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Biomedical subjects

D J Joseph

Publications and source records attributed to D J Joseph.

At least 37 records · Page 2Linked to original sources
PubMed1993

Phase I/II study of concurrent weekly carboplatin and radiation therapy in advanced head and neck cancer.

Thirty-two patients with locally advanced head and neck cancer have been treated with concurrent weekly carboplatin and conventional radiation therapy (RT) (2 Gy fractions 4-5 days/week to a total dose of 64-70 Gy over 7-8 weeks) in a Phase I/II study. Carboplatin was administered weekly during RT at doses of 75-150 mg/m2/wk as a 1-hour infusion. The maximum tolerated dose of carboplatin was 130 mg/m2/wk, with myelosuppression, predominantly neutropenia, being dose limiting. Other systemic toxicities were insignificant and no overlapping toxicity was evident. Ultimate locoregional control and survival probabilities were disappointing. It is suggested that either further studies using radiation and carboplatin at the dose 130 mg/m2/wk, or variations on dose and scheduling be performed prior to the instigation of Phase III studies.

Adult↗
PubMed1993

Pelvic radiotherapy with concurrent 5-fluorouracil modulated by leucovorin for rectal cancer: a phase II study.

Combined modality treatment for cancer of the rectum has been shown to reduce recurrences and improve overall survival. We wished to find out if we could safely give concurrent radiotherapy and 5-fluorouracil (5-FU) modulated by leucovorin (LV) in 3 settings: pre-operatively, adjuvantly and in recurrent disease. A total of 39 patients were treated, 11 preoperatively, 17 adjuvantly and 11 with recurrent disease. There were 26 males and 13 females with a median age of 64 years. The median radiotherapy (RT) dose was 45 Gy/25 fractions/1.8 Gy per fraction (range 25-63 Gy). Chemotherapy consisted of LV 80 mg/m2 i.v. infusion over 1.5 hours followed by 5-FU 400 mg/m2 i.v. bolus, both given once a week. The median number of cycles was 8 (range 3-12). Diarrhoea was the main toxicity, and was encountered in 30 patients (77%): grade 1 in 3 (8%), grade 2 in 12 (30%), grade 3 in 11 (28%), and grade 4 in 4 (10%). This required 18 (46%) patients to have modifications to their RT (20% had breaks and 26% ceased at doses < 45 Gy). Nine patients (23%) had modifications in the chemotherapy (10% had breaks and 13% received < 6 cycles). Encouraging responses were seen in the preoperative setting. Concurrent RT and 5-FU/LV, as given in this schedule, results in an unacceptable incidence of diarrhoea, limiting both the total dose of RT and chemotherapy that can be delivered, particularly in patients who have had previous surgery.

Adenocarcinoma↗
PubMed1992

Tangential breast irradiation: simple improvements.

A series of studies using phantom and in vivo dosimetry measurements with diodes and thermoluminescent dosimetry were undertaken to establish whether simple methods are available to obtain improvements in homogeneity of dose in the treated breast, and reductions of dose to tissues outside it, when using tangential 6MV photon fields. These studies confirmed that the use of an appropriate lung density correction factor in the planning process is likely to cause a reduction in the amount of wedge compensation predicted to be necessary to produce reasonable dose homogeneity in the central axis of the beam. This was shown to be of value in eliminating potential areas of overdosage in the chest wall medial and lateral to the breast mound, and also in reducing unwanted doses to the contralateral breast and lung. Further reductions in dose to contralateral breast were confirmed to occur when the majority, or all, of the wedge compensation predicted necessary is placed on the lateral field and when the lateral tangential field is angled anteriorly in such a way as to align the posterior beam edges. Skin does above, below, and over the breast mound were observed to depend critically upon angle of incidence of the beam, with its consequent effect upon electron build-up, and the position of the breast contour in the beam. Skin doses above and below the breast mound were shown to exceed over the mound itself. This differential effect was observed to increase with increasing wedge compensation. In some situations skin doses below the breast mound nearly reached prescribed dose within the breast. The design and use of simple lead attenuators to reduce these areas of high dosage is discussed.

Breast Neoplasms↗
PubMed1992

Treatment and planning decisions in non-small cell carcinoma of the lung: an Australasian patterns of practice study.

Fourteen practising radiation oncologists were surveyed to assess their treatment and planning habits utilizing six sample cases of non-small cell carcinoma of the lung. Respondents were first given a general questionnaire, designed to evaluate their theoretical treatment and planning recommendations based on various tumour and patient related variables. Respondents then undertook a practical planning exercise utilizing planning CT and simulator radiographs for each of the six sample cases. Each case was accompanied by a brief history and report outlining specific tumour stage and non-stage related variables. The practical planning exercise was repeated on the second day of the survey utilizing different non-stage related variables but identical radiology and stage-related information. This design enabled firstly, a comparison of clinicians' intended policy and planning methods with actual policy and planning decisions, and secondly, an assessment of intra-clinician variability in decision making and planning practice. Good agreement was evident among clinicians with respect to general, non-case specific treatment policies; however, very significant variation occurred at an inter- and intra-clinician level and involved the entire treatment and planning process for individual cases. Despite identical treatment intent across identical radiological case pairings, clinicians chose widely differing margins and target volumes in their planning exercise. Treatment intent appeared to be influenced more by non-stage related variables rather than stage related information and radiological appearances per se. We have shown that experienced radiation oncologists do not adhere to stated case selection criteria and show inconsistencies in their treatment planning for non-small cell carcinoma of the lung.

Australia↗
PubMed1990

Low dose rate teletherapy using a telecaesium 137 unit radiobiological, physical and clinical considerations.

Low dose rate teletherapy aims to combine the supposedly superior results obtained with low dose rate implants with the convenience and staff protection characteristics of external beam therapy. Previous investigators have used telecobalt units to produce dose rates of 1.1 to 1.8 Gy/hr to treat in daily sessions lasting 6-10 hours to total doses of 60-70 Gy. These studies have not discounted the possibility that much of the advantage of interstitial implants results from the low dose rates used per se, and from the fact that the total dose is delivered in a short overall time. The relationship between total dose, dose rate and volume giving normal tissue and anit-tumour effects, however, remains ill-defined. At the Newcastle Mater Misericordiae Hospital a Caesium teletherapy unit has been modified to treat at low dose rates and a study has been designed with a view to establish which permutations of total dose and dose rate are isoeffective for acute mucosal and acute skin reactions in the dose rate range between 0.8 and 9.6 Gy/hr (1.3 and 16 cGy/min).

Cesium Radioisotopes↗
PubMed1990

CT scanning for definitive radiotherapy planning of prostate cancer: necessity or nicety? Results from survey of radiation oncologists working at different institutions in Australasia.

Interactive computerised tomographic (CT) planning techniques offer the prospect of better anatomical localisation, more consistent tumour coverage, and limiting normal tissue dose. However, its value in the management of prostate cancer remains undefined. The present study addresses the impact of planning CT on the designated target volumes for localised carcinoma of the prostate at a multi-institution national level. Nine radiation oncologists from different centres in Australia and New Zealand were asked to designate a target volume on five sample patients with different disease stages (A2-C2) using both conventional cystogram films and planning CT scans. Target volumes estimated by CT means in this study differed by more than 10% from those estimated by conventional means in 75.6% of instances, being smaller in 55.6%. Volumes varied widely between individual radiation oncologists, both using conventional planning and CT information. These variations were found to exceed any differences in the volume caused by the planning technique itself. Results from this survey suggest that volumes appear to change more according to the individual radiation oncologist rather than to any other factor. In most or all of the sample cases six of nine radiation oncologists defined the borders of their CT volumes to be either consistently smaller (5 out of 9) or greater (1 out of 9) than their conventionally defined borders. The results of this survey are potentially important and warrant repetition with larger sample numbers in other countries where interactive CT planning facilities exist, both with and without diagnostic radiological input, to exclude similar variation and to define causes for any variations that do become apparent.

Data Collection↗
PubMed1977

Recurrent laryngeal nerve injury following thyroid operations.

Preoperative and postoperative laryngoscopy should be performed with thyroid operations. A prospective study of 121 thyroid operations from June 1970 to December 1974 was analyzed. There was a 4.2 per cent recurrent laryngeal nerve injury incidence in 217 nerves at risk, four of nine injuries being permanent. Of 217 superior laryngeal nerves at risk, 1.4% were injured, one of three permanently. Previous thyroid operations may place the laryngeal nerves at a greater risk. Transient edema of the laryngeal nerve in 13.4% of the patients was believed due to endotracheal intubation. There seemed to be no difference in the incidence of injury whether the nerves were seen or palpated. It is recommended that indirect laryngoscopy be performed in the course of evaluating thyroid disorders.

Humans↗