Technical note: a fast laser-based optical-CT scanner for three-dimensional radiation dosimetry.

PURPOSE: To introduce a novel laser-based optical-CT scanner for the readout of three-dimensional (3D) radiation dosimeters. METHODS: The scanner employs a diode laser, a cylindrical lens, a motorized linear rail, a rotation stage, and a charge-coupled device camera. The scanner operates in a translate-rotate fashion and may be set up in two configurations depending on the orientation of the cylindrical lens. The attenuation coefficient versus dose response was determined for a normoxic N-vinylpyrrolidone based polymer gel dosimeter. Cylindrical dosimeters, 2 cm diameter, were homogenously irradiated to known doses up to 60 Gy using a 6 MV linear accelerator. For a test irradiation, a 5 cm diameter dosimeter was irradiated along its cylindrical axis using a rectangular 1 cm x 1 cm irradiation beam. The dose readout of this scanner was compared to the corresponding readout of a common wide illumination and area detector optical-CT scanner. RESULTS: The attenuation coefficient versus dose response of the laser-based system was found to be linear up to 60 Gy (r2 = 0.997) compared to the wide field illumination based optical-CT scanner, which exhibits linearity up to 32 Gy (r2 = 0.996). The noise in the reconstructed attenuation coefficient maps was +/- 7.2 x 10(-2) mm(-1) versus +/- 9.5 x 10(-3) mm(-1) for the laser-based system and the wide field illumination system, respectively. CONCLUSIONS: We have developed a novel laser-based optical-CT scanner, which is capable of generating fast 3D dosimetric data using a scattering polymer gel dosimeter. Our data demonstrate that the dose readout of this scanner preserves the advantage of existing laser-based optical-CT scanners in providing measurements, which are minimally affected by scattered light. For accurate reconstruction of the attenuation coefficients, noise reduction techniques need to be applied.

Conformal radiotherapy of prostate cancer: what is the proper technique for sparing organs-at-risk?

The aim of the current study was to evaluate the optimal coplanar technique for conformal radiotherapy of prostate cancer. Twelve inoperable patients with prostatic carcinoma were examined. Five different techniques with three-, four- and six-fields were applied for treatment of prostate and seminal vesicles with or without lymph nodes. Treatment techniques were compared by using rectum, bladder and femoral heads dose-volume histogram data. A three-field arrangement consisting of an anterior and two lateral portals resulted in the maximum rectal sparing irrespectively of the irradiated area. The maximum femoral head sparing was achieved by the technique consisting of six oblique and lateral fields. The maximum bladder protection was observed with the box technique for treatment with large pelvic fields and with the arrangement consisting of two oblique and two lateral portals for conedown irradiation. In conclusion, the presented data allow the radiotherapists to select the proper irradiation technique associated with the maximum sparing of each organ-at-risk.

Hypofractionated radiotherapy in non small cell lung cancer: a review of the current literature.

Hypofractionated irradiation has an established role in the palliative treatment of patients with advanced medically inoperable non - small cell lung cancer (NSCLC ) and poor performance status. Also hypofractionated radiotherapy merits careful consideration in the curative treatment of patients with Stage I and II disease using contemporary technology. The biological effect of radiation on tumours is increased as the overall treatment time is shortened. Hypofractionated field radiotherapy offers acceptable palliation with minimal toxicity. The rates of palliation for hemoptysis , chest pain , cough and dyspnea reported from studies with very short regimen ( 8,5 Gy x 2 ), are comparable to those of other trials that used more protracted palliative treatment . The observed toxicity is minimal, and no cases of oesophagitis, pneumonitis, or radiation myelopathy developed. The minimal toxicity is a reflection of both the low biologic total dose and the tight RT design. Therefore the radiation side effects appear to be related to the technique of RT delivered rather than the patient's PS. Hence, widely believed dogmas concerning the tolerance of critical structures to conventionally fractionated doses, such as the dose-volume effect, total dose, and time (latency) dependency, has to be re-evaluated for hypofractionated radiation therapy. As well there is data suggesting that the small stages I - II NSCLC are likely to benefit from hypofractionated regimens too. Hypofractionated stereotactic radiotherapy is a new technically complex approach to the treatment of early-stage nonsmall cell lung cancer. It is capable to deliver much higher doses to the cancer than is possible with standard techniques, and as a result, rates of tumour control are high and similar to what can be achieved by surgical resection. Refinements of technique and dose as well as randomized data are required before stereotactic radiotherapy can be endorsed as a standard of care for patients with inoperable peripherally located T1 non small cell lung cancer. A clear advantage of the very short hypofractionated palliative regimen is that it allows patients with a short expected survival time to spend more of their remaining time away from the hospital.

First-line intra-arterial chemotherapy (IAC) with epirubicin and mitoxantrone in locally advanced breast cancer.

BACKGROUND: Approximately 20% of patients with breast cancer present with locally advanced disease without distant metastases. This phase II double-center trial aimed at investigating the activity of epirubicin (Farmorubicin)--mitoxantrone (Onkotrone/Novantrone) combination as first-line intra-arterial chemotherapy (IAC) in locally advanced breast cancer patients. PATIENTS AND METHODS: Thirty-six patients with locally advanced disease and no prior exposure to anthracyclines received the following regimen: epirubicin (Farmorubicin) 30 mg/mq and mitoxantrone (Onkotrone/Novantrone) 10 mg/mq by IAC short infusion on day 1, every 3 weeks for up to six cycles. Prior to IAC an arteriogram of subclavian, internal mammary and lateral thoracic arteries was obtained in all patients, followed by infusion of a blue dye solution into the arteries to determine the most appropriate vessel that supplies the tumor area. RESULTS: Objective responses, confirmed at least 4 weeks after the first documentation, were observed in 25 patients (70%; 95%CI, 62% to 80%): 3 CR, 22 PR. Although three of the patients showed complete tumor regression, operative removal or toilet mastectomy became feasible in 25 patients since tumor shrinkage ranged over 75%. A total of 25 mastectomies were carried out for 36 patients. Four patients had bulky tumors (> 13 cm tumor diameter), while 8 patients had ulcerated tumors, two of which presented with complete infiltration of normal breast tissue. The median time to progression and median overall survival were 11 and 27 months, respectively. The time to local response was 3 weeks and time to mastectomy was 9 weeks. Transient neurological disorders developed in six patients and skin chemical burns with painful inflammatory reactions were encountered in ten patients. No systemic toxicity was observed in terms of bone marrow depression and hair loss. No cardiotoxicity was observed. In all specimens necrosis was reported (complete 3 cases, partial 16 and minimal 6). CONCLUSION: A combination of epirubicin (Farmorubicin) and mitoxantrone (Onkotrone/Novantrone) as IAC appears to be a safe and well tolerated treatment for locally advanced breast cancer without clinical evidence of distant metastases. When combined with surgery it offers interesting results in terms of local control and allows a high rate of mastectomies in otherwise inoperable cases.

Mammographic findings and occupational exposure to pesticides currently in use on Crete.

This is a preliminary report of an outreach mammographic-screening programme on Crete. The screening is part of a study to test if occupational exposure to pesticides in greenhouses (mainly organophosphates and organocarbamates), may increase the risk of malignant or premalignant findings in mammographic examination. A total of 1062 women (aged 40--75 years) were recruited between 1988 and 1993 and followed-up until 1998: 522 worked for at least 10 years in greenhouses for more than 4 h daily (exposed), and 540 never worked in agriculture (non-exposed). Statistics include detection rates and relative risks of mammographic findings. 'Exposed' women had a significantly (P<0.05) higher risk than 'non-exposed' for fibroadenoma, ductal hyperplasia, sclerotic adenosis, fibrohyperplastic disease, cystic disease and inflammatory mastitis. There were no significant differences in the detection rates of fibrocystic changes, lipoma and malignant changes or malignant tumours. Compared with older women (aged 50--75 years), younger women (aged 40--49 years), particularly in the 'exposed' group, had a higher detection rate of malignant tumours. These preliminary results indicate that 'exposed' women may have higher risks of incidence for a number of lesions, which are risk markers for subsequent invasive breast cancers. They confirm also that early screening for breast cancer is effective and provides an opportunity for a reduction in breast cancer mortality.

Treatment of unresectable malignant abdominal, pelvic and thoracic tumors using abdominal pelvic and thoracic stop-flow chemotherapy.

BACKGROUND: Stop-flow perfusion (SFP) has been recently used to enhance the effects of chemotherapy in patients with locally advanced tumors. PATIENTS AND METHODS: Over a 2-year period we performed abdominal, pelvic and thoracic SFP in 12 patients with unresectable or metastatic tumors, using balloon catheters inserted into the abdominal aorta and inferior vena cava. Blood flow was occluded and hypoxic extracorporeal perfusion or SFP was performed for advanced diseases. The chemotherapeutic agents were directly administered into the aorta and/or inferior vena cava for thoracic SFP. The procedure was repeated in each patient, with one-month interval between sessions. Haemofiltration was also applied in two patients with generalized abdominal disease in order to reduce systemic toxicity. RESULTS: At post-operative CT or MRI follow-up, tumor shrinkage of more than 50% was observed in six patients, while post-SFP chemotherapy surgical resection of the tumors became feasible in four cases. The relief of pain, wherever present, was dramatic in the immediate post-operative period. Overall clinical improvement was achieved in all 12 patients. Post-operative recovery was uneventful in all but two patients, who developed minor systemic toxicity. CONCLUSION: SFP appears to be a safe technique with low morbidity which improves the quality of life of cancer patients and allows satisfactory control of locally advanced tumors and metastatic carcinomatosis.

Transurethral 137Cs medium dose rate radiotherapy as a boost for small-sized localized prostatic carcinomas.

The aim of this study is to present preliminary experience with 137Cs medium dose rate (MDR) afterloading transurethral radiotherapy for small-sized (< 2.5 cm) prostatic carcinomas. The phase II protocol comprises 46 Gy of external beam radiotherapy, followed by two insertions (1 week apart) of 137Cs MDR transurethral brachytherapy, each one delivering 8 Gy to a point 0.5 cm from the urethral walls. The treatment is completed with a 14-Gy boost to the prostatic area through lateral external beam fields. Up to now, 9 patients have been treated. The transurethral insertion is a simple procedure, requires no anesthesia and the ultrasonographic observation precisely and easily guided the positioning of the applicator. All 9 patients are alive and disease-free 12-36 months after the end of radiotherapy. One of them presented a mild degree of urethral stricture and none developed chronic proctitis or cystitis. Seven patients were sexually potent before radiotherapy and all of them maintained their potency. Transurethral radiotherapy for prostatic carcinoma requires further investigation. The radiation dose that the procedure delivers to the prostate is higher than the one prescribed for external beam irradiation regimens. Rectal and bladder dose is substantially reduced. Although the prostatic urethra receives a higher dose, the incidence of urethral stricture is low probably because of the small tissue volume (8 cm3) in the high radiation dose area.

Unresectable colorectal-carcinoma - 10 years experience with patients treated with radical or palliative external-beam radiotherapy in Greece.

Our analysis presents a group of 86 patients with unresectable colorectal cancer who were treated with radical or palliative external beam radiotherapy from 1979-1990 at the Radiation Oncology Department of Greek Anticancer Institute, St. Savvas Hospital, Athens. The dose applied to the tumor area was 20-50 Gy in 2-6 weeks. A CAT-scan guided boost field portal to the primary tumor bed and immediately adjacent nodes was also used. Irradiation was given with a Co-60 unit or a 6 MeV Linear Accelerator using a two, three or 4-field technique. Complete symptomatic relief was achieved in 90% of patients with rectal bleeding, 63% with pain and 37% with mucous discharge. Although the majority of our patients received a higher than 40Gy radiation dose, we have seen symptomatic relief in up to 90% of patients treated with 20-30 Gy in 2-3 weeks. However, the duration of improvement in symptomatic relief of our patients was better for those who had been given higher doses of radiation therapy. The radiation dose was sufficient to relieve symptoms in 40 patients (46.5%) for more than 12 months and in 20 patients (23.2%) for 8-12 months.