Determination of Whole-Body and Lens Dose Conversion Factors for Japanese Field Mice, Apodemus Speciosus

The 11 March 2011 Fukushima nuclear accident in Japan resulted in widespread radioactive contamination within the 20 km evacuation zone. Japanese field mice (Apodemus speciosus) living within the contaminated region received radiation doses from external environmental contamination as well as internally deposited radionuclides. Cataract formation in the lens of eyes of these mice is a possible deterministic effect of ionizing radiation; however, determination of actual doses is difficult. Since no dose conversion factors currently exist for the lens of the eyes of Japanese field mice, lens dose conversion factors were created using a Monte Carlo N-Particle simulation and compared to the International Commission on Radiological Protection Publication 108 reference rat whole-body dose conversion factors. Monte Carlo N-Particle simulations included doses to the lens of the eyes from external sources (received while both above and below ground), as well as doses from internal contamination. Although the Publication 108 reference rat is almost twice the average mass of the Japanese field mouse, all dose conversion factor calculations using Monte Carlo N-Particle methods were within approximately 37% of the Publication 108 values for the reference rat.

An interlaboratory comparison of dosimetry for a multi-institutional radiobiological research project: Observations, problems, solutions and lessons learned

PURPOSE

An interlaboratory comparison of radiation dosimetry was conducted to determine the accuracy of doses being used experimentally for animal exposures within a large multi-institutional research project. The background and approach to this effort are described and discussed in terms of basic findings, problems and solutions.

METHODS

Dosimetry tests were carried out utilizing optically stimulated luminescence (OSL) dosimeters embedded midline into mouse carcasses and thermal luminescence dosimeters (TLD) embedded midline into acrylic phantoms.

RESULTS

The effort demonstrated that the majority (4/7) of the laboratories was able to deliver sufficiently accurate exposures having maximum dosing errors of ≤5%. Comparable rates of 'dosimetric compliance' were noted between OSL- and TLD-based tests. Data analysis showed a highly linear relationship between 'measured' and 'target' doses, with errors falling largely between 0 and 20%. Outliers were most notable for OSL-based tests, while multiple tests by 'non-compliant' laboratories using orthovoltage X-rays contributed heavily to the wide variation in dosing errors.

CONCLUSIONS

For the dosimetrically non-compliant laboratories, the relatively high rates of dosing errors were problematic, potentially compromising the quality of ongoing radiobiological research. This dosimetry effort proved to be instructive in establishing rigorous reviews of basic dosimetry protocols ensuring that dosing errors were minimized.

[Status report of Hungarian radiotherapy based on treatment data, available infrastucture, and human resources]

The purpose of the study is to report the status of Hungarian radiotherapy (RT) based on the assessment of treatment data in years 2012 to 2014, available infrastructure, and RT staffing. Between December 2014 and January 2015, a RT questionnaire including 3 parts (1. treatment data; 2. infrastructure; 3. staffing) was sent out to all Hungarian RT centers (n=12). All RT centers responded to all questions of the survey. 1. Treatment data: In 2014, 33,162 patients were treated with RT: 31,678 (95.5%) with teletherapy, and 1484 (4.5%) with brachytherapy (BT). Between 2012 and 2014, the number of patients treated with radiotherapy increased with 6.6%, but the number of BT patients decreased by 11%. Forty-two percent of all patients were treated in the two centers of the capital: 9235 patients (28%) at the National Institute of Oncology (NIO), and 4812 (14%) at the Municipial Oncoradiology Center (MOC). Out of the patients treated on megavoltage RT units (n=22,239), only 901 (4%) were treated with intensity-modulated RT (IMRT), and 2018 (9%) with image-guided RT (IGRT). In 2014, 52% of all BT treatments were performed in Budapest: NIO - 539 patients (36%); MOC - 239 patients (16%); and BT was not available in 3 RT centers. Prostate I-125 seed implants and interstitial breast BT was utilized in one, prostate HDR BT in two, and head&neck implants in three centers. 2. Infrastructure: Including ongoing development projects funded by the European Union, by the end of year 2015, 39 megavoltage teletherapy units, and 12 HDR BT units will be in use in 13 available Hungarian RT centers. 3. Staffing: Actually, 92 radiation oncologists (RO), 29 RT residents, 61 medical physicists, and 229 radiation therapy technologists are working in 12 RT centers. There are 23 vacant positions (including 11 RO positions) available at the Hungarian RT centers. According to the professional minimal requirements and WHO guidelines, the implementation of 11 new linear accelerators, and 1 BT units are needed in Hungary. Further resources for the development and upgrade of RT infrastructure and capacity should be allocated to RT centers in Budapest. Brachytherapy and modern teletherapy (e.g. IMRT and IGRT) are underutilized in Hungary compared to other European countries. Implementation of continuous education and practical training programs in leading Hungarian and international RT centers are suggested in an effort to a wider implementation of modern RT techniques in Hungarian RT centers.

Medical effects and risks of exposure to ionising radiation

Effects and risk from exposure to ionising radiation depend upon the absorbed dose, dose rate, quality of radiation, specifics of the tissue irradiated and other factors such as the age of the individual. Effects may be apparent almost immediately or may take decades to be manifest. Cancer is the most important stochastic effect at absorbed doses of less than 1 Gy. The risk of cancer induction varies widely across different tissues; however, the risk of fatal radiation-induced cancer for a general population following chronic exposure is about 5% Sv(-1). Quantification of cancer risk at doses of less than 0.1 Gy remains problematic. Hereditary risks from irradiation that might result in effects to offspring of humans appear to be much lower and any such potential risks can only be estimated from animal models. At high doses (over 1 Gy) cell killing and modification causes deterministic effects such as skin burns, and bone marrow depression, in which case immunosuppression becomes a critical issue. Acute whole body penetrating gamma irradiation at doses in excess of 2 Gy results in varying degrees of acute radiation sickness and doses over 10 Gy are usually lethal as a result of combined organ injury.

Effects of total body irradiation on fatty acid and total lipid content of rats

We examined time-dependent changes in plasma lipids of rats given total body irradiation (TBI) with X-rays at 3 Gy. for consecutive periods. Animals were exposed to x ray radiations consecutively for 20 days at 5 day interval thereafter five animals were picked at random and sacrificed (5, 10, 15 and 20 days after beginning the exposure). The triacylglycerols and total cholesterol serum levels were significant differences between control and experimental groups after the first exposure (5 days), values for the triacylglcerols were significantly higher with the second (day 10) and third (day 15) radiation exposures but not with the fourth radiation exposures (day 20) (p<0.05). However, the serum cholesterol values were not found to be significant with the second and third exposures but with the fourth exposure (day 20) (p<0.05). The serum HDL-C concentrations were not significantly different between control and experimental groups at any time analyzed. But the LDL cholesterol was found to decrease on days 5 and 20 of the experimental period. Our results indicate that the applied long term exposure to x rays ionization radiations exposure may induce slight but statistically significant alterations in some serum lipids profile of rats, within the physiological range. The mechanisms for the effects of these ionizing radiations on serum lipid profile are not well understand yet, we suggest that the changes could be due to some non-specific stress reactions. The consequences of our observation are not known yet, but could point to some possible clinical intervention.

Radiation doses originating from diagnostic procedures during the treatment and follow-up of children and adolescents with malignant lymphoma

Children with malignant lymphoma undergo many diagnostic procedures that involve exposure to ionising radiation. In addition, many, but by no means all, undergo further exposure to ionising radiation during radiotherapy. While therapeutic radiation exposures are prescribed, the extent of radiation exposure arising from diagnostic procedures utilised in such children is largely unknown. We completed an audit of the radiation doses arising from diagnostic imaging procedures performed in a cohort of children with malignant lymphoma. The cumulative effective radiation dose associated with radiographic and radioisotopic procedures was derived for 81 children and adolescents with malignant lymphoma during their diagnosis, treatment and follow-up. Thirty-eight of the 42 patients (90%) with Hodgkin lymphoma were alive at study termination, with follow-up periods ranging from 1.9 to 11.7 years (median 5.3). Thirty-three of the 39 patients (85%) with non-Hodgkin lymphoma were alive at study termination with follow-up periods ranging from 2.4 to 12.3 years (median 7.5). The median effective dose was 518 mSv for patients with Hodgkin lymphoma and 309 mSv for those with non-Hodgkin lymphoma. The maximum effective dose was 1.7 Sv. The principal contributors to the effective dose were computed tomography (CT) and nuclear medicine imaging procedures using (67)Ga. Protocols for the management of children and adolescents with malignant lymphoma should be reviewed in order to reduce the radiation detriment without loss of essential diagnostic information.

[Risk factors of graft-versus-host disease in patients after allogeneic stem cell transplantation]

BACKGROUND

Graft-versus-host disease (GVHD) is the most common and most serious complication of allogeneic hematopoetic stem cell transplantation (HSCT). The aim of this study was to assess the incidence of GVHD after allogeneic HSCT depending on the diagnosis and risk factors.

MATERIAL AND METHODS

The study group comprised 78 patients aged 18 to 61 in whom allogeneic transplantation of hematopoietic stem cell in the Department and Clinic of Hematology, Oncology and Internal Diseases of Medical University in Warsaw (Poland) was performed.

RESULTS

Acute form of GVHD was significantly more often occurred after total body irradiation (TBI) for patients with TBI who did not (p < 0.05).

CONCLUSIONS

Risk factors for aGVHD were: age of the recipient, acute myeloid leukemia, myeloablative conditioning, TBI and unrelated donor.

Stereotactic body radiation therapy for head and neck tumor: disease control and morbidity outcomes

We evaluated the efficacy and safety of stereotactic body radiation therapy (SBRT) for patients with head and neck tumors. From April 2005 through April 2008, 34 patients with head and neck tumors were treated with CyberKnife SBRT. Twenty-one of them had prior radiotherapy. Treatment sites were orbit (n = 7), cervical lymph nodes (n = 6), nasopharynx (n = 5), oropharynx (n = 4) and others (n = 12). The prescribed dose ranged from 19.5 to 42 Gy (median, 30 Gy) in 3-8 fractions for consecutive days. The target volume ranged from 0.7 to 78.1 cm(3) (median, 11.6 cm(3)). The median follow-up was 16 months. Treatment was well tolerated without significant acute complications in any cases. Complete response rate and partial response rate were 32.4% and 38.6%, respectively. The overall survival rates were 70.6% and 58.3% at 12 and 24 months, respectively. The overall survival was better in patients without prior radiotherapy within the previous 24 months or in case of smaller target volume. Six patients suffered severe late complications. All these patients had prior radiotherapy, and 2 of them developed massive hemorrhage in the pharynx and both died of this complication 5 and 28 months, respectively, after SBRT. Our preliminary results suggest that SBRT is an effective treatment modality for head and neck tumors. However, re-irradiation has significant risk of severe and even fatal late complications in the form of necrosis and hemorrhage in re-irradiated areas.

Quantifying the survival benefit for allogeneic hematopoietic stem cell transplantation in relapsed acute myelogenous leukemia

Allogeneic hematopoietic stem cell transplantation (HSCT) is the recommended therapy for patients with relapsed acute myelogenous leukemia (AML), despite little evidence showing a survival benefit in patients who undergo HSCT versus chemotherapy alone. Because a prospective randomized trial addressing this issue is unlikely, we retrospectively reviewed all patients receiving initial salvage therapy for AML at M.D. Anderson Cancer Center between 1995 and 2004, focusing on patients undergoing HSCT or chemotherapy without HSCT as second salvage after first salvage failed to produce complete remission (CR) (group A) and patients in first salvage-induced CR (group B). Median survival was 5.1 months for HSCT (n=84) versus 2.3 months for chemotherapy (n = 200; P = .004) in group A and 11.7 months for HSCT (n = 46) versus 5.6 months for chemotherapy (n = 66; P < . 001) in group B. HSCT was associated with a survival benefit in each of 8 subgroups defined by age < or > or = 50, high-risk cytogenetics or not, and treatment in first salvage-induced CR or second salvage, and also in 5 of 6 subgroups defined by age < or > or = 50 years and duration of first CR (CR1) (primary refractory, CR1 < or = 36 weeks, CR1 > 36 weeks). Our data suggest that HSCT is preferable to chemotherapy alone in these patients with poor prognoses, with particular benefits noted in patients under age 50 years.

Low-dose whole-body irradiation induced radioadaptive response in C57BL/6 mice

Radioadaptive survival responses after relatively low doses of radiation were investigated in C57BL/6 mice. The 8-week-old mice received whole-body mid-lethal challenging irradiation (5.9 Gy) at various intervals after conditioning whole-body irradiation with 50-400 mGy. Thereafter, survival of the mice was observed for 30 days. The mice receiving 400 mGy at 6 h before the challenging dose had a lower survival rate than the control group, but it was not observed when the conditioning 400-mGy irradiation was given 24 h beforehand. The conditioning doses of 100 and 200 mGy did not influence the survival of mice after the challenging dose. The mice receiving 50 mGy at 1 day, 3 days or 1 week before the challenging dose had a higher survival rate than the control, although this adaptive response was not observed when 50 mGy was given 6 h, 12 h, 3.5 weeks, or 5 weeks beforehand. When 50 mGy was given 2 weeks before the challenging dose, the adaptive response was observed in an experiment in which the mice were caged in our laboratory at the age of 5 weeks, whereas it was not observed in another experiment in which the mice were caged at 3 weeks. This study confirmed the presence of radioadaptive survival responses at the dose of 50 mGy given relatively shortly before the challenging dose.

Influence of PET/CT-introduction on PET scanning frequency and indications. Results of a multicenter study

AIM

To evaluate the influence of the introduction of combined PET/CT scanners into clinical routine. This investigation addresses the quantitative changes between PET/CT and stand alone PET.

METHODS

The study included all examinations performed on stand alone PET- or PET/CT-scanners within 12 month prior to and after implementation of PET/CT. The final data analysis included five university hospitals and a total number of 15 497 exams. We distinguished exams on stand alone tomographs prior to and after installation of the combined device as well as PET/CT scans particularly with regard to disease entities. Various further parameters were investigated.

RESULTS

The overall number of PET scans (PET and PET/CT) rose by 146% while the number of scans performed on stand alone scanners declined by 22%. Only one site registered an increase in stand alone PET. The number of exams for staging in oncology increased by 196% while that of cardiac scans decreased by 35% and the number of scans in neurology rose by 47%. The use of scans for radiotherapy planning increased to 7% of all PET/CT studies. The increase of procedures for so-called classic PET oncology indications was moderate compared to the more common tumors. An even greater increase was observed in some rare entities.

CONCLUSIONS

The introduction of PET/CT led to more than a doubling of overall PET procedures with a main focus on oncology. Some of the observed changes in scanning frequency may be caused by a rising availability of new radiotracers and advancements of competing imaging methods. Nevertheless the evident increase in the use of PET/CT for the most common tumour types demonstrates its expanding role in cancer staging. The combination of molecular and morphologic imaging has not only found its place but is still gaining greater importance with new developments in technology and radiochemistry.

Long-Term Outcomes of Myeloablation and Autologous Transplantation of Relapsed Acute Myeloid Leukemia in Second Remission: A British Society of Blood and Marrow Transplantation Registry Study

Relapsed acute myeloid leukemia (AML) in adults has a poor prognosis if treated with chemotherapy alone. Case series have previously supported the role of myeloablation and autologous transplantation as a potentially curative treatment. This study aimed to use the large numbers and extended follow-up data in the British Society of Blood and Marrow Transplantation (BSBMT) registry database to establish long-term outcomes and relate these to biological and procedural factors. The BSBMT registry database was used to retrospectively identify 152 adult patients (age, 16-69 years) with AML in second remission treated with autologous transplantation in 1982-2003. Cytogenetic data were available for 68% of the patients; of these, at diagnosis, 42% had good risk features, 57% had standard risk features, and 1% had poor risk features. Conditioning regimens varied; autologous rescue was provided with bone marrow (BM) (71%), peripheral blood stem cells (PBSCs) (18%), or both (11%), which were harvested during first complete remission (CR1) and/or second CR (CR2). Median follow-up was 84 months (range, 2-200 months). At 10 years, actuarial overall survival (OS) was 32%, progression-free survival (PFS) was 28%, and relapse rate (RR) was 57%. The 100-day nonrelapse mortality (NRM) was 7%, rising to 11% at 1 year and to 14% at 10 years. OS was significantly related to M3 subtype (5-year OS, 66%; P = .005), patient age at diagnosis (P = .005) and transplantation (P = .026), and length of CR1, with greatest significance if the patient was dichotomized at CR1 duration of < 8 months or > or = 8 months (P = .0001). There was no difference in OS between regimens containing total body irradiation (TBI) and chemotherapy alone (P = .7). In relation to the nature of autologous graft material, there was improved OS (P = .025) and PFS (P = .009) with the use of cells harvested entirely in CR1 compared with cells harvested in CR2 or in both CR1 and CR2. Engraftment times were significantly shortened with the use of PBSCs alone or in combination with BM compared with BM alone (P = .0001), but there was no significant long-term impact on OS, PFS, RR, or NRM. This study provides long-term follow-up data in one of the largest series of patients with standard-risk and good-risk AML in CR2 treated with autologous transplantation and supports earlier observations that long-term survival is achievable in about 1/3 of patients overall and in about 2/3 of patients with M3 with a relatively low NRM. Outcomes are better in patients with CR1 > or = 8 months by use of grafts obtained entirely in CR1 and use of PBSCs. TBI conditioning did not confer an advantage. Randomized studies against unrelated donor transplantation are warranted.

Modeling lung cancer incidence in rats following exposure to radon progeny

Lung cancer incidence in Sprague-Dawley rats was simulated by a biologically based carcinogenesis model, which is formulated mathematically in terms of a stochastic state-vector model. Doses to the sensitive target cells in the bronchial epithelium of the rat lung were calculated by a stochastic dosimetry model, considering the distinct monopodial branching structure and the crossfire of alpha particles from alveolar tissue to bronchial epithelium. Bronchial and alveolar cellular doses could reasonably be approximated by lognormal distributions, with geometric standard deviations (GSD) between 7 and 10, depending on exposure conditions. Based on a dose-exposure conversion factor of 8.5 mGy WLM(-1) and a GSD of 8, lung cancer incidences were calculated for each cumulative exposure category in the rat inhalation study, consisting of different exposure rates and exposure times. The fair agreement between theoretical predictions and experimental data over the whole exposure range emphasises the necessity to incorporate the full cellular dose distributions rather than their mean values.

Myeloablative allogeneic hematopoietic stem cell transplantation for Philadelphia chromosome-positive acute lymphoblastic leukemia in adults: significant roles of total body irradiation and chronic graft-versus-host disease

Disease-free survival in Philadelphia chromosome-positive ALL (Ph + ALL) is very poor, and allogeneic hematopoietic stem cell transplantation (allo-HSCT) is currently considered the only procedure with curative potential. To identify factors affecting transplant outcome, we analyzed the data from 197 Ph + ALL patients aged 16 years or older who had undergone allo-HSCT. The 5-year survival rates were 34% for patients in first complete remission (CR), 21% for those in second or subsequent CR, and 9% for those with active disease (P < 0.0001). Multivariate analysis showed four pre-transplant factors as significantly associated with better survival: younger age, CR at the time of transplantation, conditioning with total body irradiation, and HLA-identical sibling donor (P < 0.0001, P < 0.0001, P = 0.0301, P = 0.0412, respectively). Severe acute GVHD increased the risk of treatment-related mortality (TRM) without diminishing the risk of relapse, whereas chronic GVHD reduced the risk of relapse without increasing the risk of TRM. Thus, patients who developed extensive chronic GVHD had better survivals (P = 0.0217), and those who developed grade III-IV acute GVHD had worse survivals (P = 0.0023) than did the others.

[Acute tolerance in hyperfractionated accelerated whole-body irradiation]

BACKGROUND

Acute side effects of total body irradiation lead to intense molestations of the patients. Therefore, it is desirable to take measures to reduce these side effects. In a retrospective study the frequency of acute side effects of a hyperfractionated accelerated total body irradiation was assessed and compared to frequencies of other exposure schedules published in the literature. Additionally the influence of ondansetron on the frequency of nausea and vomiting was investigated.

PATIENTS AND METHOD

From 1989 to 1992, 76 patients (47 male, 29 female; median age 38 years) underwent total body irradiation before autologous bone marrow transplantation. They received 3 daily doses of 1.20 Gy each every 4 h on 4 successive days to a total dose of 14.40 Gy. Thirty-nine patients received 3 x 8 mg (daily, intravenous or per os) ondansetron during the whole course of irradiation.

RESULTS

The most relevant side effects were nausea and vomiting. Patients, who did not receive ondansetron (n = 37) showed a nausea and emesis rate of 73%. With ondansetron (n = 39) nausea and emesis were reduced to 38%. Also the grade of severity of these side effects was reduced.

CONCLUSIONS

Ondansetron proved to be an effective medicament for relieving nausea and vomiting during total body irradiation. The results obtained are in concordance with those published in the literature.

Lung compensation in total body irradiation: a radiographic method

Using megavoltage radiography and a composite chest phantom, exit dose measurements were carried out to establish an empirical relationship between the optical film density and the corresponding equivalent thickness of overlying phantom material. Results for Co-60, 4-MV, and 10-MV photons show that the relationship depends on the sensitometric properties of the radiographic film and the photon beam quality. For an actual patient undergoing total body irradiation (TBI), a chest radiograph in treatment geometry provides the optical density information that is used to calculate the tissue deficit in the lung region. The compensators are made of lead whose thickness is chosen to replace the tissue deficit over the lung region. The validity of the method is established both by comparing its results to that obtained from multiple-slice computed tomography (CT) data for 4- and 10-MV photons, and by in-phantom thermoluminescent dosimetry (TLD) for Co-60, 4-MV and 10-MV beams.