One major adverse effect of prostate radiotherapy is associated with the rectum. The SpaceOAR system has been developed to address this problem, as it enables treatment planning with a reduced dose to the rectum. This study aimed to evaluate and compare the treatment plans between three-dimensional conformal radiotherapy (3D-CRT) and volumetric modulated arc therapy (VMAT) for prostate cancer using the SpaceOAR system. Thirty-five patients treated with prostate cancer radiation using the SpaceOAR system received a total radiation dose of 60 Gy/20 fractions. The dose constraints and robustness of the plan for VMAT and 3D-CRT were compared. For 3D-CRT, 6-field conformal method and 2-arc conformal method were created and compared in 3 treatment plans together with VMAT. The dose-constraint evaluation was performed using the planning target volume (PTV), rectum (mean dose), bladder (mean dose), and femoral head (mean dose). One issue associated with prostate radiotherapy is the physiological movement of the target prostate gland, which reduces the accuracy of irradiation. The prostate moves several millimeters during irradiation due to physiological movements, and there are reports of a decrease in the PTV index due to this effect. This has a significant impact on the cure rate of prostate cancer. A comparative study of the 3 irradiation methods was conducted to investigate this issue. Each study item was analyzed using the Friedman test to determine the significance of the 3 irradiation methods. Our analysis showed that the dose constraint was statistically significant for VMAT, but 3D-CRT was also sufficient in achieving dose constraints. The hydrogel spacer reduced the rectal dose and improved the dose-constrained fulfillment rate in VMAT and 3D-CRT. In a study of prostate motion during irradiation, 3D-CRT, a robust plan, was superior in the PTV mean evaluation over VMAT, where the multileaf collimator moved in fine increments. VMAT is currently the standard treatment for prostate cancer; however, with the introduction of the SpaceOAR system using hydrogel spacers, 3D-CRT may also be a viable option for prostate cancer treatment.

To assess the dosimetric characteristics of HyperArc (HA), noncoplanar VMAT (NC-plan), and coplanar VMAT (HL3arc) in hippocampal-sparing whole-brain radiotherapy (WBRT). Twenty patients undergoing WBRT at our Hospital from June 2021 to March 2023 were selected. The dose parameters of organs at risk (OARs) were evaluated for all three groups, including D, D, and D of hippocampus, D to the lens, eyes, optic nerves, and chiasm, D to the scalp and upper neck, and the dose volume parameters V, V, V, V for the upper neck. The D, V, D, HI, CI, GI for PTV, as well as planning time, and beam-on time. HA had the lowest hippocampal D and D. HA's scalp D was lower than HL3arc (p = 0.007). HA's upper neck region D and V(cm) were significantly higher than NC-VMAT and HL3arc. For PTV, HA's D and V were higher than NC-VMAT and HL3arc (p < 0.05). HA exhibited a significant advantage in terms of HI, CI and GI. The average planning times were 84.67, 17.30, and 20.40 minutes. Among the three treatment approaches, HA demonstrated the lowest bilateral hippocampal doses, but it exhibited the highest average dose and low-dose volume in the upper neck region, with the longest planning optimization process.

We evaluated the effects of different aperture shape controller (ASC) settings on the dose distribution and delivery efficiency of lung stereotactic body radiotherapy (SBRT) using volumetric modulated arc therapy (VMAT) with a 10 MV flattening filter-free (FFF) beam. Ten lung SBRT cases with breath-holding were retrospectively analyzed by comparing plans with no-ASC and those with 5 ASC settings (very low, low, moderate, high, and very high). The gross tumor volume (GTV) coverage: D (minimum dose to 98% of the volume), target conformity index (CI), gradient index (GI), D (dose maximum at 2cm from the planning target volume), lung dose, monitor unit (MU), modulated complexity score for VMAT (MCSv), and delivery time were evaluated. Compared with the no-ASC setting, there were no significant differences in GTV coverage, GI, or D in the different ASC settings. A very high ASC setting resulted in a slight increase in the mean lung dose metrics. On average, MU and delivery times were significantly reduced by approximately 200 MU and 5.0 s with very high ASC settings compared to the no-ASC setting. Plan complexity decreased as the ASC increased, with the very high ASC setting showing the highest MCSv values. This study suggests that the very high ASC setting may improve the delivery efficiency for lung SBRT using VMAT with the 10 MV FFF beam under breath-holding while maintaining comparable dose distributions and target coverage.

One of the reasons for planning heterogeneity is lack of enough experience and recommendations on the quality of Linac-based stereotactic radiosurgery (SRS). In this study, our goal is to investigate the impact of planner's experience on the quality of Linac-based SRS plans for brain metastases (BMs) with varying levels of complexity. Specifically, to assess the impact of experience on the outcome of an automated noncoplanar treatment planning. A cohort of 120 patients with intracranial SRS plans, with a total of 633 BMs, was examined using VMAT delivery calculated with an available automated plan delivery system. Four planners with different levels of experience, ranging from under 1 year to over 5 years (Expert planner) of SRS planning, generated treatment plans. Dosimetric parameters and plan quality metrics were evaluated including: conformality index, homogeneity index, modulation factor, R, total volume of brain receiving 12Gy, 6Gy, and 3Gy (V, V, V) were assessed for each plan and compared with plan which was created by an expert planner with the highest planning experience. Experienced planners consistently produced acceptable plans, while less experienced one required revisions. Single BM cases showed minimal deviations in dosimetric parameters (under 10%) irrespective of planner experience. However, as the number and complexity of BMs increased, differences in plan quality became more pronounced. Moreover, expert planner's plans consistently outperformed others in terms of organs at risk sparing. This difference was particularly pronounced for cases involving the volume of healthy brain tissue. Our study underscores the critical role of planner's experience in the quality of Linac-based SRS plans using an automated planning. By standardizing and enhancing the planning process, the study aims to improve the quality of care for patients with multiple BMs, contributing to more efficient and effective treatments in the field of SRS.

To compare proton plans (IMPT) to VMAT plans and intercompare proton plans using 3 different spot sizes with robustness: cyclotron-generated proton beams (CPB) (σ: 2.7-7.0 mm), linear accelerator proton beams (LPB) (σ: 2.9-5.5 mm), and linear accelerator proton mini beams (LPMB) (σ: 0.9-3.9 mm) for the treatment of early-stage lung cancer. Twenty-two lesions from a total of twenty patients with early-stage lung cancer, originally treated with SBRT, were replanned using CPBs, LPBs, LPMBs, and VMAT using the same treatment planning system and dose calculation algorithm. The average intensity projected CTs (AIP-CT) were used for planning and 3D robust optimization was used for all proton plans. Conformity index (CI), homogeneity index (HI), R, lung V , and mean lung dose were compared among all proton plan types and with VMAT plans. Set-up uncertainties of ±5 mm and ±3.5% range uncertainty were included in the IMPT robust optimization and evaluation, using V > 98% of the ITV. The Wilcoxon signed-rank test was used to evaluate statistical differences between VMAT plans and all proton plan types. When compared to VMAT plans, all proton plans generally show improvement in CI, HI, Lung V , Mean lung dose, and R. The LPMB plans showed the most improvement from VMAT plans. Comparison between CPB and linear accelerator proton plans showed statistical significance (p < 0.05). R and mean lung dose for the CPB, LPB and LPMB plans were 3.6 ± 0.9, 3.1 ± 0.8 and 2.6 ± 0.6; 2.2 ± 1.1 Gy, 1.9 ± 1 Gy and 1.6 ± 0.9 Gy, respectively (p < 0.05). The mean R and mean lung dose from the VMAT plans were 4.1 ± 0.4 and 3.8 ± 2 Gy, respectively. The V  (%) of lung and mean lung dose were improved across all proton plans when compared with those of VMAT plans. When evaluated for robustness in the worst-case scenario at V of the ITV > 98%, average ITV coverage of 98.6 ± 0.3%, 98.6 ± 0.6%, and 98.9 ± 0.6% were achieved for CPB plans, LPB plans, and LPMB plans, respectively. With decreased spot size, the LPB and LPMB plans are excellent alternatives to VMAT and cyclotron-generated proton plans with reduced dose to normal tissue and improved plan quality for early-stage lung cancer treatments.

The purpose of this study is to assess the influence of Planning Target Volume (PTV) on the quality of automatic planned O-Ring Halcyon linac stereotactic body radiation therapy (SBRT) plans of pelvic lymph nodes (LN) and lung metastases and to evaluate an absolute PTV volume threshold as a plan quality prediction criterion. A total of 21 pelvic LN and 18 lung clinical treatment plans were replanned for Halcyon with unattended autoplanning. The prescription dose range was 26-40 Gy for LN and between 39-54 Gy for the lung in the mean 3 fractions. The mean/median PTV was 4.0/ 3.6 cm for LN and 4.9/ 4.3 cm for the lung. The criteria for the plan quality evaluation consisted of using dose metrics for conformity, spillage, and coverage and dose limits on healthy tissue assessment. A statistical study was performed based on systematic Mann-Whitney U test and cluster analysis to evaluate a PTV volume predictor threshold of plan quality. 95% (n = 20) LN and 100% (n = 18) lung plans met all tolerance criteria. For both cohorts of plans, a PTV threshold was determined, indicating a reduction of particular dose indices when below this threshold. Low risk of toxicity in healthy tissues was predicted. A PTV threshold of 4.0 cm was estimated as quality criteria in both cohorts of plans. The results of our study demonstrated the promising performance of Halcyon for pelvic and lung SBRT for small tumors, although plan-specific QA is required to verify machine performance during plan delivery.

In radiotherapy treatment planning systems, modelling of superficial dose may be aided by a body contour that is, by default, placed at the outermost air-tissue interface. Here we investigate the accuracy of superficial dose calculated using either the default body contour (DBC) or an extended body contour (EBC) compared to radiochromic film measurements made on a slab phantom and an anthropomorphic phantom.

This study presents a patient with a PET-CT detected residual lacrimal sac tumor who was treated with intensity modulated proton therapy (IMPT) and concurrent chemotherapy. The patient a 49-year-old male diagnosed with squamous cell carcinoma of the left lacrimal sac had under-went endoscopic surgery. Postoperative PET-CT implied tumor residual in the left lacrimal sac. Given the tumor's proximity to optic organs, IMPT was employed to provide optimal dose painting. The precise delineation of the target volumes using multimodal imaging modalities (CT, MRI, and PET-CT), coupled with daily cone-beam CT technology for accurate positioning during radiotherapy contributed to an adequate dose coverage of the target. In comparison to helical tomotherapy (TOMO) and volumetric modulated arc therapy (VMAT), IMPT reduces doses to most ocular structures. With a follow-up period of 21 months after IMPT, the patient exhibited no evidence of disease recurrence and experienced only mild toxicity. This report highlights the critical role of multimodal imaging in diagnosis and radiotherapy planning. Furthermore, a literature review of proton therapy for malignant lacrimal sac tumors reveals that the scarcity of reports and emphasizes the importance of this case as a significant contribution to medical literature. This highlights the potential benefits of optimal tumor control and reducing toxicities by the integration of multimodal imaging and IMPT.

Uganda's only radiotherapy center is a very busy facility treating about 210 patients daily on three linear accelerators making it sometimes hard to have machine time for pretreatment QAs. This study was aimed at validating an independent calculation software, ClearCalc (ICS) for second checks of the treatment planning system (TPS) calculations. The validation of ICS started with simple phantom test plans consisting of square, irregular, open and wedged fields designed in the TPS and measured in phantoms. Doses and monitor units (MUs) calculated by ICS were compared with TPS calculated doses and with measured doses. ICS was then validated on clinically approved treatment plans: comparison with TPS calculations and with pretreatment QA measurements performed with electronic portal imaging devices (EPIDs) and analyzed using Gamma passing criteria of 3%/3 mm and 3%/2 mm. Results for test plans were within the passing level of 3.0% except for 2 outliers (-3.1% and 3.1%). As for the clinically approved treatment plans, they show good agreement between MUs (0.2 ± 1.8%), reference point doses (0.2 ±1.5%) and mean PTV doses (0.5 ± 1.4%). ICS calculated (3D) mean gamma pass rates were 98.1±1.6% and 98.4±1.0% for 3%/2 mm and 3%/3 mm criteria. No correlation was seen between gamma analysis results from ICS and EPID. This study validated ClearCalc on phantom and clinically approved plans. The result show that ICS based patients specific QA is quick, promising and potentially allows significant time saving that can be utilized for patient treatments.

Sweat gland cancers, particularly eccrine sweat gland carcinomas, are rare and challenging to treat due to their aggressive nature and inconspicuous clinical presentation. Aggressive digital papillary adenocarcinoma, a rare subtype, frequently presents with delays in diagnosis, increasing the risk of metastasis and recurrence. Surgical excision remains the standard treatment, but the role of postoperative radiation therapy is not well-established due to the paucity of data. This case study explores the use of radiotherapy in treating a 50-year-old female with digital papillary adenocarcinoma of the great toe. A custom three-dimensional (3D) printed bolus was utilized to improve dose distribution and reproducibility in radiation treatment using Volumetric Modulated Arc Therapy (VMAT). The comparative analysis of VMAT and 3D conformal radiation plans demonstrated superior target coverage, dose homogeneity, and reduced exposure to adjacent healthy tissue with VMAT. The findings contribute valuable insight into the use of 3D-printed bolus and advanced radiotherapy techniques in the management of rare sweat gland cancers, particularly in complex anatomical regions like the toe.

Most of conventional 2-dimensional (2D) methods verify dose of multiple targets separately one-by-one for Single-isocenter Multiple-target (SIMT) brain plans, which are inefficient and sub-optimal. This study presented a practical method to verify the dose of 2 targets simultaneously for improved efficiency and accuracy. Fifteen Stereotactic Radiation Therapy (SRT) and sixteen Stereotactic Radiosurgery (SRS) plans were used for this study. Each plan has 2 targets coincide with a plane through the plan isocenter. All plans were created in the Eclipse Treatment Planning System (TPS) using a 6 MV flattening filter free photon beam. A 2D detector array, myQA SRS was used for measurements. It has a spatial resolution of 0.4 mm and an active area of 120 × 140 mm. It can be rotated along the longitudinal axis with a cylindrical phantom with one-degree precision. All plans were delivered with the detector array centered at the plan isocenter and rotated to intersect 2 targets. Six plans with target separations less than 70 mm were crosschecked with the SRS MapCHECK, which has an active area of 77 × 77 mm. The measured 2D dose distributions were compared with those calculated from the TPS. Gamma-index analysis was performed using 3%/1 mm criteria and a 10% dose threshold. For all 31 SIMT brain plans measured with myQA SRS, the average and standard deviation of the gamma-passing rate was (96.8 ± 2.2)%. For 15 SRT plans and 16 SRS plans, that was (96.6 ± 2.4)% and (97.0 ± 2.1)%, respectively. For 6 plans crosschecked, the average gamma-passing rates were 96.8% vs. 94.8% with myQA SRS and SRS MapCHECK, respectively. A practical method to verify the dose of 2 targets simultaneously was demonstrated. It offers an efficient way for pretreatment verification of SIMT SRT and SRS plans with improved accuracy.

This study was conducted to evaluate the use of 4-dimensional (4D) maximum intensity projection (4D-MIP) to compensate for the disadvantages of average intensity projection (AIP), which is used to determine the internal target volume (ITV) in lung tumors. A respiratory motion phantom with a simulated tumor was imaged using 4D computed tomography (4D-CT). AIP and 4D-MIP were generated based on 10 phases of 4D-CT, followed by contouring of the ITV and ITV; these were compared with the ITV contoured in 10 phases of 4D-CT (ITV). Additionally, the profile curves of the ITV and ITV were obtained, and the full width at half maximum (FWHM) was measured. There was no significant difference between the ITV and ITV; however, the ITV demonstrated a lower value. The FWHM values of the ITV were smaller than those of ITV owing to decreased CT values in the superior-inferior margin. 4D-MIP may contribute to improving the consistency of the ITV delineation.

Axillary dose restriction (ADR) is rarely implemented in breast cancer radiotherapy by radiation oncologists to minimize exposure to organs at risk (OARs), particularly the axilla. This prospective randomized controlled study aims to evaluate the efficacy of ADR in improving plan quality (PQ) and its impact on acute radiation dermatitis (ARD) in breast cancer radiotherapy. The study recruited breast cancer patients who required postoperative radiotherapy but did not have an indication for axillary irradiation. Delineation and dosimetric assessment of the axilla (Axilla Levels I-III and Axillary Cavity) were performed in all cases, with ADR implemented randomly. ADR involved restricting the mean axilla dose to 40-45 Gy during radiotherapy. The outcomes assessed included the ARD grades (both overall and axillary) and dose-volume parameters of PQ including skin V35. The study enrolled 87 patients, who were randomly divided into two groups: Group I (50 patients) received ADR, while Group C (37 patients) did not. ADR was found to be significantly associated with reduced exposure doses to the axilla and ipsilateral lung, specifically in patients with modified radical mastectomy (MRM). Results of other PQ parameters, such as D95, V93, V95, V100, V107 for the planning target volume (PTV), V30, Dmean for the heart, Dmax for the spinal cord, and V5 for the ipsilateral lung, demonstrated potential benefits in alleviating doses to these OARs while maintaining optimized PQ, although these results were not statistically significant. However, no statistically significant correlation between ADR and severe ARD (≥ Grade 2) or skin V35 was established, either in the total patient population or in subgroups. Additionally, a multivariable logistic regression for severe ARD was conducted, with ADR and skin V35 included as predictive factors. Only older age was found to be significantly associated with severe ARD. Implementing ADR in breast cancer radiotherapy not only protects the axilla and ipsilateral lung but also maintains optimized PQ, specifically in MRM patients, though it shows no evidence of alleviating ARD. Adopting ADR may be considered a valuable option in breast cancer radiotherapy.

This article aims to compare the dosimetric performance between knowledge-based plan (KBP) libraries with and without trade-off (TO) exploration using multicriterial optimization (MCO) for tongue cancer patients. The trade-off optimized library (KBP_MCO) contains a minimal number of constituent plans, whereas two nontrade-off optimized libraries contain a minimal and a large number of treatment plans, respectively. Three KBP libraries were created: KBP_100 and KBP_20, each comprising of 100 and 20 manually optimized plans, respectively. Additionally, another KBP library (KBP_MCO_20) was created by reoptimizing the constituent plans from KBP_20 using MCO techniques. A total of 70 tongue plans were validated through these libraries. Validation plans were evaluated for PTV and organ at risk (OAR) doses. Greenhouse-Geisser analysis (ANOVA) and the Bonferroni procedure (t-test) were used for statistical evaluation. The mean PTVD95% for KBP_100, KBP_20, and KBP_MCO_20 was 98.4% ± 0.3%, 98.9% ± 0.2%, and 98.7% ± 0.2%, respectively. The statistical significance of PTVD95% for the 3 possible combinations-KBP_100 vs KBP_20, KBP_100 vs KBP_MCO_20, and KBP_20 vs KBP_MCO_20 were statistically significant with p < 0.001. Spinal cord doses for KBP_100, KBP_20, and KBP_MCO_20 were 29.6 ± 1.8 Gy, 31.2 ± 2.5 Gy, and 26.8 ± 1.9 Gy, respectively, with p(KBP_100 vs KBP_20) = 0.14, p(KBP_100 vs KBP_MCO_20) = 0.001, and p(KBP_20 vs KBP_MCO_20) < 0.001. Only the first comparison showed a statistically insignificant variation. A trade-off optimized plan library with a minimal number of patients (20) yields better performance for serial structures (spinal cord and brainstem) compared to large manually optimized KBP libraries. For other organs at risk (OARs) and target dose coverage, although statistical differences were significant in most instances, the differences in physical dose were small and probably will not yield any significant clinical differences.

The goal of this study was to investigate the variability of target volume and parotid gland dose distribution for nasopharyngeal carcinoma (NPC), and to explore the shifting patterns of parotid gland centroid and neck radius during radiotherapy. Twenty patients with NPC were enrolled. The target volume dose difference between planning dose and recalculated dose on weekly CT was analyzed. The recalculated doses on every weekly CT were cumulated to assess the difference between delivered dose and planning dose. The relationship of parotid gland centroid deviation with dose was studied, and the shrinking distances of neck radius were calculated for cervical vertebra 1, 2, 3 levels (C1, C2, C3). The ratio of GTVs and CTVs doses on weekly CTs to the doses on planning CT was all above 0.98; the dose of PTVs on weekly CT tended to decrease compared with planning. RMD was defined as the ratio of the mean dose of the left and right parotid glands (L-PG, R-PG) to the planning mean dose. The fitted relationships of RMD and the deviation of centroid (D) for L-PG and R-PG were: RMD=0.37*D+0.98 (R = 0.62, p < 0.001) and RMD = 0.33*D+0.97 (R = 0.72, p < 0.001), respectively. The order of neck radius shrinking distance at different levels was C1>C2=C3. In this study, we quantitatively analyzed the dosimetric variabilities of target volumes, and established linear models of parotid gland dose and its centroid deviation, which provides fractional and full-course dose evaluation during radiotherapy for NPC.

To study dosimetric effects of leaf positioning errors (LPEs) of the Halcyon(2.0) dual-layer MLC on the long-course chemoradiotherapy (LCCRT) with 45∼50.4 Gy in 25∼28 fractions for rectal cancer. Nine Halcyon(2.0)-based LCCRT plans of rectal cancer were retrospectively involved. Four types of LPEs were introduced: (1) Uniformly distributed dual-layer random LPEs (Dual-R); (2) Proximal-layer systemic LPEs (P-S); (3) Distal-layer systemic LPEs (D-S); (4) Dual-layer systemic LPEs (Dual-S). The sensitivities of D, D and the Equivalent Uniform Dose (EUD) of PTV to various LPEs were investigated as well as varying ranges of EUDs of OARs. The sensitivities of D and EUD of PTV to Dual-R was -0.65%/mm and -0.38%/mm; the sensitivities of both indices to the P-S and D-S were similar to each other, ranging from 1.92%/mm to 2.87%/mm; both indices were more sensitive to the Dual-S and values were 4.97%/mm and 3.84%/mm respectively. The EUD changes of the bladder, and left and right femoral heads were from -13.23% to 14.82%. Single-side systemic LPEs lower than 0.7 mm are acceptable for Halcyon(2.0)-based LCCRT, while dual-layer systemic LPEs lower than 0.4 mm are acceptable, considering relative changes of 2% for D of PTV as threshold.

To investigate the dosimetric impact of laterality-specific RapidPlan models for nonsmall cell lung cancer. Three RapidPlan models were developed and validated for Right, Left, and General conventional lung radiotherapy. Each model was trained using 50 plans. The right and left models consisted of plans corresponding to their respective laterality. Twenty-five cases were randomly chosen from each laterality-specific model to craft a general model. All models shared identical optimization objectives and the same target and OAR structures. Validation included 13 right-sided and 13 left-sided cases optimized using each RapidPlan model without intervention and normalized such that the prescription dose covered 95% of the target volume. Statistical analysis using a paired sample t-test (p < 0.01) assessed dosimetric endpoints based on RTOG 0617 criteria. For right-sided cases, spinal cord Dmax and D0.03cc were lowest in the left model and highest in the right model (21.08 Gy and 21.22 Gy vs 23.67 Gy and 24.08 Gy). D and D esophagus mean dose was also lower in the left model compared to the right model (p < 0.01) for both left and right-sided cases. However, overall plan quality exhibited no substantial difference between general and laterality-specific models. Despite observing small but statistically significant differences, there is no discernible difference in plan quality between laterality-specific and general models, suggesting that a single RapidPlan model is sufficient.

The virtual cone is an innovative MLC-based technique for generating dose distributions comparable to those of physical stereotactic cones. Initially designed for functional radiosurgery applications using a high-definition multileaf collimator (MLC) with 2.5 mm leaf width, this technique has been adapted to a standard 5 mm MLC system for treating small brain metastases. The adapted technique uses preconfigured location-specific control point sequences to produce spherical dose distributions with sharp dose gradients, and facilitates efficient planning through parallelizable template-based workflows. This report highlights the use of the adapted virtual cone technique for treating a 57-year-old patient with a 3 mm brain metastasis from metastatic papillary thyroid carcinoma using a standard multileaf collimator.

There has been no published work characterizing the attenuation of silicone breast implants in MV energy photon beams. As a result of systematic out of tolerance in-vivo dosimetry results, this report investigates whether the CT Hounsfield Units to electron density curve provides an accurate estimate of attenuation in silicone implants. A CT scan of a silicone breast implant centered on top of WT1 blocks was acquired with simple 6 MV and 10 MV plans created. Dose was calculated using the CT and a collapsed cone algorithm. The predicted dose was compared to doses measured with ionization chamber at 2 points downstream of the implant. Predicted dose from the treatment planning system was 0.9-1.7% lower than measured. The use of a density override on the implant of water (1 g/cm) improved agreement to less than 1% for all energies and measurement depths. We conclude that the use of CT Hounsfield Units for silicone breast implants leads to an under-estimation of dose in MV photon fields. Dose accuracy has been shown to be improved in the treatment planning system when silicone breast implants have a density override of water.

Head and Neck (H&N) cancer accounts for 3% of cancer cases in the United States. Precise tumor segmentation in H&N is of utmost importance for treatment planning and administering personalized treatment dose. We aimed to develop an automatic tumor localization and segmentation method in enhancing the clinical efficiency and ultimately improving treatment outcomes.

The present study aimed to improve the dose distribution of radiotherapy planning for nasopharyngeal carcinoma (NPC) by comparing the effects of various minimum monitor units (MUs) per dynamic control point (MMCP) values on the quality and execution efficiency of dynamic intensity-modulated radiotherapy (IMRT) planning. Thirty-four clinically implemented dynamic IMRT plans for patients with NPC were retrospectively selected. In total, 170 plans were obtained by modifying only the MMCP values (set as 1, 3, 5, 7, and 9) in the treatment planning system's (TPS) optimization parameters. These plans were divided into 5 groups. Analyzing the effects of MMCP on the target and organ dose at risk (OAR), also the execution efficiency of the treatment plan in each group and using a quality score system, we conducted an objective quantitative study of the dose distribution and execution efficiency. The target dose evaluation indicators (target coverage (TC), homogeneity index (HI), and conformity index (CI)) of all IMRT plans showed a trend of variation with an increase in MMCP values, and the difference was statistically significant when MMCP values were 5, 7, 9, and 1 (p < 0.05). With an increase in MMCP, the dose to OAR slightly increased, but the difference was not statistically significant (p > 0.05). With an increase in MMCP, the average number of MUs per segment significantly increased (p < 0.01). The groups based on MMCP values of 1, 3, 5, 7, and 9 received quality score system of 1.188, 1.180, 1.171, 0.987, and 1.184, respectively, with the MMCP7 group achieving the lowest score, indicating that this plan had the highest overall quality. The MMCP value for dynamic IMRT planning in the Monaco TPS for patients with NPC should be set to 7 to achieve fewer segments, the best execution efficiency without significantly deteriorating the target and OAR dose.