Objective: The literature has approved that the use of the concept of diagnostic reference level (DRL) as a part of an optimization process could help to reduce patient doses in diagnostic radiology comprising the Computed Tomography (CT) examinations. There are four public/governmental CT centers in the province (Semnan, Iran) and, to our knowledge, after about 12 years since the launch of the first CT scanner in the province there is no dosimetry information on those CT scanners. The aim of this study was to evaluate CT dose indices with the aim of the establishment of the DRL for head, chest, cervical spine, and abdomen-pelvis examinations. Methods: Scan parameters of 381 patients were collected during two months from 4 CT scanners. The CT dose index (CTDI) was measured using a calibrated ionization chamber on two cylindrical poly methyl methacrylate (PMMA) phantoms. For each sequences, weighted CTDI (CTDIw), volumetric CTDI (CTDIv) and dose length product (DLP) were calculated. The 75th percentile was proposed as the criterion for DRL values. Results: Proposed DRL (CTDIw, CTDIv, DLP) for the head, chest, cervical spine, and abdomen-pelvis were (46.1 mGy, 46.1 mGy, 723 mGy × cm), (13.8 mGy, 12.0 mGy, 377 mGy × cm), (40.0 mGy, 40.0 mGy, 572 mGy × cm) and (14.9 mGy, 12.1 mGy, 524 mGy × cm), respectively. Conclusion: Comparison with the others results from the other countries indicates that the head, chest and abdomen-pelvis scans in our region are lower or in the range of the other studies investigated in terms of dose. In the case of cervical spine scanning it’s necessary to review and regulate scan protocols to reach acceptable dose levels.

Background: Breast cancer is the most prevalent cancer in women all over the world. The most common and effective treatment for the early stage of breast cancer patients is breast conserving surgery (BCS) followed by radiotherapy. Objectives: The aim of this study is to evaluate and compare the dosimetric parameters of three-dimensional conformal radiation therapy (3D-CRT), using virtual wedge and field in field (FIF) techniques for patients having left breast cancer in early stages. Methods: Twenty-four patients with left breast cancer participated in this study. They were divided into thr3ee categories (small, medium, and large) based on breast volume: ≤ 1500 cc small, 1500-2000 cc medium, and > 2000 cc large. Two treatment planning techniques were generated for each patient by prowess treatment planning system. The following parameters were compared: Maximum, minimum, and mean dose in planning target volume (PTV), homogeneity (HI) and conformity indexes (CI), percentage of volume receiving greater than 107% of the prescribed dose (hot spots) and less than 95% of the prescribed dose (cold spots), and total monitor unit (MU) and doses received to organs at risks (OARs) such as heart and left lung. The mean values were compared using student's t-test. Results: The FIF technique reduced either the maximum dose in PTV or hot spots in all groups significantly (P < 0.05). Conformity index and cold spots in conformal technique were significantly better than FIF technique in all groups (P < 0.05). Other parameters such as MU, HI, and doses received by OARs did not show any significant difference between two methods in all groups (P > 0.05). Conclusions: It is recommended that two techniques can be combined and used together to cover their weak points. Also, it seems that if there is no equipment of intensity modulated radiation therapy (IMRT) techniques such as FIF in some centers, conformal technique by using virtual wedge is a proper alternative.

Background: Despite the benefits of contrast-enhanced computed tomography (CT) scans in better tumor volume delineation, it can affect the accuracy of dose calculation in radiation therapy. This study examined this effect on a thorax phantom. Objectives: The influence of different variables including the concentrations of the Visipaque contrast media, tumor sizes, and CT scan energies on the dose measurement was examined. Methods: Transparent cylinders containing the contrast media were inserted in the lung area of the phantom and the CT scans were made. Non-enhanced CT scans were also acquired. Treatment planning using 2 opposite fields was performed on the CT scans and the doses were calculated in the treatment planning system. The results of the 2 sets of enhanced and non-enhanced CT scans were compared. Results: The correlation between concentration and the percentage of mean dose of the tumor volume was significant in 2 of the tumor sizes. The differences in the mean doses of the 2 plans were examined and more than 3% increase was observed in higher concentrations of the contrast media. Conclusions: According to this study, the suitable concentration of the contrast media administered and the CT scan energy should be considered. This would help to decrease the discrepancies between the calculated and delivered dose in radiotherapy treatments to a clinically acceptable level. The importance of time delays for CT scans after administration of the contrast media is emphasized.

Intussusception is a condition in which a segment of the gastrointestinal tract invaginates into the lumen of another segment. Adult intussusception is less common than juvenile intussusception in terms of cause, appearance, and treatment. Because the clinical picture can be quite atypical and difficult to interpret, it is frequently misdiagnosed at first. Herein, we report the case of a previously healthy 23‐year‐old female patient who presented to the Emergency Department (ED) with acute abdominal pain, vomiting, and diarrhea for 1 day following her last menstrual period. Ileocecal intussusception was discovered throughout the investigation. She was rushed for open abdominal surgery. Meckel's diverticulum was found as a pathologic lead point in the resected specimen, with no evidence of malignancy. Although intussusception is rare in adults, it should be considered in patients who have nonspecific stomach pain.

Background: Respiratory movement and the motion range of the diaphragm can affect the quality and quantity of prostate images.Objective: This study aimed to investigate the magnitude of respiratory-induced errors to determine Dominant Intra-prostatic Lesions (DILs) in positron emission tomography (PET) images. Material and Methods:In this simulation study, we employed the 4D NURBSbased cardiac-torso (4D-NCAT) phantom with a realistic breathing model to simulate the respiratory cycles of a patient to assess the displacement, volume, maximum standardized uptake value (SUV max ), mean standardized uptake value (SUV mean ), signal to noise ratio (SNR), and the contrast of DILs in frames within the respiratory cycle.Results: Respiration in a diaphragm motion resulted in the maximum superiorinferior displacement of 3.9 and 6.1 mm, and the diaphragm motion amplitudes of 20 and 35 mm. In a no-motion image, the volume measurement of DILs had the smallest percentage of errors. Compared with the no-motion method, the percentages of errors in the average method in 20 and 35 mm-diaphragm motion were 25% and 105%, respectively. The motion effect was significantly reduced in terms of the values of SU-V max and SUV mean in comparison with the values of SUV max and SUV mean in no-motion images. The contrast values in respiratory cycle frames were at a range of 3.3-19.2 mm and 6.5-46 for diaphragm movements' amplitudes of 20 and 35 mm. Conclusion:The respiratory movement errors in quantification and delineation of DILs were highly dependent on the range of motion, while the average method was not suitable to precisely delineate DILs in PET/CT in the dose-painting technique.

Word or Tex form) to their personal website or institutional repository. Authors requiring further information regarding CASRP΄s archiving and manuscript policies encouraged to visit: http://www.casrp.co.uk/journals Abstract Medical linear accelerators are one of the most widespread methods for cancer treatment. Despite their advantages, unwanted photoneutrons are produced by high energy linacs. This photoneutrons are as undesired doses to patients and a significant problem for radiation protection of the staffs and patients. Photoneutrons radiological risk must be evaluated because of their high LET and range.in order to achieving this aim, photoneutron spectrum are calculated. The head of linac and a common treatment room was simulated by the MC code of MCNPX. Photoneutron spectrum was calculated in different field sizes, distances from isocenter and different cases (with and without structures and materials such as flattening filter, compensator, air and treatment room walls). The inclusion of the flattening filter and compensator had not any effects on shaping the photoneutron spectrum but neutron fluence and the average neutron energy are reduced obviously. Also effect of air on photoneutron spectrum was negligible. The calculation of photoneutron spectrum with concrete walls show that the component of fast neutrons is decreased and thermal neutrons are increased due to the room-return. In this case, with increasing distance from isocenter, fast neutrons are decreased and thermal neutrons are increased. As the field size is increased from 5×5 to 15×15 cm 2 , the neutron flux is increased clearly in isocenter. The neutrons flux are decreased near the door due to maze effect. The photoneutron spectrum investigation and risk estimation due to inclusion of neutron contamination in treatment room prevent from secondary cancer mortality.

BackgroundAccelerated partial breast irradiation (APBI) is a method in which just bed of lumpectomy with a margin of 1–2 cm is irradiated. Regarding advantages of APBI to whole-brain radiation therapy (WBRT) and limitations for performing other techniques, we compare external beam radiation therapy (EBRT) with three-dimensional conformal radiation therapy (3DCRT), as a type of APBI technique.MethodsDosimetric parameters including uniformity index (UI), conformity index (CI), and homogeneity index (HI) beside heart and lung doses were assessed and compared in two techniques. CT images of 24 patients with left-sided breast cancer after lumpectomy were selected. Patients were categorized into three groups based on the volume of breast, respectively, ≤ 1000 cc, 1000–1500 cc, and ≥ 1500 cc. CI, HI, UI and DVH were calculated by DosiSoftIsogray treatment planning software.ResultsResults show the value of UI in APBI method is more than EBRT method significantly (p=0.004). Moreover, that CI in APBI method was more than EBRT (p=0.0000) and nearer to 1. There was no significant difference between HI values between APBI and EBRT methods. As the volume of breast gets bigger, HI values rise, meaning worse homogeneity.ConclusionAPBI method may be a good method for minimizing side effect and minimizing treatment periods.

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