Iranian Journal of Medical Physics
Volume:19 Issue: 3, May-Jun 2022

Ionising radiation in diagnostic and therapeutic radiology is steadily increasing, with clear significant benefits. However, the issues of unwanted radiation exposure to patients and medical workers, which has a hugely deleterious effect, remain a challenge that requires urgent attention. Thus, this study aimed to evaluate the possible radioprotective potential of Drymaria cordata (DC) extract on mice’s hematological parameters following exposure to X-ray radiation and investigate its ability to increase the survival rate.
Sixty female mice weighing 38-45g, 10-12 weeks old, were used for this study. The mice were divided into six different groups containing ten mice, sub-divided into irradiated and un-irradiated groups. The animals received 250mg/kg extract of DC by oral gavage for thirteen days in addition to feeding and water ad libitum. Mice were irradiated at the Radiotherapy and Oncology Department of Grey’s Hospital using a linear accelerator. Blood samples were collected at different time intervals for the hematology test with post-irradiation monitoring for 30 days.
Exposure of mice to 4Gy and 8Gy of X-ray radiation produced significant changes in the mice’s erythrocytes, hematocrit, leukocytes and platelets in a dose and time-dependent manner compared with the control (CNT) group. The present study revealed a progressive decrease in all the hematological parameters until 30 days among the irradiated groups. However, animals treated with DC extract before irradiation and animals who received extract only exhibited a significant time-dependent increase in the studied hematological parameters compared to the animals in the CNT group. Furthermore, the pre-treatment of mice with the DC delayed the onset of mortality, thereby increasing the mice's survival rate compared with the irradiated control.
Our findings showed that DC is a potent natural radioprotective agent through its ability to reduce radiation-induced damage in mice’s hematopoietic system and increase the survival rate.

The main objective of this study was to assess the impacts of an increasing the number of IMRT beams on cardiac dose distribution in left-sided breast irradiation so that we can reduce the heart’s mean dose  up to clinically acceptable level. For this study 107 female patients, diagnosed with left-sided breast cancer were selected retrospectively. In 107 patients, there were 52 patients of chest wall irradiation including supra-clavicular fossa, while 22 patients were of breast-conserving surgery excluding supra-clavicular fossa and internal mammary lymph nodes, and 33 patients were of chest wall irradiation including internal mammary lymph nodes and supra-clavicular fossa. Exclusion criteria were previous history of left-sided breast radiation therapy, uncommon fractionated dose delivered in past, and indication of palliative radiation therapy. Intensity modulated radiotherapy plans were generated using 7, 9 and11 beams for each patient and the prescribed dose was 40.05 Gy in 15 fractions (2.67 Gy /fraction) for the targets. Heart: V5Gy(cc): This was a low-dose volume of our study in which the 11-bIMRT technique yielded better result as compared to 9- and 7-bIMRT. Maximum and minimum values of V5 were found 539.60cc in 9-bIMRT and 141.32cc in 11-bIMRT techniques respectively.V25Gy(cc): The maximum value of V25Gy was found 41.73cc in 7-bIMRT technique, while the lowest value was 0.29cc in 11-bIMRT. The IMRT technique with 11 beams showed comparatively better result on this parameter as well as 3-5cc volume of V25Gy was spared. Mean dose (Gy): Maximum value of mean dose was found 8.51Gy in 7-bIMRT while it was 6.53Gy in 11-bIMRT technique.    The study indicates that increasing the number of IMRT beams reduces heart’s high-dose volume and improves the quality of treatment plans. It is judicious to use 11-bIMRT technique in left-sided breast irradiation as it produces clinically acceptable mean heart dose.

Sometimes, a patient receives a poor quality medical image from a medical imaging center. Which the doctor orders to re-image with a drug contrast media agent. At this time, practical action is challenging to provide a proper image. Cobalt oxide nanoparticles show different activities based on different sizes and shapes. Objectives of this project is achievement a critical size of cobalt oxide nanoparticles between 5 to 10 nanometers for easy circulation in the blood and   Investigation of the effect of cobalt oxide nanoparticles on the quality of CT from laboratory mice(Mus musculus).

In this study, the coupling method was used to prepare the cobalt oxide nanoparticles. Co3O4 nanoparticle coatings are used for this purpose. They were investigated through the Fourier-transform infrared (FTIR) analysis, X-rays diffraction (XRD). In order to investigate the efficacy of cobalt oxide nanoparticles, we injected a suspension into the Mus musculus, and then the computerized tomography (CT) scans were taken before and after injection of the nanoparticles. Then, quantity evaluation was performed using the calculating the average local contrast media of the whole image.

The average size of cobalt oxide nanoparticles was obtained about 5.8 nm, which is an appropriate size in the nanometer scale. After injecting of cobalt oxide nanoparticles into the mice and then CT scan imaging, we have obtained a better clarity.

Cobalt oxide nanoparticles behave well for use as a pharmacological contrast media agent in CT scan imaging.

Cone-beam computed tomography is used for specialized imaging of dental and maxillofacial structures. CBCTs capabilities and facilities for dental and maxillofacial imaging have resulted in their increasing clinical use. Although the dose of CBCT tests is low, its widespread use increases the cumulative dose. This study was conducted to evaluate head and neck effective dose and image quality in different organs for various exposure techniques in CBCT imaging.

This study was performed on various CBCT imaging examinations. Head and neck parts of anthropomorphic male Rando® Alderson Phantom and thermoluminescent dosimeters were used for organ dosimetry. Contrast to noise ratio and signal to noise ratio were evaluated for image quality assessments. For this purpose, the region of the tooth and soft tissue images were randomly used as the basis.

Mean effective dose for face and paranasal sinuses imaging in three modes (  standard, low-dose, ultra-low dose), temporomandibular imaging in two modes(standard & low dose), and dental imaging in implant and endo imaging modes was equal to 382.17, 193.97, 79.96, 262.6, 135.67, 53.93, 682.83, 335.75, 184.18, and 234.57 μSv, respectively.Signal -to -noise ratio (SNR) for the above-mentioned procedures was equal to 6.04, 5.73, 3.71, 6.3, 6.00, 4.08, 14.2, 12.3, 7.51, and 6.97, respectively.

The present study showed, when low dose and ultra-low-dose modes are chosen, the patient's dose will be severely reduced in most CBCT procedures. Contrast-to-noise ratio (CNR) and SNR will diminish too, but they are sufficient for some diagnostic purposes.

Medical physicists [MP] employed in radiation medicine are health professionals [1, 2] and are responsible for the radiation protection of the patient, staff, and the public. IAEA has prescribed minimum educational and training requirements for being clinically qualified medical physicists [CQMP], [3]. As the application of ionizing radiation is increasing in the diagnosis of various ailments and treatment mostly in radiation oncology, radiology & interventional radiology, and nuclear medicine across the globe, more and more MPs are required to take care of rising demand [4]. In the Asia Oceania region, the rapidly growing health care system requires an increasing number of MPs and many countries in this region have started masters in medical physics [MMP] program. The quality of the MMP program and the competency of MPs produced by the institutes/universities imparting the education and training needs to be of the required standard and requirement. The aim of present study was to access the current status of medical physics education and workforce in the Asia Oceania Federation of Organisations for Medical Physics [AFOMP] region.
To access the status of medical physics education in the AFOMP region data is collected from 21 countries and national medical physics organizations [NMO] of Asia Oceania region regarding the MMP education program, intake capacity, and certification, registration.
It is observed that 105 institutes in the AFOMP region are conducting the MMP program with a total annual capacity of about 800 students. Further, we observed that in 9 countries the MMP programs are accredited, and 11 countries have MP certification boards. From the present analysis, it was observed that the number of medical physicist in AFOMP NMO varies from 0.56 to 20.0 MP per million population.
To meet increasing needs of P, more MPE programs recommended.

In radiation treatment of stage one seminoma (SOS) induced secondary cancer in organs at risk (OARs), is late toxicity of major concern. This study aimed to compare the secondary cancer risk in radiotherapy of SOS in two-dimensional conventional (2D) radiation therapy and three-dimensional conformal radiation therapy (3DCRT). CT scan images of 10 patients with SOS were used to design 2D conventional and 3D conformal treatment plans using 25 Gy in 20 sessions. The life attributable risk (LAR) of the liver, stomach, and colon were calculated using the organ equivalent dose (OED) model for organs in the radiation field and the Biologic Effects of Ionizing Radiation VII (BEIR VII) model for organs out of the field. LAR of OARs in radiation fields such as the liver and stomach were obtained 40% higher in the 2D treatment than in the 3D treatment, while as for the colon, it was 17% lower in the 2D treatment than in the 3D treatment. The LAR values of kidneys located outside the radiation field in the 2D treatment were calculated at 0.04%. Increasing the prescribed dose (25 vs. 20) as well as the number of treatment sessions (20 vs. 10) resulted in increase in the LAR of the liver, stomach, and colon. Therefore, estimating the cancer risk of critical organs exposed to radiation through examining the effects of dose fractionation and prescribed doses can be used in optimizing of the treatment plan for seminoma, selecting a better treatment method by oncologists, and patient follow-up.

In this study, the ultrasound-tissue interactions to obtain the resulting treatment thermal plans of high-intensity focused ultrasound (HIFU) are simulated.
The simulations were performed for three layers of skin, fat, and muscle using Comsol software (version 5.3). The acoustic pressure field was calculated using the Westervelt equation and was coupled with Pennes thermal transfer equation to obtain thermal distribution. The pressure field was calculated and compared in two linear and non-linear models.
By increasing the input sound intensity, the non-linear behavior becomes more pronounced and higher harmonics of the fundamental sound have appeared and increased the pressure, and temperature at the focal point. At input intensities of 1.5, 2, 5, 8, 10, 20, and 30 W/cm2, the maximum acoustic pressure in the non-linear model compared to the linear model was 10, 11, 15, 22, 40, 47, 65, and 85%, respectively. The maximum temperature in the non-linear model increased by 9, 10, 12, 20, 22, 24, 31, and 45% compared to the linear model. Model results were validated with experimental results with a 95% correlation coefficient. The results of the input intensity 1.5, 2 and 5 W/cm2 were acceptable (p<0.05) and from input sound intensity 8 W/cm2 to above, there was a significant difference between the data (p<0.05). Also, maximum pressure and maximum temperature in the non-linear model are 20% more than in the linear model.
In the non-linear propagation model, the resulting thermal pattern changed significantly with the change of the input sound intensity.

Statistical process control (SPC) is a handy and powerful tool for monitoring quality assurance (QA) programs in radiotherapy. This study explains the institutional experience in monitoring weekly output constancy QA and patient-specific quality assurance (PSQA) using SPC tools.

Prospective monitoring of output constancy has been demonstrated by the simultaneous usage of Shewhart's I-MR charts and time-weighted control charts. PSQA results were retrospectively analysed in a combined γ and dose volume histogram (DVH) based analysis using control charts and process capability indices. A PSQA analysis method has been illustrated in which the site-specific action limits (AL) and control limits (CL) for γ and DVH based analysis were obtained using SPC.               

The simultaneous use of different control charts indicated a systematic error in the output constancy of Linac as successive measurement points fell above the CL. The reason for failure was found and process was monitored further. The obtained AL and CL for γ and DVH based analysis were used to decide pass or fail criteria in PSQA. Among the analysed treatment plans, fourteen plans of different treatment sites failed the PSQA analysis. Cause-and-effect analysis of these failed treatment plans in PSQA pointed out six primary potential sources of errors in the results.

SPC tools can be adopted among institutions for consistent and comparable QA programs. If the QA process monitored using SPC falls outside the CL, cause-and-effect diagrams can be used to extract all possible contributing factors that lead to such a process state.