Comparison of volumetric modulated arc therapy and helical tomotherapy for prostate cancer using Pareto fronts

BACKGROUND

Studies comparing different radiotherapy treatment techniques-such as volumetric modulated arc therapy (VMAT) and helical tomotherapy (HT)-typically compare one treatment plan per technique. Often, some dose metrics favor one plan and others favor the other, so the final plan decision involves subjective preferences. Pareto front comparisons provide a more objective framework for comparing different treatment techniques. A Pareto front is the set of all treatment plans where improvement in one criterion is possible only by worsening another criterion. However, different Pareto fronts can be obtained depending on the chosen machine settings.

PURPOSE

To compare VMAT and HT using Pareto fronts and blind expert evaluation, to explain the observed differences, and to illustrate limitations of using Pareto fronts.

METHODS

We generated Pareto fronts for twenty-four prostate cancer patients treated at our clinic for VMAT and HT techniques using an in-house script that controlled a commercial treatment planning system. We varied the PTV under-coverage (100% - V95%) and the rectum mean dose, and fixed the mean doses to the bladder and femoral heads. In order to ensure a fair comparison, those fixed mean doses were the same for the two treatment techniques and the sets of objective functions were chosen so that the conformity indexes of the two treatment techniques were also the same. We used the same machine settings as are used in our clinic. Then, we compared the VMAT and HT Pareto fronts using a specific metric (clinical distance measure) and validated the comparison using a blinded expert evaluation of treatment plans on these fronts for all patients in the cohort. Furthermore, we investigated the observed differences between VMAT and HT and pointed out limitations of using Pareto fronts.

RESULTS

Both clinical distance and blind treatment plan comparison showed that VMAT Pareto fronts were better than HT fronts. VMAT fronts for 10 and 6 MV beam energy were almost identical. HT fronts improved with different machine settings, but were still inferior to VMAT fronts.

CONCLUSIONS

That VMAT Pareto fronts are better than HT fronts may be explained by the fact that the linear accelerator can rapidly vary the dose rate. This is an advantage in simple geometries that might vanish in more complex geometries. Furthermore, one should be cautious when speaking about Pareto optimal plans as the best possible plans, as their calculation depends on many parameters.

Clinical implementation of deep learning-based automated left breast simultaneous integrated boost radiotherapy treatment planning

Background and purpose

Automation in radiotherapy treatment planning aims to improve both the quality and the efficiency of the process. The aim of this study was to report on a clinical implementation of a Deep Learning (DL) auto-planning model for left-sided breast cancer.

Materials and methods

The DL model was developed for left-sided breast simultaneous integrated boost treatments under deep-inspiration breath-hold. Eighty manual dose distributions were revised and used for training. Ten patients were used for model validation. The model was then used to design 17 clinical auto-plans. Manual and auto-plans were scored on a list of clinical goals for both targets and organs-at-risk (OARs). For validation, predicted and mimicked dose (PD and MD, respectively) percent error (PE) was calculated with respect to manual dose. Clinical and validation cohorts were compared in terms of MD only.

Results

Median values of both PD and MD validation plans fulfilled the evaluation criteria. PE was < 1% for targets for both PD and MD. PD was well aligned to manual dose while MD left lung mean dose was significantly less (median:5.1 Gy vs 6.1 Gy). The left-anterior-descending artery maximum dose was found out of requirements (median values:+5.9 Gy and + 2.9 Gy, for PD and MD respectively) in three validation cases, while it was reduced for clinical cases (median:-1.9 Gy). No other clinically significant differences were observed between clinical and validation cohorts.

Conclusion

Small OAR differences observed during the model validation were not found clinically relevant. The clinical implementation outcomes confirmed the robustness of the model.

Influence of optimisation parameters on directly deliverable Pareto fronts explored for prostate cancer

PURPOSE

In inverse radiotherapy treatment planning, the Pareto front is the set of optimal solutions to the multi-criteria problem of adequately irradiating the planning target volume (PTV) while reducing dose to organs at risk (OAR). The Pareto front depends on the chosen optimisation parameters whose influence (clinically relevant versus not clinically relevant) is investigated in this paper.

METHODS

Thirty-one prostate cancer patients treated at our clinic were randomly selected. We developed an in-house Python script that controlled the commercial treatment planning system RayStation to calculate directly deliverable Pareto fronts. We calculated reference Pareto fronts for a given set of objective functions, varying the PTV coverage and the mean dose of the primary OAR (rectum) and fixing the mean doses of the secondary OARs (bladder and femoral heads). We calculated the fronts for different sets of objective functions and different mean doses to secondary OARs. We compared all fronts using a specific metric (clinical distance measure).

RESULTS

The in-house script was validated for directly deliverable Pareto front calculations in two and three dimensions. The Pareto fronts depended on the choice of objective functions and fixed mean doses to secondary OARs, whereas the parameters most influencing the front and leading to clinically relevant differences were the dose gradient around the PTV, the weight of the PTV objective function, and the bladder mean dose.

CONCLUSIONS

Our study suggests that for multi-criteria optimisation of prostate treatments using external therapy, dose gradient around the PTV and bladder mean dose are the most influencial parameters.

Toxicity, quality of life, and PSA control after 50 Gy stereotactic body radiation therapy to the dominant intraprostatic nodule with the use of a rectal spacer: results of a phase I/II study

OBJECTIVES

We conducted a phase I/II prospective trial to determine whether stereotactic dose escalation to the dominant intra-prostatic nodule (DIN) up to 50 Gy incorporating a rectal balloon spacer is safe, does not affect patient quality of life, and preserves local control in patients with intermediate-high risk PCa.

METHODS

Eligible patients included males with stage ≤T3b localized disease, a prostate-specific antigen (PSA) level ≤50 , International Prostate Symptom Score (IPSS) ≤14, and a gland volume ≤70 cm³. Patients underwent perirectal spacer placement, followed by a planning MRI and were subsequently treated with SBRT doses of 36.25 Gy in five fractions to the whole prostate while simultaneously escalating doses to the magnetic resonance image visible DIN up to 50 Gy. Primary endpoint: safety. Secondary endpoints: biochemical control, quality of life (QofL), and dosimetry outcome.

RESULTS

Nine patients were treated in the Phase I part of the study. Dose limiting toxicities (DLTs) were not observed. Further characterization of tolerability and efficacy was conducted in the subsequent 24 patients irradiated at the recommended Phase II dose (50 Gy, RP2D). At a median follow-up of 61 months, biochemical control is 69%. Grade 1 and 2 acute GU and GI toxicity was 57.5 and 15%, and 24.2 and 6.1%, respectively. Grade 1 and 2 late GU and GI toxicity was 66.6 and 12.1%, and 15.1 and 3%, respectively. No Grade 3 or higher toxicity was reported. QofL data confirmed physician's reported side effects. Dosimetry analysis showed adherence to the doses prescribed in the protocol.

CONCLUSIONS

SBRT of the whole prostate with 36.25 Gy in 5 fractions and dose escalation to 50 Gy to the DIN, when combined with a peri-rectal balloon spacer, was tolerable and established the RP2D. QofL analysis showed minimal negative impact in GU, GI, and sexual domains.

ADVANCES IN KNOWLEDGE

Extreme hypofractionated prostate radiation therapy with focal dose escalation to the DIN is well tolerated with efficacy comparable to normal fractionated radiation therapy.

Salvage LATTICE radiotherapy for a growing tumour despite conventional radio chemotherapy treatment of lung cancer

A 40-year-old patient with cT4cN1M0 squamous cell lung cancer of the upper right lobe received preoperative induction chemotherapy. Systemic induction treatment failed to reverse tumour growth with the addition of conventional radiotherapy (RT). A salvage lattice RT boost of 12 Gy was administered immediately to increase the dose to the tumour. Conventional RT was resumed at the planned dose of 60 Gy. The tumour shrank rapidly, and the patient was surged. The postoperative pathology remained ypT0ypN0 status.

On the interplay effect for moving targets treated with the CyberKnife static tracking system

PURPOSE

To assess the interplay effect amplitude between different planned MU distributions and respiratory patterns in the CyberKnife system when treating moving targets with static tracking technique.

METHODS

Small- and Large-Respiratory Motions (SRM and LRM) differing in amplitude and frequency were simulated in a semi-anthropomorphic dynamic thorax phantom. The interplay effect was evaluated for both respiration motions in terms of GTV coverage and conformity for three plans designed with an increasing range of MU per beam (small, medium and large). Each plan was delivered three times changing the initial beam-on phase to assess the inter-fraction variation. Dose distributions were measured using radiochromic films placed in the GTV axial and sagittal planes.

RESULTS

Generally, SRM plans gave higher GTV coverage and were less dependent on beam-on phases than LRM plans. For SRM (LRM) plans, the GTV coverage ranged from 95.2% to 99.7% (85.9% to 99.8%). Maximum GTV coverage was found for large MU plans in SRM and for small MU plans in LRM. Minimum GTV coverage was found for medium MU plans for both SRM and LRM. For SRM plans, dose conformity decreased with increasing MU range while the variation was reduced for LRM plans. Large MU plans reduced the inter-fraction variation for SRM and LRM.

CONCLUSIONS

We confirmed the interplay effect between target motion and beam irradiation time for CyberKnife static tracking. Plans with large MU per beam improved the GTV coverage for small motion amplitude and the inter-fraction dose variation for large motion amplitude.

Impact of the skull contour definition on Leksell Gamma Knife® Icon™ radiosurgery treatment planning

INTRODUCTION

The Gamma Knife^® planning software (TMR 10, Elekta Instruments, AB, Sweden) affords two ways of defining the skull volume, the "historical" one using manual measurements (still perform in some centers) and the new one using image-based skull contours. Our objective was to assess the potential variation of the dose delivery calculation using consecutively in the same patients the two above-mentioned techniques.

MATERIALS AND METHODS

We included in this self-case-control study, 50 patients, treated with GKRS between July 2016 and January 2017 in Lausanne University Hospital, Switzerland, distributed among four groups: convexity targets (n = 18), deep-seated targets (n = 13), vestibular schwannomas (n = 11), and trigeminal neuralgias (n = 8). Each planning was performed consecutively with the 2 skull definition techniques. For each treatment, we recorded the beam-on time (min), target volume coverage (%), prescription isodose volume (cm³), and maximal dose (Gy) to the nearest organ at risk if relevant, according to each of the 2 skull definition techniques. The image-based contours were performed using CT scan segmentation, based upon a standardized windowing for all patients.

RESULTS

The median difference in beam-on time between manual measures and image-based contouring was + 0.45 min (IQR; 0.2-0.6) and was statistically significant (p < 0.0001), corresponding to an increase of 1.28% beam-on time per treatment, when using image-based contouring. The target location was not associated with beam-on time variation (p = 0.15). Regarding target volume coverage (p = 0.13), prescription isodose volume (p = 0.2), and maximal dose to organs at risk (p = 0.85), no statistical difference was reported between the two skull contour definition techniques.

CONCLUSION

The beam-on time significantly increased using image-based contouring, resulting in an increase of the total dose delivery per treatment with the new TMR 10 algorithm. Other dosimetric parameters did not differ significantly. This raises the question of other potential impacts. One is potential dose modulation that should be performed as an adjustment to new techniques developments. The second is how this changes the biologically equivalent dose per case, as related to an increased beam on time, delivered dose, etc., and how this potentially changes the radiobiological effects of GKRS in an individual patient.

Stereotactic Radiotherapy for the Management of Refractory Ventricular Tachycardia: Promise and Future Directions

Ventricular tachycardia (VT) caused by myocardial scaring bears a significant risk of mortality and morbidity. Antiarrhythmic drug therapy (AAD) and catheter ablation remain the cornerstone of VT management, but both treatments have limited efficacy and potential adverse effects. Stereotactic body radiotherapy (SBRT) is routinely used in oncology to treat non-invasively solid tumors with high precision and efficacy. Recently, this technology has been evaluated for the treatment of VT. This review presents the basic underlying principles, proof of concept, and main results of trials and case series that used SBRT for the treatment of VT refractory to AAD and catheter ablation.

Curative management of a cardiac metastasis from lung cancer revealed by an electrical storm

Although cardiac metastases (CM) are more common than primary cardiac malignant tumors, they remain a rare localization of metastatic cancer. Until recently, CM were surgically treated as a palliative approach because of a lack of ablative solutions even for oligometastatic patients. Technological advances in radiation therapy (RT) in thoracic oncology have led to high precision delivery that enlarged the indications for stereotactic body radiotherapy (SBRT). To date, there are limited reports of cardiac SBRT for CM. Herein, we report a cardiac SBRT performed in curative intent for a lung cancer patient metastatic to the heart.

Correction to: Neoadjuvant chemoradiotherapy delivered with helical tomotherapy under daily image guidance for rectal cancer patients: efficacy and safety in a large, multi-institutional series

The article "Neoadjuvant chemoradiotherapy delivered with helical tomotherapy under daily image guidance for rectal cancer patients: efficacy and safety in a large, multi-institutional series".

[Management of refractory ventricular tachycardia using stereotactic body radiotherapy]

Stereotactic body radiotherapy (SBRT) is routinely used in oncology to treat non-invasively solid tumors with high precision and efficacy. Recently, this technology has been evaluated in the treatment of ventricular tachycardia (VT). This article presents the basic underlying principles, proofs of concept and main results of clinical studies that used SBRT for the treatment of VT.

Hepatobiliary scintigraphy allows the evaluation of short-term functional toxicity of liver stereotactic body radiotherapy: Results of a pilot study

PURPOSE

To study the potential of (99m)Tc-Mebrofenin hepatobiliary scintigraphy (HBS) in identifying the short-term variations of liver function after stereotactic body radiotherapy (SBRT) for liver cancers.

MATERIAL AND METHODS

We treated with SBRT 3 patients (pts) affected by a cholangiocarcinoma and 3 patient presenting liver metastases (3x15 Gy, 4 pts; 5x8 Gy, 1 pt; 6x5 Gy, 1 pt). All patients received HBS before and 3 months after SBRT, which were co-registered with the simulation CT-scan. Structures corresponding to isodoses from 10-90 Gy were created, with intervals of 10 Gy. Finally, the variations of the mean activity (MBq) in each isodose structure have been calculated. Then, a linear regression analysis was performed.

RESULTS

We showed a linear reduction of the activity, significantly related to the delivered dose (p<0.01), and a reduction of the perfusion of 0.78% for each delivered Gy. The linear equation has predictive value of the loss of the function of 96% (R2 = 0.9605).

CONCLUSIONS

HBS could improve treatment plans for liver SBRT, by allowing the identification of the liver function variations after SBRT and, potentially, the prediction of remnant liver function after SBRT. These preliminary results should be confirmed on long-term prospective data and larger population.

A treatment planning comparison of contemporary photon-based radiation techniques for breast cancer

Background and purpose

Adjuvant radiation therapy (RT) of the whole breast (WB) is still the standard treatment for early breast cancer. A variety of radiation techniques is currently available according to different delivery strategies. This study aims to provide a comparison of six treatment planning strategies commonly adopted for breast-conserving adjuvant RT and to use the Pareto concept in an attempt to assess the degree of plan optimization.

Materials and methods

Two groups of six left- and five right-sided cases with different dose prescriptions were involved (22 patients in total). Field-in-Field (FiF), two and four Fields static-IMRT (sIMRT-2f and sIMRT-4f), Volumetric-Modulated-Arc-Therapy (VMAT), Helical Tomotherapy (HT) and Static-Angles Tomotherapy (TomoDirect™ – TD) were planned. Dose volume constraints were taken from the RTOG protocol 1005. Pareto fronts were built for a selected case to evaluate the reliability of the plan optimization process.

Results

The best target dose coverage was observed for TD able to improve significantly (p < 0.01) the V95% in a range varying from 1.2% to 7.5% compared to other techniques. The V105% was significantly reduced up to 2% for HT (p < 0.05) although FiF and VMAT produced similar values. For the ipsilateral lung, V5Gy, V10Gy and Dmean were significantly lower than all other techniques (p < 0.02) for TD while the lowest value of V20Gy was observed for HT. The maximum dose to contralateral breast was significantly lowest for TD (p < 0.02) and for FiF (p < 0.05). Minor differences were observed for the heart in left-sided patients. Plans for all tested techniques were found to lie on their respective Pareto fronts.

Conclusions

Overall, TD provided significantly better results in terms of target coverage and dose sparing of ipsilateral lung with respect to all other evaluated techniques. It also significantly minimized dose to contralateral breast together with FiF. Pareto front analysis confirmed the reliability of the optimization for a selected case.

The Changing Paradigm for the Surgical Treatment of Large Vestibular Schwannomas

Objective  Planned subtotal resection followed by Gamma Knife surgery (GKS) in patients with large vestibular schwannoma (VS) has emerged during the past decade, with the aim of a better functional outcome for facial and cochlear function. Methods  We prospectively collected patient data, surgical, and dosimetric parameters of a consecutive series of patients treated by this method at Lausanne University Hospital during the past 8 years. Results  A consecutive series of 47 patients were treated between July 2010 and January 2018. The mean follow-up after surgery was 37.5 months (median: 36, range: 0.5-96). Mean presurgical tumor volume was 11.8 mL (1.47-34.9). Postoperative status showed normal facial nerve function (House-Brackmann I) in all patients. In a subgroup of 28 patients, with serviceable hearing before surgery and in which cochlear nerve preservation was attempted at surgery, 26 (92.8%) retained serviceable hearing. Nineteen had good or excellent hearing (Gardner-Robertson class 1) before surgery, and 16 (84.2%) retained it after surgery. Mean duration between surgery and GKS was 6 months (median: 5, range: 3-13.9). Mean residual volume as compared with the preoperative one at GKS was 31%. Mean marginal dose was 12 Gy (11-12). Mean follow-up after GKS was 34.4 months (6-84). Conclusion  Our data show excellent results in large VS management with a combined approach of microsurgical subtotal resection and GKS on the residual tumor, with regard to the functional outcome and tumor control. Longer term follow-up is necessary to fully evaluate this approach, especially regarding tumor control.

Stage III-IV Sinonasal and Nasal Cavity Carcinoma Treated with Three-Dimensional Conformal Radiotherapy

Aims and Background

To report the dosimetric data and clinical outcomes of patients with advanced neoplasm of the paranasal sinuses and nasal cavity, treated by three-dimensional conformal radiotherapy.

Methods

Between 2000 and 2005, 31 consecutive patients were treated for locally advanced tumors of paranasal sinuses and nasal cavity. The primary tumor was located as follows: maxillary sinus 15 (48.4%); ethmoid sinus 10 (32.3%); nasal cavity 6 (19.3%). The patients were separated in two groups according to the modality of treatment: group Aincluded 21 patients treated with postoperative three-dimensional conformal radiotherapy with or without chemotherapy; group B included 10 patients treated with radical three-dimensional conformal radiotherapy with or without chemotherapy. The median radiation dose to the planning target volume was 60 Gy (range, 56–63) for patients who underwent complete surgical resection and 68 Gy (range, 64–70) for those who did not have tumor resection or patients with residual disease.

Results

The median follow-up was 42 months. Five-year local tumor control and overall survival actuarial rates were 74% and 72%, respectively, in the postoperative setting, 20% and 25%, respectively, with the primary radiotherapy. Local recurrence was the most common site of failure. No patient developed radio-induced blindness; 4 patients underwent enucleation as part of radical surgery. Dosimetric data are reported.

Conclusions

The local control rate for these tumors remains low. The prognosis depends on localization, tumor stage and treatment modality. Three-dimensional conformal radiotherapy reduces the risk on optical pathways but does not modify outcome.

Minimizing a Tricky Situation in Breast Irradiation with Helical Tomotherapy

We report on a patient with breast cancer undergoing adjuvant intensity-modulated whole breast and lymph node irradiation with static angle tomotherapy (TomoDirect), who experienced a traumatic ipsilateral humeral fracture and was able to continue radiotherapy with helical tomotherapy and daily dosimetric monitoring by means of the Planned Adaptive module.

Clinical Evaluation of the Accuracy of an Invasive Frame Designed for Stereotactic Intracranial Radiosurgery Treatment with Helical Tomotherapy

Aims and background

The study focused on the evaluation of the accuracy of intracranial stereotactic radiosurgery treatments delivered with helical tomotherapy by means of the InterFix™ Radiosurgery kit.

Methods and study design

Twenty-two patients received stereotactic radiosurgery treatments with single fraction dose ranging from 13 to 20 Gy depending on diagnosis. Megavoltage computed tomography scans performed prior the treatments were analyzed in order to determine the position accuracy. For 8 selected cases, they were also performed at the end of the treatment to evaluate the intra-fraction motion.

Results

Mean setup errors and standard deviations were −1.6 ± 2.2 mm, −0.2 ± 1.2 mm, 0.4 ± 1.3 mm, 0.2 ± 0.5° for the lateral (IEC-x), longitudinal (IEC-y), vertical (IEC-z) directions and rotational variation (roll), respectively. Setup error was found to be greater than 3 mm-PTV expansion in 36% of the cases. Mean intra-fraction motion was 0.5 ± 0.7 mm, −0.3 ± 0.4 mm, 0.1 ± 0.5 mm and 0.1 ± 0.2° for the IEC-x, IEC-y, IEC-z and roll, respectively.

Conclusions

Observed intra-fraction movements of less than 1 mm suggested the use of the tested fixation device for stereotactic radiosurgery treatment on helical tomotherapy providing that the image-guidance procedure is always performed prior to treatment.

Gamma Knife radiosurgery for glossopharyngeal neuralgia: A study of 21 patients with long-term follow-up

Objective

Glossopharyngeal neuralgia (GPN) is a very rare condition, affecting the patient’s quality of life. We report our experience in drug-resistant, idiopathic GPN, treated with Gamma Knife radiosurgery (GKRS), in terms of safety and efficiency, on a very long-term basis.

Methods

The study was opened, self-controlled, non-comparative and bicentric (Marseille and Lausanne University Hospitals). Patients treated with GKRS between 2003 and 2015 (models C, 4C and Perfexion) were included. A single 4-mm isocentre was positioned in the cisternal portion of the glossopharyngeal nerve, with a targeting based both on magnetic resonance imaging (MRI) and computed tomography (CT). The mean maximal dose delivered was 81.4 ± 6.7 Gy (median = 85 Gy, range = 60–90 Gy at the 100% isodose line).

Results

Twenty-one patients (11 women, 10 men) benefited from 25 procedures. The mean follow-up period was 5.2 ± 3 years (range = 0.9–12.1 years). Seventeen (81%) were initially pain-free after GKRS. At three months, six months and one year after radiosurgery, the percentage of patients with good outcome (BNI classes I to IIIA) was 87.6%, 100% and 81.8%, respectively. Ten cases (58.8%) from the initial pain-free ones had a recurrence, after a mean period of 13.6 ± 10.4 months (range = 3.1–36.6 months). Only three patients (14.2%) had recurrences (two for each one of them) requiring further surgeries. Three patients underwent a second GKRS procedure; one case needed a third GKRS. The former procedures were performed at 7, 17, 19 and 30 months after the first one, respectively. Furthermore, two patients needed additional interventions. At last follow-up, 17 cases (80.9%) were still pain-free without medication. The actuarial pain relief without new surgery was 83%. A transient complication (paraesthesia of the edge of the tongue) was seen in one case (4.8%).

Conclusion

GKRS is a valuable, minimally invasive, surgical alternative for idiopathic GPN, with a very high short- and long-term efficacy and without permanent complications. A quality imaging, including T2 CISS/Fiesta MRI and bone CT acquisitions for good visualisation of the nerve and the other bony anatomic landmarks, is essential for targeting accuracy and successful therapy.

Acute clinical adverse radiation effects after Gamma Knife surgery for vestibular schwannomas

OBJECTIVE

Vestibular schwannomas (VSs) represent a common indication of Gamma Knife surgery (GKS). While most studies focus on the long-term morbidity and adverse radiation effects (AREs), none describe the acute clinical AREs that might appear on a short-term basis. These types of events are investigated, and their incidence, type, and outcomes are reported in the present paper.

METHODS

The included patients were treated between July 2010 and March 2016, underwent at least 6 months of follow-up, and presented with a disabling symptom during the first 6 months after GKS that affected their quality of life. The timing of appearance, as well as the type of main symptom and outcome, were noted. The prescribed dose was 12 Gy at the margin.

RESULTS

Thirty-five (22%) of 159 patients who fulfilled the inclusion criteria had acute clinical AREs. The mean followup period was 30 months (range 6–49.2 months). The mean time of appearance was 37.9 days (median 31 days; range 3–110 days). In patients with de novo symptoms, the more frequent symptoms were vertigo (n = 4; 11.4%) and gait disturbance (n = 3; 8.6%). The exacerbation of a preexisting symptom was more frequently related to hearing loss (n = 10; 28.6%), followed by gait disturbance (n = 7; 20%) and vertigo (n = 3, 8.6%). In the univariate logistic regression analysis, the following factors were statistically significant: age (p = 0.002; odds ratio [OR] 0.96), hearing at baseline by Gardner-Robertson (GR) class (p = 0.006; OR 0.21), pure tone average at baseline (p = 0.006; OR 0.97), and Koos grade at baseline (with Koos Grade I used as a reference) (for Koos Grade II, OR 0.17 and p = 0.002; for Koos Grade III, OR 0.42 and p = 0.05). The following were not statistically significant but showed a tendency toward significance: the number of isocenters (p = 0.06; OR 0.94) and the maximal dose received by the cochlea (p = 0.07; OR 0.74). Fractional polynomial regression analysis showed a nonlinear relationship between the outcome and the radiation dose rate (minimum reached at a cutoff of 2.5 Gy/minute) and the maximal vestibular dose (maximum reached at a cutoff of 8 Gy), but the small sample size precludes a detailed analysis of the former. The clinical acute AREs disappeared in 32 (91.4%) patients during the first 6 months after appearance. Permanent and somewhat disabling morbidity was found in 3 cases (1.9% from the whole series): 1 each with complete hearing loss (GR Class I before and V after), hemifacial spasm (persistent but alleviated), and dysgeusia.

CONCLUSIONS

Acute effects after radiosurgery for VS are not rare. They concern predominantly de novo vertigo and gait disturbance and the exacerbation of preexistent hearing loss. In de novo vestibular symptoms, a vestibular dose of more than 8 Gy is thought to play a role. In most cases, none of these effects are permanent, and they will ultimately improve or disappear with steroid therapy. Permanent AREs remain very rare.

Reduction of Respiratory Motion During PET/CT by Pulsatile-Flow Ventilation: A First Clinical Evaluation

Respiratory motion negatively affects PET/CT image quality and quantitation. A novel Pulsatile-Flow Ventilation (PFV) system reducing respiratory motion was applied in spontaneously breathing patients to induce sustained apnea during PET/CT.

METHODS

Four patients (aged 65 ± 14 y) underwent PET/CT for pulmonary nodule staging (mean, 11 ± 7 mm; range, 5-18 mm) at 63 ± 3 min after (18)F-FDG injection and then at 47 ± 7 min afterward, during PFV-induced apnea (with imaging lasting ≥8.5 min). Anterior-posterior thoracic amplitude, SUVmax, and SUVpeak (SUVmean in a 1-cm-diameter sphere) were compared.

RESULTS

PFV PET/CT reduced thoracic amplitude (80%), increased mean lesion SUVmax (29%) and SUVpeak (11%), decreased lung background SUVpeak (25%), improved lesion detectability, and increased SUVpeak lesion-to-background ratio (54%). On linear regressions, SUVmax and SUVpeak significantly improved (by 35% and 23%, respectively; P ≤ 0.02).

CONCLUSION

PFV-induced apnea reduces thoracic organ motion and increases lesion SUV, detectability, and delineation, thus potentially affecting patient management by improving diagnosis, prognostication, monitoring, and external-radiation therapy planning.

Radiosurgery with Helical Tomotherapy: Outcomes for Patients with One or Multifocal Brain Metastasis

To evaluate the feasibility and report the preliminary results for stereotactic radiosurgery (SRS) treatments of single or multiple brain metastases delivered with helical tomotherapy (HT) by means of the InterFix™ Radiosurgery kit. Between September 2010 and August 2012, thirty patients underwent SRS for treatment of 46 brain metastases with a median prescription dose of 20 Gy (range 15-21 Gy). Clinical response was assessed with 2-3 month intervals by magnetic resonance imaging (MRI). Dose distribution indexes were computed and compared with published data for SRS performed with dedicated machines. After a median follow-up of 14 months (range 4-31) the estimated overall survival (OS) rate was 70% at 6 months, 60% at 12 months and 44% at 18 months. Local control (LC) was 72% at 6 months, 65% at 12 months and 50% at 18 months. Acute toxicity as headache and epileptic crisis occurred in only two patients. The mean values of conformity, homogeneity and gradient score indexes were 1.36, 1.04 and 50 respectively. HT-SRS for single or multiple brain metastases appears a reliable technique with encouraging clinical outcomes and competitive dosimetrical results.

Palliative radiotherapy for painful bone metastases from solid tumors delivered with static ports of tomotherapy (TomoDirect): feasibility and clinical results

PURPOSE

To evaluate the feasibility and response to palliative radiotherapy delivered with static ports of tomotherapy--TomoDirect (TD) in patients affected with painful bone metastases from solid tumors.

METHODS

A prospective cohort of 130 patients (185 osseous lesions) was treated between 2010 and 2013 with TD. Three fractionation schedules were employed according to clinical decision-making (3 Gy × 10; 4 Gy × 5; 8 Gy × 1). Pain response was investigated at 2 weeks and 2 months (for evaluable patients). The Numeric Rating Scale (NRS-11) was used to assess pain. Response rates to radiotherapy were calculated following the criteria of the International Bone Metastases Consensus Group (IBMCG), accounting for the use of concomitant analgesics (response: complete or partial; non-response: stable pain, pain progression or "other"). Analgesic consumption was recalculated into the daily oral morphine-equivalent dose (OMED).

RESULTS

Most of the patients had 1-2 bone metastases (91); those with multiple lesions mostly had a metachronous presentation (60%). Synchronous lesions were mainly approached with multiple plans (63%). Most treatments employed 3-4 fields (77%). Treatment times ranged from 255 to 939 s depending on fractionation, fields, and target lesions number. At 2 weeks, the median self-reported worst pain decreased significantly as median oral morphine-equivalent dose regardless of fractionation used. The response rate according to the IBMCG-based response categories ranged from 45 to 55%. Pain relief duration seems (response at 2 months) slightly inferior with the single fraction approach, with a higher re-treatment rate. At 2 weeks, the median self-reported worst pain and OMED significantly decreased regardless of fractionation (response rate: 49-55%). Pain relief decreased at 2 months, especially for single fraction (higher re-treatment rate).

CONCLUSION

TD is a valid option to deliver palliative radiotherapy for painful bone metastases from solid tumors.

Minimizing a tricky situation in breast irradiation with helical tomotherapy

We report on a patient with breast cancer undergoing adjuvant intensity-modulated whole breast and lymph node irradiation with static angle tomotherapy (TomoDirect), who experienced a traumatic ipsilateral humeral fracture and was able to continue radiotherapy with helical tomotherapy and daily dosimetric monitoring by means of the Planned Adaptive module.

Modeling acute urinary toxicity after radiotherapy for prostate cancer

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Background: DUE-01 is a multi-centric observational study aimed at developing predictive models of genito-urinary toxicity and erectile dysfunction for prostate cancer patients treated with conventional (1.8-2Gy/fr, CONV) or moderate hypofractionation (2.5-2.7Gy/fr, HYPO). Current analysis focused on modelling the relationship between the risk of IPSS≥15 (IPSS15end) at the end of radiotherapy and clinincal/dosimetric risk factors. Methods: Planning data and relevant clinical factors were prospectively collected, including DVH/DSH referred to the whole treatment and to the weekly delivered dose (DVHw/DSHw). Best discriminating DVH/DSH parameters were selected by the differences between patients with/without IPSS15end=1 (t-test). Bootstrap variable selection techniques (300 resamples) in the framework of logistic backward feature selection was used to improve model building (El Naqa, IJROBP 2006). Graphical and quantitative analyses of the variable selection process applied to bootstrap data replicates was used to avoid underfitting/overfitting and to assess the final multivariable model. Results: 247 patients were available (CONV:116, HYPO:131). Seventy one out of 247 (28.7%) reported IPSS15end=1. The most predictive dosimetric tools were the absolute weekly delivered dose (DSHw and DVHw). DSHw and DVHw were alternatively inserted in the bootstrap variable selection flow, together with clinical risk factors. Due to the number of events, a logistic model containing six variables was accepted On the basis of observed frequency of variables in the top six positions, a model including basal IPSS (median OR=1.22, p=0.00001), use of anti-hypertensives (median OR=2.7, p=0.01), absolute bladder surface receiving more than 10.5 Gy/week (s10.5w, median OR=1.16, p=0.0001), and s12.5w (median OR=1.07, p=0.005), was choosen. AUC of this model was 0.80. Silmilar results were obtained when using DVHw. Conclusions: Basal IPSS, use of anti-hypertensive drugs, s10.5w/v10.5w and s12.5w/v12.5w are the main predictors of IPSS>=15 at the end of radiotherapy Bootstrap variable selection technique gives the modeler more insight into the importance and stability of the different variables selected and allows development of more robust models

Exposures from nuclear medicine diagnostic procedures: the dose impact on the Aosta Valley population

The present work evaluates the per-procedure, annual collective and per-capita effective doses to the Aosta Valley region population from nuclear medicine (NM) examinations performed from 2005 to 2011 at the regional NM department. Based on its demographical and socioeconomics characteristics, this area can be considered as representative of the level I countries, as defined by the United Nations Scientific Committee on the Effects of Atomic Radiation. The NM per-procedures effective doses were within the range of 0.018-35 mSv. A steady frequency per 10 000 inhabitants has been observed, together with a decrease for thyroid and whole-body bone scintigraphy. Myocardial and bone scintigraphy studies were the major contributors to the total collective effective dose. The mean annual collective and per-capita effective doses to the population were 15 man Sv y(-1) and 120 µSv y(-1), respectively. The NM contribution to the total per-capita effective dose accounts for 5.9 % of that due to the medical ionising radiation examinations overall.

Intensity-modulated adjuvant whole breast radiation delivered with static angle tomotherapy (TomoDirect): a prospective case series

PURPOSE

To report the 2-year outcomes of whole breast intensity-modulated radiotherapy (IMRT) after conserving surgery for early breast cancer (EBC) delivered with static angle tomotherapy (TomoDirect) (TD).

METHODS

A prospective cohort of 120 EBC patients underwent whole breast IMRT with TD between 2010 and 2012. Radiation was delivered to a conventionally fractionated whole breast total dose of 50 Gy with TD, followed by a sequential conventionally fractionated tumor bed boost dose of 10-16 Gy with helical tomotherapy (HT). Clinical endpoints include acute and late toxicity, cosmesis, quality of life and local control.

RESULTS

Median follow-up was 24 months (range 12-36 months); maximum detected acute skin toxicity was G0 22 %; G1 63 %; G2 12 % and G3 3 %. Predictors of acute dermatitis were as follows: volume of the whole breast minus boost volume receiving 105, 110 and 115 % of prescription dose, whole breast and boost volume, breast thickness and soft tissue thickness. Late skin toxicity was mild with no >G2 events. Cosmesis was good/excellent in 91.7 % of patients and fair/poor in 8.3 %. Quality of life was preserved over time, but for fatigue, transiently increased.

CONCLUSION

Adjuvant whole breast IMRT delivered sequentially with both TD and HT provides consistent clinical results. An observed unintended excessive dose outside the tumor bed might increase acute toxicity and eventually affect long-term clinical endpoints. The incorporation of the boost dose within the whole breast phase employing a simultaneous integrated boost (SIB) approach might mitigate this issue.