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Objective To explore the feasibility of quartz glass for radiotherapy dosimetry through the experimental study of the thermoluminescence characteristics of synthetic quartz glass. Methods The thermoluminescence glow curves of quartz glass under different annealing conditions were analyzed, the thermoluminescence characteristics of quartz glass were studied, and the measurement parameters were optimized. Using the Co-60 reference radiation field in the National Secondary Standard Dosimetry Laboratory, the quartz glass samples under different annealing conditions were irradiated following the dose levels of radiotherapy, i.e., 0.5, 1.0, 2.0, 4.0, 6.0, 8.0, and 10.0 Gy, respectively. According to the relationship between the absorbed dose of quartz glass and the relative thermoluminescence signal intensity, the linearity and dispersion of the dose response of quartz glass were obtained, and the feasibility of quartz glass for radiotherapy dosimetry was analyzed. Results The linear correlation coefficient of dose response of quartz glass under annealing condition of 430℃ for 10 min was 0.9984, and the dose response dispersion was 0.97% at the absorbed dose of 2 Gy. The linear correlation coefficient of dose response of quartz glass under annealing condition of 600℃ for 1 h was 0.9911, and the dose response dispersion was 1.4% at the absorbed dose of 2 Gy. Conclusion Preliminary results suggest that quartz glass with annealing condition of 430℃ for 10 min has the potential to be used for radiotherapy dosimetry.
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Objective To calculate the doses and their dose conversion coefficients for the personnel whose organs were under accidental exposure to three types of X-ray machines and two γ radiation sources, and to provide a simple method for rapid estimation of accidental doses. Methods The radiation source models of X-ray machines and two γ sources were established with the FLUKA simulation software and a Chinese reference voxel phantom was imported. The organ absorbed dose, dose conversion coefficient between organ absorbed dose and air Kerma, and conversion coefficient between organ absorbed dose and radiation source were calculated for a simulated scenario where the personnel were under antero-posterior exposure to radiation sources 1 meter away. Results For the lungs, heart, muscles, soft tissue, liver, skin, and brain, the conversion coefficient between organ absorbed dose and air Kerma was 0.30-1.19 (Gy/Gy). For X-ray machines, the conversion coefficient between organ absorbed dose and output for the six organs ranged from 6.12 × 10−3 to 2.90 × 10−2 Gy·m2/(mA·min). For γ radiation sources, the conversion coefficient between organ absorbed dose and activity for the six organs ranged from 1.12 × 10−8 to 7.01 × 10−8 Gy·m2/(GBq·s). Conclusion The conversion coefficient between organ absorbed dose and air Kerma and the conversion coefficient between organ absorbed dose and output or activity of a flaw detector can provide important dosimetric parameters for rapid assessment of similar radiation accidents.
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@#<b>Objective</b> To calculate the energy dependence of absorbed dose in EBT3 film, and to reveal the error in the measurement of proton absorbed dose by EBT3 film. <b>Methods</b> Beam energy was gradually increased in the clinical photon and proton energy ranges. Geant4 was used to calculate the difference in absorbed dose between EBT3 film and the same volume of water. The results were compared with the theoretical values. <b>Results</b> For photons and protons, the thresholds for absorbed dose with energy dependence were 100 keV and 11 MeV, respectively. The energy dependence was consistent with the theoretical values when the photon and proton energies were higher than the corresponding thresholds, and irrelevant to the theoretical values when energies were lower than the thresholds. The differences between the proton Bragg peak and 50% dose point and the actual positions were less than 1%. <b>Conclusions</b> For protons and photons with high energy, the energy dependence of absorbed dose in EBT3 film is negligible. For protons and photons with low energy, EBT3 film shows very different energy dependence of absorbed dose, which should be taken into consideration. The proton Bragg peak and 50% dose point measured by EBT3 film are basically the same as the actual positions.
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@#Introduction: A custom-made Perspex male pelvic phantom was developed to measure and to compare absorbed, surface and effective doses obtained from Single-Energy and Dual-Energy Computed Tomography (SECT & DECT). Methods: A customised Perspex pelvic phantom that mimicked male Asian reference size was scanned with SECT mode at 80 kV, 100 kV, 120 kV and 140 kV. In addition, the fabricated phantom was also scanned with DECT mode at 80/140 kV. Thermoluminescence dosimeters (TLD) were used to measure the charges and doses obtained from the TLD calibration curve. The absorbed dose, surface dose and effective dose obtained from SECT and DECT were measured and compared between these two modes. Results: The DECT showed 55.9 % dose reduction compared to SECT at 140 kV tube voltage. It shows that DECT can be used with radiation dose sparing, and it is in good agreement with routine CTDI phantom study. The effective dose of DECT of the abdominal imaging was within the acceptable effective dose limit of AAPM Report No. 96. This study also found that the surface dose was lower than values reported in previous studies for both modes. Conclusion: The fabricated Perspex phantom shows a great potential to be considered as an alternative phantom for the commercially existing phantom in CT dosimetry application.
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Objective In order to test and improve the monitoring technical level and ability of radiation environmental monitoring network in Zhejiang Province, ensure the accuracy and reliability of monitoring data and information, and obtain the cosmic ray response values of instruments and equipment in this year. Methods In September 2018，an intercomparison meeting of environmental gamma radiation air absorbed dose rate within the radiation environmental monitoring network of Zhejiang province was held in Ningbo，which was organized by Zhejiang Province Radiation Environmental Monitoring Center.A total of 33 sets of instruments from 15 member units participated in the intercomparison measurements at 5 environmental measuring points, and the comparison results were evaluated by the Z score values. Results It was found that the |Z| of all measurement results were less than or equal to 2, and the evaluation results were satisfactory and acceptable. Conclusion The measured data of scintillation counters have relatively wider dispersion，and the high pressure ionization chambers have bigger response valuetocosmic ray. The measurement results of the two kinds of instruments keep a good linearity except for the measurement points of cosmic ray response.
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Objective:To estimate the renal absorbed dose in the treatment of neuroendocrine tumors using 177Lu-DOTA-TATE and to assess the radiation safety and guide the treatment. Methods:The dosimetric calculations of patients treated with 177Lu-DOTA-TATE were carried out based on planar images of single photon emission computed tomography (SPECT). The regions of interest (ROIs) of the whole body and kidneys were delineated and converted into activity. Accordingly, the time-activity curves of the ROIs were obtained. The effective half-lives and cumulative activity of ROIs were calculated through the fitting of a single exponential equation of the ROIs. Then the absorbed doses were calculated based on the medical internal radiation dosimetry (MIRD) formalism. Results:A total of 11 patients with neuroendocrine tumors received 18 cycles of treatments with 177Lu-DOTA-TATE. The effective half-lives of 177Lu-DOTA-TATE in the whole body and kidneys were 20.0-99.8 h and 38.2-75.2 h, respectively, with an average of (57.3 ± 21.4) h and (53.1 ± 12.5) h, respectively. The renal absorbed doses of 177Lu-DTA-TATE were 0.25-1.48 mGy/MBq, with an average of (0.90 ± 0.31) mGy/MBq. The minimum and maximum renal absorbed doses in a single treatment cycle were 1.8 Gy and 9.6 Gy, respectively, while the maximum renal absorbed dose in multiple treatment cycles was 21.7 Gy. Conclusions:The renal absorbed doses in the treatment of neuroendocrine tumors using 177Lu-DOTA-TATE were estimated. The result indicate that the renal absorbed doses were lower than the tolerable dose limits. This study is expected to guide the precise treatment of neuroendocrine tumors.
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En esta investigación se planteó como objetivo la verificación del comportamiento dosimétrico del Sistema de Planificación de Tratamiento (TPS) de Radioterapia mediante las curvas de calibración de Densidades Electrónicas Relativas (DER). Este estudio se realizó en el Hospital de la Sociedad de Lucha Contra el Cáncer (SOLCA) Núcleo Loja, usando un fantoma antropomorfo CIRS 062M y un tomógrafo Toshiba Activion 16. Para determinar la nueva curva de calibración DER se tomaron los valores de densidades electrónicas especificadas en el manual del fantoma y las Unidades Hounsfield de la imagen tomográfica. Se realizó controles de calidad dosimétricos y verificación dosimétrica en tres casos clínicos: tórax, pelvis y cráneo; para realizar las pruebas dosimétricas se utilizó un acelerador CLINAC CX, cámara de ionización PTW tipo Farmer con volumen sensible de 0,6 cm3 y un electrómetro PTW UNIDOS E. Los resultados mostraron que las medidas para cada inserto del fantoma en ningún caso excedieron los límites establecidos de ± 20 UH, para el tomógrafo y el TPS; las pruebas de control de calidad no superaron el límite máximo de desviaciones en el cálculo de dosis absorbida por el TPS y la obtenida por medición de ± 4 % establecida por la IAEA y las verificaciones dosimétricas en tórax, pelvis y cráneo, determinaron que las desviaciones en el cálculo de la dosis absorbida por el TPS y la obtenida por medición no superaban la tolerancia del ± 5 % establecida por la ICRU.
In this research, the aim was to verify the dosimetric behavior of the Radiotherapy Treatment Planning System (TPS) using the Relative Electron Density (DER) calibration curves. This study was carried out at the SOLCA (Society of Fight Against Cancer) hospital in Loja, using an CIRS model 062M anthropomorphic phantom and a Toshiba Activion 16 tomograph. To determine the new DER calibration curve, the values of the electron densities specified in the manual of the phantom and the Hounsfield Units of the tomographic image were taken. Dosimetric quality controls were made in the location of three clinical cases: thorax pelvis and skull; used a CLINAC CX accelerator was used to perform the dosimetric tests, PTW ionization chamber type Farmer with sensitive volume of 0.6 cm3 and a PTW UNIDOS E electrometer. The results showed that the measurements for each insert of the phantom in no case exceeded the established limits of ± 20 UH, for the tomograph and the TPS; the quality control tests did not exceed the maximum limit of deviations in the calculation of dose absorbed by the TPS and the one obtained by measurement of ± 4% established by the IAEA and the clinical planning in the thorax, pelvis and skull, determine that the deviations in the calculation of the dose absorbed by the TPS and that obtained by measurement, they do not exceed the tolerance of ± 5% established by the ICR.
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Radiotherapy, Computer-Assisted/instrumentation , Radiotherapy Planning, Computer-Assisted/methods , Electrons , Radiation Dosage , Radiometry , Radiotherapy Dosage , Bone Density/physiology , Phantoms, Imaging , Ecuador , Cone-Beam Computed Tomography/methodsABSTRACT
Objective To study the methods to estimate absorbed dose to eye lens of infants from CT scanning using different protocols and try to find a practical quick way for estimating absorbed dose to eye lens.Methods By scanning one-year old anthropomorphic phantom using 7 kinds of different protocols,all TLDs were measured for final estimation of absorbed dose to eye lens using two different dose conversion methods.Meanwhile,linear regression equation was established between absorbed dose to eye lens and CTDI.Results Absorbed doses to eye lens of infants from children CT scanning using 7 kinds of different protocols were (9.96±0.69) mGy in head axis,(7.01±0.42) mGy in head helical,(12.60± 0.97) mGy in sinus,(12.97±0.42) mGy in inner ear,(0.63±0.03) mGy in neck soft tissue,(8.89± 0.44) mGy in cervical vertebra,and (0.34± 0.01) mGy in chest,respectively.There were statistically significant difference in doses among different groups (F =846.826,P ＜ 0.05).For different scanning locations,there was linear relation between absorbed dose to eye lens and CTDI(r=0.986-0.999,P＜ 0.05).Conclusions Absorbed dose to eye lens of infants from children CT scaning with single dose may not be above threshold dose.In addition,absorbed dose to eye lens can be estimated quickly by linear regression equation between absorbed dose to eye lens and CTDI.
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Objective To measure absorbed dose and verify two-dimensional dose distribution from IMRT MLC using thermoluminescence dosimeters (TLDs) and films.Methods The teflon phantom was scanned by CT and its images were transmitted to TPS for planning.The 6 Gy-corresponding MUs were calculated at 90 cm SSD and 10 cm depth and on 5 cm × 5 cm radiation field.All the plans were implemented at 7 medical linear accelerators,which were produced by Varian,Elekta and Siemens and selected from 7 third-grade first-class hospitals according to the technical conditions of various regions in Sichuan province.The homogeneous solid phantoms used in hospitals were covered by 30 cm × 30 cm and 25 cm × 25 cm films.Then,the films were covered by thicker-than-20 cm phantoms.Finally,the plans were implemented by aligning the center of beams to the films center.Results The relative deviations of the measured absorbed dose to TPS-planned dose were 1.4％,3.7％,-2.5％,-0.3％,4.9％,4.9％,5.0％ for TLDs and 4.7％,4.3％,1.5％,3.9％,-1.6％,3.3％,-1.3％ for films,respectively,all consistent with the limit of less than 5％.The passing rates of 2D dose distribution (3 mm/3％) were 99.9％,98.5％,98.5％,97.9％ and 70.0％ for 5 accelerators,with only one not consistent with the requirements.Conclusions It is convenient to measure the absorbed dose to photon beam field and verify two-dimensional dose distribution using TLDs and films,which can provide quality assurance for radiation treatment plans.
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Objective To verify the absorbed dose and two-dimensional dosimetry delivered by MLC-shaped IMRT photon beams using thermoluminescent dosimeters (TLDs) and radiochromic films.Methods Different types of medical linear accelerators at 7 third-grade first-class hospitals in Hubei were selected for this audit study.Besides TLDs and films,a small polystyrene phantom measuring 15 cm × 15 cm × 15 cm,supplied by the International Atomic Energy Agency (IAEA),was also used.The TPS dose calculation were performed with 6 MV X-ray beam and by delivering 6 Gy dose to the TLDs or films at 10 cm depth for 5 cm × 5 cm field size at 90 cm SSD.After irradiation,comparations were conducted of dose derivations between TPS-calculated values and TLD-or film-measured values.The two-dimensional dosimetry audit was carried out by using 30 cm × 30 cm homogeneous solid phantoms in which a 25 cm × 25 cm film was located at 5 cm depth.A single-filed profile generated by TPS was delivered to the film,and the film was measured.And then,two-dimensional dose distribution was analyzed using the film analysis system.Results The results suggested that the relative deviations of TLD and film to TPS dose was-8.5％ and-1.9％ for accelerator 1,5.4％ and 0.5％ for accelerator 7,respectively,whereas those for other accelerators were within ± 5％.The passing rates for two-dimensional dose distribution at all accelerators were all higher than 90％.Conclusions TLD and film quality audit for IMRT can be applied for a wide range of application in view of its simplicity,reliability and postal convenience.
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Objective To validate the absorbed dose and two-dimensional dose distribution from photon beam by using Thermoluminescent dosimeter (TLD) and film for intensity modulated radiation therapy (IMRT).Methods A total of 8 medical accelerators were selected among 5 third-grade first-class hospitals using non-probabilistic sampling method in Henan province.TLDs were put into polytetrafluoroethylene solid phantom with size of 5 cm × 15 cm × 15 cm provided by IAEA.After CT scanning,the radiotherapeutic plans were formulated through image transmission to the treatment planning system (TPS).The IMRT plan was implemented for measurement of TLD-absorbed doses under the conditions of 5 cm × 5 cm field,90 cm SSD,10 cm depth,6 MV photon beam and 6 Gy absorbed dose and corresponding measurement unit (MU).The 25 cm × 25 cm film-absorbed dose measurement was made in the same manner as TLD under the conditions of 30 cm × 30 cm size,20 cm thickness,95 cm SSD and 5 cm depth.Results Of eight accelerators,the requirements can be met for 7 accelerators with respect to the relative deviation of TLD absorbed dose except 1.For film,relative deviations were all consistent with the requirements.The passing rate of two-dimensional dose distribution was in line with the requirements for 7 accelerators except 1.Conclusions TLD and film can be used to check the MLC field absorbed dose and two-dimensional dose distribution.This methodis simple,easy to operate and suitable for the implementation of IMRT quality control in hospitals in Henan province.
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Objective To develop the methodology for using TLDs and films to measure absorbed dose and 2D dose distribution produced by the multi-leaf collimator (MLC) in intensity modulated radiotherapy (IMRT),in order to provide the guidance on dose quality audit in IMRT.Methods A total of 30 different-typed accelerators were selected from 27 hospitals in Jiangsu,Sichuan,Hubei and Henan provinces,including 17 Varian accelerators,10 Elektas and 3 Simens.The same batch of films and TLDs were put in a 2 cm-thick solid plate for fixation and then loaded in a 15 cm × 15 cm × 15 cm polysyrene solid phantom supplied by International Atomic Energy Agency(IAEA) in terms of 90 cm SSD,19 cm depth,10 cm × 10 cm field at different doses.The standard dose curves wcrc established for film and TLD,respectively.The irradiated film was measured and then sent to the External Audit Group (EAG) in China.The TLD-and film-absorbed doses were compared with TPS-calculated doses.The 2D dose distribution on the IRMT MLC field was measured using films.The homogeneous phanton of 30 cn × 30 cm was scanned by CT and the image was transferred to the TPS.The IMRT was implemented with 6 Gy fractionated irradiation by placing a 25 cm × 25 cm film on the phantom surface at 95 cm SSD and at 5 cm depth.The irradiated film was sent to the IAEA dosimetry laboratory for measurement and calculation.2D dose distribution verification was conducted in thc same way consistent with the procedure of international multi-radiotherapy center.The 3 mm/3％ passing rate was calculated for 2D dose distribution and compared with the film-measured and TPS calculated result.Results IAEA requires the relative deviation of TLD and film measured absorbed dose are with in ± 5％.The relative deviation of TLD-and filmmeasured to TPS-calculated absorbed dose was within the range of ±0.7％-± 8.5％ and within ±0.3％ ±7.8％ in Jiangsu,Sichuan,Hubei and Henan provinces,respectively.IAEA requires the 3 mm/3％ passing rate of film-measured 2D distribution to be 90％.The result of the present study were up to 94.0％.The verification result of 2D dose distribution were within 70.0％-99.9％ in Sichuan,Jiangsu,Hubei and Henan provinces.Conclusions The adsorbed dose and 2D distribution can be audited using TLDs and films for MLC in IRMT.The method is scientific and applicable,economical and convenient for development of dose quality audit for a wide range of IRMT.
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Objective To explore the effect of DAVID system on the beam dosimetry of ELEKTA Synergy accelerator. Methods Three-dimensional water phantom system was used to measure the values of percentage depth dose (PDD) in different fields,gun-trarget(G-T)in different fields and depths as well off-axis ratio(OAR)at left-right(L-R)direction when the accelerator was equipped with DAVID system or not. Results DAVID system had no effects on PDD and OAR, while influenced the absorbed dose so that the ray was attenuated by 7%.Conclusion The field parameters have not to be modified for the planning system when using DAVID system,but the dose correction has to be performed according to ray transmission factors.
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Se desarrolló una metodología para la validación y el control de rutina del proceso de irradiación que se realiza en un irradiador autoblindado con fuentes de 60Co. Esta metodología fue aplicada a un irradiador modelo ISOGAMMA LLCo con el objetivo de garantizar la correcta explotación del equipo, la eficiencia de los servicios brindados y la obtención, en forma consistente, de un producto que cumpla con los atributos de calidad y las especificaciones predeterminadas
A methodology was developed for the validation and routine control of the irradiation process performed in a self-shielding gamma irradiator with 60Co sources. This methodology was applied to an irradiator model ISOGAMMA LLCo in order to ensure the proper operation of the equipment, efficiency of services provided and to consistently obtain, , a product that meets the quality attributes and default specifications
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Objective To evaluate the effect of ion chamber sensitive volume on absolute dose verification in CyberKnife plan.Methods Solid water phantoms were scanned by a CT scanner, single-field plan, multi-field isocentric plan and sequential optimized plan were designed by the treatment planning system.Absolute doses were measured at the specified point in each plan using the ion chambers with sensitive volumes of 0.007 cm3(A16), 0.24 cm3(A12 s), and 0.6 cm3(PTW30013) and compared with calculated values.Results For the single-field plan, the relative error increased as the aperture size of collimator decreased;with relative errors within ±2%, the smallest aperture sizes of collimator were 12.5 mm (A16), 25 mm (A12 s), and 30 mm (PTW30013).For the multi-filed isocentric plan, the relative errors were 0.26%±3.90%(A16),-6.28%±14.33%(A12 s), and-9.41%±14.10%(PTW30013).For the sequential plan optimized with 15 mm cone, the relative error was 0.79%±1.43%;for the sequential plan optimized with 7.5 mm cone, the relative error was 2.01%±8.39%.In absolute dose verification for clinical plans, there was no significant difference between the results measured by these ion chambers (P=0.985).Conclusions There is no significant effect of ion chamber sensitive volume on absolute dose verification in CyberKnife plan under the following two situations:(1) the collimator with a relatively large aperture is used;(2) the sensitive volume of ion chamber is totally covered by the prescription isodose line.
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Objective To measure the actual absorbed dose of the target in the QUASAR Respiratory Motion Phantom using the CyberKnife Synchrony Respiratory Tracking System, and to evaluate the effect of density heterogeneity on the absorbed dose of tumor gross target volume ( GTV ) . Methods Nine groups were obtained by making different patterns of QUASAR phantom:rib thickness of 0, 20, and 50 mm, and motion amplitudes of 0, 10, and 15 mm. The nine groups were treated with static computed tomography (CT) in different time phases of four-dimensional CT (4DCT) plan, with the same beam and number of monitor units, and the 4D accumulated dose was calculated. The doses of static and 4D plans were calculated using Ray-tracing and Monte Carlo algorithms, and the absorbed doses of GTV in the nine groups were measured at the same time. Results There were a decrease in calculated absorbed dose of GTV and an increase in deviation between the planned and actual dose, with the increases in simulated rib thickness and motion amplitude. Conclusions The density heterogeneity has an impact on the absorbed dose of GTV. Both static CT and 4DCT plan can evaluate the absorbed dose of GTV in case of small rib thickness and motion amplitude, and 4DCT plan with Monte Carlo algorithm may be the optimal method for evaluation of the absorbed dose of GTV in case of large rib thickness and motion amplitude ( deviation<3%)
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Objective To measure the actual absorbed dose of the target in the QUASAR Respiratory Motion Phantom using the CyberKnife Synchrony Respiratory Tracking System, and to evaluate the effect of density heterogeneity on the absorbed dose of tumor gross target volume ( GTV ) . Methods Nine groups were obtained by making different patterns of QUASAR phantom:rib thickness of 0, 20, and 50 mm, and motion amplitudes of 0, 10, and 15 mm. The nine groups were treated with static computed tomography (CT) in different time phases of four-dimensional CT (4DCT) plan, with the same beam and number of monitor units, and the 4D accumulated dose was calculated. The doses of static and 4D plans were calculated using Ray-tracing and Monte Carlo algorithms, and the absorbed doses of GTV in the nine groups were measured at the same time. Results There were a decrease in calculated absorbed dose of GTV and an increase in deviation between the planned and actual dose, with the increases in simulated rib thickness and motion amplitude. Conclusions The density heterogeneity has an impact on the absorbed dose of GTV. Both static CT and 4DCT plan can evaluate the absorbed dose of GTV in case of small rib thickness and motion amplitude, and 4DCT plan with Monte Carlo algorithm may be the optimal method for evaluation of the absorbed dose of GTV in case of large rib thickness and motion amplitude ( deviation<3%)
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Objective To compare the iodine contrast agent dosage,radiation dose and image quality in CT pulmonary angiogra-phy (CTPA)with low tube voltage and high tube current in 64-slice spiral CT.Methods 60 patients with suspected pulmonary em-bolism in our hospital were randomly chosen and divided into three groups:Group Ⅰ:20 patients,using 120 kV,180 mA,contrast dose of 70 mL.Group Ⅱ:20 patients,using 100 kV,280 mA,contrast dose of 50 mL.Group Ⅲ:20 patients,using 80 kV,automat-ic tube current modulation techniques (300-500 mA),comparative dose of 30 mL.CT values and image noise of three pulmonary central areas and a segment branch were measured in each group.Objective indicators,subjective image quality assessment,CT dose index volume (CTDIvol),dose-length product (DLP)and effective absorbed dose (ED)were compared in three groups to evaluate the value of low kV,high mA with low-contrast dose in CTPA.Analysis of variance and t-test was used for data analysis.Results Compared with those of the standard method of CTPA,all pulmonary dry in two groups of low dose were well displayed.There was no statistical significance between each two groups in image quality score (P > 0.05),but was statistical significance in CT values, noise,SNR and CNR (P < 0.01).The CT radiation dose,CTDIvol and DLP of Group Ⅱ and Group Ⅲ were significantly lower than those of Group Ⅰ (P < 0.01).Conclusion Compared with traditional methods,low dose contrast agent injections under 80 kV could reduce the dose of contrast agent and the effect of hardening artifacts due to contrast agent in superior vena cava on right pul-monary artery.It is helpful to reduce the risk of contrast induced nephropathy and reduce patients’exposure to X-ray radiation.
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Aim: The purpose of this paper was to review various dosimeters used in dentistry and the cumulative results of various studies done with various dosimeters. Materials and Methods: Several relevant PubMed indexed articles from 1999 to 2013 were electronically searched by typing “dosimeters”, “dosimeters in dentistry”, “properties of dosimeters”, “thermoluminescent and optically stimulated dosimeters”, “recent advancements in dosimetry in dentistry.” The searches were limited to articles in English to prepare a concise review on dental dosimetry. Titles and abstracts were screened, and articles that fulfilled the criteria of use of dosimeters in dental applications were selected for a full‑text reading. Article was divided into four groups: (1) Biological effects of radiation, (2) properties of dosimeters, (3) types of dosimeters and (4) results of various studies using different dosimeters. Conclusion: The present review on dosimetry based on various studies done with dosimeters revealed that, with the advent of radiographic technique the effective dose delivered is low. Therefore, selection of radiological technique plays an important role in dental dose delivery.
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Dentistry/methods , Dentistry/diagnostic imaging , Radiometry/instrumentation , Radiometry/methods , Radiotherapy Dosage/methodsABSTRACT
Objective To measure and analyze the radiation dose for patients undergoing nuclear medicine examination,and to characterize radiation exposure of patients by using the estimated effective dose.Methods Patients undergoing nuclear medicine examinations were classified and the radiation doses from radiopharmaceuticals to patients were measured and calculated.Meanwhile,radiation exposure from computed tomography (CT) procedure was calculated on the basis of CT protocols and patients' information.The effective doses to patient from both the radiopharmaceutical and CT scan radiation were calculated and the factors influencing patient radiation doses were analyzed.Results For the patients undergoing positron emission tomography-computed tomography (PET-CT) examination,the average effective doses from positron radiopharmaceutical 18F-fluorodeoxyglucose (18F-FDG),18F-fluoro-l-thymidine (18 F-FLT),11C-choline,11 C-methylmethionine (11 C-MET) and 11 C-acetate (11 C-Ac) were (5.06 ± 0.73),(4.74±1.29),(1.71 ±0.05),(3.18±0.69) and (1.08±0.19) mSv,respectively.CTscan caused average effective dose was (8.80 ± 0.58) mSv.If a full diagnostic CT investigation was performed,the effective dose might be up to 27 mSv.Whereas for emission computed tomography (ECT) examinations,the average effective dose to the patients irradiated by single photon radiopharmaceutical 99Tcm-methylenediphosphonate (99Tcm-MDP),99Tcm-macroaggregated albumin (99Tcm-MAA),99Tcm-diethylentriaminpentaacetic acid (99 Tcm-DTPA),99Tcm-methoxyisobutyl isonitrile (99 Tcm-MIBI) and 99Tcm-pyrophosphate (99Tcm-PYP) were (4.63 ± 0.01),(1.71 ± 0.01),(1.18 ± 0.01),(7.19 ± 0.03) and (4.18 ± 0.01) mSv,respectively.Conclusions Radiopharmaceutical irradiation caused effective dose to the patients undergoing nuclear medicine examinations is from 1.08 to 7.19 mSv,while CT scan cause average effective dose is 8.80 mSv in PET-CT examination.