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).

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.

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.

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.