Research of TLD calibrated in different standard X-ray RQR radiation field in terms of eye lens dose Hp(3) / 中华放射医学与防护杂志

Objective@#To compare the calibration result of standard X-ray RQR radiation field between SSDL (NIRP) and CEA LIST LNHB(France), and to explore the feasibility of calibrating Hp(3) in standard X-ray RQR radiation field of SSDL(NIRP).@*Methods@#Using a column model with a diameter and high of 20 cm, TLD was calibrated in SSDL (NIRP) and CEA LIST LNHB (France) to measure the personal dose equivalent eye lens dose Hp(3), X-ray RQR radiation field included RQR4(60 kV), RQR7(90 kV), RQR9(120 kV), with energy response, angle response and linear response.@*Results@#In terms of energy response, the calibration results of TLD in both SSDL (NIRP) and CEA LIST LNHB (France) were in good agreement. The difference between exposure value and response value was less than 10%. In terms of angle response, the calibration result of TLD in CEA LIST LNHB (France) was better in SSDL(NIRP). The difference between exposure value and response value in CEA LIST LNHB (France) was less than 6%, while the difference between exposure value and response value in SSDL(NIRP) was more than 10% at angle of 20°. In terms of linear response, both calibration result of SSDL (NIRP) and CEA LIST LNHB (France) were in good agreement.@*Conclusions@#The standard X-ray RQR field in SSDL (NIRP) can be used for the calibration of Hp(3).

Research of TLD calibrated in different standard X-ray RQR radiation field in terms of eye lens dose Hp (3) / 中华放射医学与防护杂志

Objective To compare the calibration result of standard X-ray RQR radiation field between SSDL (NIRP) and CEA LIST LNHB (France),and to explore the feasibility of calibrating Hp (3) in standard X-ray RQR radiation field of SSDL (NIRP).Methods Using a column model with a diameter and high of 20 cm,TLD was calibrated in SSDL (NIRP) and CEA LIST LNHB (France) to measure the personal dose equivalent eye lens dose Hp (3),X-ray RQR radiation field included RQR4 (60 kV),RQR7 (90 kV),RQR9 (120 kV),with energy response,angle response and linear response.Results In terms of energy response,the calibration results of TLD in both SSDL (NIRP) and CEA LIST LNHB (France) were in good agreement.The difference between exposure value and response value was less than 10％.In terms of angle response,the calibration result of TLD in CEA LIST LNHB (France) was better in SSDL (NIRP).The difference between exposure value and response value in CEA LIST LNHB (France) was less than 6％,while the difference between exposure value and response value in SSDI (NIRP) was more than 10％ at angle of 20°.In terms of linear response,both calibration result of SSDL (NIRP) and CEA LIST LNHB (France) were in good agreement.Conclusions The standard X-ray RQR field in SSDL (NIRP) can be used for the calibration of Hp (3).

A comparative study for surface dose evaluation in conventional treatment of carcinoma breast patients irradiated with Co-60 and 6 MV radiation beam

Aim: In the present study, surface doses within the target area and contralateral breast (CLB) received during conventional treatment of carcinoma breast are evaluate and compared for treatment on two different beam energies, i.e., Co-60 γ-ray and 6 MV X-ray beams with thermoluminescent dosimeter, LiF:Mg, Ti (TLD-100). Materials and Methods: The study includes a group of 23 patients comprising 11 patients treated with Co-60 γ-ray beam and 12 patients by 6 MV X-ray beam. Results and Discussion: The treatment using Co-60 γ-ray and 6 MV X-ray beams contributes an average percentage dose of 8.15% ± 0.56% and 4.73% ± 0.94%, respectively, to CLB in mastectomy patients. The contribution of tangential fields (mastectomy) to the CLB doses ranges between 12.71 and 16.40 cGy (5.45%–7.03%) for treatment with Co-60 γ-ray beam and 6.33–10.95 cGy (1.86–4.69%) for treatment with 6 MV X-ray beam. The supraclavicular field (SCF) contributes 1.45%–1.93% and 1.02%–1.43% for treatment with Co-60 γ-ray and 6 MV X-ray beams, respectively. The average surface dose (normalized with breast dose) 89.1% ± 8.5% for Co-60 beam in the SCF region differs significantly from the 60.2% ± 13.0% value for 6 MV X-ray beam. Conclusion: The CLB doses for mastectomy patients are higher for Co-60 beam as compared to 6 MV X-ray beam, and better dose homogeneity is achieved within the irradiated breast from 6 MV X-ray beam. The CLB doses are slightly higher for patients treated with breast conservative radiotherapy or lumpectomy. The average surface dose to SCF decreases by ~30% of treated breast dose for treatment with 6 MV X-ray beam

Analysis on eye lens doses and hand doses of working operator in 125I seed source implantation / 中华放射医学与防护杂志

Objective To measure the doses to eye lens and hands of workers,using thermo luminescent dosimeter (TLD) and optically stimulated luminescence dosimeter (OSLD).Methods TLDs in the same batch were annealed,packed and stuck to the flat abdomen of Alderson-Phantom at a distance of about 15 cm from 125I seed source,while irradiated at different doses:1.0,1.5,3.0,5.0,10.0,12.0,20.0,25.0,30.0,50.0 and 60.0 μ Gy.And then TLDs were measured by dosimeters to establish a dose calibration curve.By implanting seed source into the selected lung for 14 cases,belly for 10 cases,pelvic for 5 case and neck for 6 cases while placing calibrated TLDs on the left,middle and right above eyes,left and right hands of the workers to obtain the location-specific kerma values.Finally,the conversion factors Hp (3) and Hp (0.07) were used to calculate the values of dose equivalent to eye lens and hands.Additionally,OSLDs were used to measure the doses to workers in the same way.Results The TLD-measured eye lens dses to the operator and his assistant were 0.8 and 1.6 mSv in lungs,1.3 and 1.2 mSv in bellies,0.9 and 0.6 mSv in pelves,0.3 mSv in necks,respectively.Meanwhile,hand doses to the operator and his assistant were 1.4 and 2.1 mSv in lungs,1.2 and 1.0 mSv in bellies,0.5 and 0.9 mSv in pelves,0.1 mSv in necks,respectively.The maximum doses to eye lens and hands were 1.2 and 1.0 mSv,respectively in a single treatment.OSLD-measured dose equivalents from lung therapy were 0.2 and 0.1 mSv for eye lens of the operator and his assistant and 0.4 and 0.6 mSv for hands.For belly therapy,the accumulated dose equivalent to hands of the operator was 0.1 mSv while those for other types of therapy were 0 mSv.Conclusions TLDs have the capability to measure not only accumulated dose but also dose equivalent from a single therapy According to ICRP 118 publication and as estimated in the present study,the number of therapy should be not more than 17 every year.OSLDs only give the accumulated dose,the accuracy of which needs to be studied in low-dose measurement.

Simulated measurement of doses from kilovoltage cone beam CT based on a 5 years old pediatric anthropomorphic phantom / 中华放射医学与防护杂志

Objective To use thermoluminescense dosimeters (TLDs) to evaluate the radiation doses to various critical organs in the computerized imaging reference systems (CIRS) 5 years old pediatric anthropomorphic phantom result ing from Varian kilovohage cone beam CT (kV-CBCT) system based on the standard scanning protocols.Effective dose were also calculated based on dose measurement.Methods A batch of TLDs with consistency no larger than 2％ were selected and annealed.First,the doses in an anthropomorphic pelvic phantom were measured using a CT chamber and TLDs,respectively,based on the standard pelvic protocols.The ratio of the both measurements is the TLD conversion coefficient.Other TLDs from the same batch were placed between two tissue-equivalent inserts and placed into the pre-drilled organ cavities of the pediatric phantom.By using standard protocols,the organs dose were measured,based on which the corresponding effective doses were calculated.Results The TLD conversion coefficient was 3.91 mGy/per reading.By using the standard head,low-dose thorax,pelvis protocol,the whole body effective dose was 0.63,6.85 and 19.3 mSv,respectively.Conclusions It is feasible for using the CT chamber-calibrated TLDs to measure the radiation doses from kV-CBCT to pediatric anthropomorphic phantom.The effective dose in pelvic protocol was higher than in thorax and head protocol,indicating that the pelvic protocol has a penitential to lead to larger radiation damage and higher risk of secondary cancer.

Verification of photon beam field absorbed dose and two-dimensional dose distribution in intensity modulated radiotherapy in Sichuan province / 中华放射医学与防护杂志

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.

Verification of absorbed dose and single-field dosimetry of MLC-shaped IMRT photon beams in Hubei province / 中华放射医学与防护杂志

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.

Validation study of photon beam absorbed dose and two-dimensional dose distribution in intensity modulated radiotherapy in Henan province / 中华放射医学与防护杂志

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.

Dosimetric verification on intensity modulated radiotherapy in Jiangsu province / 中华放射医学与防护杂志

Objective To explore the dosimetric verification method for absorbed dose and twodimensional dose distribution generated through multi-leaf collimator in radiotherapy.Methods A total of 8 medical accelerators were selected in Jiangsu province.Under 6 MV X-rays with a 5 cm × 5 cm field,the thermoluminescent dosimeter (TLD) and EBT3 radiochromic film (RCF) were used to audit the values calculated by treatment planning system (TPS).RCF was used to verify two-dimensional dose distribution under the 6 MV MLC beams for intensity modulated radiation therapy (IMRT).Results The relative dose deviation was from-1.4％ to 6.8％ for TLD and from-1.8％ to 7.8％ for RCF,with 7 accelerators meeting with the IAEA deviation requirement of ± 5％.The passing rates of two-dimensional dose distribution were between 73.7％ and 97.0％,with 7 accelerators greater than 90％.Conclusions TLD and RCF are feasible and suitable for large-scale verification of IMRT TPS absorbed dose and twodimensional dose distribution.

Development of methodology for dose quality audit of multi-leaf collimator in intensity modulated radiotherapy / 中华放射医学与防护杂志

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.

The measurements of eye lens dose for occupational staff in interventional procedures / 中华放射医学与防护杂志

Objective To establish methods of measuring the eye lens dose to interventional staff,to obtain relevant dose data and to provide a scientific basis for reducing eye lens dose.Methods Two kinds of dosimeters,thermoluminescent dosimeter (TLD) and optically stimulated luminescence dosimeter (OSLD),were selected to measure the personal dose equivalent HP (3) to eye lens of occupational staff in several kinds of interventional procedures,including cardiovascular interventional procedures,cerebrovascular interventional procedures etc.Five types of Digital Subtraction Angiography (DSA) equipment were chosen in the study,including single tube equipment and double tube equipment.Results The eye lens dose HP (3) to interventional staff varied significantly with different interventional procedures.The lowest dose is shown in the coronary angiography procedure,while the highest dose shown in the cerebral stenting procedure.For the same type of interventional procedure,the eye lens dose to the primary interventionist was the highest.For same interventionist,the dose to the left eye was obviously higher than that to the right eye.In addition,the measured results of OSLD were apparently higher than that of TLD.Conclusions Both TLD and OSLD could be used to measure eye lens dose,and the ways of calibrating TLD to evaluate personal dose equivalent HP (3) were feasible.The reason of significant difference between the measured results of TLD and OSLD needs further research.

The dosimetric characteristics of thermoluminescent dosimeter / 中华放射医学与防护杂志

Objective To study the dosimetric characteristics of thermoluminescent dosimeter (TLD).Methods A total of 350 pieces of TLD 2000 type TLDs having the same sensitivity within ± 3.0％ were selected.The TLDs were irradiated to study the repeatability and dosage effect of TLDs by using 6 MV X-rays and 125I seeds.In order to study the dose response,the TLDs were irradiated at different dosages by using 137Cs (662 keV γ-rays),125I seeds and 6 MV X-rays.In order to study the energy response,the TLDs were exposed to the same dose,from 125I seeds,137Cs and X-rays(48,65,83,118,250 keV and 6 MV).Results The maximum deviations of the repeatability were 2.7％ and 4.0％ for 6 MV X-rays and 125I seeds,respectively,and there was no effect of dose rate observed.The dose response of TLDs to 137Cs and 125I seeds were linear.For 6 MV X-rays,the linear response was within the range of 0.74-10 Gy and non-linear range was beyond 10 Gy.The energy response to 125I seeds,48,65,83,118,250 keV and6 MV X-rays,relative to the energy response of 137Cs,were 1.70,1.25,1.08,0.99,0.91,0.96 and 1.22,respectively.Conclusions TLD 2000 has a good repeatability and linear dose response for 137Cs,125I seeds and 6 MV X-rays with no dose rate effects,but the dose response is energy dependent.

Increasing Radiation Doses from Computed Tomography versus Diagnostic Reference Levels: How Compliance Are We.

Aim: To assess the radiation dose received in a clinical/real life setting by patients visiting selected radiological centres in Enugu, Enugu State, southeast of Nigeria for diagnostic computed tomography (CT) scans of the heads and thus assess compliance to the diagnostic reference levels (DRL). Study Design: A prospective cross-sectional survey design. Place and Duration of Study: CT Units of University of Nigeria Teaching Hospital, Memfys Hospital for Neurosurgery and Conquest Medical Imaging Limited in Enugu, Enugu State, Nigeria between April 2012 and January 2013. Materials and Method: Radiation doses absorbed by 98 patients (60 males and 38 females, age range 3-65years) that presented for CT scans of the head at the study centres were prospectively measured using lithium fluoride thermoluminescent dosimeter, LiF-TLD (TLD-100) chips. The mean absorbed dose, mean effective dose, collective dose and the per caput dose with their standard deviations were obtained. Results: The mean absorbed dose was 4.315 ± 3.815mSv (range 1.005-17.607mSv) and the mean effective dose was 2.244±1.984 mSv. In children (0-15years) the mean absorbed dose was 5.604±4.904mSv and mean effective dose, 2.914±2.278 mSv and these doses were higher than that of the adults. The annual collective dose was 224.40±198.4 person-mSv and the annual per caput dose was 5.9 x 10-7mSv. The calculated mean organ effective doses were 0.147±0.056mSv, 0.884±0.334mSv, 0.147±0.056mSv, 0.3540±0.134mSv and 0.147±0.056mSv for the brain, eye lenses, thyroid gland, red bone marrow and breast respectively. Conclusion: TLD chip were used to assess patients’ radiation dose in a clinical setting. The overall mean effective dose (2.244mSv) was in compliance with the recommended DRL. The radiation dose received correlated positively with the tube current (mA) and number of images obtained but negatively with the scan time, patients’ head AP dimension and age. Radiation risks from CT can be reduced through justification of the procedure and dose optimization.

Experimental determination of dosimetry parameters for Sinko 125I seed source using thermoluminescent dosimeter / 中华放射肿瘤学杂志

Objective To study the dosimetry parameters of 125I seed source (type Sinko BT-125-1) with thermoluminescent dosimeter (TLD) in the phantom.Methods The new type of phantom was modified to suit to measurement of a common type of 125I seed source.The AAPM TG43 protocol recommended measurements of dose-rate constant (Λ),radial dose function (gL (r)),and anisotropy function (F (r,θ)) have been performed in the phantom with TLD.Results The Λ was 0.928 cGyh-1 U-1.The gL(r) was determined at different radial distances r ranging from 1.0 to 10.0 cm with an interval of 1.0 cm ; and F (r,θ) at angles from 0° to 90° in 10° increments.The gL (r) of 125I seed source showed a difference of 9.6％ at the most in comparison to the corresponding values of 125I seed source (type Amersham 6711).The difference in F(2 cm,θ) of 125I seed source and Amersham 6711 was up to 10.2％ near the source end.With the phantom the combined standard uncertainty in the whole measurement was less than 6.0％.Conclusions The experimental results exhibit fairly small measurement uncertainties and good self-consistency.It's feasible to measure the dosimetry characters of permanent implant seeds in the modified phantom.

Dosimetric verification for radiotherapy quality audit under reference and non-reference conditions in Jiangsu province / 中华放射医学与防护杂志

Objective To verify the methodology for auditing dosimetric parameters in reference and non-reference conditions with thermoluminescent dosimeters (TLDs).Methods Under reference and non-reference conditions,the established TLD methods were used to observe the absorbed dose variations with depth,SSD,field size and 45 wedges for 10 photon beams at 5 hospitals.Dosimetric parameters,including doses at Dmax points in axis,on 5 electron beams of 9 MeV were measured.The measurement results were compared between the TLDs and plane parallel ionization chambers.Results For 6 MV photon beams,the relative deviation of between finger ionization chamber method and TLD chips was in the range of-1.7％ to 5.4％ under on-axis non-reference conditions,and-6.3％ to-0.6％ under off-axis non-reference conditions,respectively,all within the range of ≤ ± 7％ as required by the IAEA.The relative deviation between plane parallel chamber and TLD method was-2.3％ to 3.7％,within ± 5％ as required by the IAEA.Conclusions It is convenient and feasible to use TLD method for quality audits of dosimetric parameters in radiotherapy.

Verification of Skin Dose in Tomotherapy Using the Developed Phantom for Image Based Radiation Treatment System / 의학물리

Radiation treatment for skin cancer has recently increased in tomotherapy. It was reported that required dose could be delivered with homogeneous dose distribution to the target without field matching using electron and photon beam. Therapeutic beam of tomotherapy, however, has several different physical characteristic and irradiation of helical beam is involved in the mechanically dynamic factors. Thus verification of skin dose is requisite using independent tools with additional verification method. Modified phantom for dose measurement was developed and skin dose verification was performed using inserted thermoluminescent dosimeters (TLDs) and GafChromic EBT films. As the homogeneous dose was delivered to the region including surface and 6 mm depth, measured dose using films showed about average 2% lower dose than calculated one in treatment planning system. Region indicating about 14% higher and lower absorbed dose was verified on measured dose distribution. Uniformity of dose distribution on films decreased as compared with that of calculated results. Dose variation affected by inhomogeneous material, Teflon, little showed. In regard to the measured dose and its distribution in tomotherapy, verification of skin dose through measurement is required before the radiation treatment for the target located at the curved surface or superficial depth.

Dosimetric analysis of persons accompanying nuclear medicine patients in the therapeutic room / Análise dosimétrica de acompanhantes de pacientes de medicina nuclear internados em quarto terapêutico

OBJETIVO: Este trabalho avaliou doses recebidas por acompanhantes que compartilharam o mesmo quarto terapêutico com pacientes tratados com câncer de tireóide ingerindo iodo-131 (131I) e comparou os resultados obtidos aos limites determinados pelas normas brasileiras de radioproteção. MATERIAIS E MÉTODOS: Avaliaram-se seis grupos de pessoas. Cada grupo foi formado por um acompanhante e um paciente, que compartilharam o mesmo quarto terapêutico. Realizaram-se, também, 23 outros experimentos, sendo que nestes um simulador foi usado em substituição à segunda pessoa no quarto terapêutico. As atividades de 131I administradas aos pacientes foram de 3.700 MBq ou 5.550 MBq. Dosímetros termoluminescentes na forma de pó, fluoreto de lítio dopado com magnésio, titânio e sódio foram usados para a avaliação das doses. RESULTADOS: Os resultados mostraram que uma pessoa que compartilha o mesmo quarto terapêutico, durante dois dias, com um paciente tratado com 3.700 MBq ou 5.550 MBq de 131I, seguindo as orientações de radioproteção fornecidas pela equipe médica, é exposta a uma dose média de (0,51 ± 0,02) mSv, para um nível de confiança de 99 por cento. CONCLUSÃO: De acordo com as normas brasileiras, do ponto de vista da radioproteção, não há impedimento acompanhar um paciente de medicina nuclear durante esse tratamento.

OBJECTIVE: The present study evaluated the doses received by companions who had shared therapeutic rooms with patients undergoing treatment with 131-iodine (131I). The results were compared with the limits established by the Brazilian radiation protection regulatory standard. MATERIALS AND METHODS: Six pairs of persons (a patient and a companion sharing a same therapeutic room) were evaluated. Still, other 23 experiments were accomplished with a phantom replacing the companion. The therapeutic 131I activities given to the patients corresponded to 3700 MBq or 5550 MBq. Powdered lithium fluoride thermoluminescent dosimeters doped with magnesium, titanium and sodium were utilized for evaluating the doses. RESULTS: The results demonstrate that a person sharing a same therapeutic room, for two days, with a patient who had been given 3700 MBq or 5550 MBq of 131I, according to radioprotection recommendations, is exposed to a mean dose of (0.51 ± 0.02) mSv for a 99 percent confidence level. CONCLUSION: According to the Brazilian radiation protection standards there is no impediment for a person to accompany a nuclear medicine patient who has been given 3700 MBq or 5550 MBq of 131I during the patient stay in the therapeutic room.

In vivo and in vitro Confirmation of Dose Homogeneity in Total Body Irradiation with Thermoluminescent Dosimeter / 대한방사선종양학회지

PURPOSE: Total body irradiation (TBI) or whole body irradiation is used to acquire immune suppression, to treat malignant lymphoma and leukemia, and as an conditioning regimen for bone marrow transplantation. For these purposes, many methods were developed to obtain homogenous dose distribution. The objective of this study was to analyze and confirm the accuracy and the homogeneity of the treatment setup, the parallel opposed lateral technique, currently used in Seoul National University Hospital. MATERIALS AND METHODS: Surface dose data, measured with a thermoluminescent dosimeter, of 8 patients among 10 patients, who were given total body irradiation with the parallel opposed lateral technique between September 1996 to August 1998, at Seoul National University Hospital were analyzed. Surface doses were measured at the head, neck, axilla, thigh, and ankle level. Surface and midline doses were measured with similar set-up and technique in the Humanoid phantom. RESULTS: Measured surface doses relative to prescribed dose for the head, neck, axilla, thigh, and ankle level were 91.3+/-7.8, 98.3+/-7.5, 95.1+/-6.3, 98.3+/-5.5, and 95.3+/-6.3%, respectively. The midline doses of the head, neck, axilla, thigh, and ankle level estimated from the surface-to-midline ratios in the Humanoid phantom were 103.4+/-9.0, 107.8+/-10.5, 91.1+/-6.1, 93.8+/-4.5, and 104.5+/-9.3%, respectively. Measured surface doses and estimated midline doses ranged from -8.9% to + 7.8%. Midline doses at the neck and the axilla level deviated more than 5% from the prescribed doses. The difference of the estimated midline doses at the neck and the axilla level and the actual doses were attributed to the thickness differences between the Humanoid phantom and the patients. CONCLUSION: Distribution of the midline doses as well as the surface doses were measured to be within -8.7 - +7.8% range. Actual dose distribution in the patient is expected to be better than the measured dose range mainly attributed to thickness difference between the patient and the Humanoid phantom.