Superficial X-ray Research Articles

A comparison of late cosmetic results following two different radiotherapy techniques for treating basal cell carcinoma

Fractionated superficial X-ray therapy and gold grain brachytherapy Elastoplast mould (EPM) methods of treating basal cell carcinoma (BCC) on facial skin were compared for long term cosmesis. Thirty patients were traced who had been treated successfully for a BCC on the face more than ten years previously. Late skin and subcutaneous changes were graded. Fifteen had been treated with 116 kV X-rays (32.5 Gy in five fractions on 5 consecutive days, and the remaining 15 with radioactive gold EPMs, delivering a dose of 6000–6500 R with an application lasting 7 days). The late cosmetic result scores of the patients treated by X-rays gave a mean score of 2.13; only three of these patients had a score of less than 2. The mean score for the patients treated with EPMs was 1.47; none had a score greater than 2. The difference is statistically significant ( P<0.01, Wilcoxon rank sum test). The EPM gave much more acceptable late cosmetic results.

Radiation oncology: An emergence as a discipline in Thailand

It has been a century since Wilhelm Konrad Roentgen discovered the x-ray in 1895. Immediately after it was discovered, the Roentgen Ray was applied for diagnostic purposes in clinical medicine. In 1896, radioactivity was discovered and radium was discovered 2 years later in 1896. Radiation oncology began in Europe in 1898. The Roentgen ray was used in diagnostic clinical work in Thailand since 1928, when the first x-ray machine was installed in Siriraj Hospital by a radiologist, Dr. Pin Muangman, who was trained at Peterbent Brigham Hospital, Harvard University. In 1935, one superficial x-ray machine, lo-15 KeV, and one deep x-ray machine, 230 KeV, were installed, and three doctors, two nurses, and one technician worked in the X-Ray Department. These three doctors were locally trained on the job by the only trained radiologist mentioned above (11, 17). A radiologist at that time mostly worked in the diagnostic side of the clinical work, especially in chest and bone diagnosis. The therapeutic applications of x-rays were mostly confined to the skin diseases. The superficial x-ray was used for eczema, which proved to be resistant to medical treatment. Warts or hyperkeratosis that were recurrent after surgical or electrocautery treatment were referred for xray treatment. Radiotherapy given by deep x-ray machines was confined to palliative or postoperative treatment after a second operation for a local recurrence of cancer cases. The untoward effects of x-rays, such as radiation sickness and painful moist desquamation of the skin, were well known to the public and other medical colleagues. In 1938, Dr. Amnuey Smerasuta was granted a scholarship to study a course of Diploma in Medical Radiology and Electrology in Cambridge and returned to work in the Department of Radiology in 1940. He introduced radium therappy into Thailand. For superficial lesions, he used radium plaques for the treatment of warts, hyperkeratosis, and small hemangiomas, especially in children. For interstitial radium therapy, he used radium needles for carcinoma of the lips, tongue, and buccal mucosa. For treatment of carcinoma of the cervix, he used radium tubes sitting in the intrauterine tandem and radium needles filled in the two boxes for treating each side of the parametrium. The radium applicator for treating the parametria was introduced into the fomices and was called the butterfly applicator. It consisted of a central holding handle and two boxes of radium needles on each side of the central handle. The distances between the two boxes were adjustable by screwing at the central holding handle (11, 17). The intracavitary radium applicator used in Thailand at that time was a modification of the Stockholm techniques. The dosimetry was recorded in mg h. Radiation therapy was gradually accepted in the treatment of Stage I and early stage II of carcinoma of the cervix for curative treatment and Stages III and IV for palliative treatment. Supplemental external radiation to the parametria was given by the deep x-ray 400 KeV. or convergent beam therapy 220 KeV (4, 15). A joint consultation clinic between gynecologists and radiologists (so-called at that time) was created to decide the staging of the diseases jointly. The Stage I carcinoma cervix cases were treated mostly by the Wertheim’s operation. Only the patients who refused surgery or those who had medical contraindications to surgery were referred to be treated by intracavitary radium. In the Department of Surgery, patients who had carcinoma of the lower lip, tongue, and buccal mucosa were referred for interstitial radium followed by radical neck dissection of the regional lymph nodes. In 1951, Dr. Roj Suwansuthi received a scholarship from the Instituted of International Education for postgraduate study in the U.S. and was trained at the Memorial Sloan-Kettering Cancer Center, New York and Peterbent Brigham Hospital, Harvard University. He was the first M.D. from Thailand to receive the diploma of the American Board of Radiology. When he came back to Thailand he was appointed the head of the radiotherapy division and did a lot to improve the standard of radiation therapy in Thailand, especially for external radiation. In 1953, teleradium was introduced into the Army Hospital and at the same time nuclear medicine was intro-

A method for producing uniform dose distributions in the junction regions of large hinge angle electron fields

The planning problems presented by abutting electron fields are well recognized. Junctioning electron fields with a large hinge angle compounds the problems because of the creation of closely situated high dose and low-dose regions. The technique involving a compensated superficial x-ray (SXR) field to treat the junction region between electron fields was developed and used in a particular clinical case (treatment of a squamous cell carcinoma of the forehead/scalp). The superficial x-ray beam parameters were chosen and the compensator was designed to make the SXR field complementary to the electron fields. Application of a compensated SXR field eliminated low dose zones in the junction region and reduced high dose zones to 110%. In the clinical case discussed, the high-dose areas due to the SXR field would not appear because of increased attenuation of the soft X-rays in bone. The technique proposed produces uniform dose distribution up to 3 cm deep and can be considered as an additional tool for dealing with electron field junctioning problems.

Accuracy of Monte Carlo photon transport simulation in characterizing brachytherapy dosimeter energy-response artefacts

Practical dosimeters in brachytherapy, such as thermoluminescent dosimeters (TLD) and diodes, are usually calibrated against low-energy megavoltage beams. To measure absolute dose rate near a brachytherapy source, it is necessary to establish the energy response of the detector relative to that of the calibration energy. The purpose of this paper is to assess the accuracy of Monte Carlo photon transport (MCPT) simulation in modelling the absolute detector response as a function of detector geometry and photon energy. We have exposed two different sizes of TLD-100 (LiF chips) and p-type silicon diode detectors to calibrated , HDR source and superficial x-ray beams. For the Scanditronix electron-field diode, the relative detector response, defined as the measured detector readings per measured unit of air kerma, varied from (40 kVp beam) to ( beam). Similarly for the large and small chips the same quantity varied from and , respectively. Monte Carlo simulation was used to calculate the absorbed dose to the active volume of the detector per unit air kerma. If the Monte Carlo simulation is accurate, then the absolute detector response, which is defined as the measured detector reading per unit dose absorbed by the active detector volume, and is calculated by Monte Carlo simulation, should be a constant. For the diode, the absolute response is . For TLDs of size the absolute response is and for TLDs of it is . From the above results we can conclude that the absolute response function of detectors (TLDs and diodes) is directly proportional to absorbed dose by the active volume of the detector and is independent of beam quality.

Verification of surface dose on patients undergoing low to medium energy X-ray therapy

About 5% of patients still undergo cancer treatment with superficial (peak energy ≤ 120 kVp) X-ray radiation. Dosimetry of these beams is difficult since the maximum dose is delivered at the surface and backscatter contributes significantly to the dose. This is particularly a problem in the difficult geometries encountered in superficial treatments in the head and neck area. It has recently been shown that surface dose measurements in mega-voltage X-ray beams can be performed using TLD (Thermoluminescence Dosimetry) extrapolation. In this technique, LiF TLD chips with a surface area of 3.15 × 3.15 cm 2 and three different thicknesses (0.230, 0.099, and 0.038 g/cm 2) are used together in the same radiation beam which allows the extrapolation of the measured dose back to the true surface. The energy response curve of the three thicknesses of LiF chips was measured for the energy range of 60kVp, HVL 1.6 mm Al to 300kVp, 4 mm Cu. LiF was found to over respond by a factor of 1.7 at 60kVp HVL 1.6 mm Al with respect to a 6MV photon beam. A feasibility study was carried out on three patients undergoing treatment at 120kVp. Because of the small field sizes involved it was necessary to limit irradiation to one or two chips at a time. The dose fall off in the first millimetre of tissue could be clearly detected. TLD extrapolation, in low to medium energy beams, was found to be useful to assess the dose of patients undergoing treatment for superficial lesions.

The changing face of radiation oncology in Australia 1950-1995: a personal view.

In 1950, orthovoltage X-rays were used to treat a wide spectrum of malignant disease but results were impaired by poor depth dose and significant reactions; radium and radon were used commonly and superficial X-ray therapy was used for a large number of skin cancers as well as many benign skin conditions. Since megavoltage X-ray therapy was introduced to Australia and with earlier diagnosis, high standards for qualification as a radiation oncologist set by the Royal Australasian College of Radiologists (RACR), improved imaging and tumour localization, improved beam characteristics, computerization and dosimetry, patients are now better treated with improved local control and less morbidity. Public facilities have been chronically underfunded by governments resulting in waiting lists for treatment, and free standing private practices are important in sharing the ever increasing workload consequent to the increasing and ageing population. The use of brachytherapy has fallen but is enjoying a resurgence of interest. Chemotherapy has emerged. Radiobiology has had some influence on radiation treatment. Health education has improved and the needs and expectations of patients better appreciated and helped. Cancer societies have made an important contribution. Statistical evaluation of treatment is better understood. Undergraduate training and academic positions remain insufficient. The formation of the Faculty of Radiation Oncology of the RACR has given fresh impetus to the specialty.

Electron beam therapy is not inferior to superficial x-ray therapy in the treatment of skin carcinoma

Purpose : To compare recurrence rates and cosmetic results after electron beam therapy vs. superficial x-ray therapy for nonmelanoma skin carcinoma. Methods and Materials : A retrospective analysis was performed on 389 histologically confirmed basal cell and squamous cell cell carcinomas of teh skin, treated with either superficial x-rays or electron beam therapy, with regard to local control rates and cosmetics, as scored with an arbitrary three-point scale. Results : The overall local recurrence rate was 4.9 (19 out of 389). For small tumors (irradiated surfaces ≤ 10 cm 2) a local recurrence rate of 2.2% was observed, both after electron beam therapy and after superficial x-ray therapy. Tumor size and previous treatment proved to be important prognostic factors with regard to control rate. The well-fractionated electron beam therapy yielded better cosmetic results than the large fraction surperficial x-ray therapy. Conclusion : Electron beam treatment is not inferior to superficial x-ray treatment and even better for larger tumors. The inferior results of electron beam therapy reported in literature might be due to technical factors, which are discussed.

Superficial X-Ray Therapy in Keloid Management

Radiotherapy for the management of keloids was introduced in 1906. Eighty-eight years later there is no consensus among physicians who treat keloids that radiotherapy is safe, although it is generally accepted that radiotherapy is effective in reducing the recurrence of keloids following excision. This paper reports on a retrospective study of 24 patients whose keloid postexcisional sites were treated with superficial x-ray therapy. This paper compares the author's results with the results of 18 studies reported by other investigators. The objective of the paper was to determine the effectiveness and safety of superficial x-ray therapy. The paper concludes that superficial x-ray therapy does reduce the rate of postexcisional keloid recurrence. It stresses the need for better controls in reporting on superficial x-ray therapy in keloid management. A multi-institutional prospective study is proposed, and a suggested protocol is outlined. There has been only one case report of a carcinoma occurring subsequent to the treatment of a keloid postexcisional site with radiotherapy, and the causal relation was questionable. A system for long-term follow-up of patients who receive superficial x-ray therapy is proposed.

Dose distribution measurements in superficial X-ray beams using NMR dosimetry

The conversion of Fe2+ to Fe3+ in a Fricke solution due to ionizing radiation can be detected using nuclear magnetic resonance (NMR) imaging. The aim of the present study was to develop a suitable system for the study of dose distributions in superficial radiation beams making use of the water equivalence of the dosimetric gel system. Agarose gels (1.5%) doped with 0.5 mM ammonium ferrous sulphate and 125 mM sulphuric acid were exposed to X-rays from a superficial radiotherapy treatment unit (HVT 1.4, 2.4 and 7.25 mm Al). In the experiments doses between 10 Gy and 20 Gy were given, and the gel surface was in direct contact with the lead glass cone applicators (diameters 1 cm and 2.5 cm) at an FSD of 10 cm. Images were obtained within 4 h after irradiation in the head coil of a 1.5 T clinical MR scanner. Using spin-echo sequences with seven different repetition times between 120 ms and 4 s, the spin-lattice relaxation time (T1) was calculated for specified regions of interest with about 1 mm spacing. The inverse of T1 was shown to be proportional to the given dose and 1/T1 maps were obtained for all three superficial radiation qualities. The depth-dose curves determined with NMR dosimetry compare well with those obtained with a thin-window parallel plate ion chamber and thermoluminescence dosimetry in the same radiation beams.

Lentigo Maligna of the Head and Neck

Although surgical excision is considered the treatment of choice for lentigo maligna, some elderly patients presenting with large lesions in the head and neck region may not be suitable candidates for surgical management. Radiotherapy has been used for this tumor at the Princess Margaret Hospital, Toronto, Ontario, for over the past 20 years with encouraging results. Fifty-four patients treated between 1968 and 1988 were identified, and their records were reviewed to determine treatment outcome. Younger patients with smaller lesions were treated with surgical excision (n = 18) and achieved an actuarial tumor control rate of 94% at 3 years. Older patients with larger lesions located in the head and neck area were treated by radiotherapy (n = 36), with an actuarial tumor control rate of 86% at 5 years. Three of the four patients not achieving tumor control by radiation were successfully treated with surgical excision, and two of them proved to have malignant melanomas (both Clark's level II) when examined histologically. One patient with residual pigmentation 4 months after treatment was unavailable for follow-up. No patients developed metastatic melanoma. The late cosmetic appearance was acceptable in the majority of irradiated patients, with 11% showing poor cosmesis due to progressive skin pallor, atrophy, and telangiectasia in the treated area. Conventional fractionated radiation therapy with superficial x-rays is a simple and effective method of management for lentigo maligna of the head and neck region. It is an excellent alternative treatment to surgical excision, with low morbidity and acceptable long-term cosmetic results.

Radiation therapy for non-aids associated (classic and endemic African) and epidemic Kaposi's sarcoma

Purpose : A retrospective analysis of patients with non-AIDS and AIDS-related Kaposi's sarcoma, who were treated with radiation therapy. Methods and Materials : Between 1978 and 1992, 56 patients with one of the three major types (classical, endemic, epidemic) of Kaposi's sarcoma received radiation therapy as their sole treatment modality. Extent of fields, daily fractionation, and total dose were applied on a clinical basis. These lesions received superficial x-ray therapy, Co-60 teletherapy, or 6–8 MeV electron beams. Field sizes depended on extent of the lesion. Total dose administration ranged from 8–12 Gy in one exposure, or a total of 24–30 Gy fractionated over 2–3 weeks. Results : The majority of patients responded to radiation therapy. Symptomatic relief was achieved in 80–100% of patients irrespective of the type of Kaposi's sarcoma, treatment modality, or schedule. Side effects were tolerable in all but three patients with epidemic type Kaposi's sarcoma, who developed severe mucositis. Conclusion : Radiotherapy is the most useful mode of palliative treatment for all forms of Kaposi's sarcoma in southern African patients.

Modification of a Superficial X-Ray Therapy Machine for Rectal Contact Therapy: Preliminary results

X-ray therapy of superficial rectal cancers using a hand-held 50kV contact unit (Philips RT-50) in a technique first described by Papillon had reached a point of widening clinical acceptability when the manufacturer of this equipment discontinued its production. To pursue this endocavitary approach to rectal therapy, technical modifications have to be made to conventional superficial x-ray therapy machines. Advantages over the original Papillon method include remote viewing of the lesion through the proctoscopic cone and a lower radiation exposure for the operator. We have evaluated a Bucky Combination Therapy Unit under conditions in which the operating voltage (65kV), target skin distance (23.6cm), and added filtration (0.39mm Al) were selected in order to match as closely as possible the beam penetration characteristics of the “standard” (Papillon) technique. With this equipment, the thermal characteristics of the tube anode and housing limit the amount of radiation that can be delivered before a “rest period” for the machine is needed. In practice, 3 minutes of irradiation at an exposure rate of 500R/min can be performed followed by an interval of 3 minutes before irradiation can be resumed.

Postoperative irradiation of keloids: Analysis of 125 patients

Between October 1985 and June 1992 Postoperative keloids of 125 Patients were treated with superficial X-ray (100–140 Kv) and electron beam (6 and 9 MeV ), in an attempt to prevent their recurrence, 100 patients with 129 sites received a dose of 1200 – 4000 cGy at 200 – 300 cGy per fraction within one to four weeks and at intervals of one to three weeks between excision and irradiation. Rate of success in the prevention of keloid was only 28. 6% (37/129). However, 25 patients with 25 sites received a total dose of 1500 cGy at 500 cGy per fraction starting within one week after excision and at intervals of 96 hours. The success rate was 84% (21/25).

Cartilage: The ‘F’-factor fallacy

It remains common practice to treat skin lesions overlying cartilage with electrons, apparently because of an assumption that radiation absorption qualities of non-calcified cartilage are similar to those of bone. We present data based on tissue composition and calculated mass absorption coefficients, supporting the view that such lesions may safely be treated with superficial X-rays.

Merkel cell (trabecular) carcinoma of skin treated by radiotherapy

Merkel cell tumour is a recently described aggressive primary neoplasm of the skin. It is commonly seen in the elderly, on the head and neck or extremities. Surgical excision is the recommended treatment, but local recurrence or dissemination is not an uncommon consequence of this form of therapy. Radiotherapy is usually used as a palliative treatment for metastatic disease. We present two patients, in one an extensive primary was controlled by superficial X-ray, in the other, lymph node metastases were controlled with radiotherapy after excision of the primary.

Dermatologic Radiation and Cancer

To the Editor.— The editorial in the July 1989 issue of theArchivesrequires a response. Burns 1 confuses grenz ray therapy with superficial radiation, overestimates the cancer risk following grenz ray therapy, and thereby invites confusion. A common mistake made by Burns in this editorial is grouping grenz ray with other x-ray modalities, and it is the purpose of this letter to report the existing risk estimates and to clarify the confusion between grenz rays and superficial x-rays. Grenz ray is defined as that x-ray having a half-value layer between 0.016 and 0.035 mm of aluminum, or a tube voltage of from 10 to 15 kV (50% of grenz rays are absorbed by 0.5 mm of skin). 2 Burns 1 states, Nevertheless, several studies have established the carcinogenicity of skin radiation therapies by conducting long-term follow-up of patients exposed to ionizing radiation in the form of low-voltage x-rays or

Malignant Melanoma at Sites of Therapeutic X-Irradiation

Two patients are reported in whom malignant melanoma developed at sites of low-dose superficial X-ray therapy given for treatment of benign dermatoses. No causal link has been established between melanoma and X-irradiation, but previous reports of a possible association are reviewed. The probably importance of ultraviolet exposure after X-irradiation in such patients is emphasised.

Dosimetric evaluation of a variable energy superficial x-ray machine with applications for endocavitary radiotherapy techniques

This investigation presents the beam characteristics of a newly-marketed variable energy superficial X ray machine for radiotherapy. The X ray system hardware, including a high voltage generator, and console software allow for nine independent operator-selected X ray beams from 10–150 kVp. Filament current values are also independently variable; 1.0–13.0 mA for 90–150 kVp, and 1.0–30.0 mA for 10–90 kVp. The HVL's, effective energies, and radiation outputs for the nine combinations of kVp and mA are presented. In addition, percentage depth dose and beam uniformity results are presented as a function of cone size. Radiation output stability and reproducibility results are included. Discussion of adaption of this X ray system to the Papillon technique for the treatment of rectal cancers is presented.

Measurement of residual stresses by X-ray diffraction in a [formula omitted] system obtained by high temperature oxidation

The resistance of metallic materials to high temperature oxidation is strongly linked with the adherence of the oxide layers developed on its surface and thus with the internal stresses of the metal-oxide system. The study of these stresses is delicate and the measurements are, more often than not, indirect. By using the non-destructive and superficial X-ray diffraction measurement, we have analysed the evolution of residual stresses (after returning to ambient temperature) in the Ni NiO system. The oxidation has been performed in air, at 900°C. After perfecting the experimental conditions of the analysis, we have calculated and measured the Radiocrystallographic Elastic Constants required for stress calculation. In NiO, the stresses are compressive. They may reach −600 MPa. This value increases at first and then diminishes when the thickness of the oxide layer increases. The maximum position depends on the Ni substrate thickness. The weaker the initial substrate roughness, the higher the stresses in the oxide (−400 to −600 MPa for polished samples, −100 to −300 MPa for shot-peened samples). The width of the diffraction peaks, index of the quantity of defects in NiO, is small. It diminishes when NiO thickness increases. This may be explained by the gradient of ponctuai defects and dislocations in NiO. Residual stresses in Ni-substrate, in the layers near the interface, are almost zero.

Rectal carcinoma: treatment with Papillon technique and fiberoptic-guided methods.

An adaptation of the Papillon technique was developed in which a superficial x-ray machine was used for treatment of small superficially invasive rectal carcinomas. Modification of the proctoscope-treatment cone apparatus, including addition of a fiberoptic scope, allows confirmation of accurate cone placement throughout the entire treatment. There is no personnel exposure to radiation. Measured physics beam characteristics are clinically comparable to those reported for the Papillon treatment beam.