Background/Objective: The dose distribution is affected by tissue inhomogeneities. The objective of this study was a dosimetric evaluation of the potential corrective role of computed tomography (CT) data in radiotherapy treatment planning (RTP) for various anatomical sites of the body (head and neck, abdominopelvis and thorax), separately.Patients and Methods: Fifty-four cases of head and neck, pelvis, abdomen and breast cancers were included in this study. All of the patients were scanned with the same CT machine.Each case was planned with and without CT-based density correction by a two-dimensional ALFARD RTP system. Analyses of dosimetric parameters were performed for with and without inhomogeneity corrections based on the effective path length method. Dosimetric parameters were dose uniformity (Te), the average (Davg), minimum (Dmin) and maximum (Dmax) doses for both the planning target volumes and organs at risk. These parameters with and without CT-based density correction were compared in the head and neck, abdominopelvic and thoracic regions, separately.Results: The mean difference of Te and Davg between these two methods was statistically significant in the thoracic region (7.13±5.55; p=0.001 for Te and 4.65±6.59; p=0.04 for Davg).Measurements of Te, Davg, Dmin and Dmax in the head and neck and abdominopelvic regions showed no statistically significant differences between the two methods (all p values ³0.05).Conclusion: In some parts of the body, if the CT correction for density variation was not applied, the dose deviations could be out of the tolerance limits defined by the standards for tumors and normal tissues.

Introduction: To determine radiotherapy accuracy and prevent treatment errors, quality assurance is crucial during the planning phase of radiation therapy. Therefore, the goal of this study was to create criteria for the routine quality control assessment of radiation treatment planning systems TPS to assess their effectiveness and accuracy. Material and Methods: In this study, we used a Prowess Panther treatment planning system TPS (version 5. 51), a Siemens model Somatom Confidence computed tomography simulator, an anthropomorphic Alderson-Rando phantom, and a density phantom made from a CTDI head phantom by inserting plugs that mimicked human tissue. The TPS features include hardware, transmitted CT images (anatomical information), and key software operations,however, in this investigation, we focused exclusively on the tests involving anatomical information. Results: The Prowess Panther RTPS version 5. 51 workstation consistently met the requisite quality where all results of the radiation treatment planning systems (Prowess Panther RTPS) anatomical information tests were satisfactory and acceptable. Conclusion: By averting several radiation-related events, the recommendations for TPS CT image quality control testing made in this study will assist to increase the safety and effectiveness of cancer radiotherapy.

Manual fusion (MF) is a readily available image registration technique that does not require matching algorithms. The operator performs rigid-body transformations interactively. The precision of MF (as implemented on the Philips Pinnacle treatment planning system) was required for cranial CT-MR images used in radiotherapy planning for typical centrally located planning target volumes (PTVs). Materials and methods: A multi-stage MF procedure was developed which 11 observers followed to match the head contour, bones, soft tissues and contoured structures for 5 patient image-sets. Registration parameters were calculated by solving the transformation matrix following a consistent order of translations (T) and rotations (R). The mean position of centre of each PTV averaged over all observers was used as the reference. The effect of misregistration on the PTV co-ordinates and the volume increase resulting from application of a margin for registration uncertainty were calculated. Results: Mean intra- and inter-observer T/R SDs were 0.5mm/0.4 and 1.1mm/1.0, respectively. Mean intra- and inter-observer registration error (3D distance of each PTV centre from the mean position for all observers) was 0.7  0.3 mm (1 SD) and 1.6  0.7 mm respectively, the latter reducing to 1.4  0.6 mm excluding the 3 least experienced operators. A subsequent 2 mm margin for misregistration on average increased the PTV volume by 27%. Conclusion: Moderately trained operators produced clinically acceptable results while experienced operators improved the precision. MF still has an important role in the registration of cranial CT and MR images for radiotherapy planning especially for under-resourced centers.

Background: External beam radiotherapy (EBRT) is mainstay of treatment in patients with locally advanced cervical carcinoma (LACC). Three dimensional conformal radiotherapy (3DCRT) and intensity modulated radiotherapy (IMRT) are mainly used in EBRT. However which one is superior is still controversial. Materials and Methods: Forty patients of LACC treated with IMRT were selected for this study.3DCRT plans were also created for all the patients.3DCRT and IMRT plans were compared on the basis of planning target volume (PTV) coverage, dose to normal organs, homogeneity index (HI) and conformity index (CI95%).Results: In both the techniques 99% of PTV was covered with more than 96% of prescribed dose (PD). D15, D35 and D50 (Dose to 15%, 35% and 50% volume respectively) for bladder was reduced by 2.09%, 14.623% and 32.57% and for the rectum it was reduced by 7.46%, 23.82% and 43.68% in IMRT compared to 3DCRT. V45 (volume receiving 45 Gy) in case of bowel were found to be much less in IMRT in comparison to 3DCRT. Insignificant difference found between doses to femoral heads in IMRT and 3DCRT. The CI95% in IMRT plans was found much better than that in 3DCRT whereas HI in both the techniques were found almost same.Conclusion: IMRT significantly reduced the irradiated volume of OAR and improved dose conformity in the PTV compared to that by 3DCRT. So, it can be concluded that IMRT should be chosen as preferred technique for the EBRT of LACC with proper immobilizing devices and imaging.

Introduction: The current study aimed to compare linear accelerator-based three-dimensional conformal radiotherapy (Linac-3DCRT) technique with different techniques of the Radixact-X9 for the treatment of craniospinal irradiation (CSI). Material and Methods: Following a retrospective design, 22 CSI patients (Medulloblastoma) treated with Linac-3DCRT using the Novalis-Tx unit were selected for analysis. For each patient plan, additional sets of plans were generated using Helical, Direct-3DCRT, and Direct-intensity-modulated radiotherapy (Direct-IMRT) techniques of the Radixact-X9 unit. The dose prescription for brain planning target volume (brain PTV) and spine PTV were 36 Gy in 20 fractions and kept the same for all techniques. planning time, patient setup time, homogeneity index (HI), and different dose-volume parameters for both PTV and organs at risk (OARs) were evaluated for comparison. Results: The Radixact-X9-Helical technique can generate a plan in a more comparable and better manner in respect of maximum and minimum doses for most of the organs. The Radixact-X9-Helical technique resulted in better PTV homogeneity in comparison with Linac-3DCRT, Radixact-X9-Direct-3DCRT, and Radixact-X9-Direct-IMRT. The values of HI were 3. 57±, 0. 77, 17. 37±, 1. 44, 8. 15±, 1. 02, and 8. 62±, 0. 98, respectively. Conclusion: Not only administration of the Radixact-X9-Helical treatment technique is easier, but also can generate a better homogeneous plan than other treatment techniques like 3DCRT and IMRT regarding different parameters for comparisons like dose-volume received by OARs, patient setup time, move isocenter, and many more. So it can be an integral part of the radiotherapy department, according to their clinical needs like shorter treatment time with good sparing of critical OARs

Along with chemotherapy and surgery, radiotherapy remains as an important modality in tumor treatment, as it is used to treat approximately 50% of all patients with localized cancer [1-3]. However, the use of radiotherapy inevitably leads to exposing the organs/ tissues that are entirely or partially excluded from the treatment volume [4]. Therefore, out-of-field regions receive dose values due to secondary radiation sources, including scattered radiation from collimators and beam modifiers...