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Heterogeneity of dose distribution has been shown at different spatial scales in diagnostic nuclear medicine. In cancer treatment using new radiopharmaceuticals with alpha-particle emitters, it has shown an extensive degree of dose heterogeneity affecting both tumour control and toxicity of organs at risk. This review aims to provide an overview of generalized internal dosimetry in nuclear medicine and highlight the need of consideration of the dose heterogeneity within organs at risk. The current methods used for patient dosimetry in radiopharmaceutical therapy are summarized. Bio-distribution and dose heterogeneities of alpha-particle emitting pharmaceutical 223Ra (Xofigo) within bone tissues are presented as an example. In line with the strategical research agendas of the Multidisciplinary European Low Dose Initiative (MELODI) and the European Radiation Dosimetry Group (EURADOS), future research direction of pharmacokinetic modelling and dosimetry in patient radiopharmaceutical therapy are recommended.

PURPOSE: (177)Lu-DKFZ-PSMA-617 is a promising treatment for patients with metastatic prostate cancer. Specific dosimetry for each patient is an important factor in planning the patient’s treatment process. This study aimed to perform an image-based absorbed dose calculation for the treatment of metastatic prostate cancer with (177)Lu-DKFZ-PSMA-617. METHODS: The individualized patient dosimetry calculations were based on whole-body planar scintigraphy images acquired in 10 patients with a mean age of 71.4 ± 6.07 years (range 63–85 years) at approximately 0–2 h, 4–6 h, 18–24 h, and 36–48 h after administration of the mean 6253 ± 826.4 MBq (range 5500–7400 MBq) of (177)Lu-DKFZ-PSMA-617. Time-activity curves were generated for various organs. For count conversion to activities, calibration factors were calculated. Finally, the absorbed dose for an individual cycle was calculated using IDIAC-DOSE 2.1 software. RESULTS: On average, the calculated absorbed dose for the kidneys and salivary glands were 0.46 ± 0.09 mGy/MBq and 0.62 ± 0.07 mGy/MBq, respectively. CONCLUSIONS: Based on the results, the(177)Lu-PSMA-617 therapy is a safe method for the treatment of castration-resistant prostate cancer patients. Large inter-individual variations in organ dose were found, demonstrating the need for patient-specific dosimetry and treatment planning.

Radioactive iodine is commonly used for the treatment of different thyroid conditions since the 1940s. The EANM has developed a standard pre-therapeutic procedure to estimate patient specific thyroid uptake at treatment of benign thyroid diseases. The procedure which models the time dependent fractional thyroid uptake is based on a two-compartment fitting system, one representing the thyroid and the other the blood. The absorbed dose is however only estimated for the thyroid and not for any other organ in the body. A more detailed biokinetic model for iodine is given by the ICRP and includes an iodide transport in the whole body. The ICRP model has 30 different compartments and 48 transfer coefficients to model the biokinetics of iodide and to model different transfer for inorganic iodide and organic iodine. The ICRP model is a recirculation iodine model, and the optimization is performed on the whole model and not exclusively on the thyroid as in the EANM procedure. Combining the EANM method and the ICRP model gives both patient specific estimations of thyroid uptake and retention and include most organs in the body. The new software gives both an improved patient specific dosimetry for the thyroid and an estimation of the absorbed dose to non-target organs and tissues like kidneys, urinary bladder, stomach wall, and uterus. Using the method described in this paper, the repercussions on the daily routines will be minimal.

Background The COVID-19 pandemic challenges our ability to safely treat breast cancer patients and requires revisiting current techniques to evaluate optimal strategies. Potential long-term sequelae of breast radiation have been addressed by deep inspiration breath-hold (DIBH), prone positioning, and four-dimensional computed tomography (4DCT) average intensity projection (AveIP)-based planning techniques. Dosimetric comparisons to determine the optimal technique to minimize the normal tissue dose for left-sided breast cancers have not been performed. Methods Ten patients with left-sided, early-stage breast cancer undergoing whole breast radiation were simulated in the prone position, supine with DIBH, and with a free-breathing 4DCT scan. The target and organs at risk (OAR) contours were delineated in all scans. Target volume coverage and OAR doses were assessed. One-way analysis of variance (ANOVA) and Kruskal-Wallis one-way ANOVA were used to detect differences in dosimetric parameters among the different treatment plans. Significance was set as p < 0.05. Results We demonstrate differences in heart and lung dose by the simulation technique. The mean heart doses in the prone, DIBH, and AveIP plans were 129 cGy, 154 cGy, and 262 cGy, respectively (p=0.02). The lung V20 in the prone, DIBH, and AveIP groups was 0.5%, 10.3% and 9.5%, respectively (p

Background The aim of this study was to compare a commercial dosimetry workstation (PLANET® Dose) and the dosimetry approach (GE Dosimetry Toolkit® and OLINDA/EXM® V1.0) currently used in our department for quantification of the absorbed dose (AD) to organs at risk after peptide receptor radionuclide therapy with [177Lu]Lu-DOTA-TATE. Methods An evaluation on phantom was performed to determine the SPECT calibration factor variations over time and to compare the Time Integrated Activity Coefficients (TIACs) obtained with the two approaches. Then, dosimetry was carried out with the two tools in 21 patients with neuroendocrine tumours after the first and second injection of 7.2 ± 0.2 GBq of [177Lu]Lu-DOTA-TATE (40 dosimetry analyses with each software). SPECT/CT images were acquired at 4 h, 24 h, 72 h and 192 h post-injection and were reconstructed using the Xeleris software (General Electric). The liver, spleen and kidneys masses and TIACs were determined using Dosimetry Toolkit® (DTK) and PLANET® Dose. The ADs were calculated using OLINDA/EXM® V1.0 and the Local Deposition Method (LDM) or Dose voxel-Kernel convolution (DK) on PLANET® Dose. Results With the phantom, the 3D calibration factors showed a slight variation (0.8% and 3.3%) over time, and TIACs of 225.19 h and 217.52 h were obtained with DTK and PLANET® Dose, respectively. In patients, the root mean square deviation value was 8.9% for the organ masses, 8.1% for the TIACs, and 9.1% and 7.8% for the ADs calculated with LDM and DK, respectively. The Lin’s concordance correlation coefficient was 0.99 and the Bland–Altman plot analysis estimated that the AD value difference between methods ranged from − 0.75 to 0.49 Gy, from − 0.20 to 0.64 Gy, and from − 0.43 to 1.03 Gy for 95% of the 40 liver, kidneys and spleen dosimetry analyses. The dosimetry method had a minor influence on AD differences compared with the image registration and organ segmentation steps. Conclusions The ADs to organs at risk obtained with the new workstation PLANET® Dose are concordant with those calculated with the currently used software and in agreement with the literature. These results validate the use of PLANET® Dose in clinical routine for patient dosimetry after targeted radiotherapy with [177Lu]Lu-DOTA-TATE.

Effective dose (E) has been developed by the International Commission on Radiological Protection (ICRP) as a dose quantity with a link to risks of health detriment, mainly cancer. It is based on reference phantoms representing average individuals, but this is often forgotten in its application to medical exposures, for which its use sometimes goes beyond the intended purpose. There has been much debate about issues involved in the use of E in medicine and ICRP is preparing a publication with more information on this application. This article aims to describe the development of E and explain how it should be used in medicine. It discusses some of the issues that arise when E is applied to medical exposures and provides information on how its use might evolve in the future. The article concludes with responses to some frequently asked questions about uses of E that are in line with the forthcoming ICRP publication. The main use of E in medicine is in meaningful comparison of doses from different types of procedure not possible with measurable dose quantities. However, it can be used, with appropriate care, as a measure of possible cancer risks. When considering E to individual patients, it is important to note that the dose received will differ from that assessed for reference phantoms, and the risk per Sv is likely to be greater on average in children and less in older adults. Newer techniques allow the calculation of patient-specific E which should be distinguished from the reference quantity.

Purpose In interventional cardiology, patients may be exposed to high doses to the skin resulting in skin burns following single or multiple procedures. Reviewing and analysing available software (online or offline) may help medical physicists assessing the maximum skin dose to the patient together with the dose distribution during (or after) these procedures. Method and results Capabilities and accuracy of available software were analysed through an extensive bibliography search and contacts with both vendor and authors. Their markedly differed among developers. In total, 22 software were identified and reviewed according to their algorithms and their capabilities. Special attention was dedicated to their main features and limitations of interest for the intended clinical use. While the accuracy of the 12 software products validated with measurements on phantoms was acceptable (within±25%), the agreement was poor for the two products validated on patients (within±43% and±76%, respectively). In addition, no software has been validated on angiographic units from all manufacturers, though several software developers claimed vendor-independent transportability. Only one software allows for multiple procedures dose calculation. Conclusion Large differences among vendors made it clear that work remains to be done before an accurate and reliable skin dose mapping is available for all patients.

This investigation is aimed to study the feasibility of size-specific dose estimate (SSDE) to patient dosimetry in pediatric head CT scans and to establish typical values in a hospital in Tunja, Colombia. The volumetric computed tomography index (CTDIvol) and the dose-length product of 468 pediatric patients from newborn to 15-year-olds, who underwent non-contrast head CT scans, were collected retrospectively. For 186 cases only, SSDE was estimated using patient attenuated-based size metrics and CTDIvol,16-to-SSDE conversion factors reported in AAPM report 293. Results showed that SSDE is an accurate metric that can be used to establish typical dose values from pediatric head CT scans. Median SSDE values of 33.5, 31.6, 36.2 and 57.9 mGy were established as typical dose values for the 0–

Advantages of Cone Beam Computed Tomography (CBCT) include high-quality 3D imaging and reduced radiation exposure with relatively low cost. In this study, patient radiation exposure in CBCT implant planning dentistry was measured in terms of Kerma Area Product (KAP). Data were obtained from 217 CBCT scans on 168 individuals using a CS9300 Carestream system. Scans were made using 80–90 kVp, 4–5 mA, 8 and 13.3 s exposure time (depending on voxel size) and a fixed field of view (FOV) of 10 × 10 cm2 (medium). Mean KAP was estimated using two voxel sizes 180 × 180 × 180 μm3 and 200 × 200 × 200 μm3 and found to be 399 and 314 mGycm2, respectively. Corresponding KAP values found in literature ranged between 210 and 2140 mGycm2. Mean E was estimated using conversion coefficient factors found in literature, according to FOV size and tube voltage value and found to range between 24 and 161 μSv.

The European Directive 2013/59/Euratom focuses on the radiation protection and patientdosimetry. In particular, the dose absorbed by serial organs such as the spinal cord due to diagnosticexams plays a crucial role in the appraisal of medical exposure. In this work, a comparison betweendose measurements performed with GafchromicTM XR-QA2 and TLD 100H is presented. Thedosimeters&mdash, after a calibration procedure through an X-ray tube&mdash, were placed within the thoraxregion of an anthropomorphic phantom corresponding to the spinal cord area exposed to a thoracicCT procedure. The mean-dose value was measured with GafchromicTM first, and it was thencompared to the dose value obtained with TLDs, resulting in a good agreement between the twodosimetric methodologies. Additionally, the results showed that&mdash, due to the usage of the automaticexposure control (EC) system&mdash, the discrepancy between the two methods is proportional to thecurrent output of the CT system

Background Peptide receptor radionuclide therapy (PRRT) with [177Lu]-DOTA-TATE is an effective treatment of neuroendocrine tumors (NETs). After each cycle of treatment, patient dosimetry evaluates the radiation dose to the risk organs, kidneys, and bone marrow, the most radiosensitive tissues. Absorbed doses are calculated from the radioactivity in the blood and from single photon emission computed tomography (SPECT) images corrected by computed tomography (CT) acquired after each course of treatment. The aim of this work is to assess whether the dosimetry along all treatment cycles can be calculated using a single CT. We hypothesize that the absorbed doses to the risk organs calculated with a single CT will be accurate enough to correctly manage the patients, i.e., whether or not to continue PRRT. Twenty-four patients diagnosed with metastatic NETs undergoing PRRT with [177Lu]-DOTA-TATE were retrospectively included in this study. We compared radiation doses to the kidneys and bone marrow using two protocols. In the “classical” one, dosimetry is calculated based on a SPECT and a CT after each treatment cycle. In the new protocol, dosimetry is calculated based on a SPECT study after each cycle but with the first acquired CT for all cycles. Results The decision whether or not to stop PRRT because of unsafe absorbed dose to the risk organs would have been the same had the classical or the new protocol been used. The agreement between the cumulative doses to the kidneys and bone marrow obtained from the two protocols was excellent with Pearson’s correlation coefficients r = 0.95 and r = 0.99 (P

International audience; BACKGROUND: This study's aim was to develop our dosimetric methodology using a commercial workstation for the routine evaluation of the organs at risk during peptide receptor radionuclide therapy (PRRT) with 177Lu.METHODS: First, planar and SPECT sensitivity factors were determined on phantoms. The reconstruction parameters were optimized by SPECT/CT image acquisition using a NEMA IEC phantom containing a 500 ml bottle of 177Lu, to simulate a kidney. The recovery coefficients were determined on various phantoms. For the red marrow, this was calculated using a NEMA IEC phantom that contained a centrally placed bottle of 80 ml of 177Lu (to model the L2-L4 red marrow) flanked by two 200 ml bottles with 177Lu to simulate the kidneys. Then, SPECT/CT images were acquired at 4, 24, 72, and 192 h after injection in 12 patients with neuroendocrine tumors who underwent PRRT with 177Lu-DOTATATE. SPECT data were reconstructed using the iterative ordered subset expectation maximization (OSEM) method, with six iterations and ten subsets, attenuation, scatter, recovery resolution corrections, and a Gaussian post-filter of 0.11 cm. The liver, spleen, kidneys, and red marrow dose per administered activity (AD/A admin) values were calculated with the Medical Internal Radiation Dose (MIRD) formalism and the residence times (Dosimetry toolkit® application) using standard and CT imaging-based organ masses (OLINDA/EXM® V1.0 software).RESULTS: Sensitivity factors of 6.11 ± 0.01 and 5.67 ± 0.08 counts/s/MBq were obtained with planar and SPECT/CT acquisitions, respectively. A recovery coefficient of 0.78 was obtained for the modeled L2-L4 red marrow. The mean AD/A admin values were 0.43 ± 0.13 mGy/MBq [0.27-0.91] for kidneys, 0.54 ± 0.58 mGy/MBq [0.12-2.26] for liver, 0.61 ± 0.13 mGy/MBq [0.42-0.89] for spleen, and 0.04 ± 0.02 mGy/MBq [0.01-0.09] for red marrow. The AD/A admin values varied when calculated using the personalized and standard organ mass, particularly for kidneys (p = 1 × 10-7), spleen (p = 0.0069), and red marrow (p = 0.0027). Intra-patient differences were observed especially in organs close to or including tumor cells or metastases.CONCLUSIONS: The obtained AD/A admin values were in agreement with the literature data. This study shows the technical feasibility of patient dosimetry in clinical practice and the need to obtain patient-specific information.

One measurement and an algebraic formula are used to calculate the incident air kerma (Ka,i) at the skin after any CT examination, including cone-beam CT (CBCT) and multi-slice CT (MSCT). Empty scans were performed with X-ray CBCT systems (dental, C-arm and linac guidance scanners) as well as two MSCT scanners. The accumulated Ka,i at the flat panel (in CBCT) or the maximum incident air kerma at the isocentre (in MSCT) were measured using a solid-state probe. The average Ka,i(skin), at the skin of a hypothetical patient, was calculated using the proposed formula. Additional measurements of dose at the isocentre (DFOV) and kerma-area product (KAP), as well as Ka,i(skin) from thermoluminiscence dosimeters (TLDs) and size-specific dose estimates are presented for comparison. The Ka,i(skin) for the standard head size in the dental scanner, the C-arm (high dose head protocol) and the linac (head protocol) were respectively 3.33 ± 0.19 mGy, 15.15 ± 0.76 mGy and 3.23 ± 0.16 mGy. For the first MSCT, the calculated Ka,i(skin) was 13.1 ± 0.7 mGy and the TLDs provided a Ka,i(skin) between 10.3 ± 1.1 mGy and 13.8 ± 1.4 mGy. Estimation of patient air kerma in tomography with an uncertainty below 7% is thus feasible using an empty scan and conventional measurement tools. The provided equations and website can be applied to a standard size for the sake of quality control or to several sizes for the definition of diagnostic reference levels (DRLs). The obtained incident air kerma can be directly compared to the Ka,i from other X-ray modalities as recommended by ICRU and IAEA.

Introduction Digital mammography present many advantages in comparison to conventional mammography, such as high dynamic range and the post-processing of acquired images. One problem is that protocols may not be optimized, resulting in higher absorbed doses to patients. The objective of this work is to evaluate image quality and to estimate mean glandular doses (MGD) in patients submitted to mammography examinations with three digital systems and one screen-film system in Recife, Brazil. Methods To estimate the MGD, the parameters used to acquire images of 5475 patients, with ages between 40 and 64 years and compressed breasts between 2 and 9 cm, were registered. The MGD was calculated by multiplying the incident air kerma with conversion coefficients depending on the anode/filter, breast glandularity and half-value layer. The image quality evaluation of the digital systems was made using objective and subjective European criteria. Results The results showed MGDs in the range of 0.4-10.3 mGy and the higher values were observed with digital systems. It was also observed that in the digital systems the use of compression force is not adequate and the irradiation parameters are not optimized. The images failed to reproduce the pectoral muscle and the contrast-to-noise ratio was not adequate for one system, indicating the need to improve the patient’s positioning and the exposure parameters. Conclusion It can be concluded that the use of non-optimized irradiation parameters is causing the higher doses with digital systems, highlighting the insufficient compression force.

This study aimed to examine the relationship between fetal dose and the dose–length product, and to evaluate the impact of the number of rotations on the fetal doses and maternal effective doses using a 320‐row multidetector computed tomography unit in a wide‐volume mode. The radiation doses for the pregnant woman and the fetus were estimated using ImPACT CT Patient Dosimetry Calculator software for scan lengths ranging from 176 to 352 mm, using a 320‐row unit in a wide‐volume mode and an 80‐row unit in a helical scanning mode. In the 320‐row unit, the fetal doses in all scan lengths ranged from 3.51 to 6.52 mGy; the maternal effective doses in all scan lengths ranged from 1.05 to 2.35 mSv. In the 80‐row unit, the fetal doses in all scan lengths ranged from 2.50 to 3.30 mGy; the maternal effective doses in all scan lengths ranged from 0.83 to 1.68 mSv. The estimated conversion factors from the dose–length product (mGy・cm) to fetal doses (mGy) for the 320‐row unit in wide‐volume mode and the 80‐row unit in helical scanning mode were 0.06 and 0.05 (cm−1) respectively. While using a 320‐row MDCT unit in a wide‐volume mode, operators must take into account the number of rotations, the beam width as automatically determined by the scanner, the placement of overlap between volumetric sections, and the ratio of overlapping volumetric sections.

We modified the Imaging Performance Assessment of CT scanners (ImPACT) to evaluate the organ doses and the effective dose based on the International Commission on Radiological Protection (ICRP) Publication 110 reference male/female phantom with the Aquilion ONE ViSION Edition scanner. To select the new CT scanner, the measurement results of the CTDI100,c and CTDI100,p for the 160 (head) and the 320 (body) mm polymethylmethacrylate phantoms, respectively, were entered on the Excel worksheet. To compute the organ doses and effective dose of the ICRP reference male/female phantom, the conversion factors obtained by comparison between the organ doses of different types of phantom were applied. The organ doses and the effective dose were almost identical for the ICRP reference male/female and modified ImPACT. The results of this study showed that, with the dose assessment of the ImPACT, the difference in sex influences only testes and ovaries. Because the MIRD‐5 phantom represents a partially hermaphrodite adult, the phantom has the dimensions of the male reference man including testes, ovaries, and uterus but no female breasts, whereas the ICRP male/female phantom includes whole‐body male and female anatomies based on high‐resolution anatomical datasets. The conversion factors can be used to estimate the doses of a male and a female accurately, and efficient dose assessment can be performed with the modified ImPACT. PACS number: 87.53.LY, 87.57.Q‐, 87.57.‐s

The purpose of this study was to assess the level of patient radiation dose received in general fluoroscopy examinations, compare the findings with the international diagnostic reference levels (IDRLs), and establish the initial institutional (local) LDRLs. A comprehensive survey was conducted for general fluoroscopy examinations using the medical records of a Radiology Department of a leading regional hospital over a period close to one year. The cumulative reference point air kerma (Ka,r), kerma area product (KAP) and fluoroscopy time (FT) were recorded for six hundred and fifty (30% pediatric and 70% adult) patients undergoing routine fluoroscopy examinations using X‐ray equipment with built‐in integrated dose measuring system. Results which were obtained for adult general fluoroscopy indicated that 83% and 33% were below the IDRLs for KAP and fluoroscopy time, respectively. In children, 60% were found to be below the only available KAP diagnostic reference levels. Local diagnostic reference levels (LDRLs) have been proposed with respect to the missing DRLs for the Ka r, KAP, and fluoroscopy time. The majority of the examinations in the study were performed with longer fluoroscopy time, patient dose values per examination type were found to be broad and the mean values above the international diagnostic reference levels. This calls for proper and improved training and radiation protection skills for the responsible personnel, especially the equipment operators. PACS numbers: 87.53.Bn, 87.59.C‐, 87.59.cf, 87.53.Bn, 87.50.‐a, 87.53.‐j

Purpose The protocol for quality control of CBCT devices was produced as consensus among active MPEs of EFOMP, ESTRO and IAEA. It is available on-line since September 2017. In the beginning of 2018 we published an update including an appendix on patient dosimetry by EURADOS, comments by the German institute of standards (DIN) and remarks by users from countries that were not involved in the first edition, such as Austria, Costa Rica and Australia. This contribution gives a general overview of the guideline including insights about this recent update. Methods The guideline focuses on the measurement of objective image quality parameters and radiation output from any kind of CBCT device, including applications in dental radiology, C-arms and guidance systems in radiotherapy. Indications to use commercial or non-commercial phantoms and software are given, as well as to use ionization chambers or solid state dosemeters. The new EURADOS appendix includes an extensive review of patient dose data from recent research papers, organized by application and dose indicators: CTDI, DAP, effective dose, entrance surface dose, CTDIw, absorbed dose, D1-D2 and air kerma. The DIN has reviewed the details of the standards 6868–161 and 6868–15 for acceptance and constancy tests in dental CBCT. Individual comments have helped to clarify the measurements of radiation output and the methods to measure the modulation transfer function. Some colleagues have stressed the informative value of the appendices. Results The comments received were reviewed by the authors of the corresponding sections and discussed by the group in virtual meetings before being published as an update. The mentioned additions are meant to keep the document alive. They respond to questions raised by physicists that are starting to use the protocol inside and outside Europe. Conclusions The first presentation in the ECMP in Athens was followed by international presentations at ESTRO, ECR, IOMP and IRPA and national presentations in Italy, Spain, UK, Germany and other countries. Thanks to these voluntary efforts, physicists around the world are using and improving the document together. We also welcome your participation in this session and your feedback.

Radiation dose to organs of 100 adult patients undergoing lumbar spine (LS) radiography at a University Hospital have been assessed. Free in air kerma measurement using an ionization chamber was used for the patient dosimetry. Organ and effective dose to the patients were estimated using PCXMC (version 1.5) software. The organs that recorded significant dose due to LS radiography were lungs, stomach, liver, adrenals, kidney, pancreas, spleen, galbladder, and the heart. It was observed that the stomach recorded the highest dose (48.2 ± 1.2 μGy) for LS anteroposterior (AP). The spleen also recorded the highest dose (41.2 ± 0.5 μGy) for LS lateral (LAT). The mean entrance surface air kerma (ESAK) of LS LAT (122.2 μGy) was approximately twice that of LS AP (76.3 μGy), but the effective dose for both examinations were approximately the same (LS LAT = 8.6 μSv and LS AP = 10.4 μSv). The overall stochastic health effect of radiation to patients due to LS radiography in the University Hospital is independent of the projection of the examination (AP or LAT).

The aims of this study were to estimate the effective radiation doses from CT examinations of both adults and children in Japan and to study the impact of various scan parameters on the effective doses.A questionnaire, which contained detailed questions on the CT scan parameters employed, was distributed to 3000 facilities throughout Japan. For each scanner protocol, the effective doses for head (non-helical and helical), chest and upper abdomen acquisitions were estimated using ImPACT CT Patient Dosimetry Calculator software v. 1.0.4 (St George's Hospital, London, UK).The mean effective doses for chest and abdominal examinations using 80-110 kV were significantly lower than those using 120 kV. However, there was no statistically significant difference in the mean effective doses for head scans between facilities employing 80-110 kV and 120 kV. In chest and abdominal examinations, the mean effective doses using CT scanners from Western manufacturers [Siemens (Forchheim, Germany), Philips (Eindhoven, Netherlands) and GE Medical Systems (Milwaukee, WI)] were significantly lower than those of examinations using Japanese scanners [Hitachi (Kashiwa, Japan) and Toshiba (Otawara, Tochigi, Japan)], except for in paediatric chest examinations.The mean effective doses for adult head, chest and abdominal CT examinations were 2.9, 7.7 and 10.0 mSv, respectively, whereas the corresponding mean effective doses for paediatric examinations were 2.6, 7.1 and 7.7 mSv, respectively.Facilities using CT scanners by Western manufacturers commonly adopt low-tube-voltage techniques, and low-tube-voltage CT may be useful for reducing the radiation doses to the patients, particularly for the body region.

Clinical trials on 177 Lu 90 Y therapy used empirical activity ratios. Radionuclides (RN) with larger beta maximal range could favourably replace 90 Y. Our aim is to provide RN dose-deposition kernels and to compare the tumour control probability (TCP) of RN combinations. Dose kernels were derived by integration of the mono-energetic beta-ray dose distributions (computed using Monte Carlo) weighted by their respective beta spectrum. Nine homogeneous spherical tumours (125mm in diameter) and four spherical tumours including a lattice of cold, but alive, spheres (1, 3, 5, 7mm in diameter) were modelled. The TCP for 93 Y, 90 Y and 125 Sn in combination with 177 Lu in variable proportions (that kept constant the renal cortex biological effective dose) were derived by 3D dose kernel convolution. For a mean tumour-absorbed dose of 180 Gy, 2mm homogeneous tumours and tumours including 3mm diameter cold alive spheres were both well controlled (TCP > 0.9) using a 7525% combination of 177 Lu and 90 Y activity. However, 125 Sn 177 Lu achieved a significantly better result by controlling 1mm-homogeneous tumour simultaneously with tumours including 5mm diameter cold alive spheres. Clinical trials using RN combinations should use RN proportions tuned to the patient dosimetry. 125 Sn production and its coupling to somatostatin analogue appear feasible. Assuming similar pharmacokinetics 125 Sn is the best RN for combination with 177 Lu in peptide receptor radiotherapy justifying pharmacokinetics studies in rodent of 125 Sn-labelled somatostatin analogues. © 2012 Institute of Physics and Engineering in Medicine.

This work investigates the validity of estimating effective dose for cone beam CT (CBCT) exposures from the weighted CT dose index (CTDIW) and irradiated length.Measurements were made within cylindrical poly(methyl methacrylate) (PMMA) phantoms measuring 14 cm and 28 cm in length and 32 cm in diameter for the 200° DynaCT acquisition on the Siemens Artis zee fluoroscopy unit (Siemens Medical Solutions, Erlangen, Germany). An interpolated average dose was calculated to account for the partial rotation. Organ and effective doses were estimated by modelling projections in the Monte Carlo software programme PCXMC (STUK, Helsinki, Finland).The CTDIW was found to closely approximate the interpolated average dose if the positions of the measured doses reflected the X-ray beam rotation. The average dose was found to increase by 8% when the phantom length was increased from 14 to 28 cm. Using the interpolated average dose and the irradiated length for effective dose calculations gave similar values to PCXMC when a double-length (28-cm) CT dose index phantom was irradiated. Simplifying the estimation of effective dose with PCXMC by modelling just 4 projections around the abdomen gave effective doses that were only 7% different to those given when 41 projections were modelled. Calculated doses to key organs within the beam varied by as much as 27%.Estimating effective dose from the CTDIW and the irradiated length is sufficiently accurate for CBCT if the chamber positions are considered carefully. A conversion factor can be used only if a single CT dose index phantom is available. The estimation of organ doses requires a large number of modelled projections in PCXMC.

Introduction Recently developed portable dental X-ray units increase the mobility of the forensic odontologists and allow more efficient X-ray work in a disaster field, especially when used in combination with digital sensors. This type of machines might also have potential for application in remote areas, military and humanitarian missions, dental care of patients with mobility limitation, as well as imaging in operating rooms. Objective To evaluate radiographic image quality acquired by three portable X-ray devices in combination with four image receptors and to evaluate their medical physics parameters. Materials and methods Images of five samples consisting of four teeth and one formalin-fixed mandible were acquired by one conventional wall-mounted X-ray unit, MinRay® 60/70 kVp, used as a clinical standard, and three portable dental X-ray devices: AnyRay® 60 kVp, Nomad® 60 kVp and Rextar® 70 kVp, in combination with a phosphor image plate (PSP), a CCD, or a CMOS sensor. Three observers evaluated images for standard image quality besides forensic diagnostic quality on a 4-point rating scale. Furthermore, all machines underwent tests for occupational as well as patient dosimetry. Results Statistical analysis showed good quality imaging for all system, with the combination of Nomad® and PSP yielding the best score. A significant difference in image quality between the combination of the four X-ray devices and four sensors was established (p For patient safety, the exposure rate was determined and exit dose rates for MinRay® at 60 kVp, MinRay® at 70 kVp, AnyRay®, Nomad® and Rextar® were 3.4 mGy/s, 4.5 mGy/s, 13.5 mGy/s, 3.8 mGy/s and 2.6 mGy/s respectively. The kVp of the AnyRay® system was the most stable, with a ripple of 3.7%. Short-term variations in the tube output of all the devices were less than 10%. AnyRay® presented higher estimated effective dose than other machines. Occupational dosimetry showed doses at the operator's hand being lowest with protective shielding (Nomad®: 0.1 μGy). It was also low while using remote control (distance > 1 m: Rextar® Conclusions The present study demonstrated the feasibility of three portable X-ray systems to be used for specific indications, based on acceptable image quality and sufficient accuracy of the machines and following the standard guidelines for radiation hygiene.

Purpose Cone beam CT (CBCT) is an advanced imaging technique compared to panoramic radiography and of lower cost than a conventional CT procedure. Its advantages are the focused imaging of the maxillofacial region and a reduced radiation exposure with relatively low cost. CBCT produces three-dimensional information on the facial skeleton and teeth in a few seconds time. The purpose of the study was to measure patient radiation exposure in terms of Kerma Area Product (KAP) in implant planning dentistry, to estimate effective dose (Ef) and to compare patient radiation doses with corresponding values from CT and conventional panoramic radiography, in clinical practice. Methods The X-ray system used was a CS9300 Carestream system. Patient sample included 168 individuals undergoing 211 CBCT examinations. Data recorded included: KAP, tube voltage, tube current, exposure time, field of view (FOV), patient age and clinical indication. Five examination types were selected in order to keep protocol settings as similar as possible. Results Patient mean age was 55 years. Patients underwent either 1 (80.2%), 2 (14.7%), 3 (2.5%) or >3 (2.3%) CBCT examinations. Protocol details were: 80–90 kV, 4–5 mA, 8 s exposure time and fixed FOV of 10*10 cm2. Mean (SD) KAP was 533 (112) mGy*cm2. Median KAP value was 530 mGy*cm2. A conversion factor of 0.08 mSv/Gycm2 was used to calculate Ef. Mean (SD) Ef was found 42.7 (9.0) μSv (median 42.4 μSv). A broad comparison was done with international data from dental dosimetry studies using different modalities, showing that CBCT requires 4–10 times lower radiation exposure than corresponding CT images, depending on examination type. At the same time, CBCT patient radiation exposure is 3–6 times higher than panoramic radiography. Conclusions CBCT is an accurate and useful tool for many clinical oral-maxillofacial indications. Although CBCT doses are significantly lower than conventional CT, yet they are higher than those from conventional imaging used in dentistry. Therefore, a risk/benefit analysis must be carried out before a CBCT investigation is requested.

Biological effects induced by exposure to radiation made evident the need for an accurate dosimetry from the early days of X-ray use in medicine. Later the scientific interest turned also to the estimation of risks of radiation-induced cancer and genetic effects. Various dosimetric quantities have been used in diagnostic radiology and sometimes confusion is caused because the same name is used for different quantities. The question arises: what is patient dose and what is not? It’s common practice to indicate the dose received by a patient in radiology using the dosimetric indexes defined for the different imaging modalities. However, dosimetric indexes are a useful tool for practices optimization and comparison, but certainly they don’t describe patient dose. To accurately estimate patient dose there is the need to collect a lot of information concerning patient characteristics and irradiation events in order to obtain organ or tissue dose. Nowadays, thanks to the digital technology used in medical imaging, various ways of collecting these data are available. The information is communicated using specific standards (i.e. DICOM), such as the non-image information object definitions. These objects are carrying information about equipment output and other dose related information which allow the user to provide a more accurate estimate of patient dose. The standards are in continuous development, to provide more and more detailed information and to include most recent modalities (e.g. CBCT). This talk will review the basic concepts on patient dosimetry as well as the existing DICOM objects and IHE profiles used to monitor patient exposure, highlighting pros and cons and introducing to the future developments.

During the last decade, there has been an explosion of new radiation therapy planning and delivery tools. We went through a rapid transition from conventional three-dimensional (3D) conformal radiation therapy to intensity-modulated radiation therapy (IMRT) treatments, and additional new techniques for motion-adaptive radiation therapy are being introduced. These advances push the frontiers in our effort to provide better patient care; and with the addition of IMRT, temporal dimensions are major challenges for the radiotherapy patient dosimetry and delivery verification. Advanced techniques are less tolerant to poor implementation than are standard techniques. Mis-administrations are more difficult to detect and can possibly lead to poor outcomes for some patients. Instead of presenting a manual on quality assurance for radiation therapy, this manuscript provides an overview of dosimetry verification tools and a focused discussion on breath holding, respiratory gating and the applications of four-dimensional computed tomography in motion management. Some of the major challenges in the above areas are discussed.

Interventional cardiology procedures result in substantial patient radiation doses due to prolonged fluoroscopy time and radiographic exposure. The procedures that are most frequently performed are coronary angiography, percutaneous coronary interventions, diagnostic electrophysiology studies and radiofrequency catheter ablation. Patient radiation dose in these procedures can be assessed either by measurements on a series of patients in real clinical practice or measurements using patient-equivalent phantoms. In this article we review the derived doses at non-pediatric patients from 72 relevant studies published during the last 22 years in international scientific literature. Published results indicate that patient radiation doses vary widely among the different interventional cardiology procedures but also among equivalent studies. Discrepancies of the derived results are patient-, procedure-, physician-, and fluoroscopic equipmentrelated. Nevertheless, interventional cardiology procedures can subject patients to considerable radiation doses. Efforts to minimize patient exposure should always be undertaken.

OBJETIVO: Os objetivos deste trabalho são: a) avaliar os procedimentos radiográficos e estimar o valor do kerma no ar na superfície de entrada nos recém-nascidos prematuros submetidos a exames de tórax e abdome, realizados no setor de neonatologia de um hospital público de Belo Horizonte; b) estimar as doses nos órgãos e os respectivos riscos de ocorrência de câncer nesses órgãos em decorrência das exposições à radiação. MATERIAIS E MÉTODOS: Foram analisados os prontuários dos pacientes internados no setor de neonatologia desse hospital durante o período de maio a setembro de 2004, anotando-se os dados antropométricos, data de internação/alta, exames de raios X realizados. O kerma no ar na superfície de entrada foi determinado a partir do rendimento do tubo de raios X e dos parâmetros de irradiação utilizados nos exames. As doses nos órgãos foram estimadas com o software PCXMC e o risco, durante o restante da expectativa de vida, com o software IREP. RESULTADOS: O valor médio do kerma no ar na superfície de entrada por exame foi abaixo do nível de referência da publicação da Comunidade Européia. Para o paciente mais severamente irradiado, os órgãos mais suscetíveis à ocorrência de câncer foram fígado, mama e estômago, com valores máximos de excess relative risk, respectivamente, de 3,4%, 2,3% e 1,7%. CONCLUSÃO: Foi constatada a necessidade de otimização dos procedimentos radiográficos com vista à diminuição do risco para os recém-nascidos, que apesar de ser considerado baixo (comparativamente ao benefício), deve ser sempre diminuído para valores tão baixos quanto razoavelmente exeqüíveis.OBJECTIVE: The present study was aimed at: a) evaluating radiographic procedures and estimating entrance surface air kerma in preterm neonates submitted to chest and abdominal radiography at the unit of neonatology in a public hospital of Belo Horizonte, MG, Brazil; b) estimating the dose to organs and respective risks for cancer as a result from radiation exposure. MATERIALS AND METHODS: Records of patients admitted to the unit of neonatology of this hospital in the period between May and September 2004 were reviewed. Anthropometric data, admission/discharge dates and radiographic studies performed were recorded for each of the patients. The calculation of the entrance surface air kerma was based on the x-ray tube output and irradiation parameters adopted for examinations. Dose to organs was calculated with the aid of the software PCXMC, and the lifetime risk for cancer, with the software IREP. RESULTS: Mean entrance surface air kerma per examination was below the diagnostic reference levels recommended by the European Community. In the most severely irradiated patients, liver, breast and stomach were the organs at highest risk for cancer, with maximum excess relative risk of respectively 3.4%, 2.3%, and 1.7%. CONCLUSION: The present study demonstrated the need for optimization of radiographic procedures in order to reduce the risks for neonates that, in spite of being considered to be low as compared with the benefits, should be reduced to values as low as reasonably achievable.

OBJETIVO: Os objetivos deste trabalho são: a) avaliar os procedimentos radiográficos e estimar o valor do kerma no ar na superfície de entrada nos recém-nascidos prematuros submetidos a exames de tórax e abdome, realizados no setor de neonatologia de um hospital público de Belo Horizonte; b) estimar as doses nos órgãos e os respectivos riscos de ocorrência de câncer nesses órgãos em decorrência das exposições à radiação. MATERIAIS E MÉTODOS: Foram analisados os prontuários dos pacientes internados no setor de neonatologia desse hospital durante o período de maio a setembro de 2004, anotando-se os dados antropométricos, data de internação/alta, exames de raios X realizados. O kerma no ar na superfície de entrada foi determinado a partir do rendimento do tubo de raios X e dos parâmetros de irradiação utilizados nos exames. As doses nos órgãos foram estimadas com o software PCXMC e o risco, durante o restante da expectativa de vida, com o software IREP. RESULTADOS: O valor médio do kerma no ar na superfície de entrada por exame foi abaixo do nível de referência da publicação da Comunidade Européia. Para o paciente mais severamente irradiado, os órgãos mais suscetíveis à ocorrência de câncer foram fígado, mama e estômago, com valores máximos de excess relative risk, respectivamente, de 3,4%, 2,3% e 1,7%. CONCLUSÃO: Foi constatada a necessidade de otimização dos procedimentos radiográficos com vista à diminuição do risco para os recém-nascidos, que apesar de ser considerado baixo (comparativamente ao benefício), deve ser sempre diminuído para valores tão baixos quanto razoavelmente exeqüíveis. OBJECTIVE: The present study was aimed at: a) evaluating radiographic procedures and estimating entrance surface air kerma in preterm neonates submitted to chest and abdominal radiography at the unit of neonatology in a public hospital of Belo Horizonte, MG, Brazil; b) estimating the dose to organs and respective risks for cancer as a result from radiation exposure. MATERIALS AND METHODS: Records of patients admitted to the unit of neonatology of this hospital in the period between May and September 2004 were reviewed. Anthropometric data, admission/discharge dates and radiographic studies performed were recorded for each of the patients. The calculation of the entrance surface air kerma was based on the x-ray tube output and irradiation parameters adopted for examinations. Dose to organs was calculated with the aid of the software PCXMC, and the lifetime risk for cancer, with the software IREP. RESULTS: Mean entrance surface air kerma per examination was below the diagnostic reference levels recommended by the European Community. In the most severely irradiated patients, liver, breast and stomach were the organs at highest risk for cancer, with maximum excess relative risk of respectively 3.4%, 2.3%, and 1.7%. CONCLUSION: The present study demonstrated the need for optimization of radiographic procedures in order to reduce the risks for neonates that, in spite of being considered to be low as compared with the benefits, should be reduced to values as low as reasonably achievable.

Although (18)F-labeled NaF was the first widely used agent for skeletal scintigraphy, it quickly fell into disuse after the introduction of (99m)Tc-labeled bone-imaging agents. Recent comparative studies have demonstrated that (18)F-fluoride PET is more accurate than (99m)Tc-diphosphonate SPECT for identifying both malignant and benign lesions of the skeleton. Combining (18)F-fluoride PET with other imaging, such as CT, can improve the specificity and overall accuracy of skeletal (18)F-fluoride PET and probably will become the routine clinical practice for (18)F-fluoride PET. Although (18)F-labeled NaF and (99m)Tc-diphosphonate have a similar patient dosimetry, (18)F-fluoride PET offers shorter study times (typically less than 1 h), resulting in a more efficient workflow, improved patient convenience, and faster turnarounds of reports to the referring physicians. With the widespread availability of PET scanners and the improved logistics for the delivery of (18)F radiopharmaceuticals, prior limitations to the routine use of (18)F-fluoride bone imaging have largely been overcome. The favorable imaging performance and the clinical utility of (18)F-fluoride PET, compared with (99m)Tc-diphosphonate scintigraphy, support the reconsideration of (18)F-fluoride as a routine bone-imaging agent.

The optically stimulated luminescence (OSL-BeO) dosemeter is increasingly being used as a dosimetric technique in various fields such as medical dosimetry. According to our fixed dose protocol, the activities of 3.7-7.4 GBq I-131 source is used for thyroid carcinoma therapy. The in house calibration process for usage of OSL’s at hospital was arranged according to the encapsulated I-131. The measurement point was planned in three different radial distances from source free in air. The dose-rate measurement was done by Geiger-Muller (GM), and then three pieces of OSL was placed in the same positions for one hour. The inverse square law consistency was found (R2=0.99). The calibration coefficient was calculated. For determining the performance of OSL at different dose rates, it used for personnel and patient dosimetry. The average annual dose/2mon to the whole body for all staff by OSL were 0.80 mSv. After administration of 3.7 GBq (100 mCi) therapeutic dose to selected patients, the average pectoral dose was 97.5+32.6 mSv. This calibration process is helpful for confidence of OSL detectors used for dosimetry of staff and patients treated with high activity I-131.

The objective of this work is to assess patient organ doses, effective doses and entrance surface doses in conventional diagnostic radiology procedures for standard adult patient. The survey consists of measurements of doses delivered to 239 patients in nine types of X-ray examinations. Three types of data were collected: X-ray machine data, patient data, and output measurements. Entrance surface dose was assessed based on the survey data and subsequently, using conversion coefficients, the organ doses and effective doses were calculated. Values of the entrance surface dose and the effective dose were estimated to be 0.4 to 5.8 mGy and 0.03 to 3.00 mSv for different examinations. Derived doses were compared with recommended general diagnostic reference levels. The impact of examination parameters on dose values was discussed. Except for posterior-anterior chest examination, all estimated doses are lower than stated reference levels. Survey data are aimed at helping development of national quality control and radiation protection programmed for medical exposures.

To establish a system for patient dosimetry audit and setting of local diagnostic reference levels (LDRLs) for nuclear medicine (NM) CT.Computed radiological information system (CRIS) data were matched with NM paper records, which provided the body region and dose mode for NMCT carried out at a large UK hospital. It was necessary to divide data in terms of the NM examination type, body region and dose mode. The mean and standard deviation dose-length products (DLPs) for common NMCT examinations were then calculated and compared with the proposed National Diagnostic Reference Levels (NDRLs). Only procedures which have 10 or more patients will be used to suggest LDRLs.For most examinations, the mean DLPs do not exceed the proposed NDRLs. The bone single-photon emission CT/CT lumbar spine data clearly show the need to divide data according to the purpose of the scan (dose mode), with mean (±standard error) DLPs ranging from 51 ± 5 mGy cm (low dose) to 1086 ± 124 mGy cm (metal dose).A system for NMCT patient dose audit has been developed, but there are non-trivial challenges which make the process labour intensive. These include limited information provided by CRIS downloads, dependence on paper records and limited number of examinations available owing to the need to subdivide data. Advances in knowledge: This article demonstrates that a system can be developed for NMCT patient dose audit, but also highlights the challenges associated with such audit, which may not be encountered with more routine audit of radiology CT.

In recent years, dose justification and optimization have been attempted in percutaneous coronary intervention (PCI); however, deterministic effects have been reported. To prevent radiation skin injuries in PCI, it is necessary to measure the patient entrance skin dose (ESD), but an accurate dose measurement method has not yet been established. In this study, we developed a dosimetry gown that can measure the ESD during PCI using multiple radiophotoluminescence dosimeters (RPLDs). The RPLDs were placed into 84 pockets that were sewn into a dosimetry gown. Patients wear the original dosimetry gown during the procedures, after which we obtain accurate ESD measurements. We believe that this method using RPLDs and a newly-designed dosimetry gown provides accurate ESD measurements during PCI. We expect this system to become a standard method for measuring ESD during PCI.

The increasing prevalence and complexity of fluoroscopically guided interventions (FGI) raises concern regarding radiation dose to patients subjected to the procedure. Despite current evidence showing the risk to patients from the deterministic effects of radiation (e.g. skin burns), radiation induced injuries remain commonplace. This review aims to increase the awareness surrounding radiation dose measurement for patients undergoing FGI. A review of the literature was conducted alongside previous researches from the authors' department. Studies pertaining to patient dose measurement, its formalism along with current advances and present challenges were reviewed. Current patient monitoring techniques (using available radiation dosimeters), as well as the inadequacy of accepting displayed dose as patient radiation dose is discussed. Furthermore, advances in real-time patient radiation dose estimation during FGI are considered. Patient dosimetry in FGI, particularly in real time, remains an ongoing challenge. The increasing occurrence and sophistication of these procedures calls for further advances in the field of patient radiation dose monitoring. Improved measuring techniques will aid clinicians in better predicting and managing radiation induced injury following FGI, thus improving patient care.

The impact of digitalization on the average glandular doses in 49 mammographic units participating in the Flemish Breast Cancer Screening Program was studied. Screen-film was changed to direct digital radiography and computed radiography in 25 and 24 departments respectively. Average glandular doses were calculated before and after digitalization for different PMMA-phantom thicknesses and for groups of 50 successive patients. For the transition from screen-film to computed radiography both phantom and patient dose data show a significant increase of dose with digitalization. For the transition from screen-film to direct digital radiography the evolution of the average glandular dose depends on the phantom thickness. For 20mm PMMA a significant increase in dose was found, for 45mm and 70mm PMMA there was a significant decrease in dose. The median average glandular dose of the patient dosimetry showed a smaller but significant decrease.

The Brazilian legislation has only established diagnostic reference levels (DRLs) in terms of Multiple Scan Average Dose (MSAD) as a quality control parameter for computed tomography (CT) scanners. Compliance with DRLs can be verified by measuring the Computed Tomography Kerma Index (Ca,100) with a pencil ionization chamber or by obtaining the kerma distribution in CT scans with radiochromic films or rod shape lithium fluoride termoluminescent dosimeters (TLD-100). TL dosimeters were used to record kerma profiles and to determine MSAD values of a Bright Speed model GE CT scanner. Measurements were done with radiochromic films and TL dosimeters distributed in cylinders positioned in the center and in four peripheral bores of a standard polymethylmethacrylate (PMMA) body CT dosimetry phantom. Irradiations were done using a protocol for adult chest. The maximum values were found at the midpoint of the longitudinal axis. The MSAD values obtained with three dosimetric techniques were compared., {"references":["IAEA - International Atomic Energy Agency, Dosimetry in diagnostic\nradiology: an international code of practice. TRS Serie 457, Vienna,\n2007.","Brazil, Radiological Protection Directives for Medical and Dental\nRadiodiagnostic. Portaria 453, Brasilia, DF, 1998 [in Portuguese].","IAEA - International Atomic Energy Agency, International basic safety\nstandards for protection against ionizing radiation and for safety of\nradiation sources. Safety Series, 115, Vienna, 1996.","O. Rampado, E. Garelli, R. Ropolo, \"Computed tomography dose\nmeasurements with radiochromic films and a flatbed scanner,\" Med.\nPhys., vol. 37, no. 1, Jan 2010, pp. 189-196.","NIST - National Institute of Standards and Technology, At\nhttp://www.nist.gov/pml/data/xraycoef/index.cfm. - Access 15 Sept.\n2010.","EC - European Commission, European guidelines on quality criteria for\ncomputed tomography. EUR 16262 EN, Luxembourg, 1997.","ISO - International Standardization Organization, ISO 12794-1:\nThermoluminescent dosimeters for extremities and eyes. Geneva, 1997."]}

Patient dosimetry studies in diagnostic radiology in Nigeria have been on measurement of entrance skin dose and effective dose. Another important and easy to measure radiation dose descriptor that could be used to assess patient dose in radiological procedures is dose area product (DAP). Knowledge of DAP with location and projection of X‐ray beam allows direct calculation of organ dose and effective dose. In this study, DAP for commonly performed radiological examinations (abdomen, chest, lumbo sacral joint, pelvis, paranasal sinus, and skull) in four diagnostic centers in Nigeria were determined. These centers comprise of three classes of health care center namely tertiary, private, and specialist hospitals. Mathematical method was used to determine DAP received by 336 patients undergoing radiological examinations at the selected diagnostic centers. The DAP received by patient from each radiological examination varies from center to center. The range factor (RF) of DAP for individual patients ranged from 1.55–4.56, while RF of DAP among the selected centers was 2.27–55.84. The highest RF of DAP (55.84) was obtained from X‐ray examination of the chest. This variation was due to the application of anti‐scatter grid, and high kVp and high mAs values for chest examination by only one of the centers. The very wide variation in DAP found among diagnostic centers in this survey showed that there is need to harmonize radiological techniques of common X‐ray examination among different diagnostic centers. This would ensure optimal protection of patient against excessive radiation dose. PACS numbers: 87.53.Bn; 87.59.B

Entrance surface dose from two diagnostic x-ray centers in Nigeria for three common radiological examinations is presented in this study. Entrance surface doses for 294 patients drawn from Niger state hospital Minna and Two-Tees x-ray centre, Ibadan are included in this dose survey. The air kerma for each patient was measured using thermoluminescent dosimeter chips (TLD-100). The air kerma for each patient was then multiplied by a back scatter factor of 1.35 to obtain the Entrance surface dose. Generally doses obtained in this study were found to be higher than those in published works and International Atomic Energy Agency recommended limits for chest examination. The range factor at Niger State General Hospital was as high as 12 in some cases but as low as 1 in most cases at Two-Tees X-ray center. The doses obtained for skull and abdomen examination were found to be within acceptable International Atomic Energy Agency recommended limit.

Aim : To study dosimetry of patients during the external radiotherapy of head and neck cancers from different hospitals of the northeastern region (NER) of India. Materials and Methods : 35 confirmed cases of head and neck cancers reporting to three different hospitals in the NER of India who underwent radiation treatment were the materials for the study. Dosimetry was carried out at 8(eight) anatomical points to these patients, namely, target (entrance and exit points), forehead, chest, abdomen, gonad, arm, and leg respectively by thermoluminescence (TL) as well as optically stimulated luminescence (OSL) dosimeters. Unlike conventional appliances, we used common iodized salt as TL/OSL phosphor. Results : Patient dosimetry was found to vary with an average of 1.17 ± 0.39 Sv at forehead, 1.24 ± 0.39 Sv at chest, 0.52 ± 0.13 Sv at gonad to a minimum of 0.26 ± 0.07 Sv at leg areas when exposed to a cumulative dose of 65 Sv at the target. Conclusion : Maximum dose received from a stray radiation is about 1.5 Sv at forehead/chest and dosimetry of patient among the three centers is not significantly different at the 5% level of probability.

The objective of this study were to obtain dosimetric data from a patient with thyroid cancer simultaneously undergoing peritoneal dialysis therapy, so as to determine the appropriate amount of 131I activity to be applied therapeutically. Percentages of radioiodine in the blood and the whole-body were evaluated, and radiation absorbed doses were calculated according to OLINDA/EXM software. Whole-body 131I effective half-time was 45.5 hours, being four times longer than for patients without any renal dysfunction. Bone-marrow absorbed dose was 0.074 mGy/MBq, with ablative procedure maintenance at 3.7 GBq, as the reported absorbed dose was insufficiently restrictive to change the usual amount of radioiodine activity administered for ablation. It was concluded that radioiodine therapeutic-dose adjustment, based on individual patient dosimetry, is an important way of controlling therapy. It also permits the safe and potential delivery of higher doses of radiation to tumors and undesirable tissues, with a minimum of malignant effects on healthy tissues.