Preplanned Technique Research Articles

PO42 Presentation Time: 4:45 PM: Gynecological Brachytherapy Pre-Planning Techniques: An Accurate Tool for Pre-Treatment Applicator Selection and Dose Prediction

<h3>Purpose</h3> To (1) develop a pre-planning technique to inform applicator (app) selection for brachytherapy (BT) treatments and (2) determine if this technique can accurately predict achievable HR-CTV and OAR dose metrics for an Advanced Gynecological Applicator (AGA) with needles. The accuracy of pre-plans generated on routine diagnostic scans and scans with an app present at the time of scan acquisition were evaluated and compared. <h3>Materials and Methods</h3> A retrospective study was performed on a patient who received treatment for Stage IVA cervical cancer. The treatment regimen included EBRT followed by 2 fractions (fxns) of pulsed-dose rate (PDR) BT. Four scans were acquired at different time points for BT planning: (Scan 1) a pre-BT MRI without app prior to PDR fxn 1; (Scan 2) CT with the AGA present at fxn 1; (Scan 3) post-BT1 / pre-BT2 MRI without app and acquired between fxns 1 and 2; and (Scan 4) CT with tandem and ovoids (TO). Solid applicator models (SAMs) of the AGA were rigidly registered (RR) in each of the four scans by a medical physicist. RR prioritized alignment of the SAMs with the HR-CTV and uterus, when possible. For the AGA, the paths of the straight needles were projected to cover the superior extent of the HR-CTV. Five plans were compared. Three plans were retrospectively generated pre-plans (Pre-Plan) using the AGA SAM, one plan was generated at the time of clinical treatment without a SAM (Clin-Plan), and one was a retrospectively re-optimized version of the clinical plan (Re-opt Plan) created using SAMs. Plans generated on Scans 1 and 3 were used to evaluate the accuracy of pre-planning with a SAM registered on a scan without an applicator present. The plan generated on Scan 4 was used to evaluate the accuracy of pre-planning with a SAM different than the app present in the scan. The plan generated on Scan 2 was used for clinical treatment and the dose metrics from the Re-Opt Plan generated on Scan 2 were used as a baseline for comparison with the Pre-Plans and the Clin Plan. All plans were optimized using uniform loading patterns. Contours were drawn by an attending radiation oncologist and plans were generated by a certified medical dosimetrist. An EBRT dose of 45 Gy to the target and OARs was assumed. The EBRT dose was subtracted from the total dose allowed by EMBRACE for each structure, and the remaining dose divided equally between the two PDR fxns. The Pre- and Re-Opt Plans were optimized to escalate dose to the HR-CTV while not exceeding any of the OAR objectives. The dose metrics of each Pre-Plan and Clin-Plan were compared with those of the Re-opt Plans. A clinically acceptable estimate was defined as +/- 6% of total OAR dose. <h3>Results</h3> All pre-plans accurately predicted the HR-CTV D90 to within 5% (Figure 1) regardless of app presence or absence during imaging. Pre-Plans generated with AGA SAMs registered on diagnostic scans without an app present did not accurately predict dose to the OARs (+/- 45% for bladder, +/- 16% for sigmoid). AGA Pre-Plans generated using scans with another app present (TO) accurately predicted the HR-CTV D90 within 5% and the bladder and sigmoid D2cc within 6% and 4%, respectively. The rectum D2cc was not accurately predicted by any of the Pre-Plans, likely due to physical deformations from the BT app placement. <h3>Conclusions</h3> The presence of an app in the scan, even if different from the SAM of interest, estimates the patient's anatomy at the time of implant and permits accurate prediction of dose to the bladder and sigmoid. MRI scans without a tandem in place are not of utility for pre-planning, regardless of timing. The developed pre-planning technique can be used to inform app choice using either pre-Brachy scans or scans acquired during a previous BT treatment fxn.

A worthy technique for transcanal drilling during endoscopic ear surgery

ObjectiveTo evaluate the necessity and effectiveness of a preplanned technique for drilling during transcanal endoscopic ear surgery.MethodsStudy design: Retrospective case series study from June 2011 to June 2015. Setting: Private tertiary care hospital. Patients: Eighty-five ears of 78 patients, age ranging from 9 to 57 years underwent transcanal endoscopic drilling for various types of pathology in their middle and external ear. Interventions: Application of a preplanned technique for transcanal drilling in endoscopic ear surgery that involved short timed drilling with use of intermittent irrigation and suction. Every events of the procedure were done one after another with the single hand of the surgeon. An attachment providing protecting sheath around rotating burr was used during each time of drilling. Main outcomes measure: Efficacy of such drilling technique in single handed endoscopic ear surgery. Presence of any postoperative thermal injury of facial nerve and any lacerated injury of skin of external ear.ResultsThis preplanned technique was found suitable for transcanal endoscopic drilling with the single hand of the surgeon. Postoperative facial nerve palsy or laceration of skin of external ear was not noted in any patient.ConclusionAfter using the present technique, transcanal endoscopic drilling could be done easily and safely with single hand of the surgeon.

A Novel Pre-plan Technique for On-table Adaptation of Pancreatic Stereotactic MR-guided Online Adaptive Radiotherapy

Currently on-table adaptive radiotherapy (ART) is performed by daily re-optimization of initial planning objectives developed from the initial simulation anatomy. Eliminating the initial plan creation may reduce start time, simulation and planning resources, and improve clinical efficacy. We hypothesize that for the treatment of pancreas SBRT using ART, adapting a generic pre-plan to the anatomy of the day results in dosimetrically equivalent plan quality of adapting a patient-specific initial plan to the anatomy of the day. Thirty-eight (n = 38) patients were treated for pancreatic cancer with MR-guided online adaptive radiotherapy (MRgoART) to 50 Gy/5 fractions (fx). An initial plan was developed over 8 days. For on-table adaptation, the initial plan was adapted to the anatomy of the day for each fx and delivered. Retrospectively, we developed a single template pre-plan technique based on optimization objectives from simulation anatomy across 38 patients. To assess feasibility of the pre-plan technique, we adapted the template pre-plan to the on-table fx 3 anatomy of the day (ADAPTtemplate-to-fx3) and compared the plan quality to the patient-specific initial plan adapted to fx 3 anatomy of the day (ADAPTsim-to-fx3) for all patients. Adapted plans were single-optimized and then normalized to greatest violated OAR. RTOG plan quality metrics were evaluated for target coverage (TC) (PTV V100%/PTV vol), homogeneity index (HI) (PTV D2%/ D98%), high dose conformity (PITV), low dose conformity (D2cm), and gradient (R50%). PTV coverage of V100%, D80% were evaluated. Seventy-six (n = 76) adaptions were performed for ADAPTtemplate-to-fx3 and ADAPTsim-to-fx3. Due to plan-normalization, no OARs were violated. PTV coverage was improved for respective ADAPTtemplate-to-fx3 compared to ADAPTsim-to-fx3 for 58% of cases for D80% (45.8±5.9 vs 45.3±9.1, p = 0.8), 61% of cases for TC (0.66±0.30 vs 0.55±0.30, p = 0.1), and 66% of cases for V100% (63±27% vs 55±32% p = 0.2). Homogeneity and conformity indices between respective ADAPTtemplate-to-fx3 and ADAPTsim-to-fx3 were 0.72±0.39 vs 0.60±0.41, p = 0.2 (PITV), 1.94±0.71 vs 1.52±0.22, p<0.001 (HI), 3.14±1.45 vs 3.52±1.80, p = 0.3 (R50%), and 0.61±0.12 vs 0.58±0.22, p = 0.5 (D2cm). For online adaptation in pancreas SBRT, 66% of the single-optimized template plan had improved coverage (PTV V100) with no OAR violation compared to the patient-specific single-optimized initial plan to the anatomy of the day. Given that the plan quality was not significantly different, this works supports AI-plan automation for patients receiving online ART, potentially eliminating the need for initial plan creation and even simulation. Future investigation of the feasibility and efficacy will be launched in a Phase I/II randomized clinical trial between template plan and initial plan for MRgoART.

Maximising forward somersault rotation in springboard diving

Performance in the flight phase of springboard diving is limited by the amounts of linear and angular momentum generated during the takeoff phase. A planar 8-segment torque-driven simulation model combined with a springboard model was used to investigate optimum takeoff technique for maximising rotation in forward dives from the one metre springboard. Optimisations were run by varying the torque activation parameters to maximise forward rotation potential (angular momentum × flight time) while allowing for movement constraints, anatomical constraints, and execution variability. With a constraint to ensure realistic board clearance and anatomical constraints to prevent joint hyperextension, the optimised simulation produced 24% more rotation potential than a simulation matching a 2½ somersault piked dive. When 2 ms perturbations to the torque onset timings were included for the ankle, knee and hip torques within the optimisation process, the model was only able to produce 87% of the rotation potential achieved in the matching simulation. This implies that a pre-planned technique cannot produce a sufficiently good takeoff and that adjustments must be made during takeoff. When the initial onset timings of the torque generators were unperturbed and 10 ms perturbations were introduced into the torque onset timings in the board recoil phase, the optimisation produced 8% more rotation potential than the matching simulation. The optimised simulation had more hip flexion and less shoulder extension at takeoff than the matching simulation. This study illustrates the difficulty of including movement variability within performance optimisation when the movement duration is sufficiently long to allow feedback corrections.

Comparison of two iodine-125 brachytherapy implant techniques for the treatment of lung tumor: Preplanning and intraoperative planning

PurposeTo compare preplanning and intraoperative planning methods of lung tumor brachytherapy based on postimplant CT images and dosimetric outcomes. Methods and MaterialsDetailed postimplant evaluations of iodine-125 seed implants were performed in 15 patients using a preplanning technique and in 15 patients treated with an intraoperative planning technique. The implant details, dosimetric parameters, and implant quality indices were compared. Furthermore, the dose to the lung and the incidence of complications were compared. ResultsThe planning target volume was similar in both groups (p = 0.496). The median V100%, V150%, and V200% values (the percent of the planning target volume receiving 100%, 150%, and 200% of the prescription dose) for the intraoperative planning technique were 95.65%, 76.47%, and 59.80%, respectively. The median V100%, V150%, and V200% values for the preplanning methodology were 88.86%, 69.23%, and 28.30%, respectively (p < 0.01). The median values of the coverage index, c1, conformity index, and plan quality index were higher in the intraoperative planning group than in the preplanning group (p < 0.05). The overdose volume index and dose nonhomogeneity ratio were higher in the intraoperative group (p < 0.05), and the dose homogeneity index was lower in the intraoperative group (p < 0.05) than in the preplanning group. No significant differences were observed in the reference dose (VREF), external index, or lung doses between the two groups. The incidences of pneumothorax and hemoptysis were minimal in both groups. ConclusionThese data showed that the intraoperative planning method was superior to the preplanning method for the treatment of lung tumors.

Multicenter Evaluation of Biochemical Relapse–Free Survival Outcomes for Intraoperatively Planned Prostate Brachytherapy Using an Automated Delivery System

To report biochemical recurrence in prostate cancer treated with intraoperatively planned low-dose-rate prostate brachytherapy using an automated delivery system (IO-LDRB). Between 2003 and 2013, 2608 patients from 3 centers were treated with IO-LDRB as single-modality treatment for low or low-tier intermediate-risk prostate cancer. Databases from the 3 centers have been analyzed. These independent databases were collected prospectively. Patient, tumor, and treatment characteristics were then compared, Kaplan-Meier survival estimates of biochemical relapse-free survival (bRFS) were generated, and the Cox proportional hazards model was used to determine factors predicting for relapse. A total of 2608 patients with a median follow-up of 4.7 (interquartile range, 3.1-6.9) years were analyzed. Median age was 64 (range, 42-84) years. In these patients, median initial prostate-specific antigen was 5.5ng/mL, 74% were T1, and 26% were T2; 73% were Gleason 6, and 25% Gleason 7. Median percentage of biopsy cores positive was 33%, and median gland volume was 34.2 cm3. Eleven percent of patients received hormones for a median of 3.0months before implantation. Median seed activity was 0.437mCi, D90 (dose covering 90% of the prostate volume) was 186.7Gy, and V100 was 99.37%. Biochemical relapse was observed in 124 patients (4.8%), and median time to failure was 4.0years. Predicted bRFS was 93% at 7years. On Cox regression bRFS was dependent only on D90 at the time of implantation and prostate-specific antigen density. This study demonstrates that IO-LDRB is an effective treatment option for patients with low and low-tier intermediate-risk prostate cancer. Rates of biochemical relapse remain low several years after treatment. These results compared favorably to published manual preplan technique results.

Implementation and Advantages of a Pre-Planning Technique for Interstitial Gynecological Brachytherapy

Implementation and Advantages of a Pre-Planning Technique for Interstitial Gynecological Brachytherapy

Pre-plan technique feasibility in multi-interstitial/endocavitary perineal gynecological brachytherapy.

PurposeTo present the implementation of a magnetic resonance imaging (MRI) pre-planning technique in multi-interstitial perineal and endocavitary gynecological brachytherapy.Material and methodsWe used a new fully MRI-compatible applicator that is capable to engage titanium needles, and an intrauterine tandem, developed in our department for the treatment of gynecological cervical cancer patients. This applicator is an attempt to combine the technical advantages of the Martinez universal perineal interstitial template (MUPIT) with the improvement in dose distribution by adding an intrauterine probe with the imaging advantages of MRI-based brachytherapy, thus preserving the stability, geometry, and robustness of the implant, avoiding possible errors of free-hand needle placement. A pre-brachytherapy MRI T2 acquisition is carried out with the template in place 3-5 days before the implant. On this image set, clinical target volume (CTV) is drawn. The required needles and their depths are selected accordingly to encompass the CTV (as conformal as possible). To facilitate this task, a Java based application linked to the treatment planning system has been developed. From this procedure, each needle identification and its depth are obtained previously to the implantation. With this information, the radiation oncologist proceeds with implant and then, a post-implant MRI is carried out, in which the contouring, needles, tandem reconstruction, and optimization are established.ResultsThis pre-planning procedure has been successfully applied in 10 patients. An excellent reproduction of the virtual pre-planning has been achieved.ConclusionsWe describe a virtual pre-planning technique using a multi-interstitial and endocavitary perineal template. It is based on a virtual work with MRI images. This procedure has shown to be feasible and efficient in clinical practice by facilitating the work of specialists, and reducing uncertainties of the application.

Introduction of novel 3D-printed superficial applicators for high-dose-rate skin brachytherapy

PurposeCustom-made surface mold applicators often allow more flexibility when carrying out skin brachytherapy, particularly for small treatment areas with high surface obliquity. They can, however, be difficult to manufacture, particularly if there is a lack of experience in superficial high-dose-rate brachytherapy techniques or with limited resources. Methods and MaterialsWe present a novel method of manufacturing superficial brachytherapy applicators utilizing three-dimensional (3D)–printing techniques. We describe the treatment planning process and the process of applicator manufacture. ResultsThe treatment planning process, with the introduction of a pre-plan, allows for an “ideal” catheter arrangement within an applicator to be determined, exploiting varying catheter orientations, heights, and curvatures if required. The pre-plan arrangement is then 3D printed to the exact specifications of the pre-plan applicator design. This results in improved target volume coverage and improved sparing of organs at risk. ConclusionsUsing a pre-plan technique for ideal catheter placement followed by automated 3D-printed applicator manufacture has greatly improved the entire process of superficial high-dose-rate brachytherapy treatment. We are able to design and manufacture flexible, well-fitting, superior quality applicators resulting in a more efficient and improved patient pathway and patient experience.

Obstacle Avoidance Approaches for Autonomous Underwater Vehicle: Simulation and Experimental Results

Autonomous underwater vehicles (AUVs) operate in unknown underwater environments and must be able to avoid submerged obstacles such as cliffs, wrecks, and seabed changes. This paper proposes a methodology for obstacle avoidance by AUVs that are equipped with forward-looking sonars (FLSs). The data collected from two FLSs placed in horizontal and vertical orientation are processed in real time to provide obstacle detection information in the $xz$ - and $xy$ -planes, respectively. Due to the necessity of maintaining constant height when employing sidescan sonar (SSS) and lower energy consumption, horizontal avoidance maneuvers are preferred over vertical ones. For the horizontal obstacle avoidance, a two-layer obstacle avoidance algorithm (OAA) contains two different processes, an OAA based on Bandler and Kohout (BK) product of fuzzy relation used as a preplanning method and a reactive approach based on potential field and edge detection methods. The preplanning technique has a clear advantage on a line segment of the path, and the reactive method is more efficient on a curved segment. In case a horizontal approach cannot find a path to safely avoid the obstacle, the reactive vertical approach is activated. A seabed gradient detection technique that allows prediction of seabed and altitude changes up to 40 m ahead of the AUV is presented. Simulation and experimental results clearly demonstrate that the proposed methodology enables AUVs to navigate safely through obstacles and provide crucial information about the seafloor terrain changes.

A preplanning method for stereotactic radiosurgery to improve treatment workflow.

Frame‐based stereotactic radiosurgery (SRS) requires fixation of an invasive head ring to ensure accurate targeting. Minimizing waiting time with a fixed head ring is important for patient comfort and satisfaction. We report a practical preplanning solution for the Brainlab iPlan treatment planning system that reduces waiting time by expediting the planning process on treatment day. A water‐filled anthropomorphic head phantom was used to acquire a surrogate CT image set for preplanning and fused with patient's MRI, which was obtained before the day of treatment. Once an acceptable preplan was obtained, it was saved as a plan template and the phantom image set was removed from the Brainlab database to prevent any confusion and mix‐up of image sets. On the treatment day, the patient's CT and MRI were fused, and the customized beam settings of the preplan template were then applied and optimized. Up to 10‐fold of reduction in treatment plan time was demonstrated by bench testing with multiple planners and a variety of cases. Loading the plan template and fine‐tuning the preconfigured beam settings took only a small fraction of the preplan time to restore the conformity and dose falloff comparable to those of the preplan. For instance, preplan time was 2 hr for a two‐isocenter case, whereas, it took less than 20 min for a less experienced planner to plan it on the day of treatment using the preplan method. The SRS preplanning technique implemented in this study for the Brainlab iPlan treatment planning system offers an opportunity to explore possible beam configurations thoroughly, optimize planning parameters, resolve gantry angle clearance issues, and communicate and address challenges with physicians before the treatment day. Preplanning has been proven to improve plan quality and to improve efficiency in our clinic, especially for multiple‐isocenter and dosimetrically challenging cases.PACS number(s): 87.53.Ly, 87.55.D‐, 87.55.Gh, 87.55.tm

Pre-Plan Technique Feasibility in Multi-Interstitial Gynecological Brachytherapy

Pre-Plan Technique Feasibility in Multi-Interstitial Gynecological Brachytherapy

Brachytherapy: state‐of‐the‐art radiotherapy in prostate cancer

Brachytherapy: state‐of‐the‐art radiotherapy in prostate cancer

Comparison of three different techniques of low-dose-rate seed implantation for prostate cancer.

PurposeThree different techniques of low-dose-rate seed implantation for prostate cancer have been used since its use started in our hospital. The purpose of this study was to compare the results of the three different techniques.Material and methodsThe data of 305 prostate cancer patients who underwent low-dose-rate seed implantation were retrospectively analyzed. Pre-plan technique (n = 27), intraoperative pre-plan technique (n = 86), and interactive plan technique (n = 192) were tried in chronological order. The prescribed dose was set at 145 Gy.ResultsMedian follow-up was 66 months (range: 12-94 months). The 5-year biochemical control rate was 95.5% (pre-plan group: 100%, intraoperative pre-plan group: 90.7%, interactive plan group: 97.0%; p = 0.08). Dosimetric parameters were generally increased from the pre-plan group to the interactive group. The differences in some dosimetric parameters between the planning phase and the CT analysis were significantly reduced with the interactive plan compared to the other techniques. The interactive plan showed a significant reduction of the seed migration rate compared to the two other groups. Acute genitourinary toxicity, acute gastrointestinal toxicity, frequency, and urinary retention increased gradually from the pre-plan period to the interactive plan period.ConclusionsThere was no significant difference in biochemical control among the three groups. Dose-volume parameters were increased from the pre-plan technique to the interactive plan technique. However, this may not necessarily be due to technical improvements, since dose escalation was started during the same period. Lower seed migration rates and the smaller differences between the planning phase and CT analysis with the interactive plan technique suggest the superiority of this technique to the two other techniques.

Preliminary Results of a Pilot Study of Focal Salvage High-Dose-Rate Prostate Brachytherapy in Patients with Local Recurrence after Definitive External Beam Radiotherapy

Purpose: Permanent prostate implants (PPI) are performed since 1994 in our institution. The analysis of 1794 patients treated between 1994 and 2012 was done to evaluate the seed loss and migration rate over this period. The impact of implantation techniques on seed migration, such as the introduction of intraoperative technology, was evaluated. The correlation between seed loss/migration and the experience of the physician performing the implant was also explored. Materials and Methods: Post-implant evaluations were done 30 days after the implant for all patients. Migration was defined as one or more seed found outside the prostate region and confirmed by imaging (CT or kV). Most of the time, the migrated seeds were located in the lungs while uncommon locations included kidneys, heart and sacrum. Seed loss was defined as at least one seed missing at the post-implant evaluation, excluding the migrated seeds found in the patient. Seeds might be lost through micturition but miscount on kV images remains a possibility. Since January 2004, all PPI patients were surveyed using a collimated NaI gamma scintillator to detect seed migration to the chest. Before this date, the total number of migrated and lost seeds is reported without differentiation. The seed loss and migration rate are reported for three different implantation techniques: manual, guidance and robotic. The manual group (G1) consists of implants performed with a pre-planning technique and 2D TRUS insertion. The guidance group (G2) were done using OR planning and 3D TRUS insertion with guidance (SPOTPRO, Nucletron). The robotic group (G3) were implanted with the FIRST system (Nucletron) similar to the second group G2 but with robotic needle extraction. Groups were compared using Pearson khi-2 test. Results: The proportions of patients with seed migration were 17%, 15.5% and 8% for the G1, G2 and G3 groups respectively. The difference between G1-G3 or G2-G3 are statistically significant (p5 0.0028 and 0.002). For patients with either migration or loss, rates were 39%, 26% and 23.6% for the G1, G2 and G3 groups, respectively. There is a significant difference between G1-G3 (p 5 0.0005). The introduction of intra-op planning between 2003 and 2004 had a significant impact on both migration and seed loss rates (p50.0049). The rate of seed migration/loss tended to decrease as physicians gained experience in the implantation technique. Conclusions: Seed migration and loss rates are related to the implantation technique, with the robotic-assisted technique leading to the best results. Data also suggest that the experience of the physician performing the implant has an impact on migration/loss rates. PD56

The dosimetric impact of supplementing pre-planned prostate implants with discretionary 125I seeds

AbstractIntroductionProstate implants at the British Columbia Cancer Agency are performed using a pre-planned technique. Physicians can augment the dose distribution using one to five non-planned ‘extra’ seeds and this option is determined without intraoperative feedback. The purpose of this research is to quantify the dosimetric impact of extra seeds and to assess the circumstances under which they are considered necessary.Materials and methodsImplanting physicians used a questionnaire to record the three-dimensional location and their rationale for using extra seeds. A plan reconstruction algorithm was used to distinguish the extra seeds from the planned seeds. Distributions with and without extra seeds were calculated to quantify the dosimetric impact to the prostate, urethra and rectum.ResultsExtra seeds resulted in mean relative increases to V100, V150 and V200 of 3·7%, 13% and 19·1%, respectively. Mean prostate D90 increased from 147 to 156 Gy. Improvements in post-implant quality assurance codes were recorded in 30% of the implants with minimal dose increase to the rectum and urethra. Extra seeds were mainly deposited in the prostate anterior–superior quadrant.ConclusionsThe use of two to five extra seeds can result in improvements to pre-planned prostate implants, whereas the costs in terms of increased rectal and prostatic urethral dose are relatively minor.

SU‐E‐T‐473: Preplanning of Stereotactic Radiosurgery Using the Brainlab IPlan Treatment Planning System

Purpose: Frame‐based stereotactic radiosurgery (SRS) requires fixation of an invasive head ring to ensure accurate targeting. Minimizing waiting time with head ring on is important for patient comfort and satisfaction. We report a practical preplanning solution for the Brainlab iPlan treatment planning system (TPS) that reduces waiting time by expediting the planning process on treatment day. Methods: A water‐filled anthropomorphic head phantom was used to acquire a surrogate CT image set for preplanning and fused with patient MRI image set which is usually available before the treatment day. Once an acceptable preplan was obtained, it was saved as a plan template and the phantom image set was removed from the Brainlab database to prevent any confusion and mix‐up. On treatment day, patient CT was fused with MRI, customized beam settings from the preplan template were applied and optimized. Considerable reduction in treatment planning time was demonstrated by bench testing with both a conformal beam and a circular arc case. Results: Preplans were generated in 20–25 minutes to satisfy &lt;130% homogeneity, 100% coverage and &lt;2.0 conformity index with the phantom CT. After applying the plan template and fine‐tuning the pre‐configured beam settings, treatment plans of comparable evaluation indices were obtained in 5 min and 1 min for the conformal and arc cases, respectively. This technique was successfully applied to our last 16 patient treatments. Conclusion: The SRS preplanning technique implemented in this study for the Brainlab iPlan TPS offers an opportunity to thoroughly explore possible beam configurations, optimize planning parameters, resolve gantry angle clearance issues, and communicate and address challenges with physicians before treatment day. Preplanning has proven useful and time‐saving in our clinic particularly for multiple‐isocenter and dosimetrically challenging cases.

Comparison of Preplanning and Intraoperative Planning for I-125 Prostate Brachytherapy

To compare two widely used permanent prostate brachytherapy techniques, preplanning and intraoperative planning, based on postimplant dosimetry, toxicity and biochemical outcomes. Between 2003 and 2006, 665 men with localized prostate cancer were treated with permanent interstitial implantation. The first 227 consecutive men were treated with the preplanning technique, followed by 438 men treated with the intraoperative technique. Late toxicity was scored by the Common Terminology Criteria for Adverse Events v.4.0. Biochemical failure was defined as a prostate-specific antigen increase of more than 2 ng/ml above the nadir value excluding a benign bounce. Univariate and multivariate analyses were performed to identify the variables associated with biochemical failure-free survival. Postimplant target coverage was similar in the two groups, with a small difference in risk organ doses. Mean V100 was 96.3 vs. 96.7% (P = 0.205), D90 was 119.6 vs. 119.4% (P = 0.884), urethral D10 was 157.5 vs. 146.1% (P = 0.010), rectal V100 was 0.57 vs. 0.43 cc (P = 0.002) in the preplanning and intraoperative planning groups, respectively. Acute and late Grade 3 genitourinary and gastrointestinal toxicities were <1% for both methods. The 5-year biochemical failure-free survival rate was 95.4% for the preplanning and 94.0% for the intraoperative planning group (P = 0.776). Multivariate analysis revealed Gleason score, biopsy positive rate and V100 to be predictors of biochemical failure-free survival, while the planning technique was not significant. This large-scale analysis of high-quality implants revealed similar postimplant dosimetry, toxicity profiles and biochemical failure-free survival for the preplanning and intraoperative planning methods.

Progressive transition from pre-planned to intraoperative optimizing seed implant: post implementation analysis

PurposeTo perform a dosimetric comparison between a pre-planned technique and a pre-plan based intraoperative technique in prostate cancer patients treated with I-125 permanent seed implantation.Material and methodsThirty patients were treated with I-125 permanent seed implantation using TRUS guidance. The first 15 of these patients (Arm A) were treated with a pre-planned technique using ultrasound images acquired prior to seed implantation. To evaluate the reproducibility of the prostate volume, ultrasound images were also acquired during the procedure in the operating room (OR). A surface registration was applied to determine the 6D offset between different image sets in arm A. The remaining 15 patients (Arm B) were planned by putting the pre-plan on the intraoperative ultrasound image and then re-optimizing the seed locations with minimal changes to the pre-plan needle locations. Post implant dosimetric analyses included comparisons of V100(prostate), D90(prostate) and V100(rectum).ResultsIn Arm A, the 6D offsets between the two image sets were θx=−1.4±4.3; θy=−1.7±2.6; θz=−0.5±2.6; X=0.5±1.8 mm; Y=−1.3±−3.5 mm; Z=−1.6±2.2 mm. These differences alone degraded V100 by 6.4% and D90 by 9.3% in the pre-plan, respectively. Comparing Arm A with Arm B, the pre-plan based intraoperative optimization of seed locations used in the plans for patients in Arm B improved the V100 and D90 in their post-implant studies by 4.0% and 5.7%, respectively. This was achieved without significantly increasing the rectal dose (V100(rectum)).ConclusionsWe have progressively moved prostate seed implantation from a pre-planned technique to a pre-plan based intraoperative technique. In addition to reserving the advantage of cost-effective seed ordering and efficient OR implantation, our intraoperative technique demonstrates increased accuracy and precision compared to the pre-planned technique.

Preliminary Result of Permanent Prostate Brachythrerapy Using Hybrid Interactive Mick Technique

Purpose: The aim of this study was to show that Hybrid interactive technique brought good dosimetric outcome and acceptable treatment time and morbidity for a new brachytherapy team. Materials and Methods: Between April 2005 and April 2010, 289 consecutive patients were underwent permanent prostate brachytherapy in our institution. Of the 289 men, we assessed the 256 patients who were not treated with additional external beam radiation therapy with the aim of the simplification of this study. Using D’Amico classification, 132 (51%) were low risk, 124 (49%) were intermediate risk patients. Before the introduction of hybrid interactive technique, only three patients were treated with preplan technique. Of the 256 patients, first 22 patients were treated intraoperative preplan (i-Hybrid) (with interactive seed delivery modification 5 broad sense of hybrid interactive technique) and after all 234 patients were treated with our Hybrid interactive Mick technique. Prostate plus 3mm margin was determined CTV. In the preplan volume study and intraoperative volume study, prescription dose for CTV is 145Gy. We evaluated the procedure time, post plan dosimetry and morbidity. For postplan dosimetry we use CT image performed post Day 30. We use CTCAE ver.4 for evaluation of morbidity. Results: Median procedure time of 256 patients with Hybrid interactive technique 55 minutes. Hybrid interactive technique making 3 or 4 plans, preplan volume study, intraoperative preplan volume study, interactive plan with inserted needles (IP_1), and interactive modification using feedback of dropped seeds of real time dosimetry (IP_2) I-Hybrid use preplan volume study, intraoperative preplan volume study, and our Hybrid interactive technique use all 4 plans. In spite of such many times of planning, we did not need extended procedure time. Day30 CT dosimetric parameters were prostateD90; 168Gy, V100; 97.4% V150; 54.1% Urethral D90; 162Gy. D5; 208Gy. As the median followup of 36 months morbidity, of the 256 no one experienced over Grade 3 acute urinary morbidity with median followup 36 months. Five patients (2%) needed temporally urethral catheterization, grade 2 toxicity. Four patients (one is low risk and three are intermediate risk) were showed PSA failure as the criteria of ASTRO Phoenix consensus definition. One low risk patient continue to rising the number of PSA up to 7, in spite of good dosimetric results, then he was started to treat with hormonal therapy. But no one experienced definite local recurrence or metastasis. Conclusions: It is said state-of-the-art technology enables a new brachytherapy team to obtain excellent post dose distribution. In the same way, hybrid interactive technique enables a new brachytherapy team to shift preplan technique to interactive technique in a short experience and to obtain excellent post dosimetric outcome, procedure time and also achieve acceptable morbidity rate.