فهرست مطالب mohsen saeb

Treatment planning target volume (PTV) motion in prostate cancer tomotherapy is an important challenge in treatment planning. This study aimed to evaluate PTV margins for prostate cancer tomotherapy.

From 2021 to 2023, 20 patients with prostate cancer underwent tomotherapy. Before each treatment session, the MVCT image was taken from the patient, and the patient's settings were made using pelvic bone markers and tattoos. Before treatment, prostate volume was measured by ultrasound. Bladder volume was measured in MVCT images and compared with CTSim images. PTV displacements were measured and the required margin for 95% PTV dose was determined using the average prostate displacement. Correlation coefficients between bladder volume, prostate volume, and PTV displacement were calculated.

This study analyzed a total of 497 MVCT and 20 CT images. Anisotropic PTV margins, accounting for random uncertainties, were 14-6.9 mm for PTV1, 11.4-6.2 mm for PTV2, and 5.9-3.5 mm for PTV3 in the anterior-posterior direction, respectively.

This research reveals that a non-uniform PTV margin is needed to compensate for the random uncertainties caused by the movement of the prostate between tomotherapy sessions. Filling of the bladder and diet play a vital role in the displacement of the prostate.

This study aimed to compare the tumor control probability (TCP) and the normal tissue complications probability (NTCP) of three-dimensional adaptive radiation therapy (3D-CRT) and tomotherapy for left pendular breast cancer using radiobiological models.

The current study was conducted on 20 patients with left pendular breast cancer who underwent treatment planning using the treatment planning system for 3D-CRT and tomotherapy. A prescribed dose of 50 Gy was implemented for the planning target volume (PTV) in both 3D-CRT and tomotherapy designs. The Equivalent Uniform Dose (EUD) of the Niemierko model was used to estimate the tumor control probability (TCP) and the normal tissue complications probability (NTCP).

According to the results, the average TCP values for 3D-CRT and tomotherapy plans were 99.07 ± 0.13 and 99.32 ± 0.09, respectively, which did not show a statistically significant difference. The NTCP values for the lung and heart were significantly lower in tomotherapy plans compared to 3D-CRT plans.

From a radiobiological point of view, the results showed that 3D-CRT resulted in a lower NTCP for the ipsilateral lung. In contrast, for TCP calculations, tomotherapy plans showed higher values compared to 3D-CRT plans.

Head and neck cancer (HNC) is among the ten most common cancers worldwide. Due to the complex head and neck anatomy, many organs receive radiation during treatment. The aim of this study is to compare the cochlea dose in two different treatment methods, 3D-CRT (Three-Dimensional Conformal Radiotherapy) and HT (Helical Tomotherapy).

The current study is applied and cross-sectional. 28 patients who had nasopharyngeal cancer and were referred to Seyed al-Shohada Hospital (Omid) for treatment between 2020-2022 and are candidates for treatment with one of the 3D-CRT or HT devices; were included in this study. The treatment plan for each patient was simulated in two devices and then study variables such as maximum and average dose and homogeneity and conformity index were investigated.

Upon comparing the treatment plans of Helical Tomotherapy (HT) and Three-Dimensional Conformal Radiation Therapy (3D-CRT), it was found that the average dose received by organs at risk, such as the cochlea, was significantly lower in the HT method compared to the 3D-CRT method. This indicates a significant difference between the two treatment methods.

Our study on patients with nasopharyngeal cancer revealed that Helical Tomotherapy (HT) treatment led to better target homogeneity and compliance compared to conventional Three-Dimensional Conformal Radiation Therapy (3D-CRT). Additionally, HT was found to reduce the dose delivered to organs at risk (OARs) in comparison to 3D-CRT.

Nasopharyngeal cancer is one of the common head and neck cancers and the main treatment for this type of cancer is radiotherapy. The purpose of this study is to investigate and compare the dose of organs at risk in two adaptive three-dimensional methods (3D-CRT) and helical tomotherapy (HT) in patients with head and neck cancers.

This study is a cross-sectional experimental retrospective study and to conduct this study, CT scan images (Computed Tomography) of 16 patients with early stages of NPC with an average age range of 16-81 years (42.7 ± 16.3) those were randomly selected. The organs at risk and their target volume were contoured and the treatment plan of the patients was done for both HT and 3D-CRT methods. In the end, using a Volume-Dose histogram (DVH), the dosimetry variables of organs at risk and target volume were extracted and compared with each other.

Compared to 3D-CRT, the HT method improved the homogeneity index and concordance index. It also significantly reduced the dose of the studied OARs compared to 3D-CRT, although the dose of some of these organs exceeded the prescribed dose limit.

HT method is a better technique for treating nasopharyngeal cancer patients who are candidates for radiotherapy due to better coverage of the target volume and also, better performance in preserving OARs compared to the 3D-CRT method.

Breast cancer is the most common type of malignancy seen in women globally and the second life-threatening cancer among women after lung cancer. This research aims to compare the dosimetric differences based on two radiotherapy treatment plans for left breast cancer after surgery.

CT scan data from 20 patients who were candidates for radiotherapy diagnosed with left breast cancer were randomly selected and sent to the treatment design software. The target organ (left breast) and organs at risk including lungs, heart, right breast were contoured by the radio-oncologist. The design of three-dimensional conformal radiotherapy (3D-CRT) was designed using two opposite tangential beams, depending on the patient's anatomy, with and without wedge and with energy of 6 MV. The tomotherapy treatment was designed with an energy of 6 MV. Finally, using the dose-volume distribution curve (DVH), the dosimetric variables of the target organ and the organs at risk were extracted and compared with each other.

The three-dimensional conformal radiotherapy method reduced the average dose of the target organ and organs at risk compared to the tomotherapy method. The compliance index and homogeneity index were improved in the tomotherapy method, although the volume coverage of the left lung organ increased at low doses compared to the three-dimensional conformal radiotherapy method.

The tomotherapy method is a more suitable method for treatment than the three-dimensional conformal radiotherapy method as it enhances the target volume coverage and offers a better dose distribution.

This study aimed to evaluate the overall accuracy of the beam commissioning criteria of targeted image‑guided radiation therapy (TiGRT) treatment planning system (TPS) based on the American Association of Physicists in Medicine (AAPM) Task Group Report 119 (TG‑119). The work was performed using 6 MV energy LINAC with a variable dose rate of 200 MU/min which equipped with the high‑quality external TiGRT dynamic multileaf collimator model H. The AAPM TG‑119 intensity‑modulated radiation therapy (IMRT) commissioning tests are composed of two preliminary tests and four clinical test cases. The clinical tests consisted of mock prostate, mock head and neck, C‑shaped target, and multitarget. EDR2 flm was used for evaluating the IMRT plans and point dose measured by a Pinpoint chamber positioned in slab phantom. The flm analysis was done with the Sun Nuclear Corporation patient software. The dose prescription for each fraction was 200 cGy in mock prostate, mock head and neck, C‑shaped target, and multitarget. Dose distributions were analyzed using gamma criteria of 3% and 2% dose difference (DD) and 3 and 2 mm distance to agreement. In all test cases, the gamma criteria for 2%/2 and 3%/3 were found to be 94% and 98%, respectively. Results showed that the average gamma criteria result was in the range of 99.1% to 93% (3%/3, 2%/2) overall test cases. Findings were favorable and in some tests were comparable with the other studies. The dose point values were within the mean values of the range reported by TG‑119. Overall, the TiGRT TPS is needed to apply IMRT technique in radiation therapy centers.

Tumor volume delineation is the most important step in the radiation treatment planning. In this study the impact of PET/CT data on the tumor delineation precision of non-small cell lung cancer (NSCLC) was investigated.
PET/CT images of 20 patients with primary NSCLC were obtained and imported to the treatment planning system for image fusion, contouring and radiation treatment planning. For each patient two separate gross tumor volumes were delineated based on CT and PET/CT images as GTVCT and GTVPET/CT, respectively. In addition, three different indices including conformity index (CI), geographic miss index (GMI) and geographic include index (GII) were calculated to quantify the match and mismatches degree between derived volumes. Then, for each patient an appropriate 3D conformal treatment plan was made based on the PTVCT and then these plans were applied on the PTVPET/CT. Afterwards, the dose coverage of PTVPET/CT was estimated through several dosimetric parameters.
The GTVPET/CT was larger than GTVCT for majority of cases. The 25% exceeded volumetric alterations were observed in 8 of all cases (40%). Mean values of CI, GMI and GII were 0.43, 0.42 and 0.34, respectively. Also, dosimetric parameters indicated inadequate dose coverage of PTVPET/CT in CT-based RT plans for most of the patients.
Incorporating PET data into tumor delineation process had a great potential to improve the quality of radiation treatment planning for NSCLC.

Performing audits play an important role in quality assurance program in radiation oncology. Among different algorithms, TiGRT is one of the common application software for dose calculation. This study aimed to clinical implications of TiGRT algorithm to measure dose and compared to calculated dose delivered to the patients for a variety of cases, with and without the presence of inhomogeneities and beam modifiers.

Nonhomogeneous phantom as quality dose verification phantom, Farmer ionization chambers, and PC‑electrometer (Sun Nuclear, USA) as a reference class electrometer was employed throughout the audit in linear accelerators 6 and 18 MV energies (Siemens ONCOR Impression Plus, Germany). Seven test cases were performed using semi CIRS phantom.

In homogeneous regions and simple plans for both energies, there was a good agreement between measured and treatment planning system calculated dose. Their relative error was found to be between 0.8% and 3% which is acceptable for audit, but in nonhomogeneous organs, such as lung, a few errors were observed. In complex treatment plans, when wedge or shield in the way of energy is used, the error was in the accepted criteria. In complex beam plans, the difference between measured and calculated dose was found to be 2%–3%. All differences were obtained between 0.4% and 1%.

A good consistency was observed for the same type of energy in the homogeneous and nonhomogeneous phantom for the three‑dimensional conformal field with a wedge, shield, asymmetric using the TiGRT treatment planning software in studied center. The results revealed that the national status of TPS calculations and dose delivery for 3D conformal radiotherapy was globally within acceptable standards with no major causes for concern.

Receiving exact dose by the patients is vital in radiotherapy. The TECDOC1583 protocol is used to achieve this goal. This study aimed to evaluate several levels and steps of treatment planning, in order to calculate the precise dose received by the patient, and to compare it with actual results.
The distribution of doses for single, multiple and complicated multiple field beams of treatment planning were calculated using TiGRT. Results were compared with the measured results of anthropomorphic phantom in different phases.
Findings: According to the TECDOC1583 protocol, all the results were accepted; but in the fifth level of the test, percent of error in the lung was 4.3% which made a 0.3% of discrepancy. In the sixth level of the test, the percent of error in soft tissue was 5.7% with about 2.7% of discrepancy.
Due to the lack of electronic density in lung tissue, a treatment planning software with higher accuracy is needed for evaluations. Our findings showed that technicians’ knowledge regarding to the application of treatment planning software is essential in this regard. Since the produced error would not be acceptable in this area, and the accuracy of the treatment planning software is no more confident, so working based on correct algorithm of treatment planning software should be checked and system restarting and commissioning must be re-evaluated periodically.