Dan Josefsson

Are IMRT treatments in the head and neck region increasing the risk of secondary cancers

Abstract Background. Intensity-modulated radiation therapy (IMRT) has been increasingly employed for treating head and neck (H&N) tumours due to its ability to produce isodoses suitable for the complex anatomy of the region. The aim of this study was to assess possible differences between IMRT and conformal radiation therapy (CRT) with regard to risk of radiation-induced secondary malignancies for H&N tumours. Material and methods. IMRT and CRT plans were made for 10 H&N adult patients and the resulting treatment planning data were used to calculate the risk of radiation-induced malignancies in four different tissues. Three risk models with biologically relevant parameters were used for calculations. The influence of scatter radiation and repeated imaging sessions has also been investigated. Results. The results showed that the total lifetime risks of developing radiation-induced secondary malignancies from the two treatment techniques, CRT and IMRT, were comparable and in the interval 0.9–2.5%. The risk contributions from the primary beam and scatter radiation were comparable, whereas the contribution from repeated diagnostic imaging was considerably smaller. Conclusion. The results indicated that the redistribution of the dose characteristic to IMRT leads to a redistribution of the risks in individual tissues. However, the total levels of risk were similar between the two irradiation techniques considered.

Respiratory gating for proton beam scanning versus photon 3D-CRT for breast cancer radiotherapy

Abstract Background Respiratory gating and proton therapy have both been proposed to reduce the cardiopulmonary burden in breast cancer radiotherapy. This study aims to investigate the additional benefit of proton radiotherapy for breast cancer with and without respiratory gating. Material and methods Twenty left-sided patients were planned on computed tomography (CT)-datasets acquired during enhanced inspiration gating (EIG) and free-breathing (FB), using photon three-dimensional conformal radiation therapy (3D-CRT) and scanned proton beams. Ten patients received treatment to the whole breast only (WBO) and 10 were treated to the breast and the regional lymph nodes (BRN). Dosimetric parameters characterizing the coverage of target volumes and the cardiopulmonary burden were compared using a paired, two-tailed Student’s t-test. Results Protons ensured comparable or better target coverage than photons in all patients during both EIG and FB. The heterogeneity index decreased from 12% with photons to about 5% with protons. The mean dose to the ipsilateral lung was reduced in BRN patients from 12 Gy to 7 Gy  (RBE) in EIG and from 14 Gy to 6–7 Gy (RBE) in FB, while for WBO patients all values were about 5–6 Gy (RBE). The mean dose to heart decreased by a factor of four in WBO patients [from 1.1 Gy to 0.3 Gy (RBE) in EIG and from 2.1 Gy to 0.5 Gy (RBE) in FB] and 10 in BRN patients [from 2.1 Gy to 0.2 Gy (RBE) in EIG and from 3.4 Gy to 0.3 Gy (RBE) in FB]. Similarly, the mean and the near maximum dose to the left anterior descending artery (LAD) were significantly lower (p < 0.05) with protons in comparison with photons. Conclusion Proton spot scanning has a high potential to reduce the irradiation of organs at risk and other normal tissues for most patients, beyond what could be achieved with EIG and photon therapy. The largest dose sparing has been seen for BRN patients, both in terms of cardiopulmonary burden and integral dose.

Impact of physiological breathing motion for breast cancer radiotherapy with proton beam scanning – An in silico study

This study investigates the impact of breathing motion on proton breast treatment plans. Twelve patients with CT datasets acquired during breath-hold-at-inhalation (BHI), breath-hold-at-exhalation (BHE) and in free-breathing (FB) were included in the study. Proton plans were designed for the left breast for BHI and subsequently recalculated for BHE or designed for FB and recalculated for the extreme breath-hold phases. The plans were compared from the point of view of their target coverage and doses to organs-at-risk. The median amplitude of breathing motion determined from the positions of the sternum was 4.7mm (range 0.5-14.6mm). Breathing motion led to a degradation of the dose coverage of the target (heterogeneity index increased from 4-7% to 8-11%), but the degraded values of the dosimetric parameters of interest fulfilled the clinical criteria for plan acceptance. Exhalation decreased the lung burden [average dose 3.1-4.5Gy (RBE)], while inhalation increased it [average dose 5.8-6.8Gy (RBE)]. The individual values depended on the field arrangement. Smaller differences were seen for the heart [average dose 0.1-0.2Gy (RBE)] and the LAD [1.9-4.6Gy (RBE)]. Weak correlations were generally found between changes in dosimetric parameters and respiratory motion. The differences between dosimetric parameters for various breathing phases were small and their expected clinical impact is consequently quite small. The results indicated that the dosimetric parameters of the plans corresponding to the extreme breathing phases are little affected by breathing motion, thus suggesting that this motion might have little impact for the chosen beam orientations with scanned proton beams.

Potential Benefit of Scanned Proton Beam versus Photons as Adjuvant Radiation Therapy in Breast Cancer

Abstract Purpose: To investigate the feasibility of using scanned proton beams as adjuvant radiation therapy for breast cancer. Long-term cardiopulmonary complications may worsen the quality of life and reduce the positive contribution of radiation therapy, which has been known to improve long-term control of locoregional disease as well as the long-term survival for these patients. Materials and Methods: Ten patients with stage I-III cancer (either after mastectomy or lumpectomy, left- or right-sided) were included in the study. The patients were identified from a larger group where dose heterogeneity in the target and/or hotspots in the normal tissues qualified them for irregular surface compensator planning with photons. The patients underwent planning with 2 scanned proton beam planning techniques, single-field uniform dose and intensity-modulated proton therapy, and the results were compared with those from irregular surface compensator. All volumes of interest were delineated and reviewed by experie...

Radioactivity Exploration from the Arctic to the Antarctic. Part 6: The Arctic Ocean-96 expedition

The Swedish Arctic Ocean-96 expedition arranged by the Swedish Polar Research Committee took place during 1996 with the Swedish icebreaker M/S Oden. The expedition focused on studying the distribution of radionuclides in different water masses in the central Arctic Ocean. The expedition crossed the Barents Sea, entered the Nansen Basin at the St. Anna Trough, and continued north across the Amundsen Basin. The main part of the expedition was concentrated on the north Lomonosov Ridge and the return route passed the North Pole and went south along 10 oE towards Svalbard. In both legs, water samples in the surface and subsurface layers were collected for the determination of fission products and transuranic elements in seawater and sediment. The highest 137Cs, 90Sr and 129l activities and 134Cs/137Cs activity ratios are found in a band stretching from the northern Lomonosov Ridge, over the North Pole and south along 10-15 oE to 85 oN. The releases from European nuclear fuel reprocessing plants and Chernobyl fallout traced by the 129I and 134Cs/137Cs signals respectively have approximately the same spatial distribution in the Arctic Ocean surface layer. The activity concentration of 90Sr in surface water is about 2 Bq.m-3. For 239+240Pu the lowest concentrations in the surface water of 4 mBq.m-3 was found on the Lomonosov Ridge and in the Makarov Basin. In the Eurasian Basin, the concentrations 239+240Pu are about 13 mBq.m-3 . For all the radionuclides analysed, the water profiles generally show activities decreasing with depth. An exception is the high 137Cs activity concentrations found in the lower halocline layer at the Lomonosov Ridge and Makarov Basin stations. The maxima were not observed in the 90Sr or l29l measurements. It is assumed to be due to a contribution of Chernobyl fallout to the Arctic Ocean surface layers in the years around 1990. Inventories down to 900 m death reveal that between 60-70 % of the 137Cs, 90Sr and in the Arctic Ocean water, are present in the surface layer inflow from the Atlantic. The total inventories down to 900 m in the Eurasian Basin of the Arctic Ocean estimate to 6.7 PBq for 137Cs, 3.4 PBq for 90Sr and 5.3x1028 atoms for 129l. (Less)

EP-1762: Impact of physiological breathing motion for breast cancer radiotherapy proton beam scanning

Material and Methods: The study cohort was composed of twelve thoracic patients who had CT-datasets acquired during breath-hold at inhalation phase, breath-hold at exhalation phase and in free breathing mode. Proton treatment plans were designed for the left breast for the breath-hold at inhalation phase and were subsequently recalculated for the breath-hold at exhalation phase. Similarly, plans devised for the CT acquired in free breathing mode were recalculated for the extreme breath-hold phases. Four different field arrangements were used for each patient: two plans with three fields and two with one field. The dosimetric features of the plans were compared from the point of view of their coverage of the target and the doses to the organs at risk.

Radioactivity Exploration from the Arctic to Antarctica. Part 5: The Tundra-94 expedition

The joint Swedish-Russian “Tundra Ecology-94” expedition during 1994 used the large Russian ice-breaking research vessel R/V Akademik Fedorov a platform and went along a coastline of 3500 km-from the Kola Peninsula 10°E to Kolyuchinskaya Bay 173°E. Radioactivity in air, seawater and sediment was explored at various locations along the route. The average of 7Be activity concentration in air over the Arctic Ocean was found to be only about 0.6 mBq.m-3, in air close to the Siberian coast-line, however, it was as high as 11 mBq.m-3. The activity concentration of 210Pb in the air over the Arctic Ocean varies between 37 – 176 micro-Bq.m-3. In the air close to the Siberian coastline 71oN 84oE, however, the activity concentration of 210Pb in the air was much higher, about 2500 micro.Bq.m-3. Anthropogenic radioactivity in the Arctic originate from nuclear weapons fallout, release from nuclear fuel reprocessing plant, and from the Chernobyl accident. The minimum values of the 137Cs activity concentration water along the route of the Tundra were found in South-eastern Barents Sea: 5.3 Bq.m-3 of surface-water, and of bottom-water 6.4 Bq.m-3. Maximum values were found in the Western Laptevsea: 12.8 Bq.m-3 of surface-water, and of bottom-water 5.1 Bq.m-3. East of 150 oE the 134Cs / 137Cs ratios are less than 0.003, indicating that less than 6% of the 137Cs originated from the Chernobyl accident. 137Cs levels are reduced to values of about 1.4 Bq.m-3 in the low salinity water near the mouths of the Ob and Yenisey Rivers. The 134Cs / 137Cs activity ratio of 0.014 in the freshwater indicates that the Chernobyl component in the river systems is the same (30%) as in the marine waters west of 150 oE. In surface water the 90Sr activity concentration range from 2 to 4 Bq.m-3, Maximuim values about 3.5 Bq.m-3 were found between 100-140 oE. But east of 150 oE the values decreased to about 0.5 Bq.m-3 at 170 oE. In bottom water the 90Sr activity concentration range from 1.5 at 40 oE to maximum values about 4 Bq.m-3 between 100-120 oE. . The measured 90Sr/137Cs ratios in surface water close to a value of 0.14 over a wide range of stations from the Barents to the Laptev Seas. The 129I concentration in sea-water along the route of the Tundra expedition decrease from about 20·1011 atoms.l-1 at 40 oE, to about 1·1011 atoms.l-1 east of 160 oE. The 239+240Pu activity concentration in surface seawater decrease from about 10 mBq.m-3 to about 1 mBq.m-3 east of 160 oE. In bottom seawater it is more evenly distributed between 10-4 mBq.m-3, with minimum at 60-80 oE and maxima at 40oE and 160 oE. Measured 238Pu/239,240Pu activity ratios in the water column yield no evidence of any leakage of plutonium from dumped nuclear wastes in the Kara and Barents Seas. (Less)