Open MR-guided high-dose-rate (HDR) prostate brachytherapy: feasibility and initial experiences

in Pathology Oncology Research (2011), 17(2), 315-24

The aim of our pilot study was to demonstrate the feasibility and dosimetric quality of MR-guided HDR prostate brachytherapy in a low-field 0.35T open MRI scanner and to present our initial clinical ... [more ▼]

The aim of our pilot study was to demonstrate the feasibility and dosimetric quality of MR-guided HDR prostate brachytherapy in a low-field 0.35T open MRI scanner and to present our initial clinical experiences. 16 patients with intermediate- to high-risk localized prostate cancer were treated with 46-60 Gy of external beam radiotherapy preceded and/or followed by an 8 Gy MR-guided HDR boost. For interventions an MR compatible custom-made system, coaxial needles and plastic catheters were used. Template reconstruction, trajectory planning, image guidance, contouring and treatment planning were exclusively based on MR images. For treatment planning, dose-point- and anatomy-based inverse planning optimization was used. Image quality was found to be good to excellent in almost all cases. The mean catheter placement accuracy modeled by Rayleigh distribution was 2.9 mm with a sigma value of 2.3 mm. The mean and standard deviation (SD) of the dosimetric results for the target volume were the following: V100: 94.2 ± 4.3%, V150: 43.9 ± 6.8%, V200: 18.5 ± 5.9%. The mean D(0.1), D(1) and D1 values for the intraprostatic urethra were 117.6 ± 12.5%, 98.5 ± 19.9% and 122.3 ± 16.4%, respectively. Regarding the rectal wall the mean D(0.1), D(1) and D(2) values were 77.3 ± 7.2%, 64.8 ± 7.5%, and 53.2 ± 9.1%, respectively. The mean maximum dose for the inner rectal surface was 53.5 ± 9.2%. No RTOG Grade 3 or worse acute toxicities were observed. Our method seems to be a promising approach for performing feasible, accurate and high-quality MR-guided HDR prostate brachytherapy. To determine the long term side effects and outcome higher number of patients, additional follow-up is needed. [less ▲]

3-D conformal photon boost in the treatment of early stage breast cancer: four year follow up results.

in Pathology Oncology Research (2011), 17(1), 17-23

In the treatment of early stage breast cancer, breast conserving surgery (BCS) followed by whole breast irradiation (WBI) is the standard treatment. The impact of the tumor bed boost following WBI is well ... [more ▼]

In the treatment of early stage breast cancer, breast conserving surgery (BCS) followed by whole breast irradiation (WBI) is the standard treatment. The impact of the tumor bed boost following WBI is well-defined, but there are various delivery methods. In this study we demonstrate our 4 year experience with the 3-D conformal boost technique. Between January 2004 and June 2005, 77 early stage (Stage I-II) breast cancer patients were treated in our institute with whole breast irradiation (WBI, 50.4 Gy in 28 fractions) after breast conserving surgery. Following WBI, 3-D conformal photon boost was delivered (10-16 Gy in five to eight fractions) for all patients. The clinical outcome was retrospectively recorded in terms of survival and local control. The side effect profile (fibrosis, fat necrosis and cosmetic outcome) was also recorded and studied. In our patient group the mean follow up time was 46.8 months (median: 52, range: 17-71, SD: 14.4) The 4-year probability of local tumor control was 96% (crude rate: 74/77-96.1%), the 4-year probability of overall survival was 96% (crude rate: 74/77-96.1%) in this patient group. In case of the distant metastasis free survival the probability was 89, 5% (crude rate: 70/77-90, 1%). Probability of disease specific survival was 98% (crude rate: 76/77-98. 7%). Local relapse occurred in three cases (3.9%). In ten cases (12.9%) asymptomatic grade I-II breast fibrosis, in eight cases (10.4%) asymptomatic breast fat necrosis were registered. For 14 patients (18.2%) asymptomatic lung fibrosis was recorded on the control CT scans. In term of the relapse free survival, the close resection margin and the nodal positivity resulted in significant difference in favor of the clear resection margin group and the node negative group. In this study the 3-D conformal photon boost resulted in good local control and side effect profile. The presence of tumor bed clips resulted in significantly lower boost PTV volumes, but no correlation was found between the irradiated boost volume and the breast fibrosis. In the relapse free survival analysis, nodal negativity and clear margin status resulted in significantly better RFS. [less ▲]

Technical feasibility of transperineal MR-guided prostate interventions in a low-field open MRI unit: canine study.

in Pathology Oncology Research (2009), 15(3), 31522

Magnetic resonance imaging (MRI) provides superior visualization of the prostate, its substructure, surrounding tissues, and, most important, focal lesions or cancer. The purpose of our canine study was ... [more ▼]

Magnetic resonance imaging (MRI) provides superior visualization of the prostate, its substructure, surrounding tissues, and, most important, focal lesions or cancer. The purpose of our canine study was to demonstrate the feasibility of a low-field (0.35 T) transperineal system that enables precise MR image guidance of prostate interventions. The canines were placed in the right lateral decubitus position. Template reconstruction, trajectory planning, contouring were based on T2-weighted FSE images. For image guidance and target confirmation, fast gradient spoiled-echo (FSPGR) sequence was used. MR compatible coaxial needles were manually inserted through the perineum to the base of the prostate. After satisfactory position was confirmed, brachytherapy catheters were placed through the coaxial needles. The mean deviation of the needle displacements was 2.9 mm with a median value of 2.7 mm. 97% of the errors were less than 4.0 mm. The needle placement accuracy was modelled by the Rayleigh distribution with a sigma value of 2.3 mm. Visual confirmation of needle placements was demonstrated on pathology tissue slices. The time needed for each step was: anaesthesia - 15 min, setup and positioning - 15 min, initial imaging - 15 min, template registration, projection - 15 min, contouring, trajectory planning, insertion of 12 needles - 60 min Based on our canine experiences our method seems to be a promising approach for performing feasible, accurate, reliable and high-quality prostate MR guidance within a reasonable time span. [less ▲]

Comparison of photon with electron boost in treatment of early stage breast cancer

in Pathology Oncology Research (2008), 14(2), 193-7

In the treatment of early stage breast cancer breast conserving surgery (BCS) followed by whole breast irradiation (WBI) is a standard method. The impact of the tumor bed boost following WBI is well ... [more ▼]

In the treatment of early stage breast cancer breast conserving surgery (BCS) followed by whole breast irradiation (WBI) is a standard method. The impact of the tumor bed boost following WBI is well-defined, but there are various delivery methods. In this study the electron and the photon boost techniques were compared. For 78 early stage breast cancer patients both CT based 3D conformal photon boost and electron boost plans were created. For dosimetric comparison coverage index (CI), external volume index (EI) and conformality index (COIN) were studied. Lung volume receiving a dose of 2 Gy was also reviewed. Seventy-eight patients with 156 plans were compared. The mean tumor bed volume was measured as 61.39 cm3 the mean tumor bed-skin distance was 3.13 cm. In the case of CI and COIN significant differences were found in favor of the photon boost. In the comparison of EI no significant difference was detected between the two techniques. The mean lung volume receiving 2 Gy were 42.3 and 168.35 cm3, for photons and electrons respectively. In the adjuvant treatment of early stage breast cancer WBI followed by conformal photon boost showed to be superior to electron boost in focus of the COIN and CI. [less ▲]

Az MR-képalkotással vezérelt prostata-brachytherapia metodikai tervezése

in Magyar Radiologia (2007), 81(5-6), 224-229

Application of MRI for improved local control in complex radiotherapy of cervical cancer

in Archive of Oncology (2006), 14(3-4), 95-100

Background: The aim of this study was to analyze the use of magnetic resonance imaging (MRI) as a modern medical imaging technique in radiotherapy with special emphasis on the integration of MRI and a ... [more ▼]

Background: The aim of this study was to analyze the use of magnetic resonance imaging (MRI) as a modern medical imaging technique in radiotherapy with special emphasis on the integration of MRI and a novel technique in brachytherapy to optimize treatment outcome in cervical cancer. Methods: In addition to the CT based shrinking volume conformal teletherapy in 31 patients with locally advanced cervical cancer, MRI examination with a special adjustable applicator at the treatment site was performed for the brachytherapy planning. To avoid excessive doses to the healthy structures during complex cervical radiotherapy isodose curves were calculated upon the information of the MR image and dose distribution was evaluated. Results: The consecutive application of CT and MRI limited the possibility for overdosage of the critical organs and undertreatment of the advanced tumor spread in all cases. The overall response rate for the complex treatment was 74.2% with complete regression in 25.8% of the cases. Based on the exact information of the three dimensional digital data radiation doses could be optimized without increasing the possibility of acute complications rate. Conclusion: The introduction of 3D treatment planning for teletherapy pelvic and boost irradiation of cervical carcinoma as well as for the brachytherapy part of the complex treatment is to be recommended. [less ▲]