Pediatric Radiation Research Articles

Muscle-specific functional deficits and lifelong fibrosis in response to paediatric radiotherapy and tumour elimination.

BackgroundAs paediatric cancer survivors are living into adulthood, they suffer from the age‐related, accelerated decline of functional skeletal muscle tissue, termed sarcopenia. With ionizing radiation (radiotherapy) at the core of paediatric cancer therapies, its direct and indirect effects can have lifelong negative impacts on paediatric growth and maintenance of skeletal muscle. Utilizing our recently developed preclinical rhabdomyosarcoma mouse model, we investigated the late effects of paediatric radiation treatment on skeletal muscles from late adolescent (8 weeks old) and middle‐aged (16 months old) mice.MethodsPaediatric C57BL/6J male mice (3 weeks old) were injected with rhabdomyosarcoma cells into their right hindlimbs, and then fractionated irradiation (3 × 8.2 Gy) was administered to those limbs at 4 weeks old to eliminate the tumours. Radiation‐alone and tumour‐irradiated mice were assessed at either 8 weeks (3 weeks post‐irradiation) or 16 months (14 months post‐irradiation) of age for muscle physiology, myofibre characteristics, cell loss, histopathology, fibrosis, inflammatory gene expression, and fibrotic gene expression.ResultsMice that received only paediatric radiation demonstrated reduced muscle mass (−17%, P < 0.001), muscle physiological function (−25%, P < 0.01), muscle contractile kinetics (−25%, P < 0.05), satellite cell number (−45%, P < 0.05), myofibre cross‐sectional area (−30%, P < 0.0001), and myonuclear number (−17%, P < 0.001). Paediatric radiation increased inflammatory gene expression, increased fibrotic gene expression, and induced extracellular matrix protein deposition (fibrosis) with tumour elimination exacerbating some phenotypes. Paediatric tumour‐eliminated mice demonstrated exacerbated deficits to function (−20%, P < 0.05) and myofibre size (−17%, P < 0.001) in some muscles as well as further increases to inflammatory and fibrotic gene expression. Examining the age‐related effects of paediatric radiotherapy in middle‐aged mice, we found persistent myofibre atrophy (−20%, P < 0.01), myonuclear loss (−18%, P < 0.001), up‐regulated inflammatory and fibrotic signalling, and lifelong fibrosis.ConclusionsThe results from this paediatric radiotherapy model are consistent and recapitulate the clinical and molecular features of accelerated sarcopenia, musculoskeletal frailty, and radiation‐induced fibrosis experienced by paediatric cancer survivors. We believe that this preclinical mouse model is well poised for future mechanistic insights and therapeutic interventions that improve the quality of life for paediatric cancer survivors.

Reducing Anesthesia Use Among Pediatric Radiation Therapy Patients

Reducing Anesthesia Use Among Pediatric Radiation Therapy Patients

High Prevalence of Gene Fusions and Copy Number Alterations in Pediatric Radiation Therapy-Induced Papillary and Follicular Thyroid Carcinomas.

Background: Childhood cancer survivors and bone marrow transplant recipients treated with radiation therapy (RT) are at increased risk for subsequent thyroid cancer. However, the genetic landscape of pediatric thyroid cancer, both primary and RT-induced, remains poorly defined, as pediatric papillary thyroid carcinoma (PTC) has been understudied compared with adults and data on pediatric follicular thyroid carcinoma (FTC) are virtually nonexistent. The objective of this study was to characterize and compare the molecular profiles of pediatric RT-induced PTC and FTC cases with primary pediatric thyroid cancers. Methods: A total of 41 differentiated thyroid carcinomas (11 RT cases and 30 primary cases) from 37 patients seen at Phoenix Children's Hospital between January 1, 2010 and December 31, 2019 were evaluated by targeted next-generation sequencing and/or BRAF immunohistochemistry. Results: Eighty-six percent (6/7) of RT-PTC harbored a gene fusion (GF) compared with 56% (14/25) of primary PTC; 14% (1/7) of RT-PTC had a single-nucleotide variant (SNV; specifically, a point mutation in the DICER1 gene) compared with 44% (11/25) of primary PTC (all of the latter had the BRAFV600E mutation). An exceedingly rare ROS1 fusion was identified in a child with RT-PTC. With respect to FTC, copy number alterations (CNAs) were seen in 75% (3/4) of RT cases compared with 40% (2/5) of primary cases. None of the RT-FTC had SNVs compared with 100% (5/5) of primary FTC. Conclusions: In children, the molecular profile of subsequent RT-induced thyroid cancers appears to differ from primary (sporadic and syndromic) cases, with a high prevalence of GFs in RT-PTC (similar to PTC occurring after the Chernobyl nuclear reactor accident) and CNAs in RT-FTC. A better understanding of the molecular mechanisms underlying these cancers may lead to more accurate diagnosis, prognosis, and treatment, as some of the genomic alterations are potentially targetable.

Establishment of diagnostic reference level for computed tomography of head pediatrics in Morocco: A pilot study

Pediatric patients are well documented to be at higher risk of developing radiation-induced cancer than the average adult. This pilot study aims to estimate the radiation doses to pediatric patients during head Computed Tomography (CT), in order to establish local Diagnostic Reference Level (DRL).Data from 300 pediatric head CT examinations from 6 public hospitals were analyzed. The age group concerned is 5–10 years. The CT facilities were 64, 16, 4 and dual slice type. CT data included scanner acquisition parameters, the number of series, use of the contrast medium, rotation time, slice thickness, as well as the displayed CT Dose Index (CTDIvol) and the Dose Length Product (DLP). The effective dose and DRL were evaluated using the formalism and conversion factor of the International Commission on Radiological Protection (ICRP).The overall mean CT dose per procedure from different facilities was 44,97 mGy, 883,67 mGy.cm and 2,81 mSv for CTDIvol, DLP and effective dose, respectively. The mean third quartile dose per head CT procedure from all facilities was 40,94 mGy and 969,90 mGy.cm cm for CTDI and DLP, in that order. These results proved that pediatric patients are exposed to unnecessary doses of radiation during CT examination in public healthcare institution of Morocco.The DRL obtained was slightly higher than those established in some countries. Pediatric radiation dose per procedure indicated a wide variation between various hospitals and even in the same hospital for different patients. This pilot study showed the need for practices unification and radiation doses optimization during CT scan acquisition for pediatric patients in radiology departments.

Impact of Pediatric Radiation Oncology With Movie Induced Sedation Effect (PROMISE) on Patient Movement and General Anesthesia Use in Pediatric Radiation Therapy

Pediatric radiation therapy (RT) often requires daily anesthesia to ensure precise immobilization for safe and accurate treatment. Unfortunately, repeated anesthesia can be detrimental to patient health and quality of life, and provides significant logistical and financial burden. PROMISE (Pediatric Radiation Oncology with Movie Induced Sedation Effect) is an interactive incentive-based movie system that allows for real time monitoring of patient motion and automatic shutting off of the beam and video if the patient moves outside of defined parameters. We hypothesize that PROMISE will result in minimal patient movement during RT and an overall decrease in the need for general anesthesia in young children (ages 3-7).PROMISE integrates a movie system involving wireless video streaming to a low attenuation screen directly in front of the patient with a video surveillance gating module (AlignRT) for real time monitoring and behavior training. Starting in the beginning of 2020, this system was available for all children < 12 years old undergoing RT at our institution. For patients treated with PROMISE, AlignRT monitoring data was collected and analyzed to determine patient motion. We compared frequency of anesthesia use after implementation of PROMISE to the 2 years' prior at our institution to estimate reduction in anesthesia use per age group.PROMISE was successfully implemented in 21 children, the majority (76%) who were 7 years or younger and most likely would have otherwise required daily anesthesia. Patient movement during RT with PROMISE was minimal, with in-treatment variation of ∼1.2 mm (0.8 mm standard deviation) from the reference baseline. Prior to implementation of PROMISE (2018-19), 100% of kids below the age of 3 (6/6), 70% of kids ages 3-7 (14/20), and 14% of kids ages 8 to 11 (4/28) needed general anesthesia. After PROMISE implementation (2020), 100% of kids below the age of 3 (5/5), 40% of kids ages 3-7 (8/20), and 8% of kids ages 8-11 (1/13) needed general anesthesia. When analyzed per fraction, after PROMISE, 100% below the age of 3 (76/76), 29% ages 3-7 (90/315), and < 1% ages 8-11 (1/221) required general anesthesia. On per patient comparison, PROMISE resulted in a 30% absolute benefit in those 3-7 years old, with 70% previously requiring anesthesia to only 40% after the implementation of PROMISE.PROMISE resulted in a 30% absolute reduction in general anesthesia use for children ages 3-7. Further, patient movement during RT with PROMISE was minimal, within acceptable standards. The real time motion monitoring with automatic safety shutoff and behavioral training make PROMISE a unique and attractive alternative to general anesthesia. Further prospective clinical data is necessary to prove the safety and efficacy of PROMISE in pediatric RT.

General Anesthesia for Pediatric Radiotherapy in the Era of COVID-19

Purpose/Objective(s)Managing pediatric patients (pts) requiring daily general anesthesia (GA) for radiation (RT) in the setting of COVID-19 is complex, due to both the aerosolizing nature of GA procedures and the risk of cardiopulmonary complications for infected pts. We hypothesized that deliberate management of pts requiring GA for RO during COVID-19 would allow safe operations to continue.Materials/MethodsPediatric pts treated under GA at our tertiary hospital from 3/1/2020 to 1/29/2021 were identified; development of COVID-19 precautions began on 3/1/2020. Pts underwent COVID testing prior to their first treatment and thrice weekly (MWF) during treatment. Pts were accompanied by only one designated adult caregiver through the entire RT course; caregivers were verbally screened; and staff personal protective equipment (PPE) included surgical mask and eye protection. For COVID+ pts, RT was delivered at the end of day; a negative pressure room was used for GA induction and recovery; staff PPE included N-95 masks or powered air purifying respirators (PAPRs); and separate physician/nurse teams were designated for in-room vs. out-of-room pt management.Results78 pediatric pts received RT under GA (vs. 69 pts over the same prior-year timeframe). From 3/1/2020-1/29/2021, mean age was 4.9 y (range 5.5 m - 19.0 y), 41/78 (52.6%) were male, and 2/78 (2.6%) received 2 courses of RT under GA, for a total of 80 courses. 24/80 (30.0%) courses were delivered to the chest, abdomen, and/or pelvis, 21/80 (26.3%) craniospinal axis, 17/80 (21.3%) brain, 9/80 (11.3%) total body irradiation, 5/80 (6.3%) head/neck, and 4/80 (5%) other. 64/80 (80%) of courses were delivered with curative intent. 39/80 (48.8%) used proton therapy, 18/80 (22.5%) photons, and 23/80 (28.8%) both modalities. Mean number of treatment fractions was 22.2 (range 1-40). 2/78 pts (2.6%) tested positive for COVID-19, both asymptomatic. Early in the pandemic (4/2020), pt 1 (a 3 yo female with neuroblastoma) had simulation delay for known household contact; after 5 weeks, COVID testing returned positive after the first day of RT. A 2 d treatment interruption was required to finalize institutional COVID guidelines, and treatment continued without incident. Because eye protection was not yet routinely used early in the pandemic, 17 staff were quarantined, but no further staff exposures occurred after precautions for the positive test were implemented. Later in the pandemic (1/2021), pt 2 (a 3 yo male with relapsed medulloblastoma) tested positive on initial COVID testing, requiring 10 d of COVID precautions for treatment; no staff exposures occurred. No caregivers screened positive, and no children presented for treatment without the designated parent.ConclusionWith careful multidisciplinary planning to mitigate COVID-19 risk, pediatric RT with GA was carried out for a large pt volume without widespread infection, and without increased toxicities from either GA or RT. Frequent pt COVID testing and attention to PPE limited staff exposures.

Determining Pediatric Radiotherapy Capacity in Mexico

A 2019 report demonstrated that Mexico and Central America have the highest total incidence of childhood cancers in the Western Hemisphere. Mexican children face disparities in cancer outcome. In Mexico, the 5-year survival estimates for ependymoma and intracranial germ cell tumors, two pediatric brain tumor types, are approximately 20%, which is dramatically lower than the survival outcomes reported in the US of 80% or higher. We sought to determine the self-identified treatment patterns, needs, and concerns of Mexican radiation oncologists for pediatric cancer management.Stakeholder planning began the summer of 2019. Partnering with local experts and the national Sociedad Mexicana de Radioterapeutas (SOMERA), we reviewed and designed a Spanish-language survey to ascertain pediatric radiotherapy capacity. The survey consisted of 35 questions and was distributed through the SOMERA listserv with promotion on social media. The survey was open from July 11 through August 30, 2020. Descriptive statistics were conducted. For frequencies, we report median (range). Surveys were stored in Qualtrics.A total of 94 radiation oncologists attempted, and 79 completed, the survey and identified as working in Mexico, representing 20 different cities. Of those, 58 (73%) responded saying they had treated a pediatric patient within the past year with median 9 years of practice (1-38). Forty-four (76%) felt comfortable with treating a pediatric patient, and 36 (62%) said they were familiar with national protocols for pediatric cancer treatment. The median number of pediatric cases seen in the past year by respondents was 9.5 (0 - 195). The three most common tumors treated were Hodgkin lymphoma (2; 0-21), medulloblastoma (1.5; 0-20), and Wilms tumor (1; 0-20), respectively. The median percentage of pediatric patients treated palliatively was 10%. Also, 26% responded having access to a multidisciplinary tumor board. Regarding supports, the majority had access to nutrition, rehabilitation, endocrinology, and anesthesia; 14% had access to fertility services, 27% had access to neurocognitive support, 11% responded noting no support, and only 1 respondent had child-life support. When asked what challenges they face as physicians, 20% expressed a lack of treatment spots and extended delay to new start, and 16% noted challenges with access to pediatric oncology and multidisciplinary teams.We present the first national survey of Mexican radiation oncologists with an intent to explore pediatric radiotherapy capacity. Through partnership with SOMERA, many centers were represented across the country. The majority of respondents who had treated a child patient felt comfortable doing so. Limited resources include access to fertility, child-life, and neurocognitive services. Wait times and lack of treatment spots were the most common physician challenges identified by respondents.

Impact of Cardiac Substructure Dosimetry on Late Cardiac Risk: A Report From the Childhood Cancer Survivor Study (CCSS)

<h3>Purpose/Objective(s)</h3> Prior estimates of radiation (RT)-associated cardiac disease risk in childhood cancer survivors are based on estimates of RT dose to the entire heart. We aimed to evaluate whether cardiac substructure RT dosimetry improves estimation of late cardiac disease risk. <h3>Materials/Methods</h3> We determined the cumulative incidence of CTCAE grade 3 – 5 cardiac disease (heart failure, coronary artery disease, valvular disease, arrhythmia, or pericardial disease) among 25,481 5-year survivors from CCSS diagnosed 1970 – 1999. Median age at diagnosis was 6.1 years (range 0 – 20) and at last follow-up was 29.8 years (5.6 – 65.9). We considered a single composite endpoint of any cardiac disease to best identify which substructures to prioritize for avoidance in RT planning to minimize the absolute risk of cardiac disease. We reconstructed RT fields for irradiated survivors (n = 12,228) on an age-scaled phantom and estimated mean RT dose to the heart, four chambers, four valves, and the left anterior descending (LAD), circumflex, main (LM), and right coronary arteries. Adjusted piecewise exponential models (including cumulative anthracycline dose) evaluated associations between mean RT dose to each structure and outcomes. Each substructure was individually added to a model with mean whole heart RT dose and the fit was assessed via the likelihood-ratio test to ascertain which substructures improved prediction of cardiac risk beyond whole heart dose. <h3>Results</h3> At 35 years from diagnosis, the cumulative incidence of any cardiac disease was 7.0% (95% CI 6.5 – 7.6). When adding each substructure separately to a model with mean whole heart dose, the addition of mean LAD (χ² = 29.1) or LM (χ² = 34.6) RT dose significantly improved the risk estimation of any cardiac disease (<i>P</i> < 0.01). Among survivors with mean whole heart doses < 10 Gy, increasing mean LAD but not mean LM doses significantly increased risk of late cardiac disease. Even among those with a mean heart dose of < 5 Gy, mean LAD dose of ≥10 Gy was associated with a more than three-fold increased risk of cardiac disease (Table 1). <h3>Conclusion</h3> Even among survivors with low mean heart doses (< 5 Gy), mean LAD doses ≥10 Gy increased risk of cardiac disease. Thus, for pediatric RT planning we recommend limiting mean LAD dose to < 10 Gy, even when mean heart dose constraints can be achieved. Table 1. Relative rate of grade 3 – 5 cardiac disease in childhood cancer survivors by RT dose to the heart and LAD.

Radiation dose levels of thoracic-lumbar spine CT in pediatric trauma patients and assessment of scan parameters for dose optimization.

CT is frequently used for assessing spinal trauma in children. To establish the local diagnostic reference levels of spine CT examinations in pediatric spinal trauma patients and analyze scan parameters to enable dose optimization. In this retrospective study, we included 192 pediatric spinal trauma patients who underwent spine CT. Children were divided into two age groups: 0-10years (group 1) and 11-17years (group 2). Each group was subdivided into thoracic, thoracolumbar and lumbar CT groups. CT acquisition parameters (tube potential, in kilovoltage [kV]; mean tube current-time product, in milliamperes [mAs]; reference mAs; collimated slice width; tube rotation time; pitch; scan length) and radiation dose descriptors (volume CT dose index [CTDIvol] and dose-length product [DLP]) were recorded. The CTDIvol and DLP values of spine CTs obtained with different tube potential and collimated slice width values were compared for each group. CTDIvol and DLP values of thoracolumbar spine CTs in group 1 and lumbar spine CTs in group 2 were significantly lower in CTs acquired with low tube potential levels (P<0.05). CTDIvol and DLP values of thoracolumbar spine CTs in both groups and lumbar spine CTs in group 2 acquired with high collimated slice width values were significantly lower than in corresponding CTs acquired with low collimated slice width values (P<0.05). Pediatric spine CT radiation doses can be notably reduced from the manufacturers' default protocols while preserving image quality.

Dr. Edith H. Quimby: A pioneering medical physicist and educator with outstanding contributions in radiation dosimetry

Dr. Edith H. Quimby: A pioneering medical physicist and educator with outstanding contributions in radiation dosimetry

European clinical trials in paediatric radiation oncology

Radiotherapy is an important part of multimodality treatment protocols for around a third of children and young people with malignant disease.1 Although ionising radiation has been available in some form for around a century, technology has been continuously refined and developed.2 Together with a better understanding of pathology and molecular biology of cancer through sequential clinical trials, improved radiation technology has led to a transformation of radiotherapy in the past few decades. Paediatric radiation oncology has also evolved and taken advantage of these technical advances.

Establishing a pediatric radiation oncology department in a low- and middle-income country: Major challenge in implementing the Global Initiative for Childhood Cancer.

Establishing a pediatric radiation oncology department in a low- and middle-income country: Major challenge in implementing the Global Initiative for Childhood Cancer.

PD-0757 Low dose cone beam CT for paediatric image-guided radiotherapy: how much dose is enough?

PD-0757 Low dose cone beam CT for paediatric image-guided radiotherapy: how much dose is enough?

PO-1976 Has the Covid-19 Pandemic increased willingness to engage with remote collection of outcome data?

Purpose or Objective: Remote healthcare applications have been developing over many years, however clinical implementation has been cautious. As society has embraced technology during the Covid-19 pandemic, the question is: have attitudes towards remote healthcare technology also changed? One particular aspect of healthcare that could be addressed remotely is the collection of patient reported outcome measures (PROMs) using a digital voice assistant (DVA) such as the Amazon Echo (Alexa). This could improve both the frequency and quality of data collected. Materials and Methods: A questionnaire was developed to evaluate patient and carer opinions on using a DVA to report radiotherapy-related side effects. This was distributed to the adult patients in the radiotherapy department in February 2019 and to the Teenager, Young Adult and Paediatric radiotherapy department in mid 2019. It was redistributed in September 2020, allowing a pre/post Covid-19 comparison. To maximise engagement with the questionnaire, it was decided to ask a small number of simple questions. These four questions sought to ascertain whether the respondent was a patient or carer, respondent age (decade grouping), how knowledgeable they were about the Amazon Echo, and how willing they would be to participate in a hypothetical study in which they would use an Amazon Echo to record the side effects they experienced as a result of their cancer treatment. A comments box was included to allow participants to convey additional information. Results: 85 completed questionnaires were collected in 2019 and 43 in 2020. The median age of the initial survey cohort was 60-69 years old whilst for the second cohort was 50-59 years old. The slight difference in median age of the cohorts is likely a reflection on modifications to clinical practice due to Covid-19. 16% of the initial cohort and 19% of the second cohort were carers. 67% of the initial cohort responded that they had some or good knowledge of Amazon Echo, this increased to 84% in the second cohort (fig. 1). Willingness to participate was highest in the group of patients with good knowledge. 44% of the initial cohort were willing to take part in a study using an Amazon Echo to record side effects, increasing to 58% in the subsequent cohort (fig. 2). However, the percentage of respondents who were not willing to take part also increased from 32% to 37% with a reduction in the number of respondents who didn’t know (25% to 5%). Willingness to participate varied with age. Comments were diverse and included concerns about using technology and data security but also positive comments on the potential to reduce hospital visits. (Figure Presented) Conclusion: Overall, the survey results indicate an increased knowledge of DVA. There was also an increased willingness to engage with a DVA for remote collection of radiotherapy outcome data following the first wave of the Covid-19 pandemic.

Utility of Multi-institutional Pediatric Chart Rounds in the Age of Telemedicine.

Pediatric radiation oncology remains a highly subspecialized field owing to a relatively lower incidence rate of pediatric malignancies, which account for less than 5% of total cancer cases annually in the United States.1,2 Another challenge of treating pediatric malignancies is the diverse profile of tumors, ranging from hematologic malignancies to a heterogenous set of soft tissue and bone sarcomas. These inherent issues result in consistently low case numbers for the average resident,3-5 with almost one-third of senior residents recently reporting insufficient training in pediatric radiation oncology.

Evaluation of pediatric radiation doses in computed tomography procedures in the Kingdom of Saudi Arabia

Computed tomography (CT) frequency is approximately 11% of medical radiological procedures. Nevertheless, CT examinations contribute up to 70% collective doses. CT procedures carried out in pediatric patients represent 33% of CT procedures. This study aimed to assess pediatric doses during chest and abdomen procedures and estimated the projected radiogenic risk. In total, 83 pediatric were divided into four groups, according to their age (years). The patients were ≤six months, six months - ≤3 years, 4 - ≤ 6 years and, 7 - ≤ 15 years. The mean and range of DLP (mGy.cm) and CTDIvol (mGy) for pediatric CT chest were 42 (33–52) and 2 (1.9–2.2), respectively. The mean and range of DLP (mGy.cm) and CTDIvol (mGy) for pediatric CT abdomen pelvic region were 116 (105–129) and 3.8 (3.7–3.9), in that order. Even though pediatric' radiation doses are below the published diagnostic reference levels (DRL), additional dose reduction is required and achievable if the imaging protocol is adjusted according to the child size.

Effects of immersive virtual reality exposure in preparing pediatric oncology patients for radiation therapy.

Procedural anxiety in children undergoing radiation therapy (RT) is common and is associated with poor procedural compliance and an increased used of general anaesthesia (GA). There is emerging evidence that Virtual Reality (VR) technology may reduce medical procedural distress through realistic and educative exposure to actual procedures via virtual simulation. To examine the feasibility, acceptability and efficacy of an Immersive VR exposure intervention aimed at reducing anxiety and enhancing preparedness for pediatric patients undergoing radiation therapy, and their parents. A convenience sample of patients (6-18years) scheduled for RT, and their parent caregivers, were recruited consecutively over a 14-month period. Patients were exposed to a virtual simulation of both CT Simulation (Phase 1) and RT (Phase 2), prior to these procedures occurring. Pre-and-post VR intervention measures (anxiety, health literacy) were administered across multiple time points. GA requirement following VR intervention was also recorded. Thirty children and adolescents were recruited (88% participation rate). High VR acceptability and satisfaction was reported by patients, parents and radiation therapists. There were minimal adverse effects associated with VR. The VR intervention was found to improve children's understanding of the RT procedures (health literacy) and lower pre-procedural child and parental anxiety. Only one child in the study required GA (3.33%). This study provides novel and preliminary support for utilizing VR to prepare children and families for RT. Subsequent implementation of VR into routine paediatric RT has the potential to improve clinical and operational outcomes.

Evaluation of patients radiation dose in computed tomography paranasal sinuses in children

This study evaluates pediatric patients' radiation doses during paranasal CT procedures. A total of 48 (28 (58.3%) male, 20 (41.7%) female pediatric patients have undergone CT paranasal sinuses (PNS) in three consecutive years. The pediatric patient's radiation exposure was estimated based on justified medical procedures. Calibrated multidetector CT (MDCT) machine (Siemens Somatom Sensation 64 (64 detectors)) was used for all the procedures. All the PNS procedures were conducted at Riyadh Care Hospital. The parameters included the volume CT dose index (CTDIvol (mGy) and dose length product (DLP) (mGy.cm). The mean, standard deviation and range of the volume CTDI (mGy) and DLP (mGy.cm) for the 3 particular years were (2018) 9.36 (3.49–34.88), 196.1 (56.27–812.1), (2019) 16.9 (3.74–45.8), 333.9 (55.8–832.9) and (2020) 22.8 (4.03–45.8), 474.9 (63.9–979.02), respectively. Patients' doses were lower compared to most previous studies. However, proper exposure parameters and precise justification will reduce pediatric radiation doses during CT-PNS significantly.

Paediatric radiation dose and cancer risk associated with body effective diameter during CT thorax examination

Paediatric patients are considered vulnerable to radiation exposure and have a greater risk of developing radiation-induced cancers due to active growth cells. Radiation dose from a CT examination is the highest among other imaging modalities and can become harmful if unoptimised. Thus, the aim of this study is to evaluate the influence of paediatric size on SSDE value and to estimate cancer risk occurrence in specific organs of paediatric patients receiving CT chest examination. Data such as volume-weighted CT dose index (CTDIvol), dose length product (DLP) and patient's demography were retrospectively collected from a 64-slice CT scanner (Siemens Somatom Definition AS+) at University Malaya Medical Centre. A total of 120 patients were categorised into four age groups: G1 (0 – < 1 years), G2 (1 – < 5 years), G3 (5 – < 10 years), and G4 (10 – < 15 years). SSDE value was estimate in accordance with the American Association of Physicists, 2011 in Medicine (AAPM) report 204. The effective dose (E) and SSDENCICT obtained from National Cancer Institute Dosimetry System (NCICT) were then compared to the conventional SSDE value. The highest value of CTDIvol, DLP and E were found in group G4 with 4.9 ± 2.5, 185.0 ± 140.8, and 4.2 ± 2.0, respectively. Moreover, there is only slightly different of SSDE value between the G1 and G2 groups with a factor of 0.91. No significant difference (p > 0.05) was observed between the SSDEAAPM and SSDENCICT across all age groups. The cancer risk estimated shows thyroid organs receives the highest probability of cancer incidence in both the genders, which was calculated to be 2.1 for males and 3.9 for females per 100,000 procedures, respectively. Nevertheless, adequate justification of paediatric CT scans and dose optimisation are required to reduce unnecessary exposure and radiation-induced risks.

A survey of the pediatric radiation doses during multiphase abdominal computed tomography examinations

This work investigates pediatric patients' radiation doses during multiphasic computed tomography (CT) abdomen procedures in six hospitals. A total of 58 (14 (24% females)) and 44 males (44, 76%) underwent CT single or multiphase procedures. A single phase and triple phase CT examination were carried a wide range of clinical indications, including renal and digestive systems pathologies. All procedures were performed at six radiology departments. Three departments are equipped with 16 slice CT machines, and the other three departments are equipped with 160, 128 and 16 slice CT machines. The overall 3rd quartile values for CTDIvol (mGy) and DLP (mGy.cm) were 8.6 ± 4.7 (mGy) and 1580 ± 594.64 (mGy.cm) per CT abdomen procedure. The current study indicates the need for dose optimization for pediatric patients by establishing proper imaging protocols based on the international guidelines. The variation in patients’ doses is attributed to variation in the imaging protocols, scan length and number of phases performed per pediatric CT abdomen procedure.