Improved quality of life in head and neck cancer patients treated with modern arc radiotherapy techniques - A prospective longitudinal analysis.

Purpose: The present longitudinal study aimed to evaluate the potential impact of modern radiotherapy (RT) techniques on quality of life (QOL) in patients with head and neck (HNC) cancer. Materials and methods: In this single-center prospective study, participants were asked to complete QOL questionnaires that included the EORTC QLQ-C30, QLQ-H&N 35 and utility score by time trade-off (TTO) at three time points (2 weeks, 3 months and 6 months) after completion of RT. All patients were treated by modern RT techniques [volumetric modulated arc therapy (VMAT) or helical tomotherapy (HT)]. Patients who developed recurrence or died before the 6-month follow-up were excluded. Linear mixed models with random intercepts for participants and restricted maximum likelihood estimates were used to assess the effect of our study variables (age, sex, primary site, cancer stage, treatment, radiation dose and radiation method). Overall changes in QOL, utility scores and symptom burdens at different time points were tested using paired t tests. Results: A total of 45 patients were recruited from 2022 to 2023. Those who completed the surveys at 2 weeks with at least 1 follow-up (30 patients, 67%) were enrolled in the final analysis. The majority of these 30 patients were men (76.7%), had oral cancer (40%), had stage III or IV disease (60%), received surgical intervention (63%) and were treated with chemoradiation (80%). A curative total dose of 66 to 70 Gy was delivered to 23 (76.7%) patients, half of whom received HT. Patients who received chemotherapy had significantly lower global QoL scales (mean difference, 27.94; 95% CI, 9.33-46.55; p=0.005). Global QOL, physical function, symptoms of sticky saliva, cough, feelings of illness and weight loss improved significantly between 2 weeks and 3 months. There was no significant difference between 3 and 6 months. Interestingly, improvements in social function, social contact, pain and nutrition reached significance at 6 months. Subgroup analysis revealed greater pain relief over time for patients who underwent HT (p=0.030). Moreover, patients who participated in swallowing rehabilitation programs had a greater decrease in nausea and vomiting (p=0.036). Conclusion: HNC patients treated with modern RT techniques experience improved QOL and physical function over time. The most significant improvement occurs between 2 weeks and 3 months, after which the improvement plateaus. However, social function, social contact, pain and nutrition may require longer recovery intervals after treatment. HT with daily image guidance could provide a therapeutic opportunity for improving pain relief in patients with HNC.

Evaluation and Comparison of the Dose Received by the Mandible, Maxilla, and Teeth in Two Methods of Three-dimensional Conformal Radiation Therapy and Helical Tomotherapy.

Background: Using three-dimensional conformal radiation treatment (3D-CRT) and helical tomotherapy (HT), this study examines and contrasts the dosage received by the mandible, maxilla, and teeth. Methods: Sixteen patients with head-and-neck cancer (H and NC) were the subject of treatment planning at the Seyyed Al-Shohada Hospital in Isfahan, Iran. This study examined target coverage quality, exposure of healthy tissue, and radiation delivery effectiveness. Results: In terms of a number of measures, including D2%, D50%, Dmean, V95%, conformity index (CI), and homogeneity index (HI) for the planning target volume (PTV) and D2%, D98%, Dmean, V95%, CI, and HI for the nodal PTV, HT showed considerable gains over 3D-CRT. The brainstem, D1cc, and D10cc received considerably lower maximum dosages in HT. Measurements of the right and left cochleas (Dmean, V55, and Dmax) revealed decreases in HT, with Dmean revealing the most significant variations. The Dmean and Dmax values for HT significantly decreased in constrictors as well. In terms of several HT-related indicators, the larynx, optic chiasm, optic nerves, oral cavity, mandible, thyroid, and parotid glands all showed considerable decreases. Conclusion: The findings of the comparison of the two treatment approaches revealed that the HT method was more than 50% more effective than the 3D-CRT method in sustaining organs at risk (OARs) and the target volume dose. In general, dosimetric coverage, homogeneity, conformity indices, and the absence of cold and hot patches showed that HT produced targets with greater accuracy than 3D-CRT. In addition, HT outperformed 3D-CRT in protecting important structures (OARs). HT as a result has the potential to be a more effective method of treatment for those with H and NC and involvement of regional lymph nodes.

Clinical implementation and patient-specific quality assurance solutions for real-time target tracking and dynamic delivery in Radixact synchrony.

BACKGROUND: The installation and testing of the first Radixact with Synchrony system in Colombia marked a significant milestone in Latin America's medical landscape. There was a need to devise a robust quality assurance protocol to comprehensively evaluate both dose delivery and motion tracking accuracy. However, testing experiences under clinical conditions have not been extensively reported. Additionally, there are limited recommended measuring devices for Synchrony evaluation. PURPOSE: To validate and implement an alternative setup for dynamic-PSQA while testing Synchrony's functionality under clinical scenarios, including real-patient motion traces, and to provide guidance to new centers undergoing clinical implementation of Helical Synchrony. METHODS: This approach involves using the Iba miniPhantomR with strategically placed fiducial markers for configuring Gafchromic-films and array-based setups. When paired with the CIRS Dynamic Platform, this enables an innovative dynamic setup with trackable features for Synchrony delivery testing. Assessment scenarios, including compensation (M1S1) and no-motion compensation (M1S0), were evaluated using 2D-gamma pass rate analysis with multiple clinical gamma criteria. The Synchrony-Simulation feature was used to assess pre-treatment performance and capture the patient's target motion pattern. Synchrony for common clinical cases with patient's motion-traces was validated. RESULTS: The results for M1S0 and M1S1 demonstrated consistency with previous studies evaluating Synchrony functionality. Analysis using different gamma criteria unveiled dosimetric differences and impacts across various motion ranges. The application of effective kV-dose subtraction for array-based methods is of upmost importance when evaluating dynamic-PSQA with stringent gamma-criteria. However, no significant kV-dose impact on EBT3-Film was detectable. CONCLUSION: Two implemented configurations for dynamic-PSQA setups were validated and successfully integrated into our clinic. We addressed both the benefits and limitations of array-based and film-based methods. The functionality and limitations of Synchrony were evaluated using the proposed setups. The potential utility of Synchrony-Simulation, along with the proposed patient-case classification table, can offer valuable support for new users during the clinical implementation of Synchrony treatments.

Nested CNN architecture for three-dimensional dose distribution prediction in tomotherapy for prostate cancer.

BACKGROUND: The hypothesis of changing network layers to increase the accuracy of dose distribution prediction, instead of expanding their dimensions, which requires complex calculations, has been considered in our study. MATERIALS AND METHODS: A total of 137 prostate cancer patients treated with the tomotherapy technique were categorized as 80% training and validating as well as 20% testing for the nested UNet and UNet architectures. Mean absolute error (MAE) was used to measure the dosimetry indices of dose-volume histograms (DVHs), and geometry indices, including the structural similarity index measure (SSIM), dice similarity coefficient (DSC), and Jaccard similarity coefficient (JSC), were used to evaluate the isodose volume (IV) similarity prediction. To verify a statistically significant difference, the two-way statistical Wilcoxon test was used at a level of 0.05 (p < 0.05). RESULTS: Use of a nested UNet architecture reduced the predicted dose MAE in DVH indices. The MAE for planning target volume (PTV), bladder, rectum, and right and left femur were D98% = 1.11 ± 0.90; D98% = 2.27 ± 2.85, Dmean = 0.84 ± 0.62; D98% = 1.47 ± 12.02, Dmean = 0.77 ± 1.59; D2% = 0.65 ± 0.70, Dmean = 0.96 ± 2.82; and D2% = 1.18 ± 6.65, Dmean = 0.44 ± 1.13, respectively. Additionally, the greatest geometric similarity was observed in the mean SSIM for UNet and nested UNet (0.91 vs. 0.94, respectively). CONCLUSION: The nested UNet network can be considered a suitable network due to its ability to improve the accuracy of dose distribution prediction compared to the UNet network in an acceptable time.

Development of an external system for monitoring the couch speed in radiotherapy using continuous bed movement.

PURPOSE: Total body irradiation before bone marrow transplantation for hematological malignancies using Radixact, a high-precision radiotherapy machine, can potentially reduce side effects and the risk of secondary malignancies. However, stable control of couch speed is critical, and direct assessment methods outlined in quality assurance guidelines are lacking. This study aims to develop a real-time couch speed verification system for the Radixact. METHODS: The developed system used a linear encoder to measure couch speed directly. Accuracy was verified via a linear stage, comparing measurements with a laser distance sensor. After placing a phantom simulating the human body on the Radixact couch, the couch speed was verified using predefined speed plans. RESULTS: Operating the linear stage at 0.1, 0.5, and 1.0 mm/s revealed that the maximum position error of the developed verification system compared to the laser distance sensor was nearly equivalent to the distance resolution of the system (0.05 mm/pulse), with negligible average speed error. When the Radixact couch operated at 0.1, 0.5, and 1.0 mm/s, the values obtained by the verification system agreed with the theoretical values within the sampling period (0.01 s) and distance resolution (0.05 mm). CONCLUSION: The verification system developed provides real-time monitoring of the speed of the Radixact table, ensuring treatment effectiveness and patient safety. It would guarantee the couch speed's soundness and contribute to the "visualization" of safety.

Evaluation of helical tomotherapy as an alternative for left-sided breast cancer patients not compliant with deep inspiration breath hold.

Purpose: The aim of this study is to investigate, from a dosimetric perspective, whether helical Tomotherapy (HT) during free breathing (FB) can serve as an alternative technique for treating left-sided breast cancer patients who are unable to comply with the deep inspiration breath hold (DIBH) technique. Material and Methods: For this purpose, the CT images of 20 left breast-only cancer patients acquired in both FB and DIBH phases were utilized. The left breast was contoured as the target volume, while the heart, LAD, ipsilateral and contralateral lungs, and contralateral breast were contoured as organs at risk on the CT images obtained in both DIBH and FB. Planning with the volumetric modulated arc therapy (VMAT) technique was performed on the CT scans obtained in the DIBH (VMAT-DIBH), while planning with the HT technique was carried out on the CT scans obtained in the FB (HT-FB). Subsequently, dosimetric comparison of the plans were done in terms of target coverage and preservation of normal tissues. Results: Both techniques achieved the desired target coverage; however, in terms of D2, Vpres values, Conformity Number (CN), and Homogeneity Index (HI), the HT-FB technique was found to be superior. While the mean doses to the heart were similar for both techniques, doses to the LAD and left lung were found to be superior in plans generated with the HT-FB technique. When compared in terms of contralateral breast and right lung protection, VMAT-DIBH technique was found to be significantly superior. Conclusion: The treatment of left breast-only patients with the HT-FB technique has been observed to provide similar heart protection and better LAD and ipsilateral lung protection compared to the VMAT-DIBH technique without compromising target coverage. However, when the HT-FB technique is used, doses to the contralateral lung and contralateral breast should be carefully evaluated.

Performance of binary MLC using real-time optical sensor feedback system.

The Radixact system (Accuray Inc., Sunnyvale, CA) is the latest platform release based on the TomoTherapy technology. The most recent system does not apply a leaf latency model correction after plan optimization to ensure the correct MLC leaf-open time (LOT) agreement between the TPS and machine delivery. The MLC uses optical sensors to measure the delivered LOTs in real-time and individual leaf-specific latency corrections are made to ensure agreement. The aim of this study was to assess the performance of the Radixact MLC with leaf-specific latency correction using the optical sensor's real-time feedback. Specifically, the study statistically evaluated the MLC LOT errors observed from 290 plan-specific quality assurance (PSQA) measurements. Repeatability testing was performed to quantify the uncertainty in the MLC feedback system delivery by analyzing > 1300 delivered treatment fractions throughout the course of radiotherapy. The clinical impact was evaluated by estimating the resulting dose difference in the patient targets due to the measured plan latencies. Our study measured an average plan latency equal to 2.0 ± 0.4 ms (0.6% ± 0.2%) for 290 PSQAs. Repeatability tests showed a mean standard deviation in plan latencies measuring 0.05 ms (0.02%). The deviation from the TPS in the mean target dose due to the plan latencies was estimated to be 0.0% ± 0.2% (range: -0.7%-1.1%). The current MLC system with real-time optical sensor feedback is capable of accurately delivering the TPS-generated sinograms. Repeatability test results showed that the system allows for high reliability in daily sinogram delivery. The MLC latency deviations were shown to have minimal clinical impact on the overall target dosimetry.

Half body irradiation (HBI) for bone metastases in the modern radiotherapy technique era - A systematic review.

Bone metastases (BMs) are the most common cause of cancer-related pain and radiation therapy plays a key role in treating pain caused by it. The half-body irradiation (HBI) is a modality that can be used to treat patients with multiple painful BMs. In the modern era, concerns about toxicity and the availability of new agents requiring robust bone marrow function have limited the use of HBI in advanced cancer. Concerns about HBI toxicity stem from outdated techniques; modern methods like volumetric modulated arc therapy (VMAT) and helical tomotherapy now allow safer irradiation of complex target volumes. We conducted a systematic review to present updated information about HBI efficacy and potential toxicity. Pain relief usually occurs very quickly 2-3 weeks after HBI. The overall pain response rate was high in all the series, accounting for a median of 84 % (75.6-89 %), with a median of 36 % complete pain response. The toxicity is usually limited to G1/G2, with very rare G3 cases. More than 50 % of patients can reduce analgesic intake after HBI. Additionally, with modern radiotherapy techniques, quality of life is improved in most patients. HBI is a safe and effective method and should once again be reconsidered for more frequent use.

Comparison of Different Head Tilt Angles in Tomotherapy and Volumetric Modulated Arc Therapy for Hippocampal-Avoidance Whole-Brain Radiotherapy.

PURPOSE: Hippocampal-avoidance whole-brain radiotherapy (HA-WBRT) planning can present challenges. This study examines the influence of head tilt angles on the dosimetric characteristics of target and organs at risk (OARs), aiming to identify the optimal tilt angle that yields optimal dosimetric outcomes using tomotherapy (TOMO). METHODS: Eight patients diagnosed with brain metastases underwent CT scans at five tilt angles: [0°, 10°), [10°, 20°), [20°, 30°), [30°, 40°), and [40°, 45°]. Treatment plans were generated using TOMO and volumetric modulated arc therapy (VMAT). Dosimetric parameters including conformity index (CI), homogeneity index (HI), D2cc, D98%, and Dmean of PTV, as well as Dmax, and Dmean of OARs were analyzed. Furthermore, a comparison was made between the dosimetric parameters of TOMO and VMAT plans. Finally, delivery efficiency of TOMO plans were assessed. RESULTS: For the PTV, [40°, 45°] tilt angle demonstrated significantly better conformity, homogeneity, lower D2cc, and lower Dmean for the PTV. Regarding the OARs, the [40°, 45°] head tilt angle demonstrated significantly lower Dmax and Dmean in hippocampus, eyes, optic chiasm, and optic nerves. The [40°, 45°] tilt angle also showed significantly lower Dmax for brainstem and cochleas, as well as a lower Dmean for lens. In the [40°,45°] tilt angle for HA-WBRT, TOMO showed superior performance over VMAT for the PTV. TOMO achieved lower Dmax for brainstem, cochleas, optic nerves, and optic chiasm, as well as a lower Dmean for hippocampus. Furthermore, a significant correlation was found between delivery time and the PTV projection length in the sagittal plane. CONCLUSION: The TOMO plan utilizing a tilt angle range of [40°, 45°] demonstrated superior PTV conformity and uniformity, along with enhanced OARs sparing. Furthermore, it exhibited a dosimetric advantage over VMAT for PTV and most OARs at the same angle range.

Incorporating intensity modulated total body irradiation into a Children's Oncology Group trial: Rationale, techniques, and safeguards.

Historically, total body irradiation (TBI) has been delivered using static, parallel opposed photon beams (2D-TBI). Recently, centers have increasingly used intensity-modulated radiation therapy (IMRT) techniques for TBI. Relative to 2D-TBI, IMRT can reduce doses to critical organs (i.e., lungs and kidneys) while delivering myeloablative doses to the rest of the body, so it may decrease the risk of toxicity while maintaining oncologic outcomes. Despite these potential benefits, delivering TBI using IMRT introduces new challenges in treatment planning and delivery. We describe the extensive experience with IMRT-based TBI at Stanford University and City of Hope Cancer Center. These groups, and others, have reported favorable clinical outcomes and have developed methods to optimize treatment planning and delivery. A critical next step is to evaluate the broader adoption of this approach. Therefore, IMRT-based TBI will be incorporated into a prospective, multi-institutional Children's Oncology Group study with careful procedures and safeguards in place.

Validation of MLC leaf open time calculation methods for PSQA in adaptive radiotherapy with tomotherapy units.

BACKGROUND: Treatment delivery safety and accuracy are essential to control the disease and protect healthy tissues in radiation therapy. For usual treatment, a phantom-based patient specific quality assurance (PSQA) is performed to verify the delivery prior to the treatment. The emergence of adaptive radiation therapy (ART) adds new complexities to PSQA. In fact, organ at risks and target volume re-contouring as well as plan re-optimization and treatment delivery are performed with the patient immobilized on the treatment couch, making phantom-based pretreatment PSQA impractical. In this case, phantomless PSQA tools based on multileaf collimator (MLC) leaf open times (LOTs) verifications provide alternative approaches for the Radixact® treatment units. However, their validity is compromised by the lack of independent and reliable methods for calculating the LOT performed by the MLC during deliveries. PURPOSE: To provide independent and reliable methods of LOT calculation for the Radixact® treatment units. METHODS: Two methods for calculating the LOTs performed by the MLC during deliveries have been implemented. The first method uses the signal recorded by the build-in detector and the second method uses the signal recorded by optical sensors mounted on the MLC. To calibrate the methods to the ground truth, in-phantom ionization chamber LOT measurements have been conducted on a Radixact® treatment unit. The methods were validated by comparing LOT calculations with in-phantom ionization chamber LOT measurements performed on two Radixact® treatment units. RESULTS: The study shows a good agreement between the two LOT calculation methods and the in-phantom ionization chamber measurements. There are no notable differences between the two methods and the same results were observed on the different treatment units. CONCLUSIONS: The two implemented methods have the potential to be part of a PSQA solution for ART in tomotherapy.

Surface guided ring gantry radiotherapy in deep inspiration breath hold for breast cancer patients.

PURPOSE: This study investigated the use of surface guided radiotherapy (SGRT) in combination with a tomotherapy treatment mode using discrete delivery angles for deep inspiration breath hold (DIBH) treatments of breast cancer (bc). We aimed to assess the feasibility and dosimetric advantages of this approach. MATERIALS AND METHODS: We evaluated camera occlusion in the Radixact treatment system bore and the stability of DIBH signals during couch movement. The SGRT system's ability to maintain signal and surface image accuracy was analyzed at different depths within the bore. Dosimetric parameters were compared and measured for 20 left-sided bc patients receiving TomoDirect (TD) tangential radiotherapy in both DIBH and free breathing (FB). RESULTS: The SGRT system maintained surface coverage and precise DIBH-signal at depths up to 40 cm beyond the treatment center. Camera occlusion occurred in the clavicular and neck regions due to the patient's morphology and gantry geometry. Nonetheless, the system accurately detected respiratory motion for all measurements. The DIBH plans significantly (p < 0.001) reduced mean heart and left anterior descending artery (LAD) radiation doses by up to 40%, with a 50% reduction in near-maximum heart and LAD doses, respectively. No significant dosimetric differences between DIBH and FB were observed in other investigated parameters and volumes. CONCLUSIONS: Camera occlusion and couch movement minimally impacted the real-time surface image accuracy needed for DIBH treatments of bc. DIBH reduced heart and LAD radiation doses significantly compared to FB, indicating the feasibility and dosimetric benefits of combining these modalities.

Evaluation of the Treatment Planning and Delivery for Hip Implant Cases on Tomotherapy.

Purpose: The metal present in the implant creates artifacts during the treatment simulation, which impacts the treatment planning and delivery of the prescribed dose to the target and sparing normal tissues. This retrospective study evaluated the uncertainties in the planning and delivery of doses for prosthesis cases with dedicated phantom. Materials and Methods: In this retrospective study, 11 patients with a hip prosthesis having cervix carcinoma were selected. Two treatment plans were generated on treatment planning system (TPS) for each case. Plan_No_Res was without any beam restriction, and Plan_exit_only was the plan with restricted beam entry through the metallic implant. An indigenous phantom was utilized to verify the accuracy of the treatment. In the phantom, some groves were present, which could be filled by implants that mimic the patient's geometries, like left, right and bilateral femur implants. The delivered doses were recorded using optically stimulated luminescence dosimeters (OSLDs), which were placed at different positions in the phantom. The plans were further calculated using megavoltage computed tomography (MVCT) scans acquired during treatment. Results: The patient data showed no significant dose changes between the two planning methods. The treatment time increases from 412.18 ± 86.65 to 427.36 ± 104.80 with P = 0.03 for Plan_No_Res and Plan_exit_only, respectively. The difference between planned and delivered doses of various points across phantom geometries was within ± 9.5% in each case as left, right, and bilateral implant. The variations between OSLDs and MVCT calculated doses were also within ± 10.8%. Conclusion: The study showed the competency of tomotherapy planning for hip prosthesis cases. The phantom measurements demonstrate the errors in dosimetry near the implant material, suggesting the need for precise methods to deal with artifact-related issues.

Development and validation of an automated Tomotherapy planning method for cervical cancer.

PURPOSE: This study aimed to develop an automated Tomotherapy (TOMO) planning method for cervical cancer treatment, and to validate its feasibility and effectiveness. MATERIALS AND METHODS: The study enrolled 30 cervical cancer patients treated with TOMO at our center. Utilizing scripting and Python environment within the RayStation (RaySearch Labs, Sweden) treatment planning system (TPS), we developed automated planning methods for TOMO and volumetric modulated arc therapy (VMAT) techniques. The clinical manual TOMO (M-TOMO) plans for the 30 patients were re-optimized using automated planning scripts for both TOMO and VMAT, creating automated TOMO (A-TOMO) and automated VMAT (A-VMAT) plans. We compared A-TOMO with M-TOMO and A-VMAT plans. The primary evaluated relevant dosimetric parameters and treatment plan efficiency were assessed using the two-sided Wilcoxon signed-rank test for statistical analysis, with a P-value < 0.05 indicating statistical significance. RESULTS: A-TOMO plans maintained similar target dose uniformity compared to M-TOMO plans, with improvements in target conformity and faster dose drop-off outside the target, and demonstrated significant statistical differences (P+ < 0.01). A-TOMO plans also significantly outperformed M-TOMO plans in reducing V50Gy, V40Gy and Dmean for the bladder and rectum, as well as Dmean for the bowel bag, femoral heads, and kidneys (all P+ < 0.05). Additionally, A-TOMO plans demonstrated better consistency in plan quality. Furthermore, the quality of A-TOMO plans was comparable to or superior than A-VMAT plans. In terms of efficiency, A-TOMO significantly reduced the time required for treatment planning to approximately 20 min. CONCLUSION: We have successfully developed an A-TOMO planning method for cervical cancer. Compared to M-TOMO plans, A-TOMO plans improved target conformity and reduced radiation dose to OARs. Additionally, the quality of A-TOMO plans was on par with or surpasses that of A-VMAT plans. The A-TOMO planning method significantly improved the efficiency of treatment planning.

Long-term Outcome After Helical Tomotherapy Following Breast Conserving Surgery for Ductal Carcinoma In Situ.

Background: This retrospective study aimed to investigate the outcomes and adverse events (AEs) associated with adjuvant radiotherapy with helical tomotherapy (hT) after breast-conserving surgery (BCS) for ductal carcinoma in situ (DCIS). Methods: Twenty-eight patients with DCIS underwent postoperative hT between 2011 and 2020. hT was chosen since it provided optimal target coverage and tolerable organ-at-risk doses to the lungs and heart when tangential 3-dimensional conformal radiotherapy (3D-CRT) was presumed to provide unfavorable dosimetry. The median total (single) dose was 50.4 Gy (1.8 Gy). The median time between BCS and the start of hT was 5 weeks (range, 4-38 weeks). Statistical analysis included local recurrence-free survival, overall survival (OS), and secondary cancer-free survival. AEs were classified according to the Common Toxicity Criteria for Adverse Events, version 5. Results: The patients' median age was 58 years. The median follow-up period was 61 months (range, 3-123 months). The 1-, 3-, and 5-year OS rates were 100% each. None of the patients developed secondary cancer, local recurrence, or invasive breast cancer during follow-up. The most common acute AEs were dermatitis (n = 27), fatigue (n = 4), hyperpigmentation (n = 3), and thrombocytopenia (n = 4). The late AE primarily included surgical scars (n = 7) and hyperpigmentation (n = 5). None of the patients experienced acute or late AEs > grade 3. The mean conformity and homogeneity indices were 0.9 (range, 0.86-0.96) and 0.056 (range, 0.05-0.06), respectively. Conclusion: hT after BCS for DCIS is a feasible and safe form of adjuvant radiotherapy for patients in whom 3D-CRT is contraindicated due to unfavorable dosimetry. During follow-up, there were no recurrences, invasive breast cancer diagnoses, or secondary cancers, while the adverse effects were mild.

Dosiomics-based detection of dose distribution variations in helical tomotherapy for prostate cancer patients: influence of treatment plan parameters.

The stability of dosiomics features (DFs) and dose-volume histogram (DVH) parameters for detecting disparities in helical tomotherapy planned dose distributions was assessed. Treatment plans of 18 prostate patients were recalculated using the followings: field width (WF) (2.5 vs. 5), pitch factor (PF) (0.433 vs. 0.444), and modulation factor (MF) (2.5 vs. 3). From each of the eight plans per patient, ninety-three original and 744 wavelet-based DFs were extracted, using 3D-Slicer software, across six regions including: target volume (PTV), pelvic lymph nodes (PTV-LN), PTV + PTV-LN (PTV-All), one cm rind around PTV-All (PTV-Ring), rectum, and bladder. For the resulting DFs and DVH parameters, the coefficient of variation (CV) was calculated, and using hierarchical clustering, the features were classified into low/high variability. The significance of parameters on instability was analyzed by a three-way analysis of variance. All DF's were stable in PTV, PTV-LN, and PTV-Ring (average CV ( CV ¯ )  ≤ 0.36). Only one feature in the bladder ( CV ¯  = 0.9), rectum ( CV ¯  = 0.4), and PTV-All ( CV ¯  = 0.37) were considered unstable due to change in MF in the bladder and WF in the PTV-All. The value of CV ¯ for the wavelet features was much higher than that for the original features. Out of 225 unstable wavelet features, 84 features had CV ¯  ≥ 1. The CVs for all the DVHs remained very small ( CV ¯ < 0.06). This study highlights that the sensitivity of DFs to changes in tomotherapy planning parameters is influenced by the region and the DFs, particularly wavelet features, surpassing the effectiveness of DVHs.

Comparison of Doses to Parotid, Temporomandibular Joint, and Pharyngeal Constrictor Muscles Using Different Techniques in Radiotherapy for Oropharyngeal Cancer.

OBJECTIVE: The purpose of this research was to compare two treatment techniques for oropharyngeal cancers: conventional linac-based static intensity-modulated radiotherapy (sIMRT) and helical tomotherapy (HT). The study examined several parameters, including target coverage, organs at risk, integral dose, and beam on time. Additionally, the study evaluated the doses to the parotid, temporomandibular joint, and pharyngeal constrictor muscles, which are important for swallowing. METHOD: The present study retrospectively analyzed the data of 13 patients with oropharyngeal cancer who underwent radiotherapy between 2019 and 2021. The treatment plans for each patient were regenerated using both sIMRT and HT treatment planning systems with the sequential boost method. The techniques were evaluated and compared based on dose-volume histogram, homogeneity index, and conformity index parameters. The target coverage and organs at risk were statistically compared for two techniques. Additionally, the doses received by the healthy tissue volume were obtained for integral dose evaluation. The beam on time for each technique was assessed. RESULTS: When considering planning target volume evaluation, there was no difference in Dmeans between the two techniques and sIMRT demonstrated higher D2% values compared to the HT. The HT technique had better results for all organs at risk, such as the parotid, temporomandibular joint, and pharyngeal constrictor muscle. As for integral dose, it has been shown that the sIMRT technique provides better protection compared to HT. In addition, the beam on time was also longer with the HT technique. CONCLUSION: Both techniques may provide optimal target coverage for patients with oropharyngeal cancer. HT conferred notable advantages, especially with regard to critical structures implicated in swallowing, such as the parotid, temporomandibular joint, and pharyngeal constrictor muscle, in comparison to sIMRT.

Using dose volume histogram (DVH) predictions to improve the plan quality of helical tomotherapy (HT).

This study aimed to investigate whether the RapidPlan (RP) model configured by volumetric modulated arc therapy (VMAT) plans of nasopharyngeal carcinoma (NPC) could be used to assist in the optimization of HT plans and improve their quality. An RP model was trained using 100 clinically accepted VMAT plans of NPC patients. The predicted dose constraints of the VMAT trained RP model were used to reoptimize 25 consecutive clinically accepted HT plans (HT_clinical) and perform new VMAT plans based on the same computed topography (CT). The dosimetric quality of the reoptimized HT plans (HT_reoptimized), HT_clinical, and VMAT group were compared. The minimum dose encompassing 2% target (D2%), the minimum dose encompassing 98% target (D98%), homogeneity index (HI) and conformity index (CI) were similar for most targets between the HT_clinical and HT_reoptimized plans, although certain targets in the HT_reoptimized plans had higher D2% and HI and lower D98%. The HT_reoptimized plans outperformed the HT_clinical plans in the Dmax and D1cc of the spinal cord, V40Gy of the left temporal lobe, Dmean and V30Gy of the oral cavity, Dmean of the larynx and thyroid, and the differences were statistically significant. HT plans had higher CI and HI than VMAT plans. HT plans outperformed VMAT plans in the Dmax of the spinal cord and lenses, V30Gy of the oral cavity and parotids, and V40Gy of the temporal lobes, but underperformed in the Dmax and D1cc of the brainstem, D1cc of the spinal cord and Dmean of the oral cavity. The VMAT-based RP model can be used to assist in the planning of HT plans and improve the dosimetry quality of HT plans.

18F-fluorodeoxyglucose PET-CT-guided pelvic chemoradiation therapy using helical tomotherapy for locally advanced carcinoma cervix without para-aortic nodal disease: Clinical and patient-reported outcomes from a prospective phase 2 study.

INTRODUCTION: Locally advanced carcinoma cervix (LACC) is a heterogeneous disease with variable combinations of primary tumour extensions with or without nodal involvement. Metabolic information from 18 fluro-deoxyglucose positron emission tomography combined with contrast-enhanced computerized tomography (FDG PET-CT) may potentially augment treatment decision-making for LACC. This study ascertained FDG-PET CT influence on chemoradiation therapy (CTRT) decisions in LACC. We report oncologic and patient-reported outcome measures (PROMs). METHODS: FDG PET-CT scans were reviewed independently by two nuclear medicine specialists and two radiation oncologists. Pelvic CTRT plan digressions were documented and therapy was adapted accordingly. Pelvis radiation (50 Gy/25#/5 weeks) using tomotherapy with weekly cisplatin was used in node-negative disease. Dose-escalated simultaneous integrated boost (SIB) 60 Gy/25#/5 weeks was delivered to involved pelvic nodes. All received brachytherapy. Post-treatment PET-CT scans were at 6 months. Functional assessment of cancer therapy scores were calculated at baseline, treatment completion, 3 months, 1 year and 3 years. RESULTS: Between November 2015 and January 2018, 85 patients were screened, and 77 consented. Extrapelvic disease was seen in 12 (16%) patients (9 para-aortic nodes, 2 distant metastases and 1 synchronous carcinoma breast); 60 patients were included in the final analysis. Decision changes were seen in 10/77 (13%) screened, 8/60 (13%) included and 32 (53.3%) received SIB. Post-treatment, 27 (45%) had grade 2 GI/GU/GYN toxicity, one (2%) had grade 3 GI and five (8.3%) had grade 3 neutropenia. At median overall survival of 54.2 months (95% CI 52.8-58.3), 5-year local failure, pelvic nodal and para-aortic nodal-free survival were 86.8% (95% CI 78.0-96.6), 85.2% (95% CI 76.1-95.3) and 85.2% (95% CI 76.2-95.4). Functional assessment of cancer therapy trial outcome index (FACT TOI) improved by 10.43 at 3 months with no further decline. Grade 3 toxicity was noted for abdominal pain in one (1.7%), cystitis in four (6.7%) and lymphoedema in one (1.7%) at 5 years. CONCLUSION: PET-CT resulted in major decision changes in 13%. PET-adapted CTRT was associated with acceptable toxicity, encouraging long-term survival and improvement in PROMS.

Technical recommendations for implementation of Volumetric Modulated Arc Therapy and Helical Tomotherapy Total Body Irradiation.

As a component of myeloablative conditioning before allogeneic hematopoietic stem cell transplantation (HSCT), Total Body Irradiation (TBI) is employed in radiotherapy centers all over the world. In recent and coming years, many centers are changing their technical setup from a conventional TBI technique to multi-isocenter conformal arc therapy techniques such as Volumetric Modulated Arc Therapy (VMAT) or Helical Tomotherapy (HT). These techniques allow better homogeneity and control of the target prescription dose, and provide more freedom for individualized organ-at-risk sparing. The technical design of multi-isocenter/multi-plan conformal TBI is complex and should be developed carefully. A group of early adopters with conformal TBI experience using different treatment machines and treatment planning systems came together to develop technical recommendations and share experiences, in order to assist departments wishing to implement conformal TBI, and to provide ideas for standardization of practices.