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For some special radiation practices, such as working with radioisotopes in the nuclear medicine department, hand exposure is inevitable and usually results in high radiation doses. Therefore, ring dosimeters are frequently worn on the finger to monitor the does to the hand (extremity). Most current commercial ring dosimeters are thermoluminescence type and consist of a single dosimetry chip; they do not have the ability to discern the energy of radiation. This study developed a new optically stimulated luminescence (OSL) ring dosimeter. Each OSL ring dosimeter consists of two OSL chips, one cast, one ring holder, and one ring clip. A dose algorithm was also designed to calculate the dose with correction for energy dependence. The new OSL ring dosimeter and algorithm were validated using blind tests under irradiation from X-ray, gamma ray, and beta in the National Radiation Standard Laboratory at the Institute of Nuclear Energy Research in Taiwan. The newly designed OSL ring dosimeter and algorithm could pass the blind test following American National Standards Institute/Health Physics Society standard N13.32–2008 from category I to III. For category IV, the feasibility was confirmed under assumptions specific to this study. The reproducibility and lower limit of detection of this system were also represented in this study.

The International Commission on Radiological Protection (ICRP) recommended that the equivalent dose limit for the lens of the eye be decreased from 150 mSv/y ( ICRP, 2007 ) to 20 mSv/y averaged over five years ( ICRP, 2011 ). How to accurately measure the eye-lens dose has, therefore, been an issue of interest recently. Interventional radiologists are at a higher risk of radiation-induced eye injury, such as cataracts, than all other occupational radiation workers. The main objective of this study is to investigate the relationship between the doses to the eye lenses of interventional radiologists measured by different commercial eye-lens dosimeters. This study measured a reference eye-lens dose, which involved placing thermoluminescent dosimeter (TLD) chips at the surface of the eye of the Rando Phantom, and the TLD chips were covered by a 3-mm-thick tissue-equivalent bolus. Commercial eye-lens dosimeters, such as a headband dosimeter and standard personnel dose badges, were placed at the positions recommended by the manufacturers. The results show that the personnel dose badge is not an appropriate dosimeter for evaluating eye-lens dose. Dose deviations for different dosimeters are discussed and presented in this study.

Urolithiasis is a common disease; patients suspected of suffering from urolithiasis will be examined by abdomen x-ray, Sono, Intraudio Videonous Urography (IVU) and Computed Tomography (CT). The detection rates for calculus in above examinations are respectively: 50–70% (x-ray), 50–60% (Sono), 70–90% (IVU) and 97% (CT). In addition, the effective doses are respectively: 0.63 mSv (x-ray), no radiation dose (Sono), 2.6 mSv (IVU) and 8–16 mSv (CT). Although CT has the highest detection rate for calculus, it also has the highest radiation dose. This research sought to lower the radiation dose by using CT scans with different dose conditions of standard dose (SD), 50% SD, 25% SD, and 15% SD to diagnose patients who suffer from urolithiasis and thus explore the feasibility of examining urolithiasis via CT with lower dose conditions. This research simulated the examination of patients with RANDO phantom, collocating PMMA slice phantom and pig's kidney. Fake calculuses made of five different materials of different sizes were put into the phantom and scanned individually. The results of the scanned images were given to two physicians who had many years of diagnostic experience to interpret the urolithiasis images. This study explored the different image qualities of CT with different dose conditions. In addition, this research used thermoluminescent dosimeters (TLD) to measure the radiation doses and compared the results with the dose values shown on the screen of the CT scanner to estimate the dose conversion factor (k). The research results showed that a low-dose CT was able to provide good image quality and thus have a lower radiation dose. Therefore, a low-dose CT is suggested the main examination method to diagnose patients with urolithiasis.

Modern dental X-ray examination that consists of traditional form, panorama, and cone-beamed 3D technologies is one of the most frequent diagnostic applications nowadays. This study used the Rando Phantom and thermoluminescence dosimeters (TLD) to measure the absorbed doses of radiosensitive organs recommended by International Commission on Radiological Protection (ICRP), and whole body effective doses which were delivered due to dental X-ray examination performed with different types of X-ray instrument. Besides, enamel samples which performed reading with Electronic Paramagnetic Resonance (EPR) procedure were also used to estimate the tooth doses. EPR is a dose reconstruction method of measuring free radicals induced by radiation exposure to the calcified tissue (mainly in the tooth enamel or bone) to evaluate the accepted high dose. The tooth doses estimated by TLD and EPR methods were compared. Relationships between the tooth doses and effective doses by dental X-ray examinations with different types of X-ray equipment were investigated in this work.

The quality assurance of digital mammogram has been included in the Standards of Medical Exposure Quality Assurance in Taiwan since July, 2008. According to the Standards, determination of the half-value layer (HVL) is an integral part of mammographic dosimetry which requires the evaluation of patient's glandular dose. The purpose of this study was to develop a simple method to help hospitals determine the HVL. A compact device, accommodating Harshaw TLD-100H (LiF:Mg,Cu,P) chips and aluminum sheets in a small holder, was designed to determine the HVL under clinical exposure conditions (tube voltage, target/filter) of a digital mammographic unit. This device was used to determine the HVL ranging from 0.3- to 0.5-mm Al. Air KERMA measured by the TLDs were corrected for scatter radiation and energy dependence caused by the aluminum sheets. Once scatter and energy dependence were corrected, the agreement of determined HVLs was within ±7% with measured data using the ionization chamber. This device provides a simple, inexpensive and remote means to reliably audit the HVL of a mammography unit on a periodic basis.

The Cyclotron Center in Shin Kong Wu Ho-Su Memorial Hospital (SK Cyclotron Center) produced the 18 F-FDG compound and provided it to the Positron Emission Tomography (PET) center for diagnosis services. The works in SK Cyclotron Center are distinguished into three procedures including production, dispensation, and carry of the compound. As the medical cyclotron was operated to produce the radioactive compounds, secondary radiations such as neutrons and γ -rays were also induced. To estimate the exposure for the staffs working in the SK Cyclotron Center, the dual-TLD (TLD-600/700) chips were used to measure the doses contributed from photons and neutrons during the operation of the cyclotron, and the doses contributed from photons during dispensation and carry of the nuclear compounds. In the results, the mean H p (10) and H p (0.07) of the finger for a worker were 2.11 mSv y −1 and 96.19 mSv y −1 , respectively. Results estimated by the regular personal chest badges and finger ring dosimeters which considered only the doses of photons were compared. By means of the results of this work, doses contributed from different working procedures and from different types of radiation to the workers in the SK Cyclotron Center were realized.

This paper discussed the neutron doses induced by the high energy medical linear accelerator (Linac). Thermoluminescent dosimeter (TLD) pairs are usually chosen to distinguish the doses of neutrons from photons in mixed radiation field. In this work, TLD-600 and TLD-700 chips were used to investigate the dose contributions of neutrons induced by 15 MV photon beam of the medical Linac used in radiotherapy. A Rando phantom filled with these dual-TLD chips was irradiated in the 15 MV photon beam to assess the doses contribution of the induced neutrons. Besides, dual-TLD chips were also placed in the treatment room to estimate the spatial dose distribution of neutrons. In the results, dose contributions of neutrons in phantom are less than 0.1% compared with the maximum dose of photons. The dose distribution of neutrons in the treatment room was also revealed.

In radiodiagnosis, optimization is defined as a method of reducing the patient-absorbed doses without affecting image quality. In this study, we aimed to determine the parameters of a multi-slice CT (MSCT) scanner (LightSpeed VCT 64; General Electric) that ensure the least organ dose with the best image quality (i.e., optimization) for chest examinations, which are the most frequently used radio diagnostic investigations. Organ doses of an anthropomorphic phantom were measured during MSCT chest scans by using GR-100 (LiF: Mg, Ti) thermo-luminescent dosimeters (TLDs) attached to various parts of the organs. The accumulated equivalent doses were calculated to evaluate the radiation risk to sensitive organs by using different scan conditions and measuring the absorbed doses, because different scan parameters (e.g., pitch, tube current, scan type, etc.) may affect the dose contribution to these organs. By means of the radiation and tissue weighting factors recommended in the International Commission on Radiological Protection (ICRP) 103 report, the effective dose was then estimated. The pitch value and tube current were the main parameters affecting the organ doses of the phantom: increase in the pitch value and reduction of the tube current decreased the absorbed doses without impacting the image resolution and diagnostic information. Consequently, radiologists can establish an optimization protocol in MSCT and acquire high-resolution images with adequate diagnostic information while using the lowest exposure dose for chest examinations.