- Patient-specific voxelized phantoms created from CT data can provide more accurate organ dose estimates than standardized reference phantoms, as they account for individual patient anatomy.
- Organ doses estimated from patient-specific dose maps generated through Monte Carlo simulations are patient-specific, while effective dose calculated using population-based weighting factors cannot be patient-specific.
- While reference phantoms allow estimation of partial organ irradiation beyond the scan range, patient-specific methods provide variability in organ doses not represented in standardized references and could improve radiation dose management.
The Advantages of Two Dimensional Techniques (2D) in Pituitary Adenoma TreatmentIOSR Journals
The purpose of the study is to evaluate the two dimensional dose distribution techniques in pituitary adenoma patient treatment in order to provide 2D dose coverage to the target volume while sparing organs at risk (OARs). The CT simulator was used to radiograph 300 patients of pituitary adenomas to conform 2D dose distribution planning inside the tumour bed , and its structures were delineated; including gross target volume (GTV), clinical target volume (CTV), and planning target volume (PTV)], as well as organs at risks (OARs) . Dose distribution analysis was edited to provide 2D dose coverage to the target while sparing organs at risk. The main results of the study were, 2D dose distribution plans increases the unnecessary dose to the critical organs according to their geographical location from the pituitary adenoma site, and the present study , concludes that when the tumour dose increases from 45 to 55 Gy there is a linear proportional increment of dose to the organs at risks, and when the dose is about 60 Gy in 2D, the increment of unnecessary dose to temporal lobe is 0.31 Gy, and to eye is0.34Gy, and to optic chiasm is 0.42 Gy respectively .New techniques, which will lessen the unnecessary dose to OARs, needed to be developed .
Vmat technique for Breast, Head and Neck, Brain and Craniospinal irradiation ...Biplab Sarkar
Past, present and future of VMAT technique in different sites: Breast, Head and Neck, Brain and Craniospinal irradiation for medduloblastoma and PNET treatment.
The Advantages of Two Dimensional Techniques (2D) in Pituitary Adenoma TreatmentIOSR Journals
The purpose of the study is to evaluate the two dimensional dose distribution techniques in pituitary adenoma patient treatment in order to provide 2D dose coverage to the target volume while sparing organs at risk (OARs). The CT simulator was used to radiograph 300 patients of pituitary adenomas to conform 2D dose distribution planning inside the tumour bed , and its structures were delineated; including gross target volume (GTV), clinical target volume (CTV), and planning target volume (PTV)], as well as organs at risks (OARs) . Dose distribution analysis was edited to provide 2D dose coverage to the target while sparing organs at risk. The main results of the study were, 2D dose distribution plans increases the unnecessary dose to the critical organs according to their geographical location from the pituitary adenoma site, and the present study , concludes that when the tumour dose increases from 45 to 55 Gy there is a linear proportional increment of dose to the organs at risks, and when the dose is about 60 Gy in 2D, the increment of unnecessary dose to temporal lobe is 0.31 Gy, and to eye is0.34Gy, and to optic chiasm is 0.42 Gy respectively .New techniques, which will lessen the unnecessary dose to OARs, needed to be developed .
Vmat technique for Breast, Head and Neck, Brain and Craniospinal irradiation ...Biplab Sarkar
Past, present and future of VMAT technique in different sites: Breast, Head and Neck, Brain and Craniospinal irradiation for medduloblastoma and PNET treatment.
The Computed Tomography (CT) dose output of some selected hospitals in the Federal capital Territory, Abuja, Nigeria have been determined by calculating the Effective doses of CT Chest and Abdomen-Pelvis of selected hospitals and compared its average with the Mean Reference Dose of CT Chest and Abdomen-Pelvis from four hospitals in the Federal Capital Territory, Abuja, Nigeria. Effective Dose and Scan type were extracted from the CT Chest and Abdomen-Pelvis examinations recorded. The Effective Dose of each patient undergoing the Chest and Abdomen-Pelvis examinations were calculated using the coefficient factor and the DLP values. Patients’ CT dose data from the ages of 18 to 60years from each of the 4 centres for each study type from January, 2013 to December, 2014 was extracted. A total of 112 patients’ CT dose data was extracted. Chest CT Effective Dose ranged from 9.0 to 34.0mSv, while Abdomen-Pelvis CT Effective Dose ranged from 15.9 to 61.0 for all the Centres in Federal Capital Territory, Abuja. This is higher than the recommended Reference Effective Dose range for CT Chest which is from 5 – 7mSv. and for CT Abdomen-Pelvis is from 8 – 14mSv. The mean effective dose from the Chest CT is 21.8mSv and from the Abdomen-Pelvis is 31.9mSv.
My co-authors and I have created an R package that allows the user to perform a fully quantitative analysis of DCE-MRI (dynamic contrast-enhanced magnetic resonance imaging) data. With applications in oncology in mind, users can interrogate the perfusion characteristics of tissue in order to compare between treatment groups and pre-/post-treatment.
Intensity Modulated Radiation Therapy (IMRT) is an advanced mode of high-precision radiotherapy that uses computer-controlled linear accelerators to deliver precise radiation doses to a malignant tumor or specific areas within the tumor by reducing radiation dose to the nearby normal tissues.
ENHANCING SEGMENTATION APPROACHES FROM GAUSSIAN MIXTURE MODEL AND EXPECTED MA...Christo Ananth
Automatic liver tumor segmentation would bigly influence liver treatment organizing strategy and follow-up assessment, as a result of organization and joining of full picture information. Right now, develop a totally programmed technique for liver tumor division in CT picture. Introductory liver division comprises of applying a functioning form strategy. In the wake of separating liver applying Super pixel division Algorithm for portioning liver tumor proficiently. In the proposed work, we will investigate these procedures so as to improve division of various segments of the CT pictures. The exploratory outcomes indicated that the proposed strategy was exact for liver tumor division.
Image registration and data fusion techniques.pptx latest saveM'dee Phechudi
Medical imaging is the fundamental tool in conformal radiation therapy. Almost every aspect of patient management involves some form of two or three dimensional image data acquired using one or more modality.
Image data are now used for diagnosis and staging, for treatment planning and delivery and for monitoring patients after therapy.
The Computed Tomography (CT) dose output of some selected hospitals in the Federal capital Territory, Abuja, Nigeria have been determined by calculating the Effective doses of CT Chest and Abdomen-Pelvis of selected hospitals and compared its average with the Mean Reference Dose of CT Chest and Abdomen-Pelvis from four hospitals in the Federal Capital Territory, Abuja, Nigeria. Effective Dose and Scan type were extracted from the CT Chest and Abdomen-Pelvis examinations recorded. The Effective Dose of each patient undergoing the Chest and Abdomen-Pelvis examinations were calculated using the coefficient factor and the DLP values. Patients’ CT dose data from the ages of 18 to 60years from each of the 4 centres for each study type from January, 2013 to December, 2014 was extracted. A total of 112 patients’ CT dose data was extracted. Chest CT Effective Dose ranged from 9.0 to 34.0mSv, while Abdomen-Pelvis CT Effective Dose ranged from 15.9 to 61.0 for all the Centres in Federal Capital Territory, Abuja. This is higher than the recommended Reference Effective Dose range for CT Chest which is from 5 – 7mSv. and for CT Abdomen-Pelvis is from 8 – 14mSv. The mean effective dose from the Chest CT is 21.8mSv and from the Abdomen-Pelvis is 31.9mSv.
My co-authors and I have created an R package that allows the user to perform a fully quantitative analysis of DCE-MRI (dynamic contrast-enhanced magnetic resonance imaging) data. With applications in oncology in mind, users can interrogate the perfusion characteristics of tissue in order to compare between treatment groups and pre-/post-treatment.
Intensity Modulated Radiation Therapy (IMRT) is an advanced mode of high-precision radiotherapy that uses computer-controlled linear accelerators to deliver precise radiation doses to a malignant tumor or specific areas within the tumor by reducing radiation dose to the nearby normal tissues.
ENHANCING SEGMENTATION APPROACHES FROM GAUSSIAN MIXTURE MODEL AND EXPECTED MA...Christo Ananth
Automatic liver tumor segmentation would bigly influence liver treatment organizing strategy and follow-up assessment, as a result of organization and joining of full picture information. Right now, develop a totally programmed technique for liver tumor division in CT picture. Introductory liver division comprises of applying a functioning form strategy. In the wake of separating liver applying Super pixel division Algorithm for portioning liver tumor proficiently. In the proposed work, we will investigate these procedures so as to improve division of various segments of the CT pictures. The exploratory outcomes indicated that the proposed strategy was exact for liver tumor division.
Image registration and data fusion techniques.pptx latest saveM'dee Phechudi
Medical imaging is the fundamental tool in conformal radiation therapy. Almost every aspect of patient management involves some form of two or three dimensional image data acquired using one or more modality.
Image data are now used for diagnosis and staging, for treatment planning and delivery and for monitoring patients after therapy.
Computed tomography (CT scan) is a medical imaging procedure that uses computer-processed X-rays to produce tomographic images or 'slices' of specific areas of the body. These cross-sectional images are used for diagnostic and therapeutic purposes in various medical disciplines.
Dosimetric Consequences of Intrafraction Variation of Tumor Motion in Lung St...semualkaira
The purpose of this study was to investigate the target dose discrepancy caused by intrafraction variation during Stereotactic Body Radiotherapy (SBRT) for lung cancer. Intensity-Modulated Radiation Therapy (IMRT) plans were designed based on Average Computed Tomography (AVG CT) utilizing the Planning Target Volume (PTV) surrounding the 65% and 85% prescription isodoses in both phantom and patient cases
Dosimetric Consequences of Intrafraction Variation of Tumor Motion in Lung St...semualkaira
The purpose of this study was to investigate the target dose discrepancy caused by intrafraction variation during Stereotactic Body Radiotherapy (SBRT) for lung cancer. Intensity-Modulated Radiation Therapy (IMRT) plans were designed based on Average Computed Tomography (AVG CT) utilizing the Planning Target Volume (PTV) surrounding the 65% and 85% prescription isodoses in both phantom and patient cases. Intrafraction variation was simulated by shifting the nominal plan isocenter along six directions from 0.5 mm to 4.5 mm with a 1-mm step size to produce a series of perturbed plans. The dose discrepancy between the initial plan and the perturbed plans was calculated as the percentage of the initial plan
Dosimetric Consequences of Intrafraction Variation of Tumor Motion in Lung St...semualkaira
The purpose of this study was to investigate the target dose discrepancy caused by intrafraction variation during Stereotactic Body Radiotherapy (SBRT) for lung cancer. Intensity-Modulated Radiation Therapy (IMRT) plans were designed based on Average Computed Tomography (AVG CT) utilizing the Planning Target Volume (PTV) surrounding the 65% and 85% prescription isodoses in both phantom and patient cases. Intrafraction variation was simulated by shifting the nominal plan isocenter along six directions from 0.5 mm to 4.5 mm with a 1-mm step size to produce a series of perturbed plans. The dose discrepancy between the initial plan and the perturbed plans was calculated as the percentage of the initial plan. Dose indices, including D99 and D95 for Internal Target Volume (ITV) and Gross Tumor Volume (GTV), were adopted as endpoint samples. The mean dose discrepancy was calculated under the 3-dimensional space distribution. In this study, we found that intrafraction motion can lead to serious dose degradation of the target and ITV in lung SBRT, especially during SBRT with PTV surrounding the lower isodose line. This phenomenon was compromised when 3-dimensional space distribution was considered. This result may provide a prospective reference for target dose degradation due to intrafraction motion during lung SBRT treatment.
CT is one of the highest contributor for medical radiation exposure to patients. Some common CT dose descriptors and dose optimizations methods are briefly described in this presentation.
MEDICAL IMAGING MUTIFRACTAL ANALYSIS IN PREDICTION OF EFFICIENCY OF CANCER TH...cscpconf
Based on pressing need for predictive performance improvement, we explored the value of pretherapy
tumour histology image analysis to predict chemotherapy response. It was shown that
multifractal analysis of breast tumour tissue prior to chemotherapy indeed has the capacity to
distinguish between histological images of the different chemotherapy responder groups with
accuracies of 91.4% for pPR, 82.9% for pCR and 82.1% for PD/SD.
MEDICAL IMAGING MUTIFRACTAL ANALYSIS IN PREDICTION OF EFFICIENCY OF CANCER TH...csandit
Based on pressing need for predictive performance improvement, we explored the value of pretherapy
tumour histology image analysis to predict chemotherapy response. It was shown that
multifractal analysis of breast tumour tissue prior to chemotherapy indeed has the capacity to
distinguish between histological images of the different chemotherapy responder groups with
accuracies of 91.4% for pPR, 82.9% for pCR and 82.1% for PD/SD.
Comparative dosimetry of forward and inverse treatment planning for Intensity...iosrjce
IOSR Journal of Applied Physics (IOSR-JAP) is a double blind peer reviewed International Journal that provides rapid publication (within a month) of articles in all areas of physics and its applications. The journal welcomes publications of high quality papers on theoretical developments and practical applications in applied physics. Original research papers, state-of-the-art reviews, and high quality technical notes are invited for publications.
Thesis / Doctoral Project / Dissertation Proposal
Student Information:
Student GUID Number:
833168318
Student Name: (As it appears on your transcript)
Abdullatif Abdullah
Address:
1850 Columbia Pike Apt 406, Arlington, Virginia, 22204
E-Mail Address:
[email protected]
Phone Number:
571-340-6065
Degree:
Masters in Health Physics
Expected Graduation Month/Year
05 / 2022
Dept./Major:
Health Physics
I. Title:
Estimation of Peak Skin Dose and Its Relation to the Size Specific Dose Estimate
II. Problem or Hypothesis:
The CT Dose Index (CTDIvol) was originally designed as an index of dose associated with various CT diagnostic procedures not as a direct dosimetry method for individual patient dose assessments. There is no current method for calculating peak skin dose (PSD) using the key metrics provided from the radiation dose structure report of a CT scanner. Every CT study is required to output the kVp and mAs that were used, the dose length product and CT dose index volume which will all be shown on the CT console, but there is no direct method to go straight to the PSD. This project will test the hypothesis that the SSDE has a sufficiently strong linear relationship with PSD to allow direct calculation of the PSD directly from the SSDE.
III. Review of Related Literature:
The highest radiation dose accruing at a single site on a patient’s skin is referred to as the peak skin dose (PSD) which is related to the Computed Tomography dose index (CTDIvol) that is displayed on the console of CT scanners. However, the CT Dose Index was originally designed as an index not as a direct dosimetry method for patient dose assessment. More recently, modifications to original CTDI concept have attempted to convert it into to patient dosimetry method, but have with mixed results in terms of accuracy. Nonetheless, CTDI-based dosimetry is the current worldwide standard for estimation of patient dose in CT. Therefore, CTDIvol is often used to enable medical physicists to compare the dose output between different CT scanners.
Fearon, Thomas (2011) explained that current estimation of radiation dose from CT scans on patients has relied on the measurement of Computed Tomography Dose Index (CTDI) in standard cylindrical phantoms, and calculations based on mathematical representations of “standard man.” The purpose of this study was to investigate the feasibility of adapting a radiation treatment planning system (RTPS) to provide patient-specific CT dosimetry. A radiation treatment planning system was modified to calculate patient-specific CT dose distributions, which can be represented by dose at specific points within an organ of interest, as well as organ dose-volume (after image segmentation) for a GE Light Speed Ultra Plus CT scanner. Digital representations of the phantoms (virtual phantom) were acquired with the GE CT scanner in axial mode. Thermoluminescent dosimeter (TLDs) measurements in pediatric anthropomorphic phantoms were utilized t ...
Reduced Radiation Exposure in Dual-Energy Computed Tomography of the Chest: ...MehranMouzam
ABSTRACT:
Objective: This study purports to answer the question: Does a dual-energy CT scan of the chest using reduced radiation result in images of equal or better quality compared to those produced by the gold standard of care?
Methods: With the agreement of the Ethical Review Committee and written informed consent from 32 patients, who received dual-energy CT (DECT) scan of the chest in a dual-source scanner, a second set of images was taken at a reduced radiation dose. On virtual monochromatic images at 40 and 60 keV, three thoracic radiologists evaluated image quality, normal thoracic structures, and pulmonary and mediastinal aberrations. Students analyzed the data using analysis of variance, Kappa statistics, and Wilcoxon signed-rank tests.
Results: No irregularities in the scans were missed in the virtual monochrome photographs of all patients at a lower radiation dose, and the images were found to be of sufficient quality. At 40 and 60 keV, standard-of-care pictures produced equal contrast enhancement and lesion detection. Observers were entirely consistent with one another. Among other characteristics, reduced-dose DECT had a CTDIvol of 3.0 ±0.6 mGy, and a size specified dose estimate (SSDE) of 4.0 ±0.6 mGy, a dose-length product (DLP) of 107 ±30 mgy.cm, and an effective dose (ED) of 1.15 ±0.4 mSv.
Conclusion: Dual-energy computed tomography of the chest allows for the administration of lower radiation doses (CTDIvol <3 mGy).
CT Dose Issues.pptx on the factors to be considered on radiation protectionsanyengere
summary, mobile radiography allows for the diagnostic imaging of patients who are unable to be seen in the X-ray examination room. Therefore, mobile X-ray equipment is useful for patients who have difficulty with movement. However, staff are exposed to scattered radiation from the patient, and can receive potentially harmful radiation doses during radiography. The protection of staff is of utmost importance; therefore, we investigated the occupational radiation doses received by RTs, particularly eye doses, using phantom measurements. RTs can be located close to a patient (i.e., the source of scattered radiation) during mobile radiography. As eye doses can be significant, protective measures are essential for RTs. Protective aprons are important for protecting RTs, as is increasing the distance from the radiation source (i.e., the patient). Lead glasses may also be necessary for protecting the eyes of RTs. To reduce RT radiation exposure, RTs should remain distant from the patient if possible. However, because this distance may hinder verification of the patient’s condition, RTs sometimes work in close proximity to patients. This is a patient phantom study. In future, the data may need validation by comparison with personal RT dosimeter records. It is important to evaluate the radiation doses delivered to RTs during mobile radiography, as well as the scattered radiation distribution, to ensure adequate protection. Further comparison studies may be needed using the Monte Carlo method.
radiographers and nurses have a responsibility to ensure that no one is within the radiation field during the X-ray exposure of the patient. This is achieved by informing all persons in the immediate area that an X-ray exposure is about to be made and asking them to stand a safe distance from the radiation field area.
Shielding
Placing a barrier of lead or concrete between the radiation source and an individual provides protection from X-radiation (Jones and Taylor, 2006; Ehrlich and Coakes, 2017). During mobile radiography, anyone assisting in an examination and staying in the radiation field should wear a lead-rubber apron or stand behind a mobile lead screen. Generally, walls in special care units where ionising radiation is used are designed to contain the radiation produced by the mobile X-ray tube within a set of criteria and limits determined by relevant legislation (Hart et al, 2002).
Radiation protection during mobile radiography
Nurses' understanding and adherence to radiation protection control measures during mobile radiography is of paramount importance in protecting patients, themselves and members of the public visiting the ward/unit. However, some research studies have found limited awareness and non-adherence to radiation protection control measures among nurses during mobile radiography (Anim-Sampong et al, 2015; Luntsi et al, 2016; Azimi et al, 2018). This can be attributed to a lack of radiation protection awareness programmes for nurses working
Clinical Trial Simulation to Evaluate the Pharmacokinetics of an Abuse-Deterr...Loan Pham
A CTS was performed to estimate the sample size and optimal plasma sampling times that sufficiently characterize the PK parameters (CL, Vd) from a single dose of an abuse-deterrent (AD) opioid in pediatric subjects.
Similar to Rsna2012 pediatric dosemapvstdphantom (20)
240529_Teleprotection Global Market Report 2024.pdfMadhura TBRC
The teleprotection market size has grown
exponentially in recent years. It will grow from
$21.92 billion in 2023 to $28.11 billion in 2024 at a
compound annual growth rate (CAGR) of 28.2%. The
teleprotection market size is expected to see
exponential growth in the next few years. It will grow
to $70.77 billion in 2028 at a compound annual
growth rate (CAGR) of 26.0%.
From the Editor's Desk: 115th Father's day Celebration - When we see Father's day in Hindu context, Nanda Baba is the most vivid figure which comes to the mind. Nanda Baba who was the foster father of Lord Krishna is known to provide love, care and affection to Lord Krishna and Balarama along with his wife Yashoda; Letter’s to the Editor: Mother's Day - Mother is a precious life for their children. Mother is life breath for her children. Mother's lap is the world happiness whose debt can never be paid.
As a movie director, I am often asked about the process of creating an indie film. It's a journey of passion, perseverance, and planning, and today, I'm going to take you through it.
Young Tom Selleck: A Journey Through His Early Years and Rise to Stardomgreendigital
Introduction
When one thinks of Hollywood legends, Tom Selleck is a name that comes to mind. Known for his charming smile, rugged good looks. and the iconic mustache that has become synonymous with his persona. Tom Selleck has had a prolific career spanning decades. But, the journey of young Tom Selleck, from his early years to becoming a household name. is a story filled with determination, talent, and a touch of luck. This article delves into young Tom Selleck's life, background, early struggles. and pivotal moments that led to his rise in Hollywood.
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Early Life and Background
Family Roots and Childhood
Thomas William Selleck was born in Detroit, Michigan, on January 29, 1945. He was the second of four children in a close-knit family. His father, Robert Dean Selleck, was a real estate investor and executive. while his mother, Martha Selleck, was a homemaker. The Selleck family relocated to Sherman Oaks, California. when Tom was a child, setting the stage for his future in the entertainment industry.
Education and Early Interests
Growing up, young Tom Selleck was an active and athletic child. He attended Grant High School in Van Nuys, California. where he excelled in sports, particularly basketball. His tall and athletic build made him a standout player, and he earned a basketball scholarship to the University of Southern California (U.S.C.). While at U.S.C., Selleck studied business administration. but his interests shifted toward acting.
Discovery of Acting Passion
Tom Selleck's journey into acting was serendipitous. During his time at U.S.C., a drama coach encouraged him to try acting. This nudge led him to join the Hills Playhouse, where he began honing his craft. Transitioning from an aspiring athlete to an actor took time. but young Tom Selleck became drawn to the performance world.
Early Career Struggles
Breaking Into the Industry
The path to stardom was a challenging one for young Tom Selleck. Like many aspiring actors, he faced many rejections and struggled to find steady work. A series of minor roles and guest appearances on television shows marked his early career. In 1965, he debuted on the syndicated show "The Dating Game." which gave him some exposure but did not lead to immediate success.
The Commercial Breakthrough
During the late 1960s and early 1970s, Selleck began appearing in television commercials. His rugged good looks and charismatic presence made him a popular brand choice. He starred in advertisements for Pepsi-Cola, Revlon, and Close-Up toothpaste. These commercials provided financial stability and helped him gain visibility in the industry.
Struggling Actor in Hollywood
Despite his success in commercials. breaking into large acting roles remained a challenge for young Tom Selleck. He auditioned and took on small parts in T.V. shows and movies. Some of his early television appearances included roles in popular series like Lancer, The F.B.I., and Bracken's World. But, it would take a
Maximizing Your Streaming Experience with XCIPTV- Tips for 2024.pdfXtreame HDTV
In today’s digital age, streaming services have become an integral part of our entertainment lives. Among the myriad of options available, XCIPTV stands out as a premier choice for those seeking seamless, high-quality streaming. This comprehensive guide will delve into the features, benefits, and user experience of XCIPTV, illustrating why it is a top contender in the IPTV industry.
As a film director, I have always been awestruck by the magic of animation. Animation, a medium once considered solely for the amusement of children, has undergone a significant transformation over the years. Its evolution from a rudimentary form of entertainment to a sophisticated form of storytelling has stirred my creativity and expanded my vision, offering limitless possibilities in the realm of cinematic storytelling.
Experience the thrill of Progressive Puzzle Adventures, like Scavenger Hunt Games and Escape Room Activities combined Solve Treasure Hunt Puzzles online.
Meet Dinah Mattingly – Larry Bird’s Partner in Life and Loveget joys
Get an intimate look at Dinah Mattingly’s life alongside NBA icon Larry Bird. From their humble beginnings to their life today, discover the love and partnership that have defined their relationship.
Skeem Saam in June 2024 available on ForumIsaac More
Monday, June 3, 2024 - Episode 241: Sergeant Rathebe nabs a top scammer in Turfloop. Meikie is furious at her uncle's reaction to the truth about Ntswaki.
Tuesday, June 4, 2024 - Episode 242: Babeile uncovers the truth behind Rathebe’s latest actions. Leeto's announcement shocks his employees, and Ntswaki’s ordeal haunts her family.
Wednesday, June 5, 2024 - Episode 243: Rathebe blocks Babeile from investigating further. Melita warns Eunice to stay clear of Mr. Kgomo.
Thursday, June 6, 2024 - Episode 244: Tbose surrenders to the police while an intruder meddles in his affairs. Rathebe's secret mission faces a setback.
Friday, June 7, 2024 - Episode 245: Rathebe’s antics reach Kganyago. Tbose dodges a bullet, but a nightmare looms. Mr. Kgomo accuses Melita of witchcraft.
Monday, June 10, 2024 - Episode 246: Ntswaki struggles on her first day back at school. Babeile is stunned by Rathebe’s romance with Bullet Mabuza.
Tuesday, June 11, 2024 - Episode 247: An unexpected turn halts Rathebe’s investigation. The press discovers Mr. Kgomo’s affair with a young employee.
Wednesday, June 12, 2024 - Episode 248: Rathebe chases a criminal, resorting to gunfire. Turf High is rife with tension and transfer threats.
Thursday, June 13, 2024 - Episode 249: Rathebe traps Kganyago. John warns Toby to stop harassing Ntswaki.
Friday, June 14, 2024 - Episode 250: Babeile is cleared to investigate Rathebe. Melita gains Mr. Kgomo’s trust, and Jacobeth devises a financial solution.
Monday, June 17, 2024 - Episode 251: Rathebe feels the pressure as Babeile closes in. Mr. Kgomo and Eunice clash. Jacobeth risks her safety in pursuit of Kganyago.
Tuesday, June 18, 2024 - Episode 252: Bullet Mabuza retaliates against Jacobeth. Pitsi inadvertently reveals his parents’ plans. Nkosi is shocked by Khwezi’s decision on LJ’s future.
Wednesday, June 19, 2024 - Episode 253: Jacobeth is ensnared in deceit. Evelyn is stressed over Toby’s case, and Letetswe reveals shocking academic results.
Thursday, June 20, 2024 - Episode 254: Elizabeth learns Jacobeth is in Mpumalanga. Kganyago's past is exposed, and Lehasa discovers his son is in KZN.
Friday, June 21, 2024 - Episode 255: Elizabeth confirms Jacobeth’s dubious activities in Mpumalanga. Rathebe lies about her relationship with Bullet, and Jacobeth faces theft accusations.
Monday, June 24, 2024 - Episode 256: Rathebe spies on Kganyago. Lehasa plans to retrieve his son from KZN, fearing what awaits.
Tuesday, June 25, 2024 - Episode 257: MaNtuli fears for Kwaito’s safety in Mpumalanga. Mr. Kgomo and Melita reconcile.
Wednesday, June 26, 2024 - Episode 258: Kganyago makes a bold escape. Elizabeth receives a shocking message from Kwaito. Mrs. Khoza defends her husband against scam accusations.
Thursday, June 27, 2024 - Episode 259: Babeile's skillful arrest changes the game. Tbose and Kwaito face a hostage crisis.
Friday, June 28, 2024 - Episode 260: Two women face the reality of being scammed. Turf is rocked by breaking
Matt Rife Cancels Shows Due to Health Concerns, Reschedules Tour Dates.pdfAzura Everhart
Matt Rife's comedy tour took an unexpected turn. He had to cancel his Bloomington show due to a last-minute medical emergency. Fans in Chicago will also have to wait a bit longer for their laughs, as his shows there are postponed. Rife apologized and assured fans he'd be back on stage soon.
https://www.theurbancrews.com/celeb/matt-rife-cancels-bloomington-show/
Modern Radio Frequency Access Control Systems: The Key to Efficiency and SafetyAITIX LLC
Today's fast-paced environment worries companies of all sizes about efficiency and security. Businesses are constantly looking for new and better solutions to solve their problems, whether it's data security or facility access. RFID for access control technologies have revolutionized this.
Meet Crazyjamjam - A TikTok Sensation | Blog EternalBlog Eternal
Crazyjamjam, the TikTok star everyone's talking about! Uncover her secrets to success, viral trends, and more in this exclusive feature on Blog Eternal.
Source: https://blogeternal.com/celebrity/crazyjamjam-leaks/
Tom Selleck Net Worth: A Comprehensive Analysisgreendigital
Over several decades, Tom Selleck, a name synonymous with charisma. From his iconic role as Thomas Magnum in the television series "Magnum, P.I." to his enduring presence in "Blue Bloods," Selleck has captivated audiences with his versatility and charm. As a result, "Tom Selleck net worth" has become a topic of great interest among fans. and financial enthusiasts alike. This article delves deep into Tom Selleck's wealth, exploring his career, assets, endorsements. and business ventures that contribute to his impressive economic standing.
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Early Life and Career Beginnings
The Foundation of Tom Selleck's Wealth
Born on January 29, 1945, in Detroit, Michigan, Tom Selleck grew up in Sherman Oaks, California. His journey towards building a large net worth began with humble origins. , Selleck pursued a business administration degree at the University of Southern California (USC) on a basketball scholarship. But, his interest shifted towards acting. leading him to study at the Hills Playhouse under Milton Katselas.
Minor roles in television and films marked Selleck's early career. He appeared in commercials and took on small parts in T.V. series such as "The Dating Game" and "Lancer." These initial steps, although modest. laid the groundwork for his future success and the growth of Tom Selleck net worth. Breakthrough with "Magnum, P.I."
The Role that Defined Tom Selleck's Career
Tom Selleck's breakthrough came with the role of Thomas Magnum in the CBS television series "Magnum, P.I." (1980-1988). This role made him a household name and boosted his net worth. The series' popularity resulted in Selleck earning large salaries. leading to financial stability and increased recognition in Hollywood.
"Magnum P.I." garnered high ratings and critical acclaim during its run. Selleck's portrayal of the charming and resourceful private investigator resonated with audiences. making him one of the most beloved television actors of the 1980s. The success of "Magnum P.I." played a pivotal role in shaping Tom Selleck net worth, establishing him as a major star.
Film Career and Diversification
Expanding Tom Selleck's Financial Portfolio
While "Magnum, P.I." was a cornerstone of Selleck's career, he did not limit himself to television. He ventured into films, further enhancing Tom Selleck net worth. His filmography includes notable movies such as "Three Men and a Baby" (1987). which became the highest-grossing film of the year, and its sequel, "Three Men and a Little Lady" (1990). These box office successes contributed to his wealth.
Selleck's versatility allowed him to transition between genres. from comedies like "Mr. Baseball" (1992) to westerns such as "Quigley Down Under" (1990). This diversification showcased his acting range. and provided many income streams, reinforcing Tom Selleck net worth.
Television Resurgence with "Blue Bloods"
Sustaining Wealth through Consistent Success
In 2010, Tom Selleck began starring as Frank Reagan i
Scandal! Teasers June 2024 on etv Forum.co.zaIsaac More
Monday, 3 June 2024
Episode 47
A friend is compelled to expose a manipulative scheme to prevent another from making a grave mistake. In a frantic bid to save Jojo, Phakamile agrees to a meeting that unbeknownst to her, will seal her fate.
Tuesday, 4 June 2024
Episode 48
A mother, with her son's best interests at heart, finds him unready to heed her advice. Motshabi finds herself in an unmanageable situation, sinking fast like in quicksand.
Wednesday, 5 June 2024
Episode 49
A woman fabricates a diabolical lie to cover up an indiscretion. Overwhelmed by guilt, she makes a spontaneous confession that could be devastating to another heart.
Thursday, 6 June 2024
Episode 50
Linda unwittingly discloses damning information. Nhlamulo and Vuvu try to guide their friend towards the right decision.
Friday, 7 June 2024
Episode 51
Jojo's life continues to spiral out of control. Dintle weaves a web of lies to conceal that she is not as successful as everyone believes.
Monday, 10 June 2024
Episode 52
A heated confrontation between lovers leads to a devastating admission of guilt. Dintle's desperation takes a new turn, leaving her with dwindling options.
Tuesday, 11 June 2024
Episode 53
Unable to resort to violence, Taps issues a verbal threat, leaving Mdala unsettled. A sister must explain her life choices to regain her brother's trust.
Wednesday, 12 June 2024
Episode 54
Winnie makes a very troubling discovery. Taps follows through on his threat, leaving a woman reeling. Layla, oblivious to the truth, offers an incentive.
Thursday, 13 June 2024
Episode 55
A nosy relative arrives just in time to thwart a man's fatal decision. Dintle manipulates Khanyi to tug at Mo's heartstrings and get what she wants.
Friday, 14 June 2024
Episode 56
Tlhogi is shocked by Mdala's reaction following the revelation of their indiscretion. Jojo is in disbelief when the punishment for his crime is revealed.
Monday, 17 June 2024
Episode 57
A woman reprimands another to stay in her lane, leading to a damning revelation. A man decides to leave his broken life behind.
Tuesday, 18 June 2024
Episode 58
Nhlamulo learns that due to his actions, his worst fears have come true. Caiphus' extravagant promises to suppliers get him into trouble with Ndu.
Wednesday, 19 June 2024
Episode 59
A woman manages to kill two birds with one stone. Business doom looms over Chillax. A sobering incident makes a woman realize how far she's fallen.
Thursday, 20 June 2024
Episode 60
Taps' offer to help Nhlamulo comes with hidden motives. Caiphus' new ideas for Chillax have MaHilda excited. A blast from the past recognizes Dintle, not for her newfound fame.
Friday, 21 June 2024
Episode 61
Taps is hungry for revenge and finds a rope to hang Mdala with. Chillax's new job opportunity elicits mixed reactions from the public. Roommates' initial meeting starts off on the wrong foot.
Monday, 24 June 2024
Episode 62
Taps seizes new information and recruits someone on the inside. Mary's new job
In the vast landscape of cinema, stories have been told, retold, and reimagined in countless ways. At the heart of this narrative evolution lies the concept of a "remake". A successful remake allows us to revisit cherished tales through a fresh lens, often reflecting a different era's perspective or harnessing the power of advanced technology. Yet, the question remains, what makes a remake successful? Today, we will delve deeper into this subject, identifying the key ingredients that contribute to the success of a remake.
Reimagining Classics - What Makes a Remake a Success
Rsna2012 pediatric dosemapvstdphantom
1. DME Bardo, MD1, KA Feinstein, MD2, D Pettersson, MD1, J Wiegert, PhD3, JH Yanof, PhD4
Philips Research3, Philips Healthcare4
Comparison of Patient-Specific &
Reference-Phantom Methods for
CT Dose Estimation in the
Pediatric Population
1 2
2. Purpose
Compare the characteristics of
a) age-based reference phantoms used with Monte Carlo simulation to estimate organ doses with
b) patient-specific phantoms based on CT data sets.
Compare the use of reference-phantom and patient-specific dose
distribution maps to estimate organ doses.
Describe how differences in organ dose distribution affect the estimation
of effective dose.
3. Content Organization
Reference phantom &
Patient specific phantoms
Methods for estimating
organ dose
Effective dose
calculations
Standard
From
geometrically
defined organs
in stylized
phantoms
Patient
Specific
Using
segmentation
of organs in
patient-specific
dose maps
Standard
CTDI and
stylized
phantoms
Patient
Specific
Voxelized
models based
on patient data
sets
Standard
Regression
with
DLP & E
(k factors)
Patient
Specific
Weighted
sum of dose
map organ
doses
4. Morphology of
standard reference
phantoms used for CT
dose estimation
can differ greatly from
the anatomy of an
individual patient
A standard reference
(stylized, mathematical)
phantom (ORNL,
Cristy) is compared
with CT images of a 5-6
month old patient.
Striking anatomical
differences between
reference and the
patient can effect the
estimation of dose by
dosimetry simulation
(Monte Carlo).
5. Limitations of standard dose estimates
k factor – AAPM 95.6 Table 3
Volume CTDI & DLP
are based on PMMA
cylindrical phantoms
and are not intended to
be estimates of patient
dose. They do not
account for individual
patients body
habitus, attenuation
characteristics,
or specific
scanner
dosimetry.
PMMA CTDIvol phantoms
DLP conversion factors for
Effective dose (reviewed
later) – are based stylized
phantoms with fixed
geometry (modified ORNL
set for newborn, 1, 5, and 10
YO as shown). [1,2,3]
6. The x-ray beam has more attenuation as it traverses a larger patient (yellow to red to blue) in
comparison with a smaller patient (yellow to red). Thus, the average beam intensity and dose, as the
tube rotates, tends to increase with decreasing size for the same scan parameters
Dose
(mGy)
10
20
30
40
10 mGy
CtrLG
20 mGy,
PrphryLG
40 mGy
CtrSM
40 mGy
Prphry,SM
Background
Major factors that affect CT dose include size/diameter &
tissue/material
absorption
7. Background
Average patient dose tends to increasewith decreasingpatient
size/diameter
The Size Specific Dose estimates (SSDE) [6] also show that absorbed dose increases with decreasing size. A
regression model (above) relates dose to effective diameter. The model data was based on a range of dosimetry
methods (measured and simulated), four sets of phantoms, and four scanner vendors. All phantom sets included
pediatric sizes.
“Child”
Infant Child
Anthropomorphic CTDI
Voxelized (GSF) Cylinders
Adult
8. In contrast to a standard reference phantoms (left), a patient’s CT data set can be used to
create a patient-specific (virtual) phantom (middle). In addition to patient-specific
dosimetry, this enables and individualized dose maps (right).
Standard reference vs. Patient-specific
Phantoms and Dosimetry
Voxelized
Phantom
Patient
Data setStandard
reference phantom
Patient specific
dose map
9. Dose maps can also be displayed in units of CTDI normalized absorbed dose. In this case, dose map pixels are divided
by the simulated dose absorbed by the CTDI phantom. The basic trend of CTDI-normalized average dose increasing
with decreasing patient size (relative to the CTDI phantom) tends to agree with the SSDE correction factors.
Monte Carlo simulations with
patient-specific phantoms:
CTDI-Normalized Dose Maps
15 y/o
CTDIvol 32 = 6.3 mGy
Average
dose map value
Dose to 32 cm
CTDI phantom
10. A Monte Carlo tool is used to simulate the dose absorbed by the patient specific “virtual phantom” instead of the CTDI
phantom. This results in a patient specific dose map (in units of mGy). This example shows that the scan parameters
for a 13 day old resulted in less absorbed relative to a 15 year old.
Monte Carlo simulations with
patient-specific phantoms:
Individualized dose maps in mGy
13 day old
CTDIvol=1.5 mGy
15 year old
CTDIvol = 6.3 mGy
11. The CTDI of 2.5 mGy for a 13 day old and 6.3 mGy for a 15 year old would yield approximately the
same patient specific-dose map.
Monte Carlo simulations of
patient-specific phantoms
can be used to simulate new dose maps
13 day old
CTDIvol= 2.5 mGy
15 year old
CTDIvol = 6.3 mGy
Simulated
dose
maps
12. Morphological differences
between patient-specific & standard reference phantoms for
dosimetry simulation (Monte Carlo)
CT data sets are used to form patient specific virtual
phantom (previous slide). The size and shape of
organs and tissues can have wide variation.
Virtual phantoms do not extend
beyond reconstructed image
volume.
Organs are represented by patient generic,
fixed (stylized) geometric shapes.
Anatomy extends caudal-cranially,
enabling dose simulation and
scatter beyond scan range.
Oak Ridge National Lab Phantoms (Cristy)Virtual Patient (“Voxelized) Phantoms
newborn 1 YO 5 YO 10 YO 10 YO 5 YO 1 YO newborn
13. Acquisition of CT images
3
4
Monte Carlo simulations were
performed on voxelized image sets.
Dose Maps
displaying
CTDIvol
normalized
absorbed dose.
Organ doses can be segmented
from dose maps
CT image voxels were classified as 1 of 5
tissues based on attenuation
5
21
Background
Flowchartfor generation of dose maps: CT data acquisition,
creationof voxelized phantom,dose simulation
3
14. Dose Map:
Select
radiosensitive
organ or tissue
Average value of pixels
segmented in the organ
are used for organ
dose estimation
(in mGy)
Organ segmentation
Background
Patient-specificorgan doses can be estimatedwith dose maps
In standard reference phantoms such as those used for the DLP conversion factors, organs are defined
with fixed geometry using mathematical equations.
15. age 6 days 13 days 26 days 2 months
Lung dose 1.78 1.96 2.43 2.42
(mGy/mGy)
show patient-specific variability in organ doses that cannot
be shown in the Oak Ridge National Lab (ORNL)
references phantoms
Dose maps
Estimated lung dose (CTDI normalized) from patient specific dose maps varies from 1.78 to 2.43 mGy/mGy. CTDIvol
normalized organ doses simulated in the ORNL infant phantom (right) (new born) would not have any variability.
16. NRPB reference phantom (center [3]) extended the ORNL phantom concept (lower right) to include gender-based organs. The NRPB
phantoms were used by Jessen et al. (with IRCP 60 organ weighing factors) to determine widely used DLP conversion factors [5,11]
Standard Reference Phantoms
Can be modified to include additionalradiosensitiveorgans
17. Patient-specific voxelized phantoms
have featuresnot included in standard reference phantoms
Breast dose can be measured (green contours) in dose maps -- this tissue is represented in the NRCP phantoms (previous slide).
14 y/o female (left) and 15 y/o male (right) with approximately the same effective diameter (~27 mm). Bismuth shields (arrows) were
used in both exams (not represented in standard phantoms). Average lung dose is higher for the female patient due to relatively larger
lung parenchyma (lower beam attenuation).
18. Comparison of patient-specific &
reference phantom
methodsused for effectivedose calculation
Effective
Dose, Reference
Phantom
LEGEND:
CTDI = Computed Tomography Dose Index
DLP = Dose Length Product
ED = Effective Dose
ODi = Organ Dose
wi = tissue weighting factors, ICRP 60
compare
Effective Dose,
Patient-Specific
Phantom
ODi From Organ Segmentation
Dose Map
Monte Carlo
Simulation
(Scanner Specific)
Patient Data Set
CTDI, DLPscan
ED = k x DLPscan
Reference
Phantom
MonteCarlo
Simulation
ODi From Organ
Compartments
Dose
Map
CTDI, DLP
AAPM
Report
96.5
k
19. Background
Estimation of effectivedose for organ weighting factors
ED = ∑ wi x Odi
where
OD is the individual organ dose measured from non-patient specific
mathematical phantom or patient specific dose map
w is organ/tissue weighting factor (ICRP 60 or 103)
i = 13 (13 most radiosensitive organs)
The effective dose equivalent, therefore, represents a total body dose.
20. Relative Organ Dose Sensitivities, Wi
0
0.05
0.1
0.15
0.2
0.25
Relative Organ Sensitivities ICRP
(Used by both Pt. Specific and Std. Ref. Phantoms)
ICRP 60
ICRP 103
ICRP 60 and NRPB phantoms were used for DLP conversion coefficients (Jessen).
Patient-specific phantoms
Segmenting all the listed organs and
tissues for each individual voxelized
phantom can pose a challenge.
Standard reference phantoms
The NRPB phantoms do not include
all organs and tissues listed. And
they would need to be revised if the
ICRP adds new organs to the list.
21. Background
Determinationof DLPconversionfactors
Each body and age specific DLP conversion
factor (k factor in units of mSv mGy-1 cm-1)
was determined by dosimetry simulations
with varying DLP.
They are based on linear regression analysis
of body-region specific effective dose (from
the simulations, y-axis) and DLP (x-axis).
In this method, effective dose is assumed to be linearly proportional to DLP, i.e., E = DLP x k . DLP is linearly proportional to irradiated
scan length (includes helical over-ranging). For pediatrics, DLP is based on CTDI 16. Also, K-factors (i.e., DLP conversion) represent an
average over scanner types and are not gender specific. The organ dose weighting factors were described on the previous slide.
DLP input to Dose Simulation
Chest newborn
Slope = k, for each age
Chest 1 YO
Chest 5 YO
Chest 10 YO
EffectiveDose
asweightedsumoforgandoses
22. Effective dose using ICRP
weightingfactorscannot be patient-specific
• The organ sensitivity (weighting) factors are based on population data from survivors of
the atomic blast, where the sum of the weighting factors is one.
• A 0.12 value for lung tissue implies that the relative likelihood of developing lung cancer in
the population of blast survivors, in comparison with other listed organs, is 12%.
Therefore, any estimation of effective dose that uses these population based
weighting factors – patient-specific dose maps or DLP conversion k factors – cannot
be patient-specific.
Although effective dose is not patient specific, dose maps enable patient specific
organ dose estimates (next slide) and these increase the relative patient (as well
as scanner) specificity in comparison with DLP conversion factors.
23. Partial irradiation of an organ tends to decrease the organ
dose estimate. This is because organ dose is defined as the
average over the entire organ.
An advantage for the reference phantoms is that the caudal-
cranial range is not limited to a reconstructed scan volume as
with the voxelized phantom.
This can help estimate absorbed dose to partially irradiated
organs. Basing organ dose on only the fully irradiated voxels
will tend of overestimate the estimated organ dose.
Organ doses
partial irradiation, ICRPweighting factors
ICRP weighting factors are
based on full-body
irradiation. Tissues that
have wide distribution
throughout the body such as
red bone marrow are almost
certainly partially irradiated
in a CT examination.
partial irradiation of liver
scanlength
24. Summary comparison dose maps
and standard reference phantoms
Dose Map Method Standard Reference Phantom Method
Representation Voxelized Phantom Based on Data Set Four pre-defined geometric representation of organs
Morphology Patient-specific Not Patient Specific
Organs Organs must be segmented. Organs pre-defined mathematically
Caudal Cranial
End-effects
Not modeled (easily)
Extends beyond scan length to model partial organ
irradiation
Computation
Computed for each patient and each
examination
Can be pre-tabulated for set of examinations and stored
for future use
Material Models CT Numbers are mapped to ICRU 44 ICRP Publication 89
Effective Dose
Pt. specific organ dose can be used to
estimate eff. dose
Generic organ doses are used to determine DLP
conversion coefficients.
25. Estimation of CT dose is evolving …
10 cm CTDI phantom
Dose map sequence (z-axis) based on Monte
Carlo simulation with infant CT data set
26. Summary
Patient specific voxelized phantoms can represent complex, patient specific
anatomy and materials that are not easily represented in standard reference
phantom.
Organ doses estimated from patient specific dose maps ARE patient specific.
Patient-specific dose maps demonstrate the variability of organ doses and
highlight a key limitation of standard methods for estimating effective dose.
Use of more patient-specific methods to estimate organ and effective doses
could lead to better metrics and reporting for CT dose management. Effective
doses estimated from ICRP wt. factors and NOT patient specific, but EDose Maps is
more patient- and scanner-specific than EDLP.
27. Clinical Relevance
Patient-specific doses estimated by applying dosimetry
simulations to voxelized phantoms may have advantages when
patient morphology significantly differs from the reference
phantom.
Quantitative evaluation of patient-specific dose maps are
underway. This will lead to a better understanding how more
accurate dose estimate methods will impact CT radiation dose
management.
28. References1. Cristy M . Mathematical phantoms representing children of various ages for use in estimates of internal dose. Report no. ORNL/ NUREG/TM-367. Oak Ridge,
Tenn: Oak Ridge National Laboratory, 1980 .
2. Cristy M , Eckerman KF . Specifi c absorbed fractions of energy at various ages from internal photon sources. I. Methods. Report no. ORNL/TM-8381/V1. Oak
Ridge, Tenn: Oak Ridge National Laboratory, 1987 .
3. A Khursheed, Phd, M C Hillier, P C Shrimpton, Phd And B F Wall, Bsc, Influence of patient age on normalized effective doses calculated for CT examinations
4. Maria Zankl , Handbook of Anatomical Models for Radiation Dosimetry Edited by Xie George Xu and Keith F Eckerman , 3] Taylor & Francis 2009
5. American Association of Physicists in Medicine. The measurement, reporting and management of radiation dose in CT. Report 96. AAPM Task Group 23 of the
Diagnostic Imaging Council CT Committee. College Park, MD. American Association of Physicists in Medicine, 2008.
6. American Association of Physicists in Medicine. Size-specific dose estimates (SSDE) in pediatric and adult body CT examinations. Report 204. AAPM Task
Group 204. College Park, MD. American Association of Physicists in Medicine, 2011.
7. McCollough CH, et al., CT Dose Index and Patient Dose: They Are Not the Same Thing. Radiology: Volume 259:(2) 311-316.
8. Morgan HT., Dose reduction for CT pediatric imaging, Pediatr Radiol. 2002 Oct;32(10):724-8; discussion 751-4. Epub 2002 Aug 29.,
9. Adam C. Turner1 and Michael McNitt-Gray, The feasibility of patient size-corrected, scanner-independent organ dose estimates for abdominal CT exams, Med
Phys. 2011 Feb;38(2):820-9.
10. Boone JM, Strauss KJ, Cody DD, McCollough CH, McNitt-Gray MF, Toth TL, Goske MJ, Frush DP. Size-specific dose estimates (SSDE) in pediatric and adult
body CT examination. Report No. 204. 2011
11. Cynthia H. McCollough et al. How Effective Is Effective Dose as a Predictor of Radiation Risk?, AJR:194, April 2010
29. air
adipose tissue
lung tissue
soft tissue
cortical bone
A patient-specific (tomographic) virtual phantom (i.e., model) is created by “voxelizing” and automatically segmenting patients CT
dataset. Each voxel is assigned one of five material types based on an a priori, global HU classification intervals (ICRU 44). These
material types are also assigned mass density to compute absorbed dose.
The resulting virtual patient phantoms are used for dose simulation (Monte Carlo) and the results are referred to as Dose
Maps (next slide).
CT image for 6 day old Virtual patient phantom
Appendix I
Creation of a Patient-specificVoxelized Models
30. Limitations of CTDIvol
The CTDIvol reports scanner output based on a standard, fixed-sized
phantom (32 cm for body), not patient-specific dose. Therefore, dose is
over- and underestimated for patients significantly larger or smaller
(respectively) than the phantom. (see AAPM report 201)
EstimatedCTDIvol[mGy](120kV)
24 32 50
15
10
5
0
Patient diameter [cm]
Actual dose
for 24 cm
diameter patient
Reported dose
Actual dose
for 50 cm
diameter patient
31. DLPand Effective Dose
Effective dose (ED) parameter shown here is also based on the plastic CTDI phantoms. It is a risk-related quantity used to indicate equivalent whole body
exposure that includes DLP as well as other factors such as the radiation sensitivities of the various organs in the body, age, and gender.
Notes: 1) Effective dose using DLP conversion coefficients are estimated with averages over gender and age and therefore do not estimate risk for an
individual patient. 2) Reference for ED are based on estimates for annual background radiation (3 mSv). 3) Another method to compute ED is based on the
summation of organ dose estimates.
CTDI (mGy)
Dose Length Product
(mGy *cm)
Effective Dose (mSv)
Equation
or dose
calculation
method
CTDIvol
CTDIvol is
presently
measured
with
16 and 32 cm
phantoms
DLP = Irradiated Scan Length x CTDIvol
Helical scan length: the reconstructed scan
length plus helical over-ranging
Axial scan length: the reconstructed scan
length for one “axial shot” * number of axial
“shots”. (The CTDIvol accounts for “over-
beaming”).
k = conversion
coefficient for the
DLP method of
estimation
CONTENT ORGANIZATIONMorphology and tissues of a) reference phantoms used for organ doses and b) patients' voxelized data sets are compared. Review differences in body habitus (thin to obese), gender, and age.Methods for estimating dose to organs with a) pre-determined geometry in reference phantoms and b) segmentation of organs in patient-specific dose maps are compared. Review effects of organ size, shape and partial irradiation. Include comparisons with size-adjusted CTDI.Effective dose calculated by applying ICRP tissue weighing factors to a) reference-based organ doses and b) patient-specific organ doses are compared. Review implications for infant,1, 5, and 10 year-old DLP (“k”) conversion factors.SUMMARYEffective doses based on age-based reference phantoms are often used for relative dose comparisons. Use of more patient-specific methods to estimate organ and effective dose could lead to better metrics and reporting for CT dose management.
http://www.halls.md/chart/child-growth/pediatric.htmInfant 42 cm1 y/o 85 cm5 y/o 110 cm 10 y/o 140 cm
13 day old: 2.4 x 1.5 = 3.6 15 yr. old: 1.4 x 6.3 = 8.8
15 day old: 2.4 x 1.5 x X = 8.8 = 6.3 x 1.46.3/3.7 CTDI ratio = 1.7 = 2.4 / 1.4 CTDI Normalized Avg. Dose (un-weighted)