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Pregabalin (PGB) is widely used clinically; however, its pharmacokinetics (PK) has not been studied in pediatric patients with renal impairment (RI). To design optimized PGB regimens for pediatric patients with varying degrees of RI and predict exposure to PGB, physiologically based pharmacokinetic (PBPK) models of PGB were developed and verified, and its disposition was simulated in the healthy population and adults with RI. The simulated results from the PBPK models after single-dose and multi-dose administrations of PGB were consistent with the corresponding observed data based on the fold error values of less than 2. The area under curve ratios were 1.23 ± 0.06, 2.02 ± 0.10, 3.86 ± 0.21, and 9.92 ± 0.79 in pediatric patients with mild, moderate, severe, and end-stage RI, respectively. Based on the predictions for pediatric patients with moderate, severe, and end-stage RI, the maximum dose should not exceed 7, 3.5, and 1.4 mg/kg/day, respectively, among those weighing 30 kg. In conclusion, the developed PBPK model is a valuable tool for predicting PGB dosage for pediatric patients with RI.

Background There are 2 approaches to intensifying antihypertensive treatment when target blood pressure is not reached, adding a new medication and maximizing dose. Which strategy is better is unknown. Objective To assess the frequency of intensification by adding a new medication versus maximizing dose, as well as the association of each method with intensification sustainability and follow-up systolic blood pressure (SBP). Design Large-scale, population-based, retrospective cohort study. Observational data were used to emulate a target trial with 2 groups, new medication and maximizing dose, who underwent intensification of their drug regimen. Setting Veterans Health Administration (2011 to 2013). Patients Veterans aged 65 years or older with hypertension, an SBP of 130 mm Hg or higher, and at least 1 antihypertensive medication at less than the maximum dose. Measurements The following 2 intensification approaches were emulated: adding a new medication, defined as a total dose increase with new medication, and maximizing dose, defined as a total dose increase without new medication. Inverse probability weighting was used to assess the observational effectiveness of the intensification approach on sustainability of intensified treatment and follow-up SBP at 3 and 12 months. Results Among 178 562 patients, 45 575 (25.5%) had intensification by adding a new medication and 132 987 (74.5%) by maximizing dose. Compared with maximizing dose, adding a new medication was associated with less intensification sustainability (average treatment effect, -15.2% [95% CI, -15.7% to -14.6%] at 3 months and -15.1% [CI, -15.6% to -14.5%] at 12 months) but a slightly larger reduction in mean SBP (-0.8 mm Hg [CI, -1.2 to -0.4 mm Hg] at 3 months and -1.1 mm Hg [CI, -1.6 to -0.6 mm Hg] at 12 months). Limitation Observational data; largely male population. Conclusion Adding a new antihypertensive medication was less frequent and was associated with less intensification sustainability but slightly larger reductions in SBP. Trials would provide the most definitive support for our findings. Primary funding source National Institute on Aging and Veterans Health Administration.

As NPPs continue to operate, liquid waste continues to be generated, and containers are needed to store and transport them at low cost and high capacity. To transport and store liquid phase very low-level radioactive waste (VLLW), a container is designed by considering related regulations. The design was constructed based on the existing container design, which easily transports and stores liquid waste. The radiation shielding calculation was performed according to the composition change of barium sulfate (BaSO4) using the Monte Carlo N-Particle (MCNP) code. High-density polyethylene (HDPE) without mixing the additional BaSO4, represented the maximum dose of 1.03 mSv/hr (

This paper quantifies the inhalation and ingestion doses to different organs and tissues due to radon dissolved in drinking water. For this a study was under taken in Ludhiana district of Punjab, India. Radon enters the human body through respiratory tract during inhalation and through stomach during ingestion process. Utilizing the measured radon concentrations in water samples and adopting dose conversion models, ingestion doses corresponding to different age groups (infants, 1-year, 5-year, 10-year, 15-year and adults) were estimated. The study concludes that the maximum dose is received by the stomach as compared to other organs and tissues. Dose to lower age groups was found to be higher than that for the adults. Cancer mortality and morbidity risks have also been estimated for different cancer-sites. Stomach was seen to possess maximum cancer mortality risk for both male and female gender. An assessment of contribution of radon dissolved in water radon to indoor concentration was also made.

PURPOSE To derive the isodose line R relative to the prescription dose below which irradiated normal tissue (NT) regions benefit from a hypofractionated schedule with an isoeffective dose to the tumor. To apply the formalism to clinical case examples. METHODS From the standard biologically effective dose (BED) equation based on the linear-quadratic (LQ) model, the BED of an NT that receives a relative proportion r of the prescribed dose per fraction for a given α/β-ratio of the tumor, (α/β)T , and NT, (α/β)NT , is derived for different treatment schedules while keeping the BED to the tumor constant. Based on this, the "break-even" isodose line R is then derived. The BED of NT regions that receive doses below R decreases for more hypofractionated treatment schedules, and hence a lower risk for NT injury is predicted in these regions. To assess the impact of a linear behavior of BED for high doses per fraction (>6 Gy), we evaluated BED also using the LQ-linear (LQ-L) model. RESULTS The formalism provides the equations to derive the BED of an NT as function of dose per fraction for an isoeffective dose to the tumor and the corresponding break-even isodose line R. For generic α/β-ratios of (α/β)T = 10 Gy and (α/β)NT = 3 Gy and homogeneous dose in the target, R is 30%. R is doubling for stereotactic treatments for which tumor control correlates with the maximum dose of 100% instead of the encompassing isodose line of 50%. When using the LQ-L model, the notion of a break-even dose level R remains valid up to about 20 Gy per fraction for generic α/β-ratios and DT=2(α/β) . CONCLUSIONS The formalism may be used to estimate below which relative isodose line R there will be a differential sparing of NT when increasing hypofractionation. More generally, it allows to assess changes of the therapeutic index for sets of isoeffective treatment schedules at different relative dose levels compared to a reference schedule in a compact manner.

Regulatory toxicology seeks to ensure that exposures to chemicals encountered in the environment, in the workplace, or in products pose no significant hazards and produce no harm to humans or other organisms, i.e., that chemicals are used safely. The most practical and direct means of ensuring that hazards and harms are avoided is to identify the doses and conditions under which chemical toxicity does not occur so that chemical concentrations and exposures can be appropriately limited. Modern advancements in pharmacology and toxicology have revealed that the rates and mechanisms by which organisms absorb, distribute, metabolize and eliminate chemicals—i.e., the field of kinetics—often determine the doses and conditions under which hazard, and harm, are absent, i.e., the safe dose range. Since kinetics, like chemical hazard and toxicity, are extensive properties that depend on the amount of the chemical encountered, it is possible to identify the maximum dose under which organisms can efficiently metabolize and eliminate the chemicals to which they are exposed, a dose that has been referred to as the kinetic maximum dose, or KMD. This review explains the rationale that compels regulatory toxicology to embrace the advancements made possible by kinetics, why understanding the kinetic relationship between the blood level produced and the administered dose of a chemical is essential for identifying the safe dose range, and why dose-setting in regulatory toxicology studies should be informed by estimates of the KMD rather than rely on the flawed concept of maximum-tolerated toxic dose, or MTD.

In this study, we aim to clarify the dosimetric characteristics of a real time variable shape rubber containing tungsten (STR) as a thin bolus in 6-MV photon radiotherapy. The percentage depth doses (PDDs) and lateral dose profiles (irradiation field = 10 × 10 cm2) in the water-equivalent phantom were measured and compared between no bolus, a commercial 5-mm gel bolus, and 0.5-, 1-, 2-, and 3-mm STR boluses. The characteristics of the PDDs were evaluated according to relative doses at 1 mm depth (D1mm) and depth of maximum dose (dmax). To determine the distance of the shift caused by the STR bolus, the PDD value at a depth of 100 mm without a bolus was obtained. For each STR thickness, the difference between the depth corresponding to this PDD value and 100 mm was calculated. The penumbra size and width of the 50% dose were evaluated using lateral dose profiles. The D1mm with no bolus, 5-mm gel bolus, and 0.5-, 1-, 2-, and 3-mm STR boluses were 47.6%, 91.5%, 78.2%, 86.6%, 89.3%, and 89.4%, respectively, and the respective dmax values were 15, 10, 13, 12, 11, and 10 mm. The shifting distance of the 0.5-, 1-, 2-, and 3-mm STR boluses were 2.7, 4.4, 4.8, and 4.9 mm, respectively. There were no differences for those in lateral dose profiles. The 1-mm-thick STR thin bolus shifted the depth dose profile by 4.4 mm and could be used as a customized bolus for photon radiotherapy.

PURPOSE: The aim of this study is to investigate overdose to organs at risk (OARs) observed in dosimetry audits in Monte Carlo (MC) algorithms and Linear Boltzmann Transport Equation (LBTE) algorithms. The impact of penumbra modeling on OAR dose was assessed with the adjustment of MC modeling parameters and the clinical relevance of the audit cases was explored with a planning study of spine and head and neck (H&N) patient cases. METHODS: Dosimetric audits performed by the Australian Clinical Dosimetry Service (ACDS) of 43 anthropomorphic spine plans and 1318 C-shaped target plans compared the planned dose to doses measured with ion chamber, microdiamond, film, and ion chamber array. An MC EGSnrc model was created to simulate the C-shape target case. The electron cut-off energy Ecut(kinetic) was set at 500, 200, and 10 keV, and differences between 1 and 3 mm voxel were calculated. A planning study with 10 patient stereotactic body radiotherapy (SBRT) spine plans and 10 patient H&N plans was calculated in both Acuros XB (AXB) v15.6.06 and Anisotropic Analytical Algorithm (AAA) v15.6.06. The patient contour was overridden to water as only the penumbral differences between the two different algorithms were under investigation. RESULTS: The dosimetry audit results show that for the SBRT spine case, plans calculated in AXB are colder than what is measured in the spinal cord by 5%-10%. This was also observed for other audit cases where a C-shape target is wrapped around an OAR where the plans were colder by 3%-10%. Plans calculated with Monaco MC were colder than measurements by approximately 7% with the OAR surround by a C-shape target, but these differences were not noted in the SBRT spine case. Results from the clinical patient plans showed that the AXB was on average 7.4% colder than AAA when comparing the minimum dose in the spinal cord OAR. This average difference between AXB and AAA reduced to 4.5% when using the more clinically relevant metric of maximum dose in the spinal cord. For the H&N plans, AXB was cooler on average than AAA in the spinal cord OAR (1.1%), left parotid (1.7%), and right parotid (2.3%). The EGSnrc investigation also noted similar, but smaller differences. The beam penumbra modeled by Ecut(kinetic) = 500 keV was steeper than the beam penumbra modeled by Ecut(kinetic) = 10 keV as the full scatter is not accounted for, which resulted in less dose being calculated in a central OAR region where the penumbra contributes much of the dose. The dose difference when using 2.5 mm voxels of the center of the OAR between 500 and 10 keV was 3%, reducing to 1% between 200 and 10 keV. CONCLUSIONS: Lack of full penumbral modeling due to approximations in the algorithms in MC based or LBTE algorithms are a contributing factor as to why these algorithms under-predict the dose to OAR when the treatment volume is wrapped around the OAR. The penumbra modeling approximations also contribute to AXB plans predicting colder doses than AAA in areas that are in the vicinity of beam penumbra. This effect is magnified in regions where there are many beam penumbras, for example in the spinal cord for spine SBRT cases.

BACKGROUND To evaluate the impact of the planning target volume (PTV) density on treatment planning for lung Stereotactic Body Radiation Therapy (SBRT). MATERIAL AND METHODS The PTV coverage was analyzed in two groups of 40 lung SBRT patients. One group had PTV density 0.5 g/cm3. The treatments were planned in Pinnacle 9.10, using the collapsed cone convolution (CCC) algorithm. The prescribed dose was 60 Gy to the PTV in 4-8 fractions. Respecting constraint for the PTV coverage (D98% > 95%), we compared changes in the isodose line prescription, the number of monitor units (MU), maximum dose (Dmax), irradiated volume covered with 30 Gy (V30Gy), and the optimization planning volume (OPV). RESULTS For the same median values of the PTV coverage (98.3%), the differences are presented with median values between lower and higher density than 0.5 g/cm3. The isodose line prescription was 83 vs. 90% (p

The median lethal dose (LD50) and low lethal dose (LD10) are calculated in acute toxicity studies, as well as during specific activity assessment of some medicines. The aim of the study was to develop a procedure for using CombiStats to calculate LD50 and LD10. The authors proposed a step-by-step algorithm for processing bioassay results using the CombiStats biometric software (median effective dose determination model, probit analysis) with conversion of doses to simple fractions (fractions of the maximum dose) to calculate LD50 and LD10. They compared LD50 and LD10 calculation results obtained using CombiStats with those obtained using electronic spreadsheets according to the Bliss–Miller–Tainter–Prozorovsky method described in the State Pharmacopoeia of the Russian Federation (General Monograph 1.1.0014.15). It has been demonstrated that the use of CombiStats sometimes has advantages over the use of the pharmacoepoeial method.

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Intracavitary cervical brachytherapy delivers high doses of radiation to the target tissue and a portion of these doses will also hit the rectal organs due to their close proximity. Rectal dose can be evaluated from dosimetric parameters in the treatment planning system (TPS) and in vivo (IV) dose measurement. This study analyzed the correlation between IV rectal dose with selected volume and point dose parameters from TPS. A total of 48 insertions were performed and IV dose was measured using the commercial PTW 9112 semiconductor diode probe. In 18 of 48 insertions, a single MOSkin detector was attached on the probe surface at 50 mm from the tip. Four rectal dosimetric parameters were retrospectively collected from TPS; (a) PTW 9112 diode maximum reported dose (RPmax) and MOSkin detector, (b) minimum dose to 2 cc (D2cc), (c) ICRU reference point (ICRUr), and (d) maximum dose from additional points (Rmax). The IV doses from both detectors were analyzed for correlation with these dosimetric parameters. This study found a significantly high correlation between IV measured dose from RPmax (r = 0.916) and MOSkin (r = 0.959) with TPS planned dose. The correlation between measured RPmax with both D2cc and Rmax revealed high correlation of r > 0.7, whereas moderate correlation (r = 0.525) was observed with ICRUr. There was no significant correlation between MOSkin IV measured dose with D2cc, ICRUr and Rmax. The non-significant correlation between parameters was ascribable to differences in both detector position within patients, and dosimetric volume and point location determined on TPS, rather than detector uncertainties.

Eltrombopag has shown efficacy in the treatment of thrombocytopenia and poor graft function (PGF) after allogeneic hematopoietic cell transplantation (HCT) in retrospective observational studies, but is not approved for this indication. The cost of this drug is also a major concern in publicly funded health care systems. We collected data about patients who received eltrombopag for thrombocytopenia or PGF after HCT. Post-HCT thrombocytopenia, PGF, and eltrombopag response were defined as per previously published criteria. Primary outcome was treatment efficacy and secondary outcome was cost comparison between estimated treatment cost prior to and after initiation of eltrombopag. Seventeen patients (males 70.6%; median age = 58) received eltrombopag. Isolated thrombocytopenia was present in 11.8% (n = 2) patients while PGF was present in 88.2% (n = 15) of patients. After 8 weeks of treatment at the maximum dose of 150 mg orally daily, overall response rate (ORR) was seen in 76.5% (13/17) of patients: complete response (CR) in 10/13 patients and partial response (PR) in 3/13 patients. The use of eltrombopag was associated with an overall decrease in the total weekly care costs (5021 vs 2,524 CA$; P = 0.04). Thus, Eltrombopag is an efficacious and possibly cost-effective therapy for thrombocytopenia and PGF after allogeneic HCT.

Radiation protection and safety documents for routine conditions are required to support the licensing requirements for nuclear power plant site. This research is focused in the assessment and analysis of the results of PWR safety study related to the routine release of radioactivity from the SMR subsystems and components of the 100 MWe-type PWR along with its consequences in the site. The core inventory calculation was done using ORIGEN2 software, applying release parameters from the existing analysis and calculation results. The radiological consequences were calculated by the PC-CREAM program package. Environmental and meteorological data were obtained using Arc-GIS and spatial analysis. The Bangka Belitung (Babel) site was used as the specific footprint. Analyzing PC-CREAM output data the radiological consequences of routine operation of 3 100 MWe PWR modules on Sebagin site (South Bangka) and Muntok site (West Bangka) in 16 sectors and within a radius of 20 km were concluded. The calculation results for the Sebagin site is that the maximumdose within a radius of 500 m (exclusion zone) is 1.15E+02 µSv/year. For a radius beyond 500 m, the maximum dose is 4.71E+01 µSv/year. Whereas for Muntok site (West Bangka), the maximum dose in the exclusion area (500m) is 3.10E+00 µSv/year. The individual dose for the Babel site in the exclusion area is below the dose constraint for non-radiation service workers as the general public of 0.3 mSv/year or 300 µSv/year, while the maximum dose for outside exclusion is also below the constraint as stipulated in BAPETEN Regulation No 4 Year 2013 on Radiation Protection and Safety.

Many human cancers predominantly metastasize to the bone which causes bone pain and other symptoms. However, the management of bone metastases is challenging. Radionuclide therapy using low-energy beta-emitting radionuclides has yielded encouraging results. The aim of this therapy is to deliver the maximum dose to the metastatic sites but a minimal dose to the normal tissue. Samarium-153 [153Sm]Sm-Ethylenediamine tetramethylene phosphonate (EDTMP) is an FDA and European Medicine Agency approved (Quadramet) radionuclide and is widely used for bone pain palliation. 153Sm is reactor produced, and the presence of europium impurities is thus unavoidable. This in turn causes an increase in the hospital radioactive waste burden and in radiation absorbed doses to the patients, and therefore it is a concern. The effective removal of these impurities is thus highly desirable before its administration to the patients. In this article, we present a detailed review of the various methods described in the literature for separation of 153Sm and Eu, that is solvent extraction, ion-exchange chromatography, electrochromatography, electrochemical separation and supported ionic liquid phase.

This paper assesses radiation exposures resulting from 137Cs, 241Am, and 252Cf during well logging incidents. Based on a hypothetical rupture incident, the computer code RESRAD-OFFSITE is run for both offsite and onsite exposure locations. The absorbed doses are compared among three radioactive sources. The adverse health and environmental impact of 241Am is higher than the impact from the other two radioactive sources (137Cs and 252Cf) due to its relatively long half-life and radioactive progeny. The serious impact of 241Am will appear many years after its abandonment depending on its initial activity in the soil. For offsite, the highest maximum dose is due to 241Am (6.18 mSv y-1), which is more than 22 times the maximum doses from 137Cs and 252Cf. For onsite, the highest maximum doses are due to 241Am (121 mSv y-1), which is more than twice the maximum doses from 137Cs and 252Cf. For offsite and onsite, the dominant pathway for 137Cs is direct radiation from soil, the dominant pathway for 241Am is drinking water followed by plant ingestion, and the dominant pathway for 252Cf is direct radiation from soil. Doses from 137Cs and 252Cf are mainly impacted by the contamination on the surface. For 241Am, the opposite is true. Americium-241 doses are mainly impacted by the contamination below the surface. Based on these findings, the exposure impact for replacing an 241Am neutron source for well logging with 252Cf is assessed.

In the present study, 222Rn activity concentrations in a newly formed underground tourist route under Książ castle, Poland, were investigated for periods undisturbed and disturbed by construction works. This preliminary assessment is based on the almost 3-year long continuous measurements (28 Oct. 2016–02 Jul. 2019) done with an SRDN-3 instrument. In detail described are radon concentrations for periods of renovation (11 Aug. 2018–10 Oct. 2018), opening (15 Oct. 2018–10 Apr. 2019) and operation and monitoring (11 Apr. 2019–02 Jul. 2019) of the facility. It was observed that after the termination of construction work, when natural ventilation returned to the state preceding this work, the absolute values of radon activity concentration decreased. The mean annual radon concentrations were higher than the reference level of radon concentration in underground spaces recommended by IAEA, ICRP, and by the EU Council Directive for workplaces. They reached 1179 Bq/m3 and 943 Bq/m3 in 2017 and 2018, respectively. Cyclically recurring daily changes in radon concentrations occurred only in April and October (so-called transitional periods) and only outside the period of construction work. The results confirmed; however, that these changes need not be considered when planning the work in the tunnel. The minimum effective dose rate from radon exposure occurs in colder periods of the year, from November to the end of March, where the mean effective dose rate value was found to be 0.0003 mSv/h. In contrast, the maximum dose rate of 0.014 mSv/h was observed from April to August.

Purpose This study compared the applicator position relative to the tracheal wall and dosimetric parameters between conventional and novel applicators among patients receiving endobronchial brachytherapy (EBBT) for intratracheal tumors. Methods and Materials Data from 7 patients who received EBBT for intratracheal tumors were retrospectively analyzed; 4 and 3 patients were treated with conventional (2-wing) or novel (5-wing) applicators, respectively. Applicator centrality was evaluated using the distance between the center of the trachea and main bronchus (TMB) lumen and path of source (L). Dosimetric parameters, including plans normalized to D2cc of the TMB = 45 Gy (normalized plan), were compared between the applicators. Results The mean and maximum values of L in cases of the 2-wing applicator group were approximately 5.0 mm and 10.0 mm, respectively. In the novel applicator group, the corresponding values were approximately 3.0 and 6.0 mm, respectively. In the normalized plan of the 2-wing applicator group, the ranges of median V90% of clinical target volume (CTV) and D0.1cc of the TMB in all cases were 23.0–91.9% and 66.3–153.1 Gy, respectively. In the 5-wing applicator group, the corresponding values were 69.2–83.8% and 60.4–84.5 Gy, respectively. Conclusions In the 5-wing applicator group, the range was narrow in all dose–volume parameters except for D2cc of the TMB. Compared to the conventional applicator, the 5-wing applicator can give a stable dose to the CTV and can reduce the maximum dose of the TMB. This suggests that stable EBBT can be given to any patient using the 5-wing applicator.

BACKGROUND: Stereotactic radiosurgery (SRS) is increasingly used for management of perioptic meningiomas. OBJECTIVE: To study the safety and effectiveness of SRS for perioptic meningiomas. METHODS: From 12 institutions participating in the International Radiosurgery Research Foundation (IRRF), we retrospectively assessed treatment parameters and outcomes following SRS for meningiomas located within 3 mm of the optic apparatus. RESULTS: A total of 438 patients (median age 51 yr) underwent SRS for histologically confirmed (29%) or radiologically suspected (71%) perioptic meningiomas. Median treatment volume was 8.01 cm(3). Median prescription dose was 12 Gy, and median dose to the optic apparatus was 8.50 Gy. A total of 405 patients (93%) underwent single-fraction SRS and 33 patients (7%) underwent hypofractionated SRS. During median imaging follow-up of 55.6 mo (range: 3.15-239 mo), 33 (8%) patients experienced tumor progression. Actuarial 5-yr and 10-yr progression-free survival was 96% and 89%, respectively. Prescription dose of ≥12 Gy (HR: 0.310; 95% CI [0.141-0.679], P = .003) and single-fraction SRS (HR: 0.078; 95% CI [0.016-0.395], P = .002) were associated with improved tumor control. A total of 31 (10%) patients experienced visual decline, with actuarial 5-yr and 10-yr post-SRS visual decline rates of 9% and 21%, respectively. Maximum dose to the optic apparatus ≥10 Gy (HR = 2.370; 95% CI [1.086-5.172], P = .03) and tumor progression (HR = 4.340; 95% CI [2.070-9.097], P

On basis of dosimetric measurement, this article compares the radiation doses received by the main interventional cardiologist during the angiographic procedures. The dose load during three procedures is compared—LAD-stenting, LCx-stenting and RCA-stenting. An angiographic X-ray system Philips Allura Xper FD10 (with G-arm) was used. The dose obtained was measured with an X-ray-Gamma Dosimeter 27091. During each procedure, two modes of the equipment are used—radiography and fluoroscopy. The dose measurements were made for the respective projections of each angiographic procedure and for the operation modes of the equipment used during the respective procedure at three measurement points on the operator’s body—head, gonads and feet and at three position of the patient’s table—lowest, highest and zero. The results obtained from the calculations, based on the measured dose values, show maximum dose load in the procedure that uses the radiographic mode of operation for the longest time, namely RCA-stenting. The other two procedures have the same time on radiography and fluoroscopy. From them a higher dose load was obtained for the procedure LAD-stenting. Of the three procedures studied, the lowest dose load is obtained for the procedure LCx-stenting.

The purpose of this work was to evaluate using Varian HyperArc as a planning and treatment solution for whole brain radiotherapy (WBRT) with hippocampal sparing following Radiation Therapy Oncology Group (RTOG) 0933 dosimetric criteria. Ten patients previously treated for intracranial lesions were retrospectively planned for WBRT with hippocampal sparing using HyperArc and a 2-arc coplanar VMAT technique. The whole brain and hippocampus were delineated on fused MRI and CT datasets. The planning target volume (PTV), defined as the whole brain excluding the hippocampal avoidance region, was prescribed 30 Gy in 10 fractions. Plans were evaluated using dosimetric parameters which included the volume of 105% of the prescription dose (V105%) and the maximum dose to the PTV, and the minimum dose to the hippocampus. The planning time, delivery time, and delivery quality assurance (QA) results were also evaluated. Statistical significance was performed between the HyperArc and coplanar VMAT metrics using the Wilcoxon signed-rank test with a significance level of 0.05. All plans met RTOG 0933 dosimetric criteria. HyperArc plans demonstrated significant improvements in PTV dosimetric quality which included a reduced V105% of 6 ± 7% and decreased maximum dose of 1.3 ± 0.3 Gy, compared to coplanar VMAT. Significant OAR sparing was also found for HyperArc plans that included a decreased minimum dose to the hippocampus of 0.3 ± 0.3 Gy. Coplanar VMAT plans resulted in significantly shorter planning and delivery times, compared to HyperArc, by 2.4 minutes and 1.5 minutes, respectively. No significant difference was found between the delivery QA results. This study demonstrated using Varian HyperArc as a planning and treatment solution for WBRT with hippocampal sparing following RTOG 0933 dosimetric criteria. The primary advantages of WBRT with hippocampal sparing using HyperArc, compared to coplanar VMAT, are the gains in OAR sparing and reduced high dose volumes to the PTV.

The main goal of the article is to compare the effective radiation doses received by the leading interventional cardiologist during the angiographic procedures. A comparison is done between the dose load during three procedures—LAD-stenting, LCx-stenting and RCA-stenting. An angiographic X-ray system Philips Allura Xper FD10 (with G-arm) was used for this study. The dose obtained was measured with an X-ray-Gamma Dosimeter 27091. The dose measurements were made for the respective projections of each angiographic procedure and for the operation modes of the equipment used during the respective procedure at three measurement points on the operator’s body—head, gonads and feet. The results obtained from the calculations, based on the measured dose values, show maximum dose load in the procedure that uses the radiographic mode of operation for the longest time, namely RCA-stenting.

Background Newer technology for stereotactic radiosurgery (SRS) should be assessed for different multi-leaf collimators (MLC). Objective Assess plan quality of an automated, frameless, linear accelerator based (linac) planning and delivery system (HyperArc) for SRS using both standard MLC (SMLC) and high definition MLC (HDMLC) compared to a cobalt-60 based SRS system (Gamma Knife, GK). Methods We re-planned twenty GK Perfexion-treated SRS patients (27 lesions) for HyperArc using SMLC and HDMLC. We assessed plan quality using the following metrics: gradient index (GI), Paddick and RTOG conformity indices (CIPaddick, CIRTOG), volume receiving half of prescription isodose (PIVhalf) and maximum dose to 0.03 cc for brainstem, optic chiasm and optic nerves, and V12Gy for brain-GTV. Results Linac plans had better conformity with HDMLC being most conformal. GK exhibited better GI. PIVhalf demonstrated no statistically significant difference between HDMLC and GK, and SMLC was nominally worse than GK. Mean PIVhalf was generally 0.85 cc larger for SMLC than HDMLC. For TV > 1.0 cc, the relative differences in CIRTOG, GI, and PIVhalf for SMLC vs. HDMLC were less than 21%. For TV less than Conclusions New linac-based plans positively compare to GK plans overall. HDMLC should be strongly considered for treatment of lesions

Purpose and objective Auto planning might reduce the manual time required for the optimization and could also potentially improve the overall plan quality. The aim of this study is to demonstrate the statistical comparison of automatic (AU) and manually (MA) generated nasopharyngeal carcinoma (NPC) intensity-modulated radiation therapy (IMRT) plans. Materials and methods The study included 105 nasopharyngeal carcinoma patients, admitted to our hospital. The patients underwent IMRT treatments. The clinically delivered plans were performed with Eclipse (Version 11.0) using manual optimization. The same plans were optimized successively in PinnacleTM3 (version 9.10) treatment planning system using the auto plan software package module. D95 (dose of 95% volume) and D98 (dose of 98% volume) were calculated for the targets and maximum dose (Dmax) and mean dose (Dmean) for the organ at risks (OARs); moreover, the average doses of each target and OARs for 105 patients were evaluated. Results There is no significant difference in the homogeneity of the target between AU and MA treatment plans, while a significant difference is observed for what is concerning the OARs or most of OARs in 105 patients, OAR doses were significantly reduced in AU plan. For OARs which have no significant difference between AU and MA plans are highlighted, the mean dose of OARs in AU plans was at least not higher than MA plans. Conclusion Nasopharyngeal carcinoma IMRT plans made by an automatic planning tool met the clinical requirements for target prescription dose; moreover, the dose of normal tissues was lower than in MA plans. Clinical physicists' time can be saved and the influence of factors such as the lack of experience in treatment planning can be avoided.

The aim is to make an adequate estimate of the ambient equivalent dose received by the groups closest to the patient, once the patient has the radiological and clinical discharge. As a first step, a patient's daily life pattern with its closest environment has been modelled. A maximum dose rate of 40 μSv/h at 1 meter has been set to give the patient the radiological discharge. Secondly, a fitting equation that gives us the evolution of the dose rate with distance has been formulated. How the function fits to the experimental points after measuring 45 patients at the distances between 0.4 and 2 meters was verified obtaining R2 ≥ 0.98 for 75.55% of the cases. Besides, a smaller error is made than using the equation of the Radiological Protection in the Healthcare Enviroment in 93.33% of cases. When models are simulated, modes of the dose distributions do not exceed the dose restriction, namely, 3 mSv per treatment when partner is under 60 years old and 15 mSv when companion is over 60 years old. Finally, an experimental elimination time is obtained, being this less than the given in the Forum document, reducing the mode of distributions between a half and one tenth.

This study aimed to assess whether a Monte Carlo (MC)-based algorithm reflects the influence of totally implantable venous access ports (TIVAPs) in external radiation therapy. The present study comprised two steps: experimental measurements of depth doses and surface doses with and without TIVAPs and calculation with an MC-based algorithm. The TIVAP-associated maximum dose reduction compared with the dose at the same depths without TIVAPs was 7.8% at 4 MV, 6.9% at 6 MV, and 5.7% at 10 MV in measurement, and 7.4% at 4 MV, 6.6% at 6 MV, and 5.5% at 10 MV in calculation. Relative surface doses were higher with TIVAPs made of titanium, due to a higher fluence of backscattered electrons from the TIVAPs, than with plastic TIVAPs. There were no significant differences in the relative differences between the measured and calculated doses of the titanium TIVAP group and the plastic TIVAP group at 4 MV (p = 0.99), 6 MV (p = 0.67), and 10 MV (p = 0.54). TIVAPs caused target dose reductions and dose increase near the TIVAP, especially when made of titanium. The influences are reflected in the MC-based algorithm.

Using a plane‐parallel advanced Markus ionization chamber and a stack of water‐equivalent solid phantom blocks, percentage surface and build‐up doses of Elekta 6 MV flattening filter (FF) and flattening‐filter‐free (FFF) beams were measured as a function of the phantom depth for field sizes ranging from 2 × 2 to 10 × 10 cm2. It was found that the dose difference between the FF and the FFF beams was relatively small. The maximum dose difference between the FF and the FFF beams was 4.4% at a depth of 1 mm for a field size of 2 × 2 cm2. The dose difference was gradually decreased while the field size was increased up to 10 × 10 cm2. The measured data were also compared to published Varian FF and FFF data, suggesting that the percentage surface and build‐up doses as well as the percentage dose difference between FF and FFF beams by our Elekta linac were smaller than those by the Varian linac.

Purpose To investigate and improve the level of equivalency of Varian TrueBeam linear accelerators (linacs) in energy‐, dosimetric leaf gap‐ (DLG) and jaw calibration. Methods Eight linacs with four photon energies: 6 MV, 6 MV FFF, 10 MV FFF, and 15 MV, and three electron energies (on two linacs): 6, 9, and 12 MeV were commisioned and beam‐matched. Initially, symmetry of lateral profiles was calibrated for maximum field size. Energy‐matching was then performed for photons by adjusting diagonal profiles at maximum field size and depth of maximum dose to coincide with the reference linac, and for electrons by matching the range at percentage depth of ionization of 90%, 80%, and 50%. Calibration of DLG was performed for 6 MV and evaluated among the linacs. The relationship between DLG and the Gap value was investigated. A method using electronic portal imaging device (EPID) was developed and implemented for jaw calibration. Results Symmetry calibration for photons (electrons) was within 1% (0.7%), further improving the vendor's acceptance criteria. Photon and electron energy‐matching was within 0.5% and 0.1 mm, respectively. Calibration of DLG was within 0.032 mm among the linacs and utilizing the relationship between DLG and the Gap value resulted in an empirical calibration method which was implemented to simplify DLG adjustment. Using EPID‐based method of calibration, evaluation of the jaw‐positioning among the linacs for 30 cm × 30 cm field size was within 0.4 mm and in the junction area within 0.2 mm. Dose delivery error of VMAT‐plans were at least 99.2% gamma pass rate (1%, 1 mm). Conclusions High level of equivalency, beyond clinically accepted criteria, of TrueBeam linacs could be achieved which reduced dose delivery systematic errors and increased confidence in interchanging patients among linacs.

The purpose of this study was to investigate the oxygen enhancement ratio (OER) effects on treatment planning for a hypoxic prostate tumor with proton scanning beams. Two different OER-based dose calculation models (the average model and the voxel model) were investigated by using hypoxic tumor models in this simulation study. For the hypoxic tumor model, an oxygen distribution with a range of 2.4–9.4 mmHg was used according to the clinical data. The results given by the average model and the voxel model were compared for 50% and 90% tumor control probabilities with variations in the hypoxic tumor volume and fractionation. Comparison between the treatment plans with OER-based higher predicted dose and with the conventional prescription dose was conducted to investigate the organ-at-risk (OAR) doses for the prostate case. The average model showed a higher calculated dose than the voxel model. The voxel model with a 50% control probability showed good agreement with the current prescription dose. The OER values of the average model ranged from 1.05 to 1.25, which were applied to the whole tumor volume in treatment planning. The voxel-model-based OERs were higher (1.50–1.75) than those of average model, and these OERs should be applied only for the hypoxic boost region. Regarding treatment plans, the doses of the rectum and the bladder were reduced to the tolerable range V80Gy (volume receiving equal to or greater than 80Gy) < 15% and V75Gy (volume receiving equal to or greater than 75Gy) < 15% respectively after an optimization, but the maximum dose to femoral heads was higher than 50 Gy. In conclusion, we investigated the possible ranges of the OER (1.3–1.8) for proton-beam treatment of prostate cases. A dose escalation of up to about 1.8 times can be applied for the small hypoxic region. This result, which was obtained using a model study, should be verified through clinical experiment.

OBJECTIVES: To compare the defervescence period of azithromycin versus ceftriaxone in children with enteric fever. METHODS: This open-label, randomized-controlled trial was conducted at Pediatrics Department, Federal Government Polyclinic Hospital, Islamabad, Pakistan from June 30, 2015 to December 30, 2015. Sample Size calculated was 99 by using WHO Sample Size Calculator. Patients of either gender, aging 2-12 years, diagnosed as enteric fever were eligible for study. One hundred eligible patients selected through non-probability consecutive sampling technique were recruited in the study, after seeking an informed consent from the parents. These patients were randomized through lottery method in two groups of equal size (n=50 each). Group A, received oral azithromycin suspension/capsule (10mg/kg/day; maximum dose, 500mg/day) administered once daily for 7 days, while Group B received intravenous (I/V) ceftriaxone (75mg/kg/day; maximum dose, 2.5 g/day) administered twice daily for 10 days. The clinical response to the therapy of both drugs was calculated in terms of number of days taken for defervescence. Data was analyzed in SPSS version 22.0. RESULTS: Out of 100 patients, 64 (64%) were males and 36 (36%) were females and mean age of patients was 7.08±3.013 years. Patients on azithromycin had the mean time of defervescence 4.08±0.922 days and patients on ceftriaxone, the mean time of defervescence was 4.06±1.038 (p=0.919). CONCLUSION: There is no significant difference between oral azithromycin and intravenous ceftriaxone in term of defervescence period for the treatment of enteric fever in children. azithromycin could be a suitable alternative owing to its convenient dosing and monitored on outpatient basis.

Purpose This study performed the accurate measurements of beam profiles with a new rigid board, which was consistent with the supplied reference beam profiles (RBPs) for clinical Halcyon model. Methods Percentage depth doses (PDDs), lateral and diagonal dose profiles were measured and compared with RBPs. A water tank was set on the rigid board bridged Halcyon bore without sagging and source-to-surface distance was 90.0 cm. Field sizes were from 2.0 to 28.0 cm squares and depths of lateral and diagonal dose profiles were 1.3, 5.0, 10.0, and 20.0 cm. For the PDD, the depth of maximum dose (dmax), PDD value at depth of 10.0 cm (PDD10), and absolute dose difference (DD) between RBP and measured beam profiles (MBP) were evaluated. For lateral and diagonal dose profiles, DDs for the whole and divided areas (central, shoulder, and extended areas) defined by third derivative, and distance-to-agreement (DTA) in the penumbra area were evaluated. Results For PDDs, the differences of dmax and PDD10 and DD beyond the dmax were within 1.0 mm, 0.3%, and 1.0%, respectively. For lateral and diagonal dose profiles, the DDs reached approximately 5.0% in the whole area because of penumbra area, while the DDs in the central, shoulder, and extended areas were within 1.0%, 2.0%, and 1.0%, respectively. The DTAs in the penumbra area were within 0.8 mm. Conclusions The supplied RBPs can be used clinically owing to the good agreement with the accurate MBPs with rigid board.

The concentration of dissolved radon gas was measured using the RAD7 device in drinking water sources in Zarand city and its villages. The mount of radon in drinking water sources was in the range of 5.16–14.4 BqL−1. The effective dose in all cases was less than the recommended maximum dose of 100 μSvY−1 by the WHO. Very poor linear relationship was found between the depth of wells and the radon concentration of the samples.

Purpose Studies on Lattice radiotherapy (LRT) for breast cancer have been largely lacking. This study investigates the dosimetric feasibility of using Gamma Pod, a stereotactic radiotherapy apparatus originally designed for breast SBRT, to deliver LRT to large, bulky breast tumor as a noninvasive treatment option. Methods The GammaPod-based LRT was simulated using Geant4 Gate Monte Carlo software. The simulated GammaPod was equipped with 5 mm diameter non-coplanar circular beams that span 28° latitudinally from 18° to 43° off the horizontal plane. Two degrees longitudinal intervals were used to simulate rotating sources. To simulate the treatments to different breast sizes, three water-equivalent hemisphere volumes with diameters of 10, 15, and 20 cm were analyzed. The lattice was planned by spacing focal points 2 cm apart in the transverse and sagittal planes and 2.5 cm in the coronal plane. This resulted in 22-172 shots for full breast treatment. The maximum dose for each individual shot was 20 Gy. The peak-to-valley dose differences and skin dose were analyzed. To verify the feasibility of delivering LRT, a test plan was created and delivered to a commercial diode array dose verification device using a clinical GammaPod system with 15 mm collimators. Results The dose profiles showed the average peak-to-valley dose percent differences of 94.10% in the 10 cm hemispherical volume, 88.95% in the 15 cm hemispherical volume, and 83.60% in the 20 cm hemispherical volume. Average skin dose was 1.27, 1.72, and 2.13 Gy for the 10, 15, and 20 cm irradiation volumes, respectively. The LRT plan delivered using a clinical GammaPod system with larger collimators verified the feasibility of LRT plan delivery. Conclusion GammaPod-based lattice radiotherapy is a viable treatment option and its application can be extended to treating large bulky breast tumors.

The aim of this study was to evaluate the dosimetric effect of continuous motion monitoring based localization (Calypso, Varian Medical Systems), gating and intrafraction motion correction in prostate SBRT. Delivered doses were modelled by reconstructing motion inclusive dose distributions for different localization strategies. Actually delivered dose (strategy A) utilized initial Calypso localization, CBCT and additional pre-treatment motion correction by kV-imaging and Calypso, and gating during the irradiation. The effect of gating was investigated by simulating non-gated treatments (strategy B). Additionally, non-gated and single image-guided (CBCT) localization was simulated (strategy C). A total of 308 fractions from 22 patients were reconstructed. The dosimetric effect was evaluated by comparing motion inclusive target and risk organ dose-volume parameters to planned values. Motion induced dose deficits were seen mainly in PTV and CTV to PTV margin regions, whereas CTV dose deficits were small in all strategies: mean ± SD difference in CTVD99% was –0.3 ± 0.4%, −0.4 ± 0.6% and –0.7 ± 1.2% in strategies A, B and C, respectively. Largest dose deficits were seen in individual fractions for strategy C (maximum dose reductions were −29.0% and –7.1% for PTVD95% and CTVD99%, respectively). The benefit of gating was minor, if additional motion correction was applied immediately prior to irradiation. Continuous motion monitoring based localization and motion correction ensured the target coverage and minimized the OAR exposure for every fraction and is recommended to use in prostate SBRT. The study is part of clinical trial NCT02319239.

Introduction: Angiography and angioplasty expose cardiologists to a high level of X-ray comparing other radiographic methods, due to the high dose of radiation and the presence of the physician beside the patient bed during the procedure. Therefore, this study was designed to measure the absorbed dose in some important organs and extremities in cardiologists during different angiography and angioplasty procedures in catheterization lab. Methods: The entrance skin dose and extremity absorbed dose of the physicians in 100 angiography and angioplasty procedures were measured by TLD chips. The points on the physicians’ body, which were measured in this study, included: thyroid, right and left chest, right and left wrists, and left leg. The correlation of entrance skin dose in these six points to the exposure parameters is also evaluated. Results: The left leg has maximum dose and maximum correlation with total DAP for all three physicians in all procedure types. There was a weak correlation between left wrist absorbed dose and number of views among three physicians. Also, the maximum annual absorbed dose of the physicians in the left leg was lower than 150 mSv. Conclusion: According to the results of this study, it can be stated that periodic leg and hand dosimetry during operation is necessary for interventional cardiologists. Results also showed that, regardless of the type of procedure, the characteristics of device output, especially DAP, have a direct role in the absorbed dose of the organs and extremities, especially those outside the shield.

Background: Radiotherapy is a radiation therapy action using ionizing radiation. To obtain the maximum dose of radiation in the tumour and the lowest possible dose on critical organs required a technique of radiation technique 3 Dimensional Conformal Radiotherapy (3DCRT). Radiotherapy Unit Radiology Installation Dr Sardjito Hospital Yogyakarta using 3DCRT technique. This research aims to know the radiotherapy procedure on paranasal sinus cancer using 3DCRT technique, to know the implementation of bolus beam modifier and dose optimization with the addition of electron radiation.Methods: The type of research in this thesis is qualitative research with case study approach. The research was conducted at Radiotherapy Unit Radiology Installation Dr Sardjito Hospital Yogyakarta after published Ethical Clearance. Methods of data collection in this study are observation, interviews, and documentation.Result: The results of this study indicate that the radiotherapy procedure in paranasal sinus cancer using 3DCRT technique can produce a homogeneous dose distribution, the implementation of bolus beam modifier is capable of generating dosage homogeneity on uneven target surfaces, and the distribution of doses with electron radiation on the target in the surface area can be optimal.Conclusion: With these techniques, the goal of radiotherapy can be achieved is to give the maximum dose in the tumour and the minimum dose possible in healthy tissue located in the vicinity.

Aim The aim is a dosimetric comparison of dynamic conformal arc integrated with the segment shape optimization and variable dose rate (DCA_SSO_VDR) versus VMAT for liver SBRT and interaction of various treatment plan quality indices with PTV and degree of modulation (DoM) for both techniques. Background The DCA is the state-of-the-art technique but overall inferior to VMAT, and the DCA_SSO_VDR technique was not studied for liver SBRT. Materials and methods Twenty-five patients of liver SBRT treated using the VMAT technique were selected. DCA_SSO_VDR treatment plans were also generated for all patients in Monaco TPS using the same objective constraint template and treatment planning parameters as used for the VMAT technique. For comparison purpose, organs at risk (OARs) doses and treatment plans quality indices, such as maximum dose of PTV (D max %), mean dose of PTV (D mean %), maximum dose at 2 cm in any direction from the PTV (D 2cm %), total monitor units (MU’s), gradient index R 50% , degree of modulation (DoM), conformity index (CI), homogeneity index (HI), and healthy tissue mean dose (HTMD) were compared. Results Significant dosimetric differences were observed in several OARs doses and lowered in VMAT plans. The D 2cm %, R 50% , CI, HI and HTMD are dosimetrically inferior in DCA_SSO_VDR plans. The higher DoM results in poor dose gradient and better dose gradient for DCA_SSO_VDR and VMAT treatment plans, respectively. Conclusions For liver SBRT, DCA_SSO_VDR treatment plans are neither dosimetrically superior nor better alternative to the VMAT delivery technique. A reduction of 69.75% MU was observed in DCA_SSO_VDR treatment plans. For the large size of PTV and high DoM, DCA_SSO_VDR treatment plans result in poorer quality.

Purpose To investigate the daily setup, interfraction motion, variability in the junction areas, and dosimetric effect in craniospinal irradiation (CSI) patients. Methods Fifteen CSI patients who had undergone split‐field IMRT were followed in the study. Previous, middle, and posttreatment, each target volume position was evaluated using the ExacTrac system. Interfraction and intrafraction motions, the margin of the junction in adjacent targets volumes, and the dosimetric effect of the longitudinal residual error were analyzed. Results The lowest attainment rate within the tolerance of the initial setup error was 66.79% in six directions. The values of the initial error were within 15 mm (SD 4.5 mm) in the translation direction and 5° (SD 1.3°) in the rotation direction after the transposition of the treatment isocenter. With the guidance of the ExacTrac system, the interfraction and intrafraction residual errors were almost within the tolerance after correction, the margin of CTV‐to‐PCTV was in the range of target expansion criteria. The residual longitudinal errors resulted in only slight changes in the mean doses of PGTV and PCTV, while the maximum dose of the spinal cord increased by 16.1%. The patients did not exhibit any side‐effects by the overall treatment during the follow‐up period. Conclusions Position correction is necessary after setup and the transposition of the treatment isocenter. Intra‐fraction motion in the lateral direction should be monitored throughout treatment. The position errors in junction areas are almost within the tolerance after correction. The patients did not exhibit any side‐effects by the overall treatment.

Aripiprazole is an antipsychotic drug with unique pharmacological properties showing ago-antagonistic effects against the D2 receptor and is classified as a III generation antipsychotic. Clinical and preclinical studies indicate efficacy and safety of high doses of aripiprazole in selected patients, supporting the decision to use the drug at a maximum dose of 30 mg/day. This paper presents the mechanism of action of high doses of aripiprazole and discusses clinical situations when it is appropriate to use the drug at the maximum dose. The second part of the study presents arguments for beneficial effects of the combination of aripiprazole with olanzapine and other antipsychotic drugs of II generation.

Aim:To modify the final dose delivered to superficial tissues and to modulate dose distribution near irradiated surface, different boluses are used. Air gaps often form under the bolus affecting dose distribution. This study aimed to evaluate the effect of an air gap under the bolus radiation on dose delivery.Materials and methods:To evaluate the impact of the air gap, both helical tomotherapy (HT) and direct tomotherapy (DT) were performed in a simulation study.Results:The maximum dose to bolus in DT plans was bigger than that used in HT plans. The maximum dose delivered to the bolus depended on the air gap size. However, the maximum dose to bolus in all HT plans was within the acceptable value range. Acceptable value was set to up to 107% of the prescription dose. In the simulation performed in this study, the acceptable air gap under bolus was up to 15 mm and below 5 mm in HT and DT plans, respectively.Conclusions:HT technique is a good choice, but DT technique can be also used if the bolus position can be reproduced accurately. Thus, the reproducibility of the bolus position between planning and treatment is very important.

Objectives: To study the effect of oral iron chelator on serum ferritin level in patients with thalassemia major, we see the dose and frequency of oral iron chelator and its effect on serum ferritin and BT (Blood transfusion) iron overload. Material and Methods: Patients with thalassemia with 5-18 year of age are taken in our study. Total numbers of patients taken are 50.1st Group is with BT iron overload of 0.2-0.3mg/kg/day is given oral iron chelator in the dose 20mg/kg/day & serum ferritin should be overload of >0.3mg/kg/day is given oral iron chelator in the dose 30mg/kg/day & serum ferritin should be >1500ng/ml. Oral iron chelator is given according to serum ferritin level which is done at frequent intervals. Oral iron chelator is given as per serum ferritin level and maximum dose of oral iron chelator is 40 mg/kg/day. We study the dose of oral iron chelator, change in serum ferritin level and its effects on BT iron overload. Results: Number of patients with BT iron overload in the range of 0.2-0.3 mg/kg is n=25(50%) in 1st Group. Number of patients with BT iron overload in the range of >0.3-0.4 mg/kg is n=15(30%) in 2nd Group. Number of patients with BT iron overload is more than 0.4 is n=10 (20%) in 3rd group. Calculated probability of average dose of oral iron chelator is 3rd group. There is significant decrease in serum ferritin level in 3 groups when we compare it with our beginning level (calculated probability BT iron overload, but BT iron overload is depend on dose of oral iron chelator. Serum iron concentration is also lowered as there is increase in dose of oral iron chelator. Conclusions: In our study we can say that oral iron chelator which can reduce serum ferritin level maximally was 30 mg/kg/day and showing very less side effects (BT iron overload taken for consideration was 0.3-0.4mg/kg/day). Oral iron chelator should be given less than 30mg/kg/day in patients having less BT frequency and less BT iron overload. Keywords: Thalassemia, Oral