Biological Effects Of Ionizing Radiation Research Articles

Image quality and radiation dose from pediatric abdomen-pelvis CT scans

Introduction: The aim of this study is to assess the organ doses, effective dose, image quality, and the potential risk of developing radiation-related cancer in children undergoing computed tomography (CT) scans of the abdomen-pelvis. Methods: The research involved 219 pediatric patients (129 males and 90 females) who underwent an abdomen-pelvic CT examination. The patients were categorized into four age groups: <1, 1-4, 5-9, and 10-14 years old. The NCICT software version 3.0 was utilized to estimate the organ doses and effective dose. Estimation of cancer incidence risks were conducted according to the Biological Effects of Ionizing Radiation (BEIR) VII report. The image quality was evaluated by measuring the level of noise, as well as the signal-to-noise ratio, and contrast-to-noise ratio. Results: The colon received the highest organ dose in all age groups. The risk of all cancers was 75.38 per 100,000 for the <1 age group, and it decreased to 56.10 for the 10-14 age group. The cancer risks were statistically higher for females (p < 0.05). The mean noise values for the liver, aorta, and paraspinal muscle were found to be 9.08, 11.04, and 8.21, respectively. Conclusion: The findings of present study indicate that pediatric abdomen-pelvis CT examinations carry a potential risk of cancer that should not be disregarded. Consequently, it is crucial to prioritize radiation protection measures in children compared to adults.

Estimation of Radiation Equivalent Dose and Lifetime Attributable Risk from Pediatric CAP CT Examination

Aim: This study aims to estimate equivalent doses (EqDs) and life attributable risks (LARs) for pediatric patients who underwent chest–abdominal–pelvic (CAP) CT examinations in Madinah, Saudi Arabia. Methodology: This retrospective study collected data from 120 pediatric patients who underwent CAP CT examinations. The data were categorized by the age and gender of the pediatric patients. Then, the EqDs were computed using the NCICT (National Cancer Institute dosimetry system for computed tomography) program, and LARs were estimated from the equivalent dose (EqD) results using age- and gender-specific cancer risk models found in the Committee on the Biological Effects of Ionizing Radiation (BEIR) VII Phase 2 (2006). Results: The EqD range was 0.9 to 7.55 mSv for the prostate and colon (males and females), respectively. LARs for female breast and lung cancers were considered to have the highest values among the age groups. Nevertheless, LARs of the colon, liver, and leukemia cancers were higher for males than females. The LAR range of cancer incidence was 0.6 to 63.1 per 100,000 cases for prostate (aged 10–≤15 years) and breast (females aged 1≤–<5 years), respectively. The LAR range of cancer mortality was 0.1 to 41.9 per 100,000 cases for prostate (aged 10–≤15 years) and lung (females aged 1≤–<5 years). Conclusions: LARs of all cancer incidence and mortality from CAP CT examination were higher for pediatric females than males (with an average of 54%). This highlights the importance of considering pediatric patient gender and implementing optimization and protective measures in CAP CT examinations. LARs of breast and lung (for females) and colon (for males) cancers were found to have the highest values among the age groups. However, LARs of cancer incidence and mortality for colon, liver, and leukemia for males were higher than those for females.

Paediatric cancer risks associated with chest computed tomography (CT) scans: comparison of routine chest and COVID-19 diagnosis CT protocols

The aim of this study is to compare the radiation dose and cancer incidence risk associated with two chest Computed Tomography (CT) protocols: routine chest CT (RC-CT) and COVID-19 Diagnosis CT protocol (CD-CT). The study included 254 pediatric patients divided into three age groups: G1 (<5), G2 (5–<10), and G3 (10–15). The effective diameter, volumetric CT dose index (CTDIvol), dose length product (DLP), size specific dose estimate (SSDE), organ doses, and cancer incidence risk were calculated for the two protocols. Organ doses (mSv) and effective dose (mSv) were estimated using the National Cancer Institute dosimetry system for CT (NCICT) software. Estimation of cancer incidence risks were conducted according to the Biological Effects of Ionizing Radiation (BEIR) VII report. The oldest group (G3) in two protocols exhibited the greatest values for CTDIvol, DLP, effective dose and SSDE. The results showed that CD-CT protocol resulted in statistically significant (p < 0.05) lower organ doses and cancer incidence risk. The cancer incidence risk for both protocols did not exceed the reference levels reported in literature surveys on pediatric CT chest radiation dose for all age groups. It can be concluded that the choice of CT protocol can significantly impact the radiation dose received by pediatric patients during CT imaging, highlighting the importance of carefully selecting the appropriate protocol to minimize radiation exposure.

Estimation and comparison of the effective dose and lifetime attributable risk of thyroid cancer between males and females in routine head computed tomography scans: a multicentre study.

A significant number of head computed tomography (CT) scans are performed annually. However, due to the close proximity of the thyroid gland to the radiation field, this procedure can expose the gland to ionising radiation. Consequently, this study aimed to estimate organ dose, effective dose (ED) and lifetime attributable risk (LAR) of thyroid cancer from head CT scans in adults. Head CT scans of 74 patients (38 males and 36 females) were collected using three different CT scanners. Age, sex, and scanning parameters, including scan length, tube current-time product (mAs), pitch, CT dose index, and dose-length product (DLP) were collected. CT-Expo software was used to calculate thyroid dose and ED for each patient based on scan parameters. LARs were subsequently computed using the methodology presented in the Biologic Effects of Ionizing Radiation (BEIR) Phase VII report. Although the mean thyroid organ dose (2.66 ± 1.03 mGy) and ED (1.6 ± 0.4 mSv) were slightly higher in females, these differences were not statistically significant compared to males (mean thyroid dose, 2.52 ± 1.31 mGy; mean ED, 1.5 ± 0.4 mSv). Conversely, there was a significant difference between the mean thyroid LAR of females (0.91 ± 1.35) and males (0.20136 ± 0.29) (P = 0.001). However, the influencing parameters were virtually identical for both groups. The study's results indicate that females have a higher LAR than males, which can be attributed to higher radiation sensitivity of the thyroid in females. Thus, additional care in the choice of scan parameters and irradiated scan field for female patients is recommended.

Lifetime Attributable Breast Cancer Risk Related to Lung CT Scan in Women with Covid19

Abstract
 Purpose: Organ, effective dose, and Lifetime Attributable Risk (LAR) of breast cancer incidence related to lung Computed Tomography (CT) scans were evaluated. Seven hundred thirty-five female patients (20-50 years old) with Coronavirus (COVID-19) in four medical imaging centers in Tehran, Iran, were surveyed. Patients’ data, including age, sex, and exposure information (Kilovoltage (KVp), milliampere-second (mAs), pitch factor, Computed Tomography Dose Index (CTDIvol), and Dose Length Product (DLP)) were extracted from dose report pages in picture archiving and communication systems (PACS).
 Materials and Methods: Patients were divided into six age groups of 20-25, 25-30, 30-35, 35–40, 40-45, and 45–50 years. Breast, thyroid, lung, and heart absorbed doses, and also effective doses, were calculated by National Cancer Institute (NCICT) software, and LAR of breast cancer incidence has been evaluated by the Biological Effect of Ionizing Radiation (BEIR) VII in phase 2 report.
 Results: The average doses of breast, thyroid, lung, the heart were 3.97, 4.75, 4.10, and 3.37 mGy, respectively. Also, the average effective dose was 2.56 mSv. The average LAR of breast cancer in female patients was 7.45 per 100,000 exposures, decreasing dramatically with age. It was clear that exposure parameters and organ absorbed dose were significantly different between medical imaging centers (P value<0.05).
 Conclusion: Although the CT scan is a useful instrument in the diagnosis of Corona disease, it should be suggested with caution due to the increased risk of breast cancer, especially in younger women and pediatrics. Also, low-dose CT scan protocols are recommended to minimize radiation effective and absorbed doses.

Evaluation of patient radiation dose and risk of cancer from CT examinations.

Computed tomography (CT) examinations have been increasingly requested and become the major sources of patient exposure. The cancer risk from CT scans is contingent upon the amount of absorbed dose of organs. This study aims to determine the organ doses and risk of cancer incidence and mortality from CT examinations at high dose (cumulative effective dose, CED ≥ 100mSv) in a single day to low dose (CED < 100mSv) from common CT procedures. Data were gathered from two academic centers of patients aged 15 to 75years old performed CT examinations during the period of 5years. CED and organ dose were calculated using Monte Carlo simulation software. Lifetime attributable risk (LAR) was determined following Biological Effects of Ionizing Radiation (BEIR) VII report based on life table and baseline cancer rates of Thai population. At high dose, the highest LAR for breast cancer incidence in young female was 82 per 100,000 exposed patients with breast dose of 148mGy (CT whole abdomen). The highest LAR for liver cancer incidence in male patient was 72 per 100,000 with liver dose of 133mGy (multiple CT scans). At low dose, the highest average LAR for breast cancer incidence in young female was 23 per 100,000 while for liver cancer incidence in male patients was 22 per 100,000 (CTA whole aorta). Even though the LAR of cancer incidence and mortality was less than 100 per 100,000, they should not be neglected. The risk of cancer incidence may be increased in later life, particularly in young patients.

Secondary cancer risk assessments following the proton therapy of lung cancer as the functions of field characteristics and patient age

Introduction Radiation-induced secondary cancers relevant to proton therapy are still a main concern among cancer survivors. This study aims to determine the effects of age at exposure and treatment field size on radiation-induced secondary tumors following the proton therapy of lung cancer within out of field organs through the Monte Carlo (MC) simulation approach. Material and Methods A full MC model of ICRP-110 male phantom was simulated to calculate the absorbed dose corresponding to secondary radiations within distant organs from the tumor volume. Then, the risks of secondary malignancies were estimated by employing the recommended risk model by the Committee of Biological Effects of Ionizing Radiation (BEIR) for different treatment field sizes and various patient ages at exposure. Results The results revealed that by increasing the patient age from 25 to 45 years, lifetime attributable risk (LAR) values were decreased. Maximum and minimum mortality rates were obtained for the liver and thyroid at the fixed age of 25 years, respectively. Calculated risk values for most near organs to the tumor were higher than those for distant organs. Changing the aperture size from 5 × 5 cm2 to 8 × 10 cm2 resulted in LAR increments with maximum variations of 12.5% for the stomach and a rough variation of 1.12 times in LAR for all exposure ages. Conclusion Our work on whole-body phantom addresses the impact of age at exposure and aperture size on LAR during the proton therapy of lung cancer. To minimize secondary cancer risks relevant to proton therapy of lung cancer, extra attention should be considered.

Secondary Cancer Risk of Radiotherapy and Imaging Examination for Two Different Malignancies in One Patient

Purpose: Radiotherapy (RT), which is considered one of the critical treatments for cancer patients is also known as adjuvant therapy and palliative care, and can be attempted alone or concurrent with chemotherapy. Although RT reduces the risk of recurrence, the scattered dose may enhance the risk of secondary cancer induction; this is raising some challenges in clinical practice. To the best of our knowledge, few studies to date have assessed such effects of brain cancer adjuvant radiotherapy.&#x0D; Materials and Methods: We estimated the RT-induced risk of secondary cancer for a 45-year-old patient who had undergone radiotherapy of the head and pelvis with a 6 MV photon beam in 15 and 10 sessions, respectively. The absorbed dose by the thyroid, breast, eye lenses, region overlying ovaries, and parotids was measured using Thermoluminescent Dosimeters (TLD). Since the patient was scanned before radiotherapy, it was decided to calculate their risk as well. To evaluate the cancer risk, radiobiological models for Excess Absolute Risk (EAR), as well as Excess Relative Risk (ERR) published by the Committee on the Biological Effects of Ionizing Radiation (BEIR) in report VII, were implemented. This study thus aimed to estimate the Risk of Exposure-Induced Death (REID) and assess the radiation dose delivered to patients from Computed Tomography (CT) scans and common diagnostic nuclear medicine examinations.&#x0D; Results: The mean risk of secondary cancer for sensitive organs was calculated 3 years after radiotherapy. The highest estimated ERR was related to the region overlying right and left ovaries for pelvic radiotherapy (47.82) and (51.17), and the next highest EAR followed by right and left eye lenses for brain radiotherapy (18.09) and (15.43), respectively. In addition, other cancers arising from CT scans had the highest REID values for solid cancer (0.0015) and bone scans revealed the highest REID values for other cancers (0.00121).&#x0D; Conclusion: Calculating the corresponding risks of RT is of great significance for the patients in procedural change. Choosing proper field sizes and adapted techniques to avoid excessive doses to healthy organs can thus be a great assistance in this regard.

Assessment of effective dose and radiation-induced cancer risk in CT-KUB

Background and objectivesAmong the various imaging techniques employed for disorders related to the renal and urinary tract systems, computed tomography of kidneys, ureters, and bladder (CT-KUB) is considered the gold standard. The study evaluated effective dose and organ equivalent dose and estimated cancer risk for patients undergoing CT-KUB scans. MethodsScans of 110 patients (76 males, 31 females; mean age 45 years) were completed using a calibrated GE Light Speed 64-slice multi-slice CT (MSCT) scanner. CT exposure parameters were recorded, including tube current, pitch factor tube potential, volume CT dose index (CTDIvol) and dose-length product (DLP), and the National Cancer Institute dosimetry system for computed tomography (NCICT) was used to calculate the effective dose for each patient. Patient organ doses for colon, breast, stomach, bladder, prostate, and ovaries were calculated and converted to estimate cancer risk, based on the Biological Effects of Ionizing Radiation (BEIR) VII report. ResultsCTDIvol, DLP, and effective dose reported mean values of 9.9 mGy, 483.57 mGy cm, and 5.8 mSv, respectively. Lifetime cancer risk ranged from 0.01% to 0.08%, with a mean of 0.03% per 100,000 CT-KUB procedures. For younger individuals, the level of risk was higher for females than for males. While male patients are at higher risk than females for colon cancer, with close risk for both genders regarding stomach and bladder cancers. A statistically significant positive correlation was observed between effective dose and body mass index (p < 0.011, r > 0.4), AP diameter (p < 0.01, r > 0.4), and transfer diameter (p < 0.01, r > 0.5). ConclusionsAlthough the reported effective doses fall within the standard limits, there is significant potential to reduce the radiation dose for patients undergoing CT-KUB. Possible options include low dose protocols and ultrasonography, depending on patient characteristics and clinical condition. Appropriate education and training of radiologic technologists can help to ensure radiation dose optimization.

Assessment of Differentiated Thyroid Carcinomas in French Polynesia After Atmospheric Nuclear Tests Performed by France

Due to the amount of iodine 131 released in nuclear tests and its active uptake by the thyroid, differentiated thyroid carcinoma (DTC) is the most serious health risk for the population living near sites of nuclear tests. Whether low doses to the thyroid from nuclear fallout are associated with increased risk of thyroid cancer remains a controversial issue in medicine and public health, and a misunderstanding of this issue may be associated with overdiagnosis of DTCs. This case-control study was conducted by extending a case-control study published in 2010 that included DTCs diagnosed between 1984 and 2003 by adding DTCs diagnosed between 2004 and 2016 and improving the dose assessment methodology. Data on 41 atmospheric nuclear tests conducted by France between 1966 and 1974 in French Polynesia (FP) were assessed from original internal radiation-protection reports, which the French military declassified in 2013 and which included measurements in soil, air, water, milk, and food in all FP archipelagos. These original reports led to an upward reassessment of the nuclear fallout from the tests and a doubling of estimates of the mean thyroid radiation dose received by inhabitants from 2 mGy to nearly 5 mGy. Included patients were diagnosed from 1984 to 2016 with DTC at age 55 years or younger and were born in and resided in FP at diagnosis; 395 of 457 eligible cases were included, and up to 2 controls per case nearest by birthdate and matched on sex were identified from the FP birth registry. Data were analyzed from March 2019 through October 2021. The radiation dose to the thyroid gland was estimated using recently declassified original radiation-protection service reports, meteorological reports, self-reported lifestyle information, and group interviews of key informants and female individuals who had children at the time of these tests. The lifetime risk of DTC based on Biological Effects of Ionizing Radiation (BEIR) VII models was estimated. A total of 395 DTC cases (336 females [85.1%]; mean [SD] age at end of follow-up, 43.6 [12.9] years) and 555 controls (473 females [85.2%]; mean [SD] age at end of follow-up, 42.3 [12.5] years) were included. No association was found between thyroid radiation dose received before age 15 years and risk of DTC (excess relative risk [ERR] per milligray, 0.04; 95% CI, -0.09 to 0.17; P = .27). When excluding unifocal noninvasive microcarcinomas, the dose response was significant (ERR per milligray, 0.09; 95% CI, -0.03 to 0.02; P = .02), but several incoherencies with the results of the initial study reduce the credibility of this result. The lifetime risk for the entire FP population was 29 cases of DTC (95% CI, 8-97 cases), or 2.3% (95% CI, 0.6%-7.7%) of 1524 sporadic DTC cases in this population. This case-control study found that French nuclear tests were associated with an increase in lifetime risk of PTC in FP residents of 29 cases of PTC. This finding suggests that the number of thyroid cancer cases and the true order of magnitude of health outcomes associated with these nuclear tests were small, which may reassure populations of this Pacific territory.

Ionizing Radiation Selectively Increases CXC Ligand 10 Level via the DNA-Damage-Induced p38 MAPK-STAT1 Pathway in Murine J774A.1 Macrophages.

Ionizing radiation (IR) is an important means of tumor treatment in addition to surgery and drugs. Attempts have been made to improve the efficiency of radiotherapy by identifying the various biological effects of IR on cells. Components of the tumor microenvironment, such as macrophages, fibroblasts, and vascular endothelial cells, influence cancer treatment outcomes through communication with tumor cells. In this study, we found that IR selectively increased the production of CXC motif chemokine ligand 10 (CXCL10), which is emerging as an important biomarker for determining the prognosis of anticancer treatments, without changing the levels of CXCL9 and CXCL11 in murine J774A.1 macrophages. Pretreatment with KU55933, an ataxia telangiectasia mutated (ATM) kinase inhibitor, significantly inhibited IR-induced CXCL10 production. In contrast, pretreatment with N-acetyl-cysteine or glutathione, a reactive oxygen species scavenger, did not inhibit IR-induced CXCL10 production. Further, we attempted to identify the intracellular molecular target associated with the IR-induced increase in CXCL10 secretion by J774A.1 macrophages. IR phosphorylated p38 mitogen-activated protein kinase (MAPK) and signal transducer and activator of transcription 1 (STAT1) in J774A.1 macrophages, and p38 MAPK and STAT1 were involved in CXCL10 via IR using pharmacological inhibitors (SB203580 and fludarabine, respectively) and the siRNA technique.

The Gofman-Tamplin Cancer Risk Controversy and Its Impact on the Creation of BEIR I and the Acceptance of LNT.

The major public dispute between John Gofman and his colleague Arthur Tamplin and the United States (US) Atomic Energy Commission (AEC) at the end of the 1960s and during the early 1970s significantly impacted the course of cancer risk assessment in the US and worldwide. The challenging and provocative testimony of Gofman to the US Senate in early 1970 lead to the formation of the US National Academy of Sciences (NAS) Biological Effects of Ionizing Radiation (BEIR) I Committee in order to evaluate the accuracy of claims by Gofman and Tamplin that emissions from nuclear power plants would significantly increase the occurrence of genetic defects and cancers. BEIR I recommended the adoption of the linear non-threshold (LNT) dose response model for the assessment of cancer risks from radiation exposures. The US EPA adopted this recommendation and generalized it to incorporate chemical carcinogens, thereby affecting cancer risk assessments over the next decades. Despite the scientific limitations and ideological framework of their perspectives, Gofman and Tamplin are of considerable historical importance since they had essential roles in affecting the adoption of LNT by regulatory agencies.

Association between exposures to radon and γ-ray radiation and histologic type of lung cancer in Eldorado uranium mining and milling workers from Canada.

BackgroundThe authors assessed the association between radon decay products (RDP) exposure and histologic types of incident lung cancer in a cohort of 16,752 (91.6% male) Eldorado uranium workers who were first employed from 1932 to 1980 and were followed through 1969–1999.MethodsSubstantially revised identifying information and RDP exposures were obtained on workers from the Port Radium and Beaverlodge uranium mines and from the Port Hope radium and uranium refinery and processing facility in Canada. Poisson regression was conducted using the National Research Council's Biological Effects of Ionizing Radiation (BEIR) VI–type models to estimate the risks of lung cancer by histologic type from RDP exposures and γ‐ray doses.ResultsLung cancer incidence was significantly higher in workers compared with the general Canadian male population. Radiation risks of lung cancer for all histologic types (n = 594; 34% squamous cell, 16% small cell, 17% adenocarcinoma) increased with increasing RDP exposure, with no indication of curvature in the dose response (excess relative risk per 100 working level months = 0.61; 95% confidence interval, 0.39–0.91). Radiation risks did not differ by histologic type (p = .144). The best‐fitting BEIR VI–type model included adjustments for the significant modifying effects of time since exposure, exposure rate, and attained age. The addition of γ‐ray doses to the model with RDP exposures improved the model fit, but the risk estimates remained unchanged.ConclusionsThe first analysis of radiation risks of lung cancer histologic types in the Eldorado cohort supported the use of BEIR VI–type models to predict the future risk of histologic types of lung cancer from past and current RDP exposures.Lay summary Lung cancer survival depends strongly on the cell type of lung cancer.The best survival rates are for patients who have the adenocarcinoma type.This study included 16,752 Eldorado uranium workers who were exposed to radon and γ‐ray radiation during 1932–1980, were alive in 1969, and were followed for the development of new lung cancer during 1969–1999.One third of all lung cancers were of the squamous cell type, whereas the adenocarcinoma and small cell types accounted for less than 20% each.Radiation risks of lung cancer among men increased significantly with increasing radon exposure for all cell types, with the highest risks estimated for small cell and squamous cell lung cancers.

Impact of Different Beam Energies on The Incidence of Thyroid Cancer in Breast Cancer Radiotherapy

Purpose: During breast radiotherapy, the organs which are located out of the radiation field such as the thyroid are prone to secondary cancers. The present study aims to evaluate the risk of thyroid cancer in breast cancer radiotherapy in conventional and conformal radiation therapy.&#x0D; Materials and Methods: The data related to the thyroid dose in radiotherapy of breast cancer from the study by Behmadi et al. were used. In their study, the thyroid dose was measured on the Alderson RANDO phantom for four different breast cancer treatment plans and two photon energies. Using the Biological Effects of Ionizing Radiation (BEIR) VII model, the risk of thyroid cancer was estimated in conventional and conformal plans with two photon energies (6 and 15 MV) in breast cancer radiotherapy.&#x0D; Results: The Lifetime Attributable Risk (LAR) for thyroid cancer in the conventional technique was only 7.5% higher than that in the conformal technique. In the conventional treatment technique, LAR for thyroid cancer at 6 MV in all age groups was 17% higher than the 15 MV energy. However, the LAR for thyroid cancer in conformal technique at 15 MV energy was 50% higher than at 6 MV energy.&#x0D; Conclusion: Applying high energy for radiotherapy of breast cancer, in the conventional technique, could reduce the risk of thyroid cancer. But at high energies, the risk of thyroid cancer in the conformal technique is considerably higher than that at low energy. Therefore, it is suggested that the impact of energies be evaluated to reduce the risk of thyroid cancer in breast cancer radiotherapy.

USP9X Is Required to Maintain Cell Survival in Response to High-LET Radiation.

Ionizing radiation (IR) principally acts through induction of DNA damage that promotes cell death, although the biological effects of IR are more broad ranging. In fact, the impact of IR of higher-linear energy transfer (LET) on cell biology is generally not well understood. Critically, therefore, the cellular enzymes and mechanisms responsible for enhancing cell survival following high-LET IR are unclear. To this effect, we have recently performed siRNA screening to identify deubiquitylating enzymes that control cell survival specifically in response to high-LET α-particles and protons, in comparison to low-LET X-rays and protons. From this screening, we have now thoroughly validated that depletion of the ubiquitin-specific protease 9X (USP9X) in HeLa and oropharyngeal squamous cell carcinoma (UMSCC74A) cells using small interfering RNA (siRNA), leads to significantly decreased survival of cells after high-LET radiation. We consequently investigated the mechanism through which this occurs, and demonstrate that an absence of USP9X has no impact on DNA damage repair post-irradiation nor on apoptosis, autophagy, or senescence. We discovered that USP9X is required to stabilize key proteins (CEP55 and CEP131) involved in centrosome and cilia formation and plays an important role in controlling pericentrin-rich foci, particularly in response to high-LET protons. This was also confirmed directly by demonstrating that depletion of CEP55/CEP131 led to both enhanced radiosensitivity of cells to high-LET protons and amplification of pericentrin-rich foci. Our evidence supports the importance of USP9X in maintaining centrosome function and biogenesis and which is crucial particularly in the cellular response to high-LET radiation.

Development of clinical application program for radiotherapy induced cancer risk calculation using Monte Carlo engine in volumetric-modulated arc therapy

BackgroundThe purpose of this study is to develop a clinical application program that automatically calculates the effect for secondary cancer risk (SCR) of individual patient. The program was designed based on accurate dose calculations using patient computed tomography (CT) data and Monte Carlo engine. Automated patient-specific evaluation program was configured to calculate SCR.MethodsThe application program is designed to re-calculate the beam sequence of treatment plan using the Monte Carlo engine and patient CT data, so it is possible to accurately calculate and evaluate scatter and leakage radiation, difficult to calculate in TPS. The Monte Carlo dose calculation system was performed through stoichiometric calibration using patient CT data. The automatic SCR evaluation program in application program created with a MATLAB was set to analyze the results to calculate SCR. The SCR for organ of patient was calculated based on Biological Effects of Ionizing Radiation (BEIR) VII models. The program is designed to sequentially calculate organ equivalent dose (OED), excess absolute risk (EAR), excess relative risk (ERR), and the lifetime attributable risk (LAR) in consideration of 3D dose distribution analysis. In order to confirm the usefulness of the developed clinical application program, the result values from clinical application program were compared with the manual calculation method used in the previous study.ResultsThe OED values calculated in program were calculated to be at most approximately 13.3% higher than results in TPS. The SCR result calculated by the developed clinical application program showed a maximum difference of 1.24% compared to the result of the conventional manual calculation method. And it was confirmed that EAR, ERR and LAR values can be easily calculated by changing the biological parameters.ConclusionsWe have developed a patient-specific SCR evaluation program that can be used conveniently in the clinic. The program consists of a Monte Carlo dose calculation system for accurate calculation of scatter and leakage radiation and a patient-specific automatic SCR evaluation program using 3D dose distribution. The clinical application program that improved the disadvantages of the existing process can be used as an index for evaluating a patient treatment plan.

Role of DNA Damage and Repair in Detrimental Effects of Ionizing Radiation

Ionizing radiation (IR) is considered a traditional mutagen and genotoxic agent. Exposure to IR affects in all cases biological systems and living organisms from plants to humans mostly in a pernicious way. At low (&lt;0.1 Gy) and low-to-medium doses (0.1–1 Gy), one can find in the literature a variety of findings indicating sometimes a positive-like anti-inflammatory effect or detrimental-like toxicity. In this Special Issue and in general in the current research, we would like to acquire works and more knowledge on the role(s) of DNA damage and its repair induced by ionizing radiations as instigators of the full range of biological responses to radiation. Emphasis should be given to advances offering mechanistic insights into the ability of radiations with different qualities to severely impact cells or tissues. High-quality research or review studies on different species projected to humans are welcome. Technical advances reporting on the methodologies to accurately measure DNA or other types of biological damage must be highly considered for the near future in our research community, as well. Last but not least, clinical trials or protocols with improvements to radiation therapy and radiation protection are also included in our vision for the advancement of research regarding biological effects of IR.

Thyroid Cancer Risk in Patients Undergoing 64 Slice Brain and Paranasal Sinuses Computed Tomography

Purpose: Computed Tomography (CT) is a fundamental part of diagnosis of diseases. During CT examinations organs in and out of scanned volume are exposed to ionization radiation. The aim of this study was Estimation Thyroid cancer risk in Patients who Underwent 64 Slice brain and paranasal sinuses CT scan. Materials and Methods: with permission from the authors and editor, data related to thyroid dose of 40 patients in Mazyar et al.'s paper was used and by using Biological Effects of Ionizing Radiation (BEIR)VII model thyroid cancer risk was calculated for different ages at exposure in male and female. Results: In both brain and paranasal sinuses CT, ERR values in female patients were twice as many as those in male patients. At age range from 20 to 40 years, ERR was considerably more than at age range 40-60 years since young patients are more radiosensitive than old patients. Conclusion: The calculations of ERR indicate that PNS and brain CT increase the theoretical risk of thyroid cancer incidence. Although the ERR values are low, impacts on the thyroid cancer incidence should not be disregarded.

Assessment of Radiation-Induced Secondary Cancer Risks In Breast Cancer Patients Treated with 3D Conformal Radiotherapy

Introduction: In the current study, radiation-induced secondary cancers risks (SCRs) have been evaluated in irradiated organs following three-dimensional conformal radiation therapy (3D-CRT) of breast cancer using the BEIR (Biological Effects of Ionizing Radiation) VII models. Material and Methods: Sixty patients with left-sided breast cancer were chosen for this study and who were treated with a total breast dose of 50 Gy in 2 Gy fractions. Differential dose volume histograms (dDVHs) were retrieved and values of mean organs dose were computed. SCRs to the heart, ipsilateral lung, liver, thyroid, and contralateral were estimated using both excess relative risk (ERR) and excess absolute risks (EAR) models as proposed by BEIR VII committee of the U.S National Academy of Sciences.Average values of organ dose to these 60 patients were 6.8, 15.9, 3.7, 4.5 and 1.5 Gy in the thyroid, ipsilateral lung, contralateral breast, heart, and liver, respectively. Results: From the BEIR VII models, ERR incidence was estimated to be 21.2, 5.0, 1.6 and 1.4 Gy-1 for the ipsilateral lung, thyroid, heart, and liver, respectively. EAR for cancer incidence was calculated as 105, 45.8, 15.8 and 4.35 Gy-1 for these same organs. Conclusion: The study showed SCRs quantitatively to various organs for patients with breast cancer who received 3D-CRT. We found that 3D-CRT treatment is associated with a relatively high SCR in the lung.

Cardiac catheterization real-time dynamic radiation dose measurement to estimate lifetime attributable risk of cancer.

Cardiac catheterization procedure is the gold standard to diagnose and treat cardiovascular disease. However, radiation safety and cancer risk remain major concerns. This study aimed to real-time dynamic radiation dose measurement to estimate lifetime attributable risk (LAR) of cancer incidence and mortality in operators. Coronary angiography (CA) with percutaneous coronary intervention (PCI), CA, and others (radiofrequency ablation, pacemaker and defibrillator implantation) procedures with different beam directions, were undertaken on x-ray angiography system. A real-time electronic personal dosimeter (EPD) system was used to measure the radiation dose of staff during all procedures. We followed the Biological Effects of Ionizing Radiation (BEIR) VII report to estimate the LAR of all cancer incidence and mortality. Primary operators received radiation dose in CA with PCI, CA, and others procedures were 59.33 ± 95.03 μSv, 39.81 ± 103.85 μSv, and 21.92 ± 37.04 μSv, respectively. As to the assistant operators were 30.03 ± 55.67 μSv, 14.67 ± 14.88 μSv, and 4 μSv, respectively. LAR of all cancer incidences for staffs aged from 18 to 65 are varied from 0.40% for males to 1.50% for females. LAR of all cancer mortality for staffs aged from 18 to 65 are varied from 0.22% for males to 0.83% for females. Our study provided an easy, real-time and dynamic radiation dose measurement to estimate LAR of cancer for staff during the cardiac catheterization procedures. The LAR for all cancer incidence is about twice that for cancer mortality. Although the radiation doses of staff are lower during each procedure, the increased years of service leads to greater radiation risk to the staff.