Automated survey of 8000 plan checks at eight facilities.

PURPOSE: To identify policy and system related weaknesses in treatment planning and plan check work-flows. METHODS: The authors' web deployed plan check automation solution, PlanCheck, which works with all major planning and record and verify systems (demonstrated here for mosaiq only), allows them to compute violation rates for a large number of plan checks across many facilities without requiring the manual data entry involved with incident filings. Workflows and failure modes are heavily influenced by the type of record and verify system used. Rather than tackle multiple record and verify systems at once, the authors restricted the present survey to mosaiq facilities. Violations were investigated by sending inquiries to physicists running the program. RESULTS: Frequent violations included inadequate tracking in the record and verify system of total and prescription doses. Infrequent violations included incorrect setting of patient orientation in the record and verify system. Peaks in the distribution, over facilities, of violation frequencies pointed to suboptimal policies at some of these facilities. Correspondence with physicists often revealed incomplete knowledge of settings at their facility necessary to perform thorough plan checks. CONCLUSIONS: The survey leads to the identification of specific and important policy and system deficiencies that include: suboptimal timing of initial plan checks, lack of communication or agreement on conventions surrounding prescription definitions, and lack of automation in the transfer of some parameters.

Tomotherapy and multifield intensity-modulated radiotherapy planning reduce cardiac doses in left-sided breast cancer patients with unfavorable cardiac anatomy.

PURPOSE: For patients with left-sided breast cancers, radiation treatment to the intact breast results in high doses to significant volumes of the heart, increasing the risk of cardiac morbidity, particularly in women with unfavorable cardiac anatomy. We compare helical tomotherapy (TOMO) and inverse planned intensity modulated radiation therapy (IMRT) with three-dimensional conformal radiotherapy using opposed tangents (3D-CRT) for reductions in cardiac volumes receiving high doses. METHODS AND MATERIALS: Fifteen patients with left-sided breast cancers and unfavorable cardiac anatomy, determined by a maximum heart depth (MHD) of >or=1.0 cm within the tangent fields, were planned for TOMO and IMRT with five to seven beam angles, in addition to 3D-CRT. The volumes of heart and left ventricle receiving >or=35 Gy (V35) were compared for the plans, as were the mean doses to the contralateral breast and the volume receiving >or=20 Gy (V20) for the ipsilateral lung. RESULTS: The mean MHD was 1.7 cm, and a significant correlation was observed between MHD and both heart and left ventricle V35. The V35s for IMRT (0.7%) and TOMO (0.5%) were significantly lower than for 3D-CRT (3.6%). The V20 for IMRT (22%) was significantly higher than for 3D-CRT (15%) or TOMO (18%), but the contralateral breast mean dose for TOMO (2.48 Gy) was significantly higher than for 3D-CRT (0.93 Gy) or IMRT (1.38 Gy). CONCLUSIONS: Both TOMO and IMRT can significantly reduce cardiac doses, with modest increases in dose to other tissues in left-sided breast cancer patients with unfavorable cardiac anatomy.

Application of holographic display in radiotherapy treatment planning II: a multi-institutional study.

We hypothesized that use of a true 3D display providing easy visualization of patient anatomy and dose distribution would lead to the production of better quality radiation therapy treatment plans. We report on a randomized prospective multi-institutional study to evaluate a novel 3D display for treatment planning.The Perspecta Spatial 3D System produces 360 degrees holograms by projecting crosssectional images on a diffuser screen rotating at 900 rpm. Specially-developed software allows bi-directional transfer of image and dose data between Perspecta and the Pinnacle planning system.Thirty-three patients previously treated at three institutions were included in this IRB-approved study. Patient data were de-identified, randomized, and assigned to different planners. A physician at each institution reviewed the cases and established planning objectives. Two treatment plans were then produced for each patient, one based on the Pinnacle system alone and another in conjunction with Perspecta. Plan quality was then evaluated by the same physicians who established the planning objectives. All plans were viewable on both Perspecta and Pinnacle for review. Reviewing physicians were blinded to the planning device used. Data from a 13-patient pilot study were also included in the analysis.Perspecta plans were considered better in 28 patients (61%), Pinnacle in 14 patients (30%), and both were equivalent in 4 patients. The use of non-coplanar beams was more common with Perspecta plans (82% vs. 27%). The mean target dose differed by less than 2% between rival plans. Perspecta plans were somewhat more likely to have the hot spot located inside the target (43% vs. 33%). Conversely, 30% of the Pinnacle plans had the hot spot outside the target compared with 18% for Perspecta plans. About 57% of normal organs received less dose from Perspecta plans. No statistically significant association was found between plan preference and planning institution or planner.The study found that use of the holographic display leads to radiotherapy plans preferred in a majority of cases over those developed with 2D displays. These data indicate that continued development of this technology for clinical implementation is warranted.

A dosimetric analysis comparing treatment of low-risk prostate cancer with TomoTherapy versus static field intensity modulated radiation therapy.

OBJECTIVES: Static field intensity modulated radiation therapy (IMRT) has demonstrated dosimetric and clinical benefits over 3-dimensional conformal radiation therapy. TomoTherapy is a unique form of IMRT that may offer further improvements. METHODS: The study population consisted of 15 patients with low-risk prostate cancer treated at Rush University with TomoTherapy (n = 7) or IMRT (n = 8). For each patient, both a TomoTherapy plan and an IMRT plan were generated using identical planning objectives. The planning target volume (PTV) was defined as the prostate and proximal seminal vesicles plus a margin. The prescription dose was 7740 cGy in 43 fractions. Radiation Therapy Oncology Group (RTOG) normal tissue guidelines were used as constraints, and the PTV coverage was made equivalent for the paired plans by equalizing the PTV V100. RTOG benchmark DVH values for the rectum and bladder and mean dose to the penile bulb were recorded. The volume of PTV receiving ≥ 105% of the prescription dose was measured. RESULTS: The mean DVH values for each of the RTOG constraints for rectum and bladder were significantly improved using TomoTherapy. The volume of the PTV that received at least 105% of the dose was higher with IMRT (11.7% vs. 0.2%, <0.001). The mean dose to the penile bulb was higher with TomoTherapy (40.4 Gy vs. 27.4 Gy, P = 0.005). CONCLUSIONS: TomoTherapy offers a more favorable dose distribution to the bladder and rectum, as well as improved target homogeneity in comparison with IMRT.

A virtual matching technique for three-field breast irradiation using 3-D planning.

Patients with breast cancer are often treated with radiation to the breast (or chest wall) and draining regional lymph nodes. This is typically performed with a three-field technique in which an anterior supraclavicular field is matched to opposed tangent fields. A single isocenter technique is not always possible. Several techniques have been described to create a perfect match using a conventional simulator. We describe and test a simple, fast and accurate technique to estimate the couch and collimator angles required for a perfect geometric match using 3-D treatment planning software. This method requires no mathematical formulae and is verifiable relative to patient anatomy. An external skin contour is created on the axial slice at the match line and displayed with a 3-D representation. Using a beam's eye view (BEV) of a tangent field, small couch and collimator rotation adjustments are made sequentially until the contour edges are superimposed. The virtual external contour technique was easy to use, gave verification of the match in the BEV and yielded estimates of couch and collimator rotations very close to those calculated using published formulae.

Upright 3D treatment planning using a vertical CT.

In this report, we describe a novel technique used to plan and administer external beam radiation therapy to a patient in the upright position. A patient required reirradiation for thymic carcinoma but was unable to tolerate the supine position due to bilateral phrenic nerve injury and paralysis of the diaphragm. Computed tomography (CT) images in the upright position were acquired at the Northern Illinois University Institute for Neutron Therapy at Fermilab. The CT data were imported into a standard 3-dimensional (3D) treatment planning system. Treatment was designed to deliver 24 Gy to the target volume while respecting normal tissue tolerances. A custom chair that locked into the treatment table indexing system was constructed for immobilization, and port films verified the reproducibility of setup. Radiation was administered using mixed photon and electron AP fields.

A dosimetric comparison of MammoSite and ClearPath high-dose-rate breast brachytherapy devices.

PURPOSE: A new form of partial breast irradiation (PBI), ClearPath (CP) breast brachytherapy, has been introduced. We present our results of a dosimetric comparison of MammoSite (MS) and CP PBI. METHODS AND MATERIALS: The dimensions of the CP device were reconstructed onto the MS planning CT scans for 15 previously treated patients. The mean %V(100), %V(150), %V(200) (percent of the PTV that received 100%, 150%, and 200% of the prescription dose, respectively), ipsilateral breast %V(50) (percent of the ipsilateral normal breast that received 50% of the prescription dose), ipsilateral lung %V(30) (percent of the ipsilateral lung that received 30% of the prescription dose), the heart %V(5) (percent of the heart that received 5% of the prescription dose), and the maximum skin point dose per fraction were then determined for each patient using the two methods of balloon-based PBI. RESULTS: The mean %V(100) was 96.5% vs. 96.5%, the mean %V(150) was 42.1% vs. 42.9% (p=ns), and the mean V(200) was 11.4% vs. 15.2% (p<.05) for the MS and CP methods, respectively. The mean ipsilateral breast %V(50) was 19.8% vs.18.0% (p<.05), the mean ipsilateral lung %V(30) was 3.7% vs. 2.8% (p<.05), the mean heart %V(5) was 57.0% vs. 54.3% (p<.05), and the maximum skin point dose per fraction was 312.2 and 273.6cGy (p<.05) for the MS and CP methods, respectively. CONCLUSIONS: The MS and CP methods of PBI offer comparable target volume coverage; however, the CP device achieves increased normal tissue sparing.

A dosimetric comparison of Xoft Axxent Electronic Brachytherapy and iridium-192 high-dose-rate brachytherapy in the treatment of endometrial cancer.

PURPOSE: This analysis was undertaken to dosimetrically compare iridium-192 high-dose-rate brachytherapy (IB) and Xoft Axxent Electronic Brachytherapy (XB; Xoft Inc., Sunnyvale, CA) in the treatment of endometrial cancer. METHODS AND MATERIALS: The planning CT scans from 11 patients previously treated with IB were used to construct hypothetical treatment plans using the source characteristics of the XB device. The mean V95, V100, and V150 (percent of the planning target volume that received 95%, 100%, and 150% of the prescription dose) were calculated. For both the bladder and rectum, the V35 (percent of the organ that received 35% of the prescription dose) and V50 (percent of the organ that received 50% of the prescription dose) were calculated for each patient using both methods of vaginal brachytherapy. RESULTS: The mean %V95 was 99.7% vs. 99.6% (p = ns) and the mean %V100 was 99.0% vs. 99.1% (p = ns) for the IB and XB methods, respectively. The mean %V150 was 35.8% vs. 58.9% (p < 0.05) for the IB and XB methods, respectively. The mean bladder %V35 was 47.7% vs. 27.4% (p < 0.05) and the mean bladder %V50 was 26.5% vs. 15.9% (p < 0.05) for the IB and XB methods, respectively. The mean rectal %V35 was 48.3% vs. 28.3% (p < 0.05) and the mean rectal %V50 was 27.8% vs. 17.0% (p < 0.05) for the IB and XB methods, respectively. CONCLUSIONS: The IB and XB methods of vaginal brachytherapy offer equivalent target volume coverage; however, the XB method allows increased sparing of the bladder and rectum.

Case report and dosimetric analysis of an axillary recurrence after partial breast irradiation with mammosite catheter.

Partial breast irradiation (PBI) was designed in part to decrease overall treatment times associated with whole breast radiation therapy (WBRT). WBRT treats the entire breast and usually portions of the axilla. The goal of PBI is to treat a smaller volume of breast tissue in less time, focusing the dose around the lumpectomy cavity. The following is a case of a 64-year-old woman with early-stage breast cancer treated with PBI who failed regionally in the ipsilateral axilla. With our dosimetric analysis, we found that the entire area of this axillary failure would have likely received at least 45 Gy if WBRT had been used, enough to sterilize microscopic disease. With PBI, this area received a mean dose of only 2.8 Gy, which raises the possibility that this regional failure may have been prevented had WBRT been used instead of PBI.

A dosimetric comparison of MammoSite high-dose-rate brachytherapy and Xoft Axxent electronic brachytherapy.

PURPOSE: Over 20,000 patients have been treated with partial breast irradiation (PBI) using the MammoSite balloon brachytherapy applicator (IBB). Recently, a new form of balloon-based PBI, Xoft Axxent electronic brachytherapy (KVB), which uses a 50-kV x-ray source, has been introduced. This analysis was undertaken to dosimetrically compare the results of treatment using these two methods of PBI. METHODS AND MATERIALS: The study population consisted of 15 patients previously treated with IBB. The planning CT scans from these 15 patients were used to construct hypothetical treatment plans using the source characteristics of the KVB device. The plans were then compared using the dosimetric parameters discussed below. RESULTS: The mean %V(90) was 99.6% vs. 99.0% (p=nonsignificant [ns]), the mean %V(100) was 96.5% vs. 96.5%, the mean %V(150) was 41.8% vs. 59.4% (p<0.05), the mean %V(200) was 11.3% vs. 32.0% (p<0.05), and the mean %V(300) was 0.4% vs. 6.7% (p<0.05) for the IBB and KVB methods, respectively. The mean ipsilateral breast %V(50) was 19.8% vs. 13.0% (p<0.05), the mean ipsilateral lung %V(30) was 3.7% vs. 1.1% (p<0.05), and the mean heart %V(5) was 59.2% vs. 9.4% (p<0.05) for the IBB and KVB methods, respectively. CONCLUSIONS: The IBB and KVB methods of PBI offer comparable target volume coverage; however, the KVB method is associated with an increased volume of breast tissue in the high-dose regions and a decreased dose to the adjacent normal tissues.

A dosimetric comparison of three-dimensional conformal, intensity-modulated radiation therapy, and MammoSite partial-breast irradiation.

PURPOSE: Limited information is available comparing target volume and normal tissue dosimetry with the different techniques of partial breast irradiation (PBI). We present results of a dosimetric comparison of single catheter, balloon-based brachytherapy using the MammoSite catheter (BRT), 3D conformal radiation therapy (3DCRT), and intensity-modulated radiation therapy (IMRT). METHODS AND MATERIALS: Fifteen patients were treated using the BRT device. With the use of CT scans with balloons in inflated and deflated states, plans were developed for each patient using each of the methods of PBI, for a total of 45 plans. The plans were then compared using the below dosimetric parameters. RESULTS: The mean V100 was 95%, 92%, and 94% for the BRT, 3DCRT, and IMRT techniques, respectively. The mean ipsilateral breast V50 was 29%, 56%, and 46% (p < 0.0001) and the mean ipsilateral lung V30 was 5%, 7%, and 2% (p < 0.001 for IMRT vs. others) for the BRT, 3DCRT, and IMRT methods, respectively. For the 10 patients with left-sided breast tumors, the mean heart V5 was 12%, 4%, and 1% for the BRT, 3DCRT, and IMRT methods, respectively (p < 0.01). CONCLUSIONS: With increasing interest in PBI, our data may help clinicians individualize patient treatment decisions.

Cosmetic outcome and incidence of infection with the MammoSite breast brachytherapy applicator.

We present our results regarding the cosmetic outcome achieved and the rate of infection using the MammoSite breast brachytherapy applicator to treat patients with partial breast irradiation. In addition, factors associated with cosmetic outcome and infection are analyzed. The study population consisted of 30 patients with early stage breast cancer treated using the MammoSite device from October 28, 2002, to February 13, 2004. Cosmetic outcome was analyzed for its association with the following parameters: volume of the balloon, balloon-to-skin distance, maximal skin point dose per fraction, V100 (percent of volume that received 100% of the prescription dose), V150 (percent of volume that received 150% of the prescription dose), and V200 (percent of volume that received 200% of the prescription dose). The occurrence of infection at the time of treatment and during follow-up was also recorded. At a median follow-up of 13 months (range 1-16 months), 53.3% of the patients (16/30) were reported to have an excellent cosmetic outcome and 40.0% (12/30) had a good cosmetic outcome. Excellent cosmetic outcome was associated with a greater mean balloon-to-skin distance compared to those who achieved a good cosmetic outcome (1.5 cm versus 1.2 cm) (p = 0.164). The mean V100, V150, and V200 of those in the excellent cosmetic outcome group were 92.1%, 34.5%, and 7.6% versus 93.0%, 34.7%, and 7.6% in the good cosmetic outcome group (p = 0.642, 0.926, and 0.853), The mean balloon volumes were 47.7 cm3 and 56.9 cm3, respectively (p = 0.063) in the excellent and good outcome groups. The mean maximal skin doses per fraction in the excellent and good outcome groups were 354.8 cGy and 422.3 cGy (p = 0.286), respectively. Infection occurred in 13.3% of the patients (4/30). An excellent or good cosmetic outcome was achieved in 93.3% of patients and infection occurred in 13.3% of patients treated with the MammoSite breast brachytherapy applicator. Excellent cosmetic outcome was associated with a greater balloon-to-skin distance, lower maximal skin dose per fraction, and smaller mean balloon volume; however, the results did not reach statistical significance.

Limited accuracy of dose calculation for large fields at deep depths using the BrainSCAN v5.21 treatment planning system.

The Varian 120 multileaf collimator (MLC) has a leaf thickness of 5 mm projected at the isocenter plane and can deliver a radiation beam of large field size (up to 30 cm) to be used in intensity-modulated radiotherapy (IMRT). Often the dose must be delivered to depths greater than 20 cm. Therefore, during the commissioning of the BrainSCAN v5.21 or any radiation treatment-planning (RTP) systems, extensive testing of dose and monitor unit calculations must encompass the field sizes (1 cm to 30 cm) and the prescription depths (1 cm to 20 cm). Accordingly, the central-axis percent depth doses (PDDs) and off-axis percentage profiles must be measured at several depths for various field sizes. The data for this study were acquired with a 6-MV X-ray beam from a Varian 2100EX LINAC with a water phantom at a source-to-surface distance (SSD) of 100 cm. These measurements were also used to generate a photon beam module, based on a photon pencil beam dose-calculation algorithm with a fast-Fourier transform method. To commission the photon beam module used in our BrainSCAN RTP system, we performed a quantitative comparison of measured and calculated central-axis depth doses and off-axis profiles. Utilizing the principles of dose difference and distance-to-agreement introduced by Van Dyk et al. [Commissioning and quality assurance of treatment planning computers. Int J Radiat Oncol Biol Phys. 1993; 26:261-273], agreements between calculated and measured doses are <2% and <2 mm for the regions of low- and high-dose gradients, respectively. However, large errors (up to approximately 5% and approximately 7% for 20-cm and 30-cm fields, respectively, at the depth 20 cm) were observed for monitor unit calculations. For a given field size, the disagreement increased with the depth. Similarly, for a given depth the disagreement also increase with the field size. These large systematic errors were caused by using the tissue maximum ratio (TMR) in BrainSCAN v5.21 without considering increased field size as depth increased. These errors have been reported to BrainLAB.

The MammoSite breast brachytherapy applicator: a review of technique and outcomes.

The MammoSite breast brachytherapy device was designed to overcome the potential scheduling problems associated with external beam radiotherapy (EBRT) and the technical difficulties of multi-catheter-based interstitial brachytherapy. The device consists of a silicone balloon connected to a catheter which contains an inflation channel and a port for passage of a high-dose-rate brachytherapy source. The American Brachytherapy Society and American Society of Breast Surgeons have published partial breast irradiation (PBI) patient selection guidelines. The MammoSite applicator has been shown in two dosimetric studies to treat a comparable volume to multicatheter-based interstitial implants. The MammoSite catheter can be placed at the time of lumpectomy or in a separate procedure using ultrasound guidance. Four optimization methods have been described: the single point method, the six prescription point method (RUSH Technique), the University of Southern California Norris Cancer Center Method, and the Surface Optimization Technique. An excellent or good cosmetic outcome has been reported in 80% to 93% of patients at 1 year in most studies. Cosmetic results appear highly related to skin spacing. The MammoSite applicator has been associated with early side effects comparable with traditional breast conserving therapy. A NSABP trial will randomize patients to either whole breast irradiation or PBI consisting of interstitial brachytherapy, MammoSite brachytherapy, or 3D conformal radiation.

Dose perturbation induced by radiographic contrast inside brachytherapy balloon applicators.

Phantom measurements and Monte Carlo calculations have been performed for the purpose of characterizing the dose perturbation caused by radiographic contrast inside the MammoSite breast brachytherapy applicator. Specifically, the dose perturbation is quantified as a heterogeneity correction factor (HCF) for various balloon radii and contrast concentration levels. The dose perturbation is larger for larger balloon radii and higher contrast concentrations. Based on a validated Monte Carlo simulation, the calculated HCF values are 0.99 for a 2 cm radius balloon and 0.98 for a 3 cm radius balloon at 6% contrast concentration levels, and 0.89 and 0.87 for 2 and 3 cm radius balloons, respectively, at 100% contrast concentrations. For a typical implanted balloon radius of 2.4 cm, the HCF values decrease from 0.99 at 6% contrast concentration to 0.90 at 100% contrast concentration. For balloons implanted in patients at our institution, the mean HCF is 0.99, corresponding to a dose reduction of approximately 1%. The contrast effect results in a systematic reduction in the delivered dose, therefore the minimal amount of radiographic contrast necessary should be used.

Dosimetric characteristics of the Leipzig surface applicators used in the high dose rate brachy radiotherapy.

The nucletron Leipzig applicator is designed for (HDR) 192Ir brachy radiotherapy of surface lesions. The dosimetric characteristics of this applicator were investigated using simulation method based on Monte Carlo N-particle (MCNP) code and phantom measurements. The simulation method was validated by comparing calculated dose rate distributions of nucletron microSelectron HDR 192Ir source against published data. Radiochromic films and metal-oxide-semiconductor field-effect transistor (MOSFET) detectors were used for phantom measurements. The double exposure technique, correcting the nonuniform film sensitivity, was applied in the film dosimetry. The linear fit of multiple readings with different irradiation times performed for each MOSFET detector measurement was used to obtain the dose rate of each measurement and to correct the source transit-time error. The film and MOSFET measurements have uncertainties of 3%-7% and 3%-5%, respectively. The dose rate distributions of the Leipzig applicator with 30 mm opening calculated by the validated MC method were verified by measurements of film and MOSFET detectors. Calculated two-dimensional planar dose rate distributions show similar patterns as the film measurement. MC calculated dose rate at a reference point defined at depth 5 mm on the applicator's central axis is 7% lower than the film and 3% higher than the MOSFET measurements. The dose rate of a Leipzig applicator with 30 mm opening at reference point is 0.241+/-3% cGy h(-1) U(-1). The MC calculated depth dose rates and profiles were tabulated for clinic use.