Sequential chemo-radiotherapy in non-small cell lung cancer

Locally advanced non-small cell lung cancer (NSCLC) stage IIIA/IIIB represents approximately 30% of NSCLC and still has a poor prognosis. In this article we give a short review on several randomized phase III trials that showed a slight but significant survival benefit for sequential chemo-radiotherapy in the treatment of locally advanced NSCLC.

Light scatter and DNA accessibility to propidium iodide of ataxia telangiectasia and fanconi anemia cells

Cells from individuals with genetic diseases ataxia telangiectasia (AT) and Fanconi anemia (FA) exhibit hypersensitivity to ionizing radiation (AT) or DNA cross-linking agents (FA) which may be caused by multiple factors including defects in chromatin structure and DNA repair. In this study, a combination of cytometric techniques was employed to study the chromatin conformation of AT and FA cells. Nuclei of peripheral blood mononuclear cells (PBMCs) and of skin fibroblasts established from AT and FA patients were analyzed by light scattering and fluorimetric titration with the DNA-intercalating dye propidium iodide. The light scatter measurements revealed the presence of small-sized nuclei with reduced granularity in PBMCs and fibroblasts from both AT and FA patients. The fluorometric titration data could be interpreted by assuming two classes of propidium iodide binding sites with different affinities. The number of high-affinity sites in AT and FA fibroblasts was significantly larger (by 20%) than in control cells. Our findings show the applicability of cytometric techniques for the rapid assessment of chromatin conformation and also suggest the possibility to identify AT and FA carriers.

Intensified hyperfractionated accelerated radiotherapy limits the additional benefit of simultaneous chemotherapy--results of a multicentric randomized German trial in advanced head-and-neck cancer

PURPOSE

To demonstrate the efficacy of radiochemotherapy (RCT) as the first choice of treatment for advanced unresectable head-and-neck cancer. To prove an expected benefit of simultaneously given chemotherapy, a two-arm randomized study with hyperfractionated accelerated radiochemotherapy (HF-ACC-RCT) vs. hyperfractionated accelerated radiotherapy (HF-ACC-RT) was initiated. The primary endpoint was 1-year survival with local control (SLC).

METHODS AND MATERIALS

Patients with Stage III and IV (UICC) unresectable oro- and hypopharyngeal carcinomas were randomized for HF-ACC-RCT with 2 cycles of 5-FU (600 mg/m(2)/day)/carboplatinum (70 mg/m(2)) on days 1--5 and 29--33 (arm A) or HF-ACC-RT alone (arm B). In both arms, there was a second randomization for testing the effect of prophylactically given G-CSF (263 microg, days 15--19) on mucosal toxicity. Total RT dose in both arms was 69.9 Gy in 38 days, with a concomitant boost regimen (weeks 1--3: 1.8 Gy/day, weeks 4 and 5: b.i.d. RT with 1.8 Gy/1.5 Gy). Between July 1995 and May 1999, 263 patients were randomized (median age 56 years; 96% Stage IV tumors, 4% Stage III tumors).

RESULTS

This analysis is based on 240 patients: 113 patients with RCT and 127 patients with RT, qualified for protocol and starting treatment. There were 178 oropharyngeal and 62 hypopharyngeal carcinomas. Treatment was tolerable in both arms, with a higher mucosal toxicity after RCT. Restaging showed comparable nonsignificant different CR + PR rates of 92.4% after RCT and 87.9% after RT (p = 0.29). After a median observed time of 22.3 months, l- and 2-year local-regional control (LRC) rates were 69% and 51% after RCT and 58% and 45% after RT (p = 0.14). There was a significantly better 1-year SLC after RCT (58%) compared with RT (44%, p = 0.05). Patients with oropharyngeal carcinomas showed significantly better SLC after RCT (60%) vs. RT (40%, p = 0.01); the smaller group of hypopharyngeal carcinomas had no statistical benefit of RCT (p = 0.84). For both tumor locations, prophylactically given G-CSF was a poor prognostic factor (Cox regression), and resulted in reduced LRC (log-rank test: +/- G-CSF, p = 0.0072).

CONCLUSION

With accelerated radiotherapy, the efficiency of simultaneously given chemotherapy may be not as high as expected when compared to standard fractionated RT. Oropharyngeal carcinomas showed better LRC after HF-ACC-RCT vs. HF-ACC-RT; hypopharyngeal carcinomas did not. Prophylactic G-CSF resulted in an unexpected reduced local control and should be given in radiotherapy regimen only with strong hematologic indication.

Radiation-induced reduction of BMP-induced proteoglycan synthesis in an embryonal mesenchymal tissue equivalent using the chicken "limb bud" test

PURPOSE

Heterotopic ossification (HO) is a common complication following total hip replacement. Clinical studies showed the effectiveness of irradiation for prevention of heterotopic ossification. The mechanism of radiotherapy responsible for the reduction of heterotopic ossification is unclear. The purpose of this study was to find a suitable cell system, which can reproduce in-vitro data resulting from clinical in-vivo studies. The establishment of such a cell model allows detailed analyses of the mechanism of radiotherapy.

METHOD

The chicken limb bud test was used as an in-vitro model. The cells acquired by the limb bud test were irradiated with different doses (0 Gy, 3 Gy, 7 Gy, 10 Gy, 20 Gy). Irradiation was set either 1 hour before, or 1 or 3 days after BMP-2 incubation. The synthesis of proteoglycans (PGS) upon treatment with bone morphogenetic protein (BMP)-2 was measured in cells incubated with BMP-2 for 4 days followed by 35SO4(2-) labeling for 6 hours. Labeled proteoglycans were precipitated using Alcian blue and measured in a raytest radio-TLC analyzer. The incubation with BMP-2 was defined to correlate the in-vivo stimulus meaning the operation.

RESULTS

The proteoglycan synthesis was significantly reduced by irradiation 1 hour before or 1 day after BMP-2 incubation, if the dosage was at least 7 Gy. Higher doses than 7 Gy did not lead to lower proteoglycan levels. There was only a trend for a reduction of proteoglycan synthesis by 3 Gy irradiation, but no significant difference compared to the non-irradiated control. An irradiation 3 days after BMP-2 incubation had no effect on proteoglycan.

CONCLUSION

A dose and time dependent effect of radiation on BMP-2-induced proteoglycan synthesis was observed. Therefore the results of clinical in-vivo studies were reproduced exactly by the limb bud test. We established an in-vitro cell model to analyze the mechanism of the prevention of heterotopic ossification by radiotherapy on cellular or sub-cellular level.

Soft X-ray therapy of recurrent pterygium--an alternative to 90Sr eye applicators

BACKGROUND

Analysis of effectiveness of perioperative 20 kV soft X-ray irradiation in recurrent pterygium as an alternative to postoperative 90Sr beta irradiation.

PATIENTS AND METHODS

Between 1987 and 2000 a total of 65 patients with 81 pterygia were treated with 20 kV X-ray therapy in the course of surgical treatment of recurrent pterygium. Until 1995 simple excision (bare sclera technique) followed by postoperative irradiation (generally four fractions of 5 Gy) was applied, with radiation starting on mean 4 days following surgery (34 cases, mean follow-up 52 months). Since 1995 we have changed our policy to a perioperative regimen starting with a single dose of 7 Gy prior to microsurgical excision with conjunctival autograft and proceeding within 24 hours with 5 Gy single dose to the surgical bed and then every other day to a total dose of 27 Gy (47 cases, mean follow-up 31 months). Recurrence rate was calculated by Kaplan Meier method. A multivariate Cox regression analysis of prognostic factors for recurrence was performed.

RESULTS

A total of 19 recurrences were observed, 15 in the historical postoperative group and four in the perioperative group. Actuarial 2- and 5-year recurrence rate is 9% in the "new treatment group" compared to 34% and 56% in the historical group (p = 0.001). Only one of the four recurrences among the pre- and postoperatively irradiated group required a new surgical procedure. In this case radiation had been terminated at 17 Gy. Actuarial rate of surgical reintervention was only 2% at 2 and 5 years compared to 28% and 36% in the historical group. In multivariate Cox regression analysis only the new treatment strategy was found to influence control rate significantly. Until now no case of severe side effects like scleral necrosis or thinning, symble-pharon, radiation-induced cataract or glaucoma were observed in both groups.

CONCLUSION

The combination of pre- and postoperative 20 kV X-ray therapy and microsurgical excision combined with conjunctival autograft is a highly effective treatment to prevent recurrence in the high-risk group of recurrent pterygia and can be recommended as an alternative to postoperative 90Sr beta irradiation.

Intracavitary afterloading boost in anal canal carcinoma. Results, function and quality of life

BACKGROUND

First clinical data on a new intracavitary afterloading boost method for anal canal carcinoma is reported.

PATIENTS AND METHODS

20 consecutive patients (T1 5%, T2 70%, T3 20%, T4 5%; N0 75%, N1 10%, N2 15%; all M0) treated with external beam pelvic radiotherapy (median dose 56 Gy, range 46-64 Gy), simultaneous 5-FU and mitomycin (in 75%) and an intracavitary afterloading boost (one or two fractions of 5 Gy at 5 mm depth) were analyzed after a mean +/- SD follow-up for living patients of 4.4 +/- 2.1 years. Quality of Life (QoL) and anorectal manometry parameters were assessed in ten colostomy-free survivors.

RESULTS

Overall, recurrence-free and colostomy-free survival at 5 years were 84%, 79% and 69%, respectively. No death was tumor-related. The only local failure was successfully salvaged by local excision. All three colostomies were performed for toxicity. Resting pressure and maximum squeeze pressure of the anal sphincter were reduced by 51% and 71%, as compared with control subjects, but quality of life was similar compared to healthy volunteers.

CONCLUSION

The described regimen is highly effective but associated with increased toxicity.

Sequential chemo- and radiochemotherapy with weekly paclitaxel (Taxol) and 3D-conformal radiotherapy of stage III inoperable non-small cell lung cancer. Results of a dose escalation study

The purpose of this study was the determination of the maximum tolerable dose (MTD) of weekly paclitaxel (PX) in combination with 3D-conformal radiotherapy in non-small cell lung cancer (NSCLC) and the evaluation of side effects, patient outcome and tumor response. Thirty-eight patients with inoperable NSCLC, UICC-stage IIIA (n=14)/IIIB (n=24) received two cycles of induction chemotherapy with PX/carboplatin followed by combined radiochemotherapy (60 Gy/6 weeks) with weekly PX which was escalated in cohorts of four patients until dose limiting toxicity (DLT) was reached. Starting level was 40 mg/m(2). 3D-conformal radiotherapy was applied in all patients. Toxicity was determined by WHO criteria. Patients were followed-up 3-monthly. Thirty eight patients have entered the study, 34 patients are evaluable. DLT was esophagitis III degrees, requiring interruption of radiotherapy and was reached at the PX 70 mg/m(2). Two hypersensitivity reactions (50 mg/m(2)) and one leucopenia III degrees (60 mg/m(2)) were observed. Only one patient (60 mg/m(2), 50 Gy) completely aborted treatment. The pneumonitis rate was between 21 and 36% but showed no clear correlation with PX dose. Tumor response (PR and CR) defined by CT-scan 6 weeks following radiotherapy was 88% (30/34). The 1- and 2-year survival rate is 73% and 34%. We conclude that the MTD of weekly PX with 60 Gy normofractionated radiotherapy is 60 mg/m(2). The DLT is esophagitis. Response and survival data of this sequential/combined approach are promising. A minor increase of pulmonary toxicity of irradiation is suspected.

Response to X-irradiation of Fanconi anemia homozygous and heterozygous cells assessed by the single-cell gel electrophoresis (comet) assay

Fanconi anemia (FA) is an autosomal recessive disorder characterized by bone marrow failure and cancer susceptibility. Patient cells are sensitive to a variety of clastogens, most prominently cross-linking agents. Although there is the long-standing clinical impression of radiosensitivity, in vitro studies have yielded conflicting results. We exposed peripheral blood mononuclear cells from FA patients and carriers to x-rays and determined their DNA damage and repair profiles using the alkaline single-cell gel electrophoresis (comet) assay. Studies were carried out in two independent series of experiments by two laboratories using different protocols. The cells of both FA patients and carriers showed uniformly high initial DNA damage rates as assessed by the total initial tail moment. In addition, the average residual tail moment at 30 to 50 minutes and the repair half-time parameters were significantly elevated. These findings suggest an increased release of fragmented DNA following x-ray exposure in cells that carry one or two mutations in one of the FA genes. The comet assay may be a useful adjunct for heterozygote detection in families of FA patients.

p53 and Ki-67 as predictive markers for radiosensitivity in squamous cell carcinoma of the oral cavity? an immunohistochemical and clinicopathologic study

PURPOSE

Previously published data relating the expression of p53 and Ki-67 to radiation response in head and neck cancer are conflicting. This may be due to differences in patient selection and treatment modalities. In this study of a homogenous population of patients with oral cavity cancer, Ki-67 and p53 indices were correlated with histopathologically assessed tumor regression after preoperative radiochemotherapy and longterm outcome.

METHODS AND MATERIALS

Eighty-eight patients with squamous cell carcinoma of the oral cavity and treated between September 1985 and November 1995 by preoperative radiochemotherapy and definitive surgery were included in this analysis. By immunohistochemistry (IHC) the pre-irradiation expression of p53 and of Ki-67 were analyzed and correlated with the histopathologically proven tumor regression, overall survival and local control.

RESULTS

The overall 2- and 5-year survival rates were 76.5% and 63%, the locoregional control rates were 84% and 79%, respectively. After preoperative radiochemotherapy 29 patients (33%) showed complete tumor regression (ypT(0) classification). Survival and local control rates were significantly higher for patients showing ypT(0) classification than ypT(1-4) classification (p < 0.01). This effect was independent of pretreatment tumor classification in multivariate analysis. Pre-irradiation p53 status and Ki-67 index had no influence on tumor regression and clinical outcome in these patients.

CONCLUSION

Complete tumor regression after preoperative treatment is related to an improved outcome in combined modality treatment of oral cavity cancer. The presented study could not demonstrate an influence of p53 and Ki-67 status as detected by immunohistochemical staining on survival, local control, or tumor regression after radiochemotherapy.

The in vitro colony assay: a predictor of clinical outcome

PURPOSE

To determine the predictive power of an in vitro colony assay on the clinical normal-tissue complication rate.

MATERIAL AND METHODS

Primary skin fibroblasts from 88 individuals were generated from the skin biopsies of patients who received a standardized radiotherapy. Tissue was cultured for three to six passages, irradiated with doses between 1 and 8 Gy under defined conditions, seeded and finally the colonies were stained and counted after 10-14 days. The survival curves were fitted by the L-Q model and the SF2, alpha/beta and plating efficiency were calculated.

RESULTS

The parameters SF2 and plating efficiency were stable throughout the 4-year test period. Intra-individual differences between repeated experiments were significantly lower than inter-individual test results. For the observed acute skin and late normal-tissue reactions other than skin the in vitro parameter SF2 correlated significantly (p<0.005). For late skin reactions this correlation was not found.

DISCUSSION

In contrast to other publications, a clear correlation was found between the in vitro test results and clinically observed early reactions. The lack of correlation for late skin reactions suggests that the combination of intrinsic radiation sensitivity and exogenous factors may alter the clinically observed reaction of certain tissues to a different extent.

The Internet as a source of medical information. Investigation in a mixed cohort of radiotherapy patients

BACKGROUND

The widespread use of the internet has influenced patterns of medical information for tumor patients. The present study examines the use of various media and, in particular, the application of the internet, in a mixed cohort of radiotherapy patients.

PATIENTS AND METHODS

All patients undergoing radiotherapy at the University of Würzburg were analyzed simultaneously in May of 2000 using a newly developed 9-item questionnaire. Questions related to the importance of various media for medical information (grading from 0 = unimportant to 2 = very important) and previous internet use. The data was correlated with clinical information from the patients' charts.

RESULTS

In 95% of patients (n = 139) questionnaires were evaluable. Of 8 media, television (mean score 0.94), patient brochure (0.83) and newspaper (0.76) were considered most important for medical information while the internet ranged last (0.24). Whereas 61.2% knew the internet as a source of medical information, only 11.5% had searched the internet themselves and 15.1% had received internet information from family or friends. Only 24.1% from these 2 groups had discussed the information with their physician. The rates of internet use were substantially higher in subgroups with younger age, higher education and palliative treatment.

CONCLUSION

The importance of the medium internet for the information of tumor patients is currently still low but likely to increase based on demographic factors.

Stereotactic radiotherapy of extracranial targets: CT-simulation and accuracy of treatment in the stereotactic body frame

BACKGROUND AND PURPOSE

Evaluation of set-up accuracy and analysis of target reproducibility in the stereotactic body frame (SBF), designed by Blomgren and Lax from Karolinska Hospital, Stockholm. Different types of targets were analyzed for the risk of target deviation. The correlation of target deviation to bony structures was analyzed to evaluate the value of bones as reference structures for isocenter verification.

MATERIALS AND METHODS

Thirty patients with 32 targets were treated in the SBF for primary or metastatic peripheral lung cancer, liver metastases, abdominal and pelvic tumor recurrences or bone metastases. Set-up accuracy and target mobility were evaluated by CT-simulation and port films. The contours of the target at isocenter level, bony structures and body outline were compared by matching the CT-slices for treatment planning and simulation using the stereotactic coordinates of the SBF as external reference system. The matching procedure was performed by using a 3D treatment planning program.

RESULTS

Set-up accuracy represented by bony structures revealed standard deviations (SD) of 3.5 mm in longitudinal, 2.2 mm in anterior-posterior and 3.9 mm in lateral directions. Target reproducibility showed a SD of 4.4 mm in longitudinal, 3.4 mm ap and 3.3 mm in lateral direction prior to correction. Correlation of target deviation to bones ranged from 33% (soft tissue targets) to 100% (bones).

CONCLUSION

A security margin of 5 mm for PTV definition is sufficient, if CT simulation is performed prior to each treatment to correct larger target deviations or set-up errors. Isocenter verification relative to bony structures is only safe for bony targets but not for soft tissue targets.

[Results of radiotherapy in rectal carcinoma]

Adjuvant combined radio-chemotherapy in rectal cancer is indicated in stage UICC II and III (pT3/4 and/or pN+) without distant metastases (exception: resectable metastases of the liver). Radiotherapy alone improves local control in the pelvis. A statistical significant improvement of survival is only achievable in combination with systemic chemotherapy. In Germany neo-adjuvant, conventional fractionated radio-chemotherapy over five weeks is applied in patients with surgically inoperable tumors to achieve a "down-staging" with improvement of resectability. Neo-adjuvant radiotherapy of operable rectal cancer in five fractions of high single doses within one week has revealed a statistical significant improvement of survival if compared to surgery alone in the Swedish rectal cancer trial, but is not standard in Germany yet. The influence of technical advances in surgery as total mesorectal excision (TME) on indications of adjuvant therapy is evaluated in prospective randomized studies at this time.

Radiation techniques for head and neck tumors

PURPOSE

A technique that combines some advantages of conforming techniques for advanced oro- and hypopharyngeal carcinomas is proposed. The aim is to increase the dose homogeneity in the target volume relative to lateral opposed fields.

METHODS AND MATERIALS

This publication compares conforming radiation techniques based on standard equipment, standard linear accelerator setup and commercially available planning software with lateral opposed fields. More advanced conformal techniques reported in the literature are taken into account in a semi-quantitative manner. Our standard method uses an arc rotation, sparing the spinal cord. In contrast to earlier methods of this type, the resulting dose deficit in the vicinity of the spine is compensated by static lateral wedged fields. Dose distributions for 25 consecutive patients were planned.

RESULTS

The conforming techniques were found to produce more homogeneous dose distributions than lateral opposed fields. In the planning target volume (PTV) (mean: 940 cm(3)) a standard deviation of dose of 4.6% was achieved. Ninety-five percent of the PTV were enclosed by the 90% isodose. The maximal spinal cord dose was limited to 45 Gy. The dose distributions of these techniques could compete with literature data on advanced techniques (the published dose-volume histogram (DVHs) of PTVs were evaluated). At the linear accelerator time for realization took 14 min on average. The planning time is 1-4 h (mean: less than 2 h).

CONCLUSION

A rotational technique applicable with standard equipment is presented. Dose coverage of target volumes is improved, while the spinal cord is spared.

The influence of the radicality of resection and dose of postoperative radiation therapy on local control and survival in carcinomas of the upper aerodigestive tract

PURPOSE

To evaluate dose concepts in postoperative irradiation of carcinomas of the upper aerodigestive tract according to the radicality of resection.

PATIENTS AND METHODS

In a retrospective analysis, the charts of 257 patients with histologically-proven carcinoma of the upper aerodigestive tract (40 T1, 80 T2, 53 T3, 84 T4 tumors, with nodal involvement in 181 cases) were reviewed according to the radicality of resection and dose of irradiation administered. Sixty-four patients had tumor-free resection margins (> 3 mm), 66 patients had close resection margins (< 3 mm), and 101 patients had R1 resections, and 26 patients had R2 resections. A median dose of 56 Gy was applied to the primary tumor bed and the cervical lymphatics (2 Gy/fraction, 5 fractions/week). In cases of R1 or R2 resection, or of close margins (< 3 mm), the tumor bed or, respectively, tumor residuals were boosted with doses up to a median of 66 Gy. Locoregional tumor control and survival was investigated by uni- and multivariate analyses according to T-, N-stage, grade of resection, total dose of radiation, and presence or absence of extracapsular tumor spread and lymphangiosis carcinomatosa.

RESULTS

An overall 3- and 5-year survival rate of 60% and 45%, respectively, was achieved. Rates for freedom from locoregional recurrence were 77% and 72% at 3 and 5 years, respectively. The survival rates according to the grade of resection at 5 years were 67% for patients resected with tumor-free margins, 59% for patients resected with close margins, 26% for patients with R1 resection, and 27% for patients with R2 resection. Within a median follow-up period of 4.7 years for living patients, a total of 67 recurrences (26%) were observed (in 9% of patients resected with tumor-free margins, in 27% with close margins, in 37% of R1 resected, and in 19% of R2 resected patients). Freedom from locoregional recurrence at 3 years was achieved in 100% of the patients resected with tumor-free margins, in 92% of patients resected with close surgical margins, in 87% of R1 and 69% of R2 resected patients. In multivariate Cox-regression analysis, the variables grade of resection (p = 0.00031) and total dose of irradiation (p = 0.0046) were found as factors influencing locoregional control. Variables influencing survival according to multivariate analysis are T-stage (p = 0.0057), N-stage (p = 0.024), grade of resection (p = 0.000015), total dose of irradiation (p < 0. 000000). Extracapsular tumor spread and lymphangiosis carcinomatosa are factors of borderline significance (p = 0.055, p = 0.066).

CONCLUSION

In postoperative radiotherapy of head and neck carcinomas, doses adapted to the risk of locoregional recurrent disease should be applied. Patients with R1 and R2 resections should be treated with doses of more than 68 Gy (2 Gy/fraction, 5 fractions/week) (with close margins [< 3 mm] more than 66 Gy) to achieve an improvement in locoregional control and survival.

[Optimized 3-D planning by simple means. An example]

AIM

A treatment technique favorable for linacs with asymmetric jaws, which combines cranio-caudal matching fields with fields enclosing the whole target volume, is investigated with respect to field matching and sparing of normal tissue and organs at risk.

PATIENT AND METHODS

For a pelvic target volume rapidly varying in cranio-caudal direction a 5-field technique was planned with individually weighted and blocked fields. Three fields adjoining in cranio-caudal direction were completed by 2 fields enclosing the whole target volume. The matching line was measured and calculated with Helax TMS. Furthermore a 4-field box and opposing fields were planned. The dose-volume histograms for target, bladder, intestine and soft tissue were exported. Normal tissue complication probability and tumor control probability, respectively, were calculated for all techniques.

RESULTS

In the region of the matching line the summation of the measured normalized curves resulted in relative dose maxima of 6.0% (caudal) and 4.5% (cranial), respectively. For fields enclosing the whole target volume the dose maxima in the region of the matching line decreased to 2.0% (caudal) and 1.8% (cranial), respectively. For the dose profiles calculated with Helax TMS no overdose was found. The 5-field technique with adjoining fields results in a better sparing of the organs at risk compared to the other techniques, whereas the tumor control remains the same.

CONCLUSIONS

In specific cases a technique with cranio-caudal adjoining fields can be recommended with respect to sparing of normal tissue and organs at risk.

A new verification film system for routine quality control of radiation fields: Kodak EC-L

BACKGROUND

The use of modern irradiation techniques requires better verification films for determining set-up deviations and patient movements during the course of radiation treatment. This is an investigation of the image quality and time requirement of a new verification film system compared to a conventional portal film system.

MATERIAL AND METHODS

For conventional verifications we used Agfa Curix HT 1000 films which were compared to the new Kodak EC-L film system. 344 Agfa Curix HT 1000 and 381 Kodak EC-L portal films of different tumor sites (prostate, rectum, head and neck) were visually judged on a light box by 2 experienced physicians. Subjective judgement of image quality, masking of films and time requirement were checked.

RESULTS

In this investigation 68% of 175 Kodak EC-L ap/pa-films were judged "good", only 18% were classified "moderate" or "poor" 14%, but only 22% of 173 conventional ap/pa verification films (Agfa Curix HT 1000) were judged to be "good".

CONCLUSIONS

The image quality, detail perception and time required for film inspection of the new Kodak EC-L film system was significantly improved when compared with standard portal films. They could be read more accurately and the detection of set-up deviation was facilitated.

Transcranial sonography: integration into target volume definition for glioblastoma multiforme

PURPOSE

Recent studies indicate that transcranial sonography (TCS) reliably displays the extension of malignant brain tumors. The effect of integrating TCS into radiotherapy planning for glioblastoma multiforme (GBM) was investigated herein.

METHODS AND MATERIALS

Thirteen patients subtotally resected for GBM underwent TCS during radiotherapy planning and were conventionally treated (54 to 60 Gy). Gross tumor volumes (GTVs) and stereotactic boost planning target volumes (PTVs, 3-mm margin) were created, based on contrast enhancement on computed tomography (CT) only (PTV(CT)) or the combined CT and TCS information (PTV(CT+TCS)). Noncoplonar conformal treatment plans for both PTVs were compared. Tumor progression patterns and preoperative magnetic resonance imaging (MRI) were related to both PTVs.

RESULTS

A sufficient temporal bone window for TCS was present in 11 of 13 patients. GTVs as defined by TCS were considerably larger than the respective CT volumes: Of the composite GTV(CT+TCS) (median volume 42 ml), 23%, 13%, and 66% (medians) were covered by the overlap of both methods, CT only and TCS only, respectively. Median sizes of PTV(CT) and PTV(CT+TCS) were 34 and 74 ml, respectively. Addition of TCS to CT information led to a median increase of the volume irradiated within the 80% isodose by 32 ml (median factor 1.51). PTV(CT+TCS) volume was at median 24% of a "conventional" MRI(T2)-based PTV. Of eight progressions analyzed, three and six occurred inside the 80% isodose of the plans for PTV(CT) and for PTV(CT+TCS), respectively.

CONCLUSION

Addition of TCS tumor volume to the contrast-enhancing CT volume in postoperative radiotherapy planning for GBM increases the treated volume by a median factor of 1.5. Since a high frequency of marginal recurrences is reported from dose-escalation trials of this disease, TCS may complement established methods in PTV definition.

Influence of treatment technique on dose-volume histogram and normal tissue complication probability for small bowel and bladder. A prospective study using a 3-D planning system and a radiobiological model in patients receiving postoperative pelvic irradiation

PURPOSE

A prospective study was undertaken to evaluate the influence of pelvic irradiation techniques on the dose-volume histograms of organs at risk and to analyze its possible clinical relevance using radiobiological models.

PATIENTS AND METHODS

For 20 patients receiving postoperative pelvic irradiation because of rectal cancer a 3-field technique (3-FT), a 4-field technique (4-FT) and an opposing field technique (OFT) were designed by a 3-D planning system (Helax, TMS). Dose-volume histograms (DVH) of small bowel, urinary bladder and planning target volume (PTV) were analyzed. The normal tissue complication probability (NTCP) was determined by the radiobiological model of Lyman and Kutcher using the tolerance data of Emami.

RESULTS

Median dose to the PTV did not differ between the 3 techniques (3-FT/4-FT/OFT: 99.2%/98.6%/98.1% of the prescribed dose; p > 0.05). Although the median dose to the urinary bladder was lower for the 3-FT than for the 4-FT (44.7% vs 60.3%; p < 0.001), there was no difference in the calculated NTCP (0.0% vs 0.0%; p > 0.05). Using multiple field techniques both the dose to and the treated volume of the urinary bladder were significantly lower than using the OFT. As a consequence of this the late NTCP of the bladder was higher for the OFT (5.46%). Although the median dose to the small bowel was lower for the 3-FT than for the 4-FT (30.8% vs 54.5%; p < 0.005), the fractional part of small bowel within the high-dose region (90% isodose) was higher for the 3-FT (10.6% vs 8.2%; p > 0.05). Thus the calculated NTCP was higher for the 3-FT (0.79 vs 0.44) than for 4-FT. For the OFT the median dose to small bowel was 69.9% and the small bowel volume within the high-dose region was 57.8% resulting in a late NTCP of 9.36% (OFT vs 3-FT/4-FT: p < 0.05).

CONCLUSION

Using multiple field techniques both the dose to the organs of risk and the fractional part of risk organs within the high-dose region can be reduced significantly. As a consequence of this a lower NTCP was calculated for the 3-FT and the 4-FT than for the OFT. Using the biological model a small, but significant difference between a 3-FT and a 4-FT was demonstrated in favor to the 4-FT.