Brief histories of medical physics in Asia-Oceania.

The history of medical physics in Asia-Oceania goes back to the late nineteenth century when X-ray imaging was introduced, although medical physicists were not appointed until much later. Medical physics developed very quickly in some countries, but in others the socio-economic situation as such prevented it being established for many years. In others, the political situation and war has impeded its development. In many countries their medical physics history has not been well recorded and there is a danger that it will be lost to future generations. In this paper, brief histories of the development of medical physics in most countries in Asia-Oceania are presented by a large number of authors to serve as a record. The histories are necessarily brief; otherwise the paper would quickly turn into a book of hundreds of pages. The emphasis in each history as recorded here varies as the focus and culture of the countries as well as the length of their histories varies considerably.

Extracorporeal Irradiation in Malignant Bone Tumors.

Extracorporeal irradiation (ECI) is relatively a rare method used in the management of malignant bone tumors (MBT). It consists of en block removal of the tumor bearing bone segment, removal of the tumor from the bone, irradiation and re implantation back in the body.

Radiotherapy for benign diseases.

Radiotherapy mainly involves treatment of patients with malignant tumors. Even with recognition of the risks of late skin injury, carcinogenesis, leukemogenesis, and genetic damage from all ionizing radiation; radiation therapy also continues to be accepted treatment for benign diseases. Before initiation, the quality of irradiation, total dose, overall time, underlying organs at risk, and shielding factors should be considered. Children should be treated with ionizing radiation only in very exceptional cases and after weighing the pros and cons of the therapy. Direct irradiation of skin areas overlying organs that are particularly prone to late effects (e.g. thyroid, eye, gonads, bone marrow and breast) should be avoided. Radiation protection techniques should be used in all instances. The depth of penetration of the x-ray beam should be chosen according to the depth of the pathologic process. Choice of beam energy usually depends on the depth of the target volume; every effort is made to spare normal underlying tissue in superficial lesions. There are a number of other benign conditions that can be treated with radiotherapy; we present a brief overview of some of the commonly encountered conditions.

Curative interstitial brachytherapy for early stage carcinoma lip.

Brachytherapy is potentially useful in the treatment of head-and-neck cancers, because most tumor sites, such as the lip, tongue, floor of mouth, tonsil, pharynx, nasopharynx, sinuses, and neck, are accessible for the placement of afterloading applicators and catheters. It has the advantage of delivering a higher radiation dose to the tumor while sparing surrounding normal tissue from radiation. Furthermore, the overall treatment duration is shorter, and the dose distribution confirms to tumor shape. Brachytherapy is used as "monotherapy" for the treatment of small primary tumors or recurrent disease after external beam radiation therapy (EBRT). Small cancers of the lip (less than 2 cm) are treated equally well with surgery or radiation therapy with excellent cosmetic and functional results seen in radiation therapy. We treated an 18-year old male diagnosed as stage I carcinoma lip with curative interstitial brachytherapy. He was treated to a dose of 3 Gy per fraction, two fractions per day at interval of 6 hours between the two fractions for 6 days. He therefore received a total dose of 36 Gy with High Dose Rate (HDR) Brachytherapy, which is equivalent to 58.36 Gy conventional radiotherapy dose. At two months follow, the patient is clinically disease free and has no complaints.

Endocavitary radiotherapy in carcinoma oesophagus.

Radiation therapy is often used in an attempt to palliate or cure oesophageal neoplasms. However, the radiation tolerance of the normal structures around the oesophagus (heart, lung and spinal cord) restricts the radiation dose that can be delivered. We used a nasogastric catheter to deliver High Dose Intra-luminal Iridium-192 irradiation for carcinoma of the oesophagus using HDR-Varisource machine. This technique for treatment of carcinoma of the oesophagus can help overcome the dose restraints. The external beam radiation dose was about 46 Gy and the intra luminal dose was 5 Gy at 1 cm from central axis. These after loading procedures are simple, fast and accurate and can be used to boost external radiation therapy doses. Since the intra luminal boost delivers a high-localized dose with little side effects, this simple technique should be used to obtain palliation, delay tumour progression, reduce overall treatment time and attempt to improve survival in patients with oesophageal neoplasm. Intra luminal brachytherapy helps achieve good palliation in these neoplasms.

Radiotherapy for splenomegaly.

Radiotherapy for massive, symptomatic splenomegaly has been used in a palliative setting since the early 1990's. Massive splenomegaly may be seen in CML, CLL, hairy cell leukemia and splenic marginal zone lymphomas, prolymphocytic leukemia, myeloproliferative disorders such as polycythaemia rubra, polycythaemia vera or essential thrombocytosis or myelofibrosis. Splenic radiation therapy has been shown to be effective in palliation of the signs and symptoms due to massive splenomegaly. We present here one such case of myelofibrosis where the patient was treated with radiotherapy to the spleen for symptomatic relief. The patient achieved excellent response to the treatment.