The Influence of Aerosol Density and Shape Factor on the Assessment of Internal Exposure to 239Pu

Internal exposure due to inhalation of aerosols depends on the ratio of aerodynamic shape factor (χ) to aerosol mass density (ρ). Inhaled aerosol parameters may differ from the default ρ and χ values provided by the International Commission on Radiological Protection, which are adopted for the assessment of internal exposures. This paper focuses on the influences of χ/ρ on the assessment of internal exposure to Pu for reference workers. Regional deposition fractions are found to decrease with increasing χ/ρ, and larger decreases are observed with smaller activity median aerodynamic diameter aerosols, while the slow clearance fractions (fs) in the tracheobronchial region are more sensitive for larger activity median aerodynamic diameter aerosols. Results from biokinetics calculations reveal that both the time-dependent content (excretion) and cumulative activities are determined mainly for particles initially deposited in the alveolar-interstitial region, while fs affects the local cumulative activities in the tracheobronchial region. χ/ρ is proven to have different influences for aerosols with different activity median aerodynamic diameters. The default χ/ρ values can be used when activity median aerodynamic diameters are greater than 1 μm, while one should pay attention to the value of χ/ρ when activity median aerodynamic diameters are less than 1 μm, where significant influence may be anticipated.

Internal Dose Assessment after 131I-Iodide Misadministration in a Patient With Incompletely Blocked Thyroid Uptake: Personalized Internal Dose Assessment by Estimating Individual-Specific Biokinetics

In July 2017, a medical accident occurred in South Korea, in which I-iodide solution was misadministered to the wrong patient. Although the International Commission on Radiological Protection provided internal dose coefficients for iodine for blocked thyroid, they were not reliable enough for determining the dose to the patient (whose thyroid uptake was incompletely blocked) due to a discrepancy in biokinetics. Therefore, a personalized dose assessment was performed to derive the individual-specific dose coefficients for the patient. Initially, the thyroid biokinetics of the patient were statistically clarified by fitting bioassay monitoring results and the corresponding predicted bioassay values, which were calculated repeatedly for varying iodine transfer rates in an iodine biokinetic model. After determining the transfer rate for the patient, the individual-specific dose coefficients were then calculated in accordance with latest recommendations of the International Commission on Radiological Protection. According to the individual-specific biokinetics, the 24 h thyroid uptake fraction of iodine was estimated as 0.52%. The thyroid absorbed dose of the patient was evaluated as 21.2 Gy, which differed greatly (by about 9 Gy) from the dose evaluated simply using the reference data for blocked thyroid uptake. The personalized dose assessment carried out for the patient not only reduced considerable uncertainties in the internal dose calculation, but also improved the reliability of the calculated internal dose by adopting the latest dosimetric data, including specific absorbed fraction values based on voxel phantoms. Through the dose assessment of the patient, the methodology of personalized dose assessment considering individual-specific biokinetics was developed.

Proton therapy for hepatocellular carcinoma: Current knowledges and future perspectives

Hepatocellular carcinoma (HCC) is the second leading cause of cancer-related death, as few patients can be treated with currently available curative local modalities. In patients with HCC where curative modalities are not feasible, radiation therapy (RT) has emerged as an alternative or combination therapy. With the development of various technologies, RT has been increasingly used for the management of HCC. Among these advances, proton beam therapy (PBT) has several unique physical properties that give it a finite range in a distal direction, and thus no exit dose along the beam path. Therefore, PBT has dosimetric advantages compared with X-ray therapy for the treatment of HCC. Indeed, various reports in the literature have described the favorable clinical outcomes and improved safety of PBT for HCC patients compared with X-ray therapy. However, there are some technical issues regarding the use of PBT in HCC, including uncertainty of organ motion and inaccuracy during calculation of tissue density and beam range, all of which may reduce the robustness of a PBT treatment plan. In this review, we discuss the physical properties, current clinical data, technical issues, and future perspectives on PBT for the treatment of HCC.

[Towards an improvement of the quality of life after radiotherapy in children]

Pediatric radiotherapy did not differ technically from adult radiotherapy but its characteristics, its difficulties and challenges are specific. Thanks in part to this treatment, overall survival of French children with cancer is around 80%. It is therefore important to integrate in the elaboration of the treatment planning potential side long-term effects. Indeed, whatever the technique is, even the most sophisticated, it is usually inevitable that healthy nearby organs receive a dose of radiation. Dose limits on organs at risk come from adult data and are adapted for children. After the treatment, it is important to graduate the potential risks of side effects to propose a personalized monitoring protocol avoiding excessive medicalization. This article presents the medical thinking concerning radiotherapy in different anatomical areas (brain, head and neck, chest, abdomen) including concepts of dose level corresponding to side effects usually described. In parallel, we present follow-up recommendations with the aim to preserve an optimal quality of life for the adults cured of a childhood cancer, currently called survivors.

An internal radiation dosimetry computer program, IDAC 2.0, for estimation of patient doses from radiopharmaceuticals

The internal dosimetry computer program internal dose assessment by computer (IDAC) for calculations of absorbed doses to organs and tissues as well as effective doses to patients from examinations with radiopharmaceuticals has been developed. The new version, IDAC2.0, incorporates the International Commission on Radiation Protection (ICRP)/ICRU computational adult male and female voxel phantoms and decay data from the ICRP publication 107. Instead of only 25 source and target regions, calculation can now be made with 63 source regions to 73 target regions. The major advantage of having the new phantom is that the calculations of the effective doses can be made with the latest tissue weighting factors of ICRP publication 103. IDAC2.0 uses the ICRP human alimentary tract (HAT) model for orally administrated activity and for excretion through the gastrointestinal tract and effective doses have been recalculated for radiopharmaceuticals that are orally administered. The results of the program are consistent with published data using the same specific absorption fractions and also compared with published data from the same computational phantoms but with segmentation of organs leading to another set of specific absorption fractions. The effective dose is recalculated for all the 34 radiopharmaceuticals that are administered orally and has been published by the ICRP. Using the new HAT model, new tissue weighting factors and the new adult computational voxel phantoms lead to an average effective dose of half of its earlier estimated value. The reduction mainly depends on electron transport simulations to walled organs and the transition from the stylised phantom with unrealistic interorgan distances to more realistic voxel phantoms.

Identification of motor neurons and a mechanosensitive sensory neuron in the defecation circuitry of Drosophila larvae

Defecation allows the body to eliminate waste, an essential step in food processing for animal survival. In contrast to the extensive studies of feeding, its obligate counterpart, defecation, has received much less attention until recently. In this study, we report our characterizations of the defecation behavior of Drosophila larvae and its neural basis. Drosophila larvae display defecation cycles of stereotypic frequency, involving sequential contraction of hindgut and anal sphincter. The defecation behavior requires two groups of motor neurons that innervate hindgut and anal sphincter, respectively, and can excite gut muscles directly. These two groups of motor neurons fire sequentially with the same periodicity as the defecation behavior, as revealed by in vivo Ca(2+) imaging. Moreover, we identified a single mechanosensitive sensory neuron that innervates the anal slit and senses the opening of the intestine terminus. This anus sensory neuron relies on the TRP channel NOMPC but not on INACTIVE, NANCHUNG, or PIEZO for mechanotransduction.

Assessing the reliability of dose coefficients for ingestion and inhalation of 226Ra and 90Sr by members of the public

Assessments of risk to a population group resulting from internal exposure to a particular radionuclide can be used to assess the reliability of the appropriate International Commission on Radiological Protection (ICRP) dose coefficient, E(50), used as a radiation protection device for the specified exposure pathway. An estimate of the uncertainty on the risk is important for informing judgements on reliability. This paper describes the application of parameter uncertainty analysis to quantify uncertainties resulting from internal exposures to radioisotopes of the alkaline earth metals, (90)Sr and (226)Ra, by members of the UK public. The study derives uncertainties in biokinetic model parameter values to calculate the distributions of the effective dose per unit intake using the ICRP Publication 60 formalism. The distributions are used to infer the uncertainty on the mean effective dose per unit intake to inform the derivation of uncertainty factors (UF) for the appropriate ICRP Publication 72 dose coefficients. Here, a UF indicates a 95 % probability that the best estimate of risk per unit intake is within a factor, UF, of the nominal risk associated with the appropriate ICRP dose coefficient, E(50), with respect to uncertainties in the biokinetic model parameter values. Ingestion: it is assumed that exposure occurs through the ingestion of radionuclides present in food and water. The results for both radionuclides suggest a UF of within 3 for all age groups, with median values close to the ICRP values. Inhalation: it is assumed that environmental exposure to radium occurs primarily due to insoluble forms present in fly ash discharged from coal-fired power stations; for strontium, exposure is assumed to occur due to residual aerosols produced as a result of atmospheric nuclear testing and nuclear reactor accidents. The results suggest a UF of around 3 and 6 for inhalation of (90)Sr and (226)Ra, respectively, by members of the public.

[Five-year results of IMRT for prostate cancer - toxicity]

BACKGROUND

Intensity modulated radiotherapy (IMRT) plays a crucial role in the treatment of prostate cancer thanks to its capacity for healthy tissue sparing. This work reports on the acute and late toxicity rates among 233 patients treated with high-dose IMRT.

MATERIAL AND METHODS

From June 2003 to December 2007, 233 men with clinically localized prostate cancer underwent radical radiotherapy. One hundred sixty patients were treated with IMRT to the prostate and the base of seminal vesicles to 78 Gy in 39 fractions, 73 patients underwent simultaneous integrated boost. Prescribed doses were 82 Gy and 73,8 Gy in 41 fractions to the prostate and seminal vesicles, respectively. Late toxicity was evaluated prospectively using a RTOG/FC-LENT score.

RESULTS

Thirty patients (12.8%) experienced acute Grade 2 gastrointestinal (GI) toxicity. No acute Grade 3 or 4 GI toxicity developed. Forty two patients (18.1%) experienced acute Grade 2 genitourinary toxicity and 23 patients (9.9%) had Grade 3 GU toxicity. Grade 4 Genitourinary toxicity was observed in nine (3.8%) patients, due to a need of short-term urinary catheterization. With a median follow-up of 49.2 months, the estimated 5-year cumulative incidence of Grade 2 gastrointestinal toxicity was 22.4%. The estimated 5-year cumulative incidence of Grade 2 genitourinary toxicity was 17.7%.

CONCLUSION

Intensity modulated radiotherapy enables dose escalation to 78-82 Gy with an acceptable toxicity.

Biokinetic analysis code development and applications to visualise the distribution of intake activity

Measurements for internal dose assessment are required to be conducted based on the distribution of radionuclides in the body, which may change depending on the lapsed time. In this study, a biokinetic analysis code, which can be used in practical radiation control is developed, and the results of (60)Co and (137)Cs biokinetics are visualised as examples by drawing the depositions for each organ and tissue in a figure of the body as a function of lapsed time. In addition, based on visualised biokinetics, precautions for in vivo measurements are also discussed. These discussions led to the conclusion that the information of visualised biokinetics is useful for actual measurements in practical radiation control.

Suspended C60 nanoparticles protect against short-term UV and fluoranthene photo-induced toxicity, but cause long-term cellular damage in Daphnia magna

The increased production of nanotechnology materials is a potential source of nano-sized particles (NSPs) in aquatic ecosystems. Meanwhile, polycyclic aromatic hydrocarbons (PAHs), in the presence of ecologically relevant levels of ultraviolet radiation (UV), can be acutely toxic to aquatic species including fish and invertebrates. Considering that suspended carbon-based NSPs (e.g., C60 fullerenes) may act in similar ways as dissolved organic matter (DOM) by altering the bioavailability of PAHs, the objective of this research was to determine the effect of suspended C60 on the photo-induced toxicity of fluoranthene. Transmission electron microscopy indicated that the presence of C60 protected cellular components (e.g., mitochondria, microvilli, and basal infoldings) in organisms exposed to UV and fluoranthene phototoxicity in short-term exposures. However, we found that long-term exposure (21d) of low-level C60 caused significant cellular damage in the Daphnia magna alimentary canal. This paper highlights the importance of examining the interactions between existing stressors and nanoparticles in the aquatic environment.

A novel animal model to investigate fractionated radiotherapy-induced alimentary mucositis: the role of apoptosis, p53, nuclear factor-kappaB, COX-1, and COX-2

Radiation-induced mucositis is a common and serious side effect of radiotherapy. Molecular mechanisms of mucosal injury, however, are still poorly understood and extremely difficult to study in humans. A novel Dark Agouti rat model using fractionated radiotherapy to induce mucositis has been developed to investigate the occurrence of alimentary mucosal injury. Twenty-four Dark Agouti rats were randomly assigned to receive either fractionated radiotherapy or no radiotherapy. The irradiated rats received a fractionated course of abdominal radiotherapy at 45 Gy/18 fractions/6 weeks treating thrice weekly (i.e., at a radiation dose of 2.5 Gy per fraction). After each week of radiation, a group of irradiated rats was killed. Histomorphology and mucin distribution in the alimentary tract was investigated. The terminal deoxynucleotidyl transferase-mediated dUTP nick end labeling assay was used to examine apoptosis in the colon and jejunum, and intestinal morphometry was used to assess villus length, crypt length, and mitotic crypt count. Immunohistochemistry of p53, nuclear factor-kappaB, cyclooxygenase (COX)-1, and COX-2 was also done. The fractionated radiotherapy course induced alimentary mucositis from week 1, with more severe injury seen in the small intestine. The hallmark appearance of apoptosis was present in the crypts of the small and large intestine. In the jejunum and colon, goblet cell disorganization and degeneration was obvious and crypt mitotic counts were severely depleted throughout the treatment. Expression of p53, nuclear factor-kappaB, COX-1, and COX-2 was increased in the irradiated intestinal sections. Fractionated radiation-induced alimentary mucositis has been effectively documented in the Dark Agouti rat for the first time. Further studies investigating the molecular mechanisms underlying radiation-induced mucositis are planned to ultimately achieve anti-mucotoxic-targeted therapies.

Effects of gamma-irradiation on midgut proteolytic activity of the mediterranean fruit fly, Ceratitis capitata (Diptera: Tephritidae)

The Mediterranean fruit fly (medfly), Ceratitis capitata (Wiedemann), is a key pest of citrus in Spain because of significant yield losses and to quarantine restrictions. Biologically based control methods, such as the Sterile Insect Technique (SIT), which relies on the sterilization by irradiation of large numbers of insects, is gaining an increasing role in the control of medfly in Mediterranean areas. However, gamma-irradiation might damage the midgut epithelium cells, causing a lowering of nutritive assimilation that can negatively affect adult performance. Irradiation effects on digestive physiology are well established for a number of insect pests, but there is no information on medfly. Our aim was to determine the effects of gamma-irradiation on C. capitata digestive protease activity. Both larvae and adults were found to use a similar proteolytic system based on aspartyl-, trypsin-, chymotrypsin-, amino peptidase-, and carboxypeptidase A- and B-like activities. Pupae of the Vienna-7 (tsl) strain were irradiated at 70 or 140 Gy, two days before emergence, and the adults fed during 5 days on sugar-protein (4:1) diets. Protease activity was measured in midgut extracts and compared with males non-irradiated reared in the same conditions. The results showed that the irradiation doses tested had no effect on the digestive proteolytic activities of medfly adults. Moreover, the longevity of irradiated medflies at the highest dose (140 Gy) was similar to that of controls.

The atlas of complication incidence: a proposal for a new standard for reporting the results of radiotherapy protocols

We present a new method of reporting the results of radiotherapy protocols. The dose-volume atlas of complication incidence is a comprehensive and unbiased summary of the dose-volume exposures and complications occurring in patients after treatment. This new tool provides clear and systematic information about the safety of regions of dose-volume exposure previously treated that can be used when considering new treatments. Actuarial and model-dependent versions of the atlas are described. By using the raw data in the appropriate forms of the atlas, logistic regression, Kaplan-Meier, and Cox proportional hazards analysis can be performed, allowing for the independent calculation of dose-volume response. The data required are simple enough that provided compatible definitions of dose, volume, and complications are used, atlases from different protocols are potentially additive, facilitating the meta-analysis of inter-interinstitutional data. If this method were adopted as a standard for reporting the outcome of treatment protocols, a potentially synergistic increase in the utility of each protocol could result.

Alimentary hyperlipemia of rabbits is affected by exposure to low-intensity pulsed magnetic fields

An experimental study was carried out in rabbits to investigate the effects of exposing rabbits to low-intensity pulsed magnetic fields (PMFs) on alimentary hyperlipemia. Thirty female white big ear rabbits were randomly divided into three groups. The normal group was fed with a standard chow diet and the other two groups (hyperlipid and magnetic) were fed with the chow diet supplemented with cholesterol, yolk powder and lard. The magnetic group was exposed to 15 Hz pulsed magnetic fields. After 8 weeks, levels of blood lipid and indices of hemorheology were examined. In addition, histomorphologic changes of hepatic and myocardial tissues were compared across the groups respectively. Compared with the hyperlipid group, hemorheology indices of the magnetic group reduced significantly from 12.80% to 38.05% (P < 0.01) indicating lower blood viscosity. Similarly, compared with the hyperlipid group, the levels of total cholesterol and triglycerides in the magnetic group decreased 40.52% and 52.42% (P < 0.01). On the contrary, high density lipoprotein (HDL) value obviously increased 66.67% (P < 0.01). Furthermore, compared with the control group, the values of triglycerides and HDL of the magnetic group did not show statistical differences (P > 0.05). The deposit of fatty material on the inner lining of thoracic aorta wall of the magnetic group was significantly lighter than that of the hyperlipid group. Numerous aggregation of lipoids emerged among myocardial myofibrils in the hyperlipid group, while no notable change was found in both the magnetic and control group. The results indicate that low-intensity PMFs could be helpful for the treatment of alimentary hyperlipemia.

Doses from radon and its decay products to children

This paper considers doses from radon and decay products when inhaled or ingested by one year old infants and by ten year old children. Doses from decay products deposited on skin are also discussed. For inhalation and ingestion, the general pattern of doses to organs is broadly similar to that in adults. Much the largest doses are received by the organ of intake (respiratory tract and stomach respectively). Otherwise, tissues with higher fat content tend to receive somewhat higher doses from radon gas than other tissues. Dose coefficients (dose per unit intake factors) for children are generally larger than those for adults. However, total annual doses are more similar across the age groups because of smaller intakes of air and water by children. Radon decay products deposited on skin may be able to induce skin cancer. However, the location of the sensitive cells is not known with certainty and they may lie too deep to receive significant dose. If they are irradiated, it is likely that doses to children would be larger than for adults. The radiological significance of doses to children is discussed.

Loss of interstitial cells of Cajal after pulsating electromagnetic field (PEMF) in gastrointestinal tract of the rats

Exposure to the magnetic field has remarkably increased lately due to fast urbanization and widely available magnetic field in diagnosis and treatment. However, biological effects of the magnetic field are not well recognized. The myoelectric activity recorded from the gastrointestinal and urinary systems is generated by specialized electrically active cells called interstitial cells of Cajal (ICCs). Thus it seems rational that ICC have significant vulnerability to physical factors like an electromagnetic field. The aim of this study was to evaluate the influence of pulsating electromagnetic field (PEMF) (frequency 10 kHz, 30ms, 300 muT burst, with frequency 1Hz) on ICCs density in the rat gastrointestinal tract. Rats were divided into two groups (n=32). The first group was exposed to PEMF continuously for 1, 2, 3, and 4 weeks (n = 16), and the second group (n=16) served as a control. Tissue samples of the rat stomach, duodenum and proximal colon were fixed and paraffin embedded. The tangential sections of 5 microm thickness were stained immunohistochemically with anti-c-Kit (sc-168) antibody and visualized finally by DAB as chromogen (brown end product). C-Kit positive branched ICC-like cells were detected under the light microscope, distinguished from the c-kit-negative non-branched smooth muscle cells and from the c-kit positive but non-branched mast cells and quantitatively analyzed by MultiScan computer program. Apoptosis detection was performed with rabbit anti-Bax polyclonal antibody (Calbiochem, Germany) and LSAB 2 visualization system. The surface of c-Kit immunopositive cells decreased after exposure to PEMF in each part of the gastrointestinal tract. Reduced density of ICCs was related to exposure time. The most sensitive to PEMF were ICCs in the fundus of the stomach and in the duodenum, less sensitive were ICCs in the colon and pacemaker areas of the stomach. No marked changes in ICC density in the pyloric part of the stomach were observed. We demonstrate that the PEMF induced apoptosis dependent decrease in ICC expression.

Can Intensity-Modulated Radiation Therapy of the Paraaortic Region Overcome the Problems of Critical Organ Tolerance?

BACKGROUND AND PURPOSE

The recent RTOG guidelines for future clinical developments in gynecologic malignancies included the investigation of dose escalation in the paraaortic (PO) region which is, however, very difficult to target due to the presence of critical organs such as kidneys, liver, spinal cord, and digestive structures. The aim of this study was to investigate intensity-modulated radiotherapy's (IMRT) possibilites of either increasing, in a safe way, the dose to 50-60 Gy in case of macroscopic disease or decreasing the dose to organs at risk (OR) when treatment is given in an adjuvant setting.

MATERIAL AND METHODS

The dosimetric charts of 14 patients irradiated to the PO region at the Department of Radiation Oncology, University Hospital of Liege, Belgium, in 2000 were analyzed in order to compare six-field conformal external-beam radiotherapy (CEBR) and five-beam IMRT approaches. Both CEBR and IMRT investigations were planned to theoretically deliver 60 Gy to the PO region in the safest way possible. Dose-volume histograms (DVHs) were calculated for clinical target volume (CTV), planning target volume (PTV), and OR. Student's t-test was used to compare the paired DVH data issued from CEBR and IMRT planning.

RESULTS

The IMRT approach allowed to cover the PTV at a higher level as compared to CEBR. Using IMRT, the maximal dose to the spinal cord was reduced from 42.5 Gy to 26.2 Gy in comparison with CEBR (p < 0.00001). Doses to the kidneys were significantly reduced, with < 20% receiving >or= 20 Gy in the IMRT approach (p < 0.00001). Irradiation of digestive structures was not different, with < 25% receiving 35 Gy. Doses to the liver remained low regardless of the method used.

CONCLUSION

At 60 Gy, IMRT is largely sparing the spinal cord and kidneys as compared to CEBR and represents an interesting approach not only for dose escalation up to 50-60 Gy (probably facilitating the radiochemotherapy approaches) but also in an adjuvant setting at lower doses. The dosimetric data of this study are in the same range as those published recently with a dynamic arc conformal approach.

Analysis of acute toxicity with use of transabdominal ultrasonography for prostate positioning during intensity-modulated radiotherapy

OBJECTIVES

To analyze the effects of the B-mode ultrasound acquisition and targeting (BAT) system for positioning of patients with prostate cancer receiving intensity-modulated radiotherapy on acute gastrointestinal (GI) and genitourinary (GU) toxicity.

METHODS

The records of 50 consecutive patients treated using the BAT system were reviewed. Additionally, a comparison (no-BAT) group (ie, a group without a BAT study) treated in a similar manner was identified. The no-BAT group consisted of 49 patients treated immediately before the BAT group. For the two groups, the target definitions and dose prescriptions were identical, the treatment plan acceptance criteria were identical, and intensity-modulated radiotherapy was used for all patients. The daily BAT movements were charted in each of the three principal directions. Acute toxicity was scored for all patients according to the Radiation Therapy Oncology Group GI and GU acute toxicity scales.

RESULTS

The GU toxicity rates for the BAT versus no-BAT groups were grade 0 in 20% versus 14%; grade 1 in 38% versus 47%; grade 2 in 38% versus 39%; and grade 3 in 4% versus 0%, respectively (P = 0.284). The corresponding GI toxicity rates were grade 0 in 42% versus 27%; grade 1 in 28% versus 29%; and grade 2 in 30% versus 45% (P = 0.040). The incidence of GU and GI toxicity did not correlate with the directions or size of the BAT moves. Regression analysis revealed that for acute GI toxicity, the only variable reaching statistical significance was BAT use; no variable, including BAT use, reached statistical significance for acute GU toxicity.

CONCLUSIONS

The use of the BAT system did not change the rate of acute GU toxicity but did reduce the rate of acute GI toxicity.

[Locoregional recurrent rectal cancer: the place of radiotherapy]

Currently, locoregional recurrence of rectal cancer is rare due to the therapeutic progress of total mesorectal excision and pre-operative radiotherapy. Nevertheless, a curative treatment could be proposed provided that surgical removal is possible and complete. Here, we will discuss the position of both external and intra-operative radiotherapy, and concomitant chemotherapy. Actually, multimodal therapy provides the best results for local control and overall survival. Exclusive external radiotherapy is indicated for palliative treatment of unresectable cases of recurrence.

[Radiotherapy in combination with low-dose chemotherapy in locally advanced head and neck cancer]

A previous preclinical study revealed that the maximal additive effect between chemotherapy (CT) and irradiation (RT) occurred at a low level of CT. Therapy was therefore designed with an oral drug daily given in combination with RT in order to determine the efficacy and toxicity. Locoregionally advanced head and neck tumor patients were treated with simultaneous RT and CT. RT was administered 5 times per week at 2 Gy per fraction in a total dose of 70 Gy. Throughout the treatment 30 mg/kg Tegafur was given daily orally. In the period between 2000 and 2002, 50 patients were enrolled. Complete remission was attained in 60%, with an overall response rate of 94%. Acute mucositis of grade 2 or 3 was observed in 56% (28 patients), and gastrointestinal and hematologic toxicity of grade 2 or 3 occurred in 8% (4 patients). Because of side-effects, the duration of treatment was at most 2 weeks longer. Toxicity was eliminated quickly by careful supportive therapy. In conclusion, it is considered that oral low-dose CT in combination with RT is an efficient and simple mode of treatment for locally advanced head and neck tumor patients with a poor prognosis.

Dual effect of p53 on radiation sensitivity in vivo: p53 promotes hematopoietic injury, but protects from gastro-intestinal syndrome in mice

Ionizing radiation (IR) induces p53-dependent apoptosis in radiosensitive tissues, suggesting that p53 is a determinant of radiation syndromes. In fact, p53-deficient mice survive doses of IR that cause lethal hematopoietic syndrome in wild-type animals. Surprisingly, p53 deficiency results in sensitization of mice to higher doses of IR, causing lethal gastro-intestinal (GI) syndrome. While cells in the crypts of p53-wild-type epithelium undergo prolonged growth arrest after irradiation, continuous cell proliferation ongoing in p53-deficient epithelium correlates with accelerated death of damaged cells followed by rapid destruction of villi and accelerated lethality. p21-deficient mice are also characterized by increased sensitivity to GI syndrome-inducing doses of IR. We conclude that p53/p21-mediated growth arrest plays a protective role in the epithelium of small intestine after severe doses of IR. Pharmacological inhibition of p53 by a small molecule that can rescue from lethal hematopoietic syndrome has no effect on the lethality from gastro-intestinal syndrome, presumably because of a temporary and reversible nature of its action.

[Pilot study of conformal intensity modulated radiation therapy for localized prostate cancer]

PURPOSE

- To report our experience on treatment planning and acute toxicity in 16 patients suffering from clinically localized prostate cancer treated with high-dose intensity-modulated radiation therapy (IMRT).

PATIENTS AND METHODS

- Between March 2001 and October 2002, 16 patients with clinically localized prostate cancer were treated with IMRT. Treatment planning included an inverse-planning approach, and the desired beam intensity profiles were delivered by dynamic multileaf collimation. All patients received the entire treatment course with IMRT to a prescribed dose of 78 Gy. All IMRT treatment plans were compared with a theoretical conventional three-dimensional conformal radiation therapy (3D-CRT). Acute lower gastro-intestinal (GI) and genito-urinary (GU) toxicity was evaluated in all patients and graded according to the Common Toxicity Criteria for Adverse Events version 3.0 (CTCAE v. 3.0). A relationship between dose volume and clinical toxicity was evaluated.

RESULTS

- Ninety-five percent of the PTV2 received more than 76 Gy using IMRT or 3D-CRT with no difference between both methods. The dose-volume histogram mean obtained for the PTV2 was not different between IMRT and 3D-CRT. IMRT improved homogeneity of the delivered dose to the PTV2 as compared with 3D-CRT (7.5 vs 9%, respectively). Ninety-five percent of the PTV1 received 5 Gy more using IMRT with protection of the bladder and the rectum walls. The benefit was considered below 75 and 70 Gy for the wall of the bladder and the rectum, respectively. Grade 2 GI and GU toxicity was observed in four (25%) and five (31%) patients, respectively. No grade 3 toxicity was observed. There was a trend towards a relationship between the mean rectal dose and acute rectal toxicity but without statistical significant difference (P =0.09).

CONCLUSION

- Dose escalation with IMRT is feasible with no grade 3 or higher acute GI or GU toxicity. Examination of a larger cohort and longer-term follow-up are warranted in the future.

[Brachytherapy boost irradiation in the treatment of high risk, localised prostate cancer. Initial national experience in Hungary]

PURPOSE

To describe the technique and early results of ultrasound (US)-guided interstitial prostate brachytherapy (BT) introduced at our institute.

MATERIALS AND METHODS

Between December 2001 and July 2002, ten patients with clinically localised, high risk prostate cancer were treated with external beam irradiation and high dose rate (HDR) BT boost at the Radiotherapy Department of National Institute of Oncology, Budapest. Using CT based treatment planning, 46 Gy was delivered to the whole pelvis and then the prostate and vesicles were treated up to a total dose of 60 Gy by conformal external beams. BT boost was given in the first four weeks of external irradiation. Nine patients were under total androgen blockade. The interstitial BT was performed in spinal anaesthesia. Steel needles were implanted into the prostate using transrectal US guidance. The Ir-192 HDR isotope was loaded into the needles by remote control after-loading equipment. Treatment planning was based on transversal ultrasound images. The target volume was the whole prostate. The median number of inserted needles was 9 (range: 5-13). The prescribed dose to the surface of the prostate was 8 or 10 Gy, and the maximum reference dose of the urethra or rectum was less than 125% and 80% of the prescribed dose, respectively. PSA (prostate specific antigen) levels and acute side effects were monitored and documented regularly.

RESULTS

The prescribed treatment was completed on all patients. The median follow-up time from the completion of the radiotherapy was 6 months (range: 2-11 months). Perioperative side effects (haematuria caused by puncture of the bladder) occurred in two cases. Acute grade 2 toxicity was observed in four patients: genitourinal inflammation in 4, and proctitis in 2 cases. No PSA relapse occurred so far.

CONCLUSION

In our study we described our technique of interstitial BT boost as a part of prostate radiotherapy used for the first time in Hungary. The US based treatment planning resulted in adequate dose distribution in all cases. Incidence of perioperative and acute side effects were comparable to data known from the literature. Appropriate technical background and well organised team work are needed to ensure the good quality of the treatment.

Development of software for internal dose calculation from bioassay measurements

Recently developed biokinetic models of ICRP permit increasingly realistic descriptions of the behaviour of radionuclides in the human body. This, however, has made the interpretation of bioassay data extremely difficult. Thus computer programs for implementing these models are in need, but very few are available. The present work describes personal-computer-based software, MONDAL2 (monitoring to dose calculation ver. 2), that enables users to estimate intake activity and the resulting effective doses from bioassay measurements for both workers and members of the public. This software runs on Microsoft Windows 95, 98, Millennium edition, 2000 or XP. If the system is to be fully copied to a hard disk, hard disk space of 23 MB is required. This software is distributed by the National Institute of Radiological Sciences free of charge.

Acute and long-term toxicity following radiotherapy alone or in combination with chemotherapy for locally advanced cervical cancer

Randomised studies in locally advanced cervical cancer patients showed that cisplatin should be given concurrently with radiotherapy, because of a better long-term survival compared to radiotherapy alone. This increases the relevance of treatment related toxicity. This review summarises the acute and long-term toxicity of radiotherapy given with or without chemotherapy for cervical cancer. Acute toxicity (all grades) of radiotherapy is reported in 61% of the patients in the rectosigmoid, in 27% as urological, in 27% as skin and in 20% as gynaecological toxicity. Moderate and severe morbidity consists of 5% to 7% gastrointestinal and 1% to 4% genitourinary toxicity. Adding chemotherapy to radiotherapy increases acute haematological toxicity to 5% to 37% of the patients and nausea and vomiting in 12% to 14%. Late effects of radiotherapy include gastrointestinal, urological, female reproductive tract, skeletal and vascular toxicity, secondary malignancies and quality of life issues. For at least 20 years after treatment, new side effects may develop. Gastrointestinal toxicity usually occurs in the first 2 years after treatment in about 10% of the patients. The incidence of moderate and severe urological toxicity can increase up to 10% and rises over time. Gynaecological toxicity usually occurs shortly after treatment while skeletal and vascular toxicity can occur years to decades later. Thus far, no increase in late toxicity has been observed after the addition of cisplatin to radiotherapy. Finally, methods to prevent or decrease late toxicity and therapeutical options are discussed. However, most randomised studies still have a limited follow-up period.

Normal tissue tolerance to intraoperative radiotherapy

Much experimental evidence has been accumulated assessing the tolerance of various tissues to IORT, and much of the tolerance data have resulted from the use of canine models. Guidelines of IORT tissue tolerance established in experimental models have been used in the clinical application of IORT at numerous institutions. Although the radiotolerance of differing tissues can vary among species, sufficient clinical experience has accumulated to validate the canine tissue tolerance model as representative of human tissue responses to IORT. Cellular effects from radiation principally stem from direct damage to DNA, and thus proliferating tissues are among the most radiosensitive, with arrested or abnormal cell division. These tissues can manifest striking early toxicity, reflecting the rate of cell division that is affected by the radiation. Irradiation of nonproliferating or slowly proliferating tissues may show little or no early toxicity, but late effects can be manifested to considerable and varying degrees. In much of this late toxicity, pathologic changes develop from progressive ischemia, brought about by the gradual obliteration of small blood vessels. Irradiated endothelium often becomes replaced by a thickened fibrous layer, which, in small vessels, leads to occlusion and ischemic necrotic changes in the supplied tissue. In larger vessels, fibrosis can lead to wall weakening and aneurysmal dilatation, rupture, or thrombosis. The common denominator, then, of radiation damage to many tissues is related to vascular effects. Although the tolerance to IORT-induced toxicity can vary considerably among tissues, doses ranging to 25 Gy can generally be tolerated without significant toxicity. Vital areas where IORT dose must be carefully monitored include critical vasculature, gastrointestinal viscera, ureter, significant motor or sensory nerve trunks, and central nervous system structures. Higher doses can generally be delivered safely to anatomic areas at risk for tumor that are at a distance from sensitive organs or tissues. The general principle providing the rationale of IORT should always be practiced: maximize the radiation dose to the tumor and tumor-harboring tissues while minimizing dose exposure to surrounding normal tissues.

Preliminary analysis of chronic gastrointestinal toxicity in gynecology patients treated with intensity-modulated whole pelvic radiation therapy

PURPOSE

To provide a preliminary analysis of chronic gastrointestinal (GI) toxicity in gynecology patients treated with intensity-modulated whole pelvic radiation therapy (IM-WPRT).

METHODS AND MATERIALS

Between February 2000 and August 2001, 36 gynecology patients received IM-WPRT. All patients underwent a contrast-enhanced computed tomography scan, and a clinical target volume (CTV) was contoured consisting of the upper vagina, parametria, uterus (if present), and presacral and pelvic lymph node regions. The CTV was expanded by 1 cm to create a planning target volume (PTV). Seven or 9-field IM-WPRT plans were generated. IM-WPRT plans were highly conformal, providing excellent coverage of the PTV and considerable sparing of normal tissues, including the small bowel and rectum. Chronic GI toxicity was scored: 0 (no symptoms), 1 (mild symptoms, no medications required), 2 (moderate symptoms, medications required), and 3 (severe symptoms, hospitalization, surgery required). Chronic GI toxicity in 30 gynecology patients treated with conventional WPRT patients before the implementation of IM-WPRT was also evaluated. Median follow-up in the IM-WPRT and WPRT groups were 19.6 and 30.2 months, respectively.

RESULTS

The IM-WPRT and WPRT groups were well balanced in terms of most patient and treatment factors, including age, site, stage, chemotherapy, WPRT dose, and brachytherapy, except for a higher frequency of surgery (75 vs. 54%, p = 0.02) in the IM-WPRT group. Overall, IM-WPRT patients had a lower rate of chronic GI toxicity (11.1 vs. 50.0%, p = 0.001) than WPRT patients. The percentage of IM-WPRT patients with Grade 1, 2, and 3 toxicity were 8.3%, 2.8%, and 0%, respectively. Corresponding percentages in the WPRT group were 30.0%, 16.7%, and 3.3%, respectively. The only other factor correlated with chronic GI toxicity was age (p = 0.02). On multivariate (logistic regression) analysis controlling for age and other clinical factors, IM-WPRT retained its statistical significance (p = 0.01; odds ratio 0.16; 95% confidence interval 0.04, 0.67)

CONCLUSIONS

Our results suggest that IM-WPRT is associated with less chronic GI toxicity than conventional WPRT in patients with gynecologic malignancies. However, longer follow-up and more patients are clearly needed to ascertain whether the benefits of IM-WPRT treatment seen here translate into true long-term reductions in chronic GI toxicity.

Salvage radiotherapy for biochemical failure of radical prostatectomy: a single-institution experience

OBJECTIVES

To review the efficacy of salvage radiotherapy (RT), to treat elevated prostate-specific antigen (PSA) levels for presumed local recurrence of prostatic adenocarcinoma after retropubic prostatectomy, and identify the factors that may predict for successful treatment.

METHODS

Fifty-one patients with hormonally naive pT2-3N0-1M0 prostate cancer were treated with RT for locally persistent or recurrent disease. The patients received a median dose of 65.7 Gy (range 61.2 to 72.3) to the prostate bed. Successfully treated patients had undetectable PSA levels; the endpoint of the study was biochemical failure.

RESULTS

The median follow-up was 3.8 years; 42 of 51 patients had at least 2 years of follow-up. Twenty-three patients (45%) were biochemically free of disease. The estimated biochemically free of disease rate at 3 and 5 years was 56% and 16%, respectively. Whether the patients were treated for persistently elevated PSA levels or for rising PSA levels from undetectable levels after retropubic prostatectomy, their PSA values were equally likely to drop to undetectable levels (65%). Univariate analysis demonstrated two factors that significantly predicted for successful salvage treatment: the absence of seminal vesicle invasion and the absence of lymphovascular invasion. A pretreatment PSA level less than 0.425 ng/mL trended toward statistical significance (P = 0.059). Only seminal vesicle invasion maintained significance on multivariate analysis. The RT was well tolerated, and the gastrointestinal and genitourinary toxicity was largely Radiation Therapy Oncology Group grade 1.

CONCLUSIONS

Salvage RT is moderately effective in treating patients with locally persistent or recurrent prostate adenocarcinoma. Seminal vesicle invasion and lymphovascular invasion predicted for unsuccessful treatment.

Calculations of specific absorbed fractions of the gastrointestinal tract using a realistic whole body tomographic model

Assessment of organ doses from internally deposited radionuclides involves the use of predetermined specific absorbed fractions (SAFs). Many tabulations of SAFs have been derived from Monte Carlo transport simulations using stylized computational models that are not fully realistic of human internal organ anatomy. This paper presents the results of a study to calculate SAFs in the gastrointestinal (GI) tract using a recently developed tomographic model VIP-Man and the EGS4 Monte Carlo radiation transport code. Results show that, for some energies and source-target combinations, considerable discrepancies exist between these results and those from earlier studies, suggesting a need to evaluate existing data carefully by comparison with realistic models.

Acute side effects during 3-D-planned conformal radiotherapy of prostate cancer. Differences between patient's self-reported questionnaire and the corresponding doctor's report

BACKGROUND

Radiotherapy-induced side effects are often scored retrospectively according to the EORTC/RTOG scores for organs at risk by reviewing the medical records. Some studies could prove an over- or underestimation of side effects as assessed by the medical professionals. The aim of this study was to prospectively evaluate differences in side effects as described by the doctors and the patients.

PATIENTS AND METHODS

47 patients with prostate cancer were questioned about their side effects by a radiotherapist and asked to fill in a questionnaire at the start, in the middle and at the end of radiotherapy. The data of this questionnaire and the doctor's report were scored according to the German version of the EORTC/RTOG scores for gastrointestinal (GI) and genitourinary (GU) side effects and subsequently compared. We distinguished between "moderate" disagreement (better/worse by one grade, assessed by the doctor) and "pronounced" disagreement (better/worse by two grades, assessed by the doctor).

RESULTS

The number of GI and GU side effects increased during radiotherapy both according to data obtained from the doctor and the patient questionnaire. Comparing doctors' reports with patients' questionnaires, for GI side effects an agreement was found in 22/47 patients, "moderately better" scores by the doctor's report were found in 13/47 patients, and "moderately worse" scores in 9/47 patients on average. "Pronouncedly better and worse" scores were found in 2/47 patients. For GU side effects an agreement was seen in 22/47 patients, "moderately better" scores in 17/47 patients and "moderately worse" scores in 3/47 patients. Regarding GU side effects, only pronouncedly better scores, as assessed by the doctor, were found in a mean of 4/47 patients. If the EORTC/RTOG score is used in its original English version, a difference is found, particularly in the assessment of GU side effects, resulting in an higher amount of agreement concerning GU side effects and a minor amount of "pronounced disagreement".

CONCLUSION

In order to evaluate radiation-induced side effects, a patient's self-reported questionnaire should be included in the analysis of morbidity, above all for grade 0, 1, and 2 side effects. The validity of data seems to be questionable, particularly in the assessment of grade 0, 1 and 2 side effects, if only data from the doctors' reports are taken into account. The German version of the EORTC/RTOG score--not including the pretreatment status--leads to different results, particularly in the assessment of grade 0, 1, and 2 urinary side effects, which asks for a revision.

Effective doses in standard protocols for multi-slice CT scanning

The purpose of this study was to assess the radiation exposure of patients in several standard protocols in multi-slice CT (MSCT). Scanning protocols for neck, chest, abdomen, and spine were examined on a Somatom Plus 4 Volume Zoom MSCT (Siemens, Erlangen, Germany) with changing slice collimation (4x1, 4x2.5, and 4x5 mm), and pitch factors (1, 1.5, and 2). Effective doses were calculated from LiF-TLD measurements at several organ sites using an Alderson-Rando phantom and compared with calculations using the weighted CTDI. Effective dose for MSCT of the neck was 2.8 mSv. For different protocols for MSCT of the chest, 7.5-12.9 mSv were found. In abdominal MSCT protocols, effective dose varied between 12.4 and 16.1 mSv. The MSCT of the spine may lead to 12 mSv. An excellent correlation between the effective dose as determined by LiF-TLD and the calculated effective dose using the weighted CTDI could be demonstrated; however, a difference of up to 30% (mean 14.3%) was noted. Standard protocols for MSCT as measured in this study showed effective doses of up to16 mSv. Phantom measurement data show a good correlation to estimations using the weighted CTDI.

Late morbidity profiles in prostate cancer patients treated to 79-84 Gy by a simple four-field coplanar beam arrangement

PURPOSE

To describe the frequency and magnitude of late GI and GU morbidity in prostate cancer patients treated to high dose levels with a simple three-dimensional conformal technique.

METHODS AND MATERIALS

A total of 156 intermediate- and high-risk patients were treated between January 1, 1992 and February 28, 1999 with a simple four-field three-dimensional conformal technique to 79-84 Gy. All patients were treated with a four-field conformal technique; the prostate received 82 Gy and the seminal vesicles and periprostatic tissue 46 Gy. GI and GU toxicity was scored according to the Radiation Therapy Oncology Group/European Organization for Research and Treatment of Cancer Late Morbidity Grading Scale and compared using Kaplan-Meier estimates.

RESULTS

The late Grade 2 GI complication rate was 9% and 38% at 3 years for patients treated with and without rectal blocking, respectively (p = 0.0004). No Grade 3 late GI complications developed. The rate of Grade 2 late GU complications was 5%, 8%, and 12% at 12, 24, and 36 months, respectively. The Grade 3 late GU complication rate was 2% at 36 months. These differences were not statistically significant.

CONCLUSION

The treatment method described is a simple four-field conformal technique that can be easily implemented in the general radiation community. A dose of 79-84 Gy can be safely delivered to the prostate, with a 9% rate of late Grade 2 GI, 12% rate of late Grade 2 GU, and 2% rate of late Grade 3 GU complications.

Influence of a single gamma-irradiation on rat microflora

Changes in leukocyte counts and in the gut microflora of laboratory rats irradiated with single whole-body dose of gamma rays (5.0 Gy) were determined. The number of leukocytes was lower especially 1 and 2 weeks after irradiation. A significant decrease in lymphocytes was observed 1 week and in monocytes 1 and 2 weeks after irradiation. In parallel with these changes, an increase in common microflora was observed; some microorganisms, which normally are not present in duodenum, liver and mouth cavity, were detected in these organs.

Doses to organs and tissues from radon and its decay products

This paper discusses the doses from radon and from its short-lived decay products to a number of organs and tissues and to the foetus. The aim is to put all these doses into context rather than concentrating only on the largest contributions. There is also a brief discussion of the evidence from epidemiology on the risks of exposure to radon and its decay products. As is well known, under normal circumstances the greatest hazard is to the respiratory tract from inhalation of radon decay products. Radon decay products may also give substantial doses to skin. Under some circumstances it seems likely that ingested radon could give significant doses to the stomach. Other risks appear to be smaller; the results given here allow them to be compared.

Association of rectal toxicity with thermal dose parameters in treatment of locally advanced prostate cancer with radiation and hyperthermia

PURPOSE

Although hyperthermia has been used for more than two decades in the treatment of pelvic tumors, little is known about the potential impact of heat on rectal toxicity when combined with other treatment modalities. Because rectal toxicity is a concern with radiation and may be exacerbated by hyperthermia, definition of the association of thermal dose parameters with rectal toxicity is important. In this report, we correlate rectal toxicity with thermal dose parameters for patients treated with hyperthermia and radiation for prostate cancer.

METHODS AND MATERIALS

Thirty patients with T2b-T3b disease (1992 American Joint Committee On Cancer criteria) enrolled in a Phase II study of external beam radiation +/- androgen-suppressive therapy with two transrectal ultrasound hyperthermia treatments were assessed for rectal toxicity. Prostatic and anterior rectal wall temperatures were monitored for all treatments. Rectal wall temperatures were limited to 40 degrees C in 19 patients, 41 degrees C in 3 patients, and 42 degrees C in 8 patients. Logistic regression was used to estimate the log hazard of developing National Cancer Institute Common Toxicity Criteria Grade 2 toxicity based on temperature parameters. The following were calculated: hazard ratios, 95% confidence intervals, p values for statistical significance of each parameter, and proportion of variability explained for each parameter.

RESULTS

Gastrointestinal toxicity was limited to Grade 2. The rate of acute Grade 2 proctitis was greater for patients with an allowable rectal wall temperature of >40 degrees C. In this group, 7 of 11 patients experienced acute Grade 2 proctitis, as opposed to 3 of 19 patients in the group with rectal wall temperatures limited to 40 degrees C (p = 0.004). Preliminary assessment of long-term toxicity revealed no differences in toxicity. Hazard ratios for acute Grade 2 proctitis for allowable rectal wall temperature, average rectal wall Tmax, and average prostate Tmax were 9.33 (p = 0.01), 3.66 (p = 0.03), and 2.29 (p = 0.08), respectively. A model combining these three parameters explained 48.6% of the variability among groups.

CONCLUSION

Rectal toxicity correlates with maximum allowable rectal wall temperature, average rectal wall Tmax, and average prostate Tmax for patients undergoing transrectal ultrasound hyperthermia combined with radiation for treatment of advanced clinically localized prostate cancer. Further definition of this association of thermal dose parameters with rectal toxicity in treatment of pelvic malignancies with hyperthermia should advance the goal of delivering thermal therapy in an effective yet safe manner.

Report on an interagency workshop on the radiobiology of nuclear terrorism. Molecular and cellular biology dose (1-10 Sv) radiation and potential mechanisms of radiation protection (Bethesda, Maryland, December 17-18, 2001)

The events of September 11, 2001 have focused attention on the possibility of nuclear terrorism, and 1-10 Sv is arguably the dose range of biological interest, since doses in this range both pose a risk of acute effects and are potentially survivable. Because of this interest, a coalition of U.S. government agencies (NCI, DOD, DOE) and the Radiation Research Society convened a workshop in December 2001 "to focus on molecular, cellular and tissue changes that occur [at doses of 1-10 Sv] and potential mechanisms of radioprotection". A draft report of this workshop was posted on the NCI website in February 2002. According to the draft, the workshop was also intended to "determine the research opportunities and resources required [and] develop a research-action plan for further discussion and implementation." Injuries after exposure to ionizing radiation are important to patients with cancer and to populations potentially subject to accidental or intentional exposure. In these populations, partial- or whole-body exposures in the range of 1-10 Sv are possible. The consequences of exposure of limited tissue volumes to doses above 10 Sv have been researched because of their applicability to cancer therapy, while exposure to doses below 1 Sv has been researched because of nuclear fallout and space exploration issues. Except for research aimed at protection of members of the armed forces, the intervening dose range has received relatively little attention. The workshop participants concluded that although we currently have only a limited ability to deal with the consequences of radiation exposures in this range, focused research would have the potential of rapidly expanding such capabilities.

Removal of a mis-swallowed long spoon via gastrotomy--a case report

Foreign body ingestions are a frequent occurrence, a common presentation at emergency departments, but long, pointed-end metallic spoon swallowing is an uncommon occurrence. Unlike most cases of foreign-body ingestion, there have been no cases of spontaneous passage reported. Consequently, prompt removal is recommended before complications develop. We report a case of accidental ingestion of a long, pointed metallic spoon which failed to pass through the gastrointestinal tract and be excreted. This patient was managed successfully with gastrotomy to remove the object. We recommend this approach for the removal of long pointed foreign bodies to avoid complications developing.

Biology of mucosal pain

Pain is experienced when injury to mucosal tissues occurs. Although the neurobiology of mucosal pain has not been fully elucidated, research has demonstrated that the oral mucosa contains primary afferent nociceptors that respond to thermal, mechanical, and chemical stimuli. Inflammation occurs during the initial phase of mucosal injury caused by stomatotoxic chemotherapy or radiation therapy. This article reviews the mechanisms that underlie acute pain in inflamed cutaneous tissue and summarizes the major mediators that activate and sensitize primary afferent nociceptors. Recommendations for future research to elucidate the neurobiology of mucosal pain throughout the gastrointestinal tract are presented.

Chronobiology of the mammalian response to ionizing radiation. Potential applications in oncology

Ionizing radiation from all sources under appropriate conditions leads to cell death and tissue damage. It is used in cancer treatment under the assumption of a higher radiosensitivity of the fast dividing tumor cells as compared with adjacent host tissues. The radiosensitivities of proliferating host tissues like bone marrow and gastrointestinal lining epithelium are dose limiting. Since these host tissues and many tumors show circadian and other periodicities in their cell proliferation, the timing of radiation treatment according to host and/or tumor rhythms is expected to improve the toxic/therapeutic ratio of the treatment. The experimental data on the chronobiology of radiation exposure show circadian rhythmicity in radiation response after whole body irradiation in mice and rats with highest toxicity in light-dark 12h:12h synchronized animals during their daily activity span. Bone marrow toxicity as well as gastrointestinal epithelial damage show circadian rhythms in part due to radiation damage to the stem cells involved and especially in the intestine also due to damage to the microvasculature. Chronoradiotherapy of malignant tumors seems promising, alone or in combination with response modifiers, provided the host and potential tumor rhythms can be monitored.

Consequential late effects in normal tissues

Unconventional, more aggressive irradiation protocols are usually associated with aggravation of acute reactions. In recent clinical studies, this has resulted in modulation of late effects in the same organ. This phenomenon has been termed consequential late effect (CLE). Correlations between acute and late effects have been reported in a number of tissues. Moreover, some radiobiological parameters may be used to differentiate between consequential and generic late effects: Dose fractionation and overall treatment time have a similar effect on acute and consequential responses, but opposing effects on generic late effects. Modulation of acute effects will affect the consequential component of late sequelae. Similarly, it will be influenced by the irradiated volume if a volume effect exists for the acute response. Moreover, markers for the acute response should be predictive for consequential effects. The present review gives preclinical and clinical evidence for CLE. These are predominantly found in organ systems where the acute response (of the epithelial lining) is associated with an impairment of the barrier against mechanical or chemical stress, which may cause additional trauma to the underlying tissues. Therefore, CLE are mainly found in the urinary and intestinal system, in mucosa and, to some extent, in skin. In these tissues with a consequential component of the late sequelae, amelioration of the acute response to irradiation may be a useful approach to minimize late side effects of effective radiation therapy.

Protection of mouse jejunum against lethal irradiation by Podophyllum hexandrum

Radiation induced gastrointestinal damage occurs due to the destruction of the clonogenic crypt cells and eventual depopulation and denudation of the villi. P. hexandrum, a plant, known for its antitumour activity, has been shown to protect the mice against whole body lethal (10 Gy) irradiation. Present study was undertaken to investigate the radioprotective effect of P. hexandrum on jejunal villi cells, crypt cells, their proliferative capacity and mitigation of apoptosis. In an in vivo micro colony survival assay, pre-irradiation administration of P. hexandrum (-2 h) increased the number of surviving crypts in the jejunum by a factor of 3.0 (P < 0.05) and villi cellularity by 2.7 (P < 0.05) fold in comparison to irradiated control. Pre-irradiation administration of P. hexandrum reduced the incidence of apoptotic bodies in the crypts (P < 0.05) in a time dependent manner and depicted a mitotic arrest till the 24 h. However, after 84 h the percentage of mitosis was observed to be nearly similar to that of unirradiated control. This study suggests that arrest of cell division may help in protecting the clonogenic cells against radiation. It would be interesting to investigate further the role of P hexandrum in influencing various cell cycle regulators like bcl-2, TGF-beta, Cyclin-E etc.

An estimation of radiation doses to benthic invertebrates from sediments collected near a Canadian uranium mine

A new method is described for calculating radiation doses to benthic invertebrates from radionuclide concentrations in freshwater sediment. Both internal and external radiation doses were estimated for all 14 principal radionuclides of the uranium-238 decay series. Sediments were collected from three sites downstream of a uranium mining operation in northern Saskatchewan, Canada. Sediments from two sites, located approximately 1.6 and 4.4 km downstream from mining operations, yielded absorbed doses to both larval midges, Chironomus tentans, and adult amphipods, Hyalella azteca, of 59-60 and 19 mGy/year, respectively, compared to 3.2 mGy/year for a nearby control site. External beta radiation from protactinium-234 (234Pa) and alpha radiation from uranium (U) contributed most of the dose at the impacted sites, whereas polonium-210 (210Po) was most important at the control site. If a weighting factor of 20 was employed for the greater biological effect of alpha vs. beta and gamma radiation, then total equivalent doses rose to 540-560 mGy/year at the site closest to uranium operations. Such equivalent doses are above the 360-mGy/year no-observed-effect level for reproductive effects in vertebrates from gamma radiation exposure. Data are not available to determine the effect of such doses on benthic organisms, but they are high enough to warrant concern. Detrimental effects have been observed in H. azteca at similar uranium concentration in laboratory toxicity tests, but it remains unclear whether the radiotoxicity or the chemotoxicity of uranium is responsible for these effects.

Brief note and evaluation of acute-radiation syndrome and treatment of a Tokai-mura criticality accident patient

Patient A who was exposed to a critical dose of radiation developed skin lesions throughout the body surface, gastrointestinal disorder with massive diarrhea and prominent bleeding, which caused severe loss in body fluids. Gastrointestinal bleeding due to the deteriorated intestinal mucosa was considered to be one of the major causes of death, although infection did not develop, possibly because of SDD and aseptic intensive care, until terminal stages. Patient A ultimately developed respiratory and renal failure in addition to skin exudate and gastrointestinal bleeding, and died of multiple organ failure on the 83rd day after exposure. The extreme unevenness of the dose distribution and the neutron versus y-ray component made the clinical manifestation very complicated. Initially, the mean absorbed dose was calculated as 16-20 GyEq for Patient A, mainly based on neutron-activated 24Na in the blood. However, a very recent calculation showed that the absorbed skin dose was highest at the upper-right abdomen reaching 61.8 Gy (27.0 as neutron plus 34.8 Gy as y-ray). The dorsal side was calculated to have received one eighth of the value of the abdominal side, and much smaller neutron component. His absorbed-dose distribution throughout the body was very inhomogeneous because of the closeness of the standing point to the mixing tank. Despite prolonged survival because of intensive care with massive fluids and blood transfusion, peripheral blood stem-cell transplantation, cultured skin-cell grafts, and the administration of cytokines for marrow, the patient was not saved. Restoration of the bone marrow function, prevention of skin fibrosis, radiation lung damage, and repair of gastrointestinal mucosa, and final recovery of the patient were elusive. Abundant personnel and resources were also a prerequisite to allow for the comprehensive and collective intensive care. A further understanding of the effects of high-dose radiation as well as the basic and clinical development of regeneration medicine are important issues for the future.

The example of gastrointestinal damage induced by ionising radiation: are there accessible markers?

Ionising radiation exposure occurs during radiotherapy, diagnostic tests or by accident. In all cases the gastrointestinal tract, which is highly sensitive to radiation, may be at risk. Each region may respond differently to radiation exposure which to some extent is reflected by clinical symptoms. The evaluation of injury, whether acute or chronic, depends on the utilization of a variety of techniques. It appears that no definitive tests exist and that a multiparametric analysis should be undertaken. This review addresses the question of accessible markers associated with radiation-induced intestinal pathologies. Several approaches are discussed which include clinical observations, measurement of faecal parameters, changes in inflammatory mediators and possible applications of imaging techniques.