International Journal of Radiation Research
Volume:18 Issue: 1, Jan 2020

This research focuses on study of natural radioactivity (226Ra (238U), 232Th, 40Kand 222Rn) in different types of water samples at Al-Hurrah City in Najaf province/Iraq using NaI (Tl) and RAD-7 detector.

Samples have been collected from three major sources of water, City Water (Drinking Water), River Water and Underground Water. The daily consumption of these three sources by humans in construction materials determines the standards used to measure the Radiological Contamination in these sources such as Annual Effective Dose, Radium Equivalent, Absorbed Dose rate, External Hazard Indexes, Internal Hazard Indexes and Activity Concentration Index Due to Gamma Ray of long-live Radioisotopes.

The results show that the average of Radioactivity Concentration forRadium-232 were 1.84±0.39Bq/L, 2.31±0.43Bq/Land 7.15±1.88Bq/L, for Thorium-232 were 1.31±0.33Bq/L, 0.98±0.13Bq/Land 2.19±0.44Bq/L, for Potasium-40 were 9.07±1.32Bq/L, 22.29±2.93Bq/Land 40.89±8.93Bq/L and for Radon-222 were 35.5±0.00 mBq/L, 355.50±30.33 mBq/L and 712.00±97.20 mBq/L. Based on Gamma Radionuclides measurement, the mean annual effective doses of city water and river water are lower than the reference level of the effective dose recommended by the ICRP, while the mean annual effective doses of underground water were higher than the reference level of the effective dose recommended by the ICRP.  

Finally, the researcher found that all the radiological parameters such as Raeq, D, Hex, Hin and Iγ in the water samples were within the range the global limit, thus it’s safe to use in construction materials.

A non-rigid cervical magnetic resonance (MR) image registration algorithm combining pixel intensity and local region gradient features was proposed in this study for cervical cancer radiation therapy (RT) evaluation.

The method was based on the following main steps: (1) each patient was scanned 2 times. The first scan was before internal-beam RT, and second scan was about 3~4 weeks after internal-beam RT. (2) DoG salient points mixed with stochastically sampled points were used as keypoints, and pixel intensity and PCA-SIFT features around them were extracted to build a feature vector for each keypoint. (3) In non-rigid registration process, α-mutual information (α-MI) was used as similarity measure. The method was evaluated by 20 MR images acquired from 10 patients with biopsy-proven squamous cell carcinomas.

For cervical cancer, the deformation of tumor and organ between different MR image acquisitions was subject to several errors, including possible mechanical misalignment, respiratory and cardiac motion, involuntary and voluntary patient motion, bladder and bowel filling differences. To minimize these ambiguities, patients filled their bladder before scanning. The proposed hybrid features can effectively catch the bladder and bowel in MR images, and α-mutual information (α-MI) based non-rigid registration can effectively align two long time internal MR images.

Non-rigid cervical MR image registration method using hybrid features on α-MI can effectively capture different tissues in cervical MR images. Accurately aligned MR images can assist cervical cancer RT evaluation process.

Physical agents, such as ultrasound, can promote functional restoration and regenerative processes of the peripheral nervous system. However, little is known about the effects of X-ray radiation on nerve regeneration after peripheral nerve injury. The aim of the present study was to investigate the effects of various doses of X-ray radiation on nerve regeneration after sciatic nerve injury in rats.

The sciatic nerves of Sprague-Dawley rats were transected and repaired via epineurium end-to-end neurorrhaphy. Eighty rats each received single and local X-ray doses of 0 Gy, 0.2 Gy, 1 Gy, 7 Gy and 14 Gy. Functional and morphological assessments of the process of nerve regeneration were performed by using various measurement tools.

Compared with the 0 Gy, 0.2 Gy and 14 Gy groups, the 1 Gy and 7 Gy radiation groups experienced significantly increased sciatic functional index, motor nerve conductive velocity (MNCV), expression of S-100, mean diameter of axons, and thickness of myelin sheaths and decreased perineural scar tissue. There were no differences between the 1 Gy group and the 7 Gy group or between the 0 Gy group, the 0.2 Gy group and the 14 Gy group with the exception of MNCV and the expression level of S-100.

X-ray radiation in doses of 1 Gy and 7 Gy promoted nerve regeneration after sciatic nerve injury in a rat model. The dose of 14 Gy exerted inhibitory effects, and 0.2 Gy exerted no significant effect on nerve regeneration.

The aim of this study was to compare the dosimetric and radiobiological efficiency of various intensity modulated radiotherapy (IMRT) techniques with 3D conventional radiotherapy (3D-CRT) technique in the treatment of early stage oral tongue cancer.

This study was performed on 38 CT images of patients who were planned with 3D-CRT and three sets of IMRT treatment plans including five, seven and nine fields with prescribed dose of 66 Gy to planning target volume. The dose volume histograms, homogeneity index (HI), conformity index (CI) and normal tissue complication probability (NTCP) of main organs at risk were derived using Prowess Panther treatment planning system.

The results of this study indicated an increase in HI and CI for IMRT plans compared to 3D-CRT. Furthermore, IMRT techniques led to a statistically significant reduction in received dose by mandible (up to 10.10 Gy) and thyroid (up to 13.59 Gy) compared to the conventional technique used; whereas, it led to a statistically significant increase in received dose by parotid glands (up to 7.62 Gy) and brain stem (up to 9.87 Gy). In addition, IMRT increased (up to 12.79%) the probability of occurrence of parotid xerostomia and decreased mandibular complications (up to 7.76%) in comparison to conventional treatment.

It can be concluded that IMRT can be more successful in improving oral tongue cancer treatment with more conformity and homogeneity. However, IMRT may not be required for all patients with oral tongue cancer at early stage of the disease.

Ginger (Zingiber officinale), a member of the Zingiberaceae family that contains phenolic compounds such as gingerol, paradol, zingerone, zingiberol and shogaols, has antioxidant, anti-inflammatory, antimicrobial, antifungal and antitumour activity. Materials: The present investigation was intended to evaluate the radioprotective effects of ginger extract in Wistar albino rats against whole-body gamma-ray irradiation. Rats were orally administered 250 mg/kg b.w. of ginger extract by gavage for 14 consecutive days. On the 14th day, 2 hr after the last ginger administration, the animals were exposed to whole-body gamma-rays of 6 Gy. The radioprotective potential of ginger was assessed through measurement of the DNA oxidative stress marker 8-hydroxy-2’-deoxyguanosine in serum, analysis of chromosomal abnormalities and micronucleus formation in bone marrow cells and estimation of DNA impairment in both bone marrow cells and epidydimal sperm using comet assay. Sperm DNA integrity and sperm shape abnormalities were also studied.

The results revealed that ginger extract reduced DNA oxidation by restoring the levels of 8-hydroxy-2’-deoxyguanosine in serum. Ginger also significantly reduced radiation-induced chromosomal abnormality and micronucleus formation. Additionally, pretreatment with ginger extract significantly decreased DNA damage in both bone marrow cells and epididymal sperm, maintained sperm DNA integrity and reduced the occurrence of sperm anomalies after irradiation.

Our results confirmed that ginger extract offers rats significant protection against whole-body gamma-rays and helps to alleviate the effects of radiation. Our findings suggest a new strategy to combat the effects of acute radiation doses that impair biological systems.

Melatonin is a natural antioxidant that is produced by the pineal gland. In this study was evaluated antioxidant and possible protective effects of melatonin on frequency of micronucleus (MN) formation in human cell lines exposed to γ-radiation.

To achieve the best concentration for antioxidant activity of melatonin DPPH (1,1-diphenyl-2-picrylhydrazyl) assay was used. Hela and MRC5 cells were cultured and treated with optimum concentration of melatonin (1200μg/ml). After 2h, cells were exposed to 2Gy-gamma ray. For each cell group, one flask was considered as control. Immediately after irradiation, cells were exposed to cytochalasin B to arrest cells at cytokinesis. Then the frequency of MN induced by radiation alone or in the presence of melatonin was evaluated. 

By DPPH assay, the optimum concentration of melatonin for its antioxidant activity was determined 1200μg/ml. Our results showed that the frequency of micronuclei increased in irradiated cells compared to the control groups (p<0.05). Conversely, pre-treatment of cells with melatonin significantly reduced the number of MN produced both in MRC5 and Hela cells (p<0.05).

Results indicated that γ-radiation induced MN in the cells. The protective effect was achieved when melatonin was present in the cellular environment pre-irradiation. Indeed, melatonin with scavenging and antioxidant ability neutralizes toxic reactants and stimulates DNA repair pathways. Moreover, the results indicate that protective effect of melatonin is higher in MRC5 cells than in Hela cells. Therefore, it can be concluded that other mechanisms such as induction of cell cycle arrest by melatonin might be exist only in MRC5 cells. However, the radio-protective mechanism of melatonin is not clearly known.

X-ray chest fluoroscopy is a compulsory component of the health examination procedure in China. The radiation dose from chest fluoroscopy is the largest in X-ray examination. More than half of the women in their twenties with breast cancer have been given X-ray fluoroscopy. Studies have shown that Caveolin-1 is involved in the repair of damage DNA in tumor cells induced by irradiation. However the mechanism and role of Caveolin-1 in normal human mammary epithelial cells are not clear. 

Here, normal human mammary epithelial cells (MCF10A) and the cells with Caveolin-1 knockdown (MCF10ACE) were exposed to X-ray radiation to investigate the role of Caveolin-1 in the enhancement of radiosensitivity in these cells and the associated mechanism.

Decreased survival rate and a significantly higher level of cell arrest at the G1 and G2 phases, as well as reduced activation of the DNA damage repair proteins ATM and p53, and the stress protein p38MAPK were manifested by MCF10ACE cells compared to MCF10A cells, following exposure to X-ray radiation. Furthermore, binding between Caveolin-1 and Mdm2 in MCF10ACE cells was also lower than in MCF10A cells.

Overall, the finding indicated that Caveolin-1 played an important role in decreasing the radiosensitivity of human mammary epithelial cells.

Breast cancer is considered as one of the most influential diseases around the world. Radiation is one of many ways that is being use to against cancer. However, patients treated with radiation may face cancer recurrence. Some plant compounds exhibit antioxidant effects. Sinensetin is a methylated flavone present in citrus and Orthosiphon stamineus. In this study, we examined the role of sinensetin in increasing the radiation sensitivity.

The cytotoxic effect of sinensetin was evaluated in MDA-MB-231 by MTT assay. Additionally, the clonogenic ability of cells was evaluated in the presence of sinensetin. Real-Time PCR was performed to detect and quantify expression profiles of apoptosis related genes.

Sinensetin decreased the viability of MDA-MB-231 in a concentration and time dependent manner. The survival fraction was decreased in cells treated with sinensetin prior to X-irradiation compared to cells treated with X-ray only. Furthermore, treatment of cells with sinensetin and X-ray could increase expression level of p53, Bcl-2 and STAT3.

According to the results, sinensetin combined with X-ray can induce apoptosis in the treated cells.

Ionizing-radiation induces oxidative stress and thyroid toxicity. Thyroid function disorders have a great impact on fertility in both sexes.

Forty female rats were divided into four groups. Control, Spirulina-treated (300 mg/kg); given orally for 15 days, γ-irradiated; given (5 Gy whole body γ-rays) and Spirulina+irradiated; given Spirulina for 15 days before irradiation. Animals were sacrificed the 3rd day post-irradiation. The level of the oxidant/antioxidant markers: Malondialdehyde (MDA), superoxide dismutase (SOD), catalase (CAT) and glutathione peroxidase (GSH-Px) was evaluated. In addition, caspase-3 activity was measured as apoptotic marker and comet assay to detect DNA-damage. Serum thyroid stimulating hormone (TSH), triiodothyronine (T3) and thyroxine (T4) were determined to evaluate the thyroid function alterations. Also, analysis of reproductive hormones; follicle stimulating hormone (FSH), luteinizing hormone (LH), estradiol (E2) and progesterone (P4) was detected. 

Whole body γ-irradiation-induced oxidative stress, denoted by significant decreases of antioxidant markers and an increase in MDA content. The activity of caspase-3 was significantly increased and comet assay revealed DNA damage. Also, serum level of TSH was significantly increased, while T3, and T4, significantly decreased in irradiated rats. Moreover, the reproductive hormones showed significant decreases. Spirulina treatment has significantly attenuated oxidative stress in thyroid tissues, decreased caspase-3 activity and ameliorated DNA damage, concomitant with significant amelioration in the levels of thyroid and reproductive hormones.

Spirulina may alleviate γ-rays-induced thyroid damage and play a significant role in the regulation of thyroid and reproductive hormones in female rats.

In three dimensional conformal radiotherapy (3D-CRT), treatment planning is based on computerized tomography (CT) images. However, the data obtained from CT may not be sufficient in target delination. The purpose of this study is to show the differences between the radiotherapy (RT) plans which were done with positron emission tomography (PET) fusion or not.

Patients with lung cancer between February 2009 and January 2012 at our institution were assessed retrospectively. Sixty patients who were treated with 3DCRT, CT simulation images were registrated with PET images. For each patient target volumes were determined and normal tissues were revised. Wilcoxon Signed Rank Test was used to compare the two groups.

For gross tumor volume (GTV), clinical target volume (CTV) and planning target volume (PTV); median volume values, median mean dose values and median maximum dose values were significantly different according to use of PET. About normal tissue doses; mean lung dose (MLD), lung V20, mean and maximum esophagus dose, V50 and V60, mean heart dose and maximum medulla spinalis dose were analyzed.

Within these parameters there were statistically significant difference except in maximum dose of esophagus and V60. In our study, we observed decreased target volumes and higher dose distrubutions for target volumes in PET registrated RT plans. According to these data, it is possible to say that optimal RT plans can be formed for lung cancer by using PET registration.

In Southeast Europe medical accelerators are sometimes placed in small vaults originally built for 60Co treatment unit. In order to meet shielding requirements for high energy photon beams, the wall thickness had to be increased. Since the vaults are already limited in size, instead of adding more concrete, materials with high-Z elements were used. Limited vault size and addition of high-Z elements can contribute to the neutron dose equivalent for both medical personnel and patients.

The most commonly used empirical equations for estimation of neutron dose equivalent at the maze door in the vault are by Kersey and Wu-McGinley. In order to assess accuracy of these equations, Monte Carlo (MC) simulations of various geometrical and compositional changes of vault were conducted. Neutron ambient dose equivalent (H*n(10)) was observed when dimensions of the vault walls were reduced gradually.

The empirical equations gave results with reasonable accuracy when vaults were of standard size. When the vault was decreased to the size of the usual 60Co unit vault, the most commonly used equations showed significant difference in results (up to 90%) in comparison to MC simulations. MC simulations showed that introducing different materials in shielding can change the neutron dose equivalent in vicinity of accelerators.

For vaults limited in size, new simplified equation for neutron dose equivalent at the maze doors is presented, although performing a MC simulation of the specific vault is suggested.

Pentraxins (PTX) play key roles in innate immunity and inflammatory responses. An increase in PTX3 levels may be a marker of early radiation injury in the lung. Thus, we aimed to determine the effect of radiation on PTX3 expression in a lung injury mouse model.

Twenty-four 6–8-week-old mice were divided into 4 groups, one control (group 1) and three experimental groups (groups 2–4) irradiated with 6 MV photons and 5 Gy in a single fraction. Groups 2, 3, and 4 were sedated and euthanized 24, 72, and 168 h after radiation, respectively. The right lung middle lobe was then removed for histochemical examination and immunostaining for PTX3 expression, which was evaluated semi-quantitatively using H-SCORE analysis. Kolmogorov-Smirnov and Kruskal Wallis one-way analysis of variance were used for statistical analysis.

Immunohistochemistry of lung tissue samples showed different PTX3 expression levels across the four groups. Group 1 showed weak staining (232.50 ± 9.501), while group 2 (301.50 ± 7.472) and group 3 (283.50 ± 7.090) showed strong immunoreactivity. Group 4 showed moderate PTX3 immunoreactivity (271.50 ± 10.013). Moreover, H-score values between control and early radiation groups were statistically significant (group 1 vs. group 2, p < 0.001; group 1 vs. group 3, p = 0.002).

PTX3 levels may be an early marker for long-term radiation effects. Our study provides insights into the pathological processes of pulmonary inflammation and acute radiation injury, and may provide novel therapeutic strategies for controlling pulmonary inflammation without eliciting radiation injury.

The use of radiation therapy for medulloblastoma can affect children’s visual system. We estimated children’s visual system complication probability in the craniospinal irradiation (CSI) technique with three-dimensional conformal radiotherapy (3D-CRT).

CSI of fifteen medulloblastoma patients and a phantom were planned with 6 MV photon beams and 23.4 Gy prescribed dose. The doses of lenses were measured using thermoluminescence dosimeters (TLD). The delivered doses and complication probabilities were calculated based on the equivalent uniform dose (EUD) model to each contoured organ, including the bilateral lenses, optic nerves, retinas and optic chiasm.

The received dose for each organ was less than the tolerance value (p<0.001), except for the eye lens. The normal tissue complication probability (NTCP) values for all of the organs at risk (OAR) were found insignificant. The discrepancies of calculated and measured doses for the right and left lenses were 6.35% and 6.23% (p<0.001), respectively.

The results of this study showed based on the International Commission on Radiological Protection (ICRP) publication 118 that children with medulloblastoma cancer treated with CSI with 3D-CRT method are susceptible to cataract complication.

Osteoporosis is a progressive systematic skeletal illness characterized by low bone mineral density (BMD), deterioration of microarchitecture of bone tissues and susceptibility to fracture caused by bone resorption. The study investigates the possible role of Alfacalcidol; vitamin D (Vit D) to mitigate osteoporosis induced by corticosteroid and γ-rays in rats.

Eighty Sprague-Dawley rats were divided equally into eight groups: Control group (1 ml olive oil orally), Epirelefan group (7mg/kg sc), Vit D group (20,000 IU/kg orally), Vit D plus Epirelefan group, Vit D plus γ-rays (8 Gy) group, Epirelefan plus γ-rays group, Vit D plus Epirelefan plus γ-rays group and γ-rays groups.

In Epirelefan group, mandible bone has small cavities, micro fissures, thinning and decrease in the number of trabecular, which may appear rod-like and concave beside increase marrow cavities. In Epirelefan + γ-rays group, the lesions were more severe with increasing osteoclast and alteration of serum calcium, phosphate and alkaline phosphatase. The administration of Vit D before corticosteroid injection and pre γ-rays-irradiation has significantly reduced mandibular damage.

Vit D could be efficient in mitigating osteoporosis occurred by corticosteroid and γ-rays in rat model.

Radiofrequency electromagnetic radiation (RF-EMR) of mobile phone has adverse effects on human health, such as the liver tissue. Melatonin, as a neurohormone has antioxidant property. The aim of present study was to evaluate the protective effects of melatonin on liver damage induced by mobile phone-radiofrequency radiation. Matherials and

In this experimental study, 32 adult male BALB/c mice were divided randomly into four groups: control group (received only normal saline), melatonin group (2 mg/kg, for 30 consecutive days, intraperitoneally), Electromagnetic radiofrequency radiations (RF-EMR) group (4 hours per day for 30 consecutive days, whole body), and melatonin + RF-EMR) group (melatonin was prescribed one hour before exposure to RF-EMR. One day after treatment period were evaluated oxidative stress parameters, serum biochemical, and histopathological assays of liver.

The results exhibited that RF-EMR significantly increased oxidative stress (increased Malondialdehyde and decreased Glutathione level) compared with control and melatonin group (P < 0.001). Histopathological findings in the RF-EMR group showed periportal leucocyte infiltration, dilation of sinusoids, necrosis, vacuolation, and granulomatous formation. Also, alanine transaminase and aspartate transaminase, alkaline phosphatase in serum increased significantly compared with control and melatonin groups (P<0.001). Melatonin administration significantly reduced oxidative stress (P<0.01) in the radiated mice and ameliorated histopathological compared with control group.

The data indicate that RF-EMR induces oxidative damage and changes histopathological structure in the liver. Melatonin decreased oxidative stress and improved the liver damage induced by RF-EMR.

Indoor levels of 222Rn in some residential areas in Ramsar are as high as 31,000 Bq/m3, resulting in mean internal exposures up to 71 mSv/y. The main goal of this study was to develop a simple mathematical model for predicting radon concentrationfrom gamma radiation level in dwellings located in high background radiation areas (HBRAs) and a nearby normal background radiation area (NBRA) of Ramsar.

The levels of gamma background radiation and indoor radon were measured in 350 dwellings located in normal and high background radiation areas (210 dwellings from HBRAs and 140 dwellings from NBRAs). Moreover, data about the most important environmental factors such as temperature and humidity as well as the inhabitants’ nutrition were collected.

The mathematical relationship between the gamma radiation level and indoor radon concentration in NBRAs and HBRAs is introduced in this study. The findings obtained in this study clearly indicate that in normal and high background radiation areas of Ramsar the majority of confounding factors such as the type of building materials and ventilation in different houses are almost identical. Therefore, the level of gamma radiation can be used as a strong predictive tool for radon concentration.

As radon concentration in indoor air strongly varies with time, the simple mathematical methods developed in this study, can help health physicists and environmental scientists have an estimate of the mean radon level in these areas.

Management of head and neck cancer includes surgical resection, chemotherapy and radiotherapy (RT). We hypothesized that pre-radiation treatment with a mineralocorticoid receptor (MR) antagonist, spironolactone (S), may have radioprotective effect on salivary glands.

Study included 30 adult female Wistar albino rats. Rats were divided into four groups (G); G1, control group; G2, RT-only group, G3, S-only group; G4, RT plus S group. Rats were sacrificed at 6th hour; 21st and 100th days after RT. Salivary gland samples were taken for microscopical examination.

Periductal-perivascular inflammation scores in 21st and 100th days tended to be higher in G2 than in G4, but the difference was not statistically significant. Periductal-perivascular fibrosis score was significantly different between the groups in 100th day (P: 0.010). Pairwise comparisons revealed that periductal-perivascular fibrosis scores were different between G1 and G2 (P: 0.014), G2 and G3 (P: 0.014), G2 and G4 (P: 0.034).

MR blockade with S, when initiated before RT, ameliorates late radiation-induced fibrosis in the submandibular glands.

This work investigated the transfer factor of radionuclides from clay loam soil to sesame and cowpea plants.

Twenty samples from the plant and twenty samples from its soil were collected from five different locations (farms). Gamma-ray spectrometry was used to determine the activity concentration for the samples. In addition, the soil physicochemical characteristics such as pH value, the amount of organic content and texture of soil were investigated by pH meter, Walkley-Black and particle size distribution (Pipette) methods, respectively.

The average activity concentrations, respectively, of 226Ra, 232Th, and 40K were 12.75, 10.20 and 131.75 Bq kg-1 for the clay loam soil, 5.20, 4.15 and 171.00 Bq kg-1 for sesame and 6.70, 5.60 and 182.90 Bq kg-1 for cowpea. The transfer factor from soil to sesame and cowpea was discussed. The average values of transfer factor were 0.51, 0.53 and 1.36 (for cowpea) and 0.42, 0.43 and 1.33 (for sesame), respectively for 226Ra, 232Th and 40K. The results showed that the transfer factor in cowpea is much greater than that in sesame. As a result of the ingestion of the radionuclides from the plants, the average annual dose was lower than the 290 μSv y-1 world average.

Accordingly, the radiological risk due to the intake of the natural radionuclides in these plants was immaterial.

To show whether the 2D-array scanning system can be used as a substitute for the MP3-water phantom, we have used a comparison of beam profiles and the percentage depth doses for both electron beams and the photons, also we have confirmed the validation of the results by CMS XiO treatment planning system.

Beam data was obtained for MP3-water phantom and 2D-array scanning system for 6 MV and 15 MV photon beam; and 4, 6, 8, 10, 12 and 15 MeV electron beams generated from  ONCOR Digital Medical Linear accelerator for (2×2cm2, 3×3cm2, 5×5cm2,10×10cm2,15×15cm2and 20×20cm2) at 10cm depth. CMS XiO treatment planning system was utilized for validation of the obtained data.

doses distribution for the two studied systems is compared with uncertainties within the recommended limits. It is found that there's no vital variation in flatness and symmetry obtained from the 2D-Array as compared to the quality MB3-Water Phantom Flatness and symmetry obtained is well at intervals the limit of ±3%.

it is concluded that the 2D-Array-729 is used for the routine measuring of the photon beam profiles as alternative to water phantom.

Photoneutrons are produced during the radiotherapy treatment, when high energy X rays interacts with structures of the head of the linear accelerator (linac). The present day TPS are not taking into account the photo-neutron dose and the biological effects associated with it. The late induction of cancer and recurrence of the disease in old cancer patients are being frequently reported.

Patients undergoing radiotherapy treatment with 15 MV X rays from a Siemens Primus Plus linear accelerator was considered for the study. In the present work, photoneutron spectrum from the linac head is measured using CR 39 SSNTD and the corresponding dose is calculated using Geant4. The composite photoneutron spectrum from the linac head and the corresponding dose was calculated using the kerma evaluation method in a human equivalent tissue phantom. The repeated calculation outcomes and the covariance error analysis in the nuclear data give consistency and an accuracy of 2 % in the results.

The result shows that significant amount of photoneutron dose was deposited during radiotherapy treatment when high energy X rays are used. The photoneutron production from the patient itself is yet another major issue which will cause out off field dose.

This work gives importance in considering the photoneutron dose during radiotherapy planning and protection. This extra dose might be a factor that contributes to the induction of cancer and also to the recurrence of cancer to previously cured patients.

The use of various types of radioactive drugs has increased the usefulness of nuclear medicine. The efficiency of the labeling radioactive isotope 99mTc is crucial for the accuracy and reliability of an examination. We conducted a survey on the quality control (QC) of radioactive isotopes (RI) by measuring their purity.

The QC (always or necessary) of radiopharmaceuticals was confirmed in 12 medical institutions in a metropolitan area. The radiochemical purity (RCP) of 99mTc-HDP and 99mTc-phytate was determined based on the measured radionuclide purity of 99mTc containing 99Mo. In addition, the effect of time after labeling and time after elution was analyzed.

None of the 12 hospitals regularly performed QC, and five hospitals administered QC when necessary. The average of 30 measurements of the 99Mo content in 99mTc from three manufacturers was 0.0109 for A, 0.0121 for B, and 0.0114 for C. The average labeling efficiency was 96.02% for 99mTc-HDP and 94.97% for 99mTc-phytate after labeling. The labeling efficiency of 99mTc-HDP with different times after elution was 97.56%, 95.41%, 94.86%, 93.76%, and 91.89% after 0.5, 2, 4, 6, and 8 h, respectively, and that for 99mTc-phytate was 97.21%, 97.21%, 94.42%, 93.35%, and 89.91% after 0.5, 2, 4, 6, and 8 h, respectively.

We analyzed the degree of maintenance needed for labeling efficiency. The degree of change should be provided to the clinical practitioner as basic data for the QC of the radiopharmaceutical.

The influence of the limit ring on the final dose distribution in the design of the lung cancer intensity-modulated radiation therapy (IMRT) plan was studied.

A total of 20 patients with lung cancer in 2017 were selected. Seven radiation beams were designed for each patient, and the limit ring width (RW) was set at 0.6, 0.8, 1.0, and 1.2 cm, respectively. The distance between the inner diameter of the limit ring and the target area (RD) was set 0.6, 0.8, 1.0, and 1.2 cm, respectively. The other parameters used in the plan were set at the same position. In addition, the conformity index (CI) and homogeneity index (HI) were calculated, and normal tissues were assessed.

Under the condition of the same number of radiation beams and the same distance between the limit ring and the target area, the smaller the limit ring, the better the CI of the target area and the less the HI of the target area. When the size of the limit ring was set the same, the closer the limit ring was to the target area, the better the CI of the dose in the target area, and the less the HI of the target area.

In central lung cancer, when the target volume is approximately 800 cc, the optimal dose distribution is obtained when the RW is set at 0.8 cm and the RD is set at 0.6 cm.