Efficiency and Accuracy Evaluation of Multiple Diffusion-Weighted MRI Techniques Across Different Scanners.

BACKGROUND: The choice between different diffusion-weighted imaging (DWI) techniques is difficult as each comes with tradeoffs for efficient clinical routine imaging and apparent diffusion coefficient (ADC) accuracy. PURPOSE: To quantify signal-to-noise-ratio (SNR) efficiency, ADC accuracy, artifacts, and distortions for different DWI acquisition techniques, coils, and scanners. STUDY TYPE: Phantom, in vivo intraindividual biomarker accuracy between DWI techniques and independent ratings. POPULATION/PHANTOMS: NIST diffusion phantom. 51 Patients: 40 with prostate cancer and 11 with head-and-neck cancer at 1.5 T FIELD STRENGTH/SEQUENCE: Echo planar imaging (EPI): 1.5 T and 3 T Siemens; 3 T Philips. Distortion-reducing: RESOLVE (1.5 and 3 T Siemens); Turbo Spin Echo (TSE)-SPLICE (3 T Philips). Small field-of-view (FOV): ZoomitPro (1.5 T Siemens); IRIS (3 T Philips). Head-and-neck and flexible coils. ASSESSMENT: SNR Efficiency, geometrical distortions, and susceptibility artifacts were quantified for different b-values in a phantom. ADC accuracy/agreement was quantified in phantom and for 51 patients. In vivo image quality was independently rated by four experts. STATISTICAL TESTS: QIBA methodology for accuracy: trueness, repeatability, reproducibility, Bland-Altman 95% Limits-of-Agreement (LOA) for ADC. Wilcoxon Signed-Rank and student tests on P < 0.05 level. RESULTS: The ZoomitPro small FOV sequence improved b-image efficiency by 8%-14%, reduced artifacts and observer scoring for most raters at the cost of smaller FOV compared to EPI. The TSE-SPLICE technique reduced artifacts almost completely at a 24% efficiency cost compared to EPI for b-values ≤500 sec/mm2 . Phantom ADC 95% LOA trueness were within ±0.03 × 10-3 mm2 /sec except for small FOV IRIS. The in vivo ADC agreement between techniques, however, resulted in 95% LOAs in the order of ±0.3 × 10-3 mm2 /sec with up to 0.2 × 10-3 mm2 /sec of bias. DATA CONCLUSION: ZoomitPro for Siemens and TSE SPLICE for Philips resulted in a trade-off between efficiency and artifacts. Phantom ADC quality control largely underestimated in vivo accuracy: significant ADC bias and variability was found between techniques in vivo. LEVEL OF EVIDENCE: 3 TECHNICAL EFFICACY STAGE: 2.

BioPro-RCMI-1505 trial: multicenter study evaluating the use of a biodegradable balloon for the treatment of intermediate risk prostate cancer by intensity modulated radiotherapy; study protocol.

BACKGROUND: Prospective trials have demonstrated the advantage of dose-escalated radiotherapy for the biochemical and clinical control of intermediate risk prostate cancer. Dose escalation improves outcomes but increases risks of urinary and bowel toxicity. Recently the contribution of "spacers" positioned in the septum between the rectum and the prostate could improve the functional results of intensity modulated radiation therapy (IMRT). To date most of the evaluated devices were polyethylen glycol (PEG) and hyaluronic acid (HA). Men on the Spacer arm had decreased bowel toxicity and less decline in both urinary and bowel quality of life as compared to Control men in a randomized trial. METHODS: This is an interventional, multi-center study to evaluate the use of biodegradable inflatable balloon for patients with intermediate risk prostate cancer treated by IMRT (74 to 80 Gy, 2 Gy/fraction) with daily image guided radiotherapy. DISCUSSION: This multicenter prospective study will yield new data regarding dosimetric gain and implantation stages of Bioprotect balloon. Acute and late toxicities and quality of life will be registered too. TRIAL REGISTRATION: NCT02478112 , date of registration: 15/06/2015.

Preoperative chemoradiation with paclitaxel-carboplatin or with fluorouracil-oxaliplatin-folinic acid (FOLFOX) for resectable esophageal and junctional cancer: the PROTECT-1402, randomized phase 2 trial.

BACKGROUND: Often curative treatment for locally advanced resectable esophageal or gastro-esophageal junctional cancer consists of concurrent neoadjuvant radiotherapy and chemotherapy followed by surgery. Currently, one of the most commonly used chemotherapy regimens in this setting is a combination of a fluoropyrimidin and of a platinum analogue. Due to the promising results of the recent CROSS trial, another regimen combining paclitaxel and carboplatin is also widely used by European and American centers. No clinical study has shown the superiority of one treatment over the other. The objective of this Phase II study is to clarify clinical practice by comparing these two chemotherapy treatments. Our aim is to evaluate, in operable esophageal and gastro-esophageal junctional cancer, the complete resection rate and severe postoperative morbidity rate associated with these two neoadjuvant chemotherapeutic regimens (carboplatin-paclitaxel or fluorouracil-oxaliplatin-folinic acid) when each is combined with the radiation regime utilized in the CROSS trial. METHODS/DESIGN: PROTECT is a prospective, randomized, multicenter, open arms, phase II trial. Eligible patients will have a histologically confirmed adenocarcinoma or squamous cell carcinoma and be treated with neoadjuvant radiochemotherapy followed by surgery for stage IIB or stage III resectable esophageal cancer. A total of 106 patients will be randomized to receive either 3 cycles of FOLFOX combined to concurrent radiotherapy (41.4 Grays) or carboplatin and paclitaxel with the same radiation regimen, using a 1:1 allocation ratio. DISCUSSION: This ongoing trial offers the unique opportunity to compare two standards of chemotherapy delivered with a common regimen of preoperative radiation, in the setting of operable locally advanced esophageal or gastro-esophageal junctional tumors. TRIAL REGISTRATION: NCT02359968 (ClinicalTrials.gov) (registration date: 9 FEB 2015), EudraCT: 2014-000649-62 (registration date: 10 FEB 2014).

Inverse treatment planning for spinal robotic radiosurgery: an international multi-institutional benchmark trial.

Stereotactic radiosurgery (SRS) is the accurate, conformal delivery of high-dose radiation to well-defined targets while minimizing normal structure doses via steep dose gradients. While inverse treatment planning (ITP) with computerized optimization algorithms are routine, many aspects of the planning process remain user-dependent. We performed an international, multi-institutional benchmark trial to study planning variability and to analyze preferable ITP practice for spinal robotic radiosurgery. 10 SRS treatment plans were generated for a complex-shaped spinal metastasis with 21 Gy in 3 fractions and tight constraints for spinal cord (V14Gy < 2 cc, V18Gy < 0.1 cc) and target (coverage > 95%). The resulting plans were rated on a scale from 1 to 4 (excellent-poor) in five categories (constraint compliance, optimization goals, low-dose regions, ITP complexity, and clinical acceptability) by a blinded review panel. Additionally, the plans were mathemati-cally rated based on plan indices (critical structure and target doses, conformity, monitor units, normal tissue complication probability, and treatment time) and compared to the human rankings. The treatment plans and the reviewers' rankings varied substantially among the participating centers. The average mean overall rank was 2.4 (1.2-4.0) and 8/10 plans were rated excellent in at least one category by at least one reviewer. The mathematical rankings agreed with the mean overall human rankings in 9/10 cases pointing toward the possibility for sole mathematical plan quality comparison. The final rankings revealed that a plan with a well-balanced trade-off among all planning objectives was preferred for treatment by most par-ticipants, reviewers, and the mathematical ranking system. Furthermore, this plan was generated with simple planning techniques. Our multi-institutional planning study found wide variability in ITP approaches for spinal robotic radiosurgery. The participants', reviewers', and mathematical match on preferable treatment plans and ITP techniques indicate that agreement on treatment planning and plan quality can be reached for spinal robotic radiosurgery.

Safety of adjuvant intensity-modulated postoperative radiation therapy in endometrial cancer: Clinical data and dosimetric parameters according to the International Commission on Radiation Units (ICRU) 83 report.

AIM: To report a single-institution experience using postoperative pelvic Intensity Modulation Radiation Therapy (IMRT) using tomotherapy accelerators (TA) in postoperative endometrial cancer (EC) regarding ICRU 83 recommendations. BACKGROUND: IMRT in gynecological malignancies provides excellent dosimetric data, lower rates of adverse events and clinical data similar to historical series. MATERIAL AND METHODS: Seventy-six patients with EC were postoperatively treated with adjuvant IMRT using TA. The IMRT dose was 45 Gy for patients without positive lymph nodes and Type I histology and 50.4 Gy for patients with positive lymph nodes and/or type II histology. RESULTS: With a median follow-up of 29 months, the 12- and 24-month Overall Survival (OS) and Disease-Free Survival (DFS) were 96%, 93%, 87%, and 74%, respectively. Age of less than 60 years was associated with better OS (HR: 8.9; CI: 1.1-68) and DFS (HR: 3.5; CI: 1.2-10.2). Patients with Type II and Type I Grade III histology had a worse OS (HR: 3.3; CI: 1.1-11). Five women (6.6%) presented in-field local vaginal recurrence, 2 (2.6%) presented non-in-field vaginal recurrence, 4 (5.2%) presented pelvic node and distant recurrence and 11 (14.4%) presented only distant metastases. One patient stopped radiation treatment due to Grade III acute diarrhea. No Grade III late toxicity was observed. Planning Target Volume (PTV) coverage showed mean D2, D50, D95, and D98 of 51.64-46.23 Gy, 49.49-44.97 Gy, 48.62-43.96 Gy, and 48.47-43.58 Gy for patients who received 45 and 50.4 Gy, respectively. CONCLUSIONS: IMRT with TA in postoperative EC shows excellent conformity and homogeneity of PTV dose. Without Grade III late toxicity, data from this cohort demonstrated the utility of IMRT.

Intensity modulated arc therapy in bilaterally irradiated head and neck cancer: a comparative and prospective multicenter planning study.

A dosimetric comparison was made of Helical Tomotherapy (HT) and Rapid'Arc(®) (RA) in 115 patients with head and neck carcinoma included in a prospective and multicentric study. HT and RA provided highly conformal plans that easily complied with dose volume constraints for organs at risk. HT reduced high doses to the planning target volumes (PTVs) compared to RA and provided a more homogeneous dose distribution but with an increased Non Tumoral Integral Dose (NTID) than RA. However, the clinical consequences of these dosimetric advantages and disadvantages need further investigation.

Extreme hypofractionated stereotactic radiotherapy for localized prostate Cancer: Efficacy and late urinary toxicity according to transurethral resection of the prostate history.

Background and purpose: Extreme hypofractionated stereotactic body radiotherapy (SBRT) is a therapeutic alternative for localized low- or intermediate-risk prostate cancer. Despite the availability of several studies, the toxicity profile of SBRT has not been comprehensively described. This real-world evidence study assessed the efficacy and toxicities associated with this regimen, and potential prognosis factors for genitourinary toxicities. Materials and methods: This retrospective study included 141 consecutive patients with localized prostatic adenocarcinoma treated with CyberKnife™ SBRT, as primary irradiation, at the Oscar Lambret Center between 2010 and 2020. The prescribed dose was 36.25 Gy in 5 fractions. Acute and late toxicities were graded according to the CTCAE (version 5.0). Biochemical recurrence-free survival (bRFS) and overall survival (OS) were estimated using the Kaplan-Meier method. The cumulative incidence of biochemical recurrence (cBR) was estimated using the Kalbfleisch-Prentice method. Results: Among the included patients, 13.5 % had a history of transurethral resection of the prostate (TURP). The median follow-up was 48 months. At 5 years, bRFS, cBR, and OS were 72 % (95 %CI: 61-81), 7 % (95 %CI: 3-14), and 82 % (95 %CI: 73-89), respectively. Twenty-nine patients experienced at least one late toxicity of grade ≥ 2; genitourinary (N = 29), including 3 cases of chronic hematuria, and/or gastrointestinal (N = 1). The cumulative incidence of late urinary toxicity of grade ≥ 2 was 20.6 % at 5 years (95 %CI: 13.9-28.1). Multivariate analysis revealed that a history of TURP was significantly associated with late urinary toxicity of grade ≥ 2, after adjusting for clinical target volume (Odds Ratio = 3.06; 95%CI: 1.05-8.86; P = 0.04). Conclusion: Extreme hypofractionated SBRT is effective for localized prostate cancer with a low risk of late toxicity. A history of TURP is associated with a higher risk of late urinary toxicity. These findings may contribute to the optimal management of patients treated with this regimen, particularly those with a history of TURP.

SHARE: a French multicenter phase III trial comparing accelerated partial irradiation versus standard or hypofractionated whole breast irradiation in breast cancer patients at low risk of local recurrence.

The standard treatment for breast cancer patients at low risk of recurrence is based on conservative surgery followed by radiation therapy delivered to the whole breast. The accelerated partial breast irradiation (APBI) concept, developed more than 15 years ago, could be an option in selected patients. However, the ideal patient profile for APBI is still not clearly identified. Recent reports from the American Society for Radiation Oncology (ASTRO) and the Groupe Européen de Curiethérapie-European Society for Therapeutic Radiology and Oncology (GEC-ESTRO) have suggested selection criteria for "suitable patients" who could receive APBI outside of clinical trials. Currently, there are 6 ongoing phase III trials. All are characterized by a significant heterogeneity regarding inclusion criteria and stratification factors. The French UNICANCER trial (SHARE; ClinicalTrials.gov identifier NCT01247233) will randomize 2,800 patients in 3 arms: APBI (1 week) using 3-dimensional (3D) conformal radiotherapy, standard radiotherapy (6.5 weeks), and hypofractionated radiotherapy (3 weeks). In this article, we review the reported retrospective studies as well as older randomized trials. We will also describe the differences between the 6 ongoing phase III trials and the particularities of the French SHARE trial.

Evaluation of surface image guidance and Deep inspiration Breath Hold technique for breast treatments with Halcyon.

PURPOSE: To evaluate the accuracy/agreement of a three-camera Catalyst Surface Guided Radiation Therapy (SGRT) system on a closed-gantry Halcyon for Free-Breathing (FB) and Deep Inspiration Breath Hold (DIBH) breast-only treatments. METHODS: The SGRT positioning agreement with Halcyon couch and cone-beam computed tomography (CBCT) was evaluated on phantom and by evaluation of 2401 FB and 855 DIBH breast-only treatment sessions. The DIBH agreement was evaluated using a programmable moving support. Dose agreement was evaluated for manual SGRT-assisted beam interruption and Halcyon arc beam interruption. RESULTS: Geometrical phantom agreement was < 0.4 mm. Couch and SGRT agreement for an anthropomorphic phantom resulted in 95% limits of agreement in Right-Left/Feet-Head/Posterior-Anterior (RL/FH/PA) directions of respectively ± 0.4/0.8/0.5 mm and ± 1.1/1.1/0.6 mm in the virtual and real isocenter. FB-SGRT-assisted patient positioning compared to CBCT positioning resulted in RL/FH/PA systematic differences of -0.1/0.1/2.0 mm with standard deviations of 2.7/2.8/2.4 mm. This mean systematic difference had three origins: a) couch sag/isocenter difference of ≤ 0.5 mm. b) Average reconstructed FB-CBCT images do not visually represent the average respiratory position. c) CBCT-based positioning focused on the inner thoracic interface, which can introduce a mean positioning difference between SGRT and CBCT. Manual SGRT-assisted beam interruption and arc interruptions resulted in mean gamma passing rates > 97% (0.5%/0.5 mm) and mean absolute differences < 0.3%. CONCLUSIONS: Accuracy was comparable with breast-only C-arm SGRT techniques, with different tradeoffs. Depending on the patient's morphology, real-time tracking accuracy in the real isocenter can be reduced. This study demonstrates possible discordances between SGRT and CBCT positioning for breast.

Achievable Dosimetric Constraints in Stereotactic Reirradiation for Recurrent Prostate Cancer.

PURPOSE: Stereotactic body radiation therapy has been proposed as a salvage treatment for recurrent prostate cancer after irradiation. One crucial issue is choosing appropriate dose-volume constraints (DVCs) during planning. The objectives of this study were to (1) quantify the proportion of patients respecting the DVCs according to the Urogenital Tumor Study Group GETUG-31 trial, testing 36 Gy in six fractions, (2) explain geometrically why the DVCs could not be respected, and (3) propose the most suitable DVCs. METHODS AND MATERIALS: This retrospective dosimetric analysis included 141 patients treated for recurrent prostate cancer with Cyberknife (Accuray), according to GETUG-31 DVCs: V95% ≥ 95% for the planning target volume (PTV), V12Gy < 20% and V27Gy < 2 cc for the rectum, and V12Gy < 15% and V27Gy < 5 cc for the bladder. The percentage of patients not respecting the DVCs was quantified. Correlations between the DVCs and anatomic structures were examined. New DVCs were proposed. RESULTS: Only 19% of patients respected all DVCs, with a mean PTV of 18.5 cc (range, 3-48 cc), although the mean PTV was 40.5 cc (range, 3-174 cc) in the whole series. A total of 98% of the patients with a clinical target volume (CTV)/prostate ratio >0.5 could not respect the DVCs in the organs at risk. The target coverage and organ-at-risk sparing decreased significantly with increase in the values of PTV, CTV, CTV/prostate ratio, the overlapping volume between the PTV and bladder wall and between the PTV and rectal wall. Threshold values of PTV, >20 cc and 40 cc, allowed for the PTV and bladder DVCs, respectively. To improve DVC respect in case of large target volume, we proposed the following new DVCs: V12Gy < 25% and 25% and V27Gy < 2 cc and 5 cc for the rectum and bladder, respectively. CONCLUSIONS: GETUG-31 DVCs are achievable only for small target volumes (CTV more than half of the prostate). For a larger target volume, new DVCs have been proposed.

IMRT in the treatment of locally advanced or inoperable NSCLC in the pre-durvalumab era: clinical outcomes and pattern of relapses, experience from the Oscar Lambret Center.

Background: Intensity-modulated conformal radiotherapy (IMRT) has become the technique of choice for the treatment of locally advanced or inoperable non-small cell lung cancer (NSCLC). Nevertheless, this technique presents dosimetric uncertainties, particularly in treating moving targets such as pulmonary neoplasms. Moreover, it theoretically increases the risk of isolated nodal failure (INF) due to reduced incidental irradiation. Objective: The objective of this study was to evaluate the efficacy and safety of IMRT in patients with inoperable NSCLC and to describe the pattern of relapses. Methods: Patients with locally advanced NSCLC treated with radiotherapy and chemotherapy between 2015 and 2018 at the Oscar Lambret Center were retrospectively included in the study. Overall and progression-free survival were estimated using the Kaplan-Meier method. The cumulative incidence of the different components of relapse was estimated using the Kalbfleisch and Prentice method. Prognostic factors for relapse/death were investigated using the Cox model. A comparison with literature data was performed using a one-sample log-rank test. Results: Seventy patients were included, and 65 patients (93%) had stage III disease. All the patients received chemotherapy, most frequently with cisplatin and navelbine. The dose received was 66 Gy administered in 33 fractions. The median follow-up and survival were 49.1 and 39.1 months, respectively. A total of 35 deaths and 43 relapses, including 29 with metastatic components, were reported. The overall survival rates at 1 and 2 years were 80.2% (95% confidence interval 68.3%-88.0%) and 67.2% (95% confidence interval 54.2%-77.3%), respectively. Locoregional relapse was observed in 14 patients, including two INF, one of which was located in the lymph node area adjacent to the clinical target volume. Median relapse-free survival was 15.2 months. No variable was statistically associated with the risk of relapse/death in multivariate analysis. Seven patients (10%) experienced grade 3 or higher toxicity. Conclusion: The use of IMRT for locally advanced or inoperable NSCLC led to favorable long-term clinical outcomes. The rate of locoregional relapse, particularly isolated lymph node failure, was low and comparable with that of the three-dimensional radiotherapy series, as was the rate of early and late toxicities.

A Multicenter Phase 2 Study of Ultrahypofractionated Stereotactic Boost After External Beam Radiotherapy in Intermediate-risk Prostate Carcinoma: A Very Long-term Analysis of the CKNO-PRO Trial.

Background: Genitourinary (GU) or gastrointestinal (GI) complications and tumor relapse can occur in the long term after radiotherapy for prostate cancer. Objective: To assess the late tolerance and relapse-free survival (RFS) in patients undergoing hypofractionated stereotactic boost therapy after external beam radiotherapy (EBRT) for intermediate-risk prostate cancer. Design setting and participants: Seventy-six patients with intermediate-risk prostate carcinoma between August 2010 and April 2013 were included. The first course delivered a dose of 46 Gy by conventional fractionation; the second course was a boost of 18 Gy (3 × 6 Gy) within 10 d. Outcome measurements and statistical analysis: GU and GI toxicities were evaluated as the primary outcomes. The secondary outcomes were overall survival and RFS. The cumulative incidence of toxicity was calculated using a competing-risk approach. Overall survival and RFS were estimated using the Kaplan-Meier method. Results and limitations: The median follow-up period was 88 mo (range, 81-99 mo). Sixty (79%) patients were treated with the CyberKnife and 16 (21%) using a linear accelerator. The cumulative incidences of GU and GI grade ≥2 toxicities at 120 mo were 1.4% (95% confidence interval [CI]: 0.1-6.6%) and 11.0% (95% CI: 5.1-19.4%), respectively. The overall survival and RFS rates at 8 yr were 89.1% (95% CI: 77-95%) and 76.9% (95% CI: 63.1-86.1), respectively. Conclusions: A very long follow-up showed low GU and GI toxicities after a hypofractionated stereotactic boost after EBRT for intermediate-risk prostate cancer. Dose escalation of the boost delivered by hypofractionated radiation therapy appears safe for use in future trials. Patient summary: We found low toxicity and good survival rates after a short and high-precision boost after external beam radiotherapy for intermediate-risk prostate cancer, with a long-term follow-up of 88 mo. This long-term treatment is safe and should be considered in future trials.

Influence of the Hypersensitivity to Low Dose Phenomenon on the Tumor Response to Hypofractionated Stereotactic Body Radiation Therapy.

Stereotactic body radiation therapy (SBRT) has made the hypofractionation of high doses delivered in a few sessions more acceptable. While the benefits of hypofractionated SBRT have been attributed to additional vascular, immune effects, or specific cell deaths, a radiobiological and mechanistic model is still needed. By considering each session of SBRT, the dose is divided into hundreds of minibeams delivering some fractions of Gy. In such a dose range, the hypersensitivity to low dose (HRS) phenomenon can occur. HRS produces a biological effect equivalent to that produced by a dose 5-to-10 times higher. To examine whether HRS could contribute to enhancing radiation effects under SBRT conditions, we exposed tumor cells of different HRS statuses to SBRT. Four human HRS-positive and two HRS-negative tumor cell lines were exposed to different dose delivery modes: a single dose of 0.2 Gy, 2 Gy, 10 × 0.2 Gy, and a single dose of 2 Gy using a non-coplanar isocentric minibeams irradiation mode were delivered. Anti-γH2AX immunofluorescence, assessing DNA double-strand breaks (DSB), was applied. In the HRS-positive cells, the DSB produced by 10 × 0.2 Gy and 2 Gy, delivered by tens of minibeams, appeared to be more severe, and they provided more highly damaged cells than in the HRS-negative cells, suggesting that more severe DSB are induced in the "SBRT modes" conditions when HRS occurs in tumor. Each SBRT session can be viewed as hyperfractionated dose delivery by means of hundreds of low dose minibeams. Under current SBRT conditions (i.e., low dose per minibeam and not using ultra-high dose-rate), the response of HRS-positive tumors to SBRT may be enhanced significantly. Interestingly, similar conclusions were reached with HRS-positive and HRS-negative untransformed fibroblast cell lines, suggesting that the HRS phenomenon may also impact the risk of post-RT tissue overreactions.

Radiation-induced lung injury after breast cancer treatment: incidence in the CANTO-RT cohort and associated clinical and dosimetric risk factors.

Purpose: Radiation-induced lung injury (RILI) is strongly associated with various clinical conditions and dosimetric parameters. Former studies have led to reducing radiotherapy (RT) doses to the lung and have favored the discontinuation of tamoxifen during RT. However, the monocentric design and variability of dosimetric parameters chosen have limited further improvement. The aim of our study was to assess the incidence of RILI in current practice and to determine clinical and dosimetric risk factors associated with RILI occurrence. Material and methods: Data from 3 out of the 10 top recruiting centers in CANTO-RT, a subset of the CANTO prospective longitudinal cohort (NCT01993498), were retrospectively analyzed for RILI occurrence. This cohort, which recruited invasive cT0-3 cN0-3 M0 breast cancer patients from 2012 to 2018, prospectively recorded the occurrence of adverse events by questionnaires and medical visits at the end of, and up to 60 months after treatment. RILI adverse events were defined in all patients by the association of clinical symptoms and compatible medical imaging. Results: RILI was found in 38/1565 (2.4%) patients. Grade II RILI represented 15/38 events (39%) and grade III or IV 2/38 events (6%). There were no grade V events. The most frequently used technique for treatment was 3D conformational RT (96%). In univariable analyses, we confirmed the association of RILI occurrence with pulmonary medical history, absence of cardiovascular disease medical history, high pT and pN, chemotherapy use, nodal RT. All dosimetric parameters were highly correlated and had close predictive value. In the multivariable analysis adjusted for chemotherapy use and nodal involvement, pulmonary medical history (OR=3.05, p<0.01) and high V30 Gy (OR=1.06, p=0.04) remained statistically significant risk factors for RILI occurrence. V30 Gy >15% was significantly associated with RILI occurrence in a multivariable analysis (OR=3.07, p=0.03). Conclusion: Our study confirms the pulmonary safety of breast 3D RT in CANTO-RT. Further analyses with modern radiation therapy techniques such as IMRT are needed. Our results argue in favor of a dose constraint to the ipsilateral lung using V30 Gy not exceeding 15%, especially in patients presenting pulmonary medical history. Pulmonary disease records should be taken into account for RT planning.

The Safety and Efficacy of Salvage Stereotactic Radiation Therapy in Patients with Intraprostatic Tumor Recurrence After Previous External Radiation Therapy: Phase 1 Results from the GETUG-AFU 31 Study.

BACKGROUND: There is no consensus on the best local salvage treatment for prostate cancer recurrence after primary external beam radiotherapy. Prospective data on stereotactic body radiation therapy (SBRT) are very scarce. OBJECTIVE: To determine the optimal dose regimen for salvage SBRT. DESIGN, SETTING, AND PARTICIPANTS: The present report concerns the phase 1 part of the GETUG-AFU 31 multicenter open-label study. The main inclusion criteria were histologically proven biochemical recurrence, clinical stage T1-T2 upon relapse, multiparametric magnetic resonance imaging data, prostate-specific antigen (PSA) level ≤10 ng/ml prior to salvage SBRT, PSA doubling time >10 mo, and an International Prostate Symptom Score of ≤12. INTERVENTION: Five or six fractions of 6 Gy were delivered using focal SBRT. OUTCOME MEASUREMENTS AND STATISTICAL ANALYSIS: Dose-limiting toxicity (DLT) was defined as grade ≥3 gastrointestinal or genitourinary tract toxicity, or any grade 4 toxicity (according to the National Cancer Institute Common Terminology Criteria for Adverse Events version 4.03) occurring in the first 18 wk following treatment initiation. A time-to-event continual reassessment method was used to select the dose regimen. RESULTS AND LIMITATIONS: Twenty-one patients were treated (median [interquartile range] age: 76.8 yr [72.2-80.8]), including 12 at 6 × 6 dose level. No DLT was observed. The acute grade 2 genitourinary tract toxicity rate was 19%. With a median follow-up of 12.3 mo, the estimated cumulative incidence of late grade 2 genitourinary toxicity was 41.2% (95% confidence interval: 18.1-63.1%). No grade >2 genitourinary toxicity and no grade ≥2 gastrointestinal toxicity were reported. All treated patients were alive and relapse free at the last follow-up. CONCLUSIONS: A 6 × 6 Gy dose regimen was selected for our phase 2 study of salvage SBRT. With a short follow-up period, the level of toxicity appears to be acceptable. PATIENT SUMMARY: There is no consensus on the best local treatment for patients with local relapse after radiotherapy for prostate cancer. Prospective data are very scarce. Our early phase trial allowed us to recommend six fractions of 6 Gy using high-precision radiotherapy for further studies.

Practical and technical key challenges in head and neck adaptive radiotherapy: The GORTEC point of view.

Anatomical variations occur during head and neck (H&N) radiotherapy (RT) treatment. These variations may result in underdosage to the target volume or overdosage to the organ at risk. Replanning during the treatment course can be triggered to overcome this issue. Due to technological, methodological and clinical evolutions, tools for adaptive RT (ART) are becoming increasingly sophisticated. The aim of this paper is to give an overview of the key steps of an H&N ART workflow and tools from the point of view of a group of French-speaking medical physicists and physicians (from GORTEC). Focuses are made on image registration, segmentation, estimation of the delivered dose of the day, workflow and quality assurance for an implementation of H&N offline and online ART. Practical recommendations are given to assist physicians and medical physicists in a clinical workflow.

Economic evaluation and budget-impact of accelerated partial breast irradiation (APBI) versus standard or hypofractionated whole breast irradiation (WBI) in postmenopausal women with early-stage breast cancer. Results from the French SHARE randomized trial.

PURPOSE: This economic evaluation reports the incremental cost-utility ratio and national budget impact in France of accelerated partial breast irradiation (APBI) vs standard or hypofractionated whole breast irradiation (WBI) in breast cancer patients at low risk of local recurrence. MATERIALS AND METHODS: We compared 490 women randomized to the APBI (ten fractions delivered twice daily over one week) with 488 women in the WBI arm (one fraction per day delivered five days per week over three or six weeks). We took the perspective of the French national health insurance with a three-year time horizon. The outcome was quality-adjusted life years (QALYs). The incremental cost-effectiveness ratio was estimated and uncertainty was explored by probabilistic bootstrapping. Transportation and sick leave costs were added in a sensitivity analysis and a national budget impact analysis based on the incidence of breast cancer estimates in France performed. RESULTS: At three years, the average cost per patient was €2,549 (±1,954) in the APBI arm and €4,468 (±1,586) in the WBI arm (p-value < 0.001), radiotherapy was the main driver of the difference between the two arms. No significant difference was found in QALYs. For an average of 60,000 new cases of breast cancer diagnosed annually in France, 28,000 would be eligible for treatment with APBI. A 100% uptake of APBI would result in a yearly30 million€ cost saving. CONCLUSION: APBI for the treatment of postmenopausal women with early-stage breast cancer is cost saving, with no difference in outcome measured by QALYs.

Stereotactic Body Radiation Therapy for the Management of Hepatocellular Carcinoma: Efficacy and Safety.

This study aimed to describe patient characteristics, treatment efficacy, and safety in patients with hepatocellular carcinoma (HCC) undergoing stereotactic body radiation therapy (SBRT). We retrospectively analyzed data of 318 patients with 375 HCC treated between June 2007 and December 2018. Efficacy (overall survival [OS], relapse-free survival, and local control) and acute and late toxicities were described. The median follow-up period was 70.2 months. Most patients were treated with 45 Gy in three fractions. The median (range) PTV volume was 90.7 (2.6-1067.6) cc. The local control rate at 24 and 60 months was 94% (91-97%) and 94% (91-97%), respectively. Relapse-free survival at 12, 24, and 60 months was 62% (55-67%), 29% (23-36%), and 13% (8-19%), respectively. OS at 12, 24, and 60 months was 72% (95%CI 67-77%), 44% (38-50%), and 11% (7-15%), respectively. Approximately 51% and 38% experienced acute and late toxicity, respectively. Child-Pugh score B-C, high BCLC score, portal thrombosis, high GTV volume, and higher PTV volume reported on total hepatic volume ratio were significantly associated with OS. SBRT is efficient for the management of HCC with a favorable toxicity profile. The outcome is highly related to the natural evolution of the underlying cirrhosis.

Stereotactic Radioablation for Ventricular Tachycardia in the Setting of Electrical Storm.

BACKGROUND: Stereotactic body radiotherapy (SBRT) has been reported as a safe and efficient therapy for treating refractory ventricular tachycardia (VT) despite optimal medical treatment and catheter ablation. However, data on the use of SBRT in patients with electrical storm (ES) is lacking. The aim of this study was to assess the clinical outcomes associated with SBRT in the context of ES. METHODS: This retrospective study included patients who underwent SBRT in the context of ES from March 2020 to March 2021 in one tertiary center (CHU Lille). The target volume was delineated according to a predefined workflow. The efficacy was assessed with the following end points: sustained VT recurrence, VT reduced with antitachycardia pacing, and implantable cardioverter defibrillator shock. RESULTS: Seventeen patients underwent SBRT to treat refractory VT in the context of ES (mean 67±12.8 age, 59% presenting ischemic heart disease, mean left ventricular ejection fraction: 33.7± 9.7%). Five patients presented with ES related to incessant VT. Among these 5 patients, the time to effectiveness ranged from 1 to 7 weeks after SBRT. In the 12 remaining patients, VT recurrences occurred in 7 patients during the first 6 weeks following SBRT. After a median 12.5 (10.5-17.8) months follow-up, a significant reduction of the VT burden was observed beyond 6 weeks (-91% [95% CI, 78-103]), P<0.0001). The incidence of implantable cardioverter defibrillator shock and antitachycardia pacing was 36% at 1 year. CONCLUSIONS: SBRT is associated with a significant reduction of the VT burden in the event of an ES; however, prospective randomized control trials are needed. In patients without incessant VT, recurrences are observed in half of patients during the first 6 weeks. VT tolerance and implantable cardioverter defibrillator programming adjustments should be integrated as part of an action plan defined before SBRT for each patient.

Technical note: Unexpected external markers artifact in 3D k-space based parallel imaging turbo spin-echo magnetic resonance imaging.

PURPOSE: MRI for radiotherapy planning requires spatial referencing using immobilization devices and markers. Clinical images of a difficult-to-interpret artifact are presented, resembling a metastasis, which occurs when combining CAIPIRINHA k-space-based parallel imaging (PI), 3D distortion correction, and external markers. METHODS: A 3D variable flip angle Turbo Spin Echo sequence was used on a 1.5 T and 3 T MRI using flexible and head and neck coils. Two types of markers were tested: Liquimark LM1 and Spee-D-Mark. A silicone oil phantom was used that represents low signal intensity, such as gray matter. 3D Fourier transforms were also used to show the issue's origin. RESULTS: The markers can appear in an unexpected region of a patient, not in the same original or reconstructed slice nor in a rectilinear direction in a slice, especially when using CAIPIRINHA acceleration with 3D distortion correction. The probability of occurrence was respectively 13% and 80% for distances of <=2 mm and >2 mm between marker and patient, for example when using thermoplastic masks. Clinical cases are shown where this semi-randomly occurring artifact appears post contrast only, and thus can be interpreted as metastases. The artifact did not appear when using compressed sensing acceleration. CONCLUSION: Markers used for radiotherapy MRI application can introduce additional artifacts that can be interpreted as metastases. However, other high signal intensity structures on the surface of a patient, such as the ear, can lead to an equivalent error.