Evaluation of kV-CBCT based 3D dose calculation accuracy and its validation using delivery fluence derived dose metrics in Head and Neck Cancer

PURPOSE

The purpose of this study is to evaluate the dosimetric impact of Hounsfield unit (HU) variations in kilovoltage cone-beam computed tomography (kV-CBCT) based 3D dose calculation accuracy in the treatment planning system and its validation using measured treatment delivery dose (MTDD) derived dose metrics for Volumetric Modulated Arc Therapy (VMAT) and Intensity Modulated Radiotherapy (IMRT) plans in Head and Neck (HN) Cancer.

METHODS

CBCT dose calculation accuracy was evaluated for 8 VMAT plans on inhomogeneous phantom and 40 VMAT and IMRT plans of HN Cancer patients and validated using ArcCHECK diode array MTDD derived 3D dose metric on CT and CBCT.

RESULTS

The mean percentage dose difference between CBCT and CT in TPS (ΔD(CBCT-CT)_TPS) and 3DVH (ΔD(CBCT-CT)_3DVH) were compared for the corresponding evaluation dose metrics (D_98%, D_95%, D_50%, D_2%, D_max, D_1cc, D_0.03cc, D_mean) of all PTVs and OARs in phantom and patients. ΔD(CBCT-CT)_TPS and ΔD(CBCT-CT)_3DVH for all evaluation dose points of all PTVs and OARs were less than 2.55% in phantom and 2.4% in HN patients. The Pearson correlation coefficient (r) between ΔD(CBCT-CT)_TPS and ΔD(CBCT-CT)_3DVH for all dose points in all PTVs and OARs showed a strong to moderate correlation in phantom and patients with p < 0.001.

CONCLUSIONS

This study evaluated and validated the potential feasibility of kV-CBCT for treatment plan 3D dose reconstruction in clinical decision making for Adaptive radiotherapy on CT in Head and Neck cancer.

Solid state diffusion and amalgamating anionic exchange at a KNaSO4 phosphors activated with Eu3+ , Dy3+ and Sm3+ rare earth ions to enhance w-LED performance

In present work, KNa(SO₄ ) phosphors doped with different concentrations of rare earth Eu³⁺ , Sm³⁺ and Dy³⁺ ions (0.05, 0.1, 0.3, 0.5, 0.7, 1 mol%) were synthesized using a solid-state diffusion technique. Photoluminescence (PL) investigations were carried out for the whole range of Eu³⁺ , Sm³⁺ and Dy³⁺ -doped phosphors; rare earth ions that retained maximum PL intensity were selected for advanced anionic exchange. In the present investigation, phosphors KNa(SO₄ ):Eu³⁺ (1 mol%), KNa(SO₄ ):Dy^3 +  (0.5 mol%) and KNa(SO₄ ):Sm³⁺ (0.3 mol%) had the highest PL intensity, and were therefore selected for further anionic substitution of sulphate anions with different concentrations of vanadate, phosphate, and tungstate anions, such as KNa(SO₄ )_1-x (MO₄ )_x : W (where W = Eu³⁺ 1 mol%, Dy³⁺ 0.5 mol% and Sm³⁺ 0.3 mol%; MO₄  = PO₄ , VO₄ , WO₄ ; and x = 0.1, 0.3, 0.5, 0.7, 1). Structural and molecular environments of the substituted phosphors were characterized individually using X-ray diffraction and Fourier transform infrared spectroscopy. In-depth morphological investigations of the prepared phosphors were undertaken using scanning electron microscopy. For the principal investigation on enhancement of white light-emitting diode (w-LED) performance, the PL properties of all the synthesized phosphors were studied analytically. Emission intensity ratios for KNa(SO₄ ):Eu³⁺ 1 mol%, KNa(SO₄ )₀ (PO₄ )₁ :Eu 1 mol%, KNa(SO₄ )_0.9 (VO₄ )₁ :Eu 1 mol%, and KNa(SO₄ )_0.9 (WO₄ )_0.1 :Eu 1 mol% were 1:1.15:1.23:0.08. PL intensity ratios for the phosphors KNaSO₄ :Dy 0.5 mol% and KNa(SO₄ )_0.9 (PO₄ )0.1:Dy 0.5 mol% was 1:2. The ratio of PL intensity was 1:3.2:0.8 for KNa(SO₄ ):Sm 1 mol%, KNa(SO₄ )_0.5 (PO4)_0.5 :Sm 0.3 mol%, and KNa(SO₄ )_0.7 (VO₄ )_0.3 :Sm 0.3 mol% phosphors, respectively. Chromaticity investigations were carried out using Commission Internationale de l'Éclairage colour co-ordinate diagrams, which suggested that the prepared Eu³⁺ -doped and Sm³⁺ -doped phosphors would be prospective candidates for red and green LEDs, respectively, whereas Dy³⁺ -doped phosphors showed emission in the blue and yellow regions. The entire study indicated that amalgamation of anionic exchange at a KNaSO⁴ phosphor activated with Eu³⁺ , Dy³⁺ and Sm³⁺ rare earth ions could generate and enhance white light emission.

Short review on recent progress in Mn4+ -activated oxide phosphors for indoor plant light-emitting diodes

In the modern era, growing number of indoor plants for various purposes, such as vegetation, flowering, and decorations, has increased over the traditional follow-up trends for plantation. However, the indoor plantation requires different parameters for their growth; among these, light plays a significant role. In order to control the growth of plants using light-emitting diodes, Mn-doped oxide phosphors have emerged as promising candidates due to their broad and intense emission bands in the red and far-red spectral range. In this review article, recent progress on Mn-doped oxides for indoor plant growth has been reviewed. This review article is mainly divided into three parts. In the first part, different reaction conditions for the synthesis of Mn-doped oxide phosphors are compared. In the second part, the luminescent and other photometric parameters of these are discussed. The influence of different co-dopants on the luminescent characteristics has been elucidated in detail. The third part discusses the properties of light-emitting diodes fabricated using these phosphors for plant growth. The present review article elucidates the synthesis parameters, luminescent properties, and light-emitting diodes fabricated using Mn-doped oxide materials for plant growth applications.

Thermoluminescence study in fossils of dinosaur bones and eggshells

In this study, thermoluminescence (TL) characterization of fossils of sauropod dinosaur bone, dinosaur eggshells, and associated sediments were recorded for the first time. The fossil bone was collected from the Bagwanya intertrappean sediments in the Dhar district of Madhya Pradesh, India. TL was recorded using ⁶⁰ Co gamma ray exposure at different doses. Fossils of dinosaur bone, dinosaur eggshells, and associated sediments were irradiated using ⁶⁰ Co gamma rays at different doses from 0.15 kGy to 19 kGy. The linear dose-response curve of the irradiated sample was obtained for a dose ranging from 0.15 kGy to 9.5 kGy. These geological samples were characterized further using X-ray diffraction for confirmation with phase, scanning electron microscopy, Fourier transform infrared spectroscopy, and wavelength dispersive-X-ray fluorescence for determination of the elemental composition in parts per million to percentage levels.

Thermoluminescence dosimetry properties and kinetic analysis of K3 Ca2 (SO4 )3 F:Dy3+ phosphor

A trivalent Dy³⁺ -activated K₃ Ca₂ (SO₄ )₃ F fluoride-based phosphor was synthesized using a solid-state reaction method and characterized for its thermoluminescence (TL) application. The crystal structure and surface morphology of the as-synthesized material was analyzed using X-ray diffraction and scanning electron microscopy. A series of the K₃ Ca₂ (SO₄ )₃ F:Dy³⁺ phosphor was irradiated using γ-rays from a ⁶⁰ Co source and TL glow curves were recorded using a Nucleonix 1009I TL reader. The glow curve of the prepared phosphor showed a prominent single peak at 278°C. TL characteristics were maximum intensity at 1 mol% of Dy³⁺ ion with a single TL glow peak. The TL glow curve revealed linearity with increase in exposure dose range from 0.1 kGy to 3.0 kGy. Theoretical analysis of the TL glow curve of the γ-ray-irradiated sample was carried out using a computerized glow curve deconvolution method and trapping parameters such as activation energy and frequency factor were calculated using the initial rise method and Ilich's method. The synthesized Dy³⁺ -doped K₃ Ca₂ (SO₄ )₃ phosphor revealed excellent TL properties and was found to be a potential candidate for dosimetric applications.

Luminescence study of LiMgBO3 :Dy for γ-ray and carbon ion beam exposure

LiMgBO₃ :Dy³⁺ , a low Z_eff material was prepared using the solution combustion method and its luminescence properties were studied using X-ray diffraction (XRD), scanning electron microscopy (SEM), thermoluminescence (TL), photoluminescence (PL), Fourier transform infrared spectroscopy, and electron paramagnetic resonance (EPR) techniques. Reitvield refinement was also performed for the structural studies. The PL emission spectra for LiMgBO₃ :Dy³⁺ consisted of two peaks at 478 due to the ⁴ F_9/2 →⁶ H_15/2 magnetic dipole transition and at 572 nm due to the hypersensitive ⁴ F_9/2 →⁶ H_13/2 electric dipole transition of Dy³⁺ , respectively. A TL study was carried out for both the γ-ray-irradiated sample and the C⁵⁺ irradiated samples and was found to show high sensitivity for both. Moreover the γ-ray-irradiated LiMgBO₃ :Dy³⁺ sample showed linearity in the dose range 10 Gy to 1 kGy and C⁵⁺ -irradiated samples show linearity in the fluence range 2 × 10¹⁰ to 1 × 10¹¹ ions/cm² . In the present study, the initial rise method, various heating rate method, the whole glow curve method, glow curve convolution deconvolution function, and Chen's peak shape method were used to calculate kinetic parameters to understand the TL glow curve mechanism in detail. Finally, an EPR study was performed to examine the radicals responsible for the TL process.

Versatility of thermoluminescence materials and radiation dosimetry - A review

Thermoluminescence (TL) materials exhibit a wide range of applications in different areas such as personal dosimetry, environmental dosimetry, medical research etc. Doping of different rare earth impurities in different hosts is responsible for changing the properties of materials useful for various applications in different fields. These materials can be irradiated by different types of beams such as γ-rays, X-rays, electrons, neutrons etc. Various radiation regimes, as well as their dose-response range, play an important role in thermoluminescence dosimetry. Several TL materials, such as glass, microcrystalline, nanostructured inorganic materials and recently developed materials, are reviewed and described in this article.

Dy3+ -, Sm3+ -, Ce3+ - and Tb3+ -activated optical properties of microcrystalline BaMgP2 O7 phosphors

Photoluminescence (PL) and thermoluminescence (TL) properties of rare earth (RE) ion (RE = Dy³⁺ , Sm³⁺ , Ce³⁺ , Tb³⁺ ) activated microcrystalline BaMgP₂ O₇ phosphors are presented in this work. Non-doped and doped samples of BaMgP₂ O₇ were prepared using a solid state diffusion method and characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), PL and TL. The XRD measurement confirmed the phase purity of the BaMgP₂ O₇ host matrix. The average particle size was found through SEM measurement to be around 2 μm. All activators using the PL technique displayed characteristic excitation and emission spectra that corresponded to their typical f → f and f → d transitions respectively. Thermoluminescence measurements showed that BaMgP₂ O₇ :RE (RE = Dy³⁺ , Sm³⁺ , Tb³⁺ , Ce³⁺ ) and co-doped BaMgP₂ O₇ :Ce³⁺ ,Tb³⁺ phosphors have also TL behaviour.

Photoluminescence and thermoluminescence of K2 Mg(SO4 )2 :Eu and evaluation of its kinetic parameters

The K₂ Mg(SO₄ )₂ :Eu phosphor, synthesized by a solid-state diffusion method, was studied for its photoluminescence (PL) and thermoluminescence (TL) characteristics. The X-ray diffraction (XRD) pattern of the material was matched with the standard JCPDF No. 36-1499. For PL characteristics, K₂ Mg(SO₄ )₂ :Eu²⁺ showed an emission peak at 474 nm when excited at 340 nm, while it showed Eu³⁺ emission at 580 nm, and 594 nm splitting at 613 nm and 618 nm for an excitation of 396 nm wavelength due to radiative transitions from ⁵ D₀ to ⁷ F_j (j = 0, 1, 2, 3). The Commission International de I' Eclairage (CIE) chromaticity coordinates were also calculated for the K₂ Mg(SO₄ )₂ :Eu phosphor, and were close to the NTSC standard values. For the TL study, the prepared sample was irradiated using a ⁶⁰ Co source of γ-irradiation at the dose rate of 0.322 kGy/h for 2 min. The formation of traps in K₂ Mg (SO₄ )₂ :Eu and the effects of γ-radiation dose on the glow curve are discussed. Well defined broad glow peaks were obtained at 186°C. With increasing γ-ray dose, the sample showed linearity in intensity. The presence of a single glow peak indicated that there was only one set of traps being activated within the particular temperature range. The presented phosphors were also studied for their fading, reusability and trapping parameters. There was just 2% fading during a period of 30 days, indicating no serious fading problem. Kinetic parameters were calculated using the initial rise method and Chen's half-width method. Activation energy and frequency factor were found to be 0.77 eV and 1.41 × 10⁶  sec^-1 .

Luminescence characterization of Dy and Eu doped Na6 Mg(SO4 )4 phosphors

A series of single-phase phosphors based on Na₆ Mg(SO₄ )₄ (Z_eff  = 11.70) doped with Dy and Eu was prepared by the wet chemical method. The photoluminescence (PL) and thermoluminescence (TL) properties of Dy³⁺ - and Eu³⁺ -activated Na₆ Mg(SO₄ )₄ phosphors were investigated. The characteristic emissions of Dy³⁺ and Eu³⁺ were observed in the Na₆ Mg(SO₄ )₄ host. The TL glow curve of the Na₆ Mg(SO₄ )₄ :Dy phosphor consisted of a prominent peak at 234°C and a very small hump at 158°C. The TL sensitivity of the Na₆ Mg(SO₄ )₄ :Dy phosphor was found to be four times less than the commercialized CaSO₄ :Dy phosphor. The TL dose-response of the Na₆ Mg(SO₄ )₄ :Dy phosphor was studied from a dose range of 5-10 kGy and the linear dose-response was observed up to 1 kGy which is good for a microcrystalline phosphor. Trapping parameters for both the samples were calculated using the Initial Rise and Chen's peak shape methods.

Photoluminescence enhancement in Na3SO4Cl:X (X = Ce3+, Eu3+ or Dy3+) material

The compound Na3SO4Cl X (X = Ce(3+), Eu(3+) or Dy(3+)) prepared by the wet chemical method was studied for its photoluminescence (PL) and energy transfer characteristics. The PL from Na3 SO4 Cl:Ce(3+) shows strong emission at 322 nm at an excitation of 272 nm. Therefore, an efficient Ce(3+) → Dy(3+), Eu(2+) → Dy(3+) and Eu(2+) → Eu(3+) energy transfer had taken place in this host. The Dy(3+) emission caused by Ce(3+) → Dy(3+) energy transfer under ultraviolet (UV) wavelengths peaked at around 477 nm and 572 nm due to (4) F9/2 → (6) H15/2 and (6) H13/2 transitions with yellow-orange emission in the Na3 SO4 Cl lattice. An intense Dy(3+) emission was observed at 482 and 576 nm caused by the Eu(2+) → Dy(3+) energy transfer process and due to (4) F9/2 → (6) H15/2 and (4) F9/2 → (6) H13/2 transitions respectively. The Eu(3+) blue to red light emission caused by the Eu(2+) → Eu(3+) energy transfer peaked at 593 nm and 617 nm due to (5) D0 → (5) D3 transitions. The presence of trivalent Eu in Na3 SO4 Cl suggested the presence of Eu(3+) in the host compound that occupied two different lattice sites and that peaked at 593 and 617 nm due to (5) D0 → (7) F1 and (5) D0 → (7) F2 transitions respectively. The trivalent europium ion is very useful for studying the nature of metal coordination in various systems due to its non-degenerate emitting (5) D0 state. The present paper discusses the photoluminescence characteristics of Eu(2+) → Dy(3+) and Eu(2+) → Eu(3+) energy transfer. This compound may be useful as a lamp phosphor.

Synthesis and thermoluminescence characterizations of Sr2B5O9Cl:Dy3+ phosphor for TL dosimetry

The photoluminescence (PL) and thermoluminescence (TL) displayed by Dy-activated strontium haloborate (Sr2 B5 O9 Cl) were studied. A modified solid-state reaction was employed for the preparation of the phosphor. Photoluminescence spectra showed blue (484 nm) and yellow (575 nm) emissions due to incorporation of Dy(3+) into host matrix. The Dy-doped (0.5 mol%) Sr2 B5 O9 Cl was studied after exposure to γ-irradiation and revealed a prominent glow curve at 261°C with a small hump around 143°C indicating that two types of traps were generated. The glow peak at the higher temperature side (261°C) was more stable than the lower temperature glow peak. The TL intensity was 1.17 times less than that of the standard CaSO4 :Dy thermoluminescence dosimetry (TLD) phosphor, the phosphor showed a linear dose-response curve for different γ-ray irradiation doses (0.002-1.25 Gy) and fading of 5-7% was observed for higher temperature peaks upon storage. Trapping parameters and their estimated error values have been calculated by Chen's peak shape method and by the initial rise method. Values of activation energies estimated by both these techniques were comparable. The slight difference in activation energy values calculated by Chen's peak shape method indicated the formation of two kinds of traps Furthermore, slight differences in frequency values are due to various escaping and retrapping probabilities.

Enhanced luminescence and white light emission from Eu(3+) -co-doped K3 Ca2 (SO4 )3 Cl:Dy(3+) phosphor with near visible ultraviolet excitation for white LEDs

The luminescent properties of europium (Eu)- and dysprosium (Dy)-co-doped K3 Ca2 (SO4 )3 Cl halosulfate phosphors were analyzed. This paper reports the photoluminescence (PL) properties of K3 Ca2 (SO4 )3 Cl microphosphor doped with Eu and Dy and synthesized using a cost-effective wet chemical method. The phosphors were characterized by X-ray diffraction and scanning electron microscopy. The CIE coordinates were calculated to display the color of the phosphor. PL emission of the prepared samples show peaks at 484 nm (blue), 575 nm (yellow), 594 nm (orange) and 617 nm (red). The emission color of the Eu,Dy-co-doped K3 Ca2 (SO4 )3 Cl halophosphor depends on the doping concentration and excitation wavelength. The addition of Eu in K3 Ca2 (SO4 )3 Cl:Dy greatly enhances the intensity of the blue and yellow peaks, which corresponds to the (4)  F9/2  → (6) H15/2 and (4)  F9/2  → (6) H13/2 transitions of Dy(3+) ions (under 351 nm excitation). The Eu(3+) /Dy(3+) co-doping also produces white light emission for 1 mol% of Eu(3+) , 1 mol% of Dy(3+) in the K3 Ca2 (SO4 )3 Cl lattice under 396 nm excitation, for which the calculated chromaticity coordinates are (0.35, 0.31). Thus, K3 Ca2 (SO4 )3 Cl co-doped with Eu/Dy is a suitable candidate for NUV based white light-emitting phosphors technology.

Solution combustion synthesis of Dy(3+) and Ce(3+) activated Na2ZnSi2O6 phosphors

Here we first time reported Dy(3+) and Ce(3+) luminescence in novel Na2ZnSi2O6 phosphors by solution combustion synthesis prepared at 550 °C. Emission spectra of Na2ZnSi2O6:Dy(3+) phosphor was observed at 470 nm and 576 nm keeping excitation wavelength at 350 nm, where as Na2ZnSi2O6:Ce(3+) shows emission band at 452 nm monitoring excitation at 354 nm. XRD analysis was carried out to observe crystalline nature of the prepared phosphor.

Luminescent properties of MAl(SO4)2 Br:Eu(3+) (M = Sr or Mg) red phosphors for near-UV light-emitting diodes

Eu(3+) -activated MAl(SO4 )2 Br phosphors (where M = Mg or Sr) are successfully prepared using a wet chemical reaction technique. The samples are characterized by X-ray diffraction (XRD) and photoluminescence (PL) spectroscopies. The XRD pattern revealed that both the samples are microcrystalline in nature. PL of Eu(3+) -doped SrAl(SO4 )2 Br and MgAl(SO4 )2 Br phosphors exhibited characteristic red emission coming from the (5) D0  → (7) F2 (616 nm) electron transition, when excited by 396 nm wavelength of light. The maximum intensity of luminescence was observed at a concentration of 1 mol% Eu(3+) . The intensity of the electric dipole transition at 616 nm is greater than that of the magnetic dipole transition at 594 nm. The results showed that MAl(SO4 )2 Br:Eu(3+) , (M = Mg, Sr) phosphors have potential application in near-UV light-emitting diodes as efficient red-emitting phosphor.

Photoluminescence in K3 Ca2 (SO4 )3 Cl-doped Eu(3+) phosphor

In this article we report Eu(3+) luminescence in novel K3 Ca2 (SO4 )3 Cl phosphors prepared by wet chemical methods. The Eu(3+) emission was observed at 594 nm and 615 nm, keeping the excitation wavelength constant at 396 nm nearer to light-emitting diode excitation, Furthermore, phosphors were characterized by X-ray diffraction for the confirmation of crystallinity. The variation of the photoluminescence intensity with impurity concentration has also been discussed. Thus, prominent emission in the red region makes prepared phosphors more applicable for white light-emitting diodes.

Thermoluminescence characterization of Dy(3+) -activated Mg₅ (BO₃ )₃ F low Z(eff) phosphor

Thermoluminescence characteristics of Dy(3+) -activated Mg₅ (BO₃ )₃ F low Z(eff) phosphor are described. The Mg₅ (BO₃ )₃ F phosphor doped with Dy(3+) as activator was prepared by the modified solid-state reaction. Formation of the compound was confirmed by use of X-ray powder diffraction. The X-ray powder diffraction pattern of the as-prepared compound shows a good match with the available JCPDS data. The γ-irradiated Mg₅ (BO₃ )₃ F:Dy(3+) phosphor shows a simple glow curve peaking at about 148°C indicating that only one type of trap is being activated within a particular temperature range. The kinetic parameters, including activation energy and frequency factor were determined using Chen's method. The activation energy and frequency factors were 0.75 eV and 4.508 × 10(9) /s respectively. The Z(eff) ofMg₅ (BO₃ )₃ F:Dy(3+) phosphor was 9.84.