[Permanent implant brachytherapy for early, organ-confined prostate cancer]. / Permanens implantációs prosztata-brachyterápia korai, szervre lokalizált prosztatarák kezelésére.

PURPOSE: Implementation of permanent prostate implant (PPI) brachytherapy in Hungary and presentation of initial experience. PATIENTS AND METHODS: Between December 2008 and 2010, thirty-nine patients with low (n=26) and intermediate (n=13) risk prostate cancer were treated with PPI. Their mean age and initial PSA were 66 year (51-80 year) and 9 ng/ml (3,2-15 ng/ml). Iodine-125 loose seeds were implanted under spinal anaesthesia using the FIRST system (Nucletron, The Netherlands). Needles were inserted into the prostate through the perineum according to the preplan based on transrectal ultrasound images. The treatment plan was modified according to updated positions of the needles on live US images. The prescribed dose to the prostate was 145 Gy. Seed loading was performed under real-time US assistance. Implanted sources were checked by X-ray and CT images. Patients were discharged one day after the implantation. On follow-up visits PSA and toxicity were registered. RESULTS: The mean follow-up was 10 months (3-27 months), the median number of seeds was 53 (30-78), their mean activity was 0.48 mCi (0.41-0.52 mCi). The mean coverage of the prostate by the prescribed dose was 96% (92-98%). The mean percent dose of the prescribed dose that covered the 90% of the prostate (D90), 2 cm3 of the rectum (Dr2cm3) and 10% of the urethra (Du10) were 113% (104-121%), 85% (48-121%) and 124% (98-146%) respectively. Deviation from the requested dose-volume constraints never exceeded 3%. Acute >grade 2 proctitis, grade 2 and 3 cysto-prostatitis were observed in 0 (0%), 13 (33.3%) and 1 (2.6%) cases. Biochemical relapse occurred in one patient (2.6%). CONCLUSION: This is a report of the first application of PPI in Hungary. The observed rate of acute proctitis was negligible, the rate and severity of acute cysto-prostatitis was tolerable. With the use of intraoperative planning, dose distributions met the dose-volume constraints in most of the cases. The biochemical control is excellent but the follow-up time is still short.

[Fifty-year-old history of cobalt radiotherapy in Hungary]. / Otvenéves a telekobalt-terápia Magyarországon.

The first patient in Hungary was treated by cobalt therapy fifty years ago at the National Institute of Oncology with a Gravicert type equipment. On the occasion of this anniversary, the 50-year history of the Hungarian cobalt therapy is reviewed, and its present role is discussed. The first cobalt unit (Gravicert) was designed by László Bozóky seven years after the first cobalt unit installation in the world in Canada. The megavoltage energy of the Co-60 source (average: 1.25 MeV) resulted in more successful treatments of deep-seated tumors compared to the X-ray therapy. In the next two-three decades, until the widespread use of the high-energy linear accelerators, the Co-60 teletherapy meant the modern radiation treatment throughout the world. Improvements of quality in radiation techniques necessitated exact localization of the tumors and developments of treatment planning methods. At the beginning, the localization was performed with X-ray machines, while the treatment planning was done manually. In 1965 a Rotacert type cobalt unit was installed at our institute. This machine was already capable of making irradiation in multiple directions and it worked in rotating mode, too. In Hungary, more cobalt units - first the Gravicert type, then foreign made machines - were gradually installed in other radiotherapy centers too. The quality of treatments was significantly improved by the introduction of the computerized treatment planning, and the foundation of the IAEA-supported National Treatment Planning Network in 1978 was an important step in this process. The next important development was the commencement of the CT image based treatment planning in 1981. With the spread of modern linear accelerators the role of the cobalt units has greatly decreased by now, however, nearly 2,500 cobalt units are still in use worldwide. Their usage could be further increased with technical developments. At present, radiation treatments are performed with cobalt units in eight out of twelve radiotherapy centers in Hungary.

[Computerized radiotherapy planning: retrospective analysis and current methods]. / Számítógépes besugárzástervezés: visszatekintés és korszeru módszerek.

PURPOSE: To present the development of treatment planning methods at the National Institute of Oncology (NIO) from 1969 till 2005. METHODS: The methods and devices of treatment planning is described chronologically. RESULTS: First we did the treatment planning with in-house made devices: body contour drawing instrument, simplified anatomical cross sections, treatment planning table for the cross section projection, archives of isodose curves adjusted to body contours, etc. It was a significant improvement when the graphical addition of isodose curves was followed by computerized dose calculation. In 1978 the work of the Computerized National Treatment Planning Network was started. The Network was organized by IAEA, Ministry of Health Hungary and NIO. The modern treatment planning started at NIO in 1981. From this year, the treatment planning was based on CT, using the CT apparatus of the Medical Postgraduate University. In 1991 a Siemens MEVAPLAN treatment planning system was installed at NIO. The CT data were transferred to the system via floppy disk. The 3D treatment planning program (Pinnacle software of ADAC) started in 2000. The CT, the treatment planning system and newer linear accelerators are connected through the computerized radiotherapy network. Patient positioning, fixing and control devices (mask, EPID etc.) increased the efficacy of the treatment. In-house made devices help this aim too: mirrors at the linear accelerators, special skin marks for CT, block verification unit, multileaf collimator for x-ray treatment simulator. In this year the intensity-modulated radiotherapy (IMRT) will be started at NIO. CONCLUSIONS: The treatment planning at NIO developed to high degree during the investigated time, and it had a considerable effect on the efficacy of radiotherapy.

[Dosimetric assessment of external treatment plans for breast cancer: the significance of dose prescription selection]. / Emlodaganatos betegek külso besugárzási terveinek dozimetriai vizsgálata: a dóziseloírás megválasztásának jelentosége.

PURPOSE: To analyze the treatment plans of breast irradiation performed with two tangential beams, to discuss the importance of dose prescription, and to estimate the differences in delivered dose due to various dose prescription methods. MATERIAL AND METHODS: A survey was performed between the Hungarian radiotherapy centers in order to compare the dose prescription methods. Then, treatment plans of 125 breast cancer patients treated in our department were evaluated. The irradiations were performed with cobalt unit, and with 6 and 9 MV photon beams of linear accelerators. The dose distributions were normalized to izocenter, then dose values in five points in central plane; local medial, lateral and central maximums (D(med), D(lat) and D(cent)); volumetric maximum and its location were determined. To characterize the dose to lung and to heart at left-sided tumors the central lung distance (CLD) and maximum heart distance (MHD) were used. Based on the results, estimation was made to assess the differences between delivered dose due to various dose prescriptions applied at the institutions. RESULTS: Four types of dose prescription are currently used in our country, and most frequently the isocenter is selected as a reference point. In the central plane the calculated dose in all but one points differed only a little from the dose to isocenter. The mean D(med), D(lat) and D(cent) were 107%, 107% and 101%, respectively. The volumetric maximum was on average 13% higher than the dose to isocenter. Regarding the beam qualities, this value was 16%, 13% and 11% for cobalt unit, 6 MV and 9 MV photon beams, respectively. The mean CLD and MHD were 1.9 and 0.8 cm, respectively. The difference between delivered doses at the institutions was 6% on average, but in extreme cases it can be as high as 20%. CONCLUSIONS: Three-dimensional treatment planning and plan evaluation are recommended at breast irradiation, especially for large breasts. Since the various dose prescriptions may result in significant differences in the delivered doses, use of a standard dose prescription protocol is recommended.

[The possibility of the use of MRI images in the three-dimensional external radiotherapy treatment planning]. / MRI-képek használatának lehetôsége a háromdimenziós külsô besugárzástervezésben.

PURPOSE: To review the application of MRI images in the radiation treatment planning,to discuss the advantages and disadvantages of MR imaging with respect to treatment planning, and to investigate the geometric distortion. METHODS: Humanoid therapy phantom was used for MRI and CT scanning, and distances between markers inside and on the surface of the phantom were measured in order to quantify the geometric distortion. The procedure of MRI/CT image fusion, which makes it possible to use the data of both imaging modalities for treatment planning, was described. RESULTS: At small volumes (head phantom) the geometric distortion was negligible (<2 mm), but at large volumes (eg. pelvis) remarkable geometric inaccuracies were observed. For example, the width of the pelvis measured in the MRI images was 7 mm less than the real distance, which corresponds to 2% inaccuracy. Geometric distortion was observed not only in the axial, but also in the sagittal and coronal planes. We have found that the geometric error increases with the distance measured from the magnetic isocenter. When the geometric distortion is not significant, the MRI/CT image fusion can be carried out reliably with the use of surface markers. CONCLUSIONS: At small volumes the MRI images can be used for treatment planning after their fusion with CT images. At larger volumes the geometric distortion without any correction may preclude the MRI images from using them in the treatment planning. A detailed assessment of geometric distortion must be carried out before the introduction of MRI images into the radiation treatment planning.