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Purpose: Prostate cancer patients who undergo a radical prostatectomy and have high risk features are offered radiation therapy to the surgical bed. Modern planning and delivery techniques (like IMRT) that provide conformal dose coverage and steep dose fall‐offs require daily localization, especially when tight margins are utilized. The goal of this study is to investigate the use of surgical clips in and around the prostate bed as alignment landmarks. Materials and methods: During the simulation process the physicians contoured at least three different groups of clips as reference structures. The reference structures along with the isocenter were then electronically transferred to the alignment computer. CT‐on‐rails was then used for daily imaging and the clips were aligned with the reference structures. Each alignment was documented as a printout showing the pre‐treatment scan, the reference structures, and the anatomical structures in the three main planes. Every printout was evaluated by the treating physician. A total of 45 patients have been treated using this technique. Ten random patient charts (total of 306 alignments) were selected and the number of the satisfactory alignments was counted. Results: The physician approval rate was 100% for each of the ten patients coming from three different physicians. Furthermore, the physicians could not recall a misalignment that would violate the PTV margin used for planning (8 mm) over the total number of 45 patients (between 1300 and 1400 alignments). Conclusions: The presented results suggest that the technique described here results in a very high physician approval rate. The fact that planning and alignments are performed with the same imaging modality leads to a high level of confidence in both therapists and physicians.

Purpose: Radiation target dose, target margin, and the doses to the surrounding normal tissues are traditionally applied in a standard way (e.g., 76–78Gy to patients with intermediate to high risk prostate cancer). The hypothesis here is that quality of life will be improved on an individual basis by allowing these aspects to vary, within limits, based on the preferences of a given patient in terms of local control and normal tissue toxicities. The goal is to develop planning methods for incorporating utilities. Method and Materials: Patient utilities are individual valuations of various health states. Through the incorporation of utilities in the IMRT planning process, the treatment may be tailored to the individual patient desires. The assessment of utilities is ongoing. In this study, DVHs for the target and critical organs are used to estimate tumor control and normal tissue complications and then converted to utility scores. We included utility assessment for baseline general health, and urinary, sexual, and bowel functions. Preliminary results are based on multiple IMRT plans using a commercial TPS. An automated planning process is being developed using a home‐grown optimization system. Results: Outcome data from the literature and our own institution are used to establish a consistent DVH‐utility conversion system. Although such a scoring system is based on the mean values of a patient population the changes in the utility scores for a particular patient are relative and relevant based on the dosimetric changes in the treatment plans. Emphasis is given to dose in the target, rectum, bladder and erectile tissue to maintain the balance between local control, rectal/bladder bleeding, urinary functions and impotence. Patients are given the opportunity to make treatment decisions by selecting personalized utility criteria. Conclusion:Treatment optimization based on utility analysis allows both the oncologist and patient to make personalized treatment decisions.

Purpose: To evaluate the safety and efficacy of MR guided focused ultrasound (MRgFUS) treatment for bone metastases. Methods: Six patients with scapula (2), humeral head, sacrum, ilium and pubic ramus bone metastases were treated using ExAblate 2000 under MR guidance. In addition to the monthly and annual quality assurance (QA), pre‐treatment machine calibration was performed before each treatment including the functionality of the treatmentsoftware and the mechanical motion control systems. The effective ultrasound focal spot was verified with an acoustic phantom using MR thermometry. The patient was positioned on a gel pad. The interface between the treatment table, the gel pad and the patient was immersed in degassed water for acoustic coupling. Caution was taken to remove all gas bubbles between the interfaces.Treatment was performed under conscious sedation. Six to eighteen sonications were delivered for each patient treatment depending on each lesion's size. Patients were treated with a frequency of 1 MHz; 32 ± 4.0 to 96 ±11W acoustic power and 628 ± 78 to1859 ± 338J energy for 20–30s for each sonication. MR phase images were used to monitor the temperature changes in real‐time. Based on the temperature feedback, the acoustic power was adjusted to reach designed temperatures (=60 °C) for individual sonications. Pain was assessed using the visual analog scale (VAS). Results: All patients tolerated the MRgFUS treatment well. No skin toxicity or other complications were observed. The VAS pain rating was significantly reduced for all 6 patients from 8.2 ± 0.8 before treatment to 4.7 ± 3, 2.7 ± 1.5 and 1.8 ± 1.1 at one day, one month and three months respectively. Conclusions: A comprehensive QA program has been developed for the MRgFUS system. Our data suggest that MRgFUS is a safe, effective and noninvasive treatment modality for palliation of bone metastases.

Purpose: To evaluate the safety and efficacy of MR guided focused ultrasound (MRgFUS) treatment for bone metastases. Method and Materials: A 50‐year‐old patient with painful scapula bone metastases refractory to pain medication was recruited in this study. The treatment was performed under local IRB approval using an MRgFUS system consisting of an Insightec ExAblate 2000 with a GE 1.5T MR scanner. The focal region is approximately 2mm in diameter and 10mm in length. Beside the regular monthly and annual quality assurance (QA) measurements, pre‐treatment machine calibration included the functionality of the treatment software and the mechanical motion control. The focal spot was verified using MR thermometry. The safety system and panic buttons were checked. The patient is positioned on a gel pad on the treatment table in line with the transducer. The gel pad was immersed in degassed water that acts as an interface between the treatment table and the gel pad for acoustic coupling. Caution was taken with all gas bubbles removed between the interfaces. Treatment was performed under conscious sedation. Six sonications were delivered with frequency 1 MHz, acoustic power 32 ±4 W, energy 628±78 J and 20s durations. Phase MR Images were used to monitor the temperature change in real‐time. Based on the treatment feed back, acoustic power was adjusted to reach designed temperatures (⩾60 °C) for individual sonications. Results: The patient tolerated the MRgFUS treatment well. There were no treatment‐related adverse events including skin toxicity. The patient reported rapid pain decrease from 8 out of 10 (0 –10 scale) pretreatment to 2 within 24 hrs, and has continued to report between 2 – 2.5 up to 2 months following treatment. Conclusions: MRgFUS is a safe, effective and noninvasive treatment modality for bone palliation and pain relief. A comprehensive QA program has been developed for the MRgFUS system.

Purpose: The purpose of this work is to develop an effective and efficient quality assurance (QA) program for the application of MR guided focused ultrasound (MRgFUS) as a multi‐modality platform for cancer therapy. Materials and Method: An MRgFUS system has been installed in our institution, which consists of an InSightec ExAblate 2000 high‐intensity focused ultrasound (HIFU) system and a 1.5T GE MR scanner. This system has been FDA approved for the treatment of uterine fibroids clinically and is being investigated under local IRB approval for treating bone metastases, prostate and breast cancers and the enhancement of drug delivery for gene therapy and chemotherapy. In addition to the daily, monthly and annual calibration and commissioning measurements for the MRI unit special QA procedures were developed for the HIFU system including the mechanical motion of the couch and transducer, the safety system and patient panic buttons, the functionality of the temperature mapping and treatment software, the acoustic power output and the localization of the treatment focal spot. Results: The MRgFUS system has been operational since the fall of 2006. Successful experiments have been performed on in vitro bio‐samples and in vivoanimal models for pre‐clinical studies and for drug enhancement experiments. Patients with bone metastases have been treated successfully using the MRgFUS system for pain relief with a pre‐treatment QA procedure. Patients tolerated the HIFU treatment well. No skin damage was observed after treatment. The pain scale was significantly reduced within 24 hours and further reduced at later follow‐ups. Conclusions: Comprehensive QA procedures have been developed for the safe and successful operation of the MRgFUS system as a multi‐modality platform for breast surgery, bone palliation, and prostate boost in combination with radiotherapy clinically and for drug delivery enhancement investigations for gene therapy and chemotherapy using animal models.

Purpose: The purpose of this work was to commission and to evaluate the role of MR guided high intensity focused ultrasound (MRgHIFU) in cancer therapy in ex vivo and in vivo. Method and Materials: An InSightec ExAblate 2000 HIFU system with a 1.5T GE MR scanner (MRgHIFU) is approved by FDA for the treatment of uterus fibroids clinically and being investigated in our department for treating bone metastases, prostate and breast cancers under local IRB approval. The phased arraytransducer is housed in a sealed bath and connected to a motion system. The focal region is cigar shaped, about 2mm in diameter and 10mm in focal length. Extensive experiments have been carried out on phantoms and excised tissues to determine optimal ultrasound parameters including the acoustic power output, frequency and exposure duration. We also performed in vivo studies on feasibility of enhancement of drug delivery for both chemotherapy and gene therapy using an animal model. Both MR T2‐weight MR image and proton resonance frequency shift MR images were used for treatment planning and monitoring the effect of the treatment in real time. Results: Phantom studies demonstrated that MRgHIFU could provide adequate temperature elevation for tissueablation; acoustic power >10W leading to temperature elevation (ΔT) > 7 °C. At a lower acoustic power (5 W) we could keep ΔT < 4 °C, which is adequate for drug enhancement. The results were served for animal studies. Tissue damage was achieved at predetermined region in excised tissue through MR real‐time guidance. Our preliminary results showed increased drug concentrations in MRgHIFU treated mice than the control group. Conclusion: MRgHIFU may have a great potential as a safe, noninvasive treatment modality for cancer therapy including tumorablation, enhancement of drug livery and boost treatment for hypoxic tumors in combination with radiotherapy.

Purpose: Prostate cancer is often treated with intensity‐modulated radiation therapy(IMRT) that provides very steep dose fall‐off outside of the target volume and therefore requires precise alignment. In this report, we compare ultrasound (U/S) and CT localization, and evaluate the uncertainties of the two modalities. Method and Materials: A total of 19 prostate patients (275 alignments) were included in the study. The prostate was localized with the BAT U/S system (Nomos, Cranberry, PA). CT scans were performed with the Primatom CT‐on‐Rails system (Siemens, Concord, CA). The two alignment techniques were identical: the simulation contours of the prostate, proximal seminal vesicles, bladder, and rectum were aligned with a pre‐treatment image. The random uncertainty of the CTsystem was estimated based on intra‐user variability, and a simple mathematical model of the motion of radio‐opaque markers. Then the random error of the ultrasound alone was calculated. Results: The systematic differences between (U/S) and CT alignments were (in mm): 0.3 (lateral), 0.4 (AP) and 0.3 (longitudinal). The random differences between the two modalities (one standard deviation) were (in mm): 2.2 (lateral), 2.2 (AP) and 2.4 (longitudinal). The estimated ranges of random uncertainties of the CT alignments (one standard deviation) were (in mm): 0.9 to 1.2 (lateral), 0.7 to 1 (AP), and 1.2 to 1.5 (longitudinal). Based on these results, the calculated ranges of random uncertainties of the U/S alignments were (in mm): 1.8 to 2.0 (lateral), 2.0 to 2.1 (AP), and 1.9 to 2.1 (longitudinal). Conclusion: There was a strong correlation between the extent of prostate inter‐fraction alignments using ultrasound and CT. The localization of the prostate had a total uncertainty (two standard deviations) of 2 to 3 mm when using the Primatom CT‐on‐Rails and around 4 mm when using the BAT system.

Purposes: The purpose of this work is to retrospectively verify treatmentdose delivered in patients treated with stereotactic radiotherapy (SRT) to the lung.Method and Materials: In this study, a stereotactic body localizer (SBL) system was used for lungcancer patient immobilization in the CT simulation and stereotactic treatment planning on a prospective dose escalation protocol for malignant lungtumors. Prior to each treatment, a localization CT san was obtained in the treatment room after the patient was immobilized in the SBL. The stereotactic coordinates of three pre‐selected bony landmarks were recorded from the pre‐treatment scan and compared with those of the planning scan. Couch shifts were made based on the bony‐landmark displacements. Image fusion was performed between the simulation CT scan to each pre‐treatment CT scan in order to obtain the same planning target volumes (PTVs) and critical structures. The same treatment plans were re‐loaded onto each pre‐treatment CT scan with their respective stereotactic coordinate system. The changes in dose distributions were assessed by dose‐volume histograms of the PTV and normal structures for the old and new isocenter coordinates using the bony‐landmark shifts. We compared D95, D99, and V95 for the PTV and GTV, and V20 and V30 for the ipsilateral lung.Results: Our preliminary study for 6 patients with 20 dose reconstructions showed that the average D95, D99, and V95 of the PTVs are 95.9%, 93.6%, and 98.4% of the planned values before bony‐landmark shifts. With the bony‐landmark shifts, these values are all improved to 100% of the planned values. The average V20 and V30 are 7–8% higher than the planned values without bony‐landmark shifts and recovered the planned values after the corrections. Conclusion: With near real‐time 3D image guidance for setup error correction, the delivered dose distribution can be ensured for SRT hypofractionated lungtreatment.