parameters such as order of kinetics, activation energy, frequency factor and trap density have been calculated by deconvoluting the TL glow peaks to understand the TL phenomenon. Continuous-wave optically stimulated luminescence (CW-OSL) decay curves have been obtained under blue LED stimulation for 40 s. Analyzing the CW-OSL decay curves reveal that grinding time significantly affects the OSL intensity of the phosphor as well. The decay constant and photoionization cross-section is determined for the faster and slower components of the total OSL intensity. It could be concluded that the time of grinding taken during preparation of the material has a major role in affecting the concentration of trap levels formed inside the forbidden gap of the phosphor.
Abstract Present study reports the temperature dependent optically stimulated luminescence (TA-OS... more Abstract Present study reports the temperature dependent optically stimulated luminescence (TA-OSL) properties of KCl:Sm in the range of 40–310 °C. KCl:Sm was synthesized by high-temperature solid-state reaction method with optimized dopant concentration of Sm (0.45%). The morphological and structural properties of KCl:Sm are carried out using SEM, and XRD. KCl:Sm is found to be polycrystalline in nature with average crystallite size 30–70 nm as confirmed by XRD. SEM images of KCl:Sm showed the uniform morphology within the range of 0.1 μm. The KCl:Sm exhibits good TA-OSL intensity at 100 °C (at a fixed dose of 10 Gy of gamma photons) as well as the linear response. The optimized elevated temperature for KCl:Sm is found to be 100 °C because of the maximum TA-OSL intensity on this temperature due to the depletion of its filled traps. The Arrhenius analysis estimated the activation energy of Ea, is 0.2 ± 0.05 eV. In this work, we also report thermally stimulated luminescent (TSL) characteristics till 500 °C. Intense and broad TSL peaks are obtained at 265 °C, 310 °C & 340 °C when irradiated to the low energy HCPs protons and carbon beams of 250 keV. In this analysis, the prominent glow peak temperature shifts towards lower temperature region. The trapping kinetic parameters are estimated (for knowing the trap structure) and glow curves are analyzed though de-convolution techniques. The temperature dependence characteristics of KCl:Sm with respect to low LET gamma photons and high LET HCPs have been discussed with reference to medical as well as high radiation dosimetry.
Abstract We investigate the thermoluminescence (TL) properties of nanocrystalline Li2B4O7:Dy. The... more Abstract We investigate the thermoluminescence (TL) properties of nanocrystalline Li2B4O7:Dy. The TL properties of the said phosphor are of great interest as it has an effective atomic number close to that of a biological tissue. The phosphor is synthesized by combustion method and characterized by X-ray diffraction and transmission electron microscopy. When the nanophosphor is exposed to a range of gamma doses using cobalt-60, it exhibits a linear TL response for an extensive range of doses. Further, the reproducibility and batch homogeneity properties are also studied. In conclusion, nanocrystalline Li2B4O7:Dy shows potential as a radiation dosimeter of gamma rays.
Abstract BaSO4:Eu nanophosphor is delicately optimized by varying the concentration of the impuri... more Abstract BaSO4:Eu nanophosphor is delicately optimized by varying the concentration of the impurity element and compared to the commercially available thermoluminescent dosimeter (TLD) LiF:Mg,Ti (TLD-100) and by extension also to CaSO4:Dy (TLD-900) so as to achieve its maximum thermoluminescence (TL) sensitivity. Further, the energy dependence property of this barite nanophosphor is also explored at length by exposing the phosphor with 1.25 MeV of Co-60, 0.662 MeV of Cs-137, 85 MeV and 65 MeV of Carbon ion beams. Various batches of the phosphor at hand (with impurity concentrations being 0.05, 0.10, 0.20, 0.50 and 1.00 mol%) are prepared by the chemical co-precipitation method out of which BaSO4:Eu with 0.20 mol% Eu exhibits the maximum TL sensitivity. Further, the optimized nanophosphor exhibits a whopping 28.52 times higher TL sensitivity than the commercially available TLD-100 and 1.426 times higher sensitivity than TLD-900, a noteworthy linear response curve for an exceptionally wide range of doses i.e. 10 Gy to 2 kGy and a simple glow curve structure. Furthermore, when the newly optimized nanophosphor is exposed with two different energies of gamma radiations, namely 1.25 MeV of Co-60 (dose range- 10–300 Gy) and 0.662 MeV of Cs-137 (dose range- 1–300 Gy), it is observed that the shape and structure of the glow curves remain remarkably similar for different energies of radiation while the TL response curve shows little to no variation. When exposed to different energies of carbon ion beam BaSO4:Eu displays energy independence at lower doses i.e. from 6.059 to 14.497 kGy. Finally, even though energy independence is lost at higher doses, the material shows high sensitivity to higher energy (85 MeV) of carbon beam compared to the lower energy (65 MeV of C6+) and saturation is apparent only after 121.199 kGy. Therefore the present nanophosphor displays potential as an energy independent TLD.
Abstract Calcium Sulfate (CaSO4) is one of the most investigated materials used as Thermally Stim... more Abstract Calcium Sulfate (CaSO4) is one of the most investigated materials used as Thermally Stimulated Luminescence Dosimeter (TLD). It has been experimentally modified with several dopants to increase/modify its Thermoluminescent (TL) sensitivity. Mn (Manganese) doping in CaSO4 being the first to be investigated. CaSO4: Mn inspite of high sensitivity, lost its popularity due to its high fading (40–85% in the first 3 days after exposures). Another potential limitation in the use of this material was its sensitivity to light. We have attempted to turn its limitation to its advantage by discovering its Opticaly Stimulated Luminescence (OSL) properties. Till now no study has been reported in this material for its OSL characteristics. This paper investigates the preliminary studies CaSO4:Mn as a new material for OSL dosimetry. The irradiation was carried out from Sr-90 (beta) and Cs-137 (gamma) sources. Synthesis was carried out by recrystallization method using Calcium sulfate with concentrated sulfuric acid. Formation of the compound was confirmed by the X-ray diffraction (XRD) study. In addition to the study of variation of dose (beta and gamma) on the OSL signal, effect of light induced fading, effect of excitation source, effect of power and time on stimulation signal, effect of thermal and optical annealing have also been examined and reported. The paper also explores the dependence of temperature on the OSL intensity popularly known as Thermally Assisted OSL (TA–OSL) which showed a correlation between the TL and OSL traps. Theoretical analysis of OSL curves for three excitation sources were performed in order to have a deeper understanding of the OSL phenomena. OSL response to a wide range of beta and gamma doses of CaSO4:Mn and excellent reusability confirm its suitability as an effective OSL material and explore its potential for tremendous applications in radiation dosimetry.
Abstract Objective Purpose of the study is to verify the Gamma Knife Extend™ system (ES) based fr... more Abstract Objective Purpose of the study is to verify the Gamma Knife Extend™ system (ES) based fractionated stereotactic radiosurgery with newly developed head-thorax phantom. Methods Phantoms are extensively used to measure radiation dose and verify treatment plan in radiotherapy. A human upper body shaped phantom with thorax was designed to simulate fractionated stereotactic radiosurgery using Extend™ system of Gamma Knife. The central component of the phantom aids in performing radiological precision test, dosimetric evaluation and treatment verification. A hollow right circular cylindrical space of diameter 7.0 cm was created at the centre of this component to place various dosimetric devices using suitable adaptors. The phantom is made of poly methyl methacrylate (PMMA), a transparent thermoplastic material. Two sets of disk assemblies were designed to place dosimetric films in (1) horizontal (xy) and (2) vertical (xz) planes. Specific cylindrical adaptors were designed to place thimble ionization chamber inside phantom for point dose recording along xz axis. EBT3 Gafchromic films were used to analyze and map radiation field. The focal precision test was performed using 4 mm collimator shot in phantom to check radiological accuracy of treatment. The phantom head position within the Extend™ frame was estimated using encoded aperture measurement of repositioning check tool (RCT). For treatment verification, the phantom with inserts for film and ion chamber was scanned in reference treatment position using X-ray computed tomography (CT) machine and acquired stereotactic images were transferred into Leksell Gammaplan (LGP). A patient treatment plan with hypo-fractionated regimen was delivered and identical fractions were compared using EBT3 films and in-house MATLAB codes. Results RCT measurement showed an overall positional accuracy of 0.265 mm (range 0.223 mm–0.343 mm). Gamma index analysis across fractions exhibited close agreement between LGP and film measured dose with ≥90% (max 93%) pixel pass rate at 1 mm of spatial and 1% of dosimetric tolerances. The focal precision test showed the variation of 0.465 mm between radiological and planned iso-centre. Conclusions The study demonstrated the suitability of newly developed head-thorax phantom for dosimetric verification of fractionated stereotactic radiosurgery using Extend™ system of Gamma Knife.
Abstract With the advent of newer techniques for dose reduction coupled with the development of m... more Abstract With the advent of newer techniques for dose reduction coupled with the development of more sensitive detectors, the radiation doses in radiological medical investigation are decreasing. Nevertheless, keeping the tenet in mind that all radiation doses could entail risk, there is a need to develop more sensitive dosimeters capable of measuring low doses. This paper gives the account of the development of a new and sensitive phosphor CaSO 4 :Dy,Mn and its characterization. The standard production procedure based on the recrystallization method was used to prepare CaSO 4 :Dy,Mn. The Thermoluminescence (TL) studies were carried out by exposing it with gamma radiation (Cs-137) from 10 µGy to 100 Gy. The theoretical studies to determine the number of peaks and kinetic parameters related to the TL glow peaks in CaSO 4 :Dy,Mn was performed using the Computerized Glow Curve Deconvolution (CGCD) method. Experiments were performed to determine optimum concentration of the dopants Dysprosium (Dy) and Mangnese (Mn) in the host CaSO 4 so that maximum sensitivity of the phosphor may be achieved. The optimum dopant concentration turned out to be 0.1 mol%. As there were two dopants Dy and Mn their relative ratio were varied in steps of 0.025 keeping the concentration of total dopant (Dy and Mn) 0.1 mol% always. The maximum TL intensity was seen in the CaSO 4 :Dy(0.025),Mn(0.075) combination. The TL sensitivity of this phosphor was found to be about 2 and 1.8 times higher than that of popular phosphor CaSO 4 :Dy and LiF:Mg,Cu,P (TLD-700H) respectively. This new phosphor CaSO 4 :Dy,Mn showed fading of 11% which is similar to that of the standard phosphor CaSO 4 :Dy. The paper concludes that the new, highly sensitive TL phosphor CaSO 4 :Dy,Mn has shown higher sensitivity and hence the potential to replace commonly used CaSO 4 :Dy.
Abstract Nanocrystalline samples of Mn-doped CaF2 were synthesized by chemical coprecipitation me... more Abstract Nanocrystalline samples of Mn-doped CaF2 were synthesized by chemical coprecipitation method. The impurity concentration was varied in the range of 0.5–4.0 mol%. The structure of the synthesized material was confirmed using powder XRD analysis. TEM images of the nanoparticles show their size occurring mostly in the range of 35–40 nm, with clusters of some impurity phases formed on annealing of the material at higher temperatures. Detailed studies on TL showed that the structures of glow curves depend on Mn concentrations and annealing temperatures. Optimization of the concentration and annealing temperature showed that the sample (doped with 3.0 mol% and annealed at 673 K) has almost a single dosimetric glow peak appearing at around 492 K. EPR and PL spectra were further studied to understand the reasons for changes in the glow curve structures. All detailed studies on TL, PL and EPR showed that the changes in glow curve structures are caused not only by the stress connected with the difference in ionic radii of host Ca2+ and the guest impurity Mn3+/Mn2+, but are also governed by other reasons, like diffusion of atmospheric oxygen and formation of impurity aggregates, such as, MnO2, Mn3O4, etc. This is true not only for nanocrystalline CaF2:Mn but could also be so for the bulk CaF2:Mn (TLD-400) and would thus help in understanding complex glow curve structure, high fading and the loss of reusability on annealing beyond 673 K.
This paper investigates the optically stimulated luminescence (OSL) response of BaFCl:Eu and K2Ca... more This paper investigates the optically stimulated luminescence (OSL) response of BaFCl:Eu and K2Ca2(SO4)3:Eu phosphors for different doses and bleaching durations. The results have also been compared with the commercially available Landauer Al2O3:C (Luxel®) dosemeter. Nanocrystalline K2Ca2(SO4)3:Eu is known to be a sensitive thermoluminescent phosphor, but its OSL response is hardly reported. At first, pellets of nanocrystalline K2Ca2(SO4)3:Eu powder were prepared by adding Teflon as a binder. Their OSL signal was compared with that of the material in pure form, i.e. without adding the binder (in 100:1 ratio). It was observed that adding the binder does not appreciably affect the OSL intensity. On comparison with the commercially available Al2O3:C from Landauer, it was found that K2Ca2(SO4)3:Eu is around 15 times less sensitive than Al2O3:C. 'Homemade' BaFCl:Eu phosphor has also been studied. The intensity of BaFCl:Eu was ∼20 times more than the standard Al2O3:C dosemeter and...
ABSTRACT In the present paper optimized dosimetric characteristics of low-Z magnesium tetra-borat... more ABSTRACT In the present paper optimized dosimetric characteristics of low-Z magnesium tetra-borate MgB4O7:Mn,Tb using a thermoluminescence (TL) technique have been reported. The phosphor material was synthesized using a conventional high temperature solid-state diffusion reaction. The crystalline structure and phase purity of synthesized powder were confirmed by powder X-ray diffraction (XRD) analysis. The material in the microcrystalline form was found to be in orthorhombic form. The comparative dosimetric properties of the phosphor material have been extensively investigated for its applications in personal and medical dosimetry. It has been found that the codoped MgB4O7:Mn,Tb material, exposed to γ rays, shows better TL sensitivity and has an edge over the Mn and Tb doped samples as it is much more sensitive than the formers (550 and 40 times, respectively, more than the later ones). It has a simple glow curve structure (two well separated TL peaks centered at around 475 and 650 K). They are sufficiently above the room temperature (RT) to show low fading (~10% in a month after storing in dark at RT). However, the fading is much faster, if exposed to sunlight/room light/UV radiation. This has been a serious problem with many borate based phosphors. A detailed study on bleaching to UV–visible light of different wavelengths (energies) has been carried out and a new mechanism based on redox reactions is proposed. Low fading (~10% in a month) at room temperature on storing in dark, high TL sensitivity (3.5 times than that of TLD-100), tissue equivalence (Zeff≈8.23) and linear dose response up to wide range (0.1 Gy to ~5.0 kGy) of γ rays make it a suitable candidate for the radiation dosimetry and monitoring. However, it needs to be protected from sunlight/room light for fast fading.
Journal of Radioanalytical and Nuclear Chemistry, 2014
ABSTRACT Ce3+-doped NaLi2PO4 orthophosphate (with different impurity concentrations, i.e., 0.01-0... more ABSTRACT Ce3+-doped NaLi2PO4 orthophosphate (with different impurity concentrations, i.e., 0.01-0.3 mol%) was prepared by a solid state reaction method. Formation of the material was confirmed using powder X-ray diffraction analysis. TL intensity was found to be the highest for the material having impurity concentration 0.2 mol% after annealing it at around 600 K for 1 h and subsequently quenching to room temperature. A typical glow curve consists of three peaks at around 454, 493 and 570 K (dosimetry peak). Good sensitivity (similar to 8 times more than that of TLD-100), low fading (similar to 15 % in 2 months), low-Z material (Z (eff) a parts per thousand 10.8), very wide dose response (i.e., 0.1 Gy-1.0 kGy of gamma rays) make the material a &#39;good&#39; thermoluminescent dosimeter (TLD) phosphor suitable for personnel, medical and environmental dosimetry of high-energy radiation using TL. It could also be used during cancer therapy and sterilization of food where high doses are needed to be monitored.
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Papers by Pratik Kumar